40 CFR 264.1061 - Alternative standards for valves in gas/vapor service or in light liquid service: percentage of...

Code of Federal Regulations, 2013 CFR

2013-07-01

... gas/vapor service or in light liquid service: percentage of valves allowed to leak. 264.1061 Section... Emission Standards for Equipment Leaks § 264.1061 Alternative standards for valves in gas/vapor service or in light liquid service: percentage of valves allowed to leak. (a) An owner or operator subject to...

40 CFR 264.1061 - Alternative standards for valves in gas/vapor service or in light liquid service: percentage of...

Code of Federal Regulations, 2011 CFR

2011-07-01

... gas/vapor service or in light liquid service: percentage of valves allowed to leak. 264.1061 Section... Emission Standards for Equipment Leaks § 264.1061 Alternative standards for valves in gas/vapor service or in light liquid service: percentage of valves allowed to leak. (a) An owner or operator subject to...

40 CFR 264.1061 - Alternative standards for valves in gas/vapor service or in light liquid service: percentage of...

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas/vapor service or in light liquid service: percentage of valves allowed to leak. 264.1061 Section... Emission Standards for Equipment Leaks § 264.1061 Alternative standards for valves in gas/vapor service or in light liquid service: percentage of valves allowed to leak. (a) An owner or operator subject to...

40 CFR 264.1061 - Alternative standards for valves in gas/vapor service or in light liquid service: percentage of...

Code of Federal Regulations, 2012 CFR

2012-07-01

... gas/vapor service or in light liquid service: percentage of valves allowed to leak. 264.1061 Section... Emission Standards for Equipment Leaks § 264.1061 Alternative standards for valves in gas/vapor service or in light liquid service: percentage of valves allowed to leak. (a) An owner or operator subject to...

40 CFR 264.1061 - Alternative standards for valves in gas/vapor service or in light liquid service: percentage of...

Code of Federal Regulations, 2010 CFR

2010-07-01

... gas/vapor service or in light liquid service: percentage of valves allowed to leak. 264.1061 Section... Emission Standards for Equipment Leaks § 264.1061 Alternative standards for valves in gas/vapor service or in light liquid service: percentage of valves allowed to leak. (a) An owner or operator subject to...

40 CFR 265.1061 - Alternative standards for valves in gas/vapor service or in light liquid service: percentage of...

Code of Federal Regulations, 2013 CFR

2013-07-01

... gas/vapor service or in light liquid service: percentage of valves allowed to leak. 265.1061 Section... FACILITIES Air Emission Standards for Equipment Leaks § 265.1061 Alternative standards for valves in gas/vapor service or in light liquid service: percentage of valves allowed to leak. (a) An owner or operator...

40 CFR 265.1061 - Alternative standards for valves in gas/vapor service or in light liquid service: percentage of...

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas/vapor service or in light liquid service: percentage of valves allowed to leak. 265.1061 Section... FACILITIES Air Emission Standards for Equipment Leaks § 265.1061 Alternative standards for valves in gas/vapor service or in light liquid service: percentage of valves allowed to leak. (a) An owner or operator...

The Shuttle Orbital Maneuvering System P-V-T Propellant Quantity Gaging Accuracy and Leak Detection Allowance for Four Instrumentation Conditions

NASA Technical Reports Server (NTRS)

Duhon, D. D.

1975-01-01

The shuttle orbital maneuvering system (OMS) pressure-volume-temperature (P-V-T) propellant gaging module computes the quantity of usable OMS propellant remaining based on the real gas P-V-T relationship for the propellant tank pressurant, helium. The OMS P-V-T propellant quantity gaging error was determined for four sets of instrumentation configurations and accuracies with the propellant tank operating in the normal constant pressure mode and in the blowdown mode. The instrumentation inaccuracy allowance for propellant leak detection was also computed for these same four sets of instrumentation. These gaging errors and leak detection allowances are presented in tables designed to permit a direct comparison of the effectiveness of the four instrumentation sets. The results show the magnitudes of the improvements in propellant quantity gaging accuracies and propellant leak detection allowances which can be achieved by employing more accurate pressure and temperature instrumentation.

Mapping urban pipeline leaks: methane leaks across Boston.

PubMed

Phillips, Nathan G; Ackley, Robert; Crosson, Eric R; Down, Adrian; Hutyra, Lucy R; Brondfield, Max; Karr, Jonathan D; Zhao, Kaiguang; Jackson, Robert B

2013-02-01

Natural gas is the largest source of anthropogenic emissions of methane (CH(4)) in the United States. To assess pipeline emissions across a major city, we mapped CH(4) leaks across all 785 road miles in the city of Boston using a cavity-ring-down mobile CH(4) analyzer. We identified 3356 CH(4) leaks with concentrations exceeding up to 15 times the global background level. Separately, we measured δ(13)CH(4) isotopic signatures from a subset of these leaks. The δ(13)CH(4) signatures (mean = -42.8‰ ± 1.3‰ s.e.; n = 32) strongly indicate a fossil fuel source rather than a biogenic source for most of the leaks; natural gas sampled across the city had average δ(13)CH(4) values of -36.8‰ (± 0.7‰ s.e., n = 10), whereas CH(4) collected from landfill sites, wetlands, and sewer systems had δ(13)CH(4) signatures ~20‰ lighter (μ = -57.8‰, ± 1.6‰ s.e., n = 8). Repairing leaky natural gas distribution systems will reduce greenhouse gas emissions, increase consumer health and safety, and save money. Copyright © 2012 Elsevier Ltd. All rights reserved.

Neonatal hygroscopic condenser humidifier.

PubMed

Gedeon, A; Mebius, C; Palmer, K

1987-01-01

A hygroscopic condenser humidifier was developed for neonates on mechanical ventilation and was evaluated by laboratory tests and clinically. Humidification provided by the unit was measured in the 10- to 50-ml tidal-volume range at ambient temperatures of 24 degrees C and 38 degrees C. The effect of a leaking patient connection on device performance was investigated. Leakage rates were measured routinely in a neonatal ICU and surgery to determine the clinical significance. In the entire tidal volume and temperature range, the unit provided an inspiratory water content in excess of 30 g/m3 when the leak fraction (volume leaked/volume delivered at Y-piece) was less than 15%. This was found in three out of four cases. In about one out of ten cases, the leak exceeded 30%, which invariably led to corrective action, such as repositioning or changing the endotracheal tube. However, even at a 30% leak, a water content of about 26 g/m3 was still available for humidifying the inspired gas, which corresponds to normal physiologic conditions found in the trachea for nasal breathing of room air.

Assessment of volume and leak measurements during CPAP using a neonatal lung model.

PubMed

Fischer, H S; Roehr, C C; Proquitté, H; Wauer, R R; Schmalisch, G

2008-01-01

Although several commercial devices are available which allow tidal volume and air leak monitoring during continuous positive airway pressure (CPAP) in neonates, little is known about their measurement accuracy and about the influence of air leaks on volume measurement. The aim of this in vitro study was the validation of volume and leak measurement under CPAP using a commercial ventilatory device, taking into consideration the clinical conditions in neonatology. The measurement accuracy of the Leoni ventilator (Heinen & Löwenstein, Germany) was investigated both in a leak-free system and with leaks simulated using calibration syringes (2-10 ml, 20-100 ml) and a mechanical lung model. Open tubes of variable lengths were connected for leak simulation. Leak flow was measured with the flow-through technique. In a leak-free system the mean relative volume error +/-SD was 3.5 +/- 2.6% (2-10 ml) and 5.9 +/- 0.7% (20-60 ml), respectively. The influence of CPAP level, driving flow, respiratory rate and humidification of the breathing gas on the volume error was negligible. However, an increasing F(i)O(2) caused the measured tidal volume to increase by up to 25% (F(i)O(2) = 1.0). The relative error +/- SD of the leak measurements was -0.2 +/- 11.9%. For leaks > 19%, measured tidal volume was underestimated by more than 10%. In conclusion, the present in vitro study showed that the Leoni allowed accurate volume monitoring under CPAP conditions similar to neonates. Air leaks of up to 90% of patient flow were reliably detected. For an F(i)O(2) > 0.4 and for leaks > 19%, a numerical correction of the displayed volume should be performed.

Cost Analysis of Cerebrospinal Fluid Leaks and Cerebrospinal Fluid Leak Prevention in Patients Undergoing Cerebellopontine Angle Surgery.

PubMed

Chern, Alexander; Hunter, Jacob B; Bennett, Marc L

2017-01-01

To determine if cranioplasty techniques following translabyrinthine approaches to the cerebellopontine angle are cost-effective. Retrospective case series. One hundred eighty patients with available financial data who underwent translabyrinthine approaches at a single academic referral center between 2005 and 2015. Cranioplasty with a dural substitute, layered fat graft, and a resorbable mesh plate secured with screws Main Outcome Measures: billing data was obtained for each patient's hospital course for translabyrinthine approaches and postoperative cerebrospinal fluid (CSF) leaks. One hundred nineteen patients underwent translabyrinthine approaches with an abdominal fat graft closure, with a median cost of $25759.89 (range, $15885.65-$136433.07). Sixty-one patients underwent translabyrinthine approaches with a dural substitute, abdominal fat graft, and a resorbable mesh for closure, with a median cost of $29314.97 (range, $17674.28-$111404.55). The median cost of a CSF leak was $50401.25 (range, $0-$384761.71). The additional cost of a CSF leak when shared by all patients who underwent translabyrinthine approaches is $6048.15. The addition of a dural substitute and a resorbable mesh plate after translabyrinthine approaches reduced the CSF leak from 12 to 1.9%, an 84.2% reduction, and a median savings per patient of $2932.23. Applying our cohort's billing data to previously published cranioplasty techniques, costs, and leak rate improvements after translabyrinthine approaches, all techniques were found to be cost-effective. Resorbable mesh cranioplasty is cost-effective at reducing CSF leaks after translabyrinthine approaches. Per our billing data and achieving the same CSF leak rate, cranioplasty costs exceeding $5090.53 are not cost-effective.

40 CFR Table 2 to Subpart Mmm of... - Standards for New and Existing PAI Sources

Code of Federal Regulations, 2012 CFR

2012-07-01

... a HAP Particulate matter concentration not to exceed 0.01 gr/dscf. Heat exchange systems Each heat exchange system used to cool process equipment in PAI manufacturing operations Monitoring and leak repair...

40 CFR Table 2 to Subpart Mmm of... - Standards for New and Existing PAI Sources

Code of Federal Regulations, 2011 CFR

2011-07-01

... a HAP Particulate matter concentration not to exceed 0.01 gr/dscf. Heat exchange systems Each heat exchange system used to cool process equipment in PAI manufacturing operations Monitoring and leak repair...

78 FR 37133 - National Emission Standards for Hazardous Air Pollutants From Petroleum Refineries

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-20

... systems that would allow owners and operators at existing sources to monitor quarterly using a leak action... option, which requires monitoring monthly at a leak action level defined as a total strippable... monitoring alternative and the modeling indicates that quarterly monitoring at the lower leak action level...

49 CFR 173.475 - Quality control requirements prior to each shipment of Class 7 (radioactive) materials.

Code of Federal Regulations, 2010 CFR

2010-10-01

... A2 quantity and intended for air shipment has been tested to show that it will not leak under an... exceed the design pressure during transportation; and (i) External radiation and contamination levels are...

49 CFR 190.341 - Special permits.

Code of Federal Regulations, 2013 CFR

2013-10-01

... information including operating pressure, leak history, and most recent testing or assessment results; (3) A... equipment, insufficient manpower); (3) A statement indicating how operating the pipeline pursuant to an... damages a pipeline facility resulting in death, serious bodily harm, or property damage exceeding $50,000...

Monitoring of noninvasive ventilation by built-in software of home bilevel ventilators: a bench study.

PubMed

Contal, Olivier; Vignaux, Laurence; Combescure, Christophe; Pepin, Jean-Louis; Jolliet, Philippe; Janssens, Jean-Paul

2012-02-01

Current bilevel positive-pressure ventilators for home noninvasive ventilation (NIV) provide physicians with software that records items important for patient monitoring, such as compliance, tidal volume (Vt), and leaks. However, to our knowledge, the validity of this information has not yet been independently assessed. Testing was done for seven home ventilators on a bench model adapted to simulate NIV and generate unintentional leaks (ie, other than of the mask exhalation valve). Five levels of leaks were simulated using a computer-driven solenoid valve (0-60 L/min) at different levels of inspiratory pressure (15 and 25 cm H(2)O) and at a fixed expiratory pressure (5 cm H(2)O), for a total of 10 conditions. Bench data were compared with results retrieved from ventilator software for leaks and Vt. For assessing leaks, three of the devices tested were highly reliable, with a small bias (0.3-0.9 L/min), narrow limits of agreement (LA), and high correlations (R(2), 0.993-0.997) when comparing ventilator software and bench results; conversely, for four ventilators, bias ranged from -6.0 L/min to -25.9 L/min, exceeding -10 L/min for two devices, with wide LA and lower correlations (R(2), 0.70-0.98). Bias for leaks increased markedly with the importance of leaks in three devices. Vt was underestimated by all devices, and bias (range, 66-236 mL) increased with higher insufflation pressures. Only two devices had a bias < 100 mL, with all testing conditions considered. Physicians monitoring patients who use home ventilation must be aware of differences in the estimation of leaks and Vt by ventilator software. Also, leaks are reported in different ways according to the device used.

A Hydrogen Leak Detection System for Aerospace and Commercial Applications

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Makel, D. B.; Jansa, E. D.; Patterson, G.; Cova, P. J.; Liu, C. C.; Wu, Q. H.; Powers, W. T.

1995-01-01

Leaks on the space shuttle while on the launch pad have generated interest in hydrogen leak monitoring technology. Microfabricated hydrogen sensors are being fabricated at Case Western Reserve University (CWRU) and tested at NASA Lewis Research Center (LeRC). These sensors have been integrated into hardware and software designed by Aerojet. This complete system allows for multipoint leak monitoring designed to provide leak source and magnitude information in real time. The monitoring system processes data from the hydrogen sensors and presents the operator with a visual indication of the leak location and magnitude. Although the leak monitoring system was designed for hydrogen propulsion systems, the possible applications of this monitoring system are wide ranged. This system is in operation in an automotive application which requires high sensitivity to hydrogen.

A risk-based approach to flammable gas detector spacing.

PubMed

Defriend, Stephen; Dejmek, Mark; Porter, Leisa; Deshotels, Bob; Natvig, Bernt

2008-11-15

Flammable gas detectors allow an operating company to address leaks before they become serious, by automatically alarming and by initiating isolation and safe venting. Without effective gas detection, there is very limited defense against a flammable gas leak developing into a fire or explosion that could cause loss of life or escalate to cascading failures of nearby vessels, piping, and equipment. While it is commonly recognized that some gas detectors are needed in a process plant containing flammable gas or volatile liquids, there is usually a question of how many are needed. The areas that need protection can be determined by dispersion modeling from potential leak sites. Within the areas that must be protected, the spacing of detectors (or alternatively, number of detectors) should be based on risk. Detector design can be characterized by spacing criteria, which is convenient for design - or alternatively by number of detectors, which is convenient for cost reporting. The factors that influence the risk are site-specific, including process conditions, chemical composition, number of potential leak sites, piping design standards, arrangement of plant equipment and structures, design of isolation and depressurization systems, and frequency of detector testing. Site-specific factors such as those just mentioned affect the size of flammable gas cloud that must be detected (within a specified probability) by the gas detection system. A probability of detection must be specified that gives a design with a tolerable risk of fires and explosions. To determine the optimum spacing of detectors, it is important to consider the probability that a detector will fail at some time and be inoperative until replaced or repaired. A cost-effective approach is based on the combined risk from a representative selection of leakage scenarios, rather than a worst-case evaluation. This means that probability and severity of leak consequences must be evaluated together. In marine and offshore facilities, it is conventional to use computational fluid dynamics (CFD) modeling to determine the size of a flammable cloud that would result from a specific leak scenario. Simpler modeling methods can be used, but the results are not very accurate in the region near the release, especially where flow obstructions are present. The results from CFD analyses on several leak scenarios can be plotted to determine the size of a flammable cloud that could result in an explosion that would generate overpressure exceeding the strength of the mechanical design of the plant. A cloud of this size has the potential to produce a blast pressure or flying debris capable of causing a fatality or subsequent damage to vessels or piping containing hazardous material. In cases where the leak results in a fire, rather than explosion, CFD or other modeling methods can estimate the size of a leak that would cause a fire resulting in subsequent damage to the facility, or would prevent the safe escape of personnel. The gas detector system must be capable of detecting a gas release or vapor cloud, and initiating action to prevent the leak from reaching a size that could cause injury or severe damage upon ignition.

Evaluating All-Metal Valves for Use in a Tritium Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Houk, L.; Payton, A.

In the tritium gas processing system, it is desired to minimize polymer components due to their degradation from tritium exposure (beta decay). One source of polymers in the tritium process is valve components. A vendor has been identified that manufactures a valve that is marketed as being made from all-metal construction. This manufacturer, Ham-Let Group, manufactures a diaphragm valve (3LE series) that claims to be made entirely of metal. SRNL procured twelve (12) Ham-Let diaphragm valves for characterization and evaluation. The characterization tests include identification of the maximum pressure of these valves by performing pressure and burst tests. Leak testsmore » were performed to ensure the valves do not exceed the acceptable leak rate for tritium service. These valves were then cycled in a nitrogen gas and/or vacuum environment to ensure they would be durable in a process environment. They were subsequently leak tested per ASTM protocol to ensure that the valves maintained their leak tight integrity. A detailed material analysis was also conducted to determine hydrogen and tritium compatibility.« less

Development of a leak location system for use on underground electric power transmission cable

NASA Astrophysics Data System (ADS)

Williams, J. A.

1982-10-01

This report describes a study to evaluate methods for locating leaks of dielectric fluid from buried high voltage cable systems. Two primary types of leak location systems were investigated: (1) systems that will rapidly isolate the leak within a manhole section, typically 1000 m long on a feeder that might be 30 km long; and (2) systems that will then pinpoint the location of the leak. Rapid leak isolation was accomplished by developing an enhanced conductivity oil probe which allows the injection of a small quantity of conductive oil and which indicates the path of the oil as it drifts downstream in the direction of the leak. Two methods for pinpointing the leak were proven. The more successful method was the use of trained leak location dogs which were found to have far better sensitivity than instruments and which could detect cable oil alone without the need for additives. A tracer gas injection and detection scheme was developed for use in areas where the dogs may be unsuitable.

Fuel containment, lightning protection and damage tolerance in large composite primary aircraft structures

NASA Technical Reports Server (NTRS)

Griffin, Charles F.; James, Arthur M.

1985-01-01

The damage-tolerance characteristics of high strain-to-failure graphite fibers and toughened resins were evaluated. Test results show that conventional fuel tank sealing techniques are applicable to composite structures. Techniques were developed to prevent fuel leaks due to low-energy impact damage. For wing panels subjected to swept stroke lightning strikes, a surface protection of graphite/aluminum wire fabric and a fastener treatment proved effective in eliminating internal sparking and reducing structural damage. The technology features developed were incorporated and demonstrated in a test panel designed to meet the strength, stiffness, and damage tolerance requirements of a large commercial transport aircraft. The panel test results exceeded design requirements for all test conditions. Wing surfaces constructed with composites offer large weight savings if design allowable strains for compression can be increased from current levels.

Scanning, standoff TDLAS leak imaging and quantification

NASA Astrophysics Data System (ADS)

Wainner, Richard T.; Aubut, Nicholas F.; Laderer, Matthew C.; Frish, Michael B.

2017-05-01

This paper reports a novel quantitative gas plume imaging tool, based on active near-infrared Backscatter Tunable Diode Laser Absorption Spectroscopy (b-TDLAS) technology, designed for upstream natural gas leak applications. The new tool integrates low-cost laser sensors with video cameras to create a highly sensitive gas plume imager that also quantifies emission rate, all in a lightweight handheld ergonomic package. It is intended to serve as a lower-cost, higherperformance, enhanced functionality replacement for traditional passive non-quantitative mid-infrared Optical Gas Imagers (OGI) which are utilized by industry to comply with natural gas infrastructure Leak Detection and Repair (LDAR) requirements. It addresses the need for reliable, robust, low-cost sensors to detect and image methane leaks, and to quantify leak emission rates, focusing on inspections of upstream oil and gas operations, such as well pads, compressors, and gas plants. It provides: 1) Colorized quantified images of path-integrated methane concentration. The images depict methane plumes (otherwise invisible to the eye) actively interrogated by the laser beam overlaid on a visible camera image of the background. The detection sensitivity exceeds passive OGI, thus simplifying the manual task of leak detection and location; and 2) Data and algorithms for using the quantitative information gathered by the active detection technique to deduce plume flux (i.e. methane emission rate). This key capability will enable operators to prioritize leak repairs and thereby minimize the value of lost product, as well as to quantify and minimize greenhouse gas emissions, using a tool that meets EPA LDAR imaging equipment requirements.

Fibrin glue as agent for sealing corneal and conjunctival wound leaks.

PubMed

Scalcione, C; Ortiz-Vaquerizas, D; Said, D G; Dua, H S

2018-02-01

PurposeTo describe a novel use of fibrin glue in managing leaking blebs and leaking wounds following trauma or surgery.MethodsInterventional case series.ResultsWe report eight patients, including three where intra-operative or immediate post-penetrating keratoplasty recalcitrant leaks from the graft-host junction and/or openings created by the needle pass, were noted. All three had thin recipient beds in the sector of leak. This was managed by intra-cameral injection of fibrin glue in the affected quadrant. This stopped the leak and allowed the defect to heal. One patient of Descemets-stripping-endothelial-keratoplasty had leak from the surgical wound, which was also sealed with fibrin glue. Two patients with leaking glaucoma-surgery-related blebs were treated with intra-bleb injection of fibrin glue to stop the leak. One patient with a penetrating corneal injury with a metal wire had a brisk leak upon removal of the wire. This was sealed with fibrin glue. Another patient of chemical burn with spontaneous leaks was managed by glue injection in the perforations. Transient rise of intraocular pressure in one patient with a leaking bleb was the only adverse event recorded.ConclusionThis novel adaptation of the application of fibrin glue can help to deal with persistent intra-operative, post-operative and traumatic aqueous and air leaks.

Air-Leak Effects on Ear-Canal Acoustic Absorbance

PubMed Central

Rasetshwane, Daniel M.; Kopun, Judy G.; Gorga, Michael P.; Neely, Stephen T.

2015-01-01

Objective: Accurate ear-canal acoustic measurements, such as wideband acoustic admittance, absorbance, and otoacoustic emissions, require that the measurement probe be tightly sealed in the ear canal. Air leaks can compromise the validity of the measurements, interfere with calibrations, and increase variability. There are no established procedures for determining the presence of air leaks or criteria for what size leak would affect the accuracy of ear-canal acoustic measurements. The purpose of this study was to determine ways to quantify the effects of air leaks and to develop objective criteria to detect their presence. Design: Air leaks were simulated by modifying the foam tips that are used with the measurement probe through insertion of thin plastic tubing. To analyze the effect of air leaks, acoustic measurements were taken with both modified and unmodified foam tips in brass-tube cavities and human ear canals. Measurements were initially made in cavities to determine the range of critical leaks. Subsequently, data were collected in ears of 21 adults with normal hearing and normal middle-ear function. Four acoustic metrics were used for predicting the presence of air leaks and for quantifying these leaks: (1) low-frequency admittance phase (averaged over 0.1–0.2 kHz), (2) low-frequency absorbance, (3) the ratio of compliance volume to physical volume (CV/PV), and (4) the air-leak resonance frequency. The outcome variable in this analysis was the absorbance change (Δabsorbance), which was calculated in eight frequency bands. Results: The trends were similar for both the brass cavities and the ear canals. ΔAbsorbance generally increased with air-leak size and was largest for the lower frequency bands (0.1–0.2 and 0.2–0.5 kHz). Air-leak effects were observed in frequencies up to 10 kHz, but their effects above 1 kHz were unpredictable. These high-frequency air leaks were larger in brass cavities than in ear canals. Each of the four predictor variables exhibited consistent dependence on air-leak size. Low-frequency admittance phase and CV/PV decreased, while low-frequency absorbance and the air-leak resonance frequency increased. Conclusion: The effect of air leaks can be significant when their equivalent diameter exceeds 0.01 in. The observed effects were greatest at low frequencies where air leaks caused absorbance to increase. Recommended criteria for detecting air leaks include the following: when the frequency range of interest extends as low as 0.1 kHz, low-frequency absorbance should be ≤0.20 and low-frequency admittance phase ≥61 degrees. For frequency ranges as low as 0.2 kHz, low-frequency absorbance should be ≤0.29 and low-frequency admittance phase ≥44 degrees. PMID:25170779

Air-leak effects on ear-canal acoustic absorbance.

PubMed

Groon, Katherine A; Rasetshwane, Daniel M; Kopun, Judy G; Gorga, Michael P; Neely, Stephen T

2015-01-01

Accurate ear-canal acoustic measurements, such as wideband acoustic admittance, absorbance, and otoacoustic emissions, require that the measurement probe be tightly sealed in the ear canal. Air leaks can compromise the validity of the measurements, interfere with calibrations, and increase variability. There are no established procedures for determining the presence of air leaks or criteria for what size leak would affect the accuracy of ear-canal acoustic measurements. The purpose of this study was to determine ways to quantify the effects of air leaks and to develop objective criteria to detect their presence. Air leaks were simulated by modifying the foam tips that are used with the measurement probe through insertion of thin plastic tubing. To analyze the effect of air leaks, acoustic measurements were taken with both modified and unmodified foam tips in brass-tube cavities and human ear canals. Measurements were initially made in cavities to determine the range of critical leaks. Subsequently, data were collected in ears of 21 adults with normal hearing and normal middle-ear function. Four acoustic metrics were used for predicting the presence of air leaks and for quantifying these leaks: (1) low-frequency admittance phase (averaged over 0.1-0.2 kHz), (2) low-frequency absorbance, (3) the ratio of compliance volume to physical volume (CV/PV), and (4) the air-leak resonance frequency. The outcome variable in this analysis was the absorbance change (Δabsorbance), which was calculated in eight frequency bands. The trends were similar for both the brass cavities and the ear canals. ΔAbsorbance generally increased with air-leak size and was largest for the lower frequency bands (0.1-0.2 and 0.2-0.5 kHz). Air-leak effects were observed in frequencies up to 10 kHz, but their effects above 1 kHz were unpredictable. These high-frequency air leaks were larger in brass cavities than in ear canals. Each of the four predictor variables exhibited consistent dependence on air-leak size. Low-frequency admittance phase and CV/PV decreased, while low-frequency absorbance and the air-leak resonance frequency increased. The effect of air leaks can be significant when their equivalent diameter exceeds 0.01 in. The observed effects were greatest at low frequencies where air leaks caused absorbance to increase. Recommended criteria for detecting air leaks include the following: when the frequency range of interest extends as low as 0.1 kHz, low-frequency absorbance should be ≤0.20 and low-frequency admittance phase ≥61 degrees. For frequency ranges as low as 0.2 kHz, low-frequency absorbance should be ≤0.29 and low-frequency admittance phase ≥44 degrees.

Identification of sewage leaks by active remote-sensing methods

NASA Astrophysics Data System (ADS)

Goldshleger, Naftaly; Basson, Uri

2016-04-01

The increasing length of sewage pipelines, and concomitant risk of leaks due to urban and industrial growth and development is exposing the surrounding land to contamination risk and environmental harm. It is therefore important to locate such leaks in a timely manner, to minimize the damage. Advances in active remote sensing Ground Penetrating Radar (GPR) and Frequency Domain Electromagnetic (FDEM) technologies was used to identify leaking potentially responsible for pollution and to identify minor spills before they cause widespread damage. This study focused on the development of these electromagnetic methods to replace conventional acoustic methods for the identification of leaks along sewage pipes. Electromagnetic methods provide an additional advantage in that they allow mapping of the fluid-transport system in the subsurface. Leak-detection systems using GPR and FDEM are not limited to large amounts of water, but enable detecting leaks of tens of liters per hour, because they can locate increases in environmental moisture content of only a few percentage along the pipes. The importance and uniqueness of this research lies in the development of practical tools to provide a snapshot and monitoring of the spatial changes in soil moisture content up to depths of about 3-4 m, in open and paved areas, at relatively low cost, in real time or close to real time. Spatial measurements performed using GPR and FDEM systems allow monitoring many tens of thousands of measurement points per hectare, thus providing a picture of the spatial situation along pipelines and the surrounding. The main purpose of this study was to develop a method for detecting sewage leaks using the above-proposed geophysical methods, since their contaminants can severely affect public health. We focused on identifying, locating and characterizing such leaks in sewage pipes in residential and industrial areas.

Optimal sensor placement for leak location in water distribution networks using genetic algorithms.

PubMed

Casillas, Myrna V; Puig, Vicenç; Garza-Castañón, Luis E; Rosich, Albert

2013-11-04

This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach.

Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms

PubMed Central

Casillas, Myrna V.; Puig, Vicenç; Garza-Castañón, Luis E.; Rosich, Albert

2013-01-01

This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach. PMID:24193099

Probabilistic pipe fracture evaluations for leak-rate-detection applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, S.; Ghadiali, N.; Paul, D.

1995-04-01

Regulatory Guide 1.45, {open_quotes}Reactor Coolant Pressure Boundary Leakage Detection Systems,{close_quotes} was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, {open_quotes}Leak Before Break Evaluation Procedures{close_quotes} where a margin of 10 on the leak detection limit is used in determining the crackmore » size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break.« less

Leak test adapter for containers

DOEpatents

Hallett, Brian H.; Hartley, Michael S.

1996-01-01

An adapter is provided for facilitating the charging of containers and leak testing penetration areas. The adapter comprises an adapter body and stem which are secured to the container's penetration areas. The container is then pressurized with a tracer gas. Manipulating the adapter stem installs a penetration plug allowing the adapter to be removed and the penetration to be leak tested with a mass spectrometer. Additionally, a method is provided for using the adapter.

Performance of the PneuX System: A Bench Study Comparison With 4 Other Endotracheal Tube Cuffs.

PubMed

Chenelle, Christopher T; Itagaki, Taiga; Fisher, Daniel F; Berra, Lorenzo; Kacmarek, Robert M

2017-01-01

Cuff design affects microaspiration, a risk factor for pneumonia. We questioned whether the PneuX low-volume fold-free cuff design would prevent cuff leakage and maintain the same tracheal wall pressure as high-volume, low-pressure (HVLP) cuffs. We evaluated 4 HVLP-cuffed endotracheal tubes (ETTs), Hi-Lo (polyvinyl chloride [PVC]), Microcuff (polyurethane [PU]), SealGuard (PU + tapered), and TaperGuard (PVC + tapered), and the PneuX with its dedicated tracheal seal monitor. In Part 1, we determined tracheal wall pressure using each cuff's capacity to support water columns across recommended intracuff pressures. In Part 2, we evaluated the tracheal seal monitor function at recommended settings. In Part 3, we compared leakage volumes of all ETTs during 30 min of simulated mechanical ventilation or during 8 h if no leak occurred. Parts 1 and 3 were performed with/without lubrication and PEEP. In Part 1, PneuX cuffs exerted an average tracheal wall pressure of 27.4 ± 2.4 cm H 2 O at the recommended intracuff pressure of approximately 80 cm H 2 O. Tracheal wall pressure did not differ among HVLP cuffs (19.6 ± 1.4 to 29.5 ± 1.4 cm H 2 O). In Part 2, preinflation intracuff pressure affected the time to obtain tracheal seal monitor pressure attainment (P < .01). The tracheal seal monitor generated average calculated tracheal wall pressure of 33.4 ± 1.2 cm H 2 O. In Part 3, PneuX ETT showed no leak across 8 h for all trials. Overall, leakage volume was lower with PU (P < .01) and PneuX (P < .01) than with PVC cuffs, regardless of shape, and lower with lubrication and/or PEEP (all P < .01). In each HVLP cuff, lubrication alone eliminated leak at an intracuff pressure of ≤30 cm H 2 O. The PneuX cuff generally exerted acceptable tracheal wall pressure, but the tracheal wall pressure monitor allowed pressures exceeding 30 cm H 2 O in some trials and was the only ETT to prevent leak in all tests. For HVLP cuffs, leak was reduced by PU and PEEP and eliminated by lubrication. Copyright © 2017 by Daedalus Enterprises.

Closure of ascites leaks with fibrin glue injection in patients with end-stage liver disease.

PubMed

Sadik, Karim W; Laibstain, Sarah; Northup, Patrick G; Kashmer, David; Schmitt, Timothy M; Bonatti, Hugo J R

2011-09-01

Ascites leaks (AL) in patients with end-stage liver disease (ESLD) are associated with significant morbidity and mortality regardless if they are medically or surgically managed. In a pilot study, 14 ESLD patients with AL underwent treatment with fibrin glue injection around the leak after failing conservative therapy. The end point of this study was the cessation of AL in the short term and the maintenance of a leak-free abdomen in the long term, allowing for medical optimization of the patients. Median age of the 10 men and 4 women was 50 (range 26-67) years. Underlying ESLDs were chronic hepatitis C (n=5), alcoholic LD (n=2), cryptogenic cirrhosis (n=2), and miscellaneous (n=5). There were six leaking incisions posthernia repair (three umbilical and three inguinal), two leaking/ruptured umbilical hernias, four leaking paracentesis sites, one leaking Jackson-Pratt (JP) drain canal, and one leaking laparoscopic trocar site. Average AL volume per day was 1000 (range 400-2000) mL. All leaks were immediately resolved with a 3-5 mL fibrin glue injection. Five recurred and required a second injection (four within 24 hours). Mental status improved in 7 patients (West Haven Criteria: grade II to I [n=6], grade III to I [n=1]). Median model of end-stage liver disease scores improved from 23 (range 8-33) to 20 (range 14-26). There were no infections, bleeds, or other injection-related complications. Average follow-up for these patients was 441.6 days (range 2-852). Five patients underwent liver transplant (LT) median 15 (range 4-270) days postinjection; 2 of them died. Another 3 patients died (2 from sepsis and 1 from metastatic cancer). Fibrin glue injection for the control of AL is a simple and safe bedside procedure that quickly controls AL, allowing for patient recovery in anticipation of further care.

40 CFR 265.224 - Response actions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... action plan. The response action plan must set forth the actions to be taken if the action leakage rate... paragraph (b) of this section. (b) If the flow rate into the leak detection system exceeds the action leakage rate for any sump, the owner or operator must: (1) Notify the Regional Administrator in writing of...

Microphone Detects Boiler-Tube Leaks

NASA Technical Reports Server (NTRS)

Parthasarathy, S. P.

1985-01-01

Unit simple, sensitive, rugged, and reliable. Diaphragmless microphone detects leaks from small boiler tubes. Porous plug retains carbon granules in tube while allowing pressure changes to penetrate to granules. Has greater life expectancy than previous controllers and used in variety of hot corrosive atmospheres.

Powder metallurgy processing of high strength turbine disk alloys

NASA Technical Reports Server (NTRS)

Evans, D. J.

1976-01-01

Using vacuum-atomized AF2-1DA and Mar-M432 powders, full-scale gas turbine engine disks were fabricated by hot isostatically pressing (HIP) billets which were then isothermally forged using the Pratt & Whitney Aircraft GATORIZING forging process. While a sound forging was produced in the AF2-1DA, a container leak had occurred in the Mar-M432 billet during HIP. This resulted in billet cracking during forging. In-process control procedures were developed to identify such leaks. The AF2-1DA forging was heat treated and metallographic and mechanical property evaluation was performed. Mechanical properties exceeded those of Astroloy, one of the highest temperature capability turbine disk alloys presently used.

Passive air cooling of liquid metal-cooled reactor with double vessel leak accommodation capability

DOEpatents

Hunsbedt, A.; Boardman, C.E.

1995-04-11

A passive and inherent shutdown heat removal method with a backup air flow path which allows decay heat removal following a postulated double vessel leak event in a liquid metal-cooled nuclear reactor is disclosed. The improved reactor design incorporates the following features: (1) isolation capability of the reactor cavity environment in the event that simultaneous leaks develop in both the reactor and containment vessels; (2) a reactor silo liner tank which insulates the concrete silo from the leaked sodium, thereby preserving the silo`s structural integrity; and (3) a second, independent air cooling flow path via tubes submerged in the leaked sodium which will maintain shutdown heat removal after the normal flow path has been isolated. 5 figures.

Passive air cooling of liquid metal-cooled reactor with double vessel leak accommodation capability

DOEpatents

Hunsbedt, Anstein; Boardman, Charles E.

1995-01-01

A passive and inherent shutdown heat removal method with a backup air flow path which allows decay heat removal following a postulated double vessel leak event in a liquid metal-cooled nuclear reactor. The improved reactor design incorporates the following features: (1) isolation capability of the reactor cavity environment in the event that simultaneous leaks develop in both the reactor and containment vessels; (2) a reactor silo liner tank which insulates the concrete silo from the leaked sodium, thereby preserving the silo's structural integrity; and (3) a second, independent air cooling flow path via tubes submerged in the leaked sodium which will maintain shutdown heat removal after the normal flow path has been isolated.

Focused terahertz waves generated by a phase velocity gradient in a parallel-plate waveguide.

PubMed

McKinney, Robert W; Monnai, Yasuaki; Mendis, Rajind; Mittleman, Daniel

2015-10-19

We demonstrate the focusing of a free-space THz beam emerging from a leaky parallel-plate waveguide (PPWG). Focusing is accomplished by grading the launch angle of the leaky wave using a PPWG with gradient plate separation. Inside the PPWG, the phase velocity of the guided TE1 mode exceeds the vacuum light speed, allowing the wave to leak into free space from a slit cut along the top plate. Since the leaky wave angle changes as the plate separation decreases, the beam divergence can be controlled by grading the plate separation along the propagation axis. We experimentally demonstrate focusing of the leaky wave at a selected location at frequencies of 100 GHz and 170 GHz, and compare our measurements with numerical simulations. The proposed concept can be valuable for implementing a flat and wide-aperture beam-former for THz communications systems.

Grain-scale supercharging and breakdown on airless regoliths

NASA Astrophysics Data System (ADS)

Zimmerman, M. I.; Farrell, W. M.; Hartzell, C. M.; Wang, X.; Horanyi, M.; Hurley, D. M.; Hibbitts, K.

2016-10-01

Interactions of the solar wind and emitted photoelectrons with airless bodies have been studied extensively. However, the details of how charged particles interact with the regolith at the scale of a single grain have remained largely uncharacterized. Recent efforts have focused upon determining total surface charge under photoemission and solar wind bombardment and the associated electric field and potential. In this work, theory and simulations are used to show that grain-grain charge differences can exceed classical sheath predictions by several orders of magnitude, sometimes reaching dielectric breakdown levels. Temperature-dependent electrical conductivity works against supercharging by allowing current to leak through individual grains; the balance between internal conduction and surface charging controls the maximum possible grain-to-grain electric field. Understanding the finer details of regolith grain charging, conductive equilibrium, and dielectric breakdown will improve future numerical studies of space weathering and dust levitation on airless bodies.

Grain-Scale Supercharging and Breakdown on Airless Regoliths

NASA Technical Reports Server (NTRS)

Zimmerman, M. I.; Farrell, W. M.; Hartzell, C.M.; Wang, X.; Horanyi, M.; Hurley, D. M.; Hibbitts, K.

2016-01-01

Interactions of the solar wind and emitted photoelectrons with airless bodies have been studied extensively. However, the details of how charged particles interact with the regolith at the scale of a single grain have remained largely uncharacterized. Recent efforts have focused upon determining total surface charge under photoemission and solar wind bombardment and the associated electric field and potential. In this work, theory and simulations are used to show that grain-grain charge differences can exceed classical sheath predictions by several orders of magnitude, sometimes reaching dielectric breakdown levels. Temperature-dependent electrical conductivity works against supercharging by allowing current to leak through individual grains; the balance between internal conduction and surface charging controls the maximum possible grain-to-grain electric field. Understanding the finer details of regolith grain charging, conductive equilibrium, and dielectric breakdown will improve future numerical studies of space weathering and dust levitation on airless bodies.

A voice-actuated wind tunnel model leak checking system

NASA Technical Reports Server (NTRS)

Larson, William E.

1989-01-01

A computer program has been developed that improves the efficiency of wind tunnel model leak checking. The program uses a voice recognition unit to relay a technician's commands to the computer. The computer, after receiving a command, can respond to the technician via a voice response unit. Information about the model pressure orifice being checked is displayed on a gas-plasma terminal. On command, the program records up to 30 seconds of pressure data. After the recording is complete, the raw data and a straight line fit of the data are plotted on the terminal. This allows the technician to make a decision on the integrity of the orifice being checked. All results of the leak check program are stored in a database file that can be listed on the line printer for record keeping purposes or displayed on the terminal to help the technician find unchecked orifices. This program allows one technician to check a model for leaks instead of the two or three previously required.

Areal extent of petroleum-related compounds from a gasoline and diesel-fuel leak in ground water at a site in Yakima, Washington, 1984-89

USGS Publications Warehouse

Wagner, R.J.

1995-01-01

A gasoline and diesel-fuel leak was discovered in the early 1980's at a service station in Yakima, Washington, and an attempt to recover the flee-floating petroleum product was unsuccessful. From 1984 through 1989, data were collected from observation wells drilled near the site of the leak and from nearby domestic wells during three separate studies. Between February 1985 and November 1986, benzene, toluene, xylenes, and other soluble compounds of petroleum origin were found at concentrations that exceeded standards for drinking water in all samples from observation wells within 300 feet of the service station. These compounds also were found in smaller concentrations in some samples from domestic wells as far as 1,500 feet downgradient of the service station. Concentrations of these soluble compounds in ground-water samples collected in March 1989 had decreased, and areal distribution of the compounds was smaller than when monitoring began in 1984.

Robust Soft Textile Transfer Case for Contaminated Materials

DTIC Science & Technology

2017-08-28

least thirty-six pounds per square inch; remain leak -proof after a thirty foot drop when filled with water to at least a ninety-eight percent...shipping standards for use require a leak -proof seal without an allowance for pressure relief. While the container would likely never need to be re...after the insertion of the contents; be puncture Attorney Docket No. 300153 3 of 17 resistant; be leak -proof at a hydrostatic pressure of at

A proposed rationale and test methodology for establishment of acceptance criteria for vacuum integrity testing of pharmaceutical freeze dryers.

PubMed

Hardwick, Lisa M; Nail, Steven L; Jarman, James; Hasler, Kai; Hense, Thomas

2013-10-01

A scientific rationale is proposed for the establishment of acceptance criteria for leak rates in pharmaceutical freeze dryers. A method was developed to determine the quantity of air that could leak into any lyophilizer from the outside while still maintaining Class 100/Grade A microbial conditions. A lyophilizing product is assumed most vulnerable to microbial contamination during secondary drying, when mass transfer of water vapor from product to condenser is minimal. Using the void volume of the dryer, calculated from change in internal pressure when a known volume of air is introduced, and the potential maximum bioburden of the leaked air (based on measured values), calculations can determine the allowable leaked volume of air, the flow rate required to admit that volume in a given time frame, and the pressure rise that would result from the leak over a given testing period. For the dryers in this study, using worst-case air quality conditions, it was determined that a leak resulting in a pressure rise of 0.027 mbar over a 30 min period would allow the dryers to remain in secondary drying conditions for 62 h before the established action level of one colony forming unit for each cubic meter of air space would be reached. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of a Miniaturized and Portable Methane Analyzer for Natural Gas Leak Walking Surveys

NASA Astrophysics Data System (ADS)

Huang, Y. W.; Leen, J. B.; Gupta, M.; Baer, D. S.

2016-12-01

Traditional natural gas leak walking surveys have been conducted with devices that are based on technologies such as flame ionization detector (FID), IR-based spectrometer and IR camera. The sensitivity is typically on the ppm level. The low sensitivity means the device cannot pick up leaks far from it, and more time is spent surveying the area before pinpointing the leak location. A miniaturized methane analyzer has been developed to significantly improve the sensitivity of the device used in walking surveys to detect natural gas leaks at greater distance. ABB/LGR's patented Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) is utilized to offer rugged and highly sensitive methane detection in a portable package. The miniaturized package weighs 13.5 lb, with a 4-hour rechargeable battery inside. The precision of the analyzer for methane is 2 ppb at 1 second. The analyzer operates at 10 Hz and its flow response time is 3 seconds for measurements through a 1-meter long sampling wand to registering on the data stream. The data can be viewed in real-time on a tablet or a smartphone. The compact and simplified package of the methane analyzer allows for more efficient walking surveys. It also allows for other applications that require low-power, low-weight and a portable package. We present data from walking surveys to demonstrate its ability to detect methane leaks.

40 CFR 264.1065 - Reporting requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... identification number of each pump for which a leak was not repaired as required in § 264.1052 (c) and (d)(6... control device installed as required by § 264.1052, 264.1053, 264.1054, or 264.1055 exceeded or operated outside of the design specifications as defined in § 264.1064(e) and as indicated by the control device...

40 CFR 264.1065 - Reporting requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... identification number of each pump for which a leak was not repaired as required in § 264.1052 (c) and (d)(6... control device installed as required by § 264.1052, 264.1053, 264.1054, or 264.1055 exceeded or operated outside of the design specifications as defined in § 264.1064(e) and as indicated by the control device...

40 CFR 264.1065 - Reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... identification number of each pump for which a leak was not repaired as required in § 264.1052 (c) and (d)(6... control device installed as required by § 264.1052, 264.1053, 264.1054, or 264.1055 exceeded or operated outside of the design specifications as defined in § 264.1064(e) and as indicated by the control device...

40 CFR 264.1065 - Reporting requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... identification number of each pump for which a leak was not repaired as required in § 264.1052 (c) and (d)(6... control device installed as required by § 264.1052, 264.1053, 264.1054, or 264.1055 exceeded or operated outside of the design specifications as defined in § 264.1064(e) and as indicated by the control device...

40 CFR 264.1065 - Reporting requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... identification number of each pump for which a leak was not repaired as required in § 264.1052 (c) and (d)(6... control device installed as required by § 264.1052, 264.1053, 264.1054, or 264.1055 exceeded or operated outside of the design specifications as defined in § 264.1064(e) and as indicated by the control device...

40 CFR 63.175 - Quality improvement program for valves.

Code of Federal Regulations, 2010 CFR

2010-07-01

... improvement program for valves. (a) In Phase III, an owner or operator may elect to comply with one of the... use one of these alternative provisions to comply with the requirements of § 63.168(d)(1)(ii) of this... exceeds 2 percent leaking valves, and in such case, monthly monitoring will be required. (d) The following...

40 CFR 63.175 - Quality improvement program for valves.

Code of Federal Regulations, 2014 CFR

2014-07-01

... improvement program for valves. (a) In Phase III, an owner or operator may elect to comply with one of the... use one of these alternative provisions to comply with the requirements of § 63.168(d)(1)(ii) of this... exceeds 2 percent leaking valves, and in such case, monthly monitoring will be required. (d) The following...

LETTERS AND COMMENTS: Permeability measurements in undergraduate vacuum laboratories: a simple experiment using a He leak detector

NASA Astrophysics Data System (ADS)

dos Santos, J. M. F.; Veloso, J. F. C. A.; Monteiro, C. M. B.

2004-01-01

We describe a simple experiment intended for didactic laboratory vacuum classes of undergraduate courses, using a helium leak detector. The helium throughput flowing into the vacuum volume due to the permeability of materials can be taken as a real leak, which can be measured with the helium leak detector. The experiment allows students to perform actual measurements of helium permeability constants of different materials, and access the dependence of the helium permeability throughput on the material thickness, area and helium pressure differential. As an example, a set of measurements are presented for Kapton foils, exhibiting results that are in good agreement with those presented in the literature.

Extended Life Coolant Testing

DTIC Science & Technology

2016-06-06

between the corrosive water and the grease that was leaked into the system. In terms of corrosion, the third test still passed by not exceeding any of...length. While the results of testing showed little corrosion, some negative interactions with the corrosive water mixture were observed. 15...such as temperature, flow rate, or corrosive water concentration might have a larger impact on performance. UNCLASSIFIED UNCLASSIFIED vi

24 CFR 3285.605 - Fuel supply system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... designed for a pressure that is at least 7 inches of water column [4oz./in.2 or 0.25 psi] and not more than 14 inches of water column [8 oz./in.2 or 0.5 psi]. If gas from any supply source exceeds, or could... connector quick-disconnect. (c) Testing procedures. The gas system must be inspected and tested for leaks...

75 FR 54462 - Airworthiness Directives; Bombardier-Rotax GmbH 912 F Series and 912 S Series Reciprocating Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-08

... Airworthiness Directives; Bombardier-Rotax GmbH 912 F Series and 912 S Series Reciprocating Engines AGENCY... result in exceeding of the fuel pressure and might cause engine malfunction and/or massive fuel leakage... engine malfunction or a massive fuel leak. These conditions could cause loss of control of the airplane...

Utility of Objective Chest Tube Management After Pulmonary Resection Using a Digital Drainage System.

PubMed

Takamochi, Kazuya; Imashimizu, Kota; Fukui, Mariko; Maeyashiki, Tatsuo; Suzuki, Mikiko; Ueda, Takuya; Matsuzawa, Hironori; Hirayama, Shunki; Matsunaga, Takeshi; Oh, Shiaki; Suzuki, Kenji

2017-07-01

We sought to evaluate the clinical utility of chest tube management after pulmonary resection based on objective digital monitoring of pleural pressure and digital surveillance for air leaks. We prospectively recorded the perioperative data of 308 patients who underwent pulmonary resection between December 2013 and January 2016. We used information from a digital monitoring thoracic drainage system to measure peak air leakage during the first 24 hours after the operation, patterns of air leakage over the first 72 hours, and patterns of pleural pressure changes until the chest tubes were removed. There were 240 patients with lung cancer and 68 patients with other diseases. The operations included 49 wedge resections, 58 segmentectomies, and 201 lobectomies. A postoperative air leak was observed in 61 patients (20%). A prolonged air leak exceeding 20 mL/min lasting 5 days or more was observed in 18 patients (5.8%). Multivariate analysis of various perioperative factors showed forced expiratory volume in 1 second below 70%, patterns of air leakage, defined as exacerbating and remitting or without a trend toward improvement, and peak air leakage of 100 mL/min or more were significant positive predictors of prolonged air leak. Fluctuations in pleural pressure occurred just after the air leakage rate decreased to less than 20 mL/min. Digital monitoring of peak air leakage and patterns of air leakage were useful for predicting prolonged air leak after pulmonary resection. Information on the disappearance of air leak could be derived from the change in the rate of air leakage and from the increase in fluctuation of pleural pressure. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Postoperative esophageal leak management with the Polyflex esophageal stent.

PubMed

Freeman, Richard K; Ascioti, Anthony J; Wozniak, Thomas C

2007-02-01

Leak after esophageal anastomosis or perforation repair prolongs hospitalization, prevents oral hydration and nutrition, and can produce localized infection or sepsis. This investigation reviews our experience treating postoperative esophageal leaks with the Polyflex esophageal stent (Boston Scientific, Natick, Mass). Over a 30-month period, patients with a postoperative esophageal leak were treated with the Polyflex stent for leak occlusion. Leak occlusion was confirmed by means of esophagraphy. Patients were followed until their stent was removed and their esophageal leak had resolved. Twenty-one patients had 27 stents placed for leak occlusion after esophagectomy (n = 5), esophageal perforation (n = 5), surgical (n = 4) or endoscopic (n = 2) antireflux procedure, and esophageal diverticulectomy (n = 3) or myotomy (n = 2). The mean interval between surgical intervention and stent placement was 12 +/- 8 days (range, 3-31 days). Occlusion of the leak occurred in 20 patients. One patient experienced a dehiscence of the surgical esophageal perforation repair requiring esophageal diversion. Stent migration requiring repositioning (n = 3) or replacement (n = 4) occurred in 5 (24%) patients. Twenty (95%) stents were removed without residual leak (mean, 51 +/- 43 days; range, 15-175 days). One patient had a stricture after stent removal that required endoscopic dilatation. One patient in this series died. The Polyflex esophageal stent is an effective method for occluding a postoperative esophageal leak. It rapidly eliminates contamination of the mediastinum, pleura, and peritoneum; allows oral hydration and nutrition; and is easily removable. These stents also offer an appealing alternative to traditional esophageal diversion and subsequent reconstruction in patients with a persistent esophageal leak.

76 FR 39095 - Compatibility of Underground Storage Tank Systems With Biofuel Blends

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-05

... drinking water for nearly half of all Americans, the U.S. Environmental Protection Agency (EPA) regulates... components of the UST system, such as leak detection devices, sealants, and containment sumps, may not be... demonstration of compatibility. Some commenters suggested that EPA allow the National Work Group on Leak...

STS-113 workers search for oxygen leak

NASA Technical Reports Server (NTRS)

2002-01-01

KENNEDY SPACE CENTER, FLA. -- In the Payload Changeout Room, Launch Pad 39A, workers raise a platform toward the forward cargo bay area of Space Shuttle Endeavour to search for an oxygen leak. The launch of Endeavour on mission STS-113 was postponed Nov. 10, following the completion of tanking operations, due to higher than allowable oxygen levels in the orbiter's midbody. Workers will investigate the exact location and possible cause of the leak, and effect repairs. Launch has been tentatively set for no earlier than Nov. 18, between 7 and 11 p.m. EST.

STS-113 workers search for oxygen leak

NASA Technical Reports Server (NTRS)

2002-01-01

KENNEDY SPACE CENTER, FLA. -- Workers in the Payload Changeout Room, Launch Pad 39A, ride a platform toward the forward cargo bay area of Space Shuttle Endeavour to search for an oxygen leak. The launch of Endeavour on mission STS-113 was postponed Nov. 10, following the completion of tanking operations, due to higher than allowable oxygen levels in the orbiter's midbody. Workers will investigate the exact location and possible cause of the leak, and effect repairs. Launch has been tentatively set for no earlier than Nov. 18, between 7 and 11 p.m. EST.

STS-113 workers search for oxygen leak

NASA Technical Reports Server (NTRS)

2002-01-01

KENNEDY SPACE CENTER, FLA. -- Workers in the Payload Changeout Room, Launch Pad 39A, are on a platform in the forward cargo bay area of Space Shuttle Endeavour to search for an oxygen leak. The launch of Endeavour on mission STS-113 was postponed Nov. 10, following the completion of tanking operations, due to higher than allowable oxygen levels in the orbiter's midbody. Workers will investigate the exact location and possible cause of the leak, and effect repairs. Launch has been tentatively set for no earlier than Nov. 18, between 7 and 11 p.m. EST.

MASS SPECTROMETER LEAK

DOEpatents

Shields, W.R.

1960-10-18

An improved valve is described for precisely regulating the flow of a sample fluid to be analyzed, such as in a mass spectrometer, where a gas sample is allowed to "leak" into an evacuated region at a very low, controlled rate. The flow regulating valve controls minute flow of gases by allowing the gas to diffuse between two mating surfaces. The structure of the valve is such as to prevent the corrosive feed gas from contacting the bellows which is employed in the operation of the valve, thus preventing deterioration of the bellows.

Ultrafast dynamic computed tomography myelography for the precise identification of high-flow cerebrospinal fluid leaks caused by spiculated spinal osteophytes.

PubMed

Thielen, Kent R; Sillery, John C; Morris, Jonathan M; Hoxworth, Joseph M; Diehn, Felix E; Wald, John T; Rosebrock, Richard E; Yu, Lifeng; Luetmer, Patrick H

2015-03-01

Precise localization and understanding of the origin of spontaneous high-flow spinal CSF leaks is required prior to targeted treatment. This study demonstrates the utility of ultrafast dynamic CT myelography for the precise localization of high-flow CSF leaks caused by spiculated spinal osteophytes. This study reports a series of 14 patients with high-flow CSF leaks caused by spiculated spinal osteophytes who underwent ultrafast dynamic CT myelography between March 2009 and December 2010. There were 10 male and 4 female patients, with an average age of 49 years (range 37-74 years). The value of ultrafast dynamic CT myelography in depicting the CSF leak site was qualitatively assessed. In all 14 patients, ultrafast dynamic CT myelography was technically successful at precisely demonstrating the site of the CSF leak, the causative spiculated osteophyte piercing the dura, and the relationship of the implicated osteophyte to adjacent structures. Leak sites included 3 cervical, 11 thoracic, and 0 lumbar levels, with 86% of the leaks occurring from C-5 to T-7. Information obtained from the ultrafast dynamic CT myelogram was considered useful in all treated CSF leaks. Spinal osteophytes piercing the dura are a more frequent cause of high-flow CSF leaks than previously recognized. Ultrafast dynamic CT myelography adds value beyond standard dynamic myelography or digital subtraction myelography in the diagnosis and anatomical characterization of high-flow spinal CSF leaks caused by these osteophytes. This information allows for appropriate planning for percutaneous or surgical treatment.

Ultrasonic Detectors Safely Identify Dangerous, Costly Leaks

NASA Technical Reports Server (NTRS)

2013-01-01

In 1990, NASA grounded its space shuttle fleet. The reason: leaks detected in the hydrogen fuel systems of the Space Shuttles Atlantis and Columbia. Unless the sources of the leaks could be identified and fixed, the shuttles would not be safe to fly. To help locate the existing leaks and check for others, Kennedy Space Center engineers used portable ultrasonic detectors to scan the fuel systems. As a gas or liquid escapes from a leak, the resulting turbulence creates ultrasonic noise, explains Gary Mohr, president of Elmsford, New York-based UE Systems Inc., a long-time leader in ultrasonic detector technologies. "In lay terms, the leak is like a dog whistle, and the detector is like the dog ear." Because the ultrasound emissions from a leak are highly localized, they can be used not only to identify the presence of a leak but also to help pinpoint a leak s location. The NASA engineers employed UE s detectors to examine the shuttle fuel tanks and solid rocket boosters, but encountered difficulty with the devices limited range-certain areas of the shuttle proved difficult or unsafe to scan up close. To remedy the problem, the engineers created a long-range attachment for the detectors, similar to "a zoom lens on a camera," Mohr says. "If you are on the ground, and the leak is 50 feet away, the detector would now give you the same impression as if you were only 25 feet away." The enhancement also had the effect of reducing background noise, allowing for a clearer, more precise detection of a leak s location.

Hermetic Seal Leak Detection Apparatus with Variable Size Test Chamber

NASA Technical Reports Server (NTRS)

Kelley, Anthony R. (Inventor)

2015-01-01

The present invention is a versatile hermetic seal leak detection apparatus for testing hermetically sealed containers and devices for leaks without the need to create a custom or specially manufactured testing chamber conforming to the dimensions of the specific object under test. The size of the testing chamber may be mechanically adjusted by the novel use of bellows to reduce and optimize the amount of gas space in a test chamber which surrounds the hermetically sealed object under test. The present invention allows the size of the test chamber to be selectively adjusted during testing to provide an optimum test chamber gas space. The present invention may be further adapted to isolate and test specific portions of the hermetically sealed object under test for leaks.

Analytical study of the performance of a geomembrane leak detection system.

PubMed

Lugli, Francesco; Mahler, Claudio Fernando

2016-05-01

The electrical detection of leaks in geomembranes is a method that allows identifying leakage of contaminants in lined facilities (e.g. sanitary landfills, pollutant ponds, etc.). The procedure in the field involves placing electrodes above and below the geomembrane, to generate an electrical current, which in turn engenders an electric potential distribution in the protective layer (generally a clayey soil). The electric potential will be greater in areas with higher current density, i.e. near leaks. In this study, we combined models from the literature to carry out a parametric analysis to identify the variables that most influence the amplitude of the electrical signals produced by leaks. The basic hypothesis is that the electrical conduction phenomena in a liner system could be depicted by a direct current circuit. After determining the value of the current at the leak, we calculated the electric potential distribution according to the model of Darilek and Laine. This enabled analysing the sensitivity of the parameters, which can be useful in the design of landfills and facilitate the location of leaks. This study showed that geomembranes with low electrical resistance (owing to low thickness, low resistivity, or extensive area) can hinder the leak detection process. In contrast, low thickness and high resistivity of the protection layer magnify the leak signal. © The Author(s) 2016.

Vapor intrusion risk of lead scavengers 1,2-dibromoethane (EDB) and 1,2-dichloroethane (DCA).

PubMed

Ma, Jie; Li, Haiyan; Spiese, Richard; Wilson, John; Yan, Guangxu; Guo, Shaohui

2016-06-01

Vapor intrusion of synthetic fuel additives represented a critical yet still neglected problem at sites impacted by petroleum fuel releases. This study used an advanced numerical model to simulate the vapor intrusion risk of lead scavengers 1,2-dibromoethane (ethylene dibromide, EDB) and 1,2-dichloroethane (DCA) under different site conditions. We found that simulated EDB and DCA indoor air concentrations can exceed USEPA screening level (4.7 × 10(-3) μg/m(3) for EDB and 1.1 × 10(-1) μg/m(3) for DCA) if the source concentration is high enough (is still within the concentration range found at leaking UST site). To evaluate the chance that vapor intrusion of EDB might exceed the USEPA screening levels for indoor air, the simulation results were compared to the distribution of EDB at leaking UST sites in the US. If there is no degradation of EDB or only abiotic degradation of EDB, from 15% to 37% of leaking UST sites might exceed the USEPA screening level. This study supports the statements made by USEPA in the Petroleum Vapor Intrusion (PVI) Guidance that the screening criteria for petroleum hydrocarbon may not provide sufficient protectiveness for fuel releases containing EDB and DCA. Based on a thorough literature review, we also compiled previous published data on the EDB and DCA groundwater source concentrations and their degradation rates. These data are valuable in evaluating EDB and DCA vapor intrusion risk. In addition, a set of refined attenuation factors based on site-specific information (e.g., soil types, source depths, and degradation rates) were provided for establishing site-specific screening criteria for EDB and DCA. Overall, this study points out that lead scavengers EDB and DCA may cause vapor intrusion problems. As more field data of EDB and DCA become available, we recommend that USEPA consider including these data in the existing PVI database and possibly revising the PVI Guidance as necessary. Copyright © 2016 Elsevier Ltd. All rights reserved.

Local Leak Detection and Health Monitoring of Pressurized Tanks

NASA Technical Reports Server (NTRS)

Polzin, Kurt; Witherow, William; Korman, Valentin; Sinko, John; Hendrickson, Adam

2011-01-01

An optical gas-detection sensor safely monitors pressurized systems (such as cryogenic tanks) and distribution systems for leaks. This sensor system is a fiber-coupled, solid optical body interferometer that allows for the miniaturized sensing element of the device to be placed in the smallest of recesses, and measures a wide range of gas species and densities (leaks). The deflection of the fringe pattern is detected and recorded to yield the time-varying gas density in the gap. This technology can be used by manufacturers or storage facilities with toxic, hazardous, or explosive gases. The approach is to monitor the change in the index of refraction associated with low-level gas leaks into a vacuum environment. The completion of this work will provide NASA with an enabling capability to detect gas system leaks in space, and to verify that pressurized systems are in a safe (i.e. non-leaking) condition during manned docking and transit operations. By recording the output of the sensor, a time-history of the leak can be constructed to indicate its severity. Project risk is mitigated by having several interferometric geometries and detection techniques available, each potentially leveraging hardware and lessons learned to enhance detectability.

Presentation and surgical management of leaks after mini-gastric bypass for morbid obesity.

PubMed

Genser, Laurent; Carandina, Sergio; Tabbara, Malek; Torcivia, Adriana; Soprani, Antoine; Siksik, Jean-Michel; Cady, Jean

2016-02-01

Few data exist about the characteristics and management of enteric leaks after mini-gastric bypass (MGB). We aimed to describe the incidence, presentation, and surgical management of enteric leaks in patients who underwent laparoscopic MGB for morbid obesity. Private practice. An 8-year, 9-month retrospective chart review was performed on patients who had enteric leak requiring reoperation after MGB at a single institution. Thirty-five of 2321 patients were included. Ninety-seven percent had symptoms. Arterial hypertension and heavy smoking were predicting factors of leaks occurrence post-MGB (P<.01). Enteric leak was diagnosed by systematic upper gastrointestinal series in 4 pts (11.4%) and by computed tomography with oral water soluble contrast in 4 of 31 pts (13%). In the other 27 patients, diagnosis of the leak was made intraoperatively. Eleven patients (32%) had leak arising from the gastric stapler line (type 1), 4 (11%) from the gastrojejunal anastomosis (type 2), and 20 (57%) from undetermined origin. The most common presentation was intra-abdominal abscess in type 1 and leaks of undetermined origin and generalized peritonitis in type 2. One third of the patients who underwent reoperation developed well-drained chronic fistula into the irrigation-drainage system, with complete healing in all patients without any further procedure. The mean hospital stay was 19 days with no mortality reported. Enteric leak leading to intra-abdominal sepsis post-MGB is rare (1.5%) An operative aggressive management based on clinical symptoms is the treatment of choice allowing no postoperative leak-related mortality and complete healing. Copyright © 2016 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

Combined Endoscopic Transorbital and Endonasal Repair of High Flow Orbital Apex/Middle Fossa Cerebrospinal Fluid Leak with a Nasoseptal Flap.

PubMed

Lucke-Wold, Brandon; Mendez, Gustavo; Cua, David; Akins, Paul; Gillham, Haley; Ciporen, Jeremy

2018-01-01

High flow orbital apex or middle fossa cerebrospinal fluid (CSF) leaks can be life threatening and complex to repair. These leaks associated with large dural defects are most commonly repaired with an open temporalis muscle patch or free flaps, but these flaps do not always stop the leak. A 65-year-old patient presented two years after orbital exenteration and radiation for squamous cell carcinoma. He developed multi-organism meningitis and pneumocephalus secondary to a large high-flow orbital apex/middle fossa CSF leak. To repair the leak, a combined endoscopic transorbital/endonasal approach with pedicled nasospetal flap and dermis fat graft was used. We describe the unique endoscopic technique that was used to treat the life threatening high flow orbital apex/middle fossa CSF leak. The technique allowed the use of the transposed pedicled flap, which is an alternative to the free flap in controlling CSF leak. Cisternogram post-operatively and clinical exam confirmed resolution of CSF leak. Although a critically ill patient at admission with a modified Rankin scale (MRS) of 5, he was discharged home on continued IV antibiotic therapy with a MRS of 3. Endoscopic evaluation at three months after treatment showed the effectiveness of the flap and he continued to improve clinically. This is the first case to describe a combined endoscopic transorbital and endonasal repair of high flow orbital apex/middle fossa CSF leak with a pedicled nasoseptal flap. These techniques can be utilized during initial reconstruction after orbital exenteration or as a salvage flap.

Annular Air Leaks in a liquid hydrogen storage tank

NASA Astrophysics Data System (ADS)

Krenn, AG; Youngquist, RC; Starr, SO

2017-12-01

Large liquid hydrogen (LH2) storage tanks are vital infrastructure for NASA, the DOD, and industrial users. Over time, air may leak into the evacuated, perlite filled annular region of these tanks. Once inside, the extremely low temperatures will cause most of the air to freeze. If a significant mass of air is allowed to accumulate, severe damage can result from nominal draining operations. Collection of liquid air on the outer shell may chill it below its ductility range, resulting in fracture. Testing and analysis to quantify the thermal conductivity of perlite that has nitrogen frozen into its interstitial spaces and to determine the void fraction of frozen nitrogen within a perlite/frozen nitrogen mixture is presented. General equations to evaluate methods for removing frozen air, while avoiding fracture, are developed. A hypothetical leak is imposed on an existing tank geometry and a full analysis of that leak is detailed. This analysis includes a thermal model of the tank and a time-to-failure calculation. Approaches to safely remove the frozen air are analyzed, leading to the conclusion that the most feasible approach is to allow the frozen air to melt and to use a water stream to prevent the outer shell from chilling.

Field Trial of an Aerosol-Based Enclosure Sealing Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrington, Curtis; Springer, David

2015-09-01

This report presents the results from several demonstrations of a new method for sealing building envelope air leaks using an aerosol sealing process developed by the Western Cooling Efficiency Center at UC Davis. The process involves pressurizing a building while applying an aerosol sealant to the interior. As air escapes through leaks in the building envelope, the aerosol particles are transported to the leaks where they collect and form a seal that blocks the leak. Standard blower door technology is used to facilitate the building pressurization, which allows the installer to track the sealing progress during the installation and automaticallymore » verify the final building tightness. Each aerosol envelope sealing installation was performed after drywall was installed and taped, and the process did not appear to interrupt the construction schedule or interfere with other trades working in the homes. The labor needed to physically seal bulk air leaks in typical construction will not be replaced by this technology.« less

The ISS 2B PVTCS Ammonia Leak: An Operational History

NASA Technical Reports Server (NTRS)

Vareha, Anthony

2014-01-01

In 2006, the Photovoltaic Thermal Control System (PVTCS) for the International Space Station's 2B power channel began leaking ammonia at a rate of approximately 1.5lbm/year (out of a starting approximately 53lbm system ammonia mass). Initially, the operations strategy was "feed the leak," a strategy successfully put into action via Extra Vehicular Activity during the STS-134 mission. During this mission the system was topped off with ammonia piped over from a separate thermal control system. This recharge was to have allowed for continued power channel operation into 2014 or 2015, at which point another EVA would have been required. Without these periodic EVAs to refill the 2B coolant system, the channel would eventually leak enough fluid as to risk pump cavitation and system failure, resulting in the loss of the 2B power channel - the most critical of the Space Station's 8 power channels. In mid-2012, the leak rate increased to approximately 5lbm/year. Once discovered, an EVA was planned and executed within a 5 week timeframe to drastically alter the architecture of the PVTCS via connection to a dormant thermal control system not intended to be utilized as anything other than spare components. The purpose of this rerouting of the TCS was to increase system volume and to isolate the photovoltaic radiator, thought to be the likely leak source. This EVA was successfully executed on November 1st, 2012 and left the 2B PVTCS in a configuration where the system was now being adequately cooled via a totally different radiator than what the system was designed to utilize. Unfortunately, data monitoring over the next several months showed that the isolated radiator was not leaking, and the system itself continued to leak steadily until May 9th, 2013. It was on this day that the ISS crew noticed the visible presence of ammonia crystals escaping from the 2B channel's truss segment, signifying a rapid acceleration of the leak from 5lbm/year to 5lbm/day. Within 48 hours of the crew noticing the leak, an EVA was in progress to replace the coolant pump - the only other replaceable leak source. This paper will explore the management of the 2B PVTCS leak from the operations perspective. It will discuss the methodology of performing the STS-134 refill, the considerations and contingency plans which went into the architectural overhaul of the system in 2012, and the unprecedented effort which went into the EVA response to the visible leak of May 2013. In particular the paper will focus on the techniques utilized by flight controllers to monitor the system health and to respond to such instances as the rapid May 2013 leak by putting the electrical system in a safe configuration for loss of cooling, and will use recorded telemetry of these events to describe system response to EVA crew and ground actions. It will discuss the innovative design for redundancy of the integrated truss structure's cooling systems which allowed for this leak to be managed with minimal impact to other ISS operations and electrical services, contrasted against the real unintended operations consequences of utilizing the flexibility of the spacecraft's design in this manner. The paper will discuss how the training of the crew and flight controller personnel has adapted to the changing architecture of the power system and the unpredictable nature of the 2B leak.

Comparing Natural Gas Leakage Detection Technologies Using an Open-Source "Virtual Gas Field" Simulator.

PubMed

Kemp, Chandler E; Ravikumar, Arvind P; Brandt, Adam R

2016-04-19

We present a tool for modeling the performance of methane leak detection and repair programs that can be used to evaluate the effectiveness of detection technologies and proposed mitigation policies. The tool uses a two-state Markov model to simulate the evolution of methane leakage from an artificial natural gas field. Leaks are created stochastically, drawing from the current understanding of the frequency and size distributions at production facilities. Various leak detection and repair programs can be simulated to determine the rate at which each would identify and repair leaks. Integrating the methane leakage over time enables a meaningful comparison between technologies, using both economic and environmental metrics. We simulate four existing or proposed detection technologies: flame ionization detection, manual infrared camera, automated infrared drone, and distributed detectors. Comparing these four technologies, we found that over 80% of simulated leakage could be mitigated with a positive net present value, although the maximum benefit is realized by selectively targeting larger leaks. Our results show that low-cost leak detection programs can rely on high-cost technology, as long as it is applied in a way that allows for rapid detection of large leaks. Any strategy to reduce leakage should require a careful consideration of the differences between low-cost technologies and low-cost programs.

Methane Leaks from Natural Gas Systems Follow Extreme Distributions.

PubMed

Brandt, Adam R; Heath, Garvin A; Cooley, Daniel

2016-11-15

Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH 4 ) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ∼15 000 measurements from 18 prior studies, we show that all available natural gas leakage data sets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the total leakage volume. While prior studies used log-normal model distributions, we show that log-normal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH 4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of data sets to increase sample size is not recommended due to apparent deviation between sampled populations. Understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.

Methane Leaks from Natural Gas Systems Follow Extreme Distributions

DOE PAGES

Brandt, Adam R.; Heath, Garvin A.; Cooley, Daniel

2016-10-14

Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH 4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ~15,000 measurements from 18 prior studies, we show that all available natural gas leakage datasets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of themore » total leakage volume. While prior studies used lognormal model distributions, we show that lognormal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH 4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of datasets to increase sample size is not recommended due to apparent deviation between sampled populations. Finally, understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.« less

Methane Leaks from Natural Gas Systems Follow Extreme Distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, Adam R.; Heath, Garvin A.; Cooley, Daniel

Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH 4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ~15,000 measurements from 18 prior studies, we show that all available natural gas leakage datasets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of themore » total leakage volume. While prior studies used lognormal model distributions, we show that lognormal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH 4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of datasets to increase sample size is not recommended due to apparent deviation between sampled populations. Finally, understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.« less

A perspective on cost-effectiveness of greenhouse gas reduction solutions in water distribution systems

NASA Astrophysics Data System (ADS)

Hendrickson, Thomas P.; Horvath, Arpad

2014-01-01

Water distribution systems (WDSs) face great challenges as aging infrastructures require significant investments in rehabilitation, replacement, and expansion. Reducing environmental impacts as WDSs develop is essential for utility managers and policy makers. This study quantifies the existing greenhouse gas (GHG) footprint of common WDS elements using life-cycle assessment (LCA) while identifying the greatest opportunities for emission reduction. This study addresses oversights of the related literature, which fails to capture several WDS elements and to provide detailed life-cycle inventories. The life-cycle inventory results for a US case study utility reveal that 81% of GHGs are from pumping energy, where a large portion of these emissions are a result of distribution leaks, which account for 270 billion l of water losses daily in the United States. Pipe replacement scheduling is analyzed from an environmental perspective where, through incorporating leak impacts, a tool reveals that optimal replacement is no more than 20 years, which is in contrast to the US average of 200 years. Carbon abatement costs (CACs) are calculated for different leak reduction scenarios for the case utility that range from -130 to 35 t-1 CO2(eq). Including life-cycle modeling in evaluating pipe materials identified polyvinyl chloride (PVC) and cement-lined ductile iron (DICL) as the Pareto efficient options, however; utilizing PVC presents human health risks. The model developed for the case utility is applied to California and Texas to determine the CACs of reducing leaks to 5% of distributed water. For California, annual GHG savings from reducing leaks alone (3.4 million tons of CO2(eq)) are found to exceed California Air Resources Board’s estimate for energy efficiency improvements in the state’s water infrastructure.

The International Space Station 2B Photovoltaic Thermal Control System (PVTCS) Leak: An Operational History

NASA Technical Reports Server (NTRS)

Vareha, Anthony N.

2014-01-01

As early as 2004, the Photovoltaic Thermal Control System (PVTCS) for the International Space Station's 2B electrical power channel began slowly leaking ammonia overboard. Initially, the operations strategy was "feed the leak," a strategy successfully put into action via Extra Vehicular Activity (EVA) during the STS-134 Space Shuttle mission. This recharge was to have allowed for continued power channel operation into 2014 or 2015, at which point another EVA would have been required. In mid-2012, the leak rate increased from 1.5lbm/year to approximately 5lbm/year. As a result, an EVA was planned and executed within a 5 week timeframe to drastically alter the architecture of the PVTCS via connection to an adjacent dormant thermal control system. This EVA, US EVA 20, was successfully executed on November 1, 2012 and left the 2B PVTCS in a configuration where the system was now being adequately cooled via a different radiator than what the system was designed to utilize. Data monitoring over the next several months showed that the isolated radiator had not been leaking, and the system itself continued to leak steadily until May 9th, 2013. It was on this day that the ISS crew noticed the visible presence of ammonia crystals escaping from the 2B channel's truss segment, signifying a rapid acceleration of the leak from 5lbm/year to 5lbm/day. Within 48 hours of the crew noticing the leak, US EVA 21 was in progress to replace the coolant pump - the only remaining replaceable leak source. This was successful, and telemetry monitoring has shown that indeed the coolant pump was the leak source and was thus isolated from the running 2B PVTCS. This paper will explore the management of the 2B PVTCS leak from the operations perspective.

Chip-scale hermetic feedthroughs for implantable bionics.

PubMed

Guenther, Thomas; Dodds, Christopher W D; Lovell, Nigel H; Suaning, Gregg J

2011-01-01

Most implantable medical devices such as cochlear implants and visual prostheses require protection of the stimulating electronics. This is achieved by way of a hermetic feedthrough system which typically features three important attributes: biocompatibility with the human body, device hermeticity and density of feedthrough conductors. On the quest for building a visual neuroprosthesis, a high number of stimulating channels is required. This has encouraged new technologies with higher rates of production yield and further miniaturization. An Al(2)O(3) based feedthrough system has been developed comprising up to 20 platinum feedthroughs per square millimeter. Ceramics substrates are shown to have leak rates below 1 × 10(-12) atm × cc/s, thus exceeding the resolution limits of most commercially available leak detectors. A sheet resistance of 0.05 Ω can be achieved. This paper describes the design, fabrication process and hermeticity testing of high density feedthroughs for use in neuroprosthetic implants.

Leaking in history space: A way to analyze systems subjected to arbitrary driving

NASA Astrophysics Data System (ADS)

Kaszás, Bálint; Feudel, Ulrike; Tél, Tamás

2018-03-01

Our aim is to unfold phase space structures underlying systems with a drift in their parameters. Such systems are non-autonomous and belong to the class of non-periodically driven systems where the traditional theory of chaos (based e.g., on periodic orbits) does not hold. We demonstrate that even such systems possess an underlying topological horseshoe-like structure at least for a finite period of time. This result is based on a specifically developed method which allows to compute the corresponding time-dependent stable and unstable foliations. These structures can be made visible by prescribing a certain type of history for an ensemble of trajectories in phase space and by analyzing the trajectories fulfilling this constraint. The process can be considered as a leaking in history space—a generalization of traditional leaking, a method that has become widespread in traditional chaotic systems, to leaks depending on time.

Importance of limiting hohlraum leaks at cryogenic temperatures on NIF targets

DOE PAGES

Bhandarkar, Suhas; Teslich, Nick; Haid, Ben; ...

2017-08-18

Inertial confinement fusion targets are complex systems designed to allow fine control of temperature and pressure for making precise spherical ice layers of hydrogen isotopes at cryogenic temperatures. We discuss the various technical considerations for a maximum leak rate based on heat load considerations. This maximum flow rate turns out to bemore » $$5\\times 10^{-6}$$ standard cc per second, which can be caused by an orifice less than half a micron in diameter. This makes the identification of the location and resolution of the leak a significant challenge. To illustrate this, we showcase one example of a peculiar failure mode that appeared suddenly but persisted whereby target production yield was severely lowered. Identification of the leak source and the root cause requires very careful analysis of multiple thermomechanical aspects to ensure that the end solution is indeed the right remedy and is robust.« less

Testing of heat exchangers in membrane oxygenators using air pressure.

PubMed

Hamilton, Carole; Stein, Jutta; Seidler, Rainer; Kind, Robert; Beck, Karin; Tosok, Jürgen; Upterfofel, Jörg

2006-03-01

All heat exchangers (HE) in membrane oxygenators are tested by the manufacturer for water leaks during the production phase. However, for safety reasons, it is highly recommended that HEs be tested again before clinical use. The most common method is to attach the heater-cooler to the HE and allow the water to recirculate for at least 10 min, during which time a water leak should be evident. To improve the detection of water leaks, a test was devised using a pressure manometer with an integrated bulb used to pressurize the HE with air. The cardiopulmonary bypass system is set up as per protocol. A pressure manometer adapted to a 1/2" tubing is connected to the water inlet side of the oxygenator. The water outlet side is blocked with a short piece of 1/2" deadend tubing. The HE is pressurized with 250 mmHg for at least 30 sec and observed for any drop. Over the last 2 years, only one oxygenator has been detected with a water leak in which the air-method leaktest was performed. This unit was sent back to the manufacturer who confirmed the failure. Even though the incidence of water leaks is very low, it does occur and it is, therefore, important that all HEs are tested before they are used clinically. This method of using a pressure manometer offers many advantages, as the HE can be tested outside of the operating room (OR), allowing earlier testing of the oxygenator, no water contact is necessary, and it is simple, easy and quick to perform.

Fugitive Methane Gas Emission Monitoring in oil and gas industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, Levente

Identifying fugitive methane leaks allow optimization of the extraction process, can extend gas extraction equipment lifetime, and eliminate hazardous work conditions. We demonstrate a wireless sensor network based on cost effective and robust chemi-resistive methane sensors combined with real time analytics to identify leaks from 2 scfh to 10000 scfh. The chemi-resistive sensors were validated for sensitivity better than 1 ppm of methane plume detection. The real time chemical sensor and wind data is integrated into an inversion models to identify the location and the magnitude of the methane leak. This integrated solution can be deployed in outdoor environment formore » long term monitoring of chemical plumes.« less

Two-stream Convolutional Neural Network for Methane Emissions Quantification

NASA Astrophysics Data System (ADS)

Wang, J.; Ravikumar, A. P.; McGuire, M.; Bell, C.; Tchapmi, L. P.; Brandt, A. R.

2017-12-01

Methane, a key component of natural gas, has a 25x higher global warming potential than carbon dioxide on a 100-year basis. Accurately monitoring and mitigating methane emissions require cost-effective detection and quantification technologies. Optical gas imaging, one of the most commonly used leak detection technology, adopted by Environmental Protection Agency, cannot estimate leak-sizes. In this work, we harness advances in computer science to allow for rapid and automatic leak quantification. Particularly, we utilize two-stream deep Convolutional Networks (ConvNets) to estimate leak-size by capturing complementary spatial information from still plume frames, and temporal information from plume motion between frames. We build large leak datasets for training and evaluating purposes by collecting about 20 videos (i.e. 397,400 frames) of leaks. The videos were recorded at six distances from the source, covering 10 -60 ft. Leak sources included natural gas well-heads, separators, and tanks. All frames were labeled with a true leak size, which has eight levels ranging from 0 to 140 MCFH. Preliminary analysis shows that two-stream ConvNets provides significant accuracy advantage over single steam ConvNets. Spatial stream ConvNet can achieve an accuracy of 65.2%, by extracting important features, including texture, plume area, and pattern. Temporal stream, fed by the results of optical flow analysis, results in an accuracy of 58.3%. The integration of the two-stream ConvNets gives a combined accuracy of 77.6%. For future work, we will split the training and testing datasets in distinct ways in order to test the generalization of the algorithm for different leak sources. Several analytic metrics, including confusion matrix and visualization of key features, will be used to understand accuracy rates and occurrences of false positives. The quantification algorithm can help to find and fix super-emitters, and improve the cost-effectiveness of leak detection and repair programs.

Development of a new seal for use on large openings of pressurized spacecraft

NASA Technical Reports Server (NTRS)

Weddendorf, B.

1994-01-01

The goal of this project was to design, build, and test an example of the seal invented by the author for use on Space Station Freedom and patented in 1991. The seal features a metallic spring core and replaceable elastomeric sealing elements. The metallic spring is designed to retain the sealing force of the elastomeric element against both sides of face seal gland for any specified amount of waviness or separation of the glands. A seal able to tolerate at least 1.3 mm (0.05 in) of flange distortion or separation and a test fixture of this seal which allowed direct comparison testing of O-rings were built. These designs were tested to compare leakage at different amounts of flange deflection. Results of the testing show the development seal exceeded its requirement to seal 1.3 mm of flange separation by 1 mm. This compared with the O-ring leakage, increasing dramatically at 0.5 mm of separation. The development seal also leaked at a lower rate than the O-ring seals in all tests.

Application of the differentiation process into the correlation-based leak detection in urban pipeline networks

NASA Astrophysics Data System (ADS)

Gao, Yan; Liu, Yuyou; Ma, Yifan; Cheng, Xiaobin; Yang, Jun

2018-11-01

One major challenge currently facing pipeline networks across the world is the improvement of leak detection technologies in urban environments. There is an imperative to locate accurately leaks in buried water pipes to avoid serious environmental, social and economic consequences. Much attention has been paid to time delay estimation (TDE) in determining the position of a leak by utilising cross-correlation, which has been proven to be effective with varying degrees of success over the past half century. Previous research in published literature has demonstrated the effectiveness of the pre-whitening process for accentuating the peak in the cross-correlation associated with the time delay. This paper is concerned with the implementation of the differentiation process for TDE, with particular focus on the problem of determining a leak in pipelines by means of pipe pressure measurements. Rather than the pre-whitening operation, the proposed cross-correlation via the differentiation process, termed here DIF, changes the characteristics of the pipe system so that the pipe effectively acts as a band-pass filter. This method has the potential to eliminate some ambiguity caused by the interference at low frequencies and to allow more high frequency information to pass. Given an appropriate differentiation order, a more pronounced and reliable peak is obtained in the cross-correlation result. The use of differentiation process may provide a viable cross-correlation method suited to water leak detection. Its performance in relation to leak detection is further compared to the basic cross-correlation and pre-whitening methods for TDE in detecting a leak from actual PVC water pipes. Experimental results are presented to show an additional property of the DIF compensating for the resonance effects that may exist in cross-spectral density measurements, and hence better performance for TDE.

Vendors unveil one-step fugitive emissions monitoring, management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walter, M.

1995-04-01

An alliance of manufacturers has developed a ``single-source solution`` for fugitive emissions monitoring. The LeakTracker{trademark} system combines barcode scans, and vapor detection and data collection capabilities to help companies comply with leak detection and repair requirements as mandated by the Environmental Protection Agency`s Method 21 guidelines. LeakTracker doubles productivity and helps eliminate human-error factors associated with fugitive emissions monitoring. Two-person teams, clipboard-and-pencil data entry, and manual data transcription are eliminated. By automating the process and integrating all components, a technician can monitor 500 points daily following Method 21 guidelines, compared to about 250 readings per day using other systems. LeakTrackermore » includes a handheld workstation, sampling probe and laser-scan barcode reader that fit in a vest worn by a field technician. The technician points the workstation toward a barcode tag and pulls the trigger, which initiates a barcode read and automatically records the time, date and location. While the detachable probe ``sniffs`` for emissions, an analyzer interface module converts the gas detection signal from analog to digital format, allowing data to be recorded by the workstation. LeakTracker has an accuracy rate of 1 part per million.« less

ISS Ammonia Leak Detection Through X-Ray Fluorescence

NASA Technical Reports Server (NTRS)

Camp, Jordan; Barthelmy, Scott; Skinner, Gerry

2013-01-01

Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk. A proposed ISS astrophysics instrument, the Lobster X-Ray Monitor, can be used to detect and localize ISS ammonia leaks. Based on the optical design of the eye of its namesake crustacean, the Lobster detector gives simultaneously large field of view and good position resolution. The leak detection principle is that the nitrogen in the leaking ammonia will be ionized by X-rays from the Sun, and then emit its own characteristic Xray signal. The Lobster instrument, nominally facing zenith for its astrophysics observations, can be periodically pointed towards the ISS radiator panels and some sections of the transport lines to detect and localize the characteristic X-rays from the ammonia leaks. Another possibility is to use the ISS robot arm to grab the Lobster instrument and scan it across the transport lines and radiator panels. In this case the leak detection can be made more sensitive by including a focused 100-microampere electron beam to stimulate X-ray emission from the leaking nitrogen. Laboratory studies have shown that either approach can be used to locate ammonia leaks at the level of 0.1 kg/day, a threshold rate of concern for the ISS. The Lobster instrument uses two main components: (1) a microchannel plate optic (also known as a Lobster optic) that focuses the X-rays and directs them to the focal plane, and (2) a CCD (charge coupled device) focal plane detector that reads out the position and energy of the X-rays, allowing a determination of the leak location. The effective area of the detection system is approximately 2 cm(exp2) at 1 keV. The Lobster astrophysics instrument, designed for monitoring the sky for Xray transients, gives high sensitivity along with large field of view (30×30deg) and good spatial resolution (1 arc min). This offers a significant benefit for detecting ISS ammonia leaks, since the goal is to localize small leaks as efficiently as possible.

Electrical detection of liquid lithium leaks from pipe joints.

PubMed

Schwartz, J A; Jaworski, M A; Mehl, J; Kaita, R; Mozulay, R

2014-11-01

A test stand for flowing liquid lithium is under construction at Princeton Plasma Physics Laboratory. As liquid lithium reacts with atmospheric gases and water, an electrical interlock system for detecting leaks and safely shutting down the apparatus has been constructed. A defense in depth strategy is taken to minimize the risk and impact of potential leaks. Each demountable joint is diagnosed with a cylindrical copper shell electrically isolated from the loop. By monitoring the electrical resistance between the pipe and the copper shell, a leak of (conductive) liquid lithium can be detected. Any resistance of less than 2 kΩ trips a relay, shutting off power to the heaters and pump. The system has been successfully tested with liquid gallium as a surrogate liquid metal. The circuit features an extensible number of channels to allow for future expansion of the loop. To ease diagnosis of faults, the status of each channel is shown with an analog front panel LED, and monitored and logged digitally by LabVIEW.

Verification of International Space Station Component Leak Rates by Helium Accumulation Method

NASA Technical Reports Server (NTRS)

Underwood, Steve D.; Smith, Sherry L.

2003-01-01

Discovery of leakage on several International Space Station U.S. Laboratory Module ammonia system quick disconnects (QDs) led to the need for a process to quantify total leakage without removing the QDs from the system. An innovative solution was proposed allowing quantitative leak rate measurement at ambient external pressure without QD removal. The method utilizes a helium mass spectrometer configured in the detector probe mode to determine helium leak rates inside a containment hood installed on the test component. The method was validated through extensive developmental testing. Test results showed the method was viable, accurate and repeatable for a wide range of leak rates. The accumulation method has been accepted by NASA and is currently being used by Boeing Huntsville, Boeing Kennedy Space Center and Boeing Johnson Space Center to test welds and valves and will be used by Alenia to test the Cupola. The method has been used in place of more expensive vacuum chamber testing which requires removing the test component from the system.

Normally-Closed Zero-Leak Valve with Magnetostrictive Actuator

NASA Technical Reports Server (NTRS)

Ramspacher, Daniel J. (Inventor); Richard, James A. (Inventor)

2017-01-01

A non-pyrotechnic, normally-closed, zero-leak valve is a replacement for the pyrovalve used for both in-space and launch vehicle applications. The valve utilizes a magnetostrictive alloy for actuation, rather than pyrotechnic charges. The alloy, such as Terfenol-D, experiences magnetostriction, i.e. a gross elongation, when exposed to a magnetic field. This elongation fractures a parent metal seal, allowing fluid flow through the valve. The required magnetic field is generated by redundant coils that are isolated from the working fluid.

Identifying Patients at Higher Risk of Prolonged Air Leak After Lung Resection.

PubMed

Gilbert, Sebastien; Maghera, Sonam; Seely, Andrew J; Maziak, Donna E; Shamji, Farid M; Sundaresan, Sudhir R; Villeneuve, Patrick J

2016-11-01

Predictive models of prolonged air leak have relied on information not always available preoperatively (eg, extent of resection, pleural adhesions). Our objective was to construct a model to identify patients at increased risk of prolonged air leak using preoperative factors exclusively. From 2012 to 2014, data on consecutive patients undergoing pulmonary resection were collected prospectively. Prolonged air leak was defined as lasting longer than 7 days and requiring hospitalization. Factors associated with the primary outcome (p < 0.2) were included in a multivariate model. Regression coefficients were used to develop a weighted risk score for prolonged air leak. Of 225 patients, 8% (18/225) experienced a prolonged air leak. Male gender (p = 0.08), smoking history (p = 0.03), body mass index (BMI) 25 or below (p < 0.01), Medical Research Council (MRC) dyspnea score above 1 (p = 0.06), and diffusion capacity for carbon monoxide below 80% (Dlco) (p = 0.01) were selected for inclusion in the final model. Weighted scores were male gender (1 point), BMI 25 or below (0.5 point), smoker (2 points), Dlco% below 80% (2 points), and MRC dyspnea score above 1 (1 point). The area under the receiver operating characteristic curve was 0.8 (95% confidence interval [CI] = 0.7 to 0.9]. An air leak score above 4 points offered the best combination of sensitivity (83% [95% CI = 58 to 96]) and specificity (65% [95% CI = 58 to 71]). A subgroup of lung resection patients at higher risk for a prolonged air leak can be effectively identified with the use of widely available, preoperative factors. The proposed scoring system is simple, is clinically relevant to the informed consent, and allows preoperative patient selection for interventions to reduce the risk of prolonged air leak. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Leveraging Social Norms to Improve Leak Resolution Outcomes Across Meter Classes:

NASA Astrophysics Data System (ADS)

Holleran, W.

2016-12-01

Over the past decade, utilities, governments, businesses, and nonprofits have come to realize that more than just financial considerations and information drive behavior. Social and psychological factors also play a significant role in shaping consumers' decisions and behaviors around resource use. Stakeholders have consequently turned their interest to behavioral science, a multidisciplinary field that draws from psychology, sociology, public health, and behavioral economics to explain the complex mechanisms that shape human behavior. When used strategically, behavioral science holds the potential to drive down resource use, drive up profits, and generate measurable gains in conservation and efficiency. WaterSmart will present on how the water sector can employ behavioral science to nudge residential rate-payers to use water more efficiently and help them save money. Utilities can use behavioral science to influence people's reaction to leaks. 5% of Single Family Residential (SFR) metered water use can be attributed to leaks. This value potentially skews even higher for MultiFamily (MF) and Commercial accounts given that it can get lost in the noise of daily consumption. Existing leak detection algorithms in the market are not sophisticated enough to detect leaks for a MF or Commercial property. Leveraging data from utilities on known leak events at MF and Commercial buildings allowed WaterSmart to train a machine learning model to identify key features in the load shape and accurately detect these types of water use events. The outcome of the model is a leak amount and confidence level for each irregular usage event. The model also incorporates record feedback from users on the type of leak event, and the accuracy of the alert. When WaterSmart leverages this data model with social norms messaging, we've been able to improve water demand management for MF and Commercial properties. Experiences from leak detection and resolution in the SFR space will also be discussed.

Non-invasive ventilation: evaluation of CO2 washout by intentional leaking in three recent oronasal masks. A pilot study.

PubMed

Medrinal, C; Prieur, G; Contal, O; Villiot-Danger, E; Doyle, C; Reychler, G; Quieffin, J

2015-05-01

Many types of interfaces with intentional leaks exist for Non Invasive Ventilation. The purpose of intentional leaks is to remove CO2 from the interface, however the calibration does not allow a sufficiently large flow and rebreathing of CO2 can occur. The aim of this study was to compare the CO2 rinsing capacities of three new generation oronasal masks with intentional leaks (A: Quattro®, [Resmed]; B: Amara® [Respironics]; C: Forma® [Fisher&Paykel]) in healthy subjects. Seventeen healthy volunteers were included in this prospective cross-sectional, randomized, double-blinded trial. Each subject underwent ventilation with a home ventilator (IPAP: 14 cmH2O; EPAP: 4 cmH2O) with each mask consecutively. Transcutaneous capnography (PtcCO2) recordings were carried out throughout the trial and ventilator data (tidal volume, respiratory rate, minute ventilation and unintentional leaks) were also analyzed. Mask comfort was assessed using a visual analog scale (0 to 10). The results showed no differences in PtcCO2 between masks (P=0.82). There were no significant differences in respiratory parameters (tidal volume, P=0.79; respiratory rate, P=0.65; minute ventilation, P=0.12) between masks. The rate of unintentional leaks were significantly lower for Mask A (P=0.016). Subjects rated Mask A and Mask C as more comfortable than Mask B (P=0.041). There was no effect of mask on PtcCO2 in healthy subjects. The mask with the highest comfort rating had not the lowest rate of unintentional leaks.

Septotomy and Balloon Dilation to Treat Chronic Leak After Sleeve Gastrectomy: Technical Principles.

PubMed

Campos, Josemberg Marins; Ferreira, Flávio Coelho; Teixeira, André F; Lima, Jones Silva; Moon, Rena C; D'Assunção, Marco Aurélio; Neto, Manoel Galvão

2016-08-01

Chronic leaks after laparoscopic sleeve gastrectomy (LSG) are often difficult to treat by endoscopy metallic stent. Septotomy has been indicated as an effective procedure, but the technical aspects have not been detailed in previous publications (Campos JM, Siqueira LT, Ferraz AA, et al., J Am Coll Surg 204(4):711, 2007; Baretta G, Campos J, Correia S, et al., Surg Endosc 29(7):1714-20, 2015; Campos JM, Pereira EF, Evangelista LF, et al., Obes Surg 21(10):1520-9, 2011). We herein present a video (6 min) demonstrating the maneuver principles of this technique, showing it as a safe and feasible approach. A 32-year-old male, with BMI 43.4 kg/m(2), underwent LSG. On the tenth POD, he presented with a leak and initially was managed with the following approach: laparoscopic exploration, drainage, endoclips, and 20-mm balloon dilation. However, the leak remained for a period of 6 months. On the endoscopy, a septum was identified between the leak site and gastric pouch, so it was decided to "reshape" this area by septotomy. Septotomy procedure: Sequential incisions were performed using argon plasma coagulation (APC) with 2.5 flow and 50 W (WEM, SP, Brazil) over the septum in order to allow communication between the perigastric cavity (leak site) and the gastric lumen. The principles below must be followed: (1) Scope position: the endoscopist's left hand holds the control body of the gastroscope while the right hand holds the insertion tube; the APC catheter has no need to be fixed. This avoids movements and unprogrammed maneuvers. (2) Before cutting, the septum is placed in the six o'clock position on the endoscopic view, by rotating the gastroscope. (3) The septum is sectioned until the bottom of the perigastric cavity (leak site). (4) That section is made towards the staple line. (5) Just after the septotomy, a Savory-Gilliard guidewire (Cook Medical, Indiana, USA) through the scope must be inserted until the duodenum, followed by 30-mm balloon (Rigiflex®, Boston Scientific, MA, USA) insertion. The balloon catheter must be firmly held during gradual inflation (maximum 10 psi) to avoid slippage and laceration. This allows increasing the gastric lumen. (6) Septotomy by electrocautery with a needle knife (Boston Scientific, MA, USA) can be made when an intensive fibrotic septum is present; bleeding is rare in this case. In this case, the endoclip previously used was removed from the septum with forceps to avoid heat transmission. Small staples visualized in the fistula orifice were not completely removed due to technical difficulties and friable tissue. Two sessions were performed in 15 days, resulting in leak closure. The patient was submitted to radiological control 1 week after the second session, which revealed fistula healing, without gastric stenosis. The nasoduodenal feeding tube remained for 7 days, when the patient started oral diet. This patient was followed for 18 months without recurrence. Septotomy and balloon dilation were initially performed on a difficult-to-treat chronic fistula after gastric bypass and named before as stricturotomy (Campos JM, Siqueira LT, Ferraz AA, et al., J Am Coll Surg 204(4):711, 2007). This procedure allows internal drainage of the fistula and deviates oral intake to the pouch. In addition, achalasia balloon dilation treats strictures and axis deviation of the gastric chamber, promoting reduction of the intragastric pressure. Septotomy and balloon dilation are technically feasible and might be useful in selected cases for closure of chronic leaks after LSG.

Stress and Pore Pressure Measurement in IODP Riser Drilling: An Example from Expedition 319, Kumano Basin offshore SW Honshu, Japan

NASA Astrophysics Data System (ADS)

Saffer, D. M.; McNeill, L. C.; Byrne, T. B.; Araki, E.; Flemings, P. B.; Conin, M.; Eguchi, N. O.; Takahashi, K.; Toczko, S.; Boutt, D. F.; Doan, M.; Kano, Y.; Ito, T.; Lin, W.

2009-12-01

In summer 2009, Integrated Ocean Drilling Program (IODP) Expedition 319 drilled a 1600 m deep riser borehole (Site C0009) in the Kumano Basin offshore SW Japan, to investigate the properties, structure and state of stress in the hanging wall above the subduction plate boundary. The first riser-based scientific drilling in IODP history allowed us to make several new scientific measurements including in situ stress magnitude, pore pressure and permeability using the Modular Formation Dynamics Tester (MDT) wireline tool, and measurement of minimum stress magnitude from Leak-off Tests (LOT). In addition, continuous monitoring of mud weight, mud gas, annular pressure, and mud losses provided data to constrain formation pore fluid pressure and stress. At Site C0009, we conducted 2 LOTs below a casing shoe at 708.6 m depth and 11 successful MDT measurements, including 9 single probe tests to measure pore pressure and fluid mobility and 2 dual packer tests: 1 to measure permeability by a drawdown test, and 1 to measure in situ stress. Measured pore pressures are approximately hydrostatic to 1463.7 m depth. We observed only minor gas shows when drilling ahead (as in-place methane was liberated from the rock at the bit) but little or no gas during pipe connections. This indicates that the borehole mud pressure exceeded the formation pore pressure, and is consistent with the MDT measurements. Permeabilities range from ~10-16 m2 - 10-14 m2, and the observed variation is consistent with lithologic changes defined in gamma ray logs. The MDT measurement at 874.3 mbsf and the LOT at 708.6 m yield values for the least principal stress of 34.8 MPa and 30.2 MPa, respectively. Both are less than the vertical stress (Sv) computed from density logs. Partial mud circulation losses occurred when the borehole mud pressure exceeded the leak-off stress measured at the base of the casing shoe; this provides an additional indirect constraint on Shmin magnitude. Mud pressure slightly in excess of the leak-off stress may have also generated poorly-developed drilling-induced tensile fractures (DITF) observed in resistivity image logs between ~750 - 1000 m. From the presence of DITF, Shmin measurements, and assuming a rock tensile strength of 1 MPa, we determine that SHmax is 35.1 MPa for the MDT stress measurement, and 30.2 MPa for the LOT. Using the MDT measurement of Shmin, the resulting principal stress magnitudes define a strike-slip faulting regime with effective stresses of Shmax’ = 14 MPa, Sv' = 7.3 MPa, and Shmin’ = 6.4 MPa. In contrast, using the LOT measurement of Shmin, the stress magnitudes indicate a normal faulting regime in which Sv’ = 6.2 MPa, Shmax’ = 2.8 MPa, and Shmin’ = 2.6 MPa.

Additional diagnostic value of multiplane echocardiography over biplane imaging in assessment of mitral prosthetic valves.

PubMed Central

Faletra, F.; De Chiara, F.; Corno, R.; Passini, L.

1996-01-01

OBJECTIVE: To evaluate how often multiplane transoesophageal echocardiography yields new or complementary data in mitral prostheses in comparison with the exclusive use of biplane imaging. PATIENTS: 73 consecutive patients with mitral prostheses who underwent multiplane transoesophageal echocardiograpy between January 1993 and December 1994. METHODS: Biplane images (transverse and longitudinal planes) and multiplane images (transverse, longitudinal, and intermediate planes) were recorded on two separate videotapes. The data provided by multiplane transoesophageal echocardiography were evaluated as (a) new data (abnormalities missed by biplane imaging); (b) complementary data (better delineating lesions already visualised by biplane imaging); or (c) redundant data (data already provided by biplane imaging). RESULTS: Multiplane transoesophageal echocardiography revealed new abnormalities in seven patients (9.5%) (thrombi in three and paraprosthetic leaks in the remaining four) and complementary data in nine (12.3%). In patients with paraprosthetic regurgitation, the possibility of continuously visualising the sewing ring by means of sequential angulations allowed the circumferential extension of the leak to be measured. In seven patients with paravalvar regurgitation who underwent surgery, the extension of the leak as measured by the multiplane approach closely corresponded with the surgical data. CONCLUSIONS: In comparison with the exclusive use of biplane imaging, the multiplane approach added new or complementary data in a significant proportion of patients with mitral prostheses. The ability to obtain the sequential adjacent planes allowed a more reliable appraisal of the extension of the leak and other abnormalities. Images PMID:8697166

Energy metabolic state in hypothermically stored boar spermatozoa using a revised protocol for efficient ATP extraction.

PubMed

Nguyen, Quynh Thu; Wallner, Ulrike; Schmicke, Marion; Waberski, Dagmar; Henning, Heiko

2016-11-15

Mammalian spermatozoa utilize ATP as the energy source for key functions on the route to fertilization. ATP and its precursor nucleotides ADP and AMP are regularly investigated in sperm physiology studies, mostly by bioluminescence assays. Assay results vary widely, mainly due to different efficiencies in nucleotide extraction and prevention of their enzymatic degradation. Here, we describe a revised, validated protocol for efficient phosphatase inhibition and adenine nucleotide extraction resulting in consistently high ATP concentrations exceeding previously reported values for boar spermatozoa up to 20-fold. The revised assay is applicable for determining ATP concentrations and adenylate energy charge in extracts from fresh and frozen samples, thereby allowing simultaneous assessment of semen samples from long-term storage experiments. After validation, the assay was applied to liquid-preserved boar spermatozoa stored at 17°C and 5°C for 24 and 72 h. Cooling to 5°C, but not storage duration, reduced ATP concentration in spermatozoa (P<0.05), which was accompanied by the appearance of AMP and ADP in the preservation medium. ATP and energy charge were highly correlated to the proportion of membrane-intact spermatozoa, supporting the idea of nucleotides leaking through disrupted membranes in cold-shocked cells. The present assay allows highly standardized studies of energy metabolism in spermatozoa. © 2016. Published by The Company of Biologists Ltd.

Energy metabolic state in hypothermically stored boar spermatozoa using a revised protocol for efficient ATP extraction

PubMed Central

Nguyen, Quynh Thu; Wallner, Ulrike; Schmicke, Marion; Waberski, Dagmar

2016-01-01

ABSTRACT Mammalian spermatozoa utilize ATP as the energy source for key functions on the route to fertilization. ATP and its precursor nucleotides ADP and AMP are regularly investigated in sperm physiology studies, mostly by bioluminescence assays. Assay results vary widely, mainly due to different efficiencies in nucleotide extraction and prevention of their enzymatic degradation. Here, we describe a revised, validated protocol for efficient phosphatase inhibition and adenine nucleotide extraction resulting in consistently high ATP concentrations exceeding previously reported values for boar spermatozoa up to 20-fold. The revised assay is applicable for determining ATP concentrations and adenylate energy charge in extracts from fresh and frozen samples, thereby allowing simultaneous assessment of semen samples from long-term storage experiments. After validation, the assay was applied to liquid-preserved boar spermatozoa stored at 17°C and 5°C for 24 and 72 h. Cooling to 5°C, but not storage duration, reduced ATP concentration in spermatozoa (P<0.05), which was accompanied by the appearance of AMP and ADP in the preservation medium. ATP and energy charge were highly correlated to the proportion of membrane-intact spermatozoa, supporting the idea of nucleotides leaking through disrupted membranes in cold-shocked cells. The present assay allows highly standardized studies of energy metabolism in spermatozoa. PMID:27612509

Mobile Measurement of Methane and Ethane for the Detection and Attribution of Natural Gas Pipeline Leaks Using Off-Axis Integrated Output Spectroscopy

NASA Astrophysics Data System (ADS)

Leen, J. B.; Spillane, S.; Gardner, A.; Hansen, P. C.; Gupta, M.; Baer, D. S.

2015-12-01

Natural gas leaks pose a risk to public safety both because of potential explosions as well as from the greenhouse gas potential of fugitive methane. The rapid and cost effective detection of leaks in natural gas distribution is critical to providing a system that is safe for the public and the environment. Detection of methane from a mobile platform (vehicles, aircraft, etc.) is an accepted method of identifying leaks. A robust approach to differentiating pipeline gas (thermogenic) from other biogenic sources is the detection of ethane along with methane. Ethane is present in nearly all thermogenic gas but not in biogenic sources and its presence can be used to positively identify a gas sample. We present a mobile system for the simultaneous measurement of methane and ethane that is capable of detecting pipeline leaks and differentiating pipeline gas from other biogenic sources such as landfills, swamps, sewers, and enteric fermentation. The mobile system consists of a high precision GPS, sonic anemometer, and methane/ethane analyzer based on off-axis integrated cavity output spectroscopy (OA-ICOS). In order to minimize the system cost and facilitate the wide use of mobile leak detection, the analyzer operates in the near-infrared portion of the spectrum where lasers and optics are significantly less costly than in the mid-infrared. The analyzer is capable of detecting methane with a precision of <2 ppb (1σ in 1 sec) and detecting ethane with a precision of <30 ppb (1σ in 1 sec). Additionally, measurement rates of 5 Hz allow for detection of leaks at speeds up to 50 mph. The sonic anemometer, GPS and analyzer inlet are mounted to a generic roof rack for attachment to available fleet vehicles. The system can detect leaks having a downwind concentration of as little as 10 ppb of methane above ambient, while leaks 500 ppb above ambient can be identified as thermogenic with greater than 99% certainty (for gas with 6% ethane). Finally, analysis of wind data provides an estimate of leak direction and distance. The system presented provides a robust, cost effective solution to natural gas leak detection and attribution to maximize safety and minimize greenhouse gas impacts of distribution systems.

In situ formation of leak-free polyethylene glycol (PEG) membranes in microfluidic fuel cells.

PubMed

Ho, W F; Lim, K M; Yang, K-L

2016-11-29

Membraneless microfluidic fuel cells operated under two co-laminar flows often face serious fuel cross-over problems, especially when flow rates are close to zero. In this study, we show that polyethylene glycol (PEG) monomers can be cross-linked inside microfluidic channels to form leak-free PEG membranes, which prevent mixing of two incompatible electrolyte solutions while allowing diffusion of certain molecules (e.g. glucose) and ions. By using PEG monomers of different molecular weights and cross-linking conditions, we are able to tailor selectivity of the membrane to allow passage of glucose while blocking larger molecules such as trypan blue. As a proof of principle, a microfluidic fuel cell with a PEG membrane and two incompatible electrolytes (acid and base) is demonstrated. Thanks to the leak-free nature of the PEG membrane, these two electrolytes do not mix together even at very slow flow rates. This microfluidic fuel cell is able to generate a voltage up to ∼450 mV from 10 mM of glucose with a flow rate of 20 μL min -1 . This microfluidic fuel cell is potentially useful as a miniature power source for many applications.

Heart valve surgery

MedlinePlus

... with an artificial valve (this is called the Ross Procedure). This procedure may be useful for people ... valve that does not close all the way will allow blood to leak backwards. This is called ...

Repairing pipes on the fly

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1997-04-01

When piping develops leaks, the natural instinct is to shut the process down, purge the lines and call in maintenance crews to make the repairs. There is, however, an alternative: on-the-fly repairs. Through the use of specialized tools, equipment and technicians, shut-off valves can be installed and leaks repaired without interrupting production. The split sleeve offers one of the simpler approaches to on-the-fly repairs. Two half cylinders with inside diameter slightly larger than the outside diameter slightly larger than the outside diameter of the pipe to be repaired are slipped over the latter some distance form the leak and looselymore » bolted together. The cylinder is then slid over the leaking area and the bolts tightened. Gaskets inside the half cylinders provide the needed seal between the pipe and the cylinder. Installing a shut-off valve in an operating pipeline requires much more specialized equipment and skills than does repairing a leak with a split sleeve. A device available from International Piping Services Co. allows a trained crew to isolate a section of pipe, drill out the isolated portion, install a blocking valve and then remove the isolation system--all while continuing to operate the pipeline at temperatures to 700 F and pressures to 700 psi. But Herb Porter, CEO of Ipsco, cautions that unlike the repairing leaks with a split sleeve, installing a blocking valve on-the-fly always demands the services of a highly trained crew.« less

Definition and classification of chyle leak after pancreatic operation: A consensus statement by the International Study Group on Pancreatic Surgery.

PubMed

Besselink, Marc G; van Rijssen, L Bengt; Bassi, Claudio; Dervenis, Christos; Montorsi, Marco; Adham, Mustapha; Asbun, Horacio J; Bockhorn, Maximillian; Strobel, Oliver; Büchler, Markus W; Busch, Olivier R; Charnley, Richard M; Conlon, Kevin C; Fernández-Cruz, Laureano; Fingerhut, Abe; Friess, Helmut; Izbicki, Jakob R; Lillemoe, Keith D; Neoptolemos, John P; Sarr, Michael G; Shrikhande, Shailesh V; Sitarz, Robert; Vollmer, Charles M; Yeo, Charles J; Hartwig, Werner; Wolfgang, Christopher L; Gouma, Dirk J

2017-02-01

Recent literature suggests that chyle leak may complicate up to 10% of pancreatic resections. Treatment depends on its severity, which may include chylous ascites. No international consensus definition or grading system of chyle leak currently is available. The International Study Group on Pancreatic Surgery, an international panel of pancreatic surgeons working in well-known, high-volume centers, reviewed the literature and worked together to establish a consensus on the definition and classification of chyle leak after pancreatic operation. Chyle leak was defined as output of milky-colored fluid from a drain, drain site, or wound on or after postoperative day 3, with a triglyceride content ≥110 mg/dL (≥1.2 mmol/L). Three different grades of severity were defined according to the management needed: grade A, no specific intervention other than oral dietary restrictions; grade B, prolongation of hospital stay, nasoenteral nutrition with dietary restriction, total parenteral nutrition, octreotide, maintenance of surgical drains, or placement of new percutaneous drains; and grade C, need for other more invasive in-hospital treatment, intensive care unit admission, or mortality. This classification and grading system for chyle leak after pancreatic resection allows for comparison of outcomes between series. As with the other the International Study Group on Pancreatic Surgery consensus statements, this classification should facilitate communication and evaluation of different approaches to the prevention and treatment of this complication. Copyright © 2016 Elsevier Inc. All rights reserved.

KSC-02pd1709

NASA Image and Video Library

2002-11-12

KENNEDY SPACE CENTER, FLA. -- In the Payload Changeout Room, Launch Pad 39A, workers raise a platform toward the forward cargo bay area of Space Shuttle Endeavour to search for an oxygen leak. The launch of Endeavour on mission STS-113 was postponed Nov. 10, following the completion of tanking operations, due to higher than allowable oxygen levels in the orbiter's midbody. Workers will investigate the exact location and possible cause of the leak, and effect repairs. Launch has been tentatively set for no earlier than Nov. 18, between 7 and 11 p.m. EST.

KSC-02pd1712

NASA Image and Video Library

2002-11-12

KENNEDY SPACE CENTER, FLA. -- Workers in the Payload Changeout Room, Launch Pad 39A, are on a platform in the forward cargo bay area of Space Shuttle Endeavour to search for an oxygen leak. The launch of Endeavour on mission STS-113 was postponed Nov. 10, following the completion of tanking operations, due to higher than allowable oxygen levels in the orbiter's midbody. Workers will investigate the exact location and possible cause of the leak, and effect repairs. Launch has been tentatively set for no earlier than Nov. 18, between 7 and 11 p.m. EST.

KSC-02pd1710

NASA Image and Video Library

2002-11-12

KENNEDY SPACE CENTER, FLA. -- Workers in the Payload Changeout Room, Launch Pad 39A, ride a platform toward the forward cargo bay area of Space Shuttle Endeavour to search for an oxygen leak. The launch of Endeavour on mission STS-113 was postponed Nov. 10, following the completion of tanking operations, due to higher than allowable oxygen levels in the orbiter's midbody. Workers will investigate the exact location and possible cause of the leak, and effect repairs. Launch has been tentatively set for no earlier than Nov. 18, between 7 and 11 p.m. EST.

KSC-02pd1711

NASA Image and Video Library

2002-11-12

KENNEDY SPACE CENTER, FLA. -- Workers in the Payload Changeout Room, Launch Pad 39A, are on a platform in the forward cargo bay area of Space Shuttle Endeavour to search for an oxygen leak. The launch of Endeavour on mission STS-113 was postponed Nov. 10, following the completion of tanking operations, due to higher than allowable oxygen levels in the orbiter's midbody. Workers will investigate the exact location and possible cause of the leak, and effect repairs. Launch has been tentatively set for no earlier than Nov. 18, between 7 and 11 p.m. EST.

Negative-pressure and low-pressure hydrocephalus: the role of cerebrospinal fluid leaks resulting from surgical approaches to the cranial base.

PubMed

Filippidis, Aristotelis S; Kalani, M Yashar S; Nakaji, Peter; Rekate, Harold L

2011-11-01

Negative-pressure and low-pressure hydrocephalus are rare clinical entities that are frequently misdiagnosed. They are characterized by recurrent episodes of shunt failure because the intracranial pressure is lower than the opening pressure of the valve. In this report the authors discuss iatrogenic CSF leaks as a cause of low- or negative-pressure hydrocephalus after approaches to the cranial base. The authors retrospectively reviewed cases of low-pressure or negative-pressure hydrocephalus presenting after cranial approaches complicated with a CSF leak at their institution. Three patients were identified. Symptoms of high intracranial pressure and ventriculomegaly were present, although the measured pressures were low or negative. A blocked communication between the ventricles and the subarachnoid space was documented in 2 of the cases and presumed in the third. Shunt revisions failed repeatedly. In all cases, temporary clinical and radiographic improvement resulted from external ventricular drainage at subatmospheric pressures. The CSF leaks were sealed and CSF communication was reestablished operatively. In 1 case, neck wrapping was used with temporary success. Negative-pressure or low-pressure hydrocephalus associated with CSF leaks, especially after cranial base approaches, is difficult to treat. The solution often requires the utilization of subatmospheric external ventricular drains to establish a lower ventricular drainage pressure than the drainage pressure created in the subarachnoid space, where the pressure is artificially lowered by the CSF leak. Treatment involves correction of the CSF leak, neck wrapping to increase brain turgor and allow the pressure in the ventricles to rise to the level of the opening pressure of the valve, and reestablishing the CSF route.

The Soil Microbial Response to a Massive Natural Gas Leak

NASA Astrophysics Data System (ADS)

Tavormina, P. L.; Newman, S.; Shen, L.; Connon, S. A.; Okumura, M.; Orphan, V. J.

2016-12-01

The 2015/2016 gas leak in the Porter Ranch community (Southern California) was the largest natural gas leak in US history. While considerable attention has focused on the amount of methane released to the atmosphere and the effects of other gas components on human well-being, less attention has been given to the response of soil microbes to this event. These microbes represent natural pathways for utilization of C1 compounds in soils and, possibly, untapped potential to remediate natural and anthropogenic gas emissions. We monitored onsite and background soil methane concentrations and microbial communities during and following the Porter Ranch gas leak. Soil core samples (25cm depth, collected twice monthly beginning in January 2016) were preserved for DNA, RNA, microscopic, stable isotope probing, and chromatographic methods. Simultaneously to coring, gas from soil pore spaces was collected for cavity ringdown spectroscopy to measure carbon dioxide, methane and ethane concentrations, and estimate corresponding isotopic values in carbon dioxide and methane. By pairing these measurements with high throughput sequencing, transcript analysis, and cultivation, we demonstrate discrete shifts in the total microbial community in surface (0 - 5 cm) and deep (20 - 25 cm) soils. Importantly, we find that methane consumption likely occurred in surface soils during and following the leak. The lineages most significantly correlated with elevated methane from the leak event were five orders of magnitude more abundant near the leak event in space and time, indicating a microbial bloom. These lineages are previously unrecognized members of Sphingomonadaceae, and they encode at least two biochemical pathways for methane oxidation. Cultivation of the first representative of this group now allows more detailed investigation into its capacity for microbially-mediated soil methane oxidation and mitigation.

A hybrid thermal video and FTIR spectrometer system for rapidly locating and characterizing gas leaks

NASA Astrophysics Data System (ADS)

Williams, David J.; Wadsworth, Winthrop; Salvaggio, Carl; Messinger, David W.

2006-08-01

Undiscovered gas leaks, known as fugitive emissions, in chemical plants and refinery operations can impact regional air quality and present a loss of product for industry. Surveying a facility for potential gas leaks can be a daunting task. Industrial leak detection and repair programs can be expensive to administer. An efficient, accurate and cost effective method for detecting and quantifying gas leaks would both save industries money by identifying production losses and improve regional air quality. Specialized thermal video systems have proven effective in rapidly locating gas leaks. These systems, however, do not have the spectral resolution for compound identification. Passive FTIR spectrometers can be used for gas compound identification, but using these systems for facility surveys is problematic due to their small field of view. A hybrid approach has been developed that utilizes the thermal video system to locate gas plumes using real time visualization of the leaks, coupled with the high spectral resolution FTIR spectrometer for compound identification and quantification. The prototype hybrid video/spectrometer system uses a sterling cooled thermal camera, operating in the MWIR (3-5 μm) with an additional notch filter set at around 3.4 μm, which allows for the visualization of gas compounds that absorb in this narrow spectral range, such as alkane hydrocarbons. This camera is positioned alongside of a portable, high speed passive FTIR spectrometer, which has a spectral range of 2 - 25 μm and operates at 4 cm -1 resolution. This system uses a 10 cm telescope foreoptic with an onboard blackbody for calibration. The two units are optically aligned using a turning mirror on the spectrometer's telescope with the video camera's output.

Hydrophobic, Porous Battery Boxes

NASA Technical Reports Server (NTRS)

Bragg, Bobby J.; Casey, John E., Jr.

1995-01-01

Boxes made of porous, hydrophobic polymers developed to contain aqueous potassium hydroxide electrolyte solutions of zinc/air batteries while allowing air to diffuse in as needed for operation. Used on other types of batteries for in-cabin use in which electrolytes aqueous and from which gases generated during operation must be vented without allowing electrolytes to leak out.

Hazardous fluid leak detector

DOEpatents

Gray, Harold E.; McLaurin, Felder M.; Ortiz, Monico; Huth, William A.

1996-01-01

A device or system for monitoring for the presence of leaks from a hazardous fluid is disclosed which uses two electrodes immersed in deionized water. A gas is passed through an enclosed space in which a hazardous fluid is contained. Any fumes, vapors, etc. escaping from the containment of the hazardous fluid in the enclosed space are entrained in the gas passing through the enclosed space and transported to a closed vessel containing deionized water and two electrodes partially immersed in the deionized water. The electrodes are connected in series with a power source and a signal, whereby when a sufficient number of ions enter the water from the gas being bubbled through it (indicative of a leak), the water will begin to conduct, thereby allowing current to flow through the water from one electrode to the other electrode to complete the circuit and activate the signal.

Experimental testing of a foam/multilayer insulation (FMLI) thermal control system (TCS) for use on a cryogenic upper stage

NASA Astrophysics Data System (ADS)

Hastings, Leon J.; Martin, James J.

1998-01-01

An 18-m3 system-level test bed termed the Multipurpose Hydrogen Test Bed (MHTB has been used to evaluate a foam/multilayer combination insulation concept. The foam element (Isofoam SS-1171) protects against ground hold/ascent flight environments, and allows the use of dry nitrogen purge as opposed to a more complex/heavy helium purge subsystem. The MLI (45 layers of Double Aluminized Mylar with Dacron spacers) is designed for an on-orbit storage period of 45 days. Unique MLI features included; a variable layer density (reduces weight and radiation losses), larger but fewer DAM vent perforations (reduces radiation losses), and a roll wrap installation which resulted in a very robust MLI and reduced both assembly man-hours and seam heat leak. Ground hold testing resulted in an average heat leak of 63 W/m2 and purge gas liquefaction was successfully prevented. The orbit hold simulation produced a heat leak of 0.22 W/m2 with 305 K boundary which, compared to historical data, represents a 50-percent heat leak reduction.

Schlieren optics for leak detection

NASA Technical Reports Server (NTRS)

Peale, Robert E.; Ruffin, Alranzo B.

1995-01-01

The purpose of this research was to develop an optical method of leak detection. Various modifications of schlieren optics were explored with initial emphasis on leak detection of the plumbing within the orbital maneuvering system of the space shuttle (OMS pod). The schlieren scheme envisioned for OMS pod leak detection was that of a high contrast pattern on flexible reflecting material imaged onto a negative of the same pattern. We find that the OMS pod geometry constrains the characteristic length scale of the pattern to the order of 0.001 inch. Our experiments suggest that optical modulation transfer efficiency will be very low for such patterns, which will limit the sensitivity of the technique. Optical elements which allow a negative of the scene to be reversibly recorded using light from the scene itself were explored for their potential in adaptive single-ended schlieren systems. Elements studied include photochromic glass, bacteriorhodopsin, and a transmissive liquid crystal display. The dynamics of writing and reading patterns were studied using intensity profiles from recorded images. Schlieren detection of index gradients in air was demonstrated.

β-Adrenergic induced SR Ca2+ leak is mediated by an Epac-NOS pathway.

PubMed

Pereira, Laëtitia; Bare, Dan J; Galice, Samuel; Shannon, Thomas R; Bers, Donald M

2017-07-01

Cardiac β-adrenergic receptors (β-AR) and Ca 2+ -Calmodulin dependent protein kinase (CaMKII) regulate both physiological and pathophysiological Ca 2+ signaling. Elevated diastolic Ca 2+ leak from the sarcoplasmic reticulum (SR) contributes to contractile dysfunction in heart failure and to arrhythmogenesis. β-AR activation is known to increase SR Ca 2+ leak via CaMKII-dependent phosphorylation of the ryanodine receptor. Two independent and reportedly parallel pathways have been implicated in this β-AR-CaMKII cascade, one involving exchange protein directly activated by cAMP (Epac2) and another involving nitric oxide synthase 1 (NOS1). Here we tested whether Epac and NOS function in a single series pathway to increase β-AR induced and CaMKII-dependent SR Ca 2+ leak. Leak was measured as both Ca 2+ spark frequency and tetracaine-induced shifts in SR Ca 2+ , in mouse and rabbit ventricular myocytes. Direct Epac activation by 8-CPT (8-(4-chlorophenylthio)-2'-O-methyl-cAMP) mimicked β-AR-induced SR Ca 2+ leak, and both were blocked by NOS inhibition. The same was true for myocyte CaMKII activation (assessed via a FRET-based reporter) and ryanodine receptor phosphorylation. Inhibitor and phosphorylation studies also implicated phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt) downstream of Epac and above NOS activation in this pathway. We conclude that these two independently characterized parallel pathways function mainly via a single series arrangement (β-AR-cAMP-Epac-PI3K-Akt-NOS1-CaMKII) to mediate increased SR Ca 2+ leak. Thus, for β-AR activation the cAMP-PKA branch effects inotropy and lusitropy (by effects on Ca 2+ current and SR Ca 2+ -ATPase), this cAMP-Epac-NOS pathway increases pathological diastolic SR Ca 2+ leak. This pathway distinction may allow novel SR Ca 2+ leak therapeutic targeting in treatment of arrhythmias in heart failure that spare the inotropic and lusitropic effects of the PKA branch. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel laparoscopic narrow band imaging for real-time detection of bile leak during hepatectomy: proof of the concept in a porcine model.

PubMed

Diana, Michele; Usmaan, Hameed; Legnèr, Andras; Yu-Yin, Liu; D'Urso, Antonio; Halvax, Peter; Nagao, Yoshihiro; Pessaux, Patrick; Marescaux, Jacques

2016-07-01

Bile leakage is a serious complication occurring in up to 10 % of hepatic resections. Intraoperative detection of bile leakage is challenging, and concomitant blood oozing can mask the presence of bile. Intraductal dye injection [methylene blue or indocyanine green (ICG)] is a validated technique to detect bile leakage. However, this method is time-consuming, particularly in the laparoscopic setting. A novel narrow band imaging (NBI) modality (SPECTRA-A; Karl Storz, Tuttlingen, Germany) allows easy discrimination of the presence of bile, which appears in clear orange, by image processing. The aim of this experimental study was to evaluate SPECTRA-A ability to detect bile leakage. Twelve laparoscopic partial hepatectomies were performed in seven pigs. The common bile duct was clipped distally and dissected, and a catheter was inserted and secured with a suture or a clip. Liver dissection was achieved with an ultrasonic cutting device. Dissection surfaces were checked by frequently switching on the SPECTRA filter to identify the presence of bile leakage. Intraductal ICG injection through the catheter was performed to confirm SPECTRA findings. Three active bile leakages were obtained out of 12 hepatectomies and successfully detected intraoperatively by the SPECTRA. There was complete concordance between NBI and ICG fluorescence detection. No active leaks were found in the remaining cases with both techniques. The leaking area identified was sutured, and SPECTRA was used to assess the success of the repair. The SPECTRA laparoscopic image processing system allows for rapid detection of bile leaks following hepatectomy without any contrast injection.

Time to CUSUM: simplified reporting of outcomes in colorectal surgery.

PubMed

Bowles, Thomas A; Watters, David A

2007-07-01

Surgical audit has added value when outcomes can be compared and individual surgeons receive feedback. It is expected that surgeons compare their results with others in similar local practice, the published work, or peers from a craft group audit. Although feedback and comparison are worthy aims, for many surgeons the standards have not been agreed nor is there a craft group audit. The aim of this paper was to develop a reporting format for surgeons carrying out colorectal surgery in a regional hospital. The performance of 13 individual surgeons was analysed using a comprehensive colorectal audit with more than 600 cases. Feedback included caseload and type. Risk stratification of outcomes included; operation urgency, age and Physiological and Operative Severity Score for enUmeration of Mortality and Morbidity. Outcome measures were anastomotic leaks, end stoma rates, unplanned reoperations and mortality. Visual feedback included cumulative summation graphs for elective leaks, mortality and unplanned reoperations. A single A4 page of an individuals performance could be prepared that allowed comparison to the groups data overall. Alerts were set at 2-5% elective leaks, 4-7.5% mortality and 4-11% unplanned return to theatre. Cumulative summation graphs added to this allowed a visual guide to the key performance indicators. Surgeons need to determine how they will review their individual and collective results. These are equally important to the reported work. Detailed analysis of risk-stratified data should occur. Binary outcomes such as leak, mortality and unplanned reoperations may be followed by cumulative summation graphs. This provides a continually updated method of feedback, enabling immediate visual feedback of a surgeon's performance.

Evaluation program for secondary spacecraft cells: Acceptance test of Eagle-Picher 100 ampere-hour nickel-cadmium cells with auxiliary electrodes

NASA Technical Reports Server (NTRS)

Christy, D. E.

1972-01-01

Tests were conducted on a group of 29 cells for the purpose of removing from the life cycle program all cells found to have electrolyte leakage, internal shorts, low capacity, or inability to recover open circuit voltage above 1.150 volts after the cell short test. The test findings include the following: (1) All the cells exceeded the rated capacity of 103.5 to 119.0 ampere-hours on all three capacity checks. (2) All cells recovered above the 1.150 volt requirement after the cell short test. (3) The cells cannot be overcharged at the c/10 rate without exceeding 1.500 volts after approximately 12 to 13 hours of charge. (4) The resistance value necessary to provide maximum signal power across the auxiliary electrode was found to be 10 ohms. (5) One cell revealed a definite leak at the negative terminal.

Detecting subsurface fluid leaks in real-time using injection and production rates

NASA Astrophysics Data System (ADS)

Singh, Harpreet; Huerta, Nicolas J.

2017-12-01

CO2 injection into geologic formations for either enhanced oil recovery or carbon storage introduces a risk for undesired fluid leakage into overlying groundwater or to the surface. Despite decades of subsurface CO2 production and injection, the technologies and methods for detecting CO2 leaks are still costly and prone to large uncertainties. This is especially true for pressure-based monitoring methods, which require the use of simplified geological and reservoir flow models to simulate the pressure behavior as well as background noise affecting pressure measurements. In this study, we propose a method to detect the time and volume of fluid leakage based on real-time measurements of well injection and production rates. The approach utilizes analogies between fluid flow and capacitance-resistance modeling. Unlike other leak detection methods (e.g. pressure-based), the proposed method does not require geological and reservoir flow models to simulate the behavior that often carry significant sources of uncertainty; therefore, with our approach the leak can be detected with greater certainty. The method can be applied to detect when a leak begins by tracking a departure in fluid production rate from the expected pattern. The method has been tuned to detect the effect of boundary conditions and fluid compressibility on leakage. To highlight the utility of this approach we use our method to detect leaks for two scenarios. The first scenario simulates a fluid leak from the storage formation into an above-zone monitoring interval. The second scenario simulates intra-reservoir migration between two compartments. We illustrate this method to detect fluid leakage in three different reservoirs with varying levels of geological and structural complexity. The proposed leakage detection method has three novelties: i) requires only readily-available data (injection and production rates), ii) accounts for fluid compressibility and boundary effects, and iii) in addition to detecting the time when a leak is activated and the volume of that leakage, this method provides an insight about the leak location, and reservoir connectivity. We are proposing this as a complementary method that can be used with other, more expensive, methods early on in the injection process. This will allow an operator to conduct more expensive surveys less often because the proposed method can show if there are no leaks on a monthly basis that is cheap and fast.

Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

NASA Technical Reports Server (NTRS)

DeSimpelaere, Edward

2011-01-01

The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a cabin leak occurring. The paper also offers a look at how different equipment configurations on future spacecraft impact the previously defined cabin leak operational philosophy and includes additional operational methods and considerations that result due to various configurations. The intent is to showcase these various considerations and highlight the variability they allow. The paper concludes with a selection of the author s personal observations from a spacecraft operator's point of view and recommendations with the goal of improving the design and operations of future spacecraft.

Field Observations of Methane Emissions from Unconventional and Conventional Fossil Fuel Exploration

NASA Astrophysics Data System (ADS)

Dubey, M.; Lindenmaier, R.; Arata, C.; Costigan, K. R.; Frankenberg, C.; Kort, E. A.; Rahn, T. A.; Henderson, B. G.; Love, S. P.; Aubrey, A. D.

2013-12-01

Energy from methane (CH4) has lower carbon dioxide and air pollutant emissions per unit energy produced than coal or oil making it a desirable fossil fuel. Hydraulic fracturing is allowing United States to harvest the nation's abundant domestic shale gas reservoirs to achieve energy independence. However, CH4 is a gas that is hard to contain during mining, processing, transport and end-use. Therefore fugitive CH4 leaks occur that are reported in bottom up inventories by the EPA. Recent targeted field observations at selected plays have provided top down CH4 leak estimates that are larger than the reported EPA inventories. Furthermore, no long-term regional baselines are available to delineate leaks from unconventional mining operations from historical conventional mining. We will report and compare observations of fugitive CH4 leaks from conventional and unconventional mining to understand changes from technology shifts. We will report in situ and regional column measurements of CH4, its isotopologue 13CH4 and ethane (C2H6) at our Four Corners site near Farmington, NM. The region has substantial coal bed methane, conventional oil and gas production, processing and distribution with minimal hydraulic fracturing activity. We observe large enhancements in in situ and regional column CH4 with distinct time dependence. Our in situ 13CH4 observations and remote C2H6/CH4 provide strong evidence of thermogenic sources. Comparisons of WRF-simulations with emissions inventory (Edgar) with our observations show that the fugitive CH4 leaks from conventional mining are 3 times greater than reported. We also compare in situ mobile surveys of fugitive CH4 and 13CH4 leak signals in basins with conventional (San Juan) mining and unconventional (Permian and Powder River) mining. A large number of active and closed wells were sampled in these regions. Furthermore, play scale surveys on public roads allowed us to gain a regional perspective. The composition of atmospheric 13CH4 observed in the Powder River basin was lighter than the Permian and San Juan basins indicating a higher microbial generated fraction. More extensive and larger CH4 enhancements were measured in the Permian basin that could be a result of the large expansion of unconventional oil and gas production in this region. However, there are variations amongst wells and plays suggesting that operator practices and reservoir formation play a role in determining the fugitive leaks.

AIRFIX: the first digital postoperative chest tube airflowmetry--a novel method to quantify air leakage after lung resection.

PubMed

Anegg, Udo; Lindenmann, Jorg; Matzi, Veronika; Mujkic, Dzenana; Maier, Alfred; Fritz, Lukas; Smolle-Jüttner, Freyja Maria

2006-06-01

Prolonged air leak after pulmonary resection is a common complication and a major limiting factor for early discharge from hospital. Currently there is little consensus on its management. The aim of this study was to develop and evaluate a measuring device which allows a simple digital bed-side quantification of air-leaks compatible to standard thoracic drainage systems. The measuring device (AIRFIX) is based upon a 'mass airflow' sensor with a specially designed software package that is connected to a thoracic suction drainage system. Its efficacy in detecting pulmonary air-leaks was evaluated in a series of 204 patients; all postoperative measurements were done under standardized conditions; the patients were asked to cough, to take a deep breath, to breathe out against the resistance of a flutter valve, to keep breath and to breathe normally. As standard parameters, the leakage per breath or cough (ml/b) as well as the leakage per minute (ml/min) were displayed and recorded on the computer. Air-leaks within a range of 0.25-45 ml/b and 5-900 ml/min were found. Removal of the chest tubes was done when leakage volume on Heimlich valve was less than 1.0 ml/b or 20 ml/min. After drain removal based upon the data from chest tube airflowmetry none of the patients needed re-drainage due to pneumothorax. The AIRFIX device for bed-side quantification of air-leaks has proved to be very simple and helpful in diagnosis and management of air-leaks after lung surgery, permitting drain removal without tentative clamping.

Reliable Intraoperative Repair Nuances of Cerebrospinal Fluid Leak in Anterior Cervical Spine Surgery and Review of the Literature.

PubMed

Mitchell, Bartley D; Verla, Terence; Reddy, Duemani; Winnegan, Lona; Omeis, Ibrahim

2016-04-01

Cerebrospinal fluid (CSF) leak during anterior cervical spine surgery can lead to complications, including wound breakdown, meningitis, headaches, need for lumbar drain, or additional surgery. These leaks can be difficult to manage given the limited field of view and lack of deep access. Herein, we describe 8 consecutive patients who underwent intraoperative repair of CSF leak, with no postoperative evidence of wound dehiscence or drainage. A retrospective review was performed on 8 cases where CSF leak was encountered during an anterior cervical spine surgery. Patients had ossification of the posterior longitudinal ligament, intradural disk herniation, or dural ectasia. Intraoperative repair was as follows. First, CSF was drained to low pressure, and durotomy was covered by dural substitute and sealant agent. Then the interbody graft used was manually undersized in the anteroposterior dimension to allow for expansion of the agents used. Anterior instrumentation was then performed. Finally, a wound drain was anchored to a biologic bag for shoulder level passive drainage. In all 8 cases, there were no cases of wound dehiscence or CSF leak using this strategy. Likewise, there was no evidence of cord compression or neurologic deficits. No meningitis or persistent headaches were reported, and there was no need for lumbar drain placement at any time postoperatively. Once durotomy is encountered during anterior spine surgery, draining the CSF to a low pressure followed by dural substitute with a sealing agent, followed by a smaller anteroposterior size graft is an effective strategy of preventing complications in an inescapable problem. Copyright © 2016 Elsevier Inc. All rights reserved.

Hydrogen Sensors Boost Hybrids; Today's Models Losing Gas?

NASA Technical Reports Server (NTRS)

2005-01-01

Advanced chemical sensors are used in aeronautic and space applications to provide safety monitoring, emission monitoring, and fire detection. In order to fully do their jobs, these sensors must be able to operate in a range of environments. NASA has developed sensor technologies addressing these needs with the intent of improving safety, optimizing combustion efficiencies, and controlling emissions. On the ground, the chemical sensors were developed by NASA engineers to detect potential hydrogen leaks during Space Shuttle launch operations. The Space Shuttle uses a combination of hydrogen and oxygen as fuel for its main engines. Liquid hydrogen is pumped to the external tank from a storage tank located several hundred feet away. Any hydrogen leak could potentially result in a hydrogen fire, which is invisible to the naked eye. It is important to detect the presence of a hydrogen fire in order to prevent a major accident. In the air, the same hydrogen-leak dangers are present. Stress and temperature changes can cause tiny cracks or holes to form in the tubes that line the Space Shuttle s main engine nozzle. Such defects could allow the hydrogen that is pumped through the nozzle during firing to escape. Responding to the challenges associated with pinpointing hydrogen leaks, NASA endeavored to improve propellant leak-detection capabilities during assembly, pre-launch operations, and flight. The objective was to reduce the operational cost of assembling and maintaining hydrogen delivery systems with automated detection systems. In particular, efforts have been focused on developing an automated hydrogen leak-detection system using multiple, networked hydrogen sensors that are operable in harsh conditions.

A Fully Redundant On-Line Mass Spectrometer System Used to Monitor Cryogenic Fuel Leaks on the Space Shuttle

NASA Technical Reports Server (NTRS)

Griffin, Timothy P.; Naylor, Guy R.; Haskell, William D.; Breznik, Greg S.; Mizell, Carolyn A.; Helms, William R.; Voska, N. (Technical Monitor)

2002-01-01

An on-line gas monitoring system was developed to replace the older systems used to monitor for cryogenic leaks on the Space Shuttles before launch. The system uses a mass spectrometer to monitor multiple locations in the process, which allows the system to monitor all gas constituents of interest in a nearly simultaneous manner. The system is fully redundant and meets all requirements for ground support equipment (GSE). This includes ruggedness to withstand launch on the Mobile Launcher Platform (MLP), ease of operation, and minimal operator intervention. The system can be fully automated so that an operator is notified when an unusual situation or fault is detected. User inputs are through personal computer using mouse and keyboard commands. The graphical user for detecting cryogenic leaks, many other gas constituents could be monitored using the Hazardous Gas Detection System (HGDS) 2000.

[External lumbar drainage with volumetric continuing infusion pump in patients with cerebrospinal fluid leak. A case series].

PubMed

Manso Melgosa, Ana Belén; García Gutiérrez, Helena; Fernández Porras, Mónica; Castrillo Manero, Ana Berta; Pérez Marijuán, Belén

To describe the incidence and complications arising in a number of cases of patients with cerebrospinal fluid leak treated by external lumbar drainage with infusion pump (IP) volumetric continuous from 2001 to 2014. Quantify cerebrospinal fluid leak closed by lumbar drainage with IP. Retrospective descriptive case series study. patients undergoing transsphenoidal pituitary surgery, Chiari surgery and laminectomy, that developed postoperative cerebrospinal fluid leak treated with continuous external lumbar drainage by IP. age, sex, type of intervention, variables related to the practice of the pump and complications. Average and medians were calculated for quantitative variables, frequencies and percentages for qualitative. Sample: 11 subjects. Incidence in running IP: disconnection, occlusion and acoustic alarm activation. Most frequently complication is headache; a case of pneumocephalus. The small number of subjects and the heterogeneity of these do not allow for comparison or establishing associations between variables. The resolution of the cerebrospinal fluid leak with continuous IP is lower in this study than others, and may be influenced by the small number of subjects. It should be noted the frequent activation of the pump alarm for no apparent cause. Protocol would be developed for preparing the IP team to reduce the acoustic alarm activation, and would make a prospective multicenter study. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Stellar-based calibration in the far infrared with application to IRAS Band 4

NASA Technical Reports Server (NTRS)

Kirby, D. J.; Rieke, G. H.; Lebofsky, L. A.

1994-01-01

Because stars emit very small portions of their outputs in the far infrared, using them as calibrators requires precise measurement and correction for filter leaks at shorter wavelengths. Therefore, it is common to base far infrared calibrations on planetary objects such as asteriods. However, asteroids are complex geological bodies whose thermal properties depend on their evolutionary histories as well as on their gross parameters such as mass and composition, making them difficult to model as calibrators. We propose a new method for measuring filter leaks that can be carried out using the end-to-end detector system and therefore allows reliable use of stellar calibrators. We illustrate this method by showing that the Infrared Astronomy Satellite (IRAS) 100 micrometers (Band 4) filters had a short wavelength leak of 14.3% +/- 3.6% on stars similar to alpha Boo, but that there is no detectable leak in the 60 micrometers (Band 3) filters. We derive a calibration for Band 4 from stellar colors in a way that is closely analogous to the calibrations of Bands 1, 2, and 3. With correction for the leak, the stellar-based calibration is virtually identical to the original calibration based on asteroids; this result requires that the spectra of the asteriods for the original calibration differ from greybody behavior between 60 and 100 micrometers by about 10%.

Geomechanical analysis to predict the oil leak at the wellbores in Big Hill Strategic Petroleum Reserve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Byoung Yoon

2014-02-01

Oil leaks were found in wellbores of Caverns 105 and 109 at the Big Hill Strategic Petroleum Reserve site. According to the field observations, two instances of casing damage occurred at the depth of the interbed between the caprock bottom and salt top. A three dimensional finite element model, which contains wellbore element blocks and allows each cavern to be configured individually, is constructed to investigate the wellbore damage mechanism. The model also contains element blocks to represent interface between each lithology and a shear zone to examine the interbed behavior in a realistic manner. The causes of the damagedmore » casing segments are a result of vertical and horizontal movements of the interbed between the caprock and salt dome. The salt top subsides because the volume of caverns below the salt top decrease with time due to salt creep closure, while the caprock subsides at a slower rate because the caprock is thick and stiffer. This discrepancy yields a deformation of the well. The deformed wellbore may fail at some time. An oil leak occurs when the wellbore fails. A possible oil leak date of each well is determined using the equivalent plastic strain failure criterion. A well grading system for a remediation plan is developed based on the predicted leak dates of each wellbore.« less

Geomechanical Simulation to Predict the Oil Leak at the Wellbores in Big Hill Strategic Petroleum Reserve.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Byoung; Herrick, Courtney G.

2015-02-01

Oil leaks were found in wellbores of Caverns 105 and 109 at the Big Hill Strategic Petroleum Reserve site. According to the field observations, two instances of casing damage occurred at the depth of the interbed between the caprock bottom and salt top. A three dimensional finite element model, which contains wellbore element blocks and allows each cavern to be configured individually, is constructed to investigate the wellbore damage mechanism. The model also contains element blocks to represent interface between each lithology and a shear zone to examine the interbed behavior in a realistic manner. The causes of the damagedmore » casing segments are a result of vertical and horizontal movements of the interbed between the caprock and salt dome. The salt top subsides because the volume of caverns below the salt top decrease with time due to salt creep closure, while the caprock subsides at a slower rate because the caprock is thick and stiffer. This discrepancy produces a deformation of the well. The deformed wellbore may fail at some time. An oil leak occurs when the wellbore fails. A possible oil leak date of each well is determined using an equivalent plastic strain failure criterion. A well grading system for a remediation plan is developed based on the predicted leak dates of each wellbore.« less

Cerebrospinal fluid leak (image)

MedlinePlus

... brain and spinal cord by acting like a liquid cushion. The fluid allows the organs to be buoyant protecting them from blows or other trauma. Inside the skull the cerebrospinal fluid is contained by the dura which covers ...

Spleen and Lymphatic System (For Parents)

MedlinePlus

... they have many tiny openings that allow gases, water, and nutrients to pass through to the surrounding cells, nourishing them and taking away waste products. When lymph fluid leaks through in this way it is called interstitial ...

Development of a Novel Leak-Free Constant-Pressure Cylinder for Certified Reference Materials of Liquid Hydrocarbon Mixtures.

PubMed

Kim, Yong Doo; Kang, Ji Hwan; Bae, Hyun Kil; Kang, Namgoo; Oh, Sang Hyub; Lee, Jin-Hong; Woo, Jin Chun; Lee, Sangil

2017-11-21

Liquid hydrocarbon mixtures such as liquefied petroleum gas and liquefied natural gas are becoming integral parts of the world's energy system. Certified reference materials (CRMs) of liquid hydrocarbon mixtures are necessary to allow assessment of the accuracy and traceability of the compositions of such materials. A piston-type constant-pressure cylinder (PCPC) comprising chambers for a pressurizing gas (helium) and liquid (hydrocarbons) separated by a piston can be used to develop accurate and traceable liquid hydrocarbon mixture CRMs. The development of accurate CRMs relies on the maintenance of their composition. However, a PCPC might allow hydrocarbons to leak owing to the imperfect seal of the piston. In this study, a novel leak-free bellows-type constant-pressure cylinder (BCPC) is designed and evaluated by comparison with PCPCs. Liquid hydrocarbon mixtures consisting of ethane, propane, propene, isobutane, n-butane, 1-butene, and isopentane were prepared in both types of constant pressure cylinders and then monitored to check leakages between the gas and liquid chambers. Overall, notable leakage occurred from and into both chambers in the PCPCs, whereas no leakage occurred in the BCPCs in the three months after their gravimetric preparation. The BCPCs maintained no leakage even 10 months after their preparation, whereas the PCPCs showed significantly increasing leakage during the same period.

Multi-scale modeling of CO2 dispersion leaked from seafloor off the Japanese coast.

PubMed

Kano, Yuki; Sato, Toru; Kita, Jun; Hirabayashi, Shinichiro; Tabeta, Shigeru

2010-02-01

A numerical simulation was conducted to predict the change of pCO(2) in the ocean caused by CO(2) leaked from an underground aquifer, in which CO(2) is purposefully stored. The target space of the present model was the ocean above the seafloor. The behavior of CO(2) bubbles, their dissolution, and the advection-diffusion of dissolved CO(2) were numerically simulated. Here, two cases for the leakage rate were studied: an extreme case, 94,600 t/y, which assumed that a large fault accidentally connects the CO(2) reservoir and the seafloor; and a reasonable case, 3800 t/y, based on the seepage rate of an existing EOR site. In the extreme case, the calculated increase in DeltapCO(2) experienced by floating organisms was less than 300 ppm, while that for immobile organisms directly over the fault surface periodically exceeded 1000 ppm, if momentarily. In the reasonable case, the calculated DeltapCO(2) and pH were within the range of natural fluctuation. Copyright 2009 Elsevier Ltd. All rights reserved.

Plant Operation: Exterior Maintenance, Work Hours

ERIC Educational Resources Information Center

Nation's Schools and Colleges, 1975

1975-01-01

A pitched roof built over a flat roof prevented leaking at a Vermont school. The University of New Hampshire paint shop has a flexible scheduling system that allows employees to choose their work hours each day. (Author/MLF)

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study.

PubMed

Nakamura, Maria Aparecida Miyuki; Costa, Eduardo Leite Vieira; Carvalho, Carlos Roberto Ribeiro; Tucci, Mauro Roberto

2014-01-01

Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

Measuring Air Leaks into the Vacuum Space of Large Liquid Hydrogen Tanks

NASA Technical Reports Server (NTRS)

Youngquist, Robert; Starr, Stanley; Nurge, Mark

2012-01-01

Large cryogenic liquid hydrogen tanks are composed of inner and outer shells. The outer shell is exposed to the ambient environment while the inner shell holds the liquid hydrogen. The region between these two shells is evacuated and typically filled with a powderlike insulation to minimize radiative coupling between the two shells. A technique was developed for detecting the presence of an air leak from the outside environment into this evacuated region. These tanks are roughly 70 ft (approx. equal 21 m) in diameter (outer shell) and the inner shell is roughly 62 ft (approx. equal 19 m) in diameter, so the evacuated region is about 4 ft (approx. equal 1 m) wide. A small leak's primary effect is to increase the boil-off of the tank. It was preferable to install a more accurate fill level sensor than to implement a boil-off meter. The fill level sensor would be composed of an accurate pair of pressure transducers that would essentially weigh the remaining liquid hydrogen. This upgrade, allowing boil-off data to be obtained weekly instead of over several months, is ongoing, and will then provide a relatively rapid indication of the presence of a leak.

A Fiber-Optic Sensor for Leak Detection in a Space Environment

NASA Technical Reports Server (NTRS)

Sinko, John E.; Korman, Valentin; Hendrickson, Adam; Polzin, Kurt A.

2009-01-01

A miniature fiber-optic, laser-based, interferometric leak detector is presented for application as a means to detect on-orbit gas leaks. The sensor employs a fiber-coupled modified Michelson interferometer to detect gas leaks by measuring an increase in gas density in the sensing region. Monitoring changes in the fringe pattern output by the interferometer allows for direct measurement of the gas density in the sensing region and, under the assumption of an equation of state, this can be used to obtain a pressure measurement. Measurements obtained over a pressure range from 20 mtorr to 760 torr using a prototypical interferometer on working gases of air, nitrogen, argon, and helium generally exhibit agreement with a theoretical prediction of the pressure increase required before an interference fringe completely moves over the detector. Additional measurements performed on various gases demonstrate the range of detectable species, measuring sub-torr pressure changes in the process. A high-fidelity measurement places the ultimate pressure resolution for this particular sensor configuration in the 10 mtorr range. Time-resolved data prove the capability of this sensor to detect fast gas flow phenomena associated with transients and pressure waves.

A new tool for the rapid remote detection of leaks from subsea pipelines during remotely operated vehicle inspections

NASA Astrophysics Data System (ADS)

McStay, D.; McIlroy, J.; Forte, A.; Lunney, F.; Greenway, T.; Thabeth, K.; Dean, G.

2005-06-01

A new 2000 m depth rated subsea sensor that can effectively, rapidly and remotely detect leaks of fluorescein dye, leak detection chemicals and hydraulic fluids from underwater structures is reported. The system utilizes ultra-bright LED technology to project a structured beam of light, at a wavelength suitable to excite the fluorescence of the target material, into the water column. The resultant fluorescence is collected and digital signal processing used to extract the intensity. The system is capable of detecting ppm concentrations of fluorescein at a range of 2.5 m in water in real time. The ability to stand-off from subsea structures, while rapidly detecting the chemicals makes the system highly suited to subsea leak inspections with remotely operated vehicles or autonomous underwater vehicles, as it allows the vehicles to be flown quickly and safely over the structure to be inspected. This increases both the speed and effectiveness of the inspection. The remote detection capability is also highly effective for probing complex underwater structures. The system has been successfully used in real subsea survey applications and has been found to be effective, user friendly and to dramatically reduce inspection times and hence costs.

Expert system for identification of simultaneous and sequential reactor fuel failures with gas tagging

DOEpatents

Gross, Kenny C.

1994-01-01

Failure of a fuel element in a nuclear reactor core is determined by a gas tagging failure detection system and method. Failures are catalogued and characterized after the event so that samples of the reactor's cover gas are taken at regular intervals and analyzed by mass spectroscopy. Employing a first set of systematic heuristic rules which are applied in a transformed node space allows the number of node combinations which must be processed within a barycentric algorithm to be substantially reduced. A second set of heuristic rules treats the tag nodes of the most recent one or two leakers as "background" gases, further reducing the number of trial node combinations. Lastly, a "fuzzy" set theory formalism minimizes experimental uncertainties in the identification of the most likely volumes of tag gases. This approach allows for the identification of virtually any number of sequential leaks and up to five simultaneous gas leaks from fuel elements.

Cryogenic Feedthrough Test Rig

NASA Technical Reports Server (NTRS)

Skaff, Antony

2009-01-01

The cryogenic feedthrough test rig (CFTR) allows testing of instrumentation feedthroughs at liquid oxygen and liquid hydrogen temperature and pressure extremes (dangerous process fluid) without actually exposing the feedthrough to a combustible or explosive process fluid. In addition, the helium used (inert gas), with cryogenic heat exchangers, exposes the feedthrough to that environment that allows definitive leak rates of feedthrough by typical industry-standard helium mass spectrometers.

Design of load-to-failure tests of high-voltage insulation breaks for ITER's cryogenic network

NASA Astrophysics Data System (ADS)

Langeslag, S. A. E.; Rodriguez Castro, E.; Aviles Santillana, I.; Sgobba, S.; Foussat, A.

2015-12-01

The development of new generation superconducting magnets for fusion research, such as the ITER experiment, is largely based on coils wound with so-called cable-in-conduit conductors. The concept of the cable-in-conduit conductor is based on a direct cooling principle, by supercritical helium, flowing through the central region of the conductor, in close contact with the superconducting strands. Consequently, a direct connection exists between the electrically grounded helium coolant supply line and the highly energised magnet windings. Various insulated regions, constructed out of high-voltage insulation breaks, are put in place to isolate sectors with different electrical potential. In addition to high voltages and significant internal helium pressure, the insulation breaks will experience various mechanical forces resulting from differential thermal contraction phenomena and electro-magnetic loads. Special test equipment was designed, prepared and employed to assess the mechanical reliability of the insulation breaks. A binary test setup is proposed, where mechanical failure is assumed when leak rate of gaseous helium exceeds 10-9·Pa·m3/s. The test consists of a load-to-failure insulation break charging, in tension, while immersed in liquid nitrogen at the temperature of 77 K. Leak tightness during the test is monitored by measuring the leak rate of the gaseous helium, directly surrounding the insulation break, with respect to the existing vacuum inside the insulation break. The experimental setup is proven effective, and various insulation breaks performed beyond expectations.

CARS technique for geological exploration of hydrocarbons deposits

NASA Astrophysics Data System (ADS)

Zhevlakov, A. P.; Bespalov, Victor; Elizarov, V. V.; Grishkanich, A. S.; Kascheev, S. V.; Makarov, E. A.; Bogoslovsky, S. A.; Il'inskiy, A. A.

2014-10-01

We developed a Raman lidar with ultraspectral resolution for automatic airborne monitoring of pipeline leaks and for oil and gas exploration. Experiments were carried out under the CARS circuit. Minimal concentrations of 200 ppb of heavy hydrocarbon gas have been remotely measured in laboratory tests. Test flights indicate that a sensitivity of 6 ppm for methane and 2 ppm for hydrogen sulfide has been reached for leakage detection. As estimations have shown the reliability of heavy hydrocarbon gas detection by the integration method of seismic prospecting and remote laser sensing in CARS circuit can exceed 80%.

Test program, helium II orbital resupply coupling

NASA Technical Reports Server (NTRS)

Hyatt, William S.

1991-01-01

The full scope of this program was to have included development tests, design and production of custom test equipment and acceptance and qualification testing of prototype and protoflight coupling hardware. This program was performed by Ball Aerospace Systems Division, Boulder, Colorado until its premature termination in May 1991. Development tests were performed on cryogenic face seals and flow control devices at superfluid helium (He II) conditions. Special equipment was developed to allow quantified leak detection at large leak rates up to 8.4 x 10(exp -4) SCCS. Two major fixtures were developed and characterized: The Cryogenic Test Fixture (CTF) and the Thermal Mismatch Fixture (Glovebox). The CTF allows the coupling hardware to be filled with liquid nitrogen (LN2), liquid helium (LHe) or sub-cooled liquid helium when hardware flow control valves are either open or closed. Heat leak measurements, internal and external helium leakage measurements, cryogenic proof pressure tests and external load applications are performed in this fixture. Special reusable MLI closures were developed to provide repeatable installations in the CTF. The Thermal Mismatch Fixture allows all design configurations of coupling hardware to be engaged and disengaged while measuring applied forces and torques. Any two hardware components may be individually thermally preconditioned within the range of 117 deg K to 350 deg K prior to engage/disengage cycling. This verifies dimensional compatibility and operation when thermally mismatched. A clean, dry GN2 atmosphere is maintained in the fixture at all times. The first shipset of hardware was received, inspected and cycled at room temperature just prior to program termination.

Pneumostasis of experimental air leaks with a new photopolymerized synthetic tissue sealant.

PubMed

Ranger, W R; Halpin, D; Sawhney, A S; Lyman, M; Locicero, J

1997-09-01

Air leak is a major contributor to increased length of stay and postoperative morbidity following pulmonary surgery. The effectiveness of a new photopolymerized synthetic hydrogel (FocalSeal, Focal, Inc., Lexington, MA) as a sealant for pulmonary air leaks was determined in 10 mongrel dogs (20-35 kg). The animals were anesthetized and underwent left-sided anterolateral thoracotomy with amputation of a 2 x 3-cm segment of the lung apex. Hemostasis was achieved and terminal bronchial openings of 1.5 to 3 mm with vigorous air leaks were identified. After successful injury, the dogs were randomly assigned to sealant (n = 5) or control (n = 5) groups. In treated animals, the sealant was applied by brushing the solution to the cut parenchymal surface and solidified while briefly interrupting ventilation (40-60 seconds) using visible illumination (450-550 nm) from a xenon light source. Controls received no sealant. A single chest tube was maintained at the injury site with a continuous negative pressure of 20 cm of water. All dogs were extubated and allowed to breathe spontaneously under sedation for 24 hours. Chest radiographs were taken postsurgery and presacrifice. All control animals (n = 5) showed persistent vigorous air leak for the duration of the 24-hour observation period. All treated air leaks resolved immediately, and four of five remained sealed throughout the observation period. One leak reappeared after 17 hours due to inadequate sealant thickness over a 3-mm terminal bronchus. Gross evaluation of the treatment group at the end of 24 hours demonstrated intact sealant well adherent to the parenchyma. No evidence of atelectasis or excessive edema was seen, and no sealant-related complications or toxic effects were noted. Radiologically, lungs were fully inflated. Histologic evaluation at 24 hours revealed no evidence of a strong cellular response to the synthetic sealant, and no fibrosis or adhesions were seen, the onset of the healing process was favorable, indicating good biocompatability. In conclusion, this material was found to be an effective means for sealing bronchial and parenchymal air leaks in this model and warrants clinical evaluation.

Field Trial of an Aerosol-Based Enclosure Sealing Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrington, Curtis; Springer, David

2015-09-01

This report presents the results from several demonstrations of a new method for sealing building envelope air leaks using an aerosol sealing process developed by the Western Cooling Efficiency Center at UC Davis. The process involves pressurizing a building while applying an aerosol sealant to the interior. As air escapes through leaks in the building envelope, the aerosol particles are transported to the leaks where they collect and form a seal that blocks the leak. Standard blower door technology is used to facilitate the building pressurization, which allows the installer to track the sealing progress during the installation and automaticallymore » verify the final building tightness. Each aerosol envelope sealing installation was performed after drywall was installed and taped, and the process did not appear to interrupt the construction schedule or interfere with other trades working in the homes. The labor needed to physically seal bulk air leaks in typical construction will not be replaced by this technology. However, this technology is capable of bringing the air leakage of a building that was built with standard construction techniques and HERS-verified sealing down to levels that would meet DOE Zero Energy Ready Homes program requirements. When a developer is striving to meet a tighter envelope leakage specification, this technology could greatly reduce the cost to achieve that goal by providing a simple and relatively low cost method for reducing the air leakage of a building envelope with little to no change in their common building practices.« less

Using coupled hydrogeophysical models and data assimilation to enhance the information content in geoelectrical leak detection

NASA Astrophysics Data System (ADS)

Tso, C. H. M.; Johnson, T. C.; Song, X.; Chen, X.; Binley, A. M.

2017-12-01

Time-lapse electrical resistivity tomography (ERT) measurements provides indirect observation of hydrological processes in the Earth's shallow subsurface at high spatial and temporal resolutions. ERT has been used for a number of decades to detect leaks and monitor the evolution of associated contaminant plumes. However, this has been limited to a few hazardous environmental sites. Furthermore, an assessment of uncertainty in such applications has thus far been neglected, despite the clear need to provide site managers with appropriate information for decision making purposes. There is a need to establish a framework that allows leak detection with uncertainty assessment from geophysical observations. Ideally such a framework should allow the incorporation of additional data sources in order to reduce uncertainty in predictions. To tackle these issues, we propose an ensemble-based data assimilation framework that evaluates proposed hydrological models (i.e. different hydrogeological units, different leak locations and loads) against observed time-lapse ERT measurements. Each proposed hydrological model is run through the parallel coupled hydrogeophysical code PFLOTRAN-E4D (Johnson et al 2016) to obtain simulated ERT measurements. The ensemble of model proposals is then updated based on data misfit. Our approach does not focus on obtaining detailed images of hydraulic properties or plume movement. Rather, it seeks to estimate the contaminant mass discharge (CMD) across a user-defined plane in space probabilistically. The proposed approach avoids the ambiguity in interpreting detailed hydrological processes from geophysical images. The resultant distributions of CMD give a straightforward metric, with realistic uncertainty bounds, for decision making. The proposed framework is also computationally efficient so that it can exploit large, long-term ERT datasets, making it possible to track time-varying loadings of plume sources. In this presentation, we illustrate our framework on synthetic data and field data collected from an ERT trial simulating a leak at the Sellafield nuclear facility in the UK (Kuras et al 2016). We compare our results to interpretation from geophysical inversion and discuss the additional information that hydrological model proposals provide.

Effect of rock rheology on fluid leak- off during hydraulic fracturing

NASA Astrophysics Data System (ADS)

Yarushina, V. M.; Bercovici, D.; Oristaglio, M. L.

2012-04-01

In this communication, we evaluate the effect of rock rheology on fluid leak­off during hydraulic fracturing of reservoirs. Fluid leak-off in hydraulic fracturing is often nonlinear. The simple linear model developed by Carter (1957) for flow of fracturing fluid into a reservoir has three different regions in the fractured zone: a filter cake on the fracture face, formed by solid additives from the fracturing fluid; a filtrate zone affected by invasion of the fracturing fluid; and a reservoir zone with the original formation fluid. The width of each zone, as well as its permeability and pressure drop, is assumed to remain constant. Physical intuition suggests some straightforward corrections to this classical theory to take into account the pressure dependence of permeability, the compressibility or non-Newtonian rheology of fracturing fluid, and the radial (versus linear) geometry of fluid leak­off from the borehole. All of these refinements, however, still assume that the reservoir rock adjacent to the fracture face is non­deformable. Although the effect of poroelastic stress changes on leak-off is usually thought to be negligible, at the very high fluid pressures used in hydraulic fracturing, where the stresses exceed the rock strength, elastic rheology may not be the best choice. For example, calculations show that perfectly elastic rock formations do not undergo the degree of compaction typically seen in sedimentary basins. Therefore, pseudo-elastic or elastoplastic models are used to fit observed porosity profiles with depth. Starting from balance equations for mass and momentum for fluid and rock, we derive a hydraulic flow equation coupled with a porosity equation describing rock compaction. The result resembles a pressure diffusion equation with the total compressibility being a sum of fluid, rock and pore-space compressibilities. With linear elastic rheology, the bulk formation compressibility is dominated by fluid compressibility. But the possibility of permanent, time-independent (plastic) rock deformation significantly increases the pore space compressibility (compaction), which becomes a leading term in the total compressibility. Inclusion of rock and fluid compressibilities in the model can explain both linear and nonlinear leak­off. In particular, inclusion of rock compaction and decompaction may be important for description of naturally fractured and tight gas reservoirs for which very strong dependence of permeability on porosity has been reported. Carter R.D. Derivation of the general equation for estimating the extent of the fractured area. Appendix I of "Optimum fluid characteristics for fracture extension", Drilling and Production Practice, G.C. Howard and C.R.Fast, New York, New York, USA, American Petroleum Institute (1957), 261-269.

40 CFR 60.482-9a - Standards: Delay of repair.

Code of Federal Regulations, 2010 CFR

2010-07-01

... destroyed or recovered in a control device complying with § 60.482-10a. (d) Delay of repair for pumps will... repair is allowed for a leaking pump, valve, or connector that remains in service, the pump, valve, or...

40 CFR 60.482-9a - Standards: Delay of repair.

Code of Federal Regulations, 2012 CFR

2012-07-01

... destroyed or recovered in a control device complying with § 60.482-10a. (d) Delay of repair for pumps will... repair is allowed for a leaking pump, valve, or connector that remains in service, the pump, valve, or...

40 CFR 60.482-9a - Standards: Delay of repair.

Code of Federal Regulations, 2011 CFR

2011-07-01

... destroyed or recovered in a control device complying with § 60.482-10a. (d) Delay of repair for pumps will... repair is allowed for a leaking pump, valve, or connector that remains in service, the pump, valve, or...

Digital logic circuits in yeast with CRISPR-dCas9 NOR gates

PubMed Central

Gander, Miles W.; Vrana, Justin D.; Voje, William E.; Carothers, James M.; Klavins, Eric

2017-01-01

Natural genetic circuits enable cells to make sophisticated digital decisions. Building equally complex synthetic circuits in eukaryotes remains difficult, however, because commonly used components leak transcriptionally, do not arbitrarily interconnect or do not have digital responses. Here, we designed dCas9-Mxi1-based NOR gates in Saccharomyces cerevisiae that allow arbitrary connectivity and large genetic circuits. Because we used the chromatin remodeller Mxi1, our gates showed minimal leak and digital responses. We built a combinatorial library of NOR gates that directly convert guide RNA (gRNA) inputs into gRNA outputs, enabling the gates to be ‘wired' together. We constructed logic circuits with up to seven gRNAs, including repression cascades with up to seven layers. Modelling predicted the NOR gates have effectively zero transcriptional leak explaining the limited signal degradation in the circuits. Our approach enabled the largest, eukaryotic gene circuits to date and will form the basis for large, synthetic, cellular decision-making systems. PMID:28541304

Tracking buoys research for oil spilling with the wireless charging equipment

NASA Astrophysics Data System (ADS)

Cui, Di; Zhao, Ping

2018-03-01

This paper describes thewirelesscharging equipment for achieving oil spill tracking buoys detection in satellite images acquired after tanker accidents or ship oil spill accidents. This information could allow the evolution of residues dumped at sea to be tracked. The validity of this process is demonstrated using several experiment acquired over several regions (Dalian and Tianjin coasts in China), in which a tanker accident has occurred and as a consequence oil spillage has taken place. Thus, this purpose of paper is developed for the active surveillance and rapid response to marine oil spills tracking buoys with wirelesscharging equipmentis important and essential to environment protection. It may appears of leak places for the Wire Charging Equipment for marine oil spills tracking buoys monitoring needs, and achieved instant alarm technology and equipment, guarantees leak occurred timely obtained alarm information. In order toproviding oil spill accidents emergency quickly reaction time and prepared. The maximum degree reduce oil leak and accidents caused influences are ensured.

Large-Scale Liquid Hydrogen Testing of Variable Density Multilayer Insulation with a Foam Substrate

NASA Technical Reports Server (NTRS)

Martin, J. J.; Hastings, L.

2001-01-01

The multipurpose hydrogen test bed (MHTB), with an 18-cu m liquid hydrogen tank, was used to evaluate a combination foam/multilayer combination insulation (MLI) concept. The foam element (Isofoam SS-1171) insulates during ground hold/ascent flight, and allowed a dry nitrogen purge as opposed to the more complex/heavy helium purge subsystem normally required. The 45-layer MLI was designed for an on-orbit storage period of 45 days. Unique WI features include a variable layer density, larger but fewer double-aluminized Mylar perforations for ascent to orbit venting, and a commercially established roll-wrap installation process that reduced assembly man-hours and resulted in a roust, virtually seamless MLI. Insulation performance was measured during three test series. The spray-on foam insulation (SOFI) successfully prevented purge gas liquefaction within the MLI and resulted in the expected ground hold heat leak of 63 W/sq m. The orbit hold tests resulted in heat leaks of 0.085 and 0.22 W/sq m with warm boundary temperatures of 164 and 305 K, respectively. Compared to the best previously measured performance with a traditional MLI system, a 41-percent heat leak reduction with 25 fewer MLI layers was achieved. The MHTB MLI heat leak is half that calculated for a constant layer density MLI.

Covered self-expandable metal stents for benign biliary tract diseases.

PubMed

Baron, Todd H

2011-05-01

Benign biliary diseases are often managed endoscopically using plastic stents. Benign biliary strictures (BBS) respond to placement of multiple large-bore plastic stents, though requiring multiple procedures to place stents, and to exchange stents to prevent and/or treat stent occlusion. Bile leaks close using plastic stents, which divert bile away from the leak into the duodenum. Covered self-expandable metal stents (CSEMS), intended for palliation of malignant biliary obstruction, have been used to treat benign biliary diseases. Advantages include small predeployment and large postexpansion diameters. Lack of imbedding of the metal into the bile duct wall enables removability. For strictures, one CSEMS is inserted without need for dilation and remains in place for up to 6 months. Successful removal has been reported in all cases. Long-term stricture resolution is achieved in up to 92%. Adverse events include migration and new stricture formation. For treatment of complex bile leaks, the covering and large diameter allow successful closure in nearly all cases. Other uses of CSEMS include treatment of postsphincterotomy bleeding and closure of perforations. CSEMS show promise for treatment of BBS and complex biliary leaks. Successful resolution can be achieved in the majority of patients with the advantage of fewer procedures, which offsets their higher cost.

GPR image analysis to locate water leaks from buried pipes by applying variance filters

NASA Astrophysics Data System (ADS)

Ocaña-Levario, Silvia J.; Carreño-Alvarado, Elizabeth P.; Ayala-Cabrera, David; Izquierdo, Joaquín

2018-05-01

Nowadays, there is growing interest in controlling and reducing the amount of water lost through leakage in water supply systems (WSSs). Leakage is, in fact, one of the biggest problems faced by the managers of these utilities. This work addresses the problem of leakage in WSSs by using GPR (Ground Penetrating Radar) as a non-destructive method. The main objective is to identify and extract features from GPR images such as leaks and components in a controlled laboratory condition by a methodology based on second order statistical parameters and, using the obtained features, to create 3D models that allows quick visualization of components and leaks in WSSs from GPR image analysis and subsequent interpretation. This methodology has been used before in other fields and provided promising results. The results obtained with the proposed methodology are presented, analyzed, interpreted and compared with the results obtained by using a well-established multi-agent based methodology. These results show that the variance filter is capable of highlighting the characteristics of components and anomalies, in an intuitive manner, which can be identified by non-highly qualified personnel, using the 3D models we develop. This research intends to pave the way towards future intelligent detection systems that enable the automatic detection of leaks in WSSs.

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study* **

PubMed Central

Nakamura, Maria Aparecida Miyuki; Costa, Eduardo Leite Vieira; Carvalho, Carlos Roberto Ribeiro; Tucci, Mauro Roberto

2014-01-01

Objective: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. Methods: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Results: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. Conclusions: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM. PMID:25029653

The high energy demand of neuronal cells caused by passive leak currents is not a waste of energy.

PubMed

Berndt, Nikolaus; Holzhütter, Hermann-Georg

2013-11-01

It is estimated that maintenance of the resting potential of neurons consumes between 15% (in gray matter) and 44% (in fully myelinated white matter) of the brain's total energy budget [1]. This poses the intriguing question why evolution has not strived to lower the permeability of passive ion channels to cut the high resting-state energy budget of the brain. Based on a conceptual mathematical model of neuronal ion currents and action potential (AP) firing we demonstrate that a neuron endowed with small leak currents and correspondingly low energy consumption by the Na(+)/K(+)-ATPase in the resting state may indeed recapitulate all features of normal AP firing. However, the activation and inactivation of such a "low-energy-cost neuron" turns out to be extremely sensitive to small fluctuation of Na(+) currents associated with Na(+)-dependent secondary-active transport that is indispensable for the metabolic integrity of the cell and neurotransmitter recycling. We provide evidence that sufficiently large leak currents function as important stabilizers of the membrane potential and thus are required to allow robust AP firing. Our simulations suggest that the energy demand of the Na(+)/K(+)-ATPase needed to counterbalance passive leak currents cannot be significantly dropped below observed values.

40 CFR 60.482-9 - Standards: Delay of repair.

Code of Federal Regulations, 2010 CFR

2010-07-01

... destroyed or recovered in a control device complying with § 60.482-10. (d) Delay of repair for pumps will be... allowed for a leaking pump or valve that remains in service, the pump or valve may be considered to be...

40 CFR 60.482-9 - Standards: Delay of repair.

Code of Federal Regulations, 2012 CFR

2012-07-01

... destroyed or recovered in a control device complying with § 60.482-10. (d) Delay of repair for pumps will be... allowed for a leaking pump or valve that remains in service, the pump or valve may be considered to be...

40 CFR 60.482-9 - Standards: Delay of repair.

Code of Federal Regulations, 2011 CFR

2011-07-01

... destroyed or recovered in a control device complying with § 60.482-10. (d) Delay of repair for pumps will be... allowed for a leaking pump or valve that remains in service, the pump or valve may be considered to be...

40 CFR 280.33 - Repairs allowed.

Code of Federal Regulations, 2013 CFR

2013-07-01

... recognized association or an independent testing laboratory. Note: The following codes and standards may be used to comply with paragraph (a) of this section: National Fire Protection Association Standard 30... Practice for the Interior Lining of Existing Steel Underground Storage Tanks”; and National Leak Prevention...

40 CFR 280.33 - Repairs allowed.

Code of Federal Regulations, 2012 CFR

2012-07-01

... recognized association or an independent testing laboratory. Note: The following codes and standards may be used to comply with paragraph (a) of this section: National Fire Protection Association Standard 30... Practice for the Interior Lining of Existing Steel Underground Storage Tanks”; and National Leak Prevention...

40 CFR 280.33 - Repairs allowed.

Code of Federal Regulations, 2014 CFR

2014-07-01

... recognized association or an independent testing laboratory. Note: The following codes and standards may be used to comply with paragraph (a) of this section: National Fire Protection Association Standard 30... Practice for the Interior Lining of Existing Steel Underground Storage Tanks”; and National Leak Prevention...

Geochemical detection of carbon dioxide in dilute aquifers

PubMed Central

2009-01-01

Background Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 103 to 2 × 106 t/yr (0.63 to 1250 t/m2/yr) to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. Results For the scenarios we studied, our simulations show pH and carbonate chemistry are good indicators for leakage of stored CO2 into an overlying aquifer because elevated CO2 yields a more acid pH than the ambient groundwater. CO2 leakage into a dilute groundwater creates a slightly acid plume that can be detected at some distance from the leak source due to groundwater flow and CO2 buoyancy. pH breakthrough curves demonstrate that CO2 leaks can be easily detected for CO2 flux ≥ 104 t/yr within a 15-month time period at a monitoring well screened within a permeable layer 500 m downstream from the vertical gas trace. At lower flux rates, the CO2 dissolves in the aqueous phase in the lower most permeable unit and does not reach the monitoring well. Sustained pumping in a developed aquifer mixes the CO2-affected water with the ambient water and enhances pH signal for small leaks (103 t/yr) and reduces pH signal for larger leaks (≥ 104t/yr). Conclusion The ability to detect CO2 leakage from a storage reservoir to overlying dilute groundwater is dependent on CO2 solubility, leak flux, CO2 buoyancy, and groundwater flow. Our simulations show that the most likely places to detect CO2 are at the base of the confining layer near the water table where CO2 gas accumulates and is transported laterally in all directions, and downstream of the vertical gas trace where groundwater flow is great enough to transport dissolved CO2 laterally. Our simulations show that CO2 may not rise high enough in the aquifer to be detected because aqueous solubility and lateral groundwater transport within the lower aquifer unit exceeds gas pressure build-up and buoyancy needed to drive the CO2 gas upwards. PMID:19323832

Geochemical detection of carbon dioxide in dilute aquifers.

PubMed

Carroll, Susan; Hao, Yue; Aines, Roger

2009-03-26

Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 10(3) to 2 x 10(6) t/yr (0.63 to 1250 t/m2/yr) to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. For the scenarios we studied, our simulations show pH and carbonate chemistry are good indicators for leakage of stored CO2 into an overlying aquifer because elevated CO2 yields a more acid pH than the ambient groundwater. CO2 leakage into a dilute groundwater creates a slightly acid plume that can be detected at some distance from the leak source due to groundwater flow and CO2 buoyancy. pH breakthrough curves demonstrate that CO2 leaks can be easily detected for CO2 flux >or= 10(4) t/yr within a 15-month time period at a monitoring well screened within a permeable layer 500 m downstream from the vertical gas trace. At lower flux rates, the CO2 dissolves in the aqueous phase in the lower most permeable unit and does not reach the monitoring well. Sustained pumping in a developed aquifer mixes the CO2-affected water with the ambient water and enhances pH signal for small leaks (10(3) t/yr) and reduces pH signal for larger leaks (>or= 10(4) t/yr). The ability to detect CO2 leakage from a storage reservoir to overlying dilute groundwater is dependent on CO2 solubility, leak flux, CO2 buoyancy, and groundwater flow. Our simulations show that the most likely places to detect CO2 are at the base of the confining layer near the water table where CO2 gas accumulates and is transported laterally in all directions, and downstream of the vertical gas trace where groundwater flow is great enough to transport dissolved CO2 laterally. Our simulations show that CO2 may not rise high enough in the aquifer to be detected because aqueous solubility and lateral groundwater transport within the lower aquifer unit exceeds gas pressure build-up and buoyancy needed to drive the CO2 gas upwards.

[Anesthesia ventilators].

PubMed

Otteni, J C; Beydon, L; Cazalaà, J B; Feiss, P; Nivoche, Y

1997-01-01

To review anaesthesia ventilators in current use in France by categories of ventilators. References were obtained from computerized bibliographic search. (Medline), recent review articles, the library of the service and personal files. Anaesthesia ventilators can be allocated into three groups, depending on whether they readminister expired gases or not or allow both modalities. Contemporary ventilators provide either constant volume ventilation, or constant pressure ventilation, with or without a pressure plateau. Ventilators readministering expired gases after CO2 absorption, or closed circuit ventilators, are either of a double- or a single-circuit design. Double-circuit ventilators, or pneumatical bag or bellows squeezers, or bag-in-bottle or bellows-in-bottle (or box) ventilators, consist of a primary, or driving circuit (bottle or box) and a secondary or patient circuit (including a bag or a bellows or membrane chambers). Bellows-in-bottle ventilators have either standing bellows ascending at expiration, or hanging bellows, descending at expiration. Ascending bellows require a positive pressure of about 2 cmH2O throughout exhalation to allow the bellows to refill. The expired gas volume is a valuable indicator for leak and disconnection. Descending bellows generate a slight negative pressure during exhalation. In case of leak or disconnection they aspirate ambient air and cannot act therefore as an indicator for integrity of the circuit and the patient connection. Closed circuit ventilators with a single-circuit (patient circuit) include a insufflating device consisting either in a bellows or a cylinder with a piston, operated by a electric or pneumatic motor. As the hanging bellows of the double circuit ventilators, they generate a slight negative pressure during exhalation and aspirate ambient air in case of leak or disconnection. Ventilators not designed for the readministration of expired gases, or open circuit ventilators, are generally stand-alone mechanical ventilators modified to allow the administration of inhalational anaesthetic agents.

Natural seepage of crude oil into the marine environment

USGS Publications Warehouse

Kvenvolden, K.A.; Cooper, C.K.

2003-01-01

Recent global estimates of crude-oil seepage rates suggest that about 47% of crude oil currently entering the marine environment is from natural seeps, whereas 53% results from leaks and spills during the extraction, transportation, refining, storage, and utilization of petroleum. The amount of natural crude-oil seepage is currently estimated to be 600,000 metric tons per year, with a range of uncertainty of 200,000 to 2,000,000 metric tons per year. Thus, natural oil seeps may be the single most important source of oil that enters the ocean, exceeding each of the various sources of crude oil that enters the ocean through its exploitation by humankind.

Waste-to-energy plants face costly emissions-control upgrades

DOE Office of Scientific and Technical Information (OSTI.GOV)

McIlvaine, R.W.

1995-06-01

One treatment method of municipal solid waste, incineration, has fallen in and out of public favor. In the 1970s, emerging consciousness of the threat to groundwater posed by leaking landfills made incineration an attractive option. Prompted by disrupted energy supplies and steeply rising prices, more than 100 municipalities began to generate electricity from the heat produced by burning trash. In the 1990s, the pendulum of public enthusiasm has swung away from incineration. Energy prices have declined dramatically, and safety and siting concerns complicate new projects. A recent Supreme Court decision ruled that municipal incinerator ash must be tested as hazardousmore » waste and disposed accordingly if levels of such pollutants as cadmium and lead exceed Resource Conservation and Recovery Act limits. So-called flow control regulations, which allowed municipalities to apportion garbage disposal to ensure steady supplies to incinerators, also have been struck down. EPA is tackling the issue of air emissions from waste-to-energy and non-energy-producing municipal waste combustors. Emissions guidelines for MWCs and new-source performance standards for new units, proposed Sept. 20 under Sec. 129 of the Clean Air Act Amendments of 1990, are the culmination of a stalled and litigated initiative dating back to the CAA Amendments of 1977.« less

Building America Case Study: Field Trial of an Aerosol-Based Enclosure Sealing Technology, Clovis, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

This report presents the results from several demonstrations of a new method for sealing building envelope air leaks using an aerosol sealing process developed by the Western Cooling Efficiency Center at UC Davis. The process involves pressurizing a building while applying an aerosol sealant to the interior. As air escapes through leaks in the building envelope, the aerosol particles are transported to the leaks where they collect and form a seal that blocks the leak. Standard blower door technology is used to facilitate the building pressurization, which allows the installer to track the sealing progress during the installation and automaticallymore » verify the final building tightness. Each aerosol envelope sealing installation was performed after drywall was installed and taped, and the process did not appear to interrupt the construction schedule or interfere with other trades working in the homes. The labor needed to physically seal bulk air leaks in typical construction will not be replaced by this technology. However, this technology is capable of bringing the air leakage of a building that was built with standard construction techniques and HERS-verified sealing down to levels that would meet DOE Zero Energy Ready Homes program requirements. When a developer is striving to meet a tighter envelope leakage specification, this technology could greatly reduce the cost to achieve that goal by providing a simple and relatively low cost method for reducing the air leakage of a building envelope with little to no change in their common building practices.« less

Investigation of properties of high-performance fiber-reinforced concrete : very early strength, toughness, permeability, and fiber distribution : final report.

DOT National Transportation Integrated Search

2017-01-01

Concrete cracking, high permeability, and leaking joints allow for intrusion of harmful solutions, resulting in concrete deterioration and corrosion of reinforcement in structures. The development of durable, high-performance concretes with limited c...

Expert system for identification of simultaneous and sequential reactor fuel failures with gas tagging

DOEpatents

Gross, K.C.

1994-07-26

Failure of a fuel element in a nuclear reactor core is determined by a gas tagging failure detection system and method. Failures are catalogued and characterized after the event so that samples of the reactor's cover gas are taken at regular intervals and analyzed by mass spectroscopy. Employing a first set of systematic heuristic rules which are applied in a transformed node space allows the number of node combinations which must be processed within a barycentric algorithm to be substantially reduced. A second set of heuristic rules treats the tag nodes of the most recent one or two leakers as background'' gases, further reducing the number of trial node combinations. Lastly, a fuzzy'' set theory formalism minimizes experimental uncertainties in the identification of the most likely volumes of tag gases. This approach allows for the identification of virtually any number of sequential leaks and up to five simultaneous gas leaks from fuel elements. 14 figs.

Bootstrap inversion technique for atmospheric trace gas source detection and quantification using long open-path laser measurements

NASA Astrophysics Data System (ADS)

Alden, Caroline B.; Ghosh, Subhomoy; Coburn, Sean; Sweeney, Colm; Karion, Anna; Wright, Robert; Coddington, Ian; Rieker, Gregory B.; Prasad, Kuldeep

2018-03-01

Advances in natural gas extraction technology have led to increased activity in the production and transport sectors in the United States and, as a consequence, an increased need for reliable monitoring of methane leaks to the atmosphere. We present a statistical methodology in combination with an observing system for the detection and attribution of fugitive emissions of methane from distributed potential source location landscapes such as natural gas production sites. We measure long (> 500 m), integrated open-path concentrations of atmospheric methane using a dual frequency comb spectrometer and combine measurements with an atmospheric transport model to infer leak locations and strengths using a novel statistical method, the non-zero minimum bootstrap (NZMB). The new statistical method allows us to determine whether the empirical distribution of possible source strengths for a given location excludes zero. Using this information, we identify leaking source locations (i.e., natural gas wells) through rejection of the null hypothesis that the source is not leaking. The method is tested with a series of synthetic data inversions with varying measurement density and varying levels of model-data mismatch. It is also tested with field observations of (1) a non-leaking source location and (2) a source location where a controlled emission of 3.1 × 10-5 kg s-1 of methane gas is released over a period of several hours. This series of synthetic data tests and outdoor field observations using a controlled methane release demonstrates the viability of the approach for the detection and sizing of very small leaks of methane across large distances (4+ km2 in synthetic tests). The field tests demonstrate the ability to attribute small atmospheric enhancements of 17 ppb to the emitting source location against a background of combined atmospheric (e.g., background methane variability) and measurement uncertainty of 5 ppb (1σ), when measurements are averaged over 2 min. The results of the synthetic and field data testing show that the new observing system and statistical approach greatly decreases the incidence of false alarms (that is, wrongly identifying a well site to be leaking) compared with the same tests that do not use the NZMB approach and therefore offers increased leak detection and sizing capabilities.

40 CFR 280.33 - Repairs allowed.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Practice for the Interior Lining of Existing Steel Underground Storage Tanks”; and National Leak Prevention Association Standard 631, “Spill Prevention, Minimum 10 Year Life Extension of Existing Steel Underground... pipe sections and fittings that have released product as a result of corrosion or other damage must be...

40 CFR 280.33 - Repairs allowed.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Practice for the Interior Lining of Existing Steel Underground Storage Tanks”; and National Leak Prevention Association Standard 631, “Spill Prevention, Minimum 10 Year Life Extension of Existing Steel Underground... pipe sections and fittings that have released product as a result of corrosion or other damage must be...

Greater complexity of liver surgery is not associated with an increased incidence of liver-related complications except for bile leak: an experience with 2,628 consecutive resections.

PubMed

Zimmitti, Giuseppe; Roses, Robert E; Andreou, Andreas; Shindoh, Junichi; Curley, Steven A; Aloia, Thomas A; Vauthey, Jean-Nicolas

2013-01-01

Advances in technique, technology, and perioperative care have allowed for the more frequent performance of complex and extended hepatic resections. The purpose of this study was to determine if this increasing complexity has been accompanied by a rise in liver-related complications. A large prospective single-institution database of patients who underwent hepatic resection was used to identify the incidence of liver-related complications. Liver resections were divided into an early era and a late era with equal number of patients (surgery performed before or after 18 May 2006). Patient characteristics and perioperative factors were compared between the two groups. Between 1997 and 2011, 2,628 hepatic resections were performed, with a 90-day morbidity and mortality rate of 37 and 2 %, respectively. We identified higher rates of repeat hepatectomy (12.2 vs 6.1 %; p < 0.001), two-stage resection (4.0 vs 1 %; p < 0.001), extended right hepatectomy (17.6 vs 14.6 %; p = 0.04), and preoperative portal vein embolization (9.1 vs 5.9 %; p < 0.001) in the late era. The incidence of perihepatic abscess (3.7 vs 2.1 %; p = 0.02) and hemorrhage (0.9 vs 0.3 %; p = 0.045) decreased in the late era and the incidence of hepatic insufficiency (3.1 vs 2.6 %; p = 0.41) remained stable. In contrast, the rate of bile leak increased (5.9 vs 3.7 %; p = 0.011). Independent predictors of bile leak included bile duct resection, extended hepatectomy, repeat hepatectomy, en bloc diaphragmatic resection, and intraoperative transfusion. The complexity of liver surgery has increased over time, with a concomitant increase in bile leak rate. Given the strong association between bile leak and other poor outcomes, the development of novel technical strategies to reduce bile leaks is indicated.

Military Enlistment of Hispanic Youth: Obstacles and Opportunities

DTIC Science & Technology

2008-01-01

17 2.13. Allowable Body Fat Measurements, by Gender and Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.1...exceed the maximum allowed weight are given a body- fat measurement to determine if they exceed the allowable body- fat standards, as shown in Table 2.13...Despite having the most lenient weight standards, the Marine Corps has the most restrictive body- fat requirements. For complete height and weight

4D ERT Monitoring of Subsurface Water Pipe Leakage During a Controlled Field Experiment

NASA Astrophysics Data System (ADS)

Inauen, C.; Chambers, J. E.; Wilkinson, P. B.; Meldrum, P.; Swift, R. T.; Uhlemann, S.; Gunn, D.; Dashwood, B.; Taxil, J.; Curioni, G.

2016-12-01

Locating and delineating leakage from subsurface pipelines is an important task for civil engineers. 4D Electrical Resistivity Tomography (ERT) allows changes in subsurface resistivity to be imaged at a high spatial and temporal resolution in a minimally invasive manner. It is therefore a promising tool to supplement conventional point-sensing techniques to monitor subsurface flow processes. To assess the efficacy of ERT for pipe leakage monitoring several controlled leak experiments were carried out at a test site in Blagdon, Bristol, UK. To simulate the leak, a plastic pipe with a hole was buried below a flat, grassed area at a depth of 0.7 m, representing a standard UK mains water pipe installation. The water table at the site lies well below the surface meaning that the experiment took entirely place in the vadose zone, where changes in resistivity are primarily sensitive to water content variations. The ERT array covered an area of 6.5m x 6.5m around the leak location. Data acquisition was carried out with the BGS PRIME (Proactive Infrastructure Monitoring and Evaluation) system, which facilitates remote scheduling and autonomous ERT data collection and transmission. To obtain the resistivity changes of the subsurface a 4D inversion was carried out using a Gauss-Newton approach with spatial and temporal smoothness constraints. We were able to reliably observe the onset, spread and cessation of the leakage. Measurements from in-situ soil sensors at several depths above and below the leak complemented the ERT data and allowed us to assess their reliability and directly relate them to hydrogeological processes. Moreover, through experimental tests with soil samples from the test area, a Waxman-Smits relation was obtained to directly convert the changes in electrical resistivity to gravimetric soil moisture content. With future experiments on the test site more work is planned towards survey optimization, automated processing and tracking of leakage plumes.

Nanoscale Capillary Flows in Alumina: Testing the Limits of Classical Theory.

PubMed

Lei, Wenwen; McKenzie, David R

2016-07-21

Anodic aluminum oxide (AAO) membranes have well-formed cylindrical channels, as small as 10 nm in diameter, in a close packed hexagonal array. The channels in AAO membranes simulate very small leaks that may be present for example in an aluminum oxide device encapsulation. The 10 nm alumina channel is the smallest that has been studied to date for its moisture flow properties and provides a stringent test of classical capillary theory. We measure the rate at which moisture penetrates channels with diameters in the range of 10 to 120 nm with moist air present at 1 atm on one side and dry air at the same total pressure on the other. We extend classical theory for water leak rates at high humidities by allowing for variable meniscus curvature at the entrance and show that the extended theory explains why the flow increases greatly when capillary filling occurs and enables the contact angle to be determined. At low humidities our measurements for air-filled channels agree well with theory for the interdiffusive flow of water vapor in air. The flow rate of water-filled channels is one order of magnitude less than expected from classical capillary filling theory and is coincidentally equal to the helium flow rate, validating the use of helium leak testing for evaluating moisture flows in aluminum oxide leaks.

Performance of materials used for biological personal protective equipment against blood splash penetration.

PubMed

Shimasaki, Noriko; Shinohara, Katsuaki; Morikawa, Hideki

2017-12-07

For occupational safety, healthcare workers must select and wear appropriate personal protective equipment (PPE), protective clothing, and masks as countermeasures against exposure to infectious body fluids and blood splash. It is important for healthcare workers to ensure the protective performance of each PPE against penetration of pathogens. The International Standards Organization (ISO) 22609 test evaluates the effectiveness of medical facemasks to protect against penetration of splashed synthetic blood. However, in this method, the protective performance is determined only visually, without quantification of leaked liquid volume. Therefore, in this study, we modified the ISO 22609 test method to quantify the volume of leaked liquid and obtain a more accurate assessment of the protection performance. We tested non-woven and woven materials used for masks or protective clothing, and the performance of each material was classified using this new method. We found that the quantity of leaked synthetic blood was dependent on the structural characteristics of each material. These findings will allow healthcare workers to select the most appropriate PPE for a given situation or task.

Performance of materials used for biological personal protective equipment against blood splash penetration

PubMed Central

SHIMASAKI, Noriko; SHINOHARA, Katsuaki; MORIKAWA, Hideki

2017-01-01

For occupational safety, healthcare workers must select and wear appropriate personal protective equipment (PPE), protective clothing, and masks as countermeasures against exposure to infectious body fluids and blood splash. It is important for healthcare workers to ensure the protective performance of each PPE against penetration of pathogens. The International Standards Organization (ISO) 22609 test evaluates the effectiveness of medical facemasks to protect against penetration of splashed synthetic blood. However, in this method, the protective performance is determined only visually, without quantification of leaked liquid volume. Therefore, in this study, we modified the ISO 22609 test method to quantify the volume of leaked liquid and obtain a more accurate assessment of the protection performance. We tested non-woven and woven materials used for masks or protective clothing, and the performance of each material was classified using this new method. We found that the quantity of leaked synthetic blood was dependent on the structural characteristics of each material. These findings will allow healthcare workers to select the most appropriate PPE for a given situation or task. PMID:28978815

Direct Endonasal Approach with Partial Upper Posterior Septectomy. A “Rescue Flap” Technique Modification

PubMed Central

Sotomayor-González, Arturo; Díaz-Martínez, Armando José; Radillo-Gil, Ramón; García-Estrada, Everardo; Morales-Gómez, Jesús Alberto; Palacios-Ortiz, Isaac Jair; Pérez-Cárdenas, Samuel; Arteaga-Treviño, Mauricio; De León, Ángel Martínez-Ponce

2016-01-01

Objective Report a modification of the “rescue flap” technique using a direct endonasal approach with a partial superior septectomy for approaching pituitary tumors developed in our institution. Design Prospective study. Setting Hospital Universitario “Dr. José Eleuterio González,” Universidad Autónoma de Nuevo León. Main Outcome Measures Since April 2015, we have performed 19 cases employing a direct endonasal approach with partial superior septectomy. Results and a technical note are described below. Results Nineteen patients were included in this report. Six patients presented transoperatory cerebrospinal fluid (CSF) leak, so a nasoseptal rescue flap was harvested. No patients developed postoperative CSF leak in this group. Two patients were submitted to a second surgical procedure. Nasoseptal flap was harvested without complications. In both patients, the size of the flap was enough to cover the dural defect and avoid CSF leak. Conclusion Direct endonasal approach with a partial posterior septectomy allows enough exposition of the sphenoidal sinus while preserving the nasoseptal septum with the possibility of a successful rescue flap when needed. PMID:28321383

Direct Endonasal Approach with Partial Upper Posterior Septectomy. A "Rescue Flap" Technique Modification.

PubMed

Sotomayor-González, Arturo; Díaz-Martínez, Armando José; Radillo-Gil, Ramón; García-Estrada, Everardo; Morales-Gómez, Jesús Alberto; Palacios-Ortiz, Isaac Jair; Pérez-Cárdenas, Samuel; Arteaga-Treviño, Mauricio; De León, Ángel Martínez-Ponce

2017-04-01

Objective  Report a modification of the "rescue flap" technique using a direct endonasal approach with a partial superior septectomy for approaching pituitary tumors developed in our institution. Design  Prospective study. Setting  Hospital Universitario "Dr. José Eleuterio González," Universidad Autónoma de Nuevo León. Main Outcome Measures  Since April 2015, we have performed 19 cases employing a direct endonasal approach with partial superior septectomy. Results and a technical note are described below. Results  Nineteen patients were included in this report. Six patients presented transoperatory cerebrospinal fluid (CSF) leak, so a nasoseptal rescue flap was harvested. No patients developed postoperative CSF leak in this group. Two patients were submitted to a second surgical procedure. Nasoseptal flap was harvested without complications. In both patients, the size of the flap was enough to cover the dural defect and avoid CSF leak. Conclusion  Direct endonasal approach with a partial posterior septectomy allows enough exposition of the sphenoidal sinus while preserving the nasoseptal septum with the possibility of a successful rescue flap when needed.

Military Enlistment of Hispanic Youth. Obstacles and Opportunities

DTIC Science & Technology

2009-01-01

Weight, by Service, Height, and Gender . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.13. Allowable Body Fat Measurements, by Gender and...has higher minimum weight standards, as seen in Table 2.12. Applicants who exceed the maximum allowed weight are given a body- fat measurement to...determine if they exceed the allowable body- fat standards, as shown in Table 2.13. Despite having the most lenient weight standards, the Marine Corps has

Effect of ADP on slow-twitch muscle fibres of the rat: implications for muscle fatigue.

PubMed

Macdonald, W A; Stephenson, D G

2006-05-15

Slow-twitch mechanically skinned fibres from rat soleus muscle were bathed in solutions mimicking the myoplasmic environment but containing different [ADP] (0.1 microm to 1.0 mm). The effect of ADP on sarcoplasmic reticulum (SR) Ca2+-content was determined from the magnitude of caffeine-induced force responses, while temporal changes in SR Ca2+-content allowed determination of the effective rates of the SR Ca2+-pump and of the SR Ca2+-leak. The SR Ca2+-pump rate, estimated at pCa (-log10[Ca2+]) 7.8, was reduced by 20% as the [ADP] was increased from 0.1 to 40 microm, with no further alteration when the [ADP] was increased to 1.0 mm. The SR Ca2+-leak rate constant was not altered by increasing [ADP] from 0.1 to 40 microm, but was increased by 26% when the [ADP] was elevated to 1.0 mm. This ADP-induced SR Ca2+-leak was insensitive to ruthenium red but was abolished by 2,5-di(tert-butyl)-1,4-hydroquinone (TBQ), indicating that the leak pathway is via the SR Ca2+-pump and not the SR Ca2+-release channel. The decrease in SR Ca2+-pump rate and SR Ca2+-leak rate when [ADP] was increased led to a 40% decrease in SR Ca2+-loading capacity. Elevation of [ADP] had only minor direct effects on the contractile apparatus of slow-twitch fibres. These results suggest that ADP has only limited depressing effects on the contractility of slow-twitch muscle fibres. This is in contrast to the marked effects of ADP on force responses in fast-twitch muscle fibres and may contribute to the fatigue-resistant nature of slow-twitch muscle fibres.

Percutaneous vertebroplasty and bone cement leakage: clinical experience with a new high-viscosity bone cement and delivery system for vertebral augmentation in benign and malignant compression fractures.

PubMed

Anselmetti, Giovanni Carlo; Zoarski, Gregg; Manca, Antonio; Masala, Salvatore; Eminefendic, Haris; Russo, Filippo; Regge, Daniele

2008-01-01

The aim of this study was to assess the feasibility of and venous leakage reduction in percutaneous vertebroplasty (PV) using a new high-viscosity bone cement (PMMA). PV has been used effectively for pain relief in osteoporotic and malignant vertebral fractures. Cement extrusion is a common problem and can lead to complications. Sixty patients (52 female; mean age, 72.2 +/- 7.2) suffering from osteoporosis (46), malignancy (12), and angiomas (2), divided into two groups (A and B), underwent PV on 190 vertebrae (86 dorsal, 104 lumbar). In Group A, PV with high-viscosity PMMA (Confidence, Disc-O-Tech, Israel) was used. This PMMA was injected by a proprietary delivery system, a hydraulic saline-filled screw injector. In Group B, a standard low-viscosity PMMA was used. Postprocedural CT was carried out to detect PMMA leakages and complications. Fisher's exact test and Wilcoxon rank test were used to assess significant differences (p < 0.05) in leakages and to evaluate the clinical outcome. PV was feasible, achieving good clinical outcome (p < 0.0001) without major complications. In Group A, postprocedural CT showed an asymptomatic leak in the venous structures of 8 of 98 (8.2%) treated vertebrae; a discoidal leak occurred in 6 of 98 (6.1%). In Group B, a venous leak was seen in 38 of 92 (41.3%) and a discoidal leak in 12 of 92 (13.0%). Reduction of venous leak obtained by high-viscosity PMMA was highly significant (p < 0.0001), whereas this result was not significant (p = 0.14) related to the disc. The high-viscosity PMMA system is safe and effective for clinical use, allowing a significant reduction of extravasation rate and, thus, leakage-related complications.

Efficacy and safety of a new fully covered self-expandable non-foreshortening metal esophageal stent.

PubMed

Dua, Kulwinder S; Latif, Sahibzada U; Yang, Juliana F; Fang, Tom C; Khan, Abdul; Oh, Young

2014-10-01

Fully covered esophageal self-expandable metal stents (SEMSs) are potentially removable but can be associated with high migration rates. For precise positioning, non-foreshortening SEMSs are preferred. Recently, a new fully covered non-foreshortening SEMS with anti-migration features was introduced. To evaluate the efficacy and safety of this new esophageal SEMS. Retrospective study. Single, tertiary-care center. Consecutive patients with malignant and benign strictures with dysphagia grade of ≥3 and patients with fistulas/leaks were studied. Stent placement and removal. Technical success in stent deployment/removal, efficacy in relieving dysphagia and sealing fistulas/leaks, and adverse events. Forty-three stents were placed in 35 patients (mean [± standard deviation] age 65 ± 11 years; 31 male), 24 for malignant and 11 for benign (5 strictures, 6 leaks) indications. Technical success in precise SEMS placement was 100%. The after-stent dysphagia grade improved significantly (at 1 week: 1.5 ± 0.7; at 4 weeks: 1.2 ± 0.4; baseline: 3.8 ± 0.4; P < .0001). Twenty stents were removed for clinical indications, with technical success of 100%. All leaks sealed after SEMS placement and did not recur after stent removal. All benign strictures recurred after stent removal. Adverse events included migration (14%), chest pain (11%), and dysphagia from tissue hyperplasia (6%). There was no stent-related mortality. Nonrandomized, single-center study. The new esophageal SEMS was effective in relieving malignant dysphagia, allowed for precise placement, and was easily removable. It was effective in treating benign esophageal fistulas and leaks. Stent-related adverse events were acceptable. Copyright © 2014 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Direct Imaging of Shale Gas Leaks Using Passive Thermal Infrared Hyperspectral Imaging

NASA Astrophysics Data System (ADS)

Marcotte, F.; Chamberland, M.; Morton, V.; Gagnon, M. A.

2017-12-01

Natural gas is an energy resource in great demand worldwide. There are many types of gas fields including shale formations which are common especially in the St-Lawrence Valley (Qc). Regardless of its origin, methane (CH4) is the major component of natural gas. Methane gas is odorless, colorless and highly flammable. It is also an important greenhouse gas. Therefore, dealing efficiently with methane emanations and/or leaks is an important and challenging issue for both safety and environmental considerations. In this regard, passive remote sensing represents an interesting approach since it allows characterization of large areas from a safe location. The high propensity of methane contributing to global warming is mainly because it is a highly infrared-active molecule. For this reason, thermal infrared remote sensing represents one of the best approaches for methane investigations. In order to illustrate the potential of passive thermal infrared hyperspectral imaging for research on natural gas, imaging was carried out on a shale gas leak that unexpectedly happen during a geological survey near Hospital Enfant-Jésus (Québec City) in December 2014. Methane was selectively identified in the scene by its unique infrared signature. The estimated gas column density near the leak source was on the order of 65 000 ppm×m. It was estimated that the methane content in the shale gas is on the order of 6-7 %, which is in good agreement with previous geological surveys carried out in this area. Such leaks represent a very serious situation because such a methane concentration lies within the methane lower/upper explosion limits (LEL-UEL, 5-15 %). The results show how this novel technique could be used for research work dealing with methane gas.

Digital and smart chest drainage systems to monitor air leaks: the birth of a new era?

PubMed

Cerfolio, Robert J; Varela, Gonzalo; Brunelli, Alessandro

2010-08-01

Recently, several companies have manufactured and commercialized new pleural drainage units that incorporate electronic components for the digital quantification of air through chest tubes and, in some instances, pleural pressure assessment. The goal of these systems is to objectify this previously subjective bedside clinical parameter and allow for more objective, consistent measurement of air leaks. The belief is this will lead to quicker and more accurate chest tube management. In addition, some systems feature portable suction devices. These may afford earlier mobilization of patients because the pleural drainage chamber is attached to a battery-powered smart suction device. In this article we review the clinical experiences using these new devices. Copyright 2010 Elsevier Inc. All rights reserved.

A solenoid failure detection system for cold gas attitude control jet valves

NASA Technical Reports Server (NTRS)

Johnston, P. A.

1970-01-01

The development of a solenoid valve failure detection system is described. The technique requires the addition of a radioactive gas to the propellant of a cold gas jet attitude control system. Solenoid failure is detected with an avalanche radiation detector located in the jet nozzle which senses the radiation emitted by the leaking radioactive gas. Measurements of carbon monoxide leakage rates through a Mariner type solenoid valve are presented as a function of gas activity and detector configuration. A cylindrical avalanche detector with a factor of 40 improvement in leak sensitivity is proposed for flight systems because it allows the quantity of radioactive gas that must be added to the propellant to be reduced to a practical level.

Optical leak detection of oxygen using IR-laser diodes

NASA Technical Reports Server (NTRS)

Disimile, P. J.; Fox, C.; Toy, N.

1991-01-01

The ability to accurately measure the concentration of gaseous oxygen and its corresponding flow rate is becoming of greater importance. The technique being presented is based on the principal of light attenuation due to the absorption of radiation by the A-band of oxygen which is located in the 759-770 nm wavelength range. With an ability to measure the change in the light transmission to 0.05 percent, a sensitive optical leak detection system which has a rapid time response is possible. In this research program, the application of laser diode technology and its ability to be temperature tuned to a selected oxygen absorption spectral peak has allowed oxygen concentrations as low as 16,000 ppm to be detected.

Investigation of the phenomenon of electrostatic compromise of a plastic fiber heat exchanger.

PubMed

Elgas, R J

1999-03-01

The use of a new generation of blood oxygenator design using plastic fibers for the heat exchange material is growing. The benefits of a plastic heat exchange material are improved biocompatibility and performance over some of the traditional metals used. During the initial period of clinical use of one of these new oxygenators, there were reports of four blood-to-water leaks. No patient complications were associated with these leaks, but the product was withdrawn from the market. After a thorough evaluation, the cause of the leaks was found to be an electrostatic discharge that occurred within the heat exchanger during priming of the extracorporeal circuit. It was found that an electrostatic potential between the blood path and the water path of the heat exchanger is generated as the prime solution is recirculated by a roller pump with polyvinyl chloride (PVC) pumphead tubing. The magnitude of the potential generated was found to vary with the make and model of the roller pump. If this voltage exceeds the dielectric strength of the fiber, a discharge through the wall of a single heat exchange fiber will occur and produce a hole. Several solutions to this problem of roller pumps generating an electrostatic charge when used with PVC pumphead tubing were identified. Centrifugal blood pumps and roller pumps using silicone rubber pumphead tubing were found to generate no significant electrostatic potential between the blood path and the water path. Another solution, a charge equalization line (CEL), was designed to provide a conductive path for the charge to equilibrate across the fiber wall. The CEL can be either external or internal to the oxygenator. Each of these solutions was validated and the product has been reintroduced for clinical use.

Routine postoperative upper gastrointestinal series after Roux-en-Y gastric bypass: determination of whether it is necessary.

PubMed

Kolakowski, Stephen; Kirkland, Matt L; Schuricht, Alan L

2007-10-01

To evaluate the clinical utility of the routine use of postoperative barium swallow to diagnose postoperative complications in patients undergoing open or laparoscopic Roux-en-Y gastric bypass. A total of 417 consecutive patients undergoing Roux-en-Y gastric bypass at our institution between January 1, 2001, and December 31, 2002, were included. We performed 341 open procedures and 76 laparoscopic gastric bypasses. All patients received a limited postoperative fluoroscopic upper gastrointestinal series, except for the patients who exceeded the weight limitation of the radiologic equipment. Radiologic findings of anastomotic complications were anastomotic leak, delayed gastric emptying, gastric outlet obstruction, and gastrogastric fistula. We evaluated clinical signs and symptoms to obtain a list of criteria suggesting these complications. Patients were stratified into 2 groups: those with and those without radiographic anastomotic complications. Clinical and radiologic criteria were compared using univariate and multivariate logistic regression analysis. We noted 42 radiologic abnormalities during a routine postoperative barium swallow evaluation. Among our 417 patients, we documented 12 leaks (2.9%), 19 cases of delayed gastric emptying (4.6%), 4 gastric outlet obstructions (1.0%), and 7 gastrogastric fistulas (1.7%). The combination of fever, tachycardia, and tachypnea was the most specific indicator of a leak, at 0.99 (95% confidence limit, 0.99, 1.01). Nausea with vomiting was the most predictive indicator of delayed gastric emptying and gastric outlet obstruction, with a specificity of 0.99 (95% confidence limit, 0.98, 0.99) and 0.97 (95% confidence limit, 0.96, 0.99), respectively. Postoperative complications after Roux-en-Y gastric bypass surgery are predictable based on the patient's symptoms. The use of routine postoperative fluoroscopic upper gastrointestinal series is unnecessary in asymptomatic patients.

Double-Shell Tank Visual Inspection Changes Resulting from the Tank 241-AY-102 Primary Tank Leak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Girardot, Crystal L.; Washenfelder, Dennis J.; Johnson, Jeremy M.

2013-11-14

As part of the Double-Shell Tank (DST) Integrity Program, remote visual inspections are utilized to perform qualitative in-service inspections of the DSTs in order to provide a general overview of the condition of the tanks. During routine visual inspections of tank 241-AY-102 (AY-102) in August 2012, anomalies were identified on the annulus floor which resulted in further evaluations. In October 2012, Washington River Protection Solutions, LLC determined that the primary tank of AY-102 was leaking. Following identification of the tank AY-102 probable leak cause, evaluations considered the adequacy of the existing annulus inspection frequency with respect to the circumstances ofmore » the tank AY-102 1eak and the advancing age of the DST structures. The evaluations concluded that the interval between annulus inspections should be shortened for all DSTs, and each annulus inspection should cover > 95 percent of annulus floor area, and the portion of the primary tank (i.e., dome, sidewall, lower knuckle, and insulating refractory) that is visible from the annulus inspection risers. In March 2013, enhanced visual inspections were performed for the six oldest tanks: 241-AY-101, 241-AZ-101,241-AZ-102, 241-SY-101, 241-SY-102, and 241-SY-103, and no evidence of leakage from the primary tank were observed. Prior to October 2012, the approach for conducting visual examinations of DSTs was to perform a video examination of each tank's interior and annulus regions approximately every five years (not to exceed seven years between inspections). Also, the annulus inspection only covered about 42 percent of the annulus floor.« less

Intraoperative leak testing has no correlation with leak after laparoscopic sleeve gastrectomy.

PubMed

Sethi, Monica; Zagzag, Jonathan; Patel, Karan; Magrath, Melissa; Somoza, Eduardo; Parikh, Manish S; Saunders, John K; Ude-Welcome, Aku; Schwack, Bradley F; Kurian, Marina S; Fielding, George A; Ren-Fielding, Christine J

2016-03-01

Staple line leak is a serious complication of sleeve gastrectomy. Intraoperative methylene blue and air leak tests are routinely used to evaluate for leak; however, the utility of these tests is controversial. We hypothesize that the practice of routine intraoperative leak testing is unnecessary during sleeve gastrectomy. A retrospective cohort study was designed using a prospectively collected database of seven bariatric surgeons from two institutions. All patients who underwent sleeve gastrectomy from March 2012 to November 2014 were included. The performance of intraoperative leak testing and the type of test (air or methylene blue) were based on surgeon preference. Data obtained included BMI, demographics, comorbidity, presence of intraoperative leak test, result of test, and type of test. The primary outcome was leak rate between the leak test (LT) and no leak test (NLT) groups. SAS version 9.4 was used for univariate and multivariate analyses. A total of 1550 sleeve gastrectomies were included; most were laparoscopic (99.8%), except for one converted and two open cases. Routine intraoperative leak tests were performed in 1329 (85.7%) cases, while 221 (14.3%) did not have LTs. Of the 1329 cases with LTs, there were no positive intraoperative results. Fifteen (1%) patients developed leaks, with no difference in leak rate between the LT and NLT groups (1 vs. 1%, p = 0.999). After adjusting for baseline differences between the groups with a propensity analysis, the observed lack of association between leak and intraoperative leak test remained. In this cohort, leaks presented at a mean of 17.3 days postoperatively (range 1-67 days). Two patients with staple line leaks underwent repeat intraoperative leak testing at leak presentation, and the tests remained negative. Intraoperative leak testing has no correlation with leak due to laparoscopic sleeve gastrectomy and is not predictive of the later development of staple line leak.

Evaluation of an Interferometric Sensor for In-Space Detection of Gas Leaks

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Korman, Valentin; Sinko, John; Hendrickson, Adam

2009-01-01

Space mission planning often involves long-term storage of volatile liquids or high-pressure gases. These may include cryogenic fuels and oxidizers, high-pressure gases, and life-support-critical consumables. The risk associated with the storage of fluids and gases in space systems has long been an issue and the ability to retain these fluids is often tied to mission success. A leak in the storage or distribution system can cause many different problems, including a simple, but mission endangering, loss of inventory or, in severe cases, unbalanced thrust loads on a flight vehicle. Cryogenic propellants are especially difficult to store, especially over a long duration. The propellant can boil off and be lost through the insulating walls of the tank or simple thermal cycling of the fittings, valves, and propellant feed lines may unseat seals allowing the fluid to escape. Current NASA missions call for long-duration in-space storage of propellants, oxidizers, and life support supplies. Leaks of a scale detectable through a pressure drop in the storage tank are often catastrophic and have long been the focus of ground-based mitigation efforts where redundant systems are often employed. However, there is presently no technology available for detecting and monitoring low-level, but still mission-endangering, gas leaks in space. Standard in-space gas detection methods either have a very limited pressure range over which they operate effectively or are limited to certain gases. Mass spectrometer systems are able to perform the detection tasks, but their size, mass and use of high voltage, which could potentially lead to an arc that ignites a combustible propellent, severely limit their usefulness in a space system. In this paper, we present results from testing of the light-based interferometric gas monitoring and leak detection sensor shown in Fig. 1. The output of the sensor is an interference fringe pattern that is a function of the gas density, and commensurate index of refraction, in the sample region. Changes in the density of gas cause the interference fringes to move across a photodiode detector, providing a temporal history of the leak. The sensor is fiber coupled and constructed from solid optics, allowing for placement almost anywhere on the spacecraft. It is also advantageous in that it consumes very little power and does not introduce an ignition source. Data are presented demonstrating the capability of the sensor to measure density variations in different gas species. In addition, the transient response of the sensor in vacuum is demonstrated. These data extend and improve upon the results previously presented by the authors in Ref. [1].

Functional characterization and modified rescue of novel AE1 mutation R730C associated with overhydrated cation leak stomatocytosis.

PubMed

Stewart, Andrew K; Kedar, Prabhakar S; Shmukler, Boris E; Vandorpe, David H; Hsu, Ann; Glader, Bertil; Rivera, Alicia; Brugnara, Carlo; Alper, Seth L

2011-05-01

We report the novel, heterozygous AE1 mutation R730C associated with dominant, overhydrated, cation leak stomatocytosis and well-compensated anemia. Parallel elevations of red blood cell cation leak and ouabain-sensitive Na(+) efflux (pump activity) were apparently unaccompanied by increased erythroid cation channel-like activity, and defined ouabain-insensitive Na(+) efflux pathways of nystatin-treated cells were reduced. Epitope-tagged AE1 R730C at the Xenopus laevis oocyte surface exhibited severely reduced Cl(-) transport insensitive to rescue by glycophorin A (GPA) coexpression or by methanethiosulfonate (MTS) treatment. AE1 mutant R730K preserved Cl(-) transport activity, but R730 substitution with I, E, or H inactivated Cl(-) transport. AE1 R730C expression substantially increased endogenous oocyte Na(+)-K(+)-ATPase-mediated (86)Rb(+) influx, but ouabain-insensitive flux was minimally increased and GPA-insensitive. The reduced AE1 R730C-mediated sulfate influx did not exhibit the wild-type pattern of stimulation by acidic extracellular pH (pH(o)) and, unexpectedly, was partially rescued by exposure to sodium 2-sulfonatoethyl methanethiosulfonate (MTSES) but not to 2-aminoethyl methanethiosulfonate hydrobromide (MTSEA) or 2-(trimethylammonium)ethyl methanethiosulfonate bromide (MTSET). AE1 R730E correspondingly exhibited acid pH(o)-stimulated sulfate uptake at rates exceeding those of wild-type AE1 and AE1 R730K, whereas mutants R730I and R730H were inactive and pH(o) insensitive. MTSES-treated oocytes expressing AE1 R730C and untreated oocytes expressing AE1 R730E also exhibited unprecedented stimulation of Cl(-) influx by acid pH(o). Thus recombinant cation-leak stomatocytosis mutant AE1 R730C exhibits severely reduced anion transport unaccompanied by increased Rb(+) and Li(+) influxes. Selective rescue of acid pH(o)-stimulated sulfate uptake and conferral of acid pH(o)-stimulated Cl(-) influx, by AE1 R730E and MTSES-treated R730C, define residue R730 as critical to selectivity and regulation of anion transport by AE1.

Methyl tert‐butyl ether degradation in the unsaturated zone and the relation between MTBE in the atmosphere and shallow groundwater

USGS Publications Warehouse

Baehr, Arthur L.; Charles, Emmanuel G.; Baker, Ronald J.

2001-01-01

Atmospheric methyl tert‐butyl ether (MTBE) concentrations in southern New Jersey generally exceeded concentrations in samples taken from the unsaturated zone. A simple unsaturated zone transport model indicates that MTBE degradation can explain the attenuation with half‐lives from a few months to a couple of years. Tert‐butyl alcohol (TBA), a possible degradation product of MTBE, was detected in unsaturated‐zone samples at concentrations exceeding atmospheric levels at some sites, suggesting the possible conversion of MTBE to TBA. At sites where MTBE was detected in shallow groundwater, the concentration was typically higher than the overlying unsaturated‐zone concentration. This observation is consistent with outgassing from the aquifer and combined with the unsaturated‐zone attenuation suggests some of the MTBE detections in shallow groundwater are nonatmospheric in origin, coming from leaking tanks, road runoff, or other sources. The identification of sources of MTBE in groundwater and attenuation mechanisms through the hydrologic cycle is critical in developing an understanding of the long‐term effect of MTBE releases.

High energy density capacitors for vacuum operation with a pulsed plasma load

NASA Technical Reports Server (NTRS)

Guman, W. J.

1976-01-01

Results of the effort of designing, fabricating, and testing of a 40 joules/lb (88.2 joules/Kg) high voltage energy storage capacitor suitable for operating a pulsed plasma thruster in a vacuum environment for millions of pulses are presented. Using vacuum brazing and heli-arc welding techniques followed by vacuum and high pressure helium leak tests it was possible to produce a hermetically sealed relatively light weight enclosure for the dielectric system. An energy density of 40 joules/lb was realized with a KF-polyvinylidene fluoride dielectric system. One capacitor was D.C. life tested at 4 KV (107.8 joules/lb) for 2,000 hours before it failed. Another exceeded 2,670 hours without failure at 38.3 joules/lb. Pulse life testing in a vacuum exceeded 300,000 discharges with testing still in progress. The D.C. life test data shows a small decrease in capacitance and an increase in dissipation factor with time. Heat transfer from the load to the capacitor must also be considered besides the self-heat generated by the capacitor.

The Application of a Jet Fan for the Control of Air and Methane Streams Mixing at the Excavations Cross - The Results of Numerical Simulation

NASA Astrophysics Data System (ADS)

Wrona, Paweł; Różański, Zenon; Pach, Grzegorz; Domagała, Lech

2016-09-01

The paper presents the results of numerical simulations into the distribution of methane concentration at the intersection of two excavations with a fan (turned on) giving the air stream to the area of the crossing. Assumed case represents emergency situation related to the unexpected flow of methane from an excavation and its mixing with fresh air. It is possible when sudden gas outburst takes place, methane leaks from methane drainage system or gas leaks out the pipelines of underground coal gasification devices. Three options were considered - corresponding to three different speeds of the jet fan. They represent three stages of fan work. First - low air speed is forced by a pneumatic fan, when electricity is cut off after high methane concentration detection. Medium speed can be forced by pneumatic-electric device when methane concentration allows to turn on the electricity. Third, the highest speed is for electric fans. Simulations were carried out in the Fire Dynamics Simulator (FDS) belongs to the group of programs Computational Fluid Dynamics (CFD). The governing equations are being solved in a numerical way. It was shown that proposed solution allows partial dilution of methane in every variant of speed what should allow escape of the miners from hazardous area.

21st International Conference on DNA Computing and Molecular Programming

DTIC Science & Technology

2016-05-24

ratio [24], which allows plants to ration starch reserves during seasonally changing nights . 28 N. Dalchau et al. We specify the division problem...design of leak- resistant DSD systems. T his motif forms t he basis of a number of DSD schemes t hat do not rely on toehold sequestration alone to prevent

75 FR 68693 - Airworthiness Directives; Airbus Model A380-800 Series Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-09

... may lead to a degraded leak detection capability have been reported. In case of hot air leakage, the... inspection in production and on in-service aircraft, a number of OverHeat Detection System (OHDS... could allow undetected leakage of bleed air from the hot engine/auxiliary power unit causing damage to...

Propionate induces cell swelling and K+ accumulation in shark rectal gland

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feldman, G.M.; Ziyadeh, F.N.; Mills, J.W.

1989-08-01

Small organic anions have been reported to induce cell solute accumulation and swelling. To investigate the mechanism of swelling, we utilized preparations of rectal gland cells from Squalus acanthias incubated in medium containing propionate. Propionate causes cells to swell by diffusing across membranes in its nonionic form, acidifying cell contents, and activating the Na+-H+ antiporter. The Na+-H+ exchange process tends to correct intracellular pH (pHi), and thus it maintains a favorable gradient for propionic acid diffusion and allows propionate to accumulate. Activation of the Na+-H+ antiport also facilitates Na+ entry into the cell and Nai accumulation. At the same timemore » Na+-K+-ATPase activity, unaffected by propionate, replaces Nai with Ki, whereas the K+ leak rate, decreased by propionate, allows Ki to accumulate. As judged by {sup 86}Rb+ efflux, the reduction in K+ leak was not due to propionate-induced cell acidification or reduction in Cli concentration. Despite inducing cell swelling, propionate did not disrupt cell structural elements and F actin distribution along cell membranes.« less

Extensive traumatic anterior skull base fractures with cerebrospinal fluid leak: classification and repair techniques using combined vascularized tissue flaps.

PubMed

Archer, Jacob B; Sun, Hai; Bonney, Phillip A; Zhao, Yan Daniel; Hiebert, Jared C; Sanclement, Jose A; Little, Andrew S; Sughrue, Michael E; Theodore, Nicholas; James, Jeffrey; Safavi-Abbasi, Sam

2016-03-01

This article introduces a classification scheme for extensive traumatic anterior skull base fracture to help stratify surgical treatment options. The authors describe their multilayer repair technique for cerebrospinal fluid (CSF) leak resulting from extensive anterior skull base fracture using a combination of laterally pediculated temporalis fascial-pericranial, nasoseptal-pericranial, and anterior pericranial flaps. Retrospective chart review identified patients treated surgically between January 2004 and May 2014 for anterior skull base fractures with CSF fistulas. All patients were treated with bifrontal craniotomy and received pedicled tissue flaps. Cases were classified according to the extent of fracture: Class I (frontal bone/sinus involvement only); Class II (extent of involvement to ethmoid cribriform plate); and Class III (extent of involvement to sphenoid bone/sinus). Surgical repair techniques were tailored to the types of fractures. Patients were assessed for CSF leak at follow-up. The Fisher exact test was applied to investigate whether the repair techniques were associated with persistent postoperative CSF leak. Forty-three patients were identified in this series. Thirty-seven (86%) were male. The patients' mean age was 33 years (range 11-79 years). The mean overall length of follow-up was 14 months (range 5-45 months). Six fractures were classified as Class I, 8 as Class II, and 29 as Class III. The anterior pericranial flap alone was used in 33 patients (77%). Multiple flaps were used in 10 patients (3 salvage) (28%)--1 with Class II and 9 with Class III fractures. Five (17%) of the 30 patients with Class II or III fractures who received only a single anterior pericranial flap had persistent CSF leak (p < 0.31). No CSF leak was found in patients who received multiple flaps. Although postoperative CSF leak occurred only in high-grade fractures with single anterior flap repair, this finding was not significant. Extensive anterior skull base fractures often require aggressive treatment to provide the greatest long-term functional and cosmetic benefits. Several vascularized tissue flaps can be used, either alone or in combination. Vascularized flaps are an ideal substrate for cranial base repair. Dual and triple flap techniques that combine the use of various anterior, lateral, and nasoseptal flaps allow for a comprehensive arsenal in multilayered skull base repair and salvage therapy for extensive and severe fractures.

Method Development for Container Closure Integrity Evaluation via Headspace Gas Ingress by Using Frequency Modulation Spectroscopy.

PubMed

Victor, Ken G; Levac, Lauren; Timmins, Michael; Veale, James

2017-01-01

USP <1207.1> Section 3.5 states that "A deterministic leak test method having the ability to detect leaks at the product's maximum allowable leakage limit is preferred when establishing the inherent integrity of a container-closure system." Ideally, container closure integrity of parenteral packaging would be evaluated by measuring a physical property that is sensitive to the presence of any package defect that breaches package integrity by increasing its leakage above its maximum allowable leakage limit. The primary goals of the work presented herein were to demonstrate the viability of the nondestructive, deterministic method known as laser-based gas headspace analysis for evaluating container closure integrity and to provide a physical model for predicting leak rates for a variety of container volumes, headspace conditions, and defect sizes. The results demonstrate that laser-based headspace analysis provides sensitive, accurate, and reproducible measurements of the gas ingress into glass vial-stopper package assemblies that are under either diffusive or effusive leak conditions. Two different types of positive controls were examined. First, laser-drilled micro-holes in thin metal disks that were crimped on top of 15R glass vials served as positive controls with a well-characterized defect geometry. For these, a strong correlation was observed between the measured ingress parameter and the size of the defect for both diffusive and effusive conditions. Second, laser-drilled holes in the wall of glass vials served as controls that more closely simulate real-world defects. Due to their complex defect geometries, their diffusive and effusive ingress parameters did not necessarily correlate; this is an important observation that has significant implications for standardizing the characterization of container defects. Regardless, laser-based headspace analysis could readily differentiate positive and negative controls for all leak conditions, and the results provide a guide for method development of container closure integrity tests. LAY ABSTRACT: The new USP 39 <1207>, "Package Integrity Evaluation-Sterile Products", states in section 3.4.1: "tracer gas tests performed using … laser-based gas headspace analysis [have] been shown to be sensitive enough to quantitatively analyze leakage through the smallest leak paths found to pose the smallest chance of liquid leakage or microbial ingress in rigid packaging." In addition, USP <1207> also states that "for such methods, the limit of detection can be mathematically predicted on the basis of gas flow kinetics." Using the above statements as a foundation, this paper presents a theoretical basis for predicting the gas ingress through well-defined defects in product vials sealed under a variety of headspace conditions. These calculated predictions were experimentally validated by comparing them to measurements of changes in the headspace oxygen content or total pressure for several different positive controls using laser-based headspace analysis. The results demonstrated that laser-based headspace analysis can, by readily differentiating between negative controls and positive controls with a range of defect sizes on the micron scale, be used to assess container closure integrity. The work also demontrated that caution must be used when attempting to correlate a leak rate to an idealized defect-size parameter. © PDA, Inc. 2017.

Fugitive methane emissions from leak-prone natural gas distribution infrastructure in urban environments.

PubMed

Hendrick, Margaret F; Ackley, Robert; Sanaie-Movahed, Bahare; Tang, Xiaojing; Phillips, Nathan G

2016-06-01

Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 - 2.3 × 10(4) g CH4•day(-1). The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing 'superemitter' leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as 'safely leaking.' Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Source attribution and quantification of benzene event emissions in a Houston ship channel community based on real-time mobile monitoring of ambient air.

PubMed

Olaguer, Eduardo P; Erickson, Matthew H; Wijesinghe, Asanga; Neish, Bradley S

2016-02-01

A mobile laboratory equipped with a proton transfer reaction mass spectrometer (PTR-MS) operated in Galena Park, Texas, near the Houston Ship Channel during the Benzene and other Toxics Exposure Study (BEE-TEX). The mobile laboratory measured transient peaks of benzene of up to 37 ppbv in the afternoon and evening of February 19, 2015. Plume reconstruction and source attribution were performed using the four-dimensional (4D) variational data assimilation technique and a three-dimensional (3D) micro-scale forward and adjoint air quality model based on mobile PTR-MS data and nearby stationary wind measurements at the Galena Park Continuous Air Monitoring Station (CAMS). The results of inverse modeling indicate that significant pipeline emissions of benzene may at least partly explain the ambient concentration peaks observed in Galena Park during BEE-TEX. Total pipeline emissions of benzene inferred within the 16-km(2) model domain exceeded point source emissions by roughly a factor of 2 during the observational episode. Besides pipeline leaks, the model also inferred significant benzene emissions from marine, railcar, and tank truck loading/unloading facilities, consistent with the presence of a tanker and barges in the Kinder Morgan port terminal during the afternoon and evening of February 19. Total domain emissions of benzene exceeded corresponding 2011 National Emissions Inventory (NEI) estimates by a factor of 2-6. Port operations involving petrochemicals may significantly increase emissions of air toxics from the transfer and storage of materials. Pipeline leaks, in particular, can lead to sporadic emissions greater than in emission inventories, resulting in higher ambient concentrations than are sampled by the existing monitoring network. The use of updated methods for ambient monitoring and source attribution in real time should be encouraged as an alternative to expanding the conventional monitoring network.

Assessment of Pneumatic Controller Emission Measurements ...

EPA Pesticide Factsheets

Oil and Natural Gas (ONG) production facilities have the potential to emit greenhouse gases such as methane (CH4) and other hydrocarbons (HCs) to the atmosphere. ONG production sites have multiple emission sources including storage tank venting, enclosed combustion devices, engine exhaust, pneumatic controllers and uncontrolled leaks. Accounting for up to 37.8 percent of CH4 emissions, pneumatic controllers are one of the most significant sources of CH4 in ONG production field operations. Recent measurement studies used the only commercially-available high volume sampling (HVS) technology (Bacharach Hi Flow Sampler, Bacharach, Inc., New Kensington, PA) to quantify CH4 emission rates of pneumatic devices on ONG production pads and compare to inventory estimates. Other studies indicate that this HVS may malfunction, causing underestimates of emissions in certain scenarios encountered in ONG production and should not be used for some sources such as heavy emissions from condensate storage tanks. The HVS malfunction can occur on relatively large emissions, where the measured leak concentrations exceed 5%, and is ascribed to a sensor transition failure in the instrument. The HVS malfunction is believed to be exacerbated by several factors (large emission rates, amount of non-CH4 HCs in the emission stream, non-optimal HVS calibration frequency, firmware, and emission measurement coupling geometries). The degree to which HVS measurements of emissions from pneumatic co

DOE Office of Scientific and Technical Information (OSTI.GOV)

James K. Neathery; Gary Jacobs; Amitava Sarkar

In the previous reporting period, modifications were completed for integrating a continuous wax filtration system for a 4 liter slurry bubble column reactor. During the current reporting period, a shakedown of the system was completed. Several problems were encountered with the progressive cavity pump used to circulate the wax/catalyst slurry though the cross-flow filter element and reactor. During the activation of the catalyst with elevated temperature (> 270 C) the elastomer pump stator released sulfur thereby totally deactivating the iron-based catalyst. Difficulties in maintaining an acceptable leak rate from the pump seal and stator housing were also encountered. Consequently, themore » system leak rate exceeded the expected production rate of wax; therefore, no online filtration could be accomplished. Work continued regarding the characterization of ultra-fine catalyst structures. The effect of carbidation on the morphology of iron hydroxide oxide particles was the focus of the study during this reporting period. Oxidation of Fe (II) sulfate results in predominantly {gamma}-FeOOH particles which have a rod-shaped (nano-needles) crystalline structure. Carbidation of the prepared {gamma}-FeOOH with CO at atmospheric pressure produced iron carbides with spherical layered structure. HRTEM and EDS analysis revealed that carbidation of {gamma}-FeOOH particles changes the initial nano-needles morphology and generates ultrafine carbide particles with irregular spherical shape.« less

Factors impacting cerebrospinal fluid leak rates in endoscopic sellar surgery.

PubMed

Karnezis, Tom T; Baker, Andrew B; Soler, Zachary M; Wise, Sarah K; Rereddy, Shruthi K; Patel, Zara M; Oyesiku, Nelson M; DelGaudio, John M; Hadjipanayis, Constantinos G; Woodworth, Bradford A; Riley, Kristen O; Lee, John; Cusimano, Michael D; Govindaraj, Satish; Psaltis, Alkis; Wormald, Peter John; Santoreneos, Steve; Sindwani, Raj; Trosman, Samuel; Stokken, Janalee K; Woodard, Troy D; Recinos, Pablo F; Vandergrift, W Alexander; Schlosser, Rodney J

2016-11-01

In patients undergoing transnasal endoscopic sellar surgery, an analysis of risk factors and predictors of intraoperative and postoperative cerebrospinal fluid leak (CSF) would provide important prognostic information. A retrospective review of patients undergoing endoscopic sellar surgery for pituitary adenomas or craniopharyngiomas between 2002 and 2014 at 7 international centers was performed. Demographic, comorbidity, and tumor characteristics were evaluated to determine the associations between intraoperative and postoperative CSF leaks. Correlations between reconstructive and CSF diversion techniques were associated with postoperative CSF leak rates. Odds ratios (OR) were identified using a multivariate logistic regression model. Data were collected on 1108 pituitary adenomas and 53 craniopharyngiomas. Overall, 30.1% of patients had an intraoperative leak and 5.9% had a postoperative leak. Preoperative factors associated with increased intraoperative leaks were mild liver disease, craniopharyngioma, and extension into the anterior cranial fossa. In patients with intraoperative CSF leaks, postoperative leaks occurred in 10.3%, with a higher postoperative leak rate in craniopharyngiomas (20.8% vs 5.1% in pituitary adenomas). Once an intraoperative leak occurred, craniopharyngioma (OR = 4.255, p = 0.010) and higher body mass index (BMI) predicted postoperative leak (OR = 1.055, p = 0.010). In patients with an intraoperative leak, the use of septal flaps reduced the occurrence of postoperative leak (OR = 0.431, p = 0.027). Rigid reconstruction and CSF diversion techniques did not impact postoperative leak rates. Intraoperative CSF leaks can occur during endoscopic sellar surgery, especially in larger tumors or craniopharyngiomas. Once an intraoperative leak occurs, risk factors for postoperative leaks include craniopharyngiomas and higher BMI. Use of septal flaps decreases this risk. © 2016 ARS-AAOA, LLC.

Implementation of Statistical Process Control: Evaluating the Mechanical Performance of a Candidate Silicone Elastomer Docking Seal

NASA Technical Reports Server (NTRS)

Oravec, Heather Ann; Daniels, Christopher C.

2014-01-01

The National Aeronautics and Space Administration has been developing a novel docking system to meet the requirements of future exploration missions to low-Earth orbit and beyond. A dynamic gas pressure seal is located at the main interface between the active and passive mating components of the new docking system. This seal is designed to operate in the harsh space environment, but is also to perform within strict loading requirements while maintaining an acceptable level of leak rate. In this study, a candidate silicone elastomer seal was designed, and multiple subscale test articles were manufactured for evaluation purposes. The force required to fully compress each test article at room temperature was quantified and found to be below the maximum allowable load for the docking system. However, a significant amount of scatter was observed in the test results. Due to the stochastic nature of the mechanical performance of this candidate docking seal, a statistical process control technique was implemented to isolate unusual compression behavior from typical mechanical performance. The results of this statistical analysis indicated a lack of process control, suggesting a variation in the manufacturing phase of the process. Further investigation revealed that changes in the manufacturing molding process had occurred which may have influenced the mechanical performance of the seal. This knowledge improves the chance of this and future space seals to satisfy or exceed design specifications.

The mechanical and microbiological integrity of surgical gloves.

PubMed

Jamal, Ala; Wilkinson, Stephen

2003-03-01

Several manufacturers supply surgical gloves that have been individually tested (IT) for leaks. Other manufacturers supply gloves in which sample gloves from each batch are tested for leaks (batch tested: BT). The latter brands may be rejected by surgeons because of presumed increased risk of wound infection and staff exposure to patient pathogens. The influence of differences between glove brands on performance in surgery has not been extensively studied. The aims of the present study were to test the mechanical and microbiological integrity of IT compared to BT gloves. A total of 110 unused gloves from each of an IT and a BT brand were tested for leaks, first, by observation of water-jets from water-filled gloves and second, by measuring electrical resistance between inside and outside the glove surfaces, to give a baseline measure. A total of 304 IT and 280 BT gloves were then similarly leak-tested after 98 clean surgical procedures. The hands and gloves of scrub team members were cultured postsurgery. A total of 1/110 BT and 0/110 IT unused gloves contained leaks (NS, Fisher's exact test). Operative perforation rates were lower for BT compared with IT (8/280 cf. 22/304; P < 0.05 Fisher's exact test). There was no bias in types of operations or scrub team members to account for the difference. Growth of normal skin flora was found on virtually every wearer's hands post-operatively. Similar bacteria were frequently cultured from the outside of gloves at the conclusion of surgery (111/152 pairs IT cf. 122/140 pairs BT; P < 0.01, Fisher's exact test). This study provides evidence that the clinical performance of BT gloves is no different to IT gloves. There was no significant difference in mechanical leak rates for unused gloves. Paradoxically, although IT gloves were more likely to show macro-perforations after surgery, the incidence of contamination on the surface of BT gloves was greater, possibly reflecting a qualitative difference in glove material. This study suggests that both types of gloves develop microporosity during use, which may allow transfer of bacteria from the surgeon's skin to the surface of the glove.

Prospective randomized trial compares suction versus water seal for air leaks.

PubMed

Cerfolio, R J; Bass, C; Katholi, C R

2001-05-01

Surgeons treat air leaks differently. Our goal was to evaluate whether it is better to place chest tubes on suction or water seal for stopping air leaks after pulmonary surgery. A second goal was to evaluate a new classification system for air leaks that we developed. Patients were prospectively randomized before surgery to receive suction or water seal to their chest tubes on postoperative day (POD) #2. Air leaks were described and quantified daily by a classification system and a leak meter. The air-leak meter scored leaks from 1 (least) to 7 (greatest). The group randomized to water seal stayed on water seal unless a pneumothorax developed. On POD #2, 33 of 140 patients had an air leak. Eighteen patients had been preoperatively randomized to water seal and 15 to suction. Air leaks resolved in 12 (67%) of the water seal patients by the morning of POD #3. All 6 patients whose air leak did not stop had a leak that was 4/7 or greater (p < 0.0001) on the leak meter. Of the 15 patients randomized to suction, only 1 patient's air leak (7%) resolved by the morning of POD #3. The randomization aspect of the trial was ended and statistical analysis showed water seal was superior (p = 0.001). The remaining 14 patients were then placed to water seal and by the morning of POD #4, 13 patients' leaks had stopped. Of the 32 total patients placed to seal, 7 (22%) developed a pneumothorax and 6 of these 7 patients had leaks that were 4/7 or greater (p = 0.001). Placing chest tubes on water seal seems superior to wall suction for stopping air leaks after pulmonary resection. However, water seal does not stop expiratory leaks that are 4/7 or greater. Pneumothorax may occur when chest tubes are placed on seal with leaks this large.

Full-Scale System for Quantifying Loads and Leak Rates of Seals for Space Applications

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.; Steinetz, Bruce M.; Daniels, Christopher C.; Wasowski, Janice L.; Robbie, Malcolm G.; Erker, Arthur H.; Drlik, Gary J.; Mayer, John J.

2010-01-01

NASA is developing advanced space-rated vacuum seals in support of future space exploration missions to low-Earth orbit and other destinations. These seals may be 50 to 60 in. (127 to 152 cm) in diameter and must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air for extended missions to the International Space Station or the Moon. Seal compression loads must be below prescribed limits so as not to overload the mechanisms that compress them during docking or mating, and seal adhesion forces must be low to allow two mated systems to separate when required. NASA Glenn Research Center has developed a new test apparatus to measure leak rates and compression and adhesion loads of candidate full-scale seals under simulated thermal, vacuum, and engagement conditions. Tests can be performed in seal-on-seal or seal-on-flange configurations at temperatures from -76 to 140 F (-60 to 60 C) under operational pressure gradients. Nominal and off-nominal mating conditions (e.g., incomplete seal compression) can also be simulated. This paper describes the main design features of the test apparatus as well as techniques used to overcome some of the design challenges.

40 CFR 86.1111-87 - Test procedures for PCA testing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... supply to the chemiluminescent analyzers is placed in the standby position.] (B) The manufacturer shall... manufacturer shall inspect the fuel system to insure the absence of any leaks of liquid or vapor to the atmosphere by applying a pressure of 14.5 ±0.5 inches of water to the fuel system, allowing the pressure to...

40 CFR 86.608-98 - Test procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... voltage supply to the chemiluminescent analyzers is placed in the standby position.) (B) The manufacturer... system to ensure the absence of any leaks of liquid or vapor to the atmosphere by applying a pressure of 14.5±0.5 inches of water (3.6±0.1 Kpa) to the fuel system allowing the pressure to stabilize and...

40 CFR 63.11163 - What are the standards and compliance requirements for new sources?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., the Administrator or delegated authority may allow owners and operators more than 3 hours to alleviate... to alleviate this condition within 3 hours of the time the alarm occurs, and demonstrates that the... leak detection system, you must initiate procedures to determine the cause of every alarm within 1 hour...

Pharmaceutical container/closure integrity. I: Mass spectrometry-based helium leak rate detection for rubber-stoppered glass vials.

PubMed

Kirsch, L E; Nguyen, L; Moeckly, C S

1997-01-01

The development of mass spectrometry-based leak detection for pharmaceutical container integrity was undertaken to provide an alternative to microbial challenge testing. Standard 10-mL vials were modified to contain pinholes (0.5 to 10 microns) by affixing micropipettes with epoxy into 2-mm vial side wall holes. The absolute leak rate was determined using vials that were sealed in a tracer (helium) environment with butyl rubber stoppers and crimps. Alternatively leak rates were determined using vials that were sealed in room air and exposed to tracer under pressure (charging or bombing). Tracer leak rates were measured with mass spectrometry leak rate detectors. The absolute leak rate was correlated the squared nominal leak radius which suggested that the mode of gas flow through the glass pipette leaks was more turbulent than viscous even at low leak rates typically associated with viscous flow. The minimum observed absolute leak rate was about 10(-6.6) std cc/sec and was likely due to helium permeation through the rubber stoppers. Heat-stressed rubber stoppers did not affect the baseline absolute leak rate. Adsorption of helium tracer to the test unit surfaces was found to confound baseline leak rate measurement reliability but was eliminated as a source of variation by exposing the test units to ambient air for > or = 12 hours. The absolute leak rate and the leak rate measured after charging were related in a mathematically predictable way.

Non-invasive positive-pressure ventilation with positive end-expiratory pressure counteracts inward air leaks during preoxygenation: a randomised crossover controlled study in healthy volunteers.

PubMed

Hanouz, J-L; Le Gall, F; Gérard, J-L; Terzi, N; Normand, H

2018-04-01

During preoxygenation, the lack of tight fit between the mask and the patient's face results in inward air leak preventing effective preoxygenation. We hypothesized that non-invasive positive-pressure ventilation and positive end-expiratory pressure (PEEP) could counteract inward air leak. Healthy volunteers were randomly assigned to preoxygenated through spontaneous breathing without leak (SB), spontaneous breathing with a calibrated air leak (T-shaped piece between the mouth and the breathing system; SB-leak), or non-invasive positive inspiratory pressure ventilation (inspiratory support +6 cm H 2 O; PEEP +5 cm H 2 O) with calibrated leak (PPV-leak). The volunteers breathed through a mouthpiece connected to an anaesthesia ventilator. The expired oxygen fraction (FeO 2 ) and air-leak flow (ml s -1 ) were measured. The primary end point was the proportion of volunteers with FeO 2 >90% at 3 min. The secondary end points were FeO 2 at 3 min, time to reach FeO 2 of 90%, and the inspiratory air-leak flow. Twenty healthy volunteers were included. The proportion of volunteers with FeO 2 >90% at 3 min was 0% in the SB-leak group, 95% in the SB group, and 100% in the PPV-leak group (P<0.001). At 3 min, the mean [standard deviation (sd)] FeO 2 was 89 (1)%, 76 (1)%, and 90 (0)% in the SB, SB-leak, and PPV-leak groups, respectively (P<0.001). The mean (sd) inward air leak was 59 (12) ml s -1 in the SB-leak group, but 0 (0) ml s -1 in the PPV-leak group (P<0.001). Preoxygenation through non-invasive positive-pressure ventilation and PEEP provided effective preoxygenation despite an inward air leak. NCT03087825. Copyright © 2017 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

Quantum key distribution with untrusted detectors

NASA Astrophysics Data System (ADS)

González, P.; Rebón, L.; Ferreira da Silva, T.; Figueroa, M.; Saavedra, C.; Curty, M.; Lima, G.; Xavier, G. B.; Nogueira, W. A. T.

2015-08-01

Side-channel attacks currently constitute the main challenge for quantum key distribution (QKD) to bridge theory with practice. So far two main approaches have been introduced to address this problem, (full) device-independent QKD and measurement-device-independent QKD. Here we present a third solution that might exceed the performance and practicality of the previous two in circumventing detector side-channel attacks, which arguably is the most hazardous part of QKD implementations. Our proposal has, however, one main requirement: the legitimate users of the system need to ensure that their labs do not leak any unwanted information to the outside. The security in the low-loss regime is guaranteed, while in the high-loss regime we already prove its robustness against some eavesdropping strategies.

Modeling of Lunar Dust Contamination Due to Plume Impingement

NASA Technical Reports Server (NTRS)

Woronowicz, Michael

2009-01-01

During the Apollo missions it became apparent that lunar dust was a significant hazard. Problems included: surface obscuration during landing sequence; abrasion damage to gouge faces and helmet visors; mechanism clogging; development of space suit pressurization leaks; loss of radiator heat rejection capabilities to the point where vulnerable equipment exceeded maximum survival temperature ratings; temporary vision and respiratory problems within the Apollo Lunar Module (LM). NASA Constellation Program features many system-level components, including the Altair Lunar Lander. Altair to endure longer periods at lunar surface conditions: Apollo LM, about three days; Altair, over seven months. Program managers interested in plume-generated dust transport onto thermal control surface radiators of the first Altair created by its own landing operations.

26 CFR 1.6016-1 - Declarations of estimated income tax by corporations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... be expected to exceed the sum of $100,000 plus the amount of any estimated credits allowable under...,000) does not exceed the $100,000 plus the allowable credits totaling $7,000. [T.D. 6768, 29 FR 14921...), or subchapter L, chapter 1 of the Code, over the sum of $100,000 and any estimated credits under...

Clinical and subclinical leaks after low colorectal anastomosis: a clinical and radiologic study.

PubMed

Lim, Michael; Akhtar, Saleem; Sasapu, Kishore; Harris, Keith; Burke, Dermot; Sagar, Peter; Finan, Paul

2006-10-01

This study was designed to examine the natural history of subclinical leaks and their effect on bowel function and quality of life and to evaluate water-soluble contrast enema features that predict anastomotic healing after leaks. Consecutive patients who underwent low rectal anastomosis were followed up postoperatively for leaks. All leaks were confirmed radiologically with CT scanning and water-soluble contrast enema imaging. Water-soluble contrast enemas were serially repeated to identify healing. Characteristics on initial water-soluble contrast enema were correlated with observed healing. Postoperatively, patients were required to fill in a quality of life and a bowel function questionnaire. A total of 138 patients underwent low rectal anastomosis procedures with a median follow-up period of 26 (interquartile range, 19-37) months. There were 23 documented leaks of which 13 (9 percent) presented clinically and 10 (8 percent) presented subclinically. Ileostomy closure was possible in 4 of 13 (30 percent) patients with a clinical leak and all 10 (100 percent) patients with a subclinical leak. Median quality of life scores were lower for patients with clinical leaks and no ileostomy closure (P = 0.03). Bowel function for subclinical leak patients and clinical leak patients with ileostomy closure were similarly impaired. The presence of a cavity (P = 0.01) and a stricture (P = 0.01) at the anastomotic site were unfavorable radiologic features associated with nonhealing. Subclinical leaks are more benign in their natural history compared with clinical leaks. Quality of life and bowel function is no better in patients with a subclinical leak compared with patients with a clinical leak who have ileostomy closure. Anastomotic leaks may resolve if favorable radiologic features are present.

Locating air leaks in manned spacecraft using structure-borne noise.

PubMed

Holland, Stephen D; Chimenti, D E; Roberts, Ron; Strei, Michael

2007-06-01

All manned spacecraft are vulnerable to leaks generated by micrometeorite or debris impacts. Methods for locating such leaks using leak-generated, structure-borne ultrasonic noise are discussed and demonstrated. Cross-correlations of ultrasonic noise waveforms from a leak into vacuum are used to find the location of the leak. Four methods for sensing and processing leak noise have been developed and tested and each of these can be used to reveal the leak location. The methods, based on phased-array, distributed sensor, and dual sensor approaches, utilize the propagation patterns of guided ultrasonic Lamb waves in the spacecraft skin structure to find the source or direction of the leak noise. It is shown that each method can be used to successfully locate the leak to within a few millimeters on a 0.6-m2 aluminum plate. The relative merits of the four methods are discussed.

Endoluminal stenting for the management of leak following sleeve gastrectomy and loop duodenojejunal bypass with sleeve gastrectomy.

PubMed

Tsai, Ying-Nan; Wang, Hsiu-Po; Huang, Chih-Kun; Chang, Po-Chin; Lin, I-Chang; Tai, Chi-Ming

2018-01-01

Postoperative leak is a serious complication of bariatric surgery and often results in significant morbidity and mortality. Stent placement is a less invasive alternative to surgery for the treatment of bariatric surgical leak. We evaluated the efficacy and complications of covered self-expandable metal stents (SEMS) in the treatment of post-bariatric surgical leak. We retrospectively reviewed patients who underwent stent placement for leak after bariatric surgery. Leak was diagnosed by upper gastrointestinal series or was visualized during the endoscopy. We examined the timing of stent placement, size of the leak, stent migration and its complications, total stent treatment duration, and treatment outcome. Between January 2011 and April 2015, seven patients underwent covered SEMS placement for leak after bariatric surgery, including laparoscopic sleeve gastrectomy (LSG) (n = 5) and laparoscopic loop duodenojejunal bypass with sleeve gastrectomy (LDJB-SG) (n = 2). A stent was placed in one patient for infection control and bridging to revisional surgery. Among the other six patients, one patient who received stent placement one year after leak diagnosis failed to achieve leak closure, and five patients with early stent placement achieved leak closure. Three patients with small leak achieved leak closure more quickly. Stent migration was found in six patients, and associated ulcers occurred in five patients. We conclude that stenting is effective in the management of staple-line leaks following LSG and LDJB-SG. Stent migration and associated ulcers are common after stent placement. Early stent removal can be achieved in patients with small leaks. Copyright © 2017. Published by Elsevier Taiwan.

Treatment of air leak in polytrauma patients with blunt chest injury.

PubMed

Halat, Gabriel; Negrin, Lukas L; Chrysou, Konstantina; Hoksch, Beatrix; Schmid, Ralph A; Kocher, Gregor J

2017-09-01

Precise diagnostics and an adequate therapeutic approach are mandatory in the treatment of air leak in polytrauma patients with blunt chest trauma. The aim of this study was to evaluate the incidence, characteristics, and management of air leak following this injury pattern. Data from 110 polytrauma patients was collected retrospectively. Fifty-four patients received initial treatment by chest tube placement for pneumothorax. These patients were classified into two groups, one with severe air leak and one with minor air leak. An evaluation of injury pattern, chest wall injuries in particular, duration of air leak, reason for drainage maintenance in place, hospital length of stay, ICU stay, ventilator duration, type of treatment, and the delay to surgical intervention was performed. Whereas 4 patients showed severe air leak and were subsequently scheduled for timely surgical intervention, the remaining 50 patients only showed minor air leak. Only 7 patients with minor air leak suffered from prolonged air leak (>5days), which spontaneously resolved in all of them after a mean duration of 7.7days (range 6-12days). Absence of a prolonged air leak resulted in a shorter length of stay and a shorter duration of mechanical ventilation, although no statistical significance was observed. Early spontaneous cessation of most minor air leaks as well as early surgical intervention for severe air leak lead to very satisfactory patient outcomes with a relatively short hospital stay in our patients. We therefore advocate early surgery for lacerations of the pulmonary parenchyma resulting in severe air leak, whereas minor air leaks can usually be treated conservatively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mitigated Transfer Line Leaks that Result in Surface Pools and Spray Leaks into Pits

DOE Office of Scientific and Technical Information (OSTI.GOV)

HEY, B.E.

This analysis provides radiological and toxicological consequence calculations for postulated mitigated leaks during transfers of six waste compositions. Leaks in Cleanout Boxes equipped with supplemental covers and leaks in pits are analyzed.

Study of Residual Gas Analyser (RGA) Response towards Known Leaks

NASA Astrophysics Data System (ADS)

Pathan, Firozkhan S.; Khan, Ziauddin; Semwal, Pratibha; George, Siju; Raval, Dilip C.; Thankey, Prashant L.; Manthena, Himabindu; Yuvakiran, Paravastu; Dhanani, Kalpesh R.

2012-11-01

Helium leak testing is the most versatile form of weld qualification test for any vacuum application. Almost every ultra-high vacuum (UHV) system utilizes this technique for insuring leak tightness for the weld joints as well as demountable joints. During UHV system under operational condition with many other integrated components, in-situ developed leaks identification becomes one of the prime aspect for maintaining the health of such system and for continuing the experiments onwards. Since online utilization of leak detector (LD) has many practical limitations, residual gas analyser (RGA) can be used as a potential instrument for online leak detection. For this purpose, a co-relation for a given leak rate between Leak Detector and RGA is experimentally established. This paper describes the experimental aspect and the relationship between leak detector and RGA.

Percutaneous Vertebroplasty and Bone Cement Leakage: Clinical Experience with a New High-Viscosity Bone Cement and Delivery System for Vertebral Augmentation in Benign and Malignant Compression Fractures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anselmetti, Giovanni Carlo, E-mail: giovanni.anselmetti@ircc.i; Zoarski, Gregg; Manca, Antonio

The aim of this study was to assess the feasibility of and venous leakage reduction in percutaneous vertebroplasty (PV) using a new high-viscosity bone cement (PMMA). PV has been used effectively for pain relief in osteoporotic and malignant vertebral fractures. Cement extrusion is a common problem and can lead to complications. Sixty patients (52 female; mean age, 72.2 {+-} 7.2) suffering from osteoporosis (46), malignancy (12), and angiomas (2), divided into two groups (A and B), underwent PV on 190 vertebrae (86 dorsal, 104 lumbar). In Group A, PV with high-viscosity PMMA (Confidence, Disc-O-Tech, Israel) was used. This PMMA wasmore » injected by a proprietary delivery system, a hydraulic saline-filled screw injector. In Group B, a standard low-viscosity PMMA was used. Postprocedural CT was carried out to detect PMMA leakages and complications. Fisher's exact test and Wilcoxon rank test were used to assess significant differences (p < 0.05) in leakages and to evaluate the clinical outcome. PV was feasible, achieving good clinical outcome (p < 0.0001) without major complications. In Group A, postprocedural CT showed an asymptomatic leak in the venous structures of 8 of 98 (8.2%) treated vertebrae; a discoidal leak occurred in 6 of 98 (6.1%). In Group B, a venous leak was seen in 38 of 92 (41.3%) and a discoidal leak in 12 of 92 (13.0%). Reduction of venous leak obtained by high-viscosity PMMA was highly significant (p < 0.0001), whereas this result was not significant (p = 0.14) related to the disc. The high-viscosity PMMA system is safe and effective for clinical use, allowing a significant reduction of extravasation rate and, thus, leakage-related complications.« less

Effect of ADP on slow-twitch muscle fibres of the rat: implications for muscle fatigue

PubMed Central

Macdonald, W A; Stephenson, D G

2006-01-01

Slow-twitch mechanically skinned fibres from rat soleus muscle were bathed in solutions mimicking the myoplasmic environment but containing different [ADP] (0.1 μm to 1.0 mm). The effect of ADP on sarcoplasmic reticulum (SR) Ca2+-content was determined from the magnitude of caffeine-induced force responses, while temporal changes in SR Ca2+-content allowed determination of the effective rates of the SR Ca2+-pump and of the SR Ca2+-leak. The SR Ca2+-pump rate, estimated at pCa (−log10[Ca2+]) 7.8, was reduced by 20% as the [ADP] was increased from 0.1 to 40 μm, with no further alteration when the [ADP] was increased to 1.0 mm. The SR Ca2+-leak rate constant was not altered by increasing [ADP] from 0.1 to 40 μm, but was increased by 26% when the [ADP] was elevated to 1.0 mm. This ADP-induced SR Ca2+-leak was insensitive to ruthenium red but was abolished by 2,5-di(tert-butyl)-1,4-hydroquinone (TBQ), indicating that the leak pathway is via the SR Ca2+-pump and not the SR Ca2+-release channel. The decrease in SR Ca2+-pump rate and SR Ca2+-leak rate when [ADP] was increased led to a 40% decrease in SR Ca2+-loading capacity. Elevation of [ADP] had only minor direct effects on the contractile apparatus of slow-twitch fibres. These results suggest that ADP has only limited depressing effects on the contractility of slow-twitch muscle fibres. This is in contrast to the marked effects of ADP on force responses in fast-twitch muscle fibres and may contribute to the fatigue-resistant nature of slow-twitch muscle fibres. PMID:16556653

Evaluation of the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals through the glucose penetration model.

PubMed

Kaya, B Ureyen; Kececi, Ayşe Diljin; Belli, S

2007-12-01

To compare the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals using a recently introduced glucose penetration model. Premolars (n = 156) instrumented to an apical size of .06/40 were divided into 12 experimental and 2 control groups. The root canals were filled with either gutta-percha (groups 1-6) or Resilon (groups 7-12) core materials combined with AH Plus (groups 1, 4, 7, 0), Ketac Endo (groups 1, 5, 8, 11), or Epiphany (groups 2, 6, 9, 12), using cold lateral compaction (groups 1-3, 7-9) or System B with Obtura II (groups 4-6, 10-12). The leaked glucose concentration was measured spectrophotometrically at 1, 8, 15, 22, and 30 days. Percentage leaking of each group was also calculated. Data were recorded as mmol/L and statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests (P = .05). Throughout the experimental period Resilon/Ketac-Endo/cold lateral compaction (group 8) showed the highest mean cumulative glucose penetration (mmol/L) (17.27 +/- 10.32), whereas Resilon/AH Plus/cold lateral compaction (group 7) had the least (3.36 +/- 4.65) (P < .05). At the 30(th) day, the least leaking percentage was observed in gutta-percha, Epiphany/cold lateral compaction (group 3). Glucose penetration was affected by the obturation technique in some groups. Ketac-Endo either with gutta-percha (group 2) or Resilon (group 8) indicated significantly less glucose penetration in warm technique, whereas gutta-percha/Epiphany (group 3) had significantly less glucose penetration in cold technique (P < .05). All material/technique combinations allowed glucose penetration. Gutta-percha/AH Plus combinations allowed similar patterns of glucose penetration to Resilon/Epiphany combinations.

Predictive factors for outcomes of patients undergoing endoscopic therapy for bile leak after hepatobiliary surgery.

PubMed

Yabe, Shuntaro; Kato, Hironari; Mizukawa, Sho; Akimoto, Yutaka; Uchida, Daisuke; Seki, Hiroyuki; Tomoda, Takeshi; Matsumoto, Kazuyuki; Yamamoto, Naoki; Horiguchi, Shigeru; Tsutsumi, Koichiro; Okada, Hiroyuki

2017-05-01

Endoscopic procedures are used as first-line treatment for bile leak after hepatobiliary surgery. Advances have been made in endoscopic techniques and devices, but few reports have described the effectiveness of endoscopic procedures and the management principles based on severity of bile leak. We evaluated the effectiveness of an endoscopic procedure for the treatment of bile leak after hepatobiliary surgery. Fifty-eight patients underwent an endoscopic procedure for suspected bile leak after hepatobiliary surgery; the presence of bile leak on endoscopic retrograde cholangiopancreatography (ERCP) was evaluated retrospectively. Two groups were created based on bile leak severity at ERCP. We defined success as follows: technical, successful placement of the plastic stent at the intended bile duct; clinical, improvement in symptoms of bile leak; and eventual, disappearance of bile leak at ERCP. We evaluated several factors that influenced the success of the endoscopic procedure and the differences between bile leak severity. Success rates were as follows: technical, 90%; clinical, 79%; and eventual, 71%. Median interval between first endoscopic procedure and achievement of eventual success was 135 days (IQR, 86-257 days). Bile leak severity was the only independent factor associated with eventual success (P = 0.01). Endoscopic therapy is safe and effective for postoperative bile leak. Bile leak severity is the most important factor influencing successful endoscopic therapy. © 2016 Japan Gastroenterological Endoscopy Society.

Determining and understanding the control of flux. An illustration in submitochondrial particles of how to validate schemes of metabolic control.

PubMed

Moreno-Sánchez, R; Bravo, C; Westerhoff, H V

1999-09-01

Two complementary methods were used to determine how the rate of respiration and that of ATP hydrolysis were controlled in rat liver submitochondrial particles. In the first, 'direct control analysis' method, respiration was titrated with malonate, antimycin or cyanide at 20, 30 and 37 degrees C, to determine the flux control exerted by succinate dehydrogenase, cytochrome bc1 complex and cytochrome c oxidase, respectively. Together, the three respiratory complexes only controlled the flux by about 50%, leaving the other 50% of flux control to the H+ leak. In the second, 'elasticity based' method, the elasticity coefficients of the respiratory chain or the H+-ATPase and the H+ leak towards the H+ gradient were determined. Then, the flux control coefficients were calculated using the connectivity and summation laws of metabolic control theory. The correspondence between the flux control coefficients determined in the two ways validated the two methods. This allowed us to use the second method to analyse what was the kinetic origin of the observed distribution of control. Control of ATP hydrolysis by the ATPase decreased with increasing ATPase activity; hence, the control exerted by the H+ leak increased with increasing ATPase activity, due to a diminishing elasticity towards the H+ gradient. Reverse electron transport was mainly controlled by the ATPase; the sum of flux control coefficients of succinate dehydrogenase, NADH-CoQ oxidoreductase, and H+-ATPase yielded a value greater than one, indicating that the H+ leak exerted a significant negative control on this pathway.

Ultrasonic Phased Array Assessment of the Interference Fit and Leak Path of the North Anna Unit 2 Control Rod Drive Mechanism Nozzle 63 with Destructive Validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crawford, Susan L.; Cinson, Anthony D.; MacFarlan, Paul J.

2012-08-01

The objective of this investigation was to evaluate the efficacy of ultrasonic testing (UT) for primary water leak path assessments of reactor pressure vessel (RPV) upper head penetrations. Operating reactors have experienced leakage when stress corrosion cracking of nickel-based alloy penetrations allowed primary water into the annulus of the interference fit between the penetration and the low-alloy steel RPV head. In this investigation, UT leak path data were acquired for an Alloy 600 control rod drive mechanism nozzle penetration, referred to as Nozzle 63, which was removed from the North Anna Unit 2 reactor when the RPV head was replacedmore » in 2002. In-service inspection prior to the head replacement indicated that Nozzle 63 had a probable leakage path through the interference fit region. Nozzle 63 was examined using a phased-array UT probe with a 5.0-MHz, eight-element annular array. Immersion data were acquired from the nozzle inner diameter surface. The UT data were interpreted by comparing to responses measured on a mockup penetration with known features. Following acquisition of the UT data, Nozzle 63 was destructively examined to determine if the features identified in the UT examination, including leakage paths and crystalline boric acid deposits, could be visually confirmed. Additional measurements of boric acid deposit thickness and low-alloy steel wastage were made to assess how these factors affect the UT response. The implications of these findings for interpreting UT leak path data are described.« less

INNOVATIVE ACOUSTIC SENSOR TECHNOLOGIES FOR LEAK DETECTION IN CHALLENGING PIPE TYPES

DTIC Science & Technology

2016-12-30

through focused acoustic surveys that are typically conducted at the correlated location prior to marking the leak location. All three technologies were...shift” survey with cross- correlation Echologics LeakFinderRTT M Field survey of leak signatures. Recommended every 3-5 years Contractor...cross- correlation features to detect and pinpoint leaks in challenging pipe types, as well as metallic pipes. 15. SUBJECT TERMS Leak detection

40 CFR 265.196 - Response to leaks or spills and disposition of leaking or unfit-for-use tank systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Response to leaks or spills and... leaks or spills and disposition of leaking or unfit-for-use tank systems. A tank system or secondary containment system from which there has been a leak or spill, or which is un-fit for use, must be removed from...

40 CFR 63.1023 - Instrument and sensory monitoring for leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... leaks. 63.1023 Section 63.1023 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 2 Standards § 63.1023 Instrument and sensory monitoring for leaks. (a) Monitoring for leaks. The owner or operator of a regulated...

40 CFR 65.104 - Instrument and sensory monitoring for leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... leaks. 65.104 Section 65.104 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Equipment Leaks § 65.104 Instrument and sensory monitoring for leaks. (a) Monitoring for leaks. The owner or operator of a regulated source subject to this...

40 CFR 63.1004 - Instrument and sensory monitoring for leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... leaks. 63.1004 Section 63.1004 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 1 § 63.1004 Instrument and sensory monitoring for leaks. (a) Monitoring for leaks. The owner or operator of a regulated source subject to this...

Leak detection by mass balance effective for Norman Wells line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liou, J.C.P.

Mass-balance calculations for leak detection have been shown as effective as a leading software system, in a comparison based on a major Canadian crude-oil pipeline. The calculations and NovaCorp`s Leakstop software each detected 4% (approximately) or greater leaks on Interprovincial Pipe Line (IPL) Inc.`s Norman Wells pipeline. Insufficient data exist to assess performances of the two methods for leaks smaller than 4%. Pipeline leak detection using such software-based systems are common. Their effectiveness is measured by how small and how quickly a leak can be detected. Algorithms used and measurement uncertainties determine leak detectability.

Water conservation study. Badger Army Ammunition Plant, Baraboo, Wisconsin. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-05-01

The purpose of this water conservation study is to identify projects which result in energy maintenance and cost savings in the process water distribution system at Badger Army Ammunition Plant (BAAP) in Baraboo, Wisconsin. A leak detection survey was performed on all process water piping with a diameter of 6 inches or greater. The leak detection analysis was performed using a combination of listening devices and preamplified-transducer systems to identify the majority of leak locations. When the location of the leak could not be readily identified using these methods, a leak correlator was used. The leak correlator determines leak locationmore » based on the time it takes for sound to travel from the leak to a waterline connection point.« less

Rapid, Vehicle-Based Identification of Location and Magnitude of Urban Natural Gas Pipeline Leaks.

PubMed

von Fischer, Joseph C; Cooley, Daniel; Chamberlain, Sam; Gaylord, Adam; Griebenow, Claire J; Hamburg, Steven P; Salo, Jessica; Schumacher, Russ; Theobald, David; Ham, Jay

2017-04-04

Information about the location and magnitudes of natural gas (NG) leaks from urban distribution pipelines is important for minimizing greenhouse gas emissions and optimizing investment in pipeline management. To enable rapid collection of such data, we developed a relatively simple method using high-precision methane analyzers in Google Street View cars. Our data indicate that this automated leak survey system can document patterns in leak location and magnitude within and among cities, even without wind data. We found that urban areas with prevalent corrosion-prone distribution lines (Boston, MA, Staten Island, NY, and Syracuse, NY), leaked approximately 25-fold more methane than cities with more modern pipeline materials (Burlington, VT, and Indianapolis, IN). Although this mobile monitoring method produces conservative estimates of leak rates and leak counts, it can still help prioritize both leak repairs and replacement of leak-prone sections of distribution lines, thus minimizing methane emissions over short and long terms.

Improved techniques reduce face mask leak during simulated neonatal resuscitation: study 2.

PubMed

Wood, Fiona E; Morley, Colin J; Dawson, Jennifer A; Kamlin, C Omar F; Owen, Louise S; Donath, Susan; Davis, Peter G

2008-05-01

Techniques of positioning and holding neonatal face masks vary. Studies have shown that leak at the face mask is common and often substantial irrespective of operator experience. (1) To identify a technique for face mask placement and hold which will minimise mask leak. (2) To investigate the effect of written instruction and demonstration of the identified technique on mask leak for two round face masks. Three experienced neonatologists compared methods of placing and holding face masks to minimise the leak for Fisher & Paykel 60 mm and Laerdal size 0/1 masks. 50 clinical staff gave positive pressure ventilation to a modified manikin designed to measure leak at the face mask. They were provided with written instructions on how to position and hold each mask and then received a demonstration. Face mask leak was measured after each teaching intervention. A technique of positioning and holding the face masks was identified which minimised leak. The mean (SD) mask leaks before instruction, after instruction and after demonstration were 55% (31), 49% (30), 33% (26) for the Laerdal mask and 57% (25), 47% (28), 32% (30) for the Fisher & Paykel mask. There was no significant difference in mask leak between the two masks. Written instruction alone reduced leak by 8.8% (CI 1.4% to 16.2%) for either mask; when combined with a demonstration mask leak was reduced by 24.1% (CI 16.4% to 31.8%). Written instruction and demonstration of the identified optimal technique resulted in significantly reduced face mask leak.

Mitochondrial proton and electron leaks.

PubMed

Jastroch, Martin; Divakaruni, Ajit S; Mookerjee, Shona; Treberg, Jason R; Brand, Martin D

2010-01-01

Mitochondrial proton and electron leak have a major impact on mitochondrial coupling efficiency and production of reactive oxygen species. In the first part of this chapter, we address the molecular nature of the basal and inducible proton leak pathways, and their physiological importance. The basal leak is unregulated, and a major proportion can be attributed to mitochondrial anion carriers, whereas the proton leak through the lipid bilayer appears to be minor. The basal proton leak is cell-type specific and correlates with metabolic rate. The inducible leak through the ANT (adenine nucleotide translocase) and UCPs (uncoupling proteins) can be activated by fatty acids, superoxide or lipid peroxidation products. The physiological role of inducible leak through UCP1 in mammalian brown adipose tissue is heat production, whereas the roles of non-mammalian UCP1 and its paralogous proteins, in particular UCP2 and UCP3, are not yet resolved. The second part of the chapter focuses on the electron leak that occurs in the mitochondrial electron transport chain. Exit of electrons prior to the reduction of oxygen to water at cytochrome c oxidase causes superoxide production. As the mechanisms of electron leak are crucial to understanding their physiological relevance, we summarize the mechanisms and topology of electron leak from complexes I and III in studies using isolated mitochondria. We also highlight recent progress and challenges of assessing electron leak in the living cell. Finally, we emphasize the importance of proton and electron leak as therapeutic targets in body mass regulation and insulin secretion.

Fugitive methane emissions from natural, urban, agricultural, and energy-production landscapes of eastern Australia

NASA Astrophysics Data System (ADS)

Kelly, Bryce F. J.; Iverach, Charlotte P.; Lowry, Dave; Fisher, Rebecca E.; France, James L.; Nisbet, Euan G.

2015-04-01

Modern cavity ringdown spectroscopy systems (CRDS) enable the continuous measurement of methane concentration. This allows for improved quantification of greenhouse gas emissions associated with various natural and human landscapes. We present a subset of over 4000 km of continuous methane surveying along the east coast of Australia, made using a Picarro G2301 CRDS, deployed in a utility vehicle with an air inlet above the roof at 2.2 mAGL. Measurements were made every 5 seconds to a precision of <0.5 ppb for CH4. These surveys were undertaken during dry daytime hours and all measurements were moisture corrected. We compare the concentration of methane in the near surface atmosphere adjacent to open-cut coal mines, unconventional gas developments (coal seam gas; CSG), and leaks detected in cities and country towns. In areas of dryland crops the median methane concentration was 1.78 ppm, while in the irrigation districts located on vertisol soils the concentration was as low as 1.76 ppm, which may indicate that these soils are a sink for methane. In the Hunter Valley, New South Wales, open-cut coal mining district we mapped a continuous 50 km interval where the concentration of methane exceeded 1.80 ppm. The median concentration in this interval was 2.02 ppm. Peak readings were beyond the range of the reliable measurement (in excess of 3.00 ppm). This extended plume is an amalgamation of plumes from 17 major pits 1 to 10 km in length. Adjacent to CSG developments in the Surat Basin, southeast Queensland, only small anomalies were detected near the well-heads. Throughout the vast majority of the gas fields the concentration of methane was below 1.80 ppm. The largest source of fugitive methane associated with CSG was off-gassing methane from the co-produced water holding ponds. At one location the down wind plume had a cross section of approximately 1 km where the concentration of methane was above 1.80 ppm. The median concentration within this section was 1.82 ppm, with a peak reading of 2.11 ppm. The ambient air methane concentration was always higher in urban environments compared to the surrounding countryside. Along one major road in Sydney we mapped an interval that extended for 6 km where the concentration was greater than 1.80 ppm. The median concentration in this interval was 1.90 ppm, with a peak reading of 1.97 ppm. This high reading in an urban setting is most likely due to leaks from the domestic gas distribution system. Methane leaks were detected in all country towns. Our measurements show that at the point of resource extraction the methane emission footprint of CSG is smaller than that of open-cut coal mining. However, leaking gas from urban centers must be added to the fugitive emissions of CSG to calculate the total fugitive emission footprint of CSG, which may therefore not be as low as claimed in the national greenhouse gas accounts. Our results highlight the need for additional continuous monitoring of methane emissions from all sectors, and for the full life-cycle of energy resources to be considered.

Leaching behaviour of different scrap materials at recovery and recycling companies: full-, pilot- and lab-scale investigation.

PubMed

Blondeel, E; Chys, M; Depuydt, V; Folens, K; Du Laing, G; Verliefde, A; Van Hulle, S W H

2014-12-01

Scrap material recovery and recycling companies are confronted with waste water that has a highly fluctuating flow rate and composition. Common pollutants, such as COD, nutrients and suspended solids, potentially toxic metals, polyaromatic hydrocarbons and poly chlorinated biphenyls can exceed the discharge limits. An analysis of the leaching behaviour of different scrap materials and scrap yard sweepings was performed at full-scale, pilot-scale and lab-scale in order to find possible preventive solutions for this waste water problem. The results of these leaching tests (with concentrations that frequently exceeded the Flemish discharge limits) showed the importance of regular sweeping campaigns at the company, leak proof or covered storage of specific scrap materials and oil/water separation on particular leachates. The particulate versus dissolved fraction was also studied for the pollutants. For example, up to 98% of the polyaromatic hydrocarbons, poly chlorinated biphenyls and some metals were in the particulate form. This confirms the (potential) applicability of sedimentation and filtration techniques for the treatment of the majority of the leachates, and as such the rainwater run-off as a whole. Copyright © 2014 Elsevier Ltd. All rights reserved.

Incidence, risk factors and clinical implications of chyle leak after pancreatic surgery.

PubMed

Strobel, O; Brangs, S; Hinz, U; Pausch, T; Hüttner, F J; Diener, M K; Schneider, L; Hackert, T; Büchler, M W

2017-01-01

Chyle leak is a well known but poorly characterized complication after pancreatic surgery. Available data on incidence, risk factors and clinical significance of chyle leak are highly heterogeneous. For this cohort study all patients who underwent pancreatic surgery between January 2008 and December 2012 were identified from a prospective database. Chyle leak was defined as any drainage output with triglyceride content of 110 mg/dl or more. Risk factors for chyle leak were assessed by univariable and multivariable analyses. The clinical relevance of chyle leak was evaluated using hospital stay and resolution by 14 days for short-term outcome and overall survival for long-term outcome. Chyle leak developed in 346 (10·4 per cent) of 3324 patients. Pre-existing diabetes, resection for malignancy, distal pancreatectomy, duration of surgery 180 min or longer, and concomitant pancreatic fistula or abscess were independent risk factors for chyle leak. Both isolated chyle leak and coincidental chyle leak (with other intra-abdominal complications) were associated with prolonged hospital stay. Some 178 (87·7 per cent) of 203 isolated chyle leaks and 90 (70·3 per cent) of 128 coincidental chyle leaks resolved with conservative management within 14 days. Initial and maximum drainage volumes were associated with duration of hospital stay and success of therapy by 14 days. Impact on survival was restricted to chyle leaks that persisted at 14 days in patients with cancer undergoing palliative surgery. Chyle leak is a relevant complication, with an incidence of more than 10 per cent after pancreatic surgery, and has a major impact on hospital stay. Drainage volume is associated with hospital stay and success of therapy. © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd.

Routine intraoperative leak testing for sleeve gastrectomy: is the leak test full of hot air?

PubMed

Bingham, Jason; Lallemand, Michael; Barron, Morgan; Kuckelman, John; Carter, Preston; Blair, Kelly; Martin, Matthew

2016-05-01

Staple line leak after sleeve gastrectomy (SG) is a rare but dreaded complication with a reported incidence of 0% to 8%. Many surgeons routinely test the staple line with an intraoperative leak test (IOLT), but there is little evidence to validate this practice. In fact, there is a theoretical concern that the leak test may weaken the staple line and increase the risk of a postop leak. Retrospective review of all SGs performed over a 7-year period was conducted. Cases were grouped by whether an IOLT was performed, and compared for the incidence of postop staple line leaks. The ability of the IOLT for identifying a staple line defect and for predicting a postoperative leak was analyzed. Five hundred forty-two SGs were performed between 2007 and 2014. Thirteen patients (2.4%) developed a postop staple line leak. The majority of patients (n = 494, 91%) received an IOLT, including all 13 patients (100%) who developed a subsequent clinical leak. There were no (0%) positive IOLTs and no additional interventions were performed based on the IOLT. The IOLT sensitivity and positive predictive value were both 0%. There was a trend, although not significant, to increase leak rates when a routine IOLT was performed vs no routine IOLT (2.6% vs 0%, P = .6). The performance of routine IOLT after SG provided no actionable information, and was negative in all patients who developed a postoperative leak. The routine use of an IOLT did not reduce the incidence of postop leak, and in fact was associated with a higher leak rate after SG. Published by Elsevier Inc.

Pressure Monitoring to Detect Fault Rupture Due to CO 2 Injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keating, Elizabeth; Dempsey, David; Pawar, Rajesh

The capacity for fault systems to be reactivated by fluid injection is well-known. In the context of CO 2 sequestration, however, the consequence of reactivated faults with respect to leakage and monitoring is poorly understood. Using multi-phase fluid flow simulations, this study addresses key questions concerning the likelihood of ruptures, the timing of consequent upward leakage of CO 2, and the effectiveness of pressure monitoring in the reservoir and overlying zones for rupture detection. A range of injection scenarios was simulated using random sampling of uncertain parameters. These include the assumed distance between the injector and the vulnerable fault zone,more » the critical overpressure required for the fault to rupture, reservoir permeability, and the CO 2 injection rate. We assumed a conservative scenario, in which if at any time during the five-year simulations the critical fault overpressure is exceeded, the fault permeability is assumed to instantaneously increase. For the purposes of conservatism we assume that CO 2 injection continues ‘blindly’ after fault rupture. We show that, despite this assumption, in most cases the CO 2 plume does not reach the base of the ruptured fault after 5 years. As a result, one possible implication of this result is that leak mitigation strategies such as pressure management have a reasonable chance of preventing a CO 2 leak.« less

Pressure Monitoring to Detect Fault Rupture Due to CO 2 Injection

DOE PAGES

Keating, Elizabeth; Dempsey, David; Pawar, Rajesh

2017-08-18

The capacity for fault systems to be reactivated by fluid injection is well-known. In the context of CO 2 sequestration, however, the consequence of reactivated faults with respect to leakage and monitoring is poorly understood. Using multi-phase fluid flow simulations, this study addresses key questions concerning the likelihood of ruptures, the timing of consequent upward leakage of CO 2, and the effectiveness of pressure monitoring in the reservoir and overlying zones for rupture detection. A range of injection scenarios was simulated using random sampling of uncertain parameters. These include the assumed distance between the injector and the vulnerable fault zone,more » the critical overpressure required for the fault to rupture, reservoir permeability, and the CO 2 injection rate. We assumed a conservative scenario, in which if at any time during the five-year simulations the critical fault overpressure is exceeded, the fault permeability is assumed to instantaneously increase. For the purposes of conservatism we assume that CO 2 injection continues ‘blindly’ after fault rupture. We show that, despite this assumption, in most cases the CO 2 plume does not reach the base of the ruptured fault after 5 years. As a result, one possible implication of this result is that leak mitigation strategies such as pressure management have a reasonable chance of preventing a CO 2 leak.« less

New technique to prevent prolonged air leak: use of 'Tachosuture' technique.

PubMed

Nishida, Tatsuya; Mikami, Iwao; Fujii, Yoshitaka

2017-02-01

Prolonged air leak (defined as air leak >7 days), caused by pulmonary resection or alveolar-pleural fistula, increases postoperative morbidity, prolongs hospital stay and increases healthcare costs. We describe a new technique ('Tachosuture' technique) to prevent prolonged air leak. The key point of this new technique is that air leak is classified into three types and an absorbable suture is added to a TachoSil ® patch in each type to prevent detachment from the lung parenchyma. Between August 2013 and March 2016, 40 patients underwent thoracoscopic surgery using 'Tachosuture' technique. Postoperative air leak always stopped within 3 days (95% confidence interval for the absence of prolonged air leak: 92.5-100%). It is considered that this simple technique is useful to prevent prolonged air leak.

Drain Tube-Induced Jejunal Penetration Masquerading as Bile Leak following Whipple's Operation.

PubMed

Bae, Sang Ho; Lee, Tae Hoon; Lee, Sae Hwan; Lee, Suck-Ho; Park, Sang-Heum; Kim, Sun-Joo; Kim, Chang Ho

2011-05-01

A 70-year-old man had undergone pancreaticoduodenectomy due to a distal common bile duct malignancy. After the operation, serous fluid discharge decreased from two drain tubes in the retroperitoneum. Over four weeks, the appearance of the serous fluid changed to a greenish bile color and the patient persistently drained over 300 ml/day. Viewed as bile leak at the choledochojejunostomy, treatment called for endoscopic diagnosis and therapy. Cap-fitted forward-viewing endoscopy demonstrated that the distal tip of a pancreatic drain catheter inserted at the pancreaticojejunostomy site had penetrated the opposite jejunum wall. One of the drain tubes primarily placed in the retroperitoneum had also penetrated the jejunum wall, with the distal tip positioned near the choledochojejunostomy site. No leak of contrast appeared beyond the jejunum or anastomosis site. Following repositioning of a penetrating catheter of the pancreaticojejunostomy, four days later, the patient underwent removal of two drain tubes without additional complications. In conclusion, the distal tip of the catheter, placed to drain pancreatic juice, penetrated the jejunum wall and may have caused localized perijejunal inflammation. The other drain tube, placed in the retroperitoneal space, might then have penetrated the inflamed wall of the jejunum, allowing persistent bile drainage via the drain tube. The results masqueraded as bile leakage following pancreaticoduodenectomy.

Initiation and propagation of a PKN hydraulic fracture in permeable rock: Toughness dominated regime

NASA Astrophysics Data System (ADS)

Sarvaramini, E.; Garagash, D.

2011-12-01

The present work investigates the injection of a low-viscosity fluid into a pre-existing fracture with constrained height (PKN), as in waterflooding or supercritical CO2 injection. Contrary to conventional hydraulic fracturing, where 'cake build up' limits diffusion to a small zone, the low viscosity fluid allows for diffusion over a wider range of scales. Over large injection times the pattern becomes 2 or 3-D, necessitating a full-space diffusion modeling. In addition, the dissipation of energy associated with fracturing of rock dominates the energy needed for the low-viscosity fluid flow into the propagating crack. As a result, the fracture toughness is important in evaluating both the initiation and the ensuing propagation of these fractures. Classical PKN hydraulic fracturing model, amended to account for full-space leak-off and the toughness [Garagash, unpublished 2009], is used to evaluate the pressure history and fluid leak-off volume during the injection of low viscosity fluid into a pre-existing and initially stationary. In order to find the pressure history, the stationary crack is first subject to a step pressure increase. The response of the porous medium to the step pressure increase in terms of fluid leak-off volume provides the fundamental solution, which then can be used to find the transient pressurization using Duhamel theorem [Detournay & Cheng, IJSS 1991]. For the step pressure increase an integral equation technique is used to find the leak-off rate history. For small time the solution must converge to short time asymptote, which corresponds to 1-D diffusion pattern. However, as the diffusion length in the zone around the fracture increases the assumption of a 1-D pattern is no longer valid and the diffusion follows a 2-D pattern. The solution to the corresponding integral equation gives the leak-off rate history, which is used to find the cumulative leak-off volume. The transient pressurization solution is obtained using global conservation of fluid injected into the fracture. With increasing pressure in the fracture due to the fluid injection, the energy release rate eventually becomes equal to the toughness and fracture propagates. The evolution of the fracture length is established using the method similar to the one employed for the stationary crack.

Effects of N-acetylcysteine and terbutaline treatment on hemodynamics and regional albumin extravasation in porcine septic shock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groeneveld, A.B.; den Hollander, W.; Straub, J.

We studied the therapeutic effects of continuously infused N-acetylcysteine, an O2 radical scavenger (N, n = 6), and terbutaline, a beta 2-agonist (T, n = 6), versus dextrose (controls C, N = 6) on hemodynamics and regional albumin extravasation in porcine septic shock. After instrumentation, injection of 99mTc-labeled red blood cells, and baseline measurements, pigs received a 90 min infusion of 11 +/- 9 X 10(8).kg-1 live Escherichia coli bacteria. Thereafter, therapy was started, and 131I human serum albumin was injected. Images were obtained hourly using a gamma camera and a computer until 5 hours after baseline. Regions of interestmore » were drawn in the 99mTc images, yielding regional 131I/99mTc radioactivity ratios, with blood samples as reference. From these ratios, an albumin leak index, a rate constant of transvascular albumin transport, was calculated. Control pigs developed pulmonary hypertension, arterial hypotension, hemoconcentration, and lactic acidemia. In spite of tachycardia and unchanged filling pressures, cardiac output fell. In arterial blood, white cell count, PO2, albumin level, and colloid osmotic pressure fell. The albumin leak index (X10(-3).min-1) measured 1.56 +/- 0.59 over the lungs and 2.87 +/- 1.19 over the abdomen in C, confirming previously found increased albumin flux in both lung and abdomen, the latter exceeding the former. Neither N nor T significantly affected hemodynamic and biochemical changes. The drugs neither decreased the regional albumin leak index nor attenuated the formation of albumin-rich ascites found at autopsy. However, the lung albumin index obtained at autopsy was significantly reduced with N (P less than .01 vs. C), at similar gravimetrically determined extravascular lung water (EVLW). EVLW positively correlated with pulmonary albumin extravasation in C and T but not in N.« less

Premature rupture of membranes

MedlinePlus

... is fluid leaking from the vagina. It may leak slowly, or it may gush out. Some of ... the membranes break. The membranes may continue to leak. Sometimes when fluid leaks out slowly, women mistake ...

40 CFR 86.1337-96 - Engine dynamometer test run.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., dynamometer, and sampling system. (iii) Change filters, etc., and leak check as necessary. For a single... sample is lost. A separate leak check is needed. A leak check of a filter assembly that has only one seal ring in contact with the filter media will not detect a leak when tested under vacuum. A pressure leak...

40 CFR 86.1337-96 - Engine dynamometer test run.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., dynamometer, and sampling system. (iii) Change filters, etc., and leak check as necessary. For a single... sample is lost. A separate leak check is needed. A leak check of a filter assembly that has only one seal ring in contact with the filter media will not detect a leak when tested under vacuum. A pressure leak...

40 CFR 86.1337-96 - Engine dynamometer test run.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., dynamometer, and sampling system. (iii) Change filters, etc., and leak check as necessary. For a single... sample is lost. A separate leak check is needed. A leak check of a filter assembly that has only one seal ring in contact with the filter media will not detect a leak when tested under vacuum. A pressure leak...

40 CFR 86.1337-96 - Engine dynamometer test run.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., dynamometer, and sampling system. (iii) Change filters, etc., and leak check as necessary. For a single... sample is lost. A separate leak check is needed. A leak check of a filter assembly that has only one seal ring in contact with the filter media will not detect a leak when tested under vacuum. A pressure leak...

Endotracheal tube leak pressure and tracheal lumen size in swine.

PubMed

Finholt, D A; Audenaert, S M; Stirt, J A; Marcella, K L; Frierson, H F; Suddarth, L T; Raphaely, R C

1986-06-01

Endotracheal tube "leak" is often estimated in children to judge the fit of uncuffed endotracheal tubes within the trachea. Twenty-five swine were intubated with uncuffed tracheal tubes to determine whether a more sensitive measurement of leaks could be devised and whether leak pressure estimates fit between tracheal tube and trachea. We compared leak pressure measurement using a stethoscope and aneroid manometer with a technique using a microphone, pressure transducer, and recorder, and found no differences between the two methods. The tracheas were then removed and slides prepared of tracheal cross-sectional specimens. Regression analysis revealed a linear relationship between tracheal lumen size and tracheal tube size for both low leak pressure (y = -0.4 + 0.79x, r = 0.88, P less than 0.05) and high leak pressure (y = -2.9 + 0.71x, r = 0.92, P less than 0.05) groups. We conclude that leak testing with a stethoscope and aneroid manometer is sensitive and accurate, and that tracheal tube leak pressure accurately portrays fit between tube and trachea.

Leak checker data logging system

DOEpatents

Gannon, J.C.; Payne, J.J.

1996-09-03

A portable, high speed, computer-based data logging system for field testing systems or components located some distance apart employs a plurality of spaced mass spectrometers and is particularly adapted for monitoring the vacuum integrity of a long string of a superconducting magnets such as used in high energy particle accelerators. The system provides precise tracking of a gas such as helium through the magnet string when the helium is released into the vacuum by monitoring the spaced mass spectrometers allowing for control, display and storage of various parameters involved with leak detection and localization. A system user can observe the flow of helium through the magnet string on a real-time basis hour the exact moment of opening of the helium input valve. Graph reading can be normalized to compensate for magnet sections that deplete vacuum faster than other sections between testing to permit repetitive testing of vacuum integrity in reduced time. 18 figs.

Leak checker data logging system

DOEpatents

Gannon, Jeffrey C.; Payne, John J.

1996-01-01

A portable, high speed, computer-based data logging system for field testing systems or components located some distance apart employs a plurality of spaced mass spectrometers and is particularly adapted for monitoring the vacuum integrity of a long string of a superconducting magnets such as used in high energy particle accelerators. The system provides precise tracking of a gas such as helium through the magnet string when the helium is released into the vacuum by monitoring the spaced mass spectrometers allowing for control, display and storage of various parameters involved with leak detection and localization. A system user can observe the flow of helium through the magnet string on a real-time basis hour the exact moment of opening of the helium input valve. Graph reading can be normalized to compensate for magnet sections that deplete vacuum faster than other sections between testing to permit repetitive testing of vacuum integrity in reduced time.

Likelihood of Brine and CO 2 Leak Detection using Magnetotellurics and Electrical Resistivity Tomography Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X.; Buscheck, T. A.; Mansoor, K.

The US DOE National Risk Assessment Partnership (NRAP), funded through the Office of Fossil Energy and NETL, is developing methods to evaluate the effectiveness of monitoring techniques to detect brine and CO 2 leakage from legacy wells into underground sources of drinking water (USDW) overlying a CO 2 storage reservoir. As part of the NRAP Strategic Monitoring group, we have generated 140 simulations of aquifer impact data based on the Kimberlina site in California’s southern San Joaquin Basin, Kimberlina Rev. 1.1. CO 2 buoyancy allows some of the stored CO 2 to reach shallower permeable zones and is detectable withmore » surface geophysical sensors. We are using this simulated data set to evaluate effectiveness of electrical resistivity tomography (ERT) and magnetotellurics (MT) for leak detection. The evaluation of additional monitoring methods such as pressure, seismic and gravity is underway through a multi-lab collaboration.« less

Treatment of sleep-disordered breathing with positive airway pressure devices: technology update.

PubMed

Johnson, Karin Gardner; Johnson, Douglas Clark

2015-01-01

Many types of positive airway pressure (PAP) devices are used to treat sleep-disordered breathing including obstructive sleep apnea, central sleep apnea, and sleep-related hypoventilation. These include continuous PAP, autoadjusting CPAP, bilevel PAP, adaptive servoventilation, and volume-assured pressure support. Noninvasive PAP has significant leak by design, which these devices adjust for in different manners. Algorithms to provide pressure, detect events, and respond to events vary greatly between the types of devices, and vary among the same category between companies and different models by the same company. Many devices include features designed to improve effectiveness and patient comfort. Data collection systems can track compliance, pressure, leak, and efficacy. Understanding how each device works allows the clinician to better select the best device and settings for a given patient. This paper reviews PAP devices, including their algorithms, settings, and features.

Steam generator tubes integrity: In-service-inspection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Comby, R.J.

1997-02-01

The author`s approach to tube integrity is in terms of looking for flaws in tubes. The basis for this approach is that no simple rules can be fixed to adopt a universal inspection methodology because of various concepts related to experience, leak acceptance, leak before break approach, etc. Flaw specific management is probably the most reliable approach as a compromise between safety, availability and economic issues. In that case, NDE capabilities have to be in accordance with information required by structural integrity demonstration. The author discusses the types of probes which can be used to search for flaws in additionmore » to the types of flaws which are being sought, with examples of specific analysis experiences. The author also discusses the issue of a reporting level as it relates to avoiding false calls, classifying faults, and allowing for automation in analysis.« less

The Use of Spontaneous Raman Scattering for Hydrogen Leak Detection

NASA Technical Reports Server (NTRS)

Degroot, Wim A.

1994-01-01

A fiber optic probe has been built and demonstrated that utilizes back scattered spontaneous Raman spectroscopy to detect and identify gaseous species. The small probe, coupled to the laser and data acquisition equipment with optical fibers, has applications in gaseous leak detection and process monitoring. The probe design and data acquisition system are described. Raman scattering theory has been reviewed and the results of intensity calculations of hydrogen and nitrogen Raman scattering are given. Because the device is in its developmental stage, only preliminary experimental results are presented here. Intensity scans across the rotational-vibrational Raman lines of nitrogen and hydrogen are presented. Nitrogen at a partial pressure of 0.077 MPa was detected. Hydrogen at a partial pressure of 2 kPa approached the lower limit of detectability with the present apparatus. Potential instrument improvements that would allow more sensitive and rapid hydrogen detection are identified.

The Demonstration of a Robotic External Leak Locator on the International Space Station

NASA Technical Reports Server (NTRS)

Naids, Adam; Rossetti, Dino; Bond, Tim; Johnson, Brien; Huang, Alvin; Deal, Alexandra; Fox, Katie; Heiser, Michael; Hartman, William; Mikatarian, Ronald

2017-01-01

The International Space Station (ISS) and all currently conceivable future manned spacecraft are susceptible to mission impacts due to fluid/gas leaks to the exterior environment. For example, there is a well-known risk of ammonia leaks from the ISS External Thermal Control System loops and currently no method to locate them. It was, therefore, critical to develop a method for detecting and locating leaks to preserve vehicle health. The Robotic External Leak Locator (RELL) was developed and deployed to the ISS to provide this capability. An on-orbit validation and demonstration was successfully completed in December 2016 and leak locating operations occurred in February 2017. This paper discusses the results of those exercises including measurements of the environment around ISS, detection of the small ammonia leak and implementation of leak locating methodologies.

40 CFR 63.1184 - What do I need to know about the design specifications, installation, and operation of a bag leak...

Code of Federal Regulations, 2010 CFR

2010-07-01

... design specifications, installation, and operation of a bag leak detection system? 63.1184 Section 63... bag leak detection system? A bag leak detection system must meet the following requirements: (a) The bag leak detection system must be certified by the manufacturer to be capable of detecting PM...

Detection of Leaks in Water Distribution System using Non-Destructive Techniques

NASA Astrophysics Data System (ADS)

Aslam, H.; Kaur, M.; Sasi, S.; Mortula, Md M.; Yehia, S.; Ali, T.

2018-05-01

Water is scarce and needs to be conserved. A considerable amount of water which flows in the water distribution systems was found to be lost due to pipe leaks. Consequently, innovations in methods of pipe leakage detections for early recognition and repair of these leaks is vital to ensure minimum wastage of water in distribution systems. A major component of detection of pipe leaks is the ability to accurately locate the leak location in pipes through minimum invasion. Therefore, this paper studies the leak detection abilities of the three NDT’s: Ground Penetration Radar (GPR) and spectrometer and aims at determining whether these instruments are effective in identifying the leak. An experimental setup was constructed to simulate the underground conditions of water distribution systems. After analysing the experimental data, it was concluded that both the GPR and the spectrometer were effective in detecting leaks in the pipes. However, the results obtained from the spectrometer were not very differentiating in terms of observing the leaks in comparison to the results obtained from the GPR. In addition to this, it was concluded that both instruments could not be used if the water from the leaks had reached on the surface, resulting in surface ponding.

Percutaneous management of postoperative bile leaks with an ethylene vinyl alcohol copolymer (Onyx).

PubMed

Uller, W; Müller-Wille, R; Loss, M; Hammer, S; Schleder, S; Goessmann, H; Wiggermann, P; Stroszczynski, C; Wohlgemuth, W A

2013-12-01

The management of postoperative bile leakage is challenging especially if the leak rises from the cut surface of the liver and endoscopic treatment fails. Percutaneous transhepatic treatment of bile leaks with biliary drainage is accepted but often requires long-term placement of the drains and is associated with treatment failures. This series evaluates selective embolization of bile ducts with an ethylene vinyl alcohol copolymer (Onyx) in patients with postoperative bile leaks as an alternative treatment option. Between January and September 2012, five consecutive patients with persistent postoperative bile leaks underwent percutaneous transhepatic Onyx application and were analyzed regarding procedural management, complications and success rates. The persistent bile leaks were situated at the cystic stump (after cholecystectomy, n = 2), at the cut surface of the liver (after extended liver resection, n = 2) and at the surface of the liver after surgical exploration and perihepatic abscess (n = 1). Bile drainage alone (endoscopic or percutaneous) failed in all patients and open redo-surgery was deemed potentially harmful. Bilomas were externally drained in all patients before Onyx application. For the closure of bile leaks, Onyx was injected through a microcatheter in a previously built coil nest to keep Onyx in place. All bile leaks were initially closed immediately. In the 2nd week after Onyx embolization, 2 patients showed recurrent small bile leaks without clinical symptoms. In the 4th week after Onyx application, all leaks were closed. No complications occurred. All leaking bile ducts were initially closed immediately after Onyx application. In the 2nd week after Onyx application, 2 patients showed small bile leaks without clinical symptoms. All leaks were closed in the 4th week after Onyx application. © Georg Thieme Verlag KG Stuttgart · New York.

Anastomotic leak after colorectal resection: A population-based study of risk factors and hospital variation.

PubMed

Nikolian, Vahagn C; Kamdar, Neil S; Regenbogen, Scott E; Morris, Arden M; Byrn, John C; Suwanabol, Pasithorn A; Campbell, Darrell A; Hendren, Samantha

2017-06-01

Anastomotic leak is a major source of morbidity in colorectal operations and has become an area of interest in performance metrics. It is unclear whether anastomotic leak is associated primarily with surgeons' technical performance or explained better by patient characteristics and institutional factors. We sought to establish if anastomotic leak could serve as a valid quality metric in colorectal operations by evaluating provider variation after adjusting for patient factors. We performed a retrospective cohort study of colorectal resection patients in the Michigan Surgical Quality Collaborative. Clinically relevant patient and operative factors were tested for association with anastomotic leak. Hierarchical logistic regression was used to derive risk-adjusted rates of anastomotic leak. Of 9,192 colorectal resections, 244 (2.7%) had a documented anastomotic leak. The incidence of anastomotic leak was 3.0% for patients with pelvic anastomoses and 2.5% for those with intra-abdominal anastomoses. Multivariable analysis showed that a greater operative duration, male sex, body mass index >30 kg/m 2 , tobacco use, chronic immunosuppressive medications, thrombocytosis (platelet count >400 × 10 9 /L), and urgent/emergency operations were independently associated with anastomotic leak (C-statistic = 0.75). After accounting for patient and procedural risk factors, 5 hospitals had a significantly greater incidence of postoperative anastomotic leak. This population-based study shows that risk factors for anastomotic leak include male sex, obesity, tobacco use, immunosuppression, thrombocytosis, greater operative duration, and urgent/emergency operation; models including these factors predict most of the variation in anastomotic leak rates. This study suggests that anastomotic leak can serve as a valid metric that can identify opportunities for quality improvement. Copyright © 2017 Elsevier Inc. All rights reserved.

What is the optimal management of an intra-operative air leak in a colorectal anastomosis?

PubMed

Mitchem, J B; Stafford, C; Francone, T D; Roberts, P L; Schoetz, D J; Marcello, P W; Ricciardi, R

2018-02-01

An airtight anastomosis on intra-operative leak testing has been previously demonstrated to be associated with a lower risk of clinically significant postoperative anastomotic leak following left-sided colorectal anastomosis. However, to date, there is no consistently agreed upon method for management of an intra-operative anastomotic leak. Therefore, we powered a noninferiority study to determine whether suture repair alone was an appropriate strategy for the management of an intra-operative air leak. This is a retrospective cohort analysis of prospectively collected data from a tertiary care referral centre. We included all consecutive patients with left-sided colorectal or ileorectal anastomoses and evidence of air leak during intra-operative leak testing. Patients were excluded if proximal diversion was planned preoperatively, a pre-existing proximal diversion was present at the time of surgery or an anastomosis was ultimately unable to be completed. The primary outcome measure was clinically significant anastomotic leak, as defined by the Surgical Infection Study Group at 30 days. From a sample of 2360 patients, 119 had an intra-operative air leak during leak testing. Sixty-eight patients underwent suture repair alone and 51 underwent proximal diversion or anastomotic reconstruction. The clinically significant leak rate was 9% (6/68; 95% CI: 2-15%) in the suture repair alone arm and 0% (0/51) in the diversion or reconstruction arm. Suture repair alone does not meet the criteria for noninferiority for the management of intra-operative air leak during left-sided colorectal anastomosis. Further repair of intra-operative air leak by suture repair alone should be reconsidered given these findings. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.

Clinical Factors and Postoperative Impact of Bile Leak After Liver Resection.

PubMed

Martin, Allison N; Narayanan, Sowmya; Turrentine, Florence E; Bauer, Todd W; Adams, Reid B; Stukenborg, George J; Zaydfudim, Victor M

2018-04-01

Despite technical advances, bile leak remains a significant complication after hepatectomy. The current study uses a targeted multi-institutional dataset to characterize perioperative factors that are associated with bile leakage after hepatectomy to better understand the impact of bile leak on morbidity and mortality. Adult patients in the 2014-2015 ACS NSQIP targeted hepatectomy dataset were linked to the ACS NSQIP PUF dataset. Bivariable and multivariable regression analyses were used to assess the associations between clinical factors and post-hepatectomy bile leak. Of 6859 patients, 530 (7.7%) had a postoperative bile leak. Proportion of bile leaks was significantly greater in patients after major compared to minor hepatectomy (12.6 vs. 5.1%, p < 0.001). The proportion of patients with bile leak was significantly greater in patients after major hepatectomy who had concomitant enterohepatic reconstruction (31.8 vs. 10.1%, p < 0.001). Postoperative mortality was significantly greater in patients with bile leaks (6.0 vs. 1.7%, p < 0.001). After adjusting for significant covariates, bile leak was independently associated with increased risk of postoperative morbidity (OR = 4.55; 95% CI 3.72-5.56; p < 0.001). After adjusting for significant effects of postoperative complications, liver failure, and reoperation (all p<0.001), bile leak was not independently associated with increased risk of postoperative mortality (p = 0.262). Major hepatectomy and enterohepatic biliary reconstruction are associated with significantly greater rates of bile leak after liver resection. Bile leak is independently associated with significant postoperative morbidity. Mitigation of bile leak is critical in reducing morbidity and mortality after liver resection.

Fluid pipeline leak detection and location with miniature RF tags

DOEpatents

McIntyre, Timothy J.

2017-05-16

Sensors locate troublesome leaks in pipes or conduits that carry a flowing medium. These sensors, through tailored physical and geometric properties, preferentially seek conduit leaks or breaches due to flow streaming. The sensors can be queried via transceivers outside the conduit or located and interrogated inside by submersible unmanned vehicle to identify and characterize the nature of a leak. The sensors can be functionalized with other capabilities for additional leak and pipeline characterization if needed. Sensors can be recovered from a conduit flow stream and reused for future leak detection activities.

Leak testing and repair of fusion devices

NASA Astrophysics Data System (ADS)

Kozman, T. A.

1983-06-01

The leak testing, reporting and vacuum leak repair techniques of the MPTF yin-yang number one magnet system, the world's largest superconducting magnet system, are discussed. Based on this experience, techniques are developed for testing and repairing leaks on the 42 MPTF-B magnets. The leak hunting techniques for the yin-yang magnet systems were applied to two helium circuits (the coil bundle and guard vacuum; both require helium flow for magnet cooldown). Additionally, during MPTF-B operation there are warm water plasma shields and piping that require leak checking.

Activation of Organic Photovoltaic Light Detectors Using Bend Leakage from Optical Fibers.

PubMed

Griffith, Matthew J; Willis, Matthew S; Kumar, Pankaj; Holdsworth, John L; Bezuidenhout, Henco; Zhou, Xiaojing; Belcher, Warwick; Dastoor, Paul C

2016-03-01

This work investigates the detection and subsequent utilization of leaked light from bends in a silica optical fiber using organic photovoltaic detectors. The optic power lost by single mode and multimode silica optical fibers was calibrated for bend radii between 1 and 7 mm for 532 and 633 nm light, exhibiting excellent agreement with previous theoretical solutions. The spatial location of maximum power leakage on the exterior of the fiber was found to exist in the same plane as the fiber, with a 10° offset from the normal. Two different organic photovoltaic detectors fabricated using a poly(3-hexylthiophene):indene-C60-bisadduct donor-acceptor blend cast from chloroform and chlorobenzene were fabricated to detect the leaked light. The two detectors exhibited different photovoltaic performances, predominantly due to different active layer thicknesses. Both devices showed sensitivity to leakage light, exhibiting voltages between 200 and 300 mV in response to leaked light from the fiber. The temporal responses of the devices were observed to differ, with a rise time from 10% to 90% of maximum voltage of 1430 μs for the chlorobenzene device, and a corresponding rise time of 490 μs for the higher performing chloroform device. The two OPVs were used to simultaneously detect leaked light from induced bends in the optical fiber, with the differing temporal profiles employed to create a unique time-correlated detection signal with enhanced security. The delay between detection of each OPV voltage could be systematically varied, allowing for either a programmable and secure single detection signal or triggering of multiple events with variable time resolution. The results reported in this study present exciting avenues toward the deployment of this simple and noninvasive optical detection system in a range of different applications.

[Management of cerebrospinal fluid leaks according to size. Our experience].

PubMed

Alobid, Isam; Enseñat, Joaquim; Rioja, Elena; Enriquez, Karla; Viscovich, Liza; de Notaris, Matteo; Bernal-Sprekelsen, Manuel

2014-01-01

We present our experience in the reconstruction of cerebrospinal fluid (CSF) leaks according to their size and location. Fifty-four patients who underwent advanced skull base surgery (large defects) and 62 patients with CSF leaks of different origin (small and medium-sized defects) were included. Large defects were reconstructed with a nasoseptal pedicled flap positioned on fat and fascia lata and lumbar drainage was used. In small and medium-sized leaks of other origin, intrathecal fluorescein 5% was applied previously to identify the defect. Fascia lata in an underlay position was used for reconstruction, which was then covered with mucoperiosteum from the turbinate. Perioperative antibiotics were administered for 5-7 days. Nasal packing was removed after 24-48 hours. The most frequent aetiology for small and medium-sized defects was spontaneous (48.4%), followed by trauma (24.2%), iatrogenic (5%) and others. The success rate was of 91% after the first surgery and 98% in large skull base defects and small/medium-sized respectively. After rescue surgery, the rate of closure achieved was 100%. The follow-up was 15.6 ± 12.4 months for large defects and 75.3 ± 51.3 months for small/medium-sized defects without recurrence. Endoscopic surgery for closure of any type of skull base defect is the gold standard approach. Defect size does not play a significant role in the success rate. Fascia lata and mucoperiosteum allow a reconstruction of small/medium-sized defects. For larger skull base defects, a combination of fat, fascia lata and nasoseptal pedicled flaps provide a successful reconstruction. Copyright © 2013 Elsevier España, S.L. All rights reserved.

Sleeve gastrectomy and the risk of leak: a systematic analysis of 4,888 patients.

PubMed

Aurora, Alexander R; Khaitan, Leena; Saber, Alan A

2012-06-01

Sleeve gastrectomy has become a popular stand-alone bariatric procedure with comparable weight loss and resolution of comorbidities to that of laparoscopic gastric bypass. The simplicity of the procedure and the decreased long-term risk profile make this surgery more appealing. Nonetheless, the ever present risk of a staple-line leak is still of great concern and needs further investigation. An electronic literature search of MEDLINE database plus manual reference checks of articles published on laparoscopic sleeve gastrectomy for morbid obesity and its complications was completed. Keywords used in the search were "sleeve gastrectomy" OR "gastric sleeve" AND "leak." We analyzed 29 publications, including 4,888 patients. We analyzed the frequency of leak after sleeve gastrectomy and its associated risks of causation. The risk of leak after sleeve gastrectomy in all comers was 2.4%. This risk was 2.9% in the super-obese [body mass index (BMI) > 50 kg/m(2)] and 2.2% for BMI < 50 kg/m(2). Staple height and use of buttressing material did not affect leak rate. The use of a size 40-Fr or greater bougie was associated with a leak rate of 0.6% compared with those who used smaller sizes whose leak rate was 2.8%. Leaks were found at the proximal third of the stomach in 89% of cases. Most leaks were diagnosed after discharge. Endoscopic management is a viable option for leaks and was documented in 11% of cases as successful. Sleeve gastrectomy has become an important surgical option for the treatment of the ever growing morbidly obese population. The risk of leak is low at 2.4%. Attention to detail specifically at the esophagogastric junction cannot be stressed enough. Careful patient selection (BMI < 50 kg/m(2)) and adopting the use of a 40-Fr or larger bougie may decrease the risk of leak. Vigilant follow-up during the first 30 days is critical to avoid catastrophe, because most leaks will happen after patient discharge.

Noble Gas Leak Detector for Use in the SNS Neutron Electric Dipole Moment Experiment

NASA Astrophysics Data System (ADS)

Barrow, Chad; Huffman, Paul; Leung, Kent; Korobkina, Ekaterina; White, Christian; nEDM Collaboration Collaboration

2017-09-01

Common practice for leak-checking high vacuum systems uses helium as the probing gas. However, helium may permeate some materials at room temperature, making leak characterization difficult. The experiment to find a permanent electric dipole moment of the neutron (nEDM), to be conducted at Oak Ridge National Laboratories, will employ a large volume of liquid helium housed by such a helium-permeable composite material. It is desirable to construct a leak detector that can employ alternative test gases. The purpose of this experiment is to create a leak detector that can quantify the argon gas flux in a high vacuum environment and interpret this flux as a leak-rate. This apparatus will be used to check the nEDM volumes for leaks at room temperature before cooling down to cryogenic temperatures. Our leak detector uses a residual gas analyzer and a vacuum pumping station to characterize the gas present in an evacuated volume. The introduction of argon gas into the system is interpreted as a leak-rate into the volume. The device has been calibrated with NIST certified calibrated leaks and the machine's sensitivity has been calculated using background gas analysis. As a result of the device construction and software programming, we are able to leak-check composite and polyamide volumes This work was supported in part by the US Department of Energy under Grant No. DE-FG02-97ER41042.

A simple web-based risk calculator (www.anastomoticleak.com) is superior to the surgeon's estimate of anastomotic leak after colon cancer resection.

PubMed

Sammour, T; Lewis, M; Thomas, M L; Lawrence, M J; Hunter, A; Moore, J W

2017-01-01

Anastomotic leak can be a devastating complication, and early prediction is difficult. The aim of this study is to prospectively validate a simple anastomotic leak risk calculator and compare its predictive value with the estimate of the primary operating surgeon. Consecutive patients undergoing elective or emergency colon cancer surgery with a primary anastomosis over a 1-year period were prospectively included. A recently published anastomotic leak risk nomogram was converted to an online calculator ( www.anastomoticleak.com ). The calculator-derived risk of anastomotic leak and the risk estimated by the primary operating surgeon were recorded at the completion of surgery. The primary outcome was anastomotic leak within 90 days as defined by previously published criteria. Area under receiver operating characteristic curve analysis (AUROC) was performed for both risk estimates. A total of 105 patients were screened for inclusion during the study period, of whom 83 met the inclusion criteria. The overall anastomotic leak rate was 9.6%. The anastomotic leak calculator was highly predictive of anastomotic leak (AUROC 0.84, P = 0.002), whereas the surgeon estimate was not predictive (AUROC 0.40, P = 0.243). A simple anastomotic leak risk calculator is significantly better at predicting anastomotic leak than the estimate of the primary surgeon. Further external validation on a larger data set is required.

Leak Detection in Spacecraft Using a 64-Element Multiplexed Passive Array to Monitor Structure-Borne Noise

NASA Astrophysics Data System (ADS)

Holland, Stephen D.; Song, Jun-Ho; Chimenti, D. E.; Roberts, Ron

2006-03-01

We demonstrate an array sensor method intended to locate leaks in manned spacecraft using leak-generated, structure-borne ultrasonic noise. We have developed and tested a method for sensing and processing leak noise to reveal the leak location involving the use of a 64-element phased-array. Cross-correlations of ultrasonic noise waveforms from a leak into vacuum have been used with a phased-array analysis to find the direction from the sensor to the leak. This method measures the propagation of guided ultrasonic Lamb waves passing under the PZT array sensor in the spacecraft skin structure. This paper will describe the custom-designed array with integrated electronics, as well as the performance of the array in prototype applications. We show that this method can be used to successfully locate leaks to within a few millimeters on a 0.6-m square aluminum plate.

Comprehensive Quantitative Analysis on Privacy Leak Behavior

PubMed Central

Fan, Lejun; Wang, Yuanzhuo; Jin, Xiaolong; Li, Jingyuan; Cheng, Xueqi; Jin, Shuyuan

2013-01-01

Privacy information is prone to be leaked by illegal software providers with various motivations. Privacy leak behavior has thus become an important research issue of cyber security. However, existing approaches can only qualitatively analyze privacy leak behavior of software applications. No quantitative approach, to the best of our knowledge, has been developed in the open literature. To fill this gap, in this paper we propose for the first time four quantitative metrics, namely, possibility, severity, crypticity, and manipulability, for privacy leak behavior analysis based on Privacy Petri Net (PPN). In order to compare the privacy leak behavior among different software, we further propose a comprehensive metric, namely, overall leak degree, based on these four metrics. Finally, we validate the effectiveness of the proposed approach using real-world software applications. The experimental results demonstrate that our approach can quantitatively analyze the privacy leak behaviors of various software types and reveal their characteristics from different aspects. PMID:24066046

Comprehensive quantitative analysis on privacy leak behavior.

PubMed

Fan, Lejun; Wang, Yuanzhuo; Jin, Xiaolong; Li, Jingyuan; Cheng, Xueqi; Jin, Shuyuan

2013-01-01

Privacy information is prone to be leaked by illegal software providers with various motivations. Privacy leak behavior has thus become an important research issue of cyber security. However, existing approaches can only qualitatively analyze privacy leak behavior of software applications. No quantitative approach, to the best of our knowledge, has been developed in the open literature. To fill this gap, in this paper we propose for the first time four quantitative metrics, namely, possibility, severity, crypticity, and manipulability, for privacy leak behavior analysis based on Privacy Petri Net (PPN). In order to compare the privacy leak behavior among different software, we further propose a comprehensive metric, namely, overall leak degree, based on these four metrics. Finally, we validate the effectiveness of the proposed approach using real-world software applications. The experimental results demonstrate that our approach can quantitatively analyze the privacy leak behaviors of various software types and reveal their characteristics from different aspects.

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

40 CFR 63.1086 - How must I monitor for leaks to cooling water?

Code of Federal Regulations, 2010 CFR

2010-07-01

... monitor for leaks to cooling water? You must monitor for leaks to cooling water by monitoring each heat... system so that the cooling water flow rate is 51,031 liters per minute or less so that a leak of 3.06 kg... detected a leak. (b) Individual heat exchangers. Monitor the cooling water at the entrance and exit of each...

40 CFR 264.196 - Response to leaks or spills and disposition of leaking or unfit-for-use tank systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Response to leaks or spills and... HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Tank Systems § 264.196 Response to leaks or... system from which there has been a leak or spill, or which is unfit for use, must be removed from service...

Temperature and Atomic Oxygen Effects on Helium Leak Rates of a Candidate Main Interface Seal

NASA Technical Reports Server (NTRS)

Penney, Nicholas; Wasowski, Janice L.; Daniels, Christopher C.

2011-01-01

Helium leak tests were completed to characterize the leak rate of a 54 in. diameter composite space docking seal design in support of the National Aeronautics and Space Administration s (NASA's) Low Impact Docking System (LIDS). The evaluated seal design was a candidate for the main interface seal on the LIDS, which would be compressed between two vehicles, while docked, to prevent the escape of breathable air from the vehicles and into the vacuum of space. Leak tests completed at nominal temperatures of -30, 20, and 50 C on untreated and atomic oxygen (AO) exposed test samples were examined to determine the influence of both test temperature and AO exposure on the performance of the composite seal assembly. Results obtained for untreated seal samples showed leak rates which increased with increased test temperature. This general trend was not observed in tests of the AO exposed specimens. Initial examination of collected test data suggested that AO exposure resulted in higher helium leak rates, however, further analysis showed that the differences observed in the 20 and 50 C tests between the untreated and AO exposed samples were within the experimental error of the test method. Lack of discernable trends in the test data prevented concrete conclusions about the effects of test temperature and AO exposure on helium leak rates of the candidate seal design from being drawn. To facilitate a comparison of the current test data with results from previous leak tests using air as the test fluid, helium leak rates were converted to air leak rates using standard conversion factors for viscous and molecular flow. Flow rates calculated using the viscous flow conversion factor were significantly higher than the experimental air leakage values, whereas values calculated using the molecular flow conversion factor were significantly lower than the experimentally obtained air leak rates. The difference in these sets of converted flow rates and their deviation from the experimentally obtained air leak rate data suggest that neither conversion factor can be used alone to accurately convert helium leak rates to equivalent air leak rates for the test seals evaluated in this study; other leak phenomena, including permeation, must also be considered.

Sensitivity and specificity of intrathecal fluorescein and white light excitation for detecting intraoperative cerebrospinal fluid leak in endoscopic skull base surgery: a prospective study.

PubMed

Raza, Shaan M; Banu, Matei A; Donaldson, Angela; Patel, Kunal S; Anand, Vijay K; Schwartz, Theodore H

2016-03-01

The intraoperative detection of CSF leaks during endonasal endoscopic skull base surgery is critical to preventing postoperative CSF leaks. Intrathecal fluorescein (ITF) has been used at varying doses to aid in the detection of intraoperative CSF leaks. However, the sensitivity and specificity of ITF at certain dosages is unknown. A prospective database of all endoscopic endonasal procedures was reviewed. All patients received 25 mg ITF diluted in 10 ml CSF and were pretreated with dexamethasone and Benadryl. Immediately after surgery, the operating surgeon prospectively noted if there was an intraoperative CSF leak and fluorescein was identified. The sensitivity, specificity, and positive and negative predictive power of ITF for detecting intraoperative CSF leak were calculated. Factors correlating with postoperative CSF leak were determined. Of 419 patients, 35.8% of patients did not show a CSF leak. Fluorescein-tinted CSF (true positive) was noted in 59.7% of patients and 0 false positives were encountered. CSF without fluorescein staining (false negative) was noted in 4.5% of patients. The sensitivity and specificity of ITF were 92.9% and 100%, respectively. The negative and positive predictive values were 88.8% and 100%, respectively. Postoperative CSF leaks only occurred in true positives at a rate of 2.8%. ITF is extremely specific and very sensitive for detecting intraoperative CSF leaks. Although false negatives can occur, these patients do not appear to be at risk for postoperative CSF leak. The use of ITF may help surgeons prevent postoperative CSF leaks by intraoperatively detecting and confirming a watertight repair.

Risk factors for cerebrospinal fluid leak in pediatric patients undergoing endoscopic endonasal skull base surgery.

PubMed

Stapleton, Amanda L; Tyler-Kabara, Elizabeth C; Gardner, Paul A; Snyderman, Carl H; Wang, Eric W

2017-02-01

To determine the risk factors associated with cerebrospinal fluid (CSF) leak following endoscopic endonasal surgery (EES) for pediatric skull base lesions. Retrospective chart review of pediatric patients (ages 1 month to 18 years) treated for skull base lesions with EES from 1999 to 2014. Five pathologies were reviewed: craniopharyngioma, clival chordoma, pituitary adenoma, pituitary carcinoma, and Rathke's cleft cyst. Fisher's exact tests were used to evaluate the different factors to determine which had a statistically higher risk of leading to a post-operative CSF leak. 55 pediatric patients were identified who underwent 70 EES's for tumor resection. Of the 70 surgeries, 47 surgeries had intraoperative CSF leaks that were repaired at the time of surgery. 11 of 47 (23%) surgeries had post-operative CSF leaks that required secondary operative repair. Clival chordomas had the highest CSF leak rate at 36%. There was no statistical difference in leak rate based on the type of reconstruction, although 28% of cases that used a vascularized flap had a post-operative leak, whereas only 9% of those cases not using a vascularized flap had a leak. Post-operative hydrocephalus and perioperative use of a lumbar drain were not significant risk factors. Pediatric patients with an intra-operative CSF leak during EES of the skull base have a high rate of post-operative CSF leaks. Clival chordomas appear to be a particularly high-risk group. The use of vascularized flaps and perioperative lumbar drains did not statistically decrease the rate of post-operative CSF leak. Copyright © 2017 Elsevier B.V. All rights reserved.

Examinations for leak tightness of actively cooled components in ITER and fusion devices

NASA Astrophysics Data System (ADS)

Hirai, T.; Barabash, V.; Carrat, R.; Chappuis, Ph; Durocher, A.; Escourbiac, F.; Merola, M.; Raffray, R.; Worth, L.; Boscary, J.; Chantant, M.; Chuilon, B.; Guilhem, D.; Hatchressian, J.-C.; Hong, S. H.; Kim, K. M.; Masuzaki, S.; Mogaki, K.; Nicolai, D.; Wilson, D.; Yao, D.

2017-12-01

Any leak in one of the ITER actively cooled components would cause significant consequences for machine operations; therefore, the risk of leak must be minimized as much as possible. In this paper, the strategy of examination to ensure leak tightness of the ITER internal components (i.e. examination of base materials, vacuum boundary joints and final components) and the hydraulic parameters for ITER internal components are summarized. The experiences of component tests, especially hot helium leak tests in recent fusion devices, were reviewed and the parameters were discussed. Through these experiences, it was confirmed that the hot He leak test was effective to detect small leak paths which were not always possible to detect by volumetric examination due to limited spatial resolution.

Biphasic decay of the Ca transient results from increased sarcoplasmic reticulum Ca leak

PubMed Central

Sankaranarayanan, Rajiv; Li, Yatong; Greensmith, David J.; Eisner, David A.

2016-01-01

Key points Ca leak from the sarcoplasmic reticulum through the ryanodine receptor (RyR) reduces the amplitude of the Ca transient and slows its rate of decay.In the presence of β‐adrenergic stimulation, RyR‐mediated Ca leak produces a biphasic decay of the Ca transient with a fast early phase and a slow late phase.Two forms of Ca leak have been studied, Ca‐sensitising (induced by caffeine) and non‐sensitising (induced by ryanodine) and both induce biphasic decay of the Ca transient.Only Ca‐sensitising leak can be reversed by traditional RyR inhibitors such as tetracaine.Ca leak can also induce Ca waves. At low levels of leak, waves occur. As leak is increased, first biphasic decay and then slowed monophasic decay is seen. The level of leak has major effects on the shape of the Ca transient. Abstract In heart failure, a reduction in Ca transient amplitude and contractile dysfunction can by caused by Ca leak through the sarcoplasmic reticulum (SR) Ca channel (ryanodine receptor, RyR) and/or decreased activity of the SR Ca ATPase (SERCA). We have characterised the effects of two forms of Ca leak (Ca‐sensitising and non‐sensitising) on calcium cycling and compared with those of SERCA inhibition. We measured [Ca2+]i with fluo‐3 in voltage‐clamped rat ventricular myocytes. Increasing SR leak with either caffeine (to sensitise the RyR to Ca activation) or ryanodine (non‐sensitising) had similar effects to SERCA inhibition: decreased systolic [Ca2+]i, increased diastolic [Ca2+]i and slowed decay. However, in the presence of isoproterenol, leak produced a biphasic decay of the Ca transient in the majority of cells while SERCA inhibition produced monophasic decay. Tetracaine reversed the effects of caffeine but not of ryanodine. When caffeine (1 mmol l−1) was added to a cell which displayed Ca waves, the wave frequency initially increased before waves disappeared and biphasic decay developed. Eventually (at higher caffeine concentrations), the biphasic decay was replaced by slow decay. We conclude that, in the presence of adrenergic stimulation, Ca leak can produce biphasic decay; the slow phase results from the leak opposing Ca uptake by SERCA. The degree of leak determines whether decay of Ca waves, biphasic or monophasic, occurs. PMID:26537441

Method and apparatus for container leakage testing

DOEpatents

Kronberg, James W.

1995-01-01

An apparatus for use in one-hundred percent leak testing of food containers used in conjunction with a tracer gas. The apparatus includes a shell with entrance and exit air locks to create a controlled atmosphere through which a series of containers is conveyed by a conveyor belt. The pressure in the shell is kept lower than the pressure in the containers and the atmosphere is made to flow with the containers so that a tracer gas placed in the packages before sealing them will leak more readily, but the leaked tracer gas will remain associated with the leaking package as it moves through the shell. The leaks are detected with a sniffer probe in fluid communication with a gas chromatograph. The gas chromatograph issues a signal when it detects a leak to an ejector that will eject the leaking container from the conveyor. The system is timed so that the series of containers can move continuously into and out of the shell, past the probe and the ejector, without stopping, yet each package is tested for leaks and removed if leaking.

Distribution System Audits, Leak Detection, and Repair: Kirtland Air Force Base Leak Detection and Repair Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Water Best Management Practice #3 Fact Seet: Outlines how a leak detection and repair program helped Kirtland Air Force Base perform distribution system audits, leak detection, and repair to conserve water site-wide.

Double Shell Tank AY-102 Radioactive Waste Leak Investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Washenfelder, Dennis J.

2014-04-10

PowerPoint. The objectives of this presentation are to: Describe Effort to Determine Whether Tank AY-102 Leaked; Review Probable Causes of the Tank AY-102 Leak; and, Discuss Influence of Leak on Hanford’s Double-Shell Tank Integrity Program.

Method and means of passive detection of leaks in buried pipes

DOEpatents

Claytor, T.

1979-10-30

A method and means for passive detection of a leak in a buried pipe containing fluid under pressure includes a plurality of acoustic detectors that are placed in contact with the pipe. Noise produced by the leak is detected by the detectors, and the detected signals are correlated to locate the leak. In one embodiment of the invention two detectors are placed at different locations to locate a leak between them. In an alternate embodiment two detectors of different waves are placed at substantially the same location to determine the distance of the leak from the location.

Method and means of passive detection of leaks in buried pipes

DOEpatents

Claytor, Thomas N.

1981-01-01

A method and means for passive detection of a leak in a buried pipe containing fluid under pressure includes a plurality of acoustic detectors that are placed in contact with the pipe. Noise produced by the leak is detected by the detectors, and the detected signals are correlated to locate the leak. In one embodiment of the invention two detectors are placed at different locations to locate a leak between them. In an alternate embodiment two detectors of different waves are placed at substantially the same location to determine the distance of the leak from the location.

Leak testing in parenteral packaging: establishment of direct correlation between helium leak rate measurements and microbial ingress for two different leak types.

PubMed

Morrical, Bradley D; Goverde, Marcel; Grausse, Jean; Gerwig, Tanja; Vorgrimler, Lothar; Morgen, Rachel; Büttiker, Jean-Pierre

2007-01-01

A direct test method using helium leak detection was developed to determine microbial ingress in parenteral vial/rubber closure systems. The purpose of this study was to establish a direct correlation between the helium leak rate and the presence of ingress when vials were submersed under pressure in a broth of bacteria. Results were obtained for two different types of leaks: microholes that have been laser-drilled into thin metal plates, and thin copper wire that was placed between the rubber closure and the glass vial's sealing surface. The results from the microholes showed that the helium leak rate was a function of the square of the hole diameter and fit well with theoretical calculations. The relationship with the wire gave a far more complex dependence and was not modeled theoretically. Comparison with the microbial challenge showed that for microholes a lower size limit was found to be 2 microm with a corresponding leak rate of 1.4 x 10(-3) mbarl/s. For the fine wire experiment the lower limit was 15-microm wire and a corresponding leak rate of 1.3 x 10(-5) mbarl/s. From these tests a safe, lower limit, leak rate was established.

Transepithelial leak in Barrett's esophagus patients: The role of proton pump inhibitors

PubMed Central

Farrell, Christopher; Morgan, Melissa; Tully, Owen; Wolov, Kevin; Kearney, Keith; Ngo, Benjamin; Mercogliano, Giancarlo; Thornton, James J; Valenzano, Mary Carmen; Mullin, James M

2012-01-01

AIM: To determine if the observed paracellular sucrose leak in Barrett’s esophagus patients is due to their proton pump inhibitor (PPI) use. METHODS: The in vivo sucrose permeability test was administered to healthy controls, to Barrett’s patients and to non-Barrett’s patients on continuous PPI therapy. Degree of leak was tested for correlation with presence of Barrett’s, use of PPIs, and length of Barrett’s segment and duration of PPI use. RESULTS: Barrett’s patients manifested a near 3-fold greater, upper gastrointestinal sucrose leak than healthy controls. A decrease of sucrose leak was observed in Barrett’s patients who ceased PPI use for 7 d. Although initial introduction of PPI use (in a PPI-naïve population) results in dramatic increase in sucrose leak, long-term, continuous PPI use manifested a slow spontaneous decline in leak. The sucrose leak observed in Barrett’s patients showed no correlation to the amount of Barrett’s tissue present in the esophagus. CONCLUSION: Although future research is needed to determine the degree of paracellular leak in actual Barrett’s mucosa, the relatively high degree of leak observed with in vivo sucrose permeability measurement of Barrett’s patients reflects their PPI use and not their Barrett’s tissue per se. PMID:22719187

Drain amylase aids detection of anastomotic leak after esophagectomy.

PubMed

Baker, Erin H; Hill, Joshua S; Reames, Mark K; Symanowski, James; Hurley, Susie C; Salo, Jonathan C

2016-04-01

Anastomotic leak following esophagectomy is associated with significant morbidity and mortality. As hospital length of stay decreases, the timely diagnosis of leak becomes more important. We evaluated CT esophagram, white blood count (WBC), and drain amylase levels in the early detection of anastomotic leak. The diagnostic performance of CT esophagram, drain amylase >800 IU/L, and WBC >12,000/µL within the first 10 days after surgery in predicting leak at any time after esophagectomy was calculated. Anastomotic leak occurred in 13 patients (13%). CT esophagram performed within 10 days of surgery diagnosed six of these leaks with a sensitivity of 0.54. Elevation in drain amylase level within 10 days of surgery diagnosed anastomotic leak with a sensitivity of 0.38. When the CT esophagram and drain amylase were combined, the sensitivity rose to 0.69 with a specificity of 0.98. WBC elevation had a sensitivity of 0.92, with a specificity of 0.34. Among 30 patients with normal drain amylase and a normal WBC, one developed an anastomotic leak. Drain amylase adds to the sensitivity of CT esophagram in the early detection of anastomotic leak. Selected patients with normal drain amylase levels and normal WBC may be able to safely forgo CT esophagram.

Cerebrospinal fluid rhinorrhea following trans-sphenoidal pituitary macroadenoma surgery: experience from 592 patients.

PubMed

Han, Zong-Li; He, Dong-Sheng; Mao, Zhi-Gang; Wang, Hai-Jun

2008-06-01

To determine the incidence, risk factors, diagnostic procedures, and management of cerebrospinal fluid (CSF) leaks following trans-sphenoidal pituitary macroadenoma surgery. Retrospective analysis of 592 patients. Intra- and post-operative CSF leaks occurred in 14.2 and 4.4% of patients, respectively. Surgical revision, tumor consistency, and tumor margins were independently associated with intra-operative leaks, while the tumor size, consistency, and margins were risk factors of post-operative leaks. The intra-operative leak rate of ACTH adenomas was greater than all other types combined; the incidence of post-operative CSF leaks was highest for FSH adenomas. There were no significant differences among various techniques and we achieved an initial repair success rates of 83.3 and 92.9% for intra- and post-operative CSF leaks, respectively. Of the 26 patients with post-operative CSF leaks, five were complicated by meningitis and four by post-infectious hydrocephalus which required ventriculoperitoneal shunts. CSF leaks have a propensity to occur in cases with fibrous tumors or tumors with indistinct margin and may have some relationship with the tumor type. Endoscopic and microscopic repairs were shown to be effective techniques in managing these types of leaks. Post-infectious hydrocephalus may influence the outcome of the repair and ventriculoperitoneal shunts were necessary in some cases.

Seven Ventilators Challenged With Leaks During Neonatal Nasal CPAP: An Experimental Pilot Study.

PubMed

Drevhammar, Thomas; Nilsson, Kjell; Zetterström, Henrik; Jonsson, Baldvin

2015-07-01

Nasal CPAP is the most common respiratory support for neonates. Several factors are considered important for effective treatment, including leaks at the patient interface and the delivery of pressure-stable CPAP. Investigations of pressure stability during leaks should include both the change in the mean delivered CPAP and the pressure variation during each breath. The aim of this study was to examine the response of ventilators delivering nasal CPAP when challenged with leaks at the patient interface. Seven ventilators providing nasal CPAP at 4 cm H2O were challenged with leaks during simulated neonatal breathing. Leak was applied for 15 consecutive breaths at a constant level (1-4 L/min). The 2 aspects of pressure stability were evaluated by measuring the mean delivered CPAP and the amplitude of pressure swings before, during, and after leaks. The ability to maintain the delivered CPAP and the amplitude of pressure swings varied greatly among the 7 ventilators before, during, and after leaks. Four of the ventilators tested have built-in leak compensation. There was no simple relationship between maintaining delivered CPAP during leaks and providing CPAP with low pressure swing amplitude. Maintaining the delivered CPAP and providing this without pressure swings are 2 separate aspects of pressure stability, and investigations concerning the clinical importance of pressure stability should address both aspects. This study also shows that compensation for leaks does not necessarily provide pressure-stable CPAP. Copyright © 2015 by Daedalus Enterprises.

Long-life leak standard assembly

DOEpatents

Basford, James A.; Mathis, John E.; Wright, Harlan C.

1982-01-01

The present invention is directed to a portable leak standard assembly which is capable of providing a stream of high-purity reference gas at a virtually constant flow rate over an extensive period of time. The leak assembly comprises a high pressure reservoir coupled to a metal leak valve through a valve-controlled conduit. A reproducible leak valve useful in this assembly is provided by a metal tube crimped with a selected pressure loading for forming an orifice in the tube with this orifice being of a sufficient size to provide the selected flow rate. The leak valve assembly is formed of metal so that it can be "baked-out" in a vacuum furnace to rid the reservoir and attendent components of volatile impurities which reduce the efficiency of the leak standard.

Long-life leak standard assembly. [Patent application

DOEpatents

Basford, J.A.; Mathis, J.E.; Wright, H.C.

1980-11-12

The present invention is directed to a portable leak standard assembly which is capable of providing a stream of high-purity reference gas at a virtually constant flow rate over an extensive period of time. The leak assembly comprises a high pressure reservoir coupled to a metal leak valve through a valve-controlled conduit. A reproducible leak valve useful in this assembly is provided by a metal tube crimped with a selected pressure loading for forming an orifice in the tube with this orifice being of a sufficient size to provide the selected flow rate. The leak valve assembly is formed of metal so that it can be baked-out in a vacuum furnace to rid the reservoir and attendent components of volatile impurities which reduce the efficiency of the leak standard.

Comprehensive leak detection survey and benefit/cost analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholze, R.J. Jr.; Maloney, S.W.

1995-06-01

Fort Carson, Colorado was the site of a comprehensive leak detection investigation of the potable water system with the express purpose of quantifying the benefits to be derived by a military installation from use of leak detection and repair technology. Military bases are often the size of a small city and one Directorate or Department has responsibility for all real estate (buildings, roads, grounds, etc.) unlike a municipal public works department. The investigation used state of the art noise correlation and computer correlation technology to survey the distribution system mains. This was complemented by a building to building survey coveringmore » office and commercial buildings along with family and barracks housing where investigators entered buildings and quantified visible leaks in faucets and water closets, etc. Following repairs and a year`s time, a follow-on survey is performed to again examine all aspects of the system. The result was a complete economic evaluation and benefit/cost analysis of the installation. Representative findings include: the majority of distribution system leaks were at hydrants or similar appurtenances; and family housing was found to be the other major concentration of leaks. However, where the first survey found 80 percent of housing units had leaks, findings from the second round on the order of 20 percent. Office buildings were found from the first survey to not merit follow-on attention due to limited numbers of leaks. Water-consciousness was raised for both the responsible directorate and individuals in family housing and leak repair was given a higher priority for repairs. This paper will outline the leak detection methodology used, characterize the types and patterns of leaks found, introduce an economic analysis for the entire leak detection process, and finally, provide lessons learned with practical results and implications.« less

Quantitative computed tomography versus spirometry in predicting air leak duration after major lung resection for cancer.

PubMed

Ueda, Kazuhiro; Kaneda, Yoshikazu; Sudo, Manabu; Mitsutaka, Jinbo; Li, Tao-Sheng; Suga, Kazuyoshi; Tanaka, Nobuyuki; Hamano, Kimikazu

2005-11-01

Emphysema is a well-known risk factor for developing air leak or persistent air leak after pulmonary resection. Although quantitative computed tomography (CT) and spirometry are used to diagnose emphysema, it remains controversial whether these tests are predictive of the duration of postoperative air leak. Sixty-two consecutive patients who were scheduled to undergo major lung resection for cancer were enrolled in this prospective study to define the best predictor of postoperative air leak duration. Preoperative factors analyzed included spirometric variables and area of emphysema (proportion of the low-attenuation area) that was quantified in a three-dimensional CT lung model. Chest tubes were removed the day after disappearance of the air leak, regardless of pleural drainage. Univariate and multivariate proportional hazards analyses were used to determine the influence of preoperative factors on chest tube time (air leak duration). By univariate analysis, site of resection (upper, lower), forced expiratory volume in 1 second, predicted postoperative forced expiratory volume in 1 second, and area of emphysema (< 1%, 1% to 10%, > 10%) were significant predictors of air leak duration. By multivariate analysis, site of resection and area of emphysema were the best independent determinants of air leak duration. The results were similar for patients with a smoking history (n = 40), but neither forced expiratory volume in 1 second nor predicted postoperative forced expiratory volume in 1 second were predictive of air leak duration. Quantitative CT is superior to spirometry in predicting air leak duration after major lung resection for cancer. Quantitative CT may aid in the identification of patients, particularly among those with a smoking history, requiring additional preventive procedures against air leak.

Postoperative air leak grading is useful to predict prolonged air leak after pulmonary lobectomy.

PubMed

Oh, Sang Gi; Jung, Yochun; Jheon, Sanghoon; Choi, Yunhee; Yun, Ju Sik; Na, Kook Joo; Ahn, Byoung Hee

2017-01-23

Results of studies to predict prolonged air leak (PAL; air leak longer than 5 days) after pulmonary lobectomy have been inconsistent and are of limited use. We developed a new scale representing the amount of early postoperative air leak and determined its correlation with air leak duration and its potential as a predictor of PAL. We grade postoperative air leak using a 5-grade scale. All 779 lobectomies from January 2005 to December 2009 with available medical records were reviewed retrospectively. We devised six 'SUM' variables using air leak grades in the initial 72 h postoperatively. Excluding unrecorded cases and postoperative broncho-pleural fistulas, there were 720 lobectomies. PAL occurred in 135 cases (18.8%). Correlation analyses showed each SUM variable highly correlated with air leak duration, and the SUM 4to9 , which was the sum of six consecutive values of air leak grades for every 8 h record on postoperative days 2 and 3, was proved to be the most powerful predictor of PAL; PAL could be predicted with 75.7% and 77.7% positive and negative predictive value, respectively, when SUM 4to9  ≥ 16. When 4 predictors derived from multivariable logistic regression of perioperative variables were combined with SUM 4to9 , there was no significant increase in predictability compared with SUM 4to9 alone. This simple new method to predict PAL using SUM 4to9 showed that the amount of early postoperative air leak is the most powerful predictor of PAL, therefore, grading air leak after pulmonary lobectomy is a useful method to predict PAL.

Efficacy and Safety of the Over-the-Scope Clip (OTSC) System in the Management of Leak and Fistula After Laparoscopic Sleeve Gastrectomy: a Systematic Review.

PubMed

Shoar, Saeed; Poliakin, Lauren; Khorgami, Zhamak; Rubenstein, Rebecca; El-Matbouly, Moamena; Levin, Jun L; Saber, Alan A

2017-09-01

Endoscopic management of leaks/fistulas after laparoscopic sleeve gastrectomy (LSG) is gaining popularity in the bariatric surgery. This study aimed to review the efficacy and safety of over-the-scope-clip (OTSC) system in endoscopic closure of post-LSG leak/fistula. PubMed/Medline and major journals of the field were systematically reviewed for studies on endoscopic closure of post-LSG leaks/fistula by means of the OTSC system. A total of ten eligible studies including 195 patients with post-LSG leaks/fistula were identified. The time between LSG and leak/fistula ranged from 1 day to 803 days. Most of the leaks/fistula were located at the proximal staple line, and they sized from 3 to 20 mm. Time between leak diagnosis and OTSC clipping ranged from 0 to 271 days. Thirty-three out of 53 patients (63.5%) required one clip for closure of the lesion. Regarding the OTSC-related complications, a leak occurred in five patients (9.3%) and OTSC migration, stenosis, and tear each in one patient (1.8%). Of the 73 patients with post-LSG leak treated with OTSC, 63 patients had an overall successful closure (86.3%). OTSC system is a promising endoscopic approach for management of post-LSG leaks in appropriately selected patients. Unfortunately, most studies are series with a small sample size, short-term follow-up, and mixed data of concomitant procedures with OTSC. Further studies should distinguish the net efficacy of the OTSC system from other concomitant procedures in treatment of post-LSG leak.

Time-dependent phase shift of a retrieved pulse in off-resonant electromagnetically-induced-transparency-based light storage

NASA Astrophysics Data System (ADS)

Maynard, M.-A.; Bouchez, R.; Lugani, J.; Bretenaker, F.; Goldfarb, F.; Brion, E.

2015-11-01

We report measurements of the time-dependent phases of the leak and retrieved pulses obtained in electromagnetically-induced-transparency storage experiments with metastable helium vapor at room temperature. In particular, we investigate the influence of the optical detuning at two-photon resonance and provide numerical simulations of the full dynamical Maxwell-Bloch equations, which allow us to account for the experimental results.

Shrink-Fit Solderable Inserts Seal Hermetically

NASA Technical Reports Server (NTRS)

Croucher, William C.

1992-01-01

Shrink-fit stainless-steel insert in aluminum equipment housing allows electrical connectors to be replaced by soldering, without degrading hermeticity of housing or connector. Welding could destroy electrostatic-sensitive components and harm housing and internal cables. Steel insert avoids problems because connector soldered directly to it rather than welded to housing. Seals between flange and housing, and between connector and flange resistant to leaks, even after mechanical overloading and thermal shocking.

Single-Shell Tanks Leak Integrity Elements/ SX Farm Leak Causes and Locations - 12127

DOE Office of Scientific and Technical Information (OSTI.GOV)

Girardot, Crystal; Harlow, Don; Venetz, Theodore

2012-07-01

Washington River Protection Solutions, LLC (WRPS) developed an enhanced single-shell tank (SST) integrity project in 2009. An expert panel on SST integrity was created to provide recommendations supporting the development of the project. One primary recommendation was to expand the leak assessment reports (substitute report or LD-1) to include leak causes and locations. The recommendation has been included in the M-045-91F Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) as one of four targets relating to SST leak integrity. The 241-SX Farm (SX Farm) tanks with leak losses were addressed on an individual tank basis as part of LD-1.more » Currently, 8 out of 23 SSTs that have been reported to having a liner leak are located in SX Farm. This percentage was the highest compared to other tank farms which is why SX Farm was analyzed first. The SX Farm is comprised of fifteen SSTs built 1953-1954. The tanks are arranged in rows of three tanks each, forming a cascade. Each of the SX Farm tanks has a nominal 1-million-gal storage capacity. Of the fifteen tanks in SX Farm, an assessment reported leak losses for the following tanks: 241-SX-107, 241-SX-108, 241-SX-109, 241-SX- 111, 241-SX-112, 241-SX-113, 241-SX-114 and 241-SX-115. The method used to identify leak location consisted of reviewing in-tank and ex-tank leak detection information. This provided the basic data identifying where and when the first leaks were detected. In-tank leak detection consisted of liquid level measurement that can be augmented with photographs which can provide an indication of the vertical leak location on the sidewall. Ex-tank leak detection for the leaking tanks consisted of soil radiation data from laterals and dry-wells near the tank. The in-tank and ex-tank leak detection can provide an indication of the possible leak location radially around and under the tank. Potential leak causes were determined using in-tank and ex-tank information that is not directly related to leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching. (authors)« less

SINGLE-SHELL TANKS LEAK INTEGRITY ELEMENTS/SX FARM LEAK CAUSES AND LOCATIONS - 12127

DOE Office of Scientific and Technical Information (OSTI.GOV)

VENETZ TJ; WASHENFELDER D; JOHNSON J

2012-01-25

Washington River Protection Solutions, LLC (WRPS) developed an enhanced single-shell tank (SST) integrity project in 2009. An expert panel on SST integrity was created to provide recommendations supporting the development of the project. One primary recommendation was to expand the leak assessment reports (substitute report or LD-1) to include leak causes and locations. The recommendation has been included in the M-045-9IF Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) as one of four targets relating to SST leak integrity. The 241-SX Farm (SX Farm) tanks with leak losses were addressed on an individual tank basis as part of LD-1.more » Currently, 8 out of 23 SSTs that have been reported to having a liner leak are located in SX Farm. This percentage was the highest compared to other tank farms which is why SX Farm was analyzed first. The SX Farm is comprised of fifteen SSTs built 1953-1954. The tanks are arranged in rows of three tanks each, forming a cascade. Each of the SX Farm tanks has a nominal I-million-gal storage capacity. Of the fifteen tanks in SX Farm, an assessment reported leak losses for the following tanks: 241-SX-107, 241-SX-108, 241-SX-109, 241-SX-111, 241-SX-112, 241-SX-113, 241-SX-114 and 241-SX-115. The method used to identify leak location consisted of reviewing in-tank and ex-tank leak detection information. This provided the basic data identifying where and when the first leaks were detected. In-tank leak detection consisted of liquid level measurement that can be augmented with photographs which can provide an indication of the vertical leak location on the sidewall. Ex-tank leak detection for the leaking tanks consisted of soil radiation data from laterals and drywells near the tank. The in-tank and ex-tank leak detection can provide an indication of the possible leak location radially around and under the tank. Potential leak causes were determined using in-tank and ex-tank information that is not directly related to leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design - working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching.« less

Demonstration of rapid and sensitive module leak certification for space station freedom. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dietz, R.N.; Goodrich, R.W.

1991-03-01

A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 {plus_minus} 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 {plus_minus} 0.7, {minus}0.4 {plus_minus} 0.3, and 76 {plus_minus} 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone testmore » facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on {Delta}p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc. 13 refs.« less

Demonstration of rapid and sensitive module leak certification for space station freedom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dietz, R.N.; Goodrich, R.W.

1991-03-01

A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 {plus minus} 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 {plus minus} 0.7, {minus}0.4 {plus minus} 0.3, and 76 {plus minus} 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes formore » a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on {Delta}p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc. 13 refs.« less

Demonstration of rapid and sensitive module leak certification for Space Station Freedom

NASA Technical Reports Server (NTRS)

Dietz, R. N.; Goodrich, R. W.

1991-01-01

A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 (+ or -) 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 (+ or -) 0.7, -0.4 (+ or -) 0.3, and 76 (+ or -) 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on (Delta)p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc.

49 CFR 195.444 - CPM leak detection.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false CPM leak detection. 195.444 Section 195.444... PIPELINE Operation and Maintenance § 195.444 CPM leak detection. Each computational pipeline monitoring (CPM) leak detection system installed on a hazardous liquid pipeline transporting liquid in single...

Leakage detection in galvanized iron pipelines using ensemble empirical mode decomposition analysis

NASA Astrophysics Data System (ADS)

Amin, Makeen; Ghazali, M. Fairusham

2015-05-01

There are many numbers of possible approaches to detect leaks. Some leaks are simply noticeable when the liquids or water appears on the surface. However many leaks do not find their way to the surface and the existence has to be check by analysis of fluid flow in the pipeline. The first step is to determine the approximate position of leak. This can be done by isolate the sections of the mains in turn and noting which section causes a drop in the flow. Next approach is by using sensor to locate leaks. This approach are involves strain gauge pressure transducers and piezoelectric sensor. the occurrence of leaks and know its exact location in the pipeline by using specific method which are Acoustic leak detection method and transient method. The objective is to utilize the signal processing technique in order to analyse leaking in the pipeline. With this, an EEMD method will be applied as the analysis method to collect and analyse the data.

Mobile natural gas leak surveys indicate that two utilities have high false negative rates

NASA Astrophysics Data System (ADS)

von Fischer, J. C.; Brewer, P. E.; Chamberlain, S.; Gaylord, A.; von Fischer, J.

2016-12-01

In the distribution systems that carry natural gas to consumers, leaks need to be discovered for safety reasons and to reduce greenhouse gas emissions. However, few utilities have adopted newer laser-based technologies that have greater sensitivity and precision, and instead rely on "industry standard" equipment that is far less sensitive. In partnership with the Environmental Defense Fund and Google, we mapped natural gas leaks in the domains of two anonymous utilities (Utility "A" and "B") using high sensitivity Picarro methane analyzers in Google Street View Cars. Surprisingly, when we shared these results with utilities, their survey crews were unable to find most of the leaks that our survey indicated (84% in A and 80% in B). To investigate this phenomenon, our team visited a subset of the leaks in each utility domain (n=32 in A and n=30 in B), and worked alongside utility surveyors to search the leak indication area, using a Los Gatos Research ultraportable methane analyzer to pinpoint leak locations. We found evidence of natural gas leaks at 69% and 68% of the locations in Utilities A and B respectively where survey crews had found nothing. We describe this as a "false negative" rate for the utility because the utility survey falsely indicated that there was no leak at these locations. Of these false negatives, 7% (n=2 of 32 in A, n=2 of 30 in B) were determined to be Grade 1 leaks requiring immediate repair due to high safety risk. Instrument sensitivity appears to explain some of the false negative rates. In particular, use of some industry standard equipment appears to have created a false sense of confidence among utility surveyors that leaks were not present. However, there was also evidence of communication failures and that surveyors did not use optimal approaches in their search. Based on these findings, we suggest that: 1) mobile deployment of high-precision methane analyzers can help find more natural gas leaks, and 2) use of some hand-held survey instruments may lead to higher rates of false negatives in leak survey and 3) there may be room for improvement in leak survey methodologies.

A risk score to predict the incidence of prolonged air leak after video-assisted thoracoscopic lobectomy: An analysis from the European Society of Thoracic Surgeons database.

PubMed

Pompili, Cecilia; Falcoz, Pierre Emmanuel; Salati, Michele; Szanto, Zalan; Brunelli, Alessandro

2017-04-01

The study objective was to develop an aggregate risk score for predicting the occurrence of prolonged air leak after video-assisted thoracoscopic lobectomy from patients registered in the European Society of Thoracic Surgeons database. A total of 5069 patients who underwent video-assisted thoracoscopic lobectomy (July 2007 to August 2015) were analyzed. Exclusion criteria included sublobar resections or pneumonectomies, lung resection associated with chest wall or diaphragm resections, sleeve resections, and need for postoperative assisted mechanical ventilation. Prolonged air leak was defined as an air leak more than 5 days. Several baseline and surgical variables were tested for a possible association with prolonged air leak using univariable and logistic regression analyses, determined by bootstrap resampling. Predictors were proportionally weighed according to their regression estimates (assigning 1 point to the smallest coefficient). Prolonged air leak was observed in 504 patients (9.9%). Three variables were found associated with prolonged air leak after logistic regression: male gender (P < .0001, score = 1), forced expiratory volume in 1 second less than 80% (P < .0001, score = 1), and body mass index less than 18.5 kg/m 2 (P < .0001, score = 2). The aggregate prolonged air leak risk score was calculated for each patient by summing the individual scores assigned to each variable (range, 0-4). Patients were then grouped into 4 classes with an incremental risk of prolonged air leak (P < .0001): class A (score 0 points, 1493 patients) 6.3% with prolonged air leak, class B (score 1 point, 2240 patients) 10% with prolonged air leak, class C (score 2 points, 1219 patients) 13% with prolonged air leak, and class D (score >2 points, 117 patients) 25% with prolonged air leak. An aggregate risk score was created to stratify the incidence of prolonged air leak after video-assisted thoracoscopic lobectomy. The score can be used for patient counseling and to identify those patients who can benefit from additional intraoperative preventative measures. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Improved Portable Ultrasonic Leak Detectors

NASA Technical Reports Server (NTRS)

Youngquist, Robert C.; Moerk, John S.; Haskell, William D.; Cox, Robert B.; Polk, Jimmy D.; Strobel, James P.; Luaces, Frank

1995-01-01

Improved portable ultrasonic leak detector features three interchangeable ultrasonic-transducer modules, each suited for operation in unique noncontact or contact mode. One module equipped with ultrasound-collecting horn for use in scanning to detect leaks from distance; horn provides directional sensitivity pattern with sensitivity multiplied by factor of about 6 in forward direction. Another module similar, does not include horn; this module used for scanning close to suspected leak, where proximity of leak more than offsets loss of sensitivity occasioned by lack of horn. Third module designed to be pressed against leaking vessel; includes rugged stainless-steel shell. Improved detectors perform significantly better, smaller, more rugged, and greater sensitivity.

Identification of multiple leaks in pipeline: Linearized model, maximum likelihood, and super-resolution localization

NASA Astrophysics Data System (ADS)

Wang, Xun; Ghidaoui, Mohamed S.

2018-07-01

This paper considers the problem of identifying multiple leaks in a water-filled pipeline based on inverse transient wave theory. The analytical solution to this problem involves nonlinear interaction terms between the various leaks. This paper shows analytically and numerically that these nonlinear terms are of the order of the leak sizes to the power two and; thus, negligible. As a result of this simplification, a maximum likelihood (ML) scheme that identifies leak locations and leak sizes separately is formulated and tested. It is found that the ML estimation scheme is highly efficient and robust with respect to noise. In addition, the ML method is a super-resolution leak localization scheme because its resolvable leak distance (approximately 0.15λmin , where λmin is the minimum wavelength) is below the Nyquist-Shannon sampling theorem limit (0.5λmin). Moreover, the Cramér-Rao lower bound (CRLB) is derived and used to show the efficiency of the ML scheme estimates. The variance of the ML estimator approximates the CRLB proving that the ML scheme belongs to class of best unbiased estimator of leak localization methods.

Helium Mass Spectrometer Leak Detection: A Method to Quantify Total Measurement Uncertainty

NASA Technical Reports Server (NTRS)

Mather, Janice L.; Taylor, Shawn C.

2015-01-01

In applications where leak rates of components or systems are evaluated against a leak rate requirement, the uncertainty of the measured leak rate must be included in the reported result. However, in the helium mass spectrometer leak detection method, the sensitivity, or resolution, of the instrument is often the only component of the total measurement uncertainty noted when reporting results. To address this shortfall, a measurement uncertainty analysis method was developed that includes the leak detector unit's resolution, repeatability, hysteresis, and drift, along with the uncertainty associated with the calibration standard. In a step-wise process, the method identifies the bias and precision components of the calibration standard, the measurement correction factor (K-factor), and the leak detector unit. Together these individual contributions to error are combined and the total measurement uncertainty is determined using the root-sum-square method. It was found that the precision component contributes more to the total uncertainty than the bias component, but the bias component is not insignificant. For helium mass spectrometer leak rate tests where unit sensitivity alone is not enough, a thorough evaluation of the measurement uncertainty such as the one presented herein should be performed and reported along with the leak rate value.

Endoscopic Transmaxillary Transposition of Temporalis Flap for Recurrent Cerebrospinal Fluid Leak Closure.

PubMed

Thomas, Regi; Girishan, Shabari; Chacko, Ari George

2016-12-01

Objective  To describe the technique of endoscopic transmaxillary temporalis muscle flap transposition for the repair of a persistent postoperative sphenoidal cerebrospinal fluid leak. Design  The repair of a recurrent cerebrospinal fluid leak for a patient who had undergone endoscopic transsphenoidal excision of an invasive silent corticotroph Hardy C and Knosp Grade IV pituitary adenoma was undertaken. The patient had completed postoperative radiotherapy for the residual tumor and presented with cerebrospinal fluid leak, 1 year later. The initial two attempts to repair the cerebrospinal fluid leak with free grafts failed. Therefore, an endoscopic transmaxillary transposition of the temporalis muscle flap was attempted to stop the cerebrospinal fluid leak. Results  The endoscopic transmaxillary transposition of the vascularized temporalis muscle flap onto the cerebrospinal fluid leak repair site resulted in successful closure of the cerebrospinal fluid leak. Conclusion  Endoscopic transmaxillary transposition of the temporalis flap resulted in closure of recurrent cerebrospinal fluid leak in a patient with recurrent pituitary adenoma, who had undergone previous surgery and radiotherapy. This technique has advantages over the endoscopic transpterygoid transposition of the same flap and could be used as a complementary technique in selected patients.

Fiber optic distributed chemical sensor for the real time detection of hydrocarbon fuel leaks

NASA Astrophysics Data System (ADS)

Mendoza, Edgar; Kempen, C.; Esterkin, Yan; Sun, Sunjian

2015-09-01

With the increase worldwide demand for hydrocarbon fuels and the vast development of new fuel production and delivery infrastructure installations around the world, there is a growing need for reliable hydrocarbon fuel leak detection technologies to provide safety and reduce environmental risks. Hydrocarbon leaks (gas or liquid) pose an extreme danger and need to be detected very quickly to avoid potential disasters. Gas leaks have the greatest potential for causing damage due to the explosion risk from the dispersion of gas clouds. This paper describes progress towards the development of a fast response, high sensitivity, distributed fiber optic fuel leak detection (HySense™) system based on the use of an optical fiber that uses a hydrocarbon sensitive fluorescent coating to detect the presence of fuel leaks present in close proximity along the length of the sensor fiber. The HySense™ system operates in two modes, leak detection and leak localization, and will trigger an alarm within seconds of exposure contact. The fast and accurate response of the sensor provides reliable fluid leak detection for pipelines, storage tanks, airports, pumps, and valves to detect and minimize any potential catastrophic damage.

Preventing a Washout.

ERIC Educational Resources Information Center

Poindexter, Dave

1996-01-01

Offers ideas for locating a roof leak. Discusses why many leaks originate in the roof's base flashings and the importance of knowing the roof's material makeup. Advocates keeping a roof-leak history and gives advice on performing inspections to check for leaks. Discusses how to find small holes in roofs. (RJM)

Anastomotic leaks: what is the best diagnostic imaging study?

PubMed

Nicksa, G A; Dring, R V; Johnson, K H; Sardella, W V; Vignati, P V; Cohen, J L

2007-02-01

Postoperative anastomotic leaks are one of the most devastating consequences of colorectal surgery. Diagnostic imaging for upper gastrointestinal anastomotic leaks has been evaluated and reported on extensively. No study has compared the utility and effectiveness of CT scans and water-soluble enemas for the identification of postoperative lower gastrointestinal anastomotic leaks. The present study was designed to evaluate and compare these two common radiographic imaging modalities in detecting lower gastrointestinal anastomotic leaks. A retrospective chart review was performed that identified 36 patients during a seven-year period who underwent reoperative surgery for a lower gastrointestinal anastomotic leak. Patient's imaging studies were classified as positive if extravasation of contrast material was demonstrated. When negative, a study was retrospectively reviewed in an attempt to identify findings suggestive of an anastomotic leak. There were 36 patients identified with a postoperative lower gastrointestinal leak requiring surgical intervention. There were 28 of 36 patients (78 percent) re-explored on the basis of a radiologic study demonstrating an anastomotic leak. A total of 27 CT scans were performed, of which 4 (14.8 percent) were considered positive for an anastomotic leak. On review of the remaining negative CT scans, nine (33.3 percent) were considered descriptive positive with a large amount of fluid or air in the peritoneal cavity but without obvious extravasation of contrast. Eighteen patients were evaluated with a water-soluble enema and 15 (83.3 percent) demonstrated extravasation of contrast material. In the 26 patients with a distal anastomotic leak, 17 water-soluble enemas were performed, with 15 (88 percent) demonstrating a leak. In contrast, only 2 of 17 (12 percent) CT scans were positive in this group of patients (P < 0.001). There were ten patients who initially had a CT scan followed by a water-soluble enema. Of these patients, eight of nine (88 percent) initially had a negative CT scan but were considered to be clinically suspicious of having an anastomotic leak and subsequently had a leak demonstrated on a water-soluble enema. Early intervention in patients who develop an anastomotic leak can be shown to improve the ultimate outcome, especially with respect to mortality. It is usually necessary to obtain objective tests of anastomotic integrity because of the nonspecificity of clinical signs. Our study supported the superiority of water-soluble enema to CT imaging in patients in whom both modalities were used. This difference was most pronounced for distal anastomotic leaks, whereas no radiologic imaging study proved effective in evaluating proximal anastomoses.

Validation of Test Methods for Air Leak Rate Verification of Spaceflight Hardware

NASA Technical Reports Server (NTRS)

Oravec, Heather Ann; Daniels, Christopher C.; Mather, Janice L.

2017-01-01

As deep space exploration continues to be the goal of NASAs human spaceflight program, verification of the performance of spaceflight hardware becomes increasingly critical. Suitable test methods for verifying the leak rate of sealing systems are identified in program qualification testing requirements. One acceptable method for verifying the air leak rate of gas pressure seals is the tracer gas leak detector method. In this method, a tracer gas (commonly helium) leaks past the test seal and is transported to the leak detector where the leak rate is quantified. To predict the air leak rate, a conversion factor of helium-to-air is applied depending on the magnitude of the helium flow rate. The conversion factor is based on either the molecular mass ratio or the ratio of the dynamic viscosities. The current work was aimed at validating this approach for permeation-level leak rates using a series of tests with a silicone elastomer O-ring. An established pressure decay method with constant differential pressure was used to evaluate both the air and helium leak rates of the O-ring under similar temperature and pressure conditions. The results from the pressure decay tests showed, for the elastomer O-ring, that neither the molecular flow nor the viscous flow helium-to-air conversion factors were applicable. Leak rate tests were also performed using nitrogen and argon as the test gas. Molecular mass and viscosity based helium-to-test gas conversion factors were applied, but did not correctly predict the measured leak rates of either gas. To further this study, the effect of pressure boundary conditions was investigated. Often, pressure decay leak rate tests are performed at a differential pressure of 101.3 kPa with atmospheric pressure on the downstream side of the test seal. In space applications, the differential pressure is similar, but with vacuum as the downstream pressure. The same O-ring was tested at four unique differential pressures ranging from 34.5 to 137.9 kPa. Up to six combinations of upstream and downstream pressures for each differential pressure were compared. For a given differential pressure, the various combinations of upstream and downstream dry air pressures did not significantly affect the leak rate. As expected, the leak rate of the O-ring increased with increasing differential pressure. The results suggested that the current leak test pressure conditions, used to verify spacecraft sealing systems with elastomer seals, produce accurate values even though the boundary conditions do not model the space application.

Method and apparatus for continuous fluid leak monitoring and detection in analytical instruments and instrument systems

DOEpatents

Weitz, Karl K [Pasco, WA; Moore, Ronald J [West Richland, WA

2010-07-13

A method and device are disclosed that provide for detection of fluid leaks in analytical instruments and instrument systems. The leak detection device includes a collection tube, a fluid absorbing material, and a circuit that electrically couples to an indicator device. When assembled, the leak detection device detects and monitors for fluid leaks, providing a preselected response in conjunction with the indicator device when contacted by a fluid.

Experiences with leak rate calculations methods for LBB application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grebner, H.; Kastner, W.; Hoefler, A.

1997-04-01

In this paper, three leak rate computer programs for the application of leak before break analysis are described and compared. The programs are compared to each other and to results of an HDR Reactor experiment and two real crack cases. The programs analyzed are PIPELEAK, FLORA, and PICEP. Generally, the different leak rate models are in agreement. To obtain reasonable agreement between measured and calculated leak rates, it was necessary to also use data from detailed crack investigations.

Temporal variation of the leak pressure of uncuffed endotracheal tubes following pediatric intubation: an observational study.

PubMed

Patel, Shreya; Lalwani, Kirk; Koh, Jeffrey; Wu, Lei; Fu, Rongwei

2014-06-01

Uncuffed endotracheal tubes are still preferred over cuffed tubes in certain situations in pediatric anesthesia. Inaccurately sized uncuffed endotracheal tubes may lead to inadequate ventilation or tracheal mucosal damage during anesthesia. Endotracheal tube size in children is usually assessed by measuring the audible leak pressure; if the fit of the tube and the leak pressure decrease significantly with time, reintubation during surgery as a result of inability to ventilate effectively may be challenging, and could lead to patient morbidity. There is no evidence to indicate whether leak pressure increases or decreases with time following endotracheal intubation with uncuffed tubes in children. We measured leak pressure for 30 min following tracheal intubation in 46 ASA I children age 0-7 years after excluding factors known to modify leak pressure. The largest mean change in leak pressure occurred between time points 0 and 15 min, an increase of 3.5 cmH2O. Endotracheal tube size and type of procedure were associated with the leak pressure. In the final linear mixed model, there were no statistically significant variations in leak pressure over time (P = 0.129) in this group of children. We did not identify a consistent change in leak pressure within 30 min following tracheal intubation with uncuffed endotracheal tubes in this group of children.

Recent advances in the treatment of air leaks.

PubMed

Cerfolio, Robert James

2005-07-01

Alveolar-pleural fistulas (air leaks) are an extremely common clinical problem and remain the most common complication after elective pulmonary resection and video-assisted procedures. The decision making process used to manage air leaks and chest tubes that control them has been, until very recently, based on opinions and training preferences as opposed to facts derived from randomized clinical trials. Recently, several prospective randomized trials have studied air leaks. An objective, reproducible classification system has also been designed and clinically validated to help study air leaks. This system and these studies have shown that water seal is superior to wall suction to help stop most leaks. Even in patients with a pneumothorax and an air leak, water seal is safe and best; however, if a patient has a large leak (greater than an expiratory 3 on the classification system) or experiences subcutaneous emphysema or an expanding pneumothorax that causes hypoxia, then some suction (-10 cm of water) should be applied to the chest tubes. Air leaks were a poorly understood yet extremely common clinical problem that had never been scientifically studied. Over the past 5 years, prospective randomized studies have shown that water seal is the best setting for chest tubes and that a pneumothorax is not a contraindication to leaving tubes on seal. Further studies are needed to investigate the ideal management of alveolar-pleural fistulas (air leaks) in different clinical scenarios besides those that occur postoperatively.

The Diagnostic Value of Routine Contrast Esophagram in Anastomotic Leaks After Esophagectomy.

PubMed

Hu, Zhongwu; Wang, Xiaowe; An, Xush; Li, Wenjin; Feng, Yun; You, Zhenbing

2017-08-01

Routine contrast esophagram has been shown to be increasingly limited in diagnosing anastomotic leaks after esophagectomy. Patients undergoing esophagectomy from 2013 to 2014 at Huai'an First Peoples' Hospital were identified. We retrospectively analyzed patients who underwent routine contrast esophagram on postoperative day 7 (range 6-10) to preclude anastomotic leaks after esophagectomy. In 846 patients who underwent esophagectomy, a cervical anastomosis was performed in 286 patients and an intrathoracic anastomosis in 560 patients. There were 57 (6.73%) cases with anastomotic leaks, including cervical leaks in 36 and intrathoracic leaks in 21 patients. In the cervical anastomotic leak patients, 13 were diagnosed by early local clinical symptoms and 23 underwent routine contrast esophagram. There were 7 (30.4%) true-positive, 11 (47.8%) false-negative, and five (21.8%) equivocal cases. In the intrathoracic anastomotic leak patients, four (19%) were diagnosed by clinical symptoms, 16 (76.2%) were true positives, and one (4.8%) was a false negative. Aspiration occurred in five patients with cervical anastomoses and in eight patients with intrathoracic anastomoses; aspiration pneumonitis did not occur in these cases. Gastrografin and barium are safe contrast agents to use in post-esophagectomy contrast esophagram. Because of the low sensitivity in detecting cervical anastomotic leaks, routine contrast esophagram is not advised. For patients with intrathoracic anastomoses, it is still an effective method for detecting anastomotic leaks.

Lymphangiography in the Diagnosis and Localization of Various Chyle Leaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deso, Steve; Ludwig, Benjamin; Kabutey, Nii-Kabu

2012-02-15

Purpose: Chyle leaks are rare entities infrequently encountered by most physicians. However, large centers providing advanced surgical care are inevitably confronted with chyle leaks as a complication of surgery, an extension of disease, or as a primary disorder. Regardless of the etiology, proper diagnosis and localization are paramount in the management of any chyle leak. Materials and Methods: Here we present 16 patients with 17 chyle leaks (5 chyluria, 8 chylothorax, and 4 chylous ascites) who underwent bipedal lymphangiography (LAG) and postprocedure computed tomography (CT) imaging. Results: In each case, the source of the chyle leak was identified and properlymore » localized to guide further treatment. Of the 16 patients who underwent LAG and postprocedure CT imaging, the initial LAG alone provided the diagnosis and localized the chyle leak in 4 patients (25%); the postprocedure CT imaging provided the diagnosis and localized the chyle leak in 6 patients (37.5%); and the two modalities were equal in the diagnosing and localizing the chyle leak in the remaining 6 patients (37.5%)ConclusionThese cases highlight the unparalleled abilities of LAG and the added benefit of post-LAG CT imaging in the diagnosis and fine anatomic localization of chyle leaks. In addition, these cases demonstrate the retained utility of LAG in these investigations despite the development of alternative tests involving CT, magnetic resonance imaging, and nuclear medicine imaging.« less

Technical factors associated with anastomotic leak after Roux-en-Y gastric bypass.

PubMed

Smith, Mark D; Adeniji, Abidemi; Wahed, Abdus S; Patterson, Emma; Chapman, William; Courcoulas, Anita P; Dakin, Gregory; Flum, David; McCloskey, Carol; Mitchell, James E; Pomp, Alfons; Staten, Myrlene; Wolfe, Bruce

2015-01-01

Anastomotic leak is one of the most serious complications after Roux-en-Y gastric bypass (RYGB). Our objective was to examine the relationship between technical factors and incidence of clinically relevant anastomotic leak after RYGB in longitudinal assessment of bariatric surgery (LABS). The setting of the study was 11 bariatric centers in the United States, university, and private practice. Patient characteristics, technical factors of surgery, and postoperative outcomes were assessed by trained researchers using standardized protocols. Correlation of surgical factors of patients undergoing RYGB (n = 4444) with the incidence of postoperative anastomotic leak was assessed by univariate χ(2) analysis. Forty-four participants (1.0%, 95% CI .7%-1.3%) experienced a clinically relevant anastomotic leak. Of these, 39 (89%) underwent abdominal reoperation and 3 (7%) died. Technical factors associated with anastomotic leak were open surgery (P<.0001), revision surgery (P<.0001), and use of an abdominal drain (P = .02). Provocative leak testing, method of gastrojejunostomy, and use of fibrin sealant were not associated with anastomotic leak. Anastomotic leak after RYGB was rare (1.0%). Most cases required reintervention; however, the majority (93%) recovered from this event. Open surgery, revision surgery, and routine drain placement were associated with increased leak rate. Some of these findings may be due to differences in preoperative patient risk. Copyright © 2015 American Society for Metabolic and Bariatric Surgery. All rights reserved.

Paravalvular Leak in Structural Heart Disease.

PubMed

Goel, Kashish; Eleid, Mackram F

2018-03-06

This review will summarize the growing importance of diagnosing and managing paravalvular leak associated with surgical and transcatheter valves. The burden of paravalvular leak is increasing; however, advanced imaging techniques and high degree of clinical suspicion are required for diagnosis and management. The latest data from pivotal clinical trials in the field of transcatheter aortic valve replacement suggest that any paravalvular leak greater than mild was associated with worse clinical outcomes. Percutaneous techniques for paravalvular leak closure are now the preferred approach, and surgical repair is reserved for contraindications and unsuccessful procedures. Recent data from studies evaluating paravalvular leak closure outcomes report a greater than 90% success rate with a significant improvement in patient symptoms. Paravalvular leak is a growing problem in the structural heart disease arena. Percutaneous closure is successful in more than 90% of the procedures with a low complication rate.

Superfluid helium leak sealant study

NASA Technical Reports Server (NTRS)

Vorreiter, J. W.

1981-01-01

Twenty-one leak specimens were fabricated in the ends of stainless steel and aluminum tubes. Eighteen of these tubes were coated with a copolymer material to seal the leak. The other three specimens were left uncoated and served as control specimens. All 21 tubes were cold shocked in liquid helium 50 times and then the leak rate was measured while the tubes were submerged in superfluid helium at 1.7 K. During the cold shocks two of the coated specimens were mechanically damaged and eliminated from the test program. Of the remaining 16 coated specimens one suffered a total coating failure and resulting high leak rate. Another three of the coated specimens suffered partial coating failures. The leak rates of the uncoated specimens were also measured and reported. The significance of various leak rates is discussed in view of the infrared astronomical satellite (IRAS) Dewar performance.

A multicenter study of routine versus selective intraoperative leak testing for sleeve gastrectomy.

PubMed

Bingham, Jason; Kaufman, Jedediah; Hata, Kai; Dickerson, James; Beekley, Alec; Wisbach, Gordon; Swann, Jacob; Ahnfeldt, Eric; Hawkins, Devon; Choi, Yong; Lim, Robert; Martin, Matthew

2017-09-01

Staple line leaks after sleeve gastrectomy are dreaded complications. Many surgeons routinely perform an intraoperative leak test (IOLT) despite little evidence to validate the reliability, clinical benefit, and safety of this procedure. To determine the efficacy of IOLT and if routine use has any benefit over selective use. Eight teaching hospitals, including private, university, and military facilities. A multicenter, retrospective analysis over a 5-year period. The efficacy of the IOLT for identifying unsuspected staple line defects and for predicting postoperative leaks was evaluated. An anonymous survey was also collected reflecting surgeons' practices and beliefs regarding IOLT. From January 2010 through December 2014, 4284 patients underwent sleeve gastrectomy. Of these, 37 patients (.9%) developed a postoperative leak, and 2376 patients (55%) received an IOLT. Only 2 patients (0.08%) had a positive finding. Subsequently, 21 patients with a negative IOLT developed a leak. IOLT demonstrated a sensitivity of only 8.7%. There was a nonsignificant trend toward increased leak rates when an IOLT was performed versus when IOLT was not performed. Leak rates were not statistically different between centers that routinely perform IOLT versus those that selectively perform IOLT. Routine IOLT had very poor sensitivity and was negative in 91% of patients who later developed postoperative leaks. The use of IOLT was not associated with a decrease in the incidence of postoperative leaks, and routine IOLT had no benefit over selective leak testing. IOLT should not be used as a quality indicator or "best practice" for bariatric surgery. Published by Elsevier Inc.

Assessing Surgeon Behavior Change after Anastomotic Leak in Colorectal Surgery

PubMed Central

Simianu, Vlad V.; Basu, Anirban; Alfonso-Cristancho, Rafael; Thirlby, Richard C.; Flaxman, Abraham D.; Flum, David R.

2016-01-01

Background Recency effect suggests that people disproportionately value events from the immediate past when making decisions, but the extent of this impact on surgeons’ decisions is unknown. This study evaluates for recency effect in surgeons by examining use of preventative leak testing before and after colorectal operations with anastomotic leaks. Materials and Methods Prospective cohort of adult patients (≥18 years) undergoing elective colorectal operations at Washington State hospitals participating in the Surgical Care and Outcomes Assessment Program (2006–2013). The main outcome measure was surgeons’ change in leak testing from 6 months before to 6 months after an anastomotic leak occurred. Results Across 4,854 elective colorectal operations performed by 282 surgeons at 44 hospitals, there was a leak rate of 2.6% (n=124). The 40 leaks (32%) in which the anastomosis was not tested occurred across 25 surgeons. While the ability to detect an overall difference in use of leak testing was limited by small sample size, 9 (36%) of 25 surgeons increased their leak testing by 5 percent points or more after leaks in cases where the anastomosis was not tested. Surgeons who increased their leak testing more frequently performed operations for diverticulitis (45% vs 33%), more frequently began their cases laparoscopically (65% vs 37%), and had longer mean operative times (195±99 vs 148±87 minutes), all p<0.001. Conclusions Recency effect was demonstrated by only one-third of eligible surgeons. Understanding the extent to which clinical decisions may be influenced by recency effect may be important in crafting quality improvement initiatives that require clinician behavior change. PMID:27664886

40 CFR 63.11583 - What are my monitoring requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... preparation operation are in target HAP service: (a) Operate a bag leak detection system with alarm that will alert operators of a leak in the control device filter material. If a bag leak detection system with... install, calibrate, operate, and maintain each bag leak detection system and alarm according to...

40 CFR 63.424 - Standards: Equipment leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards: Equipment leaks. 63.424....424 Standards: Equipment leaks. (a) Each owner or operator of a bulk gasoline terminal or pipeline breakout station subject to the provisions of this subpart shall perform a monthly leak inspection of all...

PORTABLE IMAGING DEVICES FOR INDUSTRIAL LEAK DETECTION AT PETROLEUM REFINERIES AND CHEMICAL PLANTS

EPA Science Inventory

Undiscovered gas leaks, or fugitive emissions, in chemical plants and refinery operations can impact regional air quality as well as being a public health problem. Surveying a facility for potential gas leaks can be a daunting task. Industrial Leak Detection and Repair (LDAR) pro...

40 CFR 63.986 - Nonflare control devices used for equipment leaks only.

Code of Federal Regulations, 2010 CFR

2010-07-01

... equipment leaks only. 63.986 Section 63.986 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... leaks only. (a) Equipment and operating requirements. (1) Owners or operators using a nonflare control device to meet the applicable requirements of a referencing subpart for equipment leaks shall meet the...

40 CFR 63.691 - Standards: Equipment leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Standards: Equipment leaks. 63.691....691 Standards: Equipment leaks. (a) The provisions of this section apply to the control of air emissions from equipment leaks for which § 63.683(d) references the use of this section for such air...

Hanford Double-Shell Tank AY-102 Radioactive Waste Leak Investigation Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

Washenfelder, Dennis J.

2015-02-03

The presentation outline is: Briefly review leak integrity status of tank AY-102 and current leak behavior; Summarize recent initiatives to understand leak mechanism and to verify integrity of remaining waste confinement structures; describe planned waste recovery activities; and, introduce other papers on tank AY-102 topics.

Conceptual apparatus for detecting leaks of nonconductive liquids

NASA Technical Reports Server (NTRS)

Walsh, G. D.

1968-01-01

Apparatus detects leaks at joints in lines carrying electrically nonconductive liquids. The proposed apparatus could include a panel that would give a visual or audible indication of a leak /to permit manual shutdown/ and/or an electromechanical actuator that would automatically cut off the flow when a leak occurs.

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2013 CFR

2013-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2012 CFR

2012-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2011 CFR

2011-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

40 CFR 63.1005 - Leak repair.

Code of Federal Regulations, 2014 CFR

2014-07-01

... lubricant into the lubricated packing. (b) Leak identification removal—(1) Valves in gas/vapor and light liquid service. The leak identification on a valve in gas/vapor or light liquid service may be removed... monitoring. The leak identification on a connector in gas/vapor or light liquid service may be removed after...

Sensitivities of Soap Solutions in Leak Detection

NASA Technical Reports Server (NTRS)

Stuck, D.; Lam, D. Q.; Daniels, C.

1985-01-01

Document describes method for determining minimum leak rate to which soap-solution leak detectors sensitive. Bubbles formed at smaller leak rates than previously assumed. In addition to presenting test results, document discusses effects of joint-flange configurations, properties of soap solutions, and correlation of test results with earlier data.

Development And Testing Of The Inertial Electrostatic Confinement Diffusion Thruster

NASA Technical Reports Server (NTRS)

Becnel, Mark D.; Polzin, Kurt A.

2013-01-01

The Inertial Electrostatic Confinement (IEC) diffusion thruster is an experiment in active development that takes advantage of physical phenomenon that occurs during operation of an IEC device. The IEC device has been proposed as a fusion reactor design that relies on traditional electrostatic ion acceleration and is typically arranged in a spherical geometry. The design incorporates two radially-symmetric spherical electrodes. Often the inner electrode utilizes a grid of wire shaped in a sphere with a radius 15 to 50 percent of the radius of the outer electrode. The inner electrode traditionally has 90 percent or more transparency to allow particles (ions) to pass to the center of the spheres and collide/recombine in the dense plasma core at r=0. When operating the IEC, an unsteady plasma leak is typically observed passing out one of the gaps in the lattice grid of the inner electrode. The IED diffusion thruster is based upon the idea that this plasma leak can be used for propulsive purposes. The IEC diffusion thruster utilizes the radial symmetry found in the IEC device. A cylindrical configuration is employed here as it will produce a dense core of plasma the length of the cylindrical grid while promoting the plasma leak to exhaust through an electromagnetic nozzle at one end of the apparatus. A proof-of-concept IEC diffusion thruster is operational and under testing using argon as propellant (Figure 1).

Wafer-level hermetic vacuum packaging by bonding with a copper-tin thin film sealing ring

NASA Astrophysics Data System (ADS)

Akashi, Teruhisa; Funabashi, Hirofumi; Takagi, Hideki; Omura, Yoshiteru; Hata, Yoshiyuki

2018-04-01

A wafer-level hermetic vacuum packaging technology intended for use with MEMS devices was developed based on a copper-tin (CuSn) thin film sealing ring. To allow hermetic packaging, the shear strength of the CuSn thin film bond was improved by optimizing the pretreatment conditions. As a result, an average shear strength of 72.3 MPa was obtained and a cavity that had been hermetically sealed using wafer-level packaging (WLP) maintained its vacuum for 1.84 years. The total pressures in the cavities and the partial pressures of residual gases were directly determined with an ultra-low outgassing residual gas analyzer (RGA) system. Hermeticity was evaluated based on helium leak rates, which were calculated from helium pressures determined with the RGA system. The resulting data showed that a vacuum cavity following 1.84 years storage had a total pressure of 83.1 Pa, contained argon as the main residual gas and exhibited a helium leak rate as low as 1.67  ×  10-17 Pa · m3 s-1, corresponding to an air leak rate of 6.19  ×  10-18 Pa · m3 s-1. The RGA data demonstrate that WLP using a CuSn thin film sealing ring permits ultra-high hermeticity in conjunction with long-term vacuum packaging that is applicable to MEMS devices.

Intracochlear drug injections through the round window membrane: Measures to improve drug retention

PubMed Central

Plontke, Stefan K.; Hartsock, Jared J.; Gill, Ruth M.; Salt, Alec N.

2016-01-01

The goal of this study was to develop appropriate methodology to apply drugs quantitatively to perilymph of the ear. Intratympanic applications of drugs to the inner ear often result in variable drug levels in perilymph and can only be used for molecules that readily permeate the round window (RW) membrane. Direct intracochlear and intralabyrinthine application procedures for drugs, genes or cell-based therapies by-pass the tight boundaries at the round window, oval window, otic capsule and the blood-labyrinth barrier. However, perforations can release inner ear pressure, allowing cerebrospinal fluid to enter through the cochlear aqueduct, displacing the injected drug solution into the middle ear. Two markers, fluorescein or fluorescein isothiocyanate (FITC)-labeled dextran, were used to quantify how much of an injected substance was retained in cochlear perilymph following an intracochlear injection. We evaluated whether procedures to mitigate fluid leaks improved marker retention in perilymph. Almost all procedures to reduce volume efflux, including the use of gel for internal sealing and glue for external sealing of the injection site, resulted in improved retention of the marker in perilymph. Adhesive on the RW membrane effectively prevented leaks but also influenced fluid exchange between CSF and perilymph. We conclude that drugs can be delivered to the ear in a consistent, quantitative manner using intracochlear injections if care is taken to control the fluid leaks that result from cochlear perforation. PMID:26905306

Ultrasonic Phased Array Evaluation of Control Rod Drive Mechanism (CRDM) Nozzle Interference Fit and Weld Region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cinson, Anthony D.; Crawford, Susan L.; MacFarlan, Paul J.

2011-07-31

Ultrasonic phased array data were collected on a removed-from-service CRDM nozzle specimen to assess a previously reported leak path. First a mock-up CRDM specimen was evaluated that contained two 0.076-mm (3.0-mil) interference fit regions formed from an actual Inconel CRDM tube and two 152.4-mm (6.0-in.) thick carbon steel blocks. One interference fit region has a series of precision crafted electric discharge machining (EDM) notches at various lengths, widths, depths, and spatial separations for establishing probe sensitivity, resolution and calibration. The other interference fit has zones of boric acid (crystal form) spaced periodically between the tube and block to represent anmore » actively leaking CRDM nozzle assembly in the field. Ultrasonic phased-array evaluations were conducted using an immersion 8-element annular 5.0-MHz probe from the tube inner diameter (ID). A variety of focal laws were employed to evaluate the interference fit regions and J grove weld, where applicable. Responses from the mock-up specimen were evaluated to determine detection limits and characterization ability as well as contrast the ultrasonic response differences with the presence of boric acid in the fit region. Nozzle 63, from the North Anna Unit-2 nuclear power plant, was evaluated to assess leakage path(s) and was destructively dismantled to allow a visual verification of the leak path(s).« less

Management of Anterior Skull Base Defect Depending on Its Size and Location

PubMed Central

Bernal-Sprekelsen, Manuel; Rioja, Elena; Enseñat, Joaquim; Enriquez, Karla; Viscovich, Liza; Agredo-Lemos, Freddy Enrique; Alobid, Isam

2014-01-01

Introduction. We present our experience in the reconstruction of these leaks depending on their size and location. Material and Methods. Fifty-four patients who underwent advanced skull base surgery (large defects, >20 mm) and 62 patients with CSF leaks of different origin (small, 2–10 mm, and midsize, 11–20 mm, defects) were included in the retrospective study. Large defects were reconstructed with a nasoseptal pedicled flap positioned on fat and fascia lata. In small and midsized leaks. Fascia lata in an underlay position was used for its reconstruction covered with mucoperiosteum of either the middle or the inferior turbinate. Results. The most frequent etiology for small and midsized defects was spontaneous (48.4%), followed by trauma (24.2%), iatrogenic (5%). The success rate after the first surgical reconstruction was 91% and 98% in large skull base defects and small/midsized, respectively. Rescue surgery achieved 100%. Conclusions. Endoscopic surgery for any type of skull base defect is the gold standard. The size of the defects does not seem to play a significant role in the success rate. Fascia lata and mucoperiosteum of the turbinate allow a two-layer reconstruction of small and midsized defects. For larger skull base defects, a combination of fat, fascia lata, and nasoseptal pedicled flaps provides a successful reconstruction. PMID:24895567

Preliminary delineation and description of the regional aquifers of Tennessee : the Central Basin system

USGS Publications Warehouse

Brahana, J.V.; Bradley, M.W.

1986-01-01

A sand and gravel aquifer about 65 feet thick underlies Wurtsmith Air Force Base in northeastern lower Michigan. The water table ranges in depth from 10 feet to 25 feet below land surface. Mathematical models indicate that ground-water flow ranges from 0.8 feet per day in the eastern part of the Base to 0.3 feet per day in the western part. Trichlorethylene leaked from a buried storage tank in the southeastern part of the Base and moved northeastward in a plume, contaminating Base water-supply wells. Concentrations exceed 1,000 micrograms per liter in the most highly contaminated part of the plume. Purge pumping removed some of the trichloroethylene and seems to have arrested its eastward movement. Pumping of additional purge wells could increase the rate of removal. (USGS)

Numerical Modeling, Thermomechanical Testing, and NDE Procedures for Prediction of Microcracking Induced Permeability of Cryogenic Composites

NASA Technical Reports Server (NTRS)

Noh, Jae; Whitcomb, John; Oh, Bongtaek; Lagoudas, Dimitris; Maslov, Konstatin; Ganpatyre, Atul; Kinra, Vikram

2003-01-01

Reusable Space Vehicles will include light cryogenic composite fuel tanks that must not leak excessively even after multiple launches. Damage in cryogenic composite fuel tanks induced during manufacturing and advanced by thermomechanical cycling can accelerate leakage of the propellant. Whether the leakage exceeds tolerable levels depends on many factors, including pressure gradients, microcrack density, other damage such as delamination, connectivity of the cracks, residual stresses from manufacture, service-induced stresses from thermal and mechanical loads, and composite lay-up. Although it is critical to experimentally characterize permeability during various thermal and mechanical load histories, optimal design depends on having analytical models that can predict the effect of various parameters on performance. Our broad goal is to develop such models that are experimentally validated by destructive and non-destructive evaluation means.

Infrared Camera System for Visualization of IR-Absorbing Gas Leaks

NASA Technical Reports Server (NTRS)

Youngquist, Robert; Immer, Christopher; Cox, Robert

2010-01-01

Leak detection and location remain a common problem in NASA and industry, where gas leaks can create hazardous conditions if not quickly detected and corrected. In order to help rectify this problem, this design equips an infrared (IR) camera with the means to make gas leaks of IR-absorbing gases more visible for leak detection and location. By comparing the output of two IR cameras (or two pictures from the same camera under essentially identical conditions and very closely spaced in time) on a pixel-by-pixel basis, one can cancel out all but the desired variations that correspond to the IR absorption of the gas of interest. This can be simply done by absorbing the IR lines that correspond to the gas of interest from the radiation received by one of the cameras by the intervention of a filter that removes the particular wavelength of interest from the "reference" picture. This can be done most sensitively with a gas filter (filled with the gas of interest) placed in front of the IR detector array, or (less sensitively) by use of a suitable line filter in the same location. This arrangement would then be balanced against the unfiltered "measurement" picture, which will have variations from IR absorption from the gas of interest. By suitable processing of the signals from each pixel in the two IR pictures, the user can display only the differences in the signals. Either a difference or a ratio output of the two signals is feasible. From a gas concentration viewpoint, the ratio could be processed to show the column depth of the gas leak. If a variation in the background IR light intensity is present in the field of view, then large changes in the difference signal will occur for the same gas column concentration between the background and the camera. By ratioing the outputs, the same signal ratio is obtained for both high- and low-background signals, even though the low-signal areas may have greater noise content due to their smaller signal strength. Thus, one embodiment would use a ratioed output signal to better represent the gas column concentration. An alternative approach uses a simpler multiplication of the filtered signal to make the filtered signal equal to the unfiltered signal at most locations, followed by a subtraction to remove all but the wavelength-specific absorption in the unfiltered sample. This signal processing can also reveal the net difference signal representing the leaking gas absorption, and allow rapid leak location, but signal intensity would not relate solely to gas absorption, as raw signal intensity would also affect the displayed signal. A second design choice is whether to use one camera with two images closely spaced in time, or two cameras with essentially the same view and time. The figure shows the two-camera version. This choice involves many tradeoffs that are not apparent until some detailed testing is done. In short, the tradeoffs involve the temporal changes in the field picture versus the pixel sensitivity curves and frame alignment differences with two cameras, and which system would lead to the smaller variations from the uncontrolled variables.

Fluid leak indicator

NASA Technical Reports Server (NTRS)

Anderson, G. E.; Loo, S. (Inventor)

1985-01-01

A fluid leak indicator for detecting and indicating leaks in visually inaccessible fluid tubing joints, such as those obstructed by insulation includes a bag system and a wicking system surrounding or wrapping the joints under the visual obstructing material. Leaking fluid is collected in the bag or on the wicking material where it is conducted along the wicking material to a visily accessible capturing transparent indicator bulb for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb.

High sensitivity leak detection method and apparatus

DOEpatents

Myneni, Ganapatic R.

1994-01-01

An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1.times.10.sup.-18 atm cc sec.sup.-1.

High sensitivity leak detection method and apparatus

DOEpatents

Myneni, G.R.

1994-09-06

An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1 [times] 10[sup [minus]18] atm cc sec[sup [minus]1]. 2 figs.

Small-target leak detection for a closed vessel via infrared image sequences

NASA Astrophysics Data System (ADS)

Zhao, Ling; Yang, Hongjiu

2017-03-01

This paper focus on a leak diagnosis and localization method based on infrared image sequences. Some problems on high probability of false warning and negative affect for marginal information are solved by leak detection. An experimental model is established for leak diagnosis and localization on infrared image sequences. The differential background prediction is presented to eliminate the negative affect of marginal information on test vessel based on a kernel regression method. A pipeline filter based on layering voting is designed to reduce probability of leak point false warning. A synthesize leak diagnosis and localization algorithm is proposed based on infrared image sequences. The effectiveness and potential are shown for developed techniques through experimental results.

SURVEY ON PREVACUUM HIGH-PRESSURE STEAM STERILIZERS.

PubMed

DARMADY, E M; DREWETT, S E; HUGHES, K E

1964-03-01

None of the 10 prevacuum high-pressure sterilizers of different makes tested was able to produce and maintain the conditions advocated by the Medical Research Council working party on high-pressure steam sterilizers (1959) or by Knox and Penikett (1958) with the result that steam did not penetrate adequately the single challenge load and it was not sterilized. The sterilization of ;group drums' of various sizes and contents was erratic and tended to give operators a false sense of security. An alarming number of minor engineering faults were present in seven out of 10 machines tested and they require very much more skilled maintenance than is being given at the moment. The possibility of centralizing sterilizers to central sterile supply departments and placing them under the care of a regional engineer cannot be too highly recommended. The presence of undetected ;leaks' and a failure to draw a prevacuum of 20 mm. even with a steam burst interferes with sterilization of a challenge load. A leak test should be performed twice daily and should not exceed more than 1 mm. in one minute at 20 mm. absolute. The centre of the load should be monitored by crossed tapes or Brownes tubes in each sterilizing cycle. Although the challenge load was sterilized when the chamber was filled to capacity, a more reliable cycle consisting of a double prevacuum of 20 mm. or more with intermediate steam burst to 10 lb. ensured the sterilizing of a single challenge load, which could be adequately controlled by the chamber drain temperature.

Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

NASA Technical Reports Server (NTRS)

Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

2015-01-01

The design and test results for two types of pulsed gas valves are presented. The valves, a piezo valve and a solenoid actuated valve, must have exceedingly long lifetime to support gas-fed pulsed electric thruster operation for missions of interest. The performance of both valves was tested, with both demonstrating the capability to throttle the gas flow rate while maintaining low leakage levels below 10(exp -3) sccs of He at the beginning of valve lifetime. The piezo valve varies the flow rate by changing the amount that the valve is open, which is a function of applied voltage. This valve demonstrated continuous throttlability from 0-10 mL/s, with opening and closing times of 100 microsecond or less. The solenoid actuated valve flow rate changes as a function of the inlet gas pressure, with demonstrated flow rates in these tests from 2.7-11 mL per second. The valve response time is slower than the piezo valve, opening in 1-2 ms and closing in several ms. The solenoid actuated valve was tested to one million cycles, with the valve performance remaining relatively unchanged throughout the test. Galling of the sliding plunger caused the valve to bind and fail just after one million cycles, but at this point in the test the valve sealing surface leak rate still appeared to be well below the maximum target leak rake of 1×10(exp -3) sccs of He.

Distributed wireless sensing for methane leak detection technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, Levente; van Kesse, Theodor

Large scale environmental monitoring requires dynamic optimization of data transmission, power management, and distribution of the computational load. In this work, we demonstrate the use of a wireless sensor network for detection of chemical leaks on gas oil well pads. The sensor network consist of chemi-resistive and wind sensors and aggregates all the data and transmits it to the cloud for further analytics processing. The sensor network data is integrated with an inversion model to identify leak location and quantify leak rates. We characterize the sensitivity and accuracy of such system under multiple well controlled methane release experiments. It ismore » demonstrated that even 1 hour measurement with 10 sensors localizes leaks within 1 m and determines leak rate with an accuracy of 40%. This integrated sensing and analytics solution is currently refined to be a robust system for long term remote monitoring of methane leaks, generation of alarms, and tracking regulatory compliance.« less

Distributed wireless sensing for fugitive methane leak detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, Levente J.; van Kessel, Theodore; Nair, Dhruv

Large scale environmental monitoring requires dynamic optimization of data transmission, power management, and distribution of the computational load. In this work, we demonstrate the use of a wireless sensor network for detection of chemical leaks on gas oil well pads. The sensor network consist of chemi-resistive and wind sensors and aggregates all the data and transmits it to the cloud for further analytics processing. The sensor network data is integrated with an inversion model to identify leak location and quantify leak rates. We characterize the sensitivity and accuracy of such system under multiple well controlled methane release experiments. It ismore » demonstrated that even 1 hour measurement with 10 sensors localizes leaks within 1 m and determines leak rate with an accuracy of 40%. This integrated sensing and analytics solution is currently refined to be a robust system for long term remote monitoring of methane leaks, generation of alarms, and tracking regulatory compliance.« less

Distributed wireless sensing for fugitive methane leak detection

DOE PAGES

Klein, Levente J.; van Kessel, Theodore; Nair, Dhruv; ...

2017-12-11

Large scale environmental monitoring requires dynamic optimization of data transmission, power management, and distribution of the computational load. In this work, we demonstrate the use of a wireless sensor network for detection of chemical leaks on gas oil well pads. The sensor network consist of chemi-resistive and wind sensors and aggregates all the data and transmits it to the cloud for further analytics processing. The sensor network data is integrated with an inversion model to identify leak location and quantify leak rates. We characterize the sensitivity and accuracy of such system under multiple well controlled methane release experiments. It ismore » demonstrated that even 1 hour measurement with 10 sensors localizes leaks within 1 m and determines leak rate with an accuracy of 40%. This integrated sensing and analytics solution is currently refined to be a robust system for long term remote monitoring of methane leaks, generation of alarms, and tracking regulatory compliance.« less

Sensitivity of MRI of the spine compared with CT myelography in orthostatic headache with CSF leak.

PubMed

Starling, Amaal; Hernandez, Fatima; Hoxworth, Joseph M; Trentman, Terrence; Halker, Rashmi; Vargas, Bert B; Hastriter, Eric; Dodick, David

2013-11-12

To investigate the sensitivity of MRI of the spine compared with CT myelography (CTM) in detecting CSF leaks. Between July 1998 and October 2010, 12 patients with orthostatic headache and a CTM-confirmed spinal CSF leak underwent an MRI of the spine with and without contrast. Using CTM as the gold standard, we retrospectively investigated the sensitivity of spinal MRI in detecting a CSF leak. Eleven of 12 patients with a CSF leak documented by CTM also had extradural fluid collections on spinal MRI (sensitivity 91.7%). Six patients with extradural fluid collections on spinal MRI also had spinal dural enhancement. When compared with the gold standard of CTM, MRI of the spine appears to be a sensitive and less invasive imaging modality for detecting a spinal CSF leak, suggesting that MRI of the spine should be the imaging modality of first choice for the detection of spinal CSF leaks.

Endoscopic transpterygoidal repair of a large cranial defect with cerebrospinal fluid leak in a patient with extensive osteoradionecrosis of the skull base: case report and technical note.

PubMed

Brand, Y; Lim, E; Waran, V; Prepageran, N

2015-12-01

Endoscopic endonasal techniques have recently become the method of choice in dealing with cerebrospinal fluid leak involving the anterior cranial fossa. However, most surgeons prefer an intracranial approach when leaks involve the middle cranial fossa. This case report illustrates the possibilities of using endoscopic techniques for cerebrospinal fluid leaks involving the middle fossa. A 37-year-old male patient presented with multiple areas of cranial defect with cerebrospinal fluid leak due to osteoradionecrosis following radiation for nasopharyngeal carcinoma 4 years earlier. Clinical examination showed involvement of all cranial nerves except the IInd and XIth nerves on the left side. A prior attempt to repair the cerebrospinal fluid leak with craniotomy was not successful. This case demonstrates the successful endoscopic repair of a large cranial defect with cerebrospinal fluid leak.

Leak detectability of the Norman Wells pipeline by mass balance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liou, J.C.P.

Pipeline leak detection using software-based systems is becoming common practice. The detectability of such systems is measured by how small and how quickly a leak can be detected. Algorithms used and measurement uncertainties determine leak detectability. This paper addresses leak detectability using mass balance, establishes leak detectability for Norman Wells pipelines, and compares it with field leak test results. The pipeline is operated by the Interprovincial Pipe Line (IPL) Inc., of Edmonton, Canada. It is a 12.75-inch outside diameter steel pipe with variable wall thickness. The length of the pipe is approximately 550 miles (868.9 km). The pipeline transports lightmore » crude oil at a constant flow rate of about 250 m{sup 3}/hr. The crude oil can enter the pipeline at two locations. Besides the Norman Wells inlet, there is a side line near Zama terminal that can inject crude oil into the pipeline.« less

40 CFR 1066.985 - Fuel storage system leak test procedure.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Fuel storage system leak test... Refueling Emission Test Procedures for Motor Vehicles § 1066.985 Fuel storage system leak test procedure. (a... conditions. (3) Leak test equipment must have the ability to pressurize fuel storage systems to at least 4.1...

75 FR 76742 - Detecting Oil Leaks From Vessels Into the Water

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-09

... to detect leaks from oil tanks into the water? (E) What is the threshold for detection, accuracy... than leak detection from oil cargo tanks into the water? (H) Are methods or equipment being applied for... DEPARTMENT OF HOMELAND SECURITY Coast Guard [Docket No. USCG-2010-1085] Detecting Oil Leaks From...

Measuring Small Leak Holes

NASA Technical Reports Server (NTRS)

Koch, D. E.; Stephenson, J. G.

1983-01-01

Hole sizes deduced from pressure measurements. Measuring apparatus consists of pitot tube attached to water-filled manometer. Compartment tested is pressurized with air. Pitot probe placed at known distance from leak. Dynamic pressure of jet measured at that point and static pressure measured in compartment. Useful in situations in which small leaks are tolerable but large leaks are not.

40 CFR 63.11495 - What are the management practices and other requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... or demonstrate that the HAP concentration in the cooling water does not constitute a leak, as defined... vessels and equipment are sound and free of leaks. For these inspections, detection methods incorporating...) inspection of all areas of potential leak within the CMPU. Indications of a leak identified using such method...

The Leaking-Toilet Challenge

ERIC Educational Resources Information Center

Roman, Harry T.

2008-01-01

Leaking toilets can cost homeowners big dollars--often before it is even realized. Homeowners do not necessarily hear it leaking. It just does, and when the water bill comes due, it can be a most unpleasant surprise. This article presents a classroom challenge to try to develop leak-detection ideas that would be inexpensive and easily added to…

Leaking and Death-Threats by Students: A Study in German Schools

ERIC Educational Resources Information Center

Bondü, Rebecca; Scheithauer, Herbert

2014-01-01

Leaking comprises observable behavior or statements that signal intentions of committing a violent offense and is considered an important warning sign for school shootings. School staff who are confronted with leaking have to assess its seriousness and react appropriately--a difficult task, because knowledge about leaking is sparse. The present…

1999 Leak Detection and Monitoring and Mitigation Strategy Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

OHL, P.C.

This document is a complete revision of WHC-SD-WM-ES-378, Rev 1. This update includes recent developments in Leak Detection, Leak Monitoring, and Leak Mitigation technologies, as well as, recent developments in single-shell tank retrieval technologies. In addition, a single-shell tank retrieval release protection strategy is presented.

Leak Detection and Location Technology Assessment for Aerospace Applications

NASA Technical Reports Server (NTRS)

Wilson, William C.; Coffey, Neil C.; Madaras, Eric I.

2008-01-01

Micro Meteoroid and Orbital Debris (MMOD) and other impacts can cause leaks in the International Space Station and other aerospace vehicles. The early detection and location of leaks is paramount to astronaut safety. Therefore this document surveys the state of the art in leak detection and location technology for aerospace vehicles.

Can the intraoperative leak test prevent postoperative leakage of esophagojejunal anastomosis after total gastrectomy?

PubMed

Kanaji, Shingo; Ohyama, Masato; Yasuda, Takashi; Sendo, Hiroyoshi; Suzuki, Satoshi; Kawasaki, Kentaro; Tanaka, Kenichi; Fujino, Yasuhiro; Tominaga, Masahiro; Kakeji, Yoshihiro

2016-07-01

Anastomotic failures that cannot be detected during surgery often lead to postoperative leakage. There have been no detailed reports on the intraoperative leak test for esophagojejunal anastomosis. Our purpose was to investigate the utility of routine intraoperative leak testing to prevent postoperative anastomotic leakage after performing esophagojejunostomy. We prospectively performed routine air leak tests and reviewed the records of 185 consecutive patients with gastric cancer who underwent open total gastrectomy followed by esophagojejunostomy. A positive leak test was found for six patients (3.2 %). These patients with positive leak tests were subsequently treated with additional suturing, and they developed no postoperative anastomotic leakage. However, anastomotic leakage occurred in nine patients (4.9 %) with negative leak tests. A multivariate analysis demonstrated that a patient age >75 years and the surgeon's experience <30 cases were risk factors for anastomotic leakage. Intraoperative leak testing can detect some physical dehiscence, and additional suturing may prevent anastomotic leakage. However, it cannot prevent all anastomotic leakage caused by other factors, such as the surgeons' experience and patients' age.

Vehicle-based Methane Mapping Helps Find Natural Gas Leaks and Prioritize Leak Repairs

NASA Astrophysics Data System (ADS)

von Fischer, J. C.; Weller, Z.; Roscioli, J. R.; Lamb, B. K.; Ferrara, T.

2017-12-01

Recently, mobile methane sensing platforms have been developed to detect and locate natural gas (NG) leaks in urban distribution systems and to estimate their size. Although this technology has already been used in targeted deployment for prioritization of NG pipeline infrastructure repair and replacement, one open question regarding this technology is how effective the resulting data are for prioritizing infrastructure repair and replacement. To answer this question we explore the accuracy and precision of the natural gas leak location and emission estimates provided by methane sensors placed on Google Street View (GSV) vehicles. We find that the vast majority (75%) of methane emitting sources detected by these mobile platforms are NG leaks and that the location estimates are effective at identifying the general location of leaks. We also show that the emission rate estimates from mobile detection platforms are able to effectively rank NG leaks for prioritizing leak repair. Our findings establish that mobile sensing platforms are an efficient and effective tool for improving the safety and reducing the environmental impacts of low-pressure NG distribution systems by reducing atmospheric methane emissions.

Imaging review of cerebrospinal fluid leaks

PubMed Central

Vemuri, Naga V; Karanam, Lakshmi S P; Manchikanti, Venkatesh; Dandamudi, Srinivas; Puvvada, Sampath K; Vemuri, Vineet K

2017-01-01

Cerebrospinal fluid (CSF) leak occurs due to a defect in the dura and skull base. Trauma remains the most common cause of CSF leak; however, a significant number of cases are iatrogenic, and result from a complication of functional endoscopic sinus surgery (FESS). Early diagnosis of CSF leak is of paramount importance to prevent life-threatening complications such as brain abscess and meningitis. Imaging plays a crucial role in the detection and characterization of CSF leaks. Three-dimensional, isotropic, high resolution computed tomography (HRCT) accurately detects the site and size of the bony defect. CT cisternography, though invasive, helps accurately identify the site of CSF leak, especially in the presence of multiple bony defects. Magnetic resonance imaging (MRI) accurately detects CSF leaks and associated complications such as the encephaloceles and meningoceles. In this review, we emphasize the importance and usefulness of 3D T2 DRIVE MR cisternography in localizing CSF leaks. This sequence has the advantages of effective bone and fat suppression, decreased artefacts, faster acquisition times, three-dimensional capability, y and high spatial resolution in addition to providing very bright signal from the CSF. PMID:29379240

Imaging review of cerebrospinal fluid leaks.

PubMed

Vemuri, Naga V; Karanam, Lakshmi S P; Manchikanti, Venkatesh; Dandamudi, Srinivas; Puvvada, Sampath K; Vemuri, Vineet K

2017-01-01

Cerebrospinal fluid (CSF) leak occurs due to a defect in the dura and skull base. Trauma remains the most common cause of CSF leak; however, a significant number of cases are iatrogenic, and result from a complication of functional endoscopic sinus surgery (FESS). Early diagnosis of CSF leak is of paramount importance to prevent life-threatening complications such as brain abscess and meningitis. Imaging plays a crucial role in the detection and characterization of CSF leaks. Three-dimensional, isotropic, high resolution computed tomography (HRCT) accurately detects the site and size of the bony defect. CT cisternography, though invasive, helps accurately identify the site of CSF leak, especially in the presence of multiple bony defects. Magnetic resonance imaging (MRI) accurately detects CSF leaks and associated complications such as the encephaloceles and meningoceles. In this review, we emphasize the importance and usefulness of 3D T2 DRIVE MR cisternography in localizing CSF leaks. This sequence has the advantages of effective bone and fat suppression, decreased artefacts, faster acquisition times, three-dimensional capability, y and high spatial resolution in addition to providing very bright signal from the CSF.

A method for simulating the entire leaking process and calculating the liquid leakage volume of a damaged pressurized pipeline.

PubMed

He, Guoxi; Liang, Yongtu; Li, Yansong; Wu, Mengyu; Sun, Liying; Xie, Cheng; Li, Feng

2017-06-15

The accidental leakage of long-distance pressurized oil pipelines is a major area of risk, capable of causing extensive damage to human health and environment. However, the complexity of the leaking process, with its complex boundary conditions, leads to difficulty in calculating the leakage volume. In this study, the leaking process is divided into 4 stages based on the strength of transient pressure. 3 models are established to calculate the leaking flowrate and volume. First, a negative pressure wave propagation attenuation model is applied to calculate the sizes of orifices. Second, a transient oil leaking model, consisting of continuity, momentum conservation, energy conservation and orifice flow equations, is built to calculate the leakage volume. Third, a steady-state oil leaking model is employed to calculate the leakage after valves and pumps shut down. Moreover, sensitive factors that affect the leak coefficient of orifices and volume are analyzed respectively to determine the most influential one. To validate the numerical simulation, two types of leakage test with different sizes of leakage holes were conducted from Sinopec product pipelines. More validations were carried out by applying commercial software to supplement the experimental insufficiency. Thus, the leaking process under different leaking conditions are described and analyzed. Copyright © 2017 Elsevier B.V. All rights reserved.

Water-soluble upper GI based on clinical findings is reliable to detect anastomotic leaks after laparoscopic gastric bypass.

PubMed

Katasani, V G; Leeth, R R; Tishler, D S; Leath, T D; Roy, B P; Canon, C L; Vickers, S M; Clements, R H

2005-11-01

Anastomotic leak after laparoscopic Roux-en-Y gastric bypass (LGB) is a major complication that must be recognized and treated early for best results. There is controversy in the literature regarding the reliability of upper GI series (UGI) in diagnosing leaks. LGB was performed in patients meeting NIH criteria for the surgical treatment of morbid obesity. All leaks identified at the time of surgery were repaired with suture and retested. Drains were placed at the surgeon's discretion. Postoperatively, UGI was performed by an experienced radiologist if there was a clinical suspicion of leak. From September 2001 until October 2004, a total of 553 patients (age 40.4 +/- 9.2 years, BMI 48.6 +/- 7.2) underwent LGB at UAB. Seventy-eight per cent (431 of 553) of patients had no clinical evidence suggesting anastomotic leak and were managed expectantly. Twenty-two per cent (122 of 553) of patients met at least one inclusion criteria for leak and underwent UGI. Four of 122 patients (3.2%) had a leak, two from anastomosis and two from the perforation of the stapled end of the Roux limb. No patient returned to the operating room without a positive UGI. High clinical suspicion and selectively performed UGI based on clinical evidence is reliable in detecting leaks.

Vanishing calcification associated with a spontaneous ventral spinal cerebrospinal fluid leak.

PubMed

Schievink, Wouter I; Ross, Lindsey; Prasad, Ravi S; Maya, M Marcel

2016-12-01

Some patients with spontaneous intracranial hypotension have a ventral spinal cerebrospinal fluid (CSF) leak and these CSF leaks may be associated with calcified disk herniations. Identifying these calcifications is helpful in directing treatment. We report here the unusual case of a patient with a ventral CSF leak in whom the associated calcification absorbed over a five-month period. A 42-year-old woman developed orthostatic headaches and bilateral abducens nerve palsies. Magnetic resonance imaging of her brain showed typical findings of spontaneous intracranial hypotension. Magnetic resonance imaging of her spine showed an extensive cervicothoracic CSF leak. Computed tomographic myelography showed calcification at the Th1-2 disk space. Three epidural blood patches were performed, but her symptoms persisted. Digital subtraction myelography performed five months later showed an upper thoracic ventral CSF, but the calcification was no longer present. A dural tear, found at surgery at the Th1-2 level, was repaired and the patient made an uneventful recovery. The resorption of calcifications at the level of a ventral spinal CSF leak could explain the absence of any calcifications in at least some patients with such leaks and demonstrates the usefulness of reviewing previous imaging in patients with ventral CSF leaks if the exact site of the leak remains unknown. © International Headache Society 2016.

Left Atrial Appendage Eccentricity and Irregularity Are Associated With Residual Leaks After Percutaneous Closure.

PubMed

Rajwani, Adil; Shirazi, Masoumeh G; Disney, Patrick J S; Wong, Dennis T L; Teo, Karen S L; Delacroix, Sinny; Chokka, Ramesh G; Young, Glenn D; Worthley, Stephen G

2015-12-01

Predictors of residual leak following percutaneous LAA closure were evaluated. Left atrial appendage (LAA) closure aims to exclude this structure from the circulation, typically using a circular occluder. A noncircular orifice is frequently encountered however, and fibrous remodeling of the LAA in atrial fibrillation may restrict orifice deformation. Noncircularity may thus be implicated in the occurrence of residual leak despite an appropriately oversized device. Pre-procedural multislice computerized tomography was used to quantify LAA orifice eccentricity and irregularity. Univariate predictors of residual leak were identified with respect to the orifice, device, and relevant clinical variables, with the nature of any correlations then further evaluated. Eccentricity and irregularity indexes of the orifice in 31 individuals were correlated with residual leak even where the device was appropriately oversized. An eccentricity index of 0.15 predicted a residual leak with 85% sensitivity and 59% specificity. An irregularity index of 0.05 predicted a significant residual leak ≥3 mm with 100% sensitivity and 86% specificity. Orifice size, device size, degree of device oversize, left atrial volume, and pulmonary artery pressure were not predictors of residual leak. Eccentricity and irregularity of the LAA orifice are implicated in residual leak after percutaneous closure even where there is appropriate device over-size. Irregularity index in particular is a novel predictor of residual leak, supporting a closer consideration of orifice morphology before closure. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Neonatal air leak syndrome and the role of high-frequency ventilation in its prevention.

PubMed

Jeng, Mei-Jy; Lee, Yu-Sheng; Tsao, Pei-Chen; Soong, Wen-Jue

2012-11-01

Air leak syndrome includes pulmonary interstitial emphysema, pneumothorax, pneumomediastinum, pneumopericardium, pneumoperitoneum, subcutaneous emphysema, and systemic air embolism. The most common cause of air leak syndrome in neonates is inadequate mechanical ventilation of the fragile and immature lungs. The incidence of air leaks in newborns is inversely related to the birth weight of the infants, especially in very-low-birth-weight and meconium-aspirated infants. When the air leak is asymptomatic and the infant is not mechanically ventilated, there is usually no specific treatment. Emergent needle aspiration and/or tube drainage are necessary in managing tension pneumothorax or pneumopericardium with cardiac tamponade. To prevent air leak syndrome, gentle ventilation with low pressure, low tidal volume, low inspiratory time, high rate, and judicious use of positive end expiratory pressure are the keys to caring for mechanically ventilated infants. Both high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) can provide adequate gas exchange using extremely low tidal volume and supraphysiologic rate in neonates with acute pulmonary dysfunction, and they are considered to have the potential to reduce the risks of air leak syndrome in neonates. However, there is still no conclusive evidence that HFOV or HFJV can help to reduce new air leaks in published neonatal clinical trials. In conclusion, neonatal air leaks may present as a thoracic emergency requiring emergent intervention. To prevent air leak syndrome, gentle ventilations are key to caring for ventilated infants. There is insufficient evidence showing the role of HFOV and HFJV in the prevention or reduction of new air leaks in newborn infants, so further investigation will be necessary for future applications. Copyright © 2012. Published by Elsevier B.V.

Technical basis for inner container leak detection sensitivity goals in 3013 DE surveillance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, John M.

Helium leak checking of 3013 inner container lids is under consideration for addition to DE Surveillance tasks as an improved means to detect any through-wall flaws that may have formed during storage. This white paper evaluates whether leak checking at DE could replace and improve upon the current method of comparing gas compositions and pressures within the inner and outer containers. We have used viscous and molecular flow equations in ANSI N14.5 to calculate what the measured standard helium leak rate would be for hypothetical leaks of three different sizes. For comparison, we have also calculated the effects on gasmore » composition and pressure differences as a function of pre-DE storage time for the same three leak sizes, using molecular and viscous flow equations as well as diffusion equations to predict the relevant gas transport. For a hypothetical leak that would be measured at 1x10 -7 std cc/sec, likely an achievable sensitivity using helium leak checking at DE, the calculations predict no measurable effect on pressure difference or gas composition as measured by DE gas analysis. We also calculate that it would take over 200 years for water vapor to diffuse through a 10 -7 std cc/sec leak enough to raise the RH outer container to half the RH value in the inner container. A leak 100 times larger, which would be measured at 1x10 -5 std cc/sec, the same water vapor diffusion would take at least 14 years. Our conclusion is that helium leak checking will be useful even at a sensitivity of 1x10 -5 std cc/sec, and a significant improvement over current DE methods at a sensitivity of 1x10 -7 std cc/sec.« less

High prevalence of baffle leaks in adults after atrial switch operations for transposition of the great arteries.

PubMed

De Pasquale, Gabriella; Bonassin Tempesta, Francesca; Lopes, Bruno Santos; Babic, Daniela; Oxenius, Angela; Seeliger, Theresa; Gruner, Christiane; Tanner, Felix C; Biaggi, Patric; Attenhofer Jost, Christine; Greutmann, Matthias

2017-05-01

To determine the prevalence of baffle leaks in adults after atrial switch operations for transposition of the great arteries, as these may predispose to paradoxical embolic events, particularly in patients with transvenous pacemaker or defibrillator leads. We routinely perform contrast echocardiography with agitated saline in all patients after atrial switch operations. For this study, we analysed patients who had saline contrast echocardiography between 2010 and 2012. The presence of baffle leaks and the severity of right-to-left shunting were assessed. We compared baseline characteristics and oxygen saturation at rest and during exercise between patients with and without baffle leaks. A total of 65 patients (56 Senning and 9 Mustard repair) without previously known baffle leaks were included (mean age 32 ± 8 years, 77% males). Right-to-left shunting was identified in 42 patients (65%) and occurred without provocation manoeuvres in 88%. There were no differences in baseline characteristics, echocardiographic findings, or exercise capacity between patients with and without baffle leaks, except for lower oxygen saturation at peak exercise in those with baffle leaks (29% had oxygen saturations below 90% at peak exercise compared to none without baffle leaks, P = 0.011). Four patients with baffle leaks had previous implantation of transvenous pacemaker leads; one of them had suffered a stroke. Two other patients with baffle leaks had a history of potential embolic stroke. Because of the high prevalence of baffle leaks in adults after atrial switch operations, we propose routine screening with agitated saline contrast, particularly prior to implantation of transvenous pacemaker or defibrillator leads. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Individual surgeon is an independent risk factor for leak after double-stapled colorectal anastomosis: An institutional analysis of 800 patients.

PubMed

García-Granero, Eduardo; Navarro, Francisco; Cerdán Santacruz, Carlos; Frasson, Matteo; García-Granero, Alvaro; Marinello, Franco; Flor-Lorente, Blas; Espí, Alejandro

2017-11-01

Our aim was to assess whether the individual surgeon is an independent risk factor for anastomotic leak in double-stapled colorectal anastomosis after left colon and rectal cancer resection. This retrospective analysis of a prospectively collected database consists of a consecutive series of 800 patients who underwent an elective left colon and rectal resection with a colorectal, double-stapled anastomosis between 1993 and 2009 in a specialized colorectal unit of a tertiary hospital with 7 participating surgeons. The main outcome variable was anastomotic leak, defined as leak of luminal contents from a colorectal anastomosis between 2 hollow viscera diagnosed radiologically, clinically, endoscopically, or intraoperatively. Pelvic abscesses were also considered to be an anastomotic leak. Radiologic examination was performed when there was clinical suspicion of leak. Anastomotic leak occurred in 6.1% of patients, of which 33 (67%) were treated operatively, 6 (12%) with radiologic drains, and 10 (21%) by medical treatment. Postoperative mortality rate was 2.9% for the whole group of 800 patients. In patients with anastomotic leak, mortality rate increased up to 16% vs 2.0% in patients without anastomotic leak (P < .0001). At multivariate analysis, rectal location of tumor, male sex, bowel obstruction preoperatively, tobacco use, diabetes, perioperative transfusion, and the individual surgeon were independent risk factors for anastomotic leak. The surgeon was the most important factor (mean odds ratio 4.9; range 1.0 to 13.5). The variance of anastomotic leak between the different surgeons was 0.56 in the logit scale. The individual surgeon is an independent risk factor for leakage in double-stapled, colorectal, end-to-end anastomosis after oncologic left-sided colorectal resection. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessing surgeon behavior change after anastomotic leak in colorectal surgery.

PubMed

Simianu, Vlad V; Basu, Anirban; Alfonso-Cristancho, Rafael; Thirlby, Richard C; Flaxman, Abraham D; Flum, David R

2016-10-01

Recency effect suggests that people disproportionately value events from the immediate past when making decisions, but the extent of this impact on surgeons' decisions is unknown. This study evaluates for recency effect in surgeons by examining use of preventative leak testing before and after colorectal operations with anastomotic leaks. Prospective cohort of adult patients (≥18 y) undergoing elective colorectal operations at Washington State hospitals participating in the Surgical Care and Outcomes Assessment Program (2006-2013). The main outcome measure was surgeons' change in leak testing from 6 mo before to 6 mo after an anastomotic leak occurred. Across 4854 elective colorectal operations performed by 282 surgeons at 44 hospitals, there was a leak rate of 2.6% (n = 124). The 40 leaks (32%) in which the anastomosis was not tested occurred across 25 surgeons. While the ability to detect an overall difference in use of leak testing was limited by small sample size, nine (36%) of 25 surgeons increased their leak testing by 5% points or more after leaks in cases where the anastomosis was not tested. Surgeons who increased their leak testing more frequently performed operations for diverticulitis (45% versus 33%), more frequently began their cases laparoscopically (65% versus 37%), and had longer mean operative times (195 ± 99 versus 148 ± 87 min), all P < 0.001. Recency effect was demonstrated by only one-third of eligible surgeons. Understanding the extent to which clinical decisions may be influenced by recency effect may be important in crafting quality improvement initiatives that require clinician behavior change. Copyright © 2016 Elsevier Inc. All rights reserved.

Patient and surgical factors influencing air leak after lung volume reduction surgery: lessons learned from the National Emphysema Treatment Trial.

PubMed

DeCamp, Malcolm M; Blackstone, Eugene H; Naunheim, Keith S; Krasna, Mark J; Wood, Douglas E; Meli, Yvonne M; McKenna, Robert J

2006-07-01

Although staple line buttressing is advocated to reduce air leak after lung volume reduction surgery (LVRS), its effectiveness is unknown. We sought to identify risk factors for air leak and its duration and to estimate its medical consequences for selecting optimal perioperative technique(s), such as buttressing technique, to preempt or treat post-LVRS air leak. Detailed air leak data were available for 552 of 580 patients receiving bilateral stapled LVRS in the National Emphysema Treatment Trial. Risk factors for prevalence and duration of air leak were identified by logistic and hazard function analyses. Medical consequences were estimated in propensity-matched pairs with and without air leak. Within 30 days of LVRS, 90% of patients developed air leak (median duration = 7 days). Its occurrence was more common and duration prolonged in patients with lower diffusing capacity (p = 0.06), upper lobe disease (p = 0.04), and important pleural adhesions (p = 0.007). Duration was also protracted in Caucasians (p < 0.0001), patients using inhaled steroids (p = 0.004), and those with lower 1-second forced expiratory volume (p = 0.0003). Surgical approach, buttressing, stapler brand, and intraoperative adjunctive procedures were not associated with fewer or less prolonged air leaks (p >/= 0.2). Postoperative complications occurred more often in matched patients experiencing air leak (57% vs 30%, p = 0.0004), and postoperative stay was longer (11.8 +/- 6.5 days vs 7.6 +/- 4.4 days, p = 0.0005). Air leak accompanies LVRS in 90% of patients, is often prolonged, and is associated with a more complicated and protracted hospital course. Its occurrence and duration are associated with characteristics of patients and their disease, not with a specific surgical technique.

Using Decision Trees to Detect and Isolate Simulated Leaks in the J-2X Rocket Engine

NASA Technical Reports Server (NTRS)

Schwabacher, Mark A.; Aguilar, Robert; Figueroa, Fernando F.

2009-01-01

The goal of this work was to use data-driven methods to automatically detect and isolate faults in the J-2X rocket engine. It was decided to use decision trees, since they tend to be easier to interpret than other data-driven methods. The decision tree algorithm automatically "learns" a decision tree by performing a search through the space of possible decision trees to find one that fits the training data. The particular decision tree algorithm used is known as C4.5. Simulated J-2X data from a high-fidelity simulator developed at Pratt & Whitney Rocketdyne and known as the Detailed Real-Time Model (DRTM) was used to "train" and test the decision tree. Fifty-six DRTM simulations were performed for this purpose, with different leak sizes, different leak locations, and different times of leak onset. To make the simulations as realistic as possible, they included simulated sensor noise, and included a gradual degradation in both fuel and oxidizer turbine efficiency. A decision tree was trained using 11 of these simulations, and tested using the remaining 45 simulations. In the training phase, the C4.5 algorithm was provided with labeled examples of data from nominal operation and data including leaks in each leak location. From the data, it "learned" a decision tree that can classify unseen data as having no leak or having a leak in one of the five leak locations. In the test phase, the decision tree produced very low false alarm rates and low missed detection rates on the unseen data. It had very good fault isolation rates for three of the five simulated leak locations, but it tended to confuse the remaining two locations, perhaps because a large leak at one of these two locations can look very similar to a small leak at the other location.

Interaction Between Neuronal NOS Signaling and Temperature Influences SR Ca2+ Leak:Role of Nitroso-Redox Balance

PubMed Central

Dulce, Raul A.; Mayo, Vera; Rangel, Erika B.; Balkan, Wayne; Hare, Joshua M.

2014-01-01

Rationale While nitric oxide (NO) signaling modulates cardiac function and excitation-contraction coupling, opposing results due to inconsistent experimental conditions, particularly with respect to temperature, confound the ability to elucidate NO signaling pathways. Here we show that temperature significantly modulates NO effects. Objective Test the hypothesis that temperature profoundly impacts nitroso-redox equilibrium, thereby affecting sarcomeric reticulum (SR) Ca2+ leak. Methods and Results We measured SR Ca2+ leak in cardiomyocytes from wild-type (WT), NO/redox imbalance (NOS1−/−), and hyper S-nitrosylation (GSNOR−/−) mice. In WT cardiomyocytes, SR Ca2+ leak increased as temperature decreased from 37°C to 23°C, whereas, in NOS1−/ −cells, the leak suddenly increased when the temperature surpassed 30°C. GSNOR−/ − cardiomyocytes exhibited low leak throughout the temperature range. Exogenously added NO had a biphasic effect on NOS1−/− cardiomyocytes; reducing leak at 37°C but increasing it at sub-physiologic temperatures. Oxypurinol and Tempol diminished the leak in NOS1−/ − cardiomyocytes. Cooling from 37° to 23°C increased ROS generation in WT but decreased it in NOS1−/− cardiomyocytes. Oxypurinol further reduced ROS generation. At 23°C in WT cells, leak was decreased by tetrahydrobiopterin, an essential NOS cofactor. Cooling significantly increased SR Ca2+ content in NOS1−/− cells but had no effect in WT or GSNOR−/−. Conclusions Ca2+ leak and temperature are normally inversely proportional, whereas NOS1 deficiency reverses this effect, increasing leak and elevating ROS production as temperature increases. Reduced denitrosylation (GSNOR deficiency) eliminates the temperature dependence of leak. Thus, temperature regulates the balance between NO and ROS which in turn has a major impact on SR Ca2+. PMID:25326127

Interaction between neuronal nitric oxide synthase signaling and temperature influences sarcoplasmic reticulum calcium leak: role of nitroso-redox balance.

PubMed

Dulce, Raul A; Mayo, Vera; Rangel, Erika B; Balkan, Wayne; Hare, Joshua M

2015-01-02

Although nitric oxide (NO) signaling modulates cardiac function and excitation-contraction coupling, opposing results because of inconsistent experimental conditions, particularly with respect to temperature, confound the ability to elucidate NO signaling pathways. Here, we show that temperature significantly modulates NO effects. To test the hypothesis that temperature profoundly affects nitroso-redox equilibrium, thereby affecting sarcoplasmic reticulum (SR) calcium (Ca(2+)) leak. We measured SR Ca(2+) leak in cardiomyocytes from wild-type (WT), NO/redox imbalance (neuronal nitric oxide synthase-deficient mice-1 [NOS1(-/-)]), and hyper S-nitrosoglutathione reductase-deficient (GSNOR(-/-)) mice. In WT cardiomyocytes, SR Ca(2+) leak increased because temperature decreased from 37°C to 23°C, whereas in NOS1(-/-) cells, the leak suddenly increased when the temperature surpassed 30°C. GSNOR(-/-) cardiomyocytes exhibited low leak throughout the temperature range. Exogenously added NO had a biphasic effect on NOS1(-/-) cardiomyocytes; reducing leak at 37°C but increasing it at subphysiological temperatures. Oxypurinol and Tempol diminished the leak in NOS1(-/-) cardiomyocytes. Cooling from 37°C to 23°C increased reactive oxygen species generation in WT but decreased it in NOS1(-/-) cardiomyocytes. Oxypurinol further reduced reactive oxygen species generation. At 23°C in WT cells, leak was decreased by tetrahydrobiopterin, an essential NOS cofactor. Cooling significantly increased SR Ca(2+) content in NOS1(-/-) cells but had no effect in WT or GSNOR(-/-). Ca(2+) leak and temperature are normally inversely proportional, whereas NOS1 deficiency reverses this effect, increasing leak and elevating reactive oxygen species production because temperature increases. Reduced denitrosylation (GSNOR deficiency) eliminates the temperature dependence of leak. Thus, temperature regulates the balance between NO and reactive oxygen species which in turn has a major effect on SR Ca(2+). © 2014 American Heart Association, Inc.

40 CFR 51.164 - Stack height procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 51.164 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... source's stack height that exceeds good engineering practice or by any other dispersion technique, except... source based on a good engineering practice stack height that exceeds the height allowed by § 51.100(ii...

Of Detection Limits and Effective Mitigation: The Use of Infrared Cameras for Methane Leak Detection

NASA Astrophysics Data System (ADS)

Ravikumar, A. P.; Wang, J.; McGuire, M.; Bell, C.; Brandt, A. R.

2017-12-01

Mitigating methane emissions, a short-lived and potent greenhouse gas, is critical to limiting global temperature rise to two degree Celsius as outlined in the Paris Agreement. A major source of anthropogenic methane emissions in the United States is the oil and gas sector. To this effect, state and federal governments have recommended the use of optical gas imaging systems in periodic leak detection and repair (LDAR) surveys to detect for fugitive emissions or leaks. The most commonly used optical gas imaging systems (OGI) are infrared cameras. In this work, we systematically evaluate the limits of infrared (IR) camera based OGI system for use in methane leak detection programs. We analyze the effect of various parameters that influence the minimum detectable leak rates of infrared cameras. Blind leak detection tests were carried out at the Department of Energy's MONITOR natural gas test-facility in Fort Collins, CO. Leak sources included natural gas wellheads, separators, and tanks. With an EPA mandated 60 g/hr leak detection threshold for IR cameras, we test leak rates ranging from 4 g/hr to over 350 g/hr at imaging distances between 5 ft and 70 ft from the leak source. We perform these experiments over the course of a week, encompassing a wide range of wind and weather conditions. Using repeated measurements at a given leak rate and imaging distance, we generate detection probability curves as a function of leak-size for various imaging distances, and measurement conditions. In addition, we estimate the median detection threshold - leak-size at which the probability of detection is 50% - under various scenarios to reduce uncertainty in mitigation effectiveness. Preliminary analysis shows that the median detection threshold varies from 3 g/hr at an imaging distance of 5 ft to over 150 g/hr at 50 ft (ambient temperature: 80 F, winds < 4 m/s). Results from this study can be directly used to improve OGI based LDAR protocols and reduce uncertainty in estimated mitigation effectiveness. Furthermore, detection limits determined in this study can be used as standards to compare new detection technologies.

Blind Leak Detection for Closed Systems

NASA Technical Reports Server (NTRS)

Oelgoetz, Peter; Johnson, Ricky; Todd, Douglas; Russell, Samuel; Walker, James

2003-01-01

The current inspection technique for locating interstitial leaking in the Space Shuttle Main Engine nozzles is the application of a liquid leak check solution in the openings where the interstitials space between the tubing and the structural jacket vent out the aft end of the nozzle, while its cooling tubes are pressurized to 25 psig with Helium. When a leak is found, it is classified, and if the leak is severe enough the suspect tube is cut open so that a boroscope can be inserted to find the leak point. Since the boroscope can only cover a finite tube length and since it is impossible to identify which tube (to the right or left of the identified interstitial) is leaking, many extra and undesired repairs have been made to fix just one leak. In certain instances when the interstitials are interlinked by poor braze bonding, many interstitials will show indications of leaking from a single source. What is desired is a technique that can identify the leak source so that a single repair can be performed. Dr, Samuel Russell and James Walker, both with NASA/MSFC have developed a thermographic inspection system that addresses a single repair approach. They have teamed with Boeing/Rocketdyne to repackage the inspection processes to be suitable to address full scale Shuttle development and flight hardware and implement the process at NASA centers. The methods and results presented address the thermographic identification of interstitial leaks in the Space Shuttle Main Engine nozzles. A highly sensitive digital infrared camera (capable of detecting a delta temperature difference of 0.025 C) is used to record the cooling effects associated with a leak source, such as a crack or pinhole, hidden within the nozzle wall by observing the inner hot wall surface as the nozzle is pressurized, These images are enhanced by digitally subtracting a thermal reference image taken before pressurization. The method provides a non-intrusive way of locating the tube that is leaking and the exact leak source position to within a very small axial distance. Many of the factors that influence the inspectability of the nozzle are addressed; including pressure rate, peak pressure, gas type, ambient temperature and surface preparation. Other applications for this thermographic inspection system are the Reinforced-Carbon-Carbon (RCC) leading edge of the Space Shuttle orbiter and braze joint integrity.

Incidence and management of anastomotic leakage following laparoscopic prostatectomy with implementation of a new anastomotic technique incorporating posterior bladder neck tailoring.

PubMed

Sukkarieh, T; Harmon, J; Penna, F; Parra, R

2007-01-01

In laparoscopic prostatectomies, vesicourethral anastomotic leaks may result in significant morbidity because of the chemical and metabolic derangements created by urine within the peritoneal cavity. To date, minimal data are available on this problem. Herein we present our experience with urine leaks after RALP. Over a period of 24 months, 135 men underwent RALP. Any drainage creatinine greater than two times the serum creatinine was considered as an anastomotic leak. According to our criteria, 20% of the first 110 patients developed an anastomotic leak. The patients were analyzed in two groups, those with and without leaks. In the two groups, there was no statistically significant difference in age, height, weight, prostate volume and pre-op hemoglobin. The patients with leaks did have higher rate of prior abdominal surgery (50 vs. 36%), higher average pre-operative PSA values (7.6 vs. 6.1), higher rates of multiple biopsies (27 vs. 17%) and a higher average BMI (29.6 vs. 27.8). Intraoperative differences included an average of 30 min longer operative time and 66 cm(3) higher average EBL in patients with leaks. The transfusion rate was higher in the leak group at 18 vs. 1% in the no leak group. Recovery tended to be longer in patients with leaks, with hospital stays of an average of 3.6 days longer. The most common indication for prolonged hospitalization was ileus, which 55% of patients with leaks developed. Management included placing the catheter on mild traction, continuous antibiotics and taking the drain-off suction with caution to monitor the signs of a worsening ileus. In the last 25 patients, we revised our anastomotic technique. We now include posterior tailoring of the bladder neck prior to the vesicourethral anastomosis when the bladder neck is enlarged. This facilitates a water-tight anastomosis. Using this technique, we have yet to see the anastomotic leak. In RALPs, anastomotic leaks can lead to ileus formation and longer hospital stays. These leaks are associated with a higher average blood loss and transfusion rate. Management should focus on prevention. Since we have incorporated posterior bladder neck tailoring with the anastomosis, the problem has been markedly reduced.

Artificial Leaks in Container Closure Integrity Testing: Nonlinear Finite Element Simulation of Aperture Size Originated by a Copper Wire Sandwiched between the Stopper and the Glass Vial.

PubMed

Nieto, Alejandra; Roehl, Holger; Brown, Helen; Adler, Michael; Chalus, Pascal; Mahler, Hanns-Christian

2016-01-01

Container closure integrity (CCI) testing is required by different regulatory authorities in order to provide assurance of tightness of the container closure system against possible contamination, for example, by microorganisms. Microbial ingress CCI testing is performed by incubation of the container closure system with microorganisms under specified testing conditions. Physical CCI uses surrogate endpoints, such as coloration by dye solution ingress or gas flow (helium leakage testing). In order to correlate microbial CCI and physical CCI test methods and to evaluate the methods' capability to detect a given leak, artificial leaks are being introduced into the container closure system in a variety of different ways. In our study, artificial leaks were generated using inserted copper wires between the glass vial opening and rubber stopper. However, the insertion of copper wires introduces leaks of unknown size and shape. With nonlinear finite element simulations, the aperture size between the rubber stopper and the glass vial was calculated, depending on wire diameter and capping force. The dependency of the aperture size on the copper wire diameter was quadratic. With the data obtained, we were able to calculate the leak size and model leak shape. Our results suggest that the size as well as the shape of the artificial leaks should be taken into account when evaluating critical leak sizes, as flow rate does not, independently, correlate to hole size. Capping force also affected leak size. An increase in the capping force from 30 to 70 N resulted in a reduction of the aperture (leak size) by approximately 50% for all wire diameters. From 30 to 50 N, the reduction was approximately 33%. Container closure integrity (CCI) testing is required by different regulatory authorities in order to provide assurance of tightness of the container closure system against contamination, for example, by microorganisms. Microbial ingress CCI testing is performed by incubation of the container closure system with microorganisms under specified testing conditions. Physical CCI uses surrogate endpoints, such as coloration by dye solution ingress or gas flow. In order to correlate microbial ingress CCI and physical CCI test methods and to evaluate the methods' capability to detect a given leak, artificially created defects (artificial leaks) are being introduced into the container closure system in a variety of different ways. In our study, artificial leaks were generated using inserted copper wires between the glass vial opening and rubber stopper. Up to date, the insertion of copper wires introduced leaks of unknown size and shape. With nonlinear finite element simulations, the effective aperture size between the rubber stopper and the glass vial was calculated, depending on wire diameter and capping force, and the leak shape was modelled. Our results suggest that the size as well as the shape of the artificial leaks should be taken into account when evaluating critical leak sizes, as flow rate does not, independently, correlate to the hole size. © PDA, Inc. 2016.

40 CFR 63.11553 - What are my notification, reporting, and recordkeeping requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... operator that installs bag leak detection systems: “This facility has installed a bag leak detection system in accordance with § 63.11552(b)(3) or (c), has prepared a bag leak detection system monitoring plan in accordance with § 63.11552(c), and will operate each bag leak detection system according to the...

Detecting Methane Leaks

NASA Technical Reports Server (NTRS)

Grant, W. B.; Hinkley, E. D.

1984-01-01

Remote sensor uses laser radiation backscattered from natural targets. He/Ne Laser System for remote scanning of Methane leaks employs topographic target to scatter light to receiver near laser transmitter. Apparatus powered by 1.5kW generator transported to field sites and pointed at suspected methane leaks. Used for remote detection of natural-gas leaks and locating methane emissions in landfill sites.

46 CFR 56.97-38 - Initial service leak test (reproduces 137.7).

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Initial service leak test (reproduces 137.7). 56.97-38... PIPING SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-38 Initial service leak test (reproduces 137.7). (a) An initial service leak test and inspection is acceptable when other types of test are not...

40 CFR Table 3 to Subpart Hhhhh of... - Requirements for Equipment Leaks

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 13 2010-07-01 2010-07-01 false Requirements for Equipment Leaks 3... Manufacturing Pt. 63, Subpt. HHHHH, Table 3 Table 3 to Subpart HHHHH of Part 63—Requirements for Equipment Leaks... equipment leaks. For all . . . You must . . . 1. Equipment that is in organic HAP service at an existing...

Fluid leak indicator

NASA Technical Reports Server (NTRS)

Anderson, George E. (Inventor); Loo, Shu (Inventor)

1989-01-01

A fluid leak indicator (30) for detecting and indicating leaks in visually inaccessible fluid tubing joints (20, 21), such as those obstructed by insulation (24), includes a bag system (25) and a wicking system (30) surrounding or wrapping the joints (20, 21) under the visual obstructing material (24). Leaking fluid is collected in the bag (25) or on the wicking material (34) where it is conducted along the wicking material (34) to a visibly accessible capturing transparent indicator bulb (35) for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb (35).

Detection of leaks in buried rural water pipelines using thermal infrared images

USGS Publications Warehouse

Eidenshink, Jeffery C.

1985-01-01

Leakage is a major problem in many pipelines. Minor leaks called 'seeper leaks', which generally range from 2 to 10 m3 per day, are common and are difficult to detect using conventional ground surveys. The objective of this research was to determine whether airborne thermal-infrared remote sensing could be used in detecting leaks and monitoring rural water pipelines. This study indicates that such leaks can be detected using low-altitude 8.7- to 11.5. micrometer wavelength, thermal infrared images collected under proper conditions.

Design of oil pipeline leak detection and communication system based on optical fiber technology

NASA Astrophysics Data System (ADS)

Tu, Yaqing; Chen, Huabo

1999-08-01

The integrity of oil pipeline is always a major concern of operators. Pipeline leak not only leads to loss of oil, but pollutes environment. A new pipeline leak detection and communication system based on optical fiber technology to ensure the pipeline reliability is presented. Combined direct leak detection method with an indirect one, the system will greatly reduce the rate of false alarm. According, to the practical features of oil pipeline,the pipeline communication system is designed employing the state-of-the-art optic fiber communication technology. The system has such feature as high location accuracy of leak detection, good real-time characteristic, etc. which overcomes the disadvantages of traditional leak detection methods and communication system effectively.

The Use of Stitching and Bioabsorbable Mesh and Glue to Combat Prolonged Air Leaks.

PubMed

Tanaka, Toshiki; Ueda, Kazuhiro; Murakami, Junichi; Hamano, Kimikazu

2018-05-15

Prolonged postoperative air leaks are associated with extended periods of postoperative hospitalization, increased hospital costs, and an increased incidence of major cardiopulmonary complications. To prevent prolonged air leaks, we used small pieces of polyglycolic acid mesh as a pledget during the stitching of air leak sites. The stitched sites were then covered with mesh and fibrin glue. This novel technique showed the highest airway pressure tolerance in an ex vivo experimental study. There were no incidents of prolonged air leak among the five clinical cases in which this technique was initially applied. A large-scale study of patients with a high risk of prolonged air leak is warranted. Copyright © 2018. Published by Elsevier Inc.

Inhibition of tracheal vascular extravasation by liposome-encapsulated albuterol in rats.

PubMed

Zhang, W; Guo, L; Nadel, J A; Papahadjopoulos, D

1998-03-01

To develop a liposome-based system for systemic delivery of anti-inflammatory drugs to airways and other inflamed tissues. Postcapillary venular gap junctions open during airway inflammation and allow fluid accumulation and permit molecules (e.g. complement, kininogen) to enter tissues, initiating inflammatory cascades. Beta-adrenergic agonists prevent inflammatory plasma extravasation, but because of their deleterious side effects, they are not used intravenously. When sterically stabilized "stealth" liposomes are injected i.v., they remain in the circulation for long periods. Inflammatory mediators [e.g., substance P(SP)] open postcapillary venular gaps and allow liposomes and their contents to be deposited selectively in the inflamed tissue. We hypothesized that liposomes encapsulating a beta-adrenergic agonist, such as albuterol, would deposit selectively in inflamed airway tissue, where the drug would slowly leak out of the liposomes, resulting in closure of the gaps, thus preventing subsequent inflammatory extravasation. To test this hypothesis, we delivered albuterol-loaded liposomes i.v. in rats. Then we injected SP to open the venular gaps and allow accumulation of the drug-loaded liposomes in airway tissue. We examined whether this treatment resulted in inhibition of subsequent plasma extravasation induced by SP. The results indicate that liposome-encapsulated albuterol inhibits subsequent extravasation, presumably by leaking out of liposomes in airway tissue. This inhibition occurs for prolonged periods of time and with limited side effects compared to the effect of free albuterol. We conclude that liposomes loaded with appropriate drugs, by migrating to inflamed tissue and subsequently inhibiting inflammatory cascades, may be of therapeutic value in inflammatory diseases.

Structural and leakage integrity of tubes affected by circumferential cracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernalsteen, P.

1997-02-01

In this paper the author deals with the notion that circumferential cracks are generally considered unacceptable. He argues for the need to differentiate two facets of such cracks: the issue of the size and growth rate of a crack; and the issue of the structural strength and leakage potential of the tube in the presence of the crack. In this paper the author tries to show that the second point is not a major concern for such cracks. The paper presents data on the structural strength or burst pressure characteristics of steam generator tubes derived from models and data basesmore » of experimental work. He also presents a leak rate model, and compares the performance of circumferential and axial cracks as far as burst strength and leak rate. The final conclusion is that subject to improvement in NDE capabilities (sizing, detection, growth), that Steam Generator Defect Specific Management can be used to allow circumferentially degraded tubes to remain in service.« less

Evaluation of a Conductive Elastomer Seal for Spacecraft

NASA Technical Reports Server (NTRS)

Daniels, C. C.; Mather, J. L.; Oravec, H. A.; Dunlap, P. H., Jr.

2016-01-01

An electrically conductive elastomer was evaluated as a material candidate for a spacecraft seal. The elastomer used electrically conductive constituents as a means to reduce the resistance between mating interfaces of a sealed joint to meet spacecraft electrical bonding requirements. The compound's outgassing levels were compared against published NASA requirements. The compound was formed into a hollow O-ring seal and its compression set was measured. The O-ring seal was placed into an interface and the electrical resistance and leak rate were quantified. The amount of force required to fully compress the test article in the sealing interface and the force needed to separate the joint were also measured. The outgassing and resistance measurements were below the maximum allowable levels. The room temperature compression set and leak rates were fairly high when compared against other typical spacecraft seal materials, but were not excessive. The compression and adhesion forces were desirably low. Overall, the performance of the elastomer compound was sufficient to be considered for future spacecraft seal applications.

Outcomes of asymptomatic anastomotic leaks found on routine postoperative water-soluble enema following anterior resection for cancer.

PubMed

Killeen, S; Souroullas, P; Ho Tin, H; Hunter, I A; O'Grady, H; Gunn, J; Hartley, J E

2013-11-01

The incidence and consequence of an anastomotic leak associated with low anterior resection for cancer mandates covering stoma in most cases. A water-soluble enema is often performed to assess anastomotic integrity prior to stoma reversal. The functional outcome following reversal in patients with occult radiologically detected leaks is poorly defined. The goal of the present study was to determine the functional outcome in patients with a radiologically detected anastomotic leak who subsequently underwent stoma reversal. This case control study used patients with and without radiologically detected occult anastomotic leak having undergone reversal of covering stomata. The study group was matched with controls for age, gender, procedure, tumor stage, and adjuvant/neoadjuvant therapy. Validated fecal incontinence quality of life (FIQL), Cleveland Clinic Fecal Incontinence Score (CCFIS), and the Memorial Sloan-Kettering Cancer Center (MSKCC) Bowel Function Index (BFI) were used. Patient satisfaction, medication use, and ancillary procedures prior to closure were also recorded. Thirteen patients with radiologically detected occult anastomotic leaks and 13 matched controls were identified from a prospectively maintained database. The FIQL, CCFIS, and MSKCC BFI scores were significantly reduced in those with occult leaks. The mean number of radiological and surgical interventions was significantly greater in the patients with occult leaks. Antidiarrheal and bulking agent use, as well as patient satisfaction, were the same for both groups. Only one patient in the occult leak group would not undergo stoma reversal again. Reversal of a defunctioning ileostomy in the presence of an occult radiological leak can be associated with poorer functional outcomes, but patient satisfaction is undiminished.

False localizing sign of cervico-thoracic CSF leak in spontaneous intracranial hypotension.

PubMed

Schievink, Wouter I; Maya, M Marcel; Chu, Ray M; Moser, Franklin G

2015-06-16

Spontaneous spinal CSF leaks are an important cause of new-onset headaches. Such leaks are reported to be particularly common at the cervico-thoracic junction. The authors undertook a study to determine the significance of these cervico-thoracic CSF leaks. The patient population consisted of a consecutive group of 13 patients who underwent surgery for CSF leak repair based on CT myelography showing CSF extravasation at the cervico-thoracic junction but without any evidence of an underlying structural lesion. The mean age of the 9 women and 4 men was 41.2 years. Extensive extrathecal longitudinal CSF collections were demonstrated in 11 patients. At surgery, small leaking arachnoid cysts were found in 2 patients. In the remaining 11 patients, no clear source of CSF leakage could be identified at surgery. Resolution of symptoms was achieved in both patients with leaking arachnoid cysts, but in only 3 of the 11 patients with negative intraoperative findings. Postoperative spinal imaging was performed in 9 of the 11 patients with negative intraoperative findings and showed persistence of the longitudinal intraspinal extradural CSF. Further imaging revealed the site of the CSF leak to be ventral to the thoracic spinal cord. Five of these patients underwent microsurgical repair of the ventral CSF leak with resolution of symptoms in all 5 patients. Cervico-thoracic extravasation of dye on myelography does not necessarily indicate the site of the CSF leak. Treatment directed at this site should not be expected to have a high probability of sustained improvement of symptoms. © 2015 American Academy of Neurology.

Space Shuttle Main Engine Propellant Path Leak Detection Using Sequential Image Processing

NASA Technical Reports Server (NTRS)

Smith, L. Montgomery; Malone, Jo Anne; Crawford, Roger A.

1995-01-01

Initial research in this study using theoretical radiation transport models established that the occurrence of a leak is accompanies by a sudden but sustained change in intensity in a given region of an image. In this phase, temporal processing of video images on a frame-by-frame basis was used to detect leaks within a given field of view. The leak detection algorithm developed in this study consists of a digital highpass filter cascaded with a moving average filter. The absolute value of the resulting discrete sequence is then taken and compared to a threshold value to produce the binary leak/no leak decision at each point in the image. Alternatively, averaging over the full frame of the output image produces a single time-varying mean value estimate that is indicative of the intensity and extent of a leak. Laboratory experiments were conducted in which artificially created leaks on a simulated SSME background were produced and recorded from a visible wavelength video camera. This data was processed frame-by-frame over the time interval of interest using an image processor implementation of the leak detection algorithm. In addition, a 20 second video sequence of an actual SSME failure was analyzed using this technique. The resulting output image sequences and plots of the full frame mean value versus time verify the effectiveness of the system.

Endoscopic dilation for treatment of anastomotic leaks following transhiatal esophagectomy.

PubMed

Bhasin, D K; Sharma, B C; Gupta, N M; Sinha, S K; Singh, K

2000-06-01

Anastomotic leak is a known complication after transhiatal esophagectomy (THE) and cervical esophagogastric anastomosis. Conservative management takes a long time to heal such leaks. We assessed the role of endoscopic dilation in patients with anastomotic leak following THE. Eight consecutive patients (seven men, one woman; mean age 51) with anastomotic leak following THE were subjected to endoscopic dilation using Savary Gilliard dilators of 7-15 mm diameter. The mean interval between surgery and detection of leak was 9 days (range 5-22 days) and dilation was performed at a mean interval of 11.4 days (range 1-20 days) after detection of the leak. Drainage from fistulas stopped completely after 1-8 days (mean 3 days). X-ray with water soluble contrast showed closure of the fistula in all cases. Duration of follow-up ranged from 2 to 12 months. Anastomotic strictures developed in three patients. These patients required three sessions each of repeat dilation, and were alive at follow-up periods of 2, 4, and 12 months, respectively. One patient developed recurrence of growth at an anastomotic site. Four patients died because of distant metastasis. Bougie dilation of anastomotic sites is a safe and effective technique for the healing of anastomotic leaks following THE. However there is a need for a prospective randomized trial comparing endoscopic dilation with no dilation in patients with anastomotic leaks following THE.

Air leak after lung resection: pathophysiology and patients' implications.

PubMed

Pompili, Cecilia; Miserocchi, Giuseppe

2016-02-01

Protocols for the management of air leaks are critical aspects in the postoperative course of patients following lung resections. Many investigations in the last decade are focusing on the chest tube modalities or preventative measures, however, little is known about the pathophysiology of air leak and the patient perception of this common complication. This review concentrates on understanding the reasons why a pulmonary parenchyma may start to leak or an air leak may be longer than others. Experimental works support the notion that lung overdistension may favor air leak. These studies may represent the basis of future investigations. Furthermore, the standardization of nomenclature in the field of pleural space management and the creation of novel air leak scoring systems have contributed to improve the knowledge among thoracic surgeons and facilitate the organization of trials on this matter. We tried to summarize available evidences about the patient perception of a prolonged air leak and about what would be useful for them in order to prevent worsening of their quality of life. Future investigations are warranted to better understand the pathophysiologic mechanisms responsible of prolonged air leak in order to define tailored treatments and protocols. Improving the care at home with web-based telemonitoring or real time connected chest drainage may in a future improve the quality of life of the patients experience this complication and also enhance hospital finances.

Air leak after lung resection: pathophysiology and patients’ implications

PubMed Central

Miserocchi, Giuseppe

2016-01-01

Protocols for the management of air leaks are critical aspects in the postoperative course of patients following lung resections. Many investigations in the last decade are focusing on the chest tube modalities or preventative measures, however, little is known about the pathophysiology of air leak and the patient perception of this common complication. This review concentrates on understanding the reasons why a pulmonary parenchyma may start to leak or an air leak may be longer than others. Experimental works support the notion that lung overdistension may favor air leak. These studies may represent the basis of future investigations. Furthermore, the standardization of nomenclature in the field of pleural space management and the creation of novel air leak scoring systems have contributed to improve the knowledge among thoracic surgeons and facilitate the organization of trials on this matter. We tried to summarize available evidences about the patient perception of a prolonged air leak and about what would be useful for them in order to prevent worsening of their quality of life. Future investigations are warranted to better understand the pathophysiologic mechanisms responsible of prolonged air leak in order to define tailored treatments and protocols. Improving the care at home with web-based telemonitoring or real time connected chest drainage may in a future improve the quality of life of the patients experience this complication and also enhance hospital finances. PMID:26941970

40 CFR 63.11501 - What are the notification, recordkeeping, and reporting requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... receiver, and each delay of leak repair beyond 45 days for any heat exchange system with a cooling water..., demonstrations of indications of leaks that do not constitute leaks, repairs, and reasons for any delay in repair..., as specified in §§ 63.11496(f)(4) and 63.11410(g), and keep records of bag leak detection systems, as...

40 CFR Table 11 to Subpart G of... - Wastewater-Inspection and Monitoring Requirements for Waste Management Units

Code of Federal Regulations, 2010 CFR

2010-07-01

... openings for leaks Initially Semi-annually Visual. 63.133(c) Inspect floating roof in accordance with §§ 63.... Surface impoundments: 63.134(b)(1) Inspect cover and all openings for leaks Initially Semi-annually Visual... for leaks Initially Semi-annually Visual. 63.135(d)(1) Inspect enclosure and all openings for leaks...

40 CFR 61.243-2 - Alternative standards for valves in VHAP service-skip period leak detection and repair.

Code of Federal Regulations, 2010 CFR

2010-07-01

... VHAP service-skip period leak detection and repair. 61.243-2 Section 61.243-2 Protection of Environment... AIR POLLUTANTS National Emission Standard for Equipment Leaks (Fugitive Emission Sources) § 61.243-2 Alternative standards for valves in VHAP service—skip period leak detection and repair. (a)(1) An owner or...

Modeling and measurement of the performance of a branched conduit sampling system in a mass spectrometer leak detector

NASA Technical Reports Server (NTRS)

Russell, John M.

1994-01-01

In the leak testing of a large engineering system, one may distinguish three stages, namely leakage measurement by an overall enclosure, leak location, and leakage measurement by a local enclosure. Sniffer probes attached to helium mass spectrometer leak detectors are normally designed for leak location, a qualitative inspection technique intended to pinpoint where a leak is but not to quantify its rate of discharge. The main conclusion of the present effort is that local leakage measurement by a leak detector with a sniffer probe is feasible provided one has: (1) quantitative data on the performance of the mass separator cell (a device interior to the unit where the stream of fluid in the sample line branches); and (2) a means of stabilizing the mass transfer boundary layer that is created near a local leak site when a sniffer probe is placed in its immediate vicinity. Theoretical models of the mass separator cell are provided and measurements of the machine-specific parameters in the formulas are presented. A theoretical model of a porous probe end for stabilizing the mass transfer boundary is also presented.

Modeling and measurement of the performance of a branched conduit sampling system in a mass spectrometer leak detector

NASA Astrophysics Data System (ADS)

Russell, John M.

1994-10-01

In the leak testing of a large engineering system, one may distinguish three stages, namely leakage measurement by an overall enclosure, leak location, and leakage measurement by a local enclosure. Sniffer probes attached to helium mass spectrometer leak detectors are normally designed for leak location, a qualitative inspection technique intended to pinpoint where a leak is but not to quantify its rate of discharge. The main conclusion of the present effort is that local leakage measurement by a leak detector with a sniffer probe is feasible provided one has: (1) quantitative data on the performance of the mass separator cell (a device interior to the unit where the stream of fluid in the sample line branches); and (2) a means of stabilizing the mass transfer boundary layer that is created near a local leak site when a sniffer probe is placed in its immediate vicinity. Theoretical models of the mass separator cell are provided and measurements of the machine-specific parameters in the formulas are presented. A theoretical model of a porous probe end for stabilizing the mass transfer boundary is also presented.

Pipeline monitoring with unmanned aerial vehicles

NASA Astrophysics Data System (ADS)

Kochetkova, L. I.

2018-05-01

Pipeline leakage during transportation of combustible substances leads to explosion and fire thus causing death of people and destruction of production and accommodation facilities. Continuous pipeline monitoring allows identifying leaks in due time and quickly taking measures for their elimination. The paper describes the solution of identification of pipeline leakage using unmanned aerial vehicles. It is recommended to apply the spectral analysis with input RGB signal to identify pipeline damages. The application of multi-zone digital images allows defining potential spill of oil hydrocarbons as well as possible soil pollution. The method of multi-temporal digital images within the visible region makes it possible to define changes in soil morphology for its subsequent analysis. The given solution is cost efficient and reliable thus allowing reducing timing and labor resources in comparison with other methods of pipeline monitoring.

Differential impact of flow and mouth leak on oropharyngeal humidification during high-flow nasal cannula: a neonatal bench study.

PubMed

Ullrich, Tim Leon; Czernik, Christoph; Bührer, Christoph; Schmalisch, Gerd; Fischer, Hendrik Stefan

2018-06-01

Heated humidification is paramount during neonatal high-flow nasal cannula (HFNC) therapy. However, there is little knowledge about the influence of flow rate and mouth leak on oropharyngeal humidification and temperature. The effect of the Optiflow HFNC on oropharyngeal gas conditioning was investigated at flow rates of 4, 6 and 8 L min -1 with and without mouth leak in a bench model simulating physiological oropharyngeal air conditions during spontaneous breathing. Temperature and absolute humidity (AH) were measured using a digital thermo-hygrosensor. Without mouth leak, oropharyngeal temperature and AH increased significantly with increasing flow (P < 0.001). Mouth leak did not affect this increase up to 6 L min -1 , but at 8 L min -1 , temperature and AH plateaued, and the effect of mouth leak became statistically significant (P < 0.001). Mouth leak during HFNC had a negative impact on oropharyngeal gas conditioning when high flows were applied. However, temperature and AH always remained clinically acceptable.

Investigative techniques used to locate the liquid hydrogen leakage on the Space Shuttle Main Propulsion System

NASA Technical Reports Server (NTRS)

Hammock, William R., Jr.; Cota, Phillip E., Jr.; Rosenbaum, Bernard J.; Barrett, Michael J.

1991-01-01

Standard leak detection methods at ambient temperature have been developed in order to prevent excessive leakage from the Space Shuttle liquid oxygen and liquid hydrogen Main Propulsion System. Unacceptable hydrogen leakage was encountered on the Columbia and Atlantis flight vehicles in the summer of 1990 after the standard leak check requirements had been satisfied. The leakage was only detectable when the fuel system was exposed to subcooled liquid hydrogen during External Tank loading operations. Special instrumentation and analytical tools were utilized during a series of propellant tanking tests in order to identify the sources of the hydrogen leakage. After the leaks were located and corrected, the physical characteristics of the leak sources were analyzed in an effort to understand how the discrepancies were introduced and why the leakage had evaded the standard leak detection methods. As a result of the post-leak analysis, corrective actions and leak detection improvements have been implemented in order to preclude a similar incident.

Test Report of Special Form Qualification Testing for the ORNL U ZipCan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez, Oscar A.

This test report describes the special form testing activities performed on the two ZiPCans. One prototype test unit was subjected to the tests stipulated by 10 CFR 71.75 (d)(1)(i), ISO 2919:1999(E) Class 4 impact test, along with the leak rate test specified in 49 CFR 173.469(a)(4)(i). The other test unit was subjected to a leak rate test as specified in 173.469(a)(4)(i) and a heat test as specified in 49 CFR 173.469 (b)(4). Each test unit was leak tested before and after these respective tests. The leak rate tests performed were helium back-pressure tests and bubble tests, as specified in ANSImore » N14.5-2014.The measured leak rates were converted to standard condition leak rates as specified in ASTM E 493. The determined standardized leak rates from the test and calculation for both test units met the requirements for special form certification.« less

Theoretical and experimental investigation of magnetic field related helium leak in helium vessel of a large superconducting magnet

NASA Astrophysics Data System (ADS)

Bhattachryya, Pranab; Gupta, Anjan Dutta; Dhar, S.; Sarma, P. R.; Mukherjee, Paramita

2017-06-01

The helium vessel of the superconducting cyclotron (SCC) at the Variable Energy Cyclotron centre (VECC), Kolkata shows a gradual loss of insulation vacuum from 10-7 mbar to 10-4 mbar with increasing coil current in the magnet. The insulation vacuum restores back to its initial value with the withdrawal of current. The origin of such behavior has been thought to be related to the electromagnetic stress in the magnet. The electromagnetic stress distribution in the median plane of the helium vessel was studied to figure out the possible location of the helium leak. The stress field from the possible location was transferred to a simplified 2D model with different leak geometries to study the changes in conductance with coil current. The leak rate calculated from the changes in the leak geometry was compared with the leak rate calculated from the experimental insulation vacuum degradation behavior to estimate the initial leak shape and size.

Fatal Primary Capillary Leak Syndrome in a Late Preterm Newborn.

PubMed

Kulihova, Katarina; Prochazkova, Martina; Semberova, Jana; Janota, Jan

2016-10-01

Primary capillary leak syndrome is a rare disease of unknown etiology, characterized by episodes of vascular collapse and plasma extravasation, which may lead to multiple organ failure. Primary capillary leak is extremely rare in children. The authors report a case of a late preterm newborn with fatal capillary leak syndrome of unknown etiology, manifesting as hypotension unresponsive to treatment, extravasation leading to generalised edema, disseminated intravascular coagulation and finally, multiple organ dysfunction syndrome. Aggressive volumotherapy and a combination of inotropes and high doses of terlipressin did not influence systemic vascular collapse and plasma extravasation. The newborn developed multiple organ failure and died on day 27 of life. Investigations performed failed to reveal any specific cause of capillary leak. This is the first report of a fatal primary capillary leak syndrome in a newborn.

Methane, Ethane, and Propane Sensor for Real-time Leak Detection and Diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roscioli, Joseph R.; Herndon, Scott; Nelson, David D.

2017-03-24

The Phase I effort demonstrated the technical viability of a fast, sensitive, mobile hydrocarbon monitor. The instrument will enable the oil and gas industry, researchers, and regulators to rapidly identify and chemically profile leaks from facilities. This capability will allow operators to quickly narrow down and mitigate probable leaking equipment, minimizing product loss and penalties due to regulatory non-compliance. During the initial development phase, we demonstrated operation of a prototype monitor that is capable of measuring methane, ethane, and propane at sub-part-per-billion sensitivities in 1 second, using direct absorption infrared spectroscopy. To our knowledge, this is the first instrument capablemore » of fast propane measurements at atmospheric concentrations. In addition, the electrical requirements of the monitor have been reduced from the 1,200 W typical of a spectrometer, to <500 W, making it capable of being powered by a passenger vehicle, and easily deployed by the industry. The prototype monitor leverages recent advances in laser technology, using high-efficiency interband cascade lasers to access the 3 μm region of the mid-infrared, where the methane, ethane, and propane absorptions are strongest. Combined with established spectrometer technology, we have achieved precisions below 200 ppt for each compound. This allows the monitor to measure fast plumes from oil and gas facilities, as well as ambient background concentrations (typical ambient levels are 2 ppm, 1.5 ppb, and 0.7 ppb for methane, ethane and propane, respectively). Increases in instrument operating pressure were studied in order to allow for a smaller 125 W pump to be used, and passive cooling was explored to reduce the cooling load by almost 90% relative to active (refrigerated) cooling. In addition, the simulated infrared absorption profiles of ethane and propane were modified to minimize crosstalk between species, achieving <1% crosstalk between ethane and propane. Finally, a monitor was designed based upon the commercial compact mini-spectrometer capable of dual-laser operation. We intend to build and test this during phase II. Multiple opportunities for improvement were also identified. First, the reported ethane and propane concentrations are susceptible to external acceleration acting upon the instrument. During phase II we will address this “motion-sickness”. Second, significant software development will be needed operate the monitor at 1 second resolution in real time, and provide rapid, actionable data to a driver or passenger.« less

23 CFR 658.19 - Reasonable access.

Code of Federal Regulations, 2011 CFR

2011-04-01

... State may enact or enforce any law denying reasonable access to vehicles with dimensions authorized by...-semitrailer combination in which the semitrailer has a length not to exceed 28 feet (28.5 feet where allowed... not to exceed 281/2 feet and which generally operates as part of a vehicle combination described in...

Chemseal 3808-A2 penetration into small leak path

NASA Technical Reports Server (NTRS)

Carruth, M. R., Jr.; Dehaye, R. F.

1988-01-01

A possible fix to a leak in the oxidizer system of the Space Shuttle Discovery's attitude control system was proposed by MSFC. This fix involved the passing of a shuttlecock past the leaking Dynaflow fitting and sealing the vent tube containing the fitting with Chemseal 3808-A2. The question of whether the Chemseal 3808-A2 can flow into the leak path and provide a better seal was addressed analytically and by experiment to verify the analytical formula used. The results show that the equations are applicable and that the Chemseal will flow into the expected leak path and seal.

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 3 2013-10-01 2013-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 3 2011-10-01 2011-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 3 2012-10-01 2012-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 3 2014-10-01 2014-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

Demonstration of the BNL Continuous Dual Trap Analyzer to Detect Perfluorocarbon Tracers for the Tag, Track and Location Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heiser,J.H.; Adams, J.; Dietz, R..

2008-10-07

The Tag, Track and Location System (TTL) Program is investigating methods of tracking an asset using perfluorocarbon tracers (PFT). The success of any TTL method requires sound detection/location instrumentation. Tracer Detection Technologies Corp (TDT), through a contract with the Office of Naval Research (ONR), is investigating different detection systems. The detections systems generally fall into two categories; proximity detectors and standoff detectors. Proximity detectors, as the name implies, need to be in close proximity (e.g., meter to 10's of meters) to the PFT source. Standoff detection searches for the PFT from a greater distance away from the source (e.g., 100'smore » of meters to kilometers). Gas Chromatographs (GC) are generally considered a proximity detection systems, but in the case of PFTs should be considered for both proximity and standoff detection with the caveat that in standoff use the GC needs to be somewhere in the PFT plume, i.e., generally downwind of the source. With a properly sized PFT source, the right GC can afford fairly large standoff (distance from the source) distances; 100's of meters to kilometers downwind. Brookhaven National Laboratory (BNL) has such a GC system and offered to demonstrate the CDTA for TTL as a no cost addition to the TDTTTL project, of which BNL was a participant. BNL is a leading authority on the sampling, collection, release and detection of PFTs. In addition, the BNL team has extensive background in atmospheric dispersion, the application of PFTs to such studies and the development of applications utilizing PFTs such as building infiltration measurements, control room integrity determination, leak location and environmental investigations. This experience and expertise is essential in developing any PFT application were dispersion, dilution and overcoming environmental conditions and interferences are integral to success. BNL has developed sophisticated gas chromatography methods and instruments that allow detection of up to seven PFTs at part per quadrillion levels (1015) with sample times as short as 60 seconds. The Continuous Dual-Trap Analyzer (CDTA) was developed for leak hunting applications and can continuously sample the air for PFTs without interruption. Sample time can be as short as 60 seconds. The CDTA has been extensively used in the commercial sector to detect PFTs that have been introduced to leaking buried dielectric fluid-filled cables or leaking subsurface gas lines. The PFTs travel through the cable or pipe until they reach the leak site. PFTs then escape into the surrounding soil and permeate/diffuse to the surface where they can be detected with the CDTA. Typically a cable is tagged with ppm levels of PFTs resulting in ppt to ppq concentrations in the air at the leak site. The CDTA is proven to be rugged, reliable and has a proven track record of successful leak location. The application of the CDTA to PFT detection for TTL is identical to application for leak detection. The CDTA operator has a general idea, with a few miles of roadway, where the leak is located, but no specific knowledge of the location (it can be any where along the road). The CDTA is mounted in a Chevy Astro Van and is dispatched to the field. In the field the van is driven at nominally 15 mph along the road. The CDTA continuously samples the air outside the van (via a 1/4-inch plastic sample tube stuck out a side window) until a positive detection occurs. The van then covers the road section where the detection occurred at a slightly slower pace to pin-point the area where the leak is and to direct soil probe samples. The soil probe samples take soil gas samples every 10 yards or so and the samples are analyzed on the CDTA. The leak can be located to within a few feet in 95% of the cases. To date the CDTA has been successful in every leak hunt performed by BNL. One interesting case was a leak hunt that resulted in repeated negative detections. The confidence in the CDTA forced the utility to recheck its 'plumbing' which lead to the discovery that a valve was turned that shouldn't have been so that gas was being diverted rather than leaking (the pressure drop was due to this diversion of the gas to another line). For TTL application, a tagged item or person is known to be in a general area and can be located by detecting the PFT emanating from the tagging source. The CDTA can be deployed in the area and by sampling in a grid fashion (starting on the downwind side of the area of interest) can easily find even very small sources. The CDTA is a perfect match for this application and the leak hunt use basically a simulation of Track and Locate. No other PFT detection technology has the detection sensitivity, proven track record and ruggedness of the CDTA. For these reasons, BNL offered to demonstrate the CDTA for TTL as a no cost addition to the TTL lidar demonstration project. This report details the demonstration scenario and results.« less

49 CFR 230.64 - Leaks under lagging.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Leaks § 230.64 Leaks under lagging. The steam locomotive owner and/or operator shall take out of...

40 CFR Appendix M to Part 51 - Recommended Test Methods for State Implementation Plans

Code of Federal Regulations, 2014 CFR

2014-07-01

..., and after the run with the cyclone removed. The cyclone is removed before the post-test leak-check to.... 4.1.4.3 Post-Test Leak-Check. A leak-check is required at the conclusion of each sampling run... disturbing the collected sample and use the following procedure to conduct a post-test leak-check. 4.1.4.3.1...

40 CFR Appendix M to Part 51 - Recommended Test Methods for State Implementation Plans

Code of Federal Regulations, 2013 CFR

2013-07-01

..., and after the run with the cyclone removed. The cyclone is removed before the post-test leak-check to.... 4.1.4.3 Post-Test Leak-Check. A leak-check is required at the conclusion of each sampling run... disturbing the collected sample and use the following procedure to conduct a post-test leak-check. 4.1.4.3.1...

40 CFR Appendix M to Part 51 - Recommended Test Methods for State Implementation Plans

Code of Federal Regulations, 2011 CFR

2011-07-01

..., and after the run with the cyclone removed. The cyclone is removed before the post-test leak-check to.... 4.1.4.3 Post-Test Leak-Check. A leak-check is required at the conclusion of each sampling run... disturbing the collected sample and use the following procedure to conduct a post-test leak-check. 4.1.4.3.1...

40 CFR Appendix M to Part 51 - Recommended Test Methods for State Implementation Plans

Code of Federal Regulations, 2012 CFR

2012-07-01

..., and after the run with the cyclone removed. The cyclone is removed before the post-test leak-check to.... 4.1.4.3 Post-Test Leak-Check. A leak-check is required at the conclusion of each sampling run... disturbing the collected sample and use the following procedure to conduct a post-test leak-check. 4.1.4.3.1...

40 CFR 63.1088 - In what situations may I delay leak repair, and what actions must I take for delay of repair?

Code of Federal Regulations, 2013 CFR

2013-07-01

... process equipment associated with the leaking heat exchanger. You must document the basis for the... the repair as soon as practical. (3) Calculate the potential emissions from the leaking heat exchanger... substances) in the cooling water from the leaking heat exchanger by the flow rate of the cooling water from...

40 CFR 63.1088 - In what situations may I delay leak repair, and what actions must I take for delay of repair?

Code of Federal Regulations, 2012 CFR

2012-07-01

... process equipment associated with the leaking heat exchanger. You must document the basis for the... the repair as soon as practical. (3) Calculate the potential emissions from the leaking heat exchanger... substances) in the cooling water from the leaking heat exchanger by the flow rate of the cooling water from...

40 CFR 63.1088 - In what situations may I delay leak repair, and what actions must I take for delay of repair?

Code of Federal Regulations, 2014 CFR

2014-07-01

... process equipment associated with the leaking heat exchanger. You must document the basis for the... the repair as soon as practical. (3) Calculate the potential emissions from the leaking heat exchanger... substances) in the cooling water from the leaking heat exchanger by the flow rate of the cooling water from...

Leak detection using structure-borne noise

NASA Technical Reports Server (NTRS)

Holland, Stephen D. (Inventor); Roberts, Ronald A. (Inventor); Chimenti, Dale E. (Inventor)

2010-01-01

A method for detection and location of air leaks in a pressure vessel, such as a spacecraft, includes sensing structure-borne ultrasound waveforms associated with turbulence caused by a leak from a plurality of sensors and cross correlating the waveforms to determine existence and location of the leak. Different configurations of sensors and corresponding methods can be used. An apparatus for performing the methods is also provided.

Assessment of Remote Sensing Technologies for Location of Hydrogen and Helium Leaks

NASA Technical Reports Server (NTRS)

Sellar, R. Glenn; Wang, Danli

2000-01-01

The objective of this initial phase of this research effort is to: 1) Evaluate remote sensing technologies for location of leaks of gaseous molecular hydrogen (H2) and gaseous helium (He) in air, for space transportation applications; and 2) Develop a diffusion model that predicts concentration of H2 or He gas as a function of leak rate and distance from the leak.

10 CFR 35.2067 - Records of leaks tests and inventory of sealed sources and brachytherapy sources.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Records of leaks tests and inventory of sealed sources and... MATERIAL Records § 35.2067 Records of leaks tests and inventory of sealed sources and brachytherapy sources. (a) A licensee shall retain records of leak tests required by § 35.67(b) for 3 years. The records...

40 CFR 63.1088 - In what situations may I delay leak repair, and what actions must I take for delay of repair?

Code of Federal Regulations, 2010 CFR

2010-07-01

... process equipment associated with the leaking heat exchanger. You must document the basis for the... the repair as soon as practical. (3) Calculate the potential emissions from the leaking heat exchanger... substances) in the cooling water from the leaking heat exchanger by the flow rate of the cooling water from...

40 CFR 63.1088 - In what situations may I delay leak repair, and what actions must I take for delay of repair?

Code of Federal Regulations, 2011 CFR

2011-07-01

... process equipment associated with the leaking heat exchanger. You must document the basis for the... the repair as soon as practical. (3) Calculate the potential emissions from the leaking heat exchanger... substances) in the cooling water from the leaking heat exchanger by the flow rate of the cooling water from...

Short-interval repeat ground-based surveys of fugitive emissions from oil production facilities in the Bakken

NASA Astrophysics Data System (ADS)

Englander, J. G.; Wang, J.; Lebel, E.; Brandt, A. R.; Jackson, R. B.

2016-12-01

There has been a growing body of research focused on fugitive emissions from oil and gas production. Some studies are bottom-up, component-level studies of individual leaks, while others use atmospheric flux quantification to estimate overall leakage [1]. These studies represent static views of the emissions from a particular region or piece of equipment. There have not (as of yet) been studies examining how the leaks in a facility change over time. Also, challenges have arisen due to study designs that primarily rely on operator cooperation, raising the potential of participation bias in samples taken. This study investigates the persistence of leaking wellpads in the Bakken formation over time, utilizing ground-based observations with an optical gas imaging camera (FLIR GF320). This study examines - without operator foreknowledge - operations which are visible from public roads. This study is broken up into two phases: Phase A included seventy well pads observed over seven separate visits (15, 30, 45, 60, 75, 180, 365 days) where well sites were selected using prior observations to include a higher proportion of leaking wells than across the population overall. Phase B includes sixty-two randomly selected well pads observed over six visits (15, 30, 45, 60, 75, 180 days). This study examines the dynamics between leaking and non-leaking sites over time by comparing the observed presence (or absence) of leaks in a Monte Carlo simulation to a random leak distribution [2]. Even after 180 days, the number of well pads that persisted as either leaking or non-leaking were more than 2σ away from that expected using a random distribution of leaks. This indicates that the mitigation of previously leaking wells could have a significant impact in the reduction of fugitive emissions through enabling persistent improvements in leakage behavior. [1] D. R. Lyon et al. "Aerial surveys of elevated hydrocarbon emissions from oil and gas production sites," Environ. Sci. Technol., p. acs.est.6b00705, Apr. 2016. [2] J. Peischl et al. "Quantifying atmospheric methane emissions from oil and natural gas production in the Bakken shale region of North Dakota," J. Geophys. Res. Atmos., May 2016.

Usefulness of high-density barium for detection of leaks after esophagogastrectomy, total gastrectomy, and total laryngectomy.

PubMed

Swanson, Jonathan O; Levine, Marc S; Redfern, Regina O; Rubesin, Stephen E

2003-08-01

The purpose of this study was to determine the usefulness of a high-density (250% weight/volume) barium compared with a water-soluble contrast agent for the detection of esophageal leaks in patients who had undergone esophagogastrectomy, total gastrectomy, or total laryngectomy. A search of our radiology database from 1998 to 2001 revealed 46 eligible radiographic studies performed using a water-soluble contrast agent alone or a water-soluble contrast agent followed by barium that showed leaks in patients who had undergone esophagogastrectomy, total gastrectomy, or total laryngectomy. The images were reviewed to determine the morphology of the leaks (i.e., blind-ending tracks, sealed-off collections, or free extravasation of contrast material). Medical records were also reviewed to determine whether detection of the leaks seen on the radiographic studies affected patient management. Of the 46 leaks seen on radiographic studies, 23 (50%) were detected with a water-soluble contrast agent and 23 (50%) were detected only with high-density barium. Of the 23 leaks visualized with water-soluble contrast media, six (26%) were characterized by blind-ending tracks, 14 (61%) by sealed-off collections, and three (13%) by free extravasation of contrast material into the mediastinum or neck. Of the 23 leaks visualized only with high-density barium, 19 (83%) were characterized by blind-ending tracks and four (17%) by sealed-off collections. Thus, leaks detected only on images obtained with high-density barium were significantly more likely to be characterized by blind-ending tracks than those detected on images obtained with a water-soluble contrast agent (p = 0.0007). Of the 33 patients with clinical follow-up, the findings seen on these imaging studies affected management in 12 (86%) of 14 patients with leaks depicted by water-soluble contrast media and in 10 (53%) of 19 with leaks depicted only by high-density barium. Our findings support the use of high-density barium as part of the routine postoperative radiographic examination when no leaks are detected on images obtained with a water-soluble contrast agent.

Smokestack leak in central serous chorioretinopathy.

PubMed

Bujarborua, Dhiren; Nagpal, Pran N; Deka, Manab

2010-03-01

To study the demography, various morphological patterns and fluid dynamics of the smokestack leak by fluorescein angiography (FA) in central serous chorioretinopathy (CSC). Part I (clinical): review of the medical records and angiographic documents of 69 consecutive cases of CSC with smokestack leak. Part II (experimental): documentation of the movement of various concentrations of fluorescein dye due to convection currents in a laboratory model that roughly represents a closed chamber similar to that of CSC in human eyes. The clinical study (Part I) revealed that 14.40% of 479 consecutive cases had smokestack leak, of which 70% occurred in first acute episode (p-value: <0.001), 27.14% in acute recurrent episodes (50% fresh leak) and 2.85% in chronic stage. Patients were predominantly male (84.05%) with a median age of 34.00 +/- 8.14 years. The median symptom duration excluding the chronic cases was 15 +/- 34.28 days. This type of leak was mostly (48.57%) seen in medium-sized CSC, and the majority were in the parafoveal superonasal quadrant (31.42%). The ascending type of leak was predominant (94.28%). In four eyes, an atypical pattern and in two eyes more than one smokestack leak were seen within the same detached area. The experimental study (Part II) demonstrated that fluid containing a low concentration of fluorescein ascended due to convection currents, whereas highly concentrated dye descended. The clinical study revealed smokestack leaks to be significantly more common in a primary acute episode, and they usually develop in the early part of the acute phase of the disease (average duration 15 +/- 34.28 days). Rarely, this type of leak can occur in the chronic stage, and multiple leaks may develop in the same detached space. The various patterns of dye movement due to convection currents in the experimental model resembled the dye movement in certain cases of CSC of the present series. The experimental study also hinted at the probability of drainage of unbound fluorescein molecules along with protein-laden heavy fluid in downward spread of the leak.

Intraoperative air leak measured after lobectomy is associated with postoperative duration of air leak.

PubMed

Brunelli, Alessandro; Salati, Michele; Pompili, Cecilia; Gentili, Paolo; Sabbatini, Armando

2017-11-01

To verify the association between the air leak objectively measured intraoperatively (IAL) using the ventilator and the air leak duration after pulmonary lobectomy. Prospective analysis on 111 patients submitted to pulmonary lobectomy (33 by video-assisted thoracic surgery). After resection, objective assessment of air leak (in milliliter per minute) was performed before closure of the chest by measuring the difference between a fixed inspired and expired volume, using a tidal volume of 8 ml/kg, a respiratory rate of 10 and a positive-end expiratory pressure of 5 cmH2O. A multivariable analysis was performed for identifying factors associated with duration of postoperative air leak. Average IAL was 158 ml/min (range 0-1500 ml/min). The best cut-off (receiver-operating characteristics analysis) associated with air leak longer than 5 days was 500 ml/min. Nine patients had IAL >500 ml/min (8%). They had a longer duration of postoperative air leak compared with those with a lower IAL (mean values, 10.1 days, SD 8.8 vs 1.5 days, SD 4.9 P < 0.001). The following variables remained associated with days of air leak duration after multivariable regression: left side resection (P = 0.018), upper site resection (P = 0.031) and IAL >500 ml/min (P < 0.001). The following equation estimating the days of air leak duration was generated: 1.7 + 2.4 × left side + 2.2 × upper site + 8.8 × IAL >500. The air leak measurement using the ventilator parameters after lung resection may assist in estimating the risk of postoperative prolonged air leak. An IAL > 500 ml/min may warrant the use of intraoperative preventative measures, particularly after video-assisted thoracic surgery lobectomy where a submersion test is often unreliable. © 2017 European Society of Cardiology and European Atherosclerosis Association. All rights reserved. For permissions please email: journals.permissions@oup.com.

Risk Factors for Gastrointestinal Leak after Bariatric Surgery: MBASQIP Analysis.

PubMed

Alizadeh, Reza Fazl; Li, Shiri; Inaba, Colette; Penalosa, Patrick; Hinojosa, Marcelo W; Smith, Brian R; Stamos, Michael J; Nguyen, Ninh T

2018-03-30

Gastrointestinal leak remains one of the most dreaded complications in bariatric surgery. We aimed to evaluate risk factors and the impact of common perioperative interventions on the development of leak in patients who underwent laparoscopic bariatric surgery. Using the 2015 database of accredited centers, data were analyzed for patients who underwent laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass (LRYGB). Emergent, revisional, and converted cases were excluded. Multivariate logistic regression was used to analyze risk factors for leak, including provocative testing of anastomosis, surgical drain placement, and use of postoperative swallow study. Data from 133,478 patients who underwent laparoscopic sleeve gastrectomy (n = 92,495 [69.3%]) and LRYGB (n = 40,983 [30.7%]) were analyzed. Overall leak rate was 0.7% (938 of 133,478). Factors associated with increased risk for leak were oxygen dependency (adjusted odds ratio [AOR] 1.97), hypoalbuminemia (AOR 1.66), sleep apnea (AOR 1.52), hypertension (AOR 1.36), and diabetes (AOR 1.18). Compared with LRYGB, laparoscopic sleeve gastrectomy was associated with a lower risk of leak (AOR 0.52; 95% CI 0.44 to 0.61; p < 0.01). Intraoperative provocative test was performed in 81.9% of cases and the leak rate was higher in patients with vs without a provocative test (0.8% vs 0.4%, respectively; p < 0.01). A surgical drain was placed in 24.5% of cases and the leak rate was higher in patients with vs without a surgical drain placed (1.6% vs 0.4%, respectively; p < 0.01). A swallow study was performed in 41% of cases and the leak rate was similar between patients with vs without swallow study (0.7% vs 0.7%; p = 0.50). The overall rate of gastrointestinal leak in bariatric surgery is low. Certain preoperative factors, procedural type (LRYGB), and interventions (intraoperative provocative test and surgical drain placement) were associated with a higher risk for leaks. Copyright © 2018 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Use of a sealant to prevent prolonged air leaks after lung resection: a prospective randomized study.

PubMed

Lequaglie, Cosimo; Giudice, Gabriella; Marasco, Rita; Morte, Aniello Della; Gallo, Massimiliano

2012-10-08

Pulmonary air leaks are common complications of lung resection and result in prolonged hospital stays and increased costs. The purpose of this study was to investigate whether, compared with standard care, the use of a synthetic polyethylene glycol matrix (CoSeal®) could reduce air leaks detected by means of a digital chest drain system (DigiVent™), in patients undergoing lung resection (sutures and/or staples alone). Patients who intraoperatively showed moderate or severe air leaks (evaluated by water submersion tests) were intraoperatively randomized to receive just sutures/staples (control group) or sutures/staples plus CoSeal® (sealant group). Differences among the groups in terms of air leaks, prolonged air leaks, time to chest tube removal, length of hospital stay and related costs were assessed. In total, 216 lung resection patients completed the study. Nineteen patients (18.1%) in the control group and 12 (10.8%) patients in the sealant group experienced postoperative air leaks, while a prolonged air leak was recorded in 11.4% (n=12) of patients in the control group and 2.7% (n=3) of patients in the sealant group. The difference in the incidence of air leaks and prolonged air leaks between the two groups was statistically significant (p=0.0002 and p=0.0013). The mean length of hospital stay was significantly shorter in the sealant group (4 days) than the control group (8 days) (p=0.0001). We also observed lower costs in the sealant group than the control group. The use of CoSeal® may decrease the occurrence and severity of postoperative air leaks after lung resection and is associated with shorter hospital stay. Not registered. The trial was approved by the Institutional Review Board of the IRCCS-CROB Basilicata Regional Cancer Institute, Rionero in Vulture, Italy.

A prospective randomized trial comparing homologous and autologous fibrin sealants for the control of alveolar air leak.

PubMed

Kılıç, Burcu; Erşen, Ezel; Demirkaya, Ahmet; Kara, H Volkan; Alizade, Nurlan; İşcan, Mehlika; Kaynak, Kamil; Turna, Akif

2017-09-01

Postoperative air leak is a common complication seen after pulmonary resection. It is a significant reason of morbidity and also leads to greater hospital cost owing to prolonged length of stay. The purpose of this study is to compare homologous sealant with autologous one to prevent air leak following pulmonary resection. A total of 57 patients aged between 20 and 79 (mean age: 54.36) who underwent pulmonary resection other than pneumonectomy (lobar or sublobar resections) were analyzed. There were 47 males (83%) and 10 females (17%). Patients who intraoperatively had air leaks were randomized to receive homologous (Tisseel; n=28) or autologous (Vivostat; n=29) fibrin sealant. Differences among groups in terms of air leak, prolonged air leak, hospital stay, amount of air leak were analyzed. Indications for surgery were primary lung cancer in 42 patients (71.9%), secondary malignancy in 5 patients (8.8%), and benign disease in 10 patients (17.5%). Lobectomy was performed in 40 patients (70.2%), whereas 17 patients (29.8%) had wedge resection. Thirteen (46.4%) patients developed complications in patients receiving homologous sealant while 11 (38.0%) patients had complication in autologous sealant group (P=0.711). Median duration of air leak was 3 days in two groups. Time to intercostal drain removal was 3.39 and 3.38 days in homologous and autologous sealant group respectively (P=0.978). Mean hospital stay was 5.5 days in patients receiving homologous sealant whereas it was 5.0 days in patients who had autologous agent (P=0.140). There were no significant differences between groups in terms of measured maximum air leak (P=0.823) and mean air leak (P=0.186). There was no significant difference in the incidence of complications between two groups (P=0.711). Autologous and heterologous fibrin sealants are safe and acts similarly in terms of air leak and hospital stay in patients who had resectional surgery.

Sieving characteristics of cytokine- and peroxide-induced epithelial barrier leak: Inhibition by berberine

PubMed Central

DiGuilio, Katherine M; Mercogliano, Christina M; Born, Jillian; Ferraro, Brendan; To, Julie; Mixson, Brittany; Smith, Allison; Valenzano, Mary Carmen; Mullin, James M

2016-01-01

AIM: To study whether the inflammatory bowel disease (IBD) colon which exhibits varying severity and cytokine levels across its mucosa create varying types of transepithelial leak. METHODS: We examined the effects of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-1-β (IL1β) and hydrogen peroxide (H2O2) - singly and in combinations - on barrier function of CACO-2 cell layers. Our focus was on the type (not simply the magnitude) of transepithelial leak generated by these agents as measured by transepithelial electrical resistance (TER) and transepithelial flux of 14C-D-mannitol, 3H-Lactulose and 14C-Polyethylene glycol as radiolabeled probe molecules. The isoquinoline alkaloid, berberine, was then examined for its ability to reduce specific types of transepithelial leak. RESULTS: Exposure to TNF-α alone (200 ng/mL; 48 h) induced a 50% decrease in TER, i.e., increased leak of Na+ and Cl- - with only a marginal but statistically significant increase in transepithelial leak of 14C-mannitol (Jm). Exposure to TNF-α + IFN-γ (200 ng/mL; 48 h) + IL1β (50 ng/mL; 48 h) did not increase the TER change (from TNF-α alone), but there was now a 100% increase in Jm. There however was no increase in transepithelial leak of two larger probe molecules, 3H-lactulose and 14C-polyethylene glycol (PEG). However, exposure to TNF-α + IFN-γ + IL1β followed by a 5 h exposure to 2 mmol/L H2O2 resulted in a 500% increase in 14C-PEG leak as well as leak to the luminal mitogen, epidermal growth factor. CONCLUSION: This model of graded transepithelial leak is useful in evaluating therapeutic agents reducing IBD morbidity by reducing barrier leak to various luminal substances. PMID:27190695

Impact of the Surgical Experience on Leak Rate After Laparoscopic Sleeve Gastrectomy.

PubMed

Noel, Patrick; Nedelcu, Marius; Gagner, Michel

2016-08-01

Laparoscopic sleeve gastrectomy (LSG) has become one of the most commonly performed bariatric procedures, largely due to several advantages it carries over more complex bariatric procedures. LSG is generally considered a straightforward procedure, but one of the major concerns is a staple line leak. The objectives of this study are to evaluate the correlation between surgeon's experience and leak rate and to assess the different risk factors for developing a gastric leak after LSG. Private hospital, France. The analysis of a single surgeon's yearly leak rate since the introduction of LSG for possible risk factors was done. A total of 2012 LSGs were performed in between September, 2005 and December, 2014. Twenty cases (1 %) of gastric leak were recorded. Of these, 17 patients were women (94.4 %) with a mean age of 39.4 years (range 22-61) and mean body mass index (BMI) 41.2 kg/m(2) (range 34.8-57.1). On a yearly basis, the leak rate was 4.8 % (2006), 5.7 % (2007), 0 (2008), 2.6 % (2009), 2 % (2010), 0.8 % (2011), 0.6 % (2012), 0.2 % (2013), and 0 (2014). In the first 1000 cases (group A), there were 18 cases of gastric leak and in the last 1000 cases, there were 800 with GORE® SEAMGUARD® Bioabsorbable Staple Line Reinforcement (group B) 2 cases of gastric leak (p = 0.009). A revisional LSG, 395 patients after gastric banding and 61 patients re-sleeve gastrectomy, was performed in 456 cases (22.7 %). There were 3 cases of leak (0.65 %). There were two deaths. LSG can be performed with a low complication rate. This large series of a single surgeon's experience demonstrated that the leak rate after LSG could be significantly decreased over time with changes in techniques.

Prognostic Factors and Significance of Gastrointestinal Leak After Cytoreductive Surgery (CRS) with Heated Intraperitoneal Chemotherapy (HIPEC).

PubMed

Chouliaras, Konstantinos; Levine, Edward A; Fino, Nora; Shen, Perry; Votanopoulos, Konstantinos I

2017-04-01

Gastrointestinal leak (GIL) after cytoreductive surgery with heated intraperitoneal chemotherapy (CRS/HIPEC) is associated with significant morbidity and mortality. This study aimed to identify GIL prognostic factors and its impact on overall survival. A retrospective analysis of a prospectively maintained database comprising 1270 CRS/HIPEC procedures was performed. Type of GIL, functional and resection status, morbidity, mortality, and survival were reviewed. Gastrointestinal leaks were identified in 8.7% (110/1270) of CRS/HIPEC procedures, including 53 anastomotic leaks (4.2%), 53 hollow viscus perforations (4.2%), and four leaks at unknown sites. The multivariate predictors of leak were Eastern Cooperative Oncology Group (ECOG) functional status (ECOG 1 vs. 0: odds ratio [OR] 2.12, p = 0.009; ECOG 2 vs. 0: OR 2.90, p = 0.004), and number of anastomoses (OR 5.34; p < 0.0001). The in-hospital mortality rate for the GIL cohort was 21.8% (24/110), with a 72% (80/110) reoperation rate. The leak cohort had a higher major morbidity rate (88.3 vs. 23.3%; p < 0.0001), a longer hospital stay (39.0 vs. 9.9 days; p < 0.0001), and a longer intensive care unit (ICU) stay (7.7 vs. 1.7 days; p = 0.0003). After surgical mortality was excluded, the overall survival periods for the leak and no-leak patients with complete cytoreduction were respectively 1.5 and 4.98 years (p = 0.0001). Clinically significant decreases in survival were observed for all primary malignancies. Gastrointestinal leak after CRS/HIPEC is a source of significant mortality, with a decrease in overall survival even after complete CRS. Preoperative functional status and number of anastomoses are predictors of leak for CRS/HIPEC patients.

Intrapleural instillation of autologous blood for persistent air leak in spontaneous pneumothorax in patients with advanced chronic obstructive pulmonary disease.

PubMed

Cao, Guo qiang; Kang, Jun; Wang, Fangwen; Wang, Hucheng

2012-05-01

We evaluated the safety and efficacy of increasing doses of autologous blood patch pleurodesis in treating persistent air leaks in patients with advanced chronic obstructive pulmonary disease (COPD). Forty-four patients with COPD and spontaneous pneumothorax (SP) on the 7th day after intercostal tube drainage were randomly assigned to 4 groups, with 11 patients in each group. Groups A, B, and C were given increasing doses of autologous blood--ie, 0.5 mL/kg, 1 mL/kg, 2 mL/kg, respectively--whereas group D was given 1 mL/kg normal saline only. The procedure was repeated if the air leak persisted on postoperative days 9 and 11. Patients in group D crossed over and received autologous blood as in group B if the air leak was still present on the 13th postoperative day. No patient died in the study. The air leak was sealed by the 13th postoperative day only in patients with air leaks smaller than size 3. Air leaks were classified as 0 to 3 [12], ie, size 0=no air leak; size 1=air leak on vigorous coughing only; size 2=small continuous air leak on gentle respiration; and size 3=large continuous air leak on gentle respiration. The success rates by the 13th postoperative day in groups A, B, C, and D were 27%, 82%, 82%, and 9%, respectively. The success rate (82%) was significantly higher in groups B and C than in group A (p=0.003) and D (p>0.01). Using autologous blood to treat secondary spontaneous pneumothorax (SSP) in patients with advanced COPD is easy, safe, and effective. The dose of blood required for autologous blood patch pleurodesis should be dependent on the body weight, and 1 mL/kg blood may be efficient. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

A prospective randomized trial comparing homologous and autologous fibrin sealants for the control of alveolar air leak

PubMed Central

Erşen, Ezel; Demirkaya, Ahmet; Kara, H. Volkan; Alizade, Nurlan; İşcan, Mehlika; Kaynak, Kamil; Turna, Akif

2017-01-01

Background Postoperative air leak is a common complication seen after pulmonary resection. It is a significant reason of morbidity and also leads to greater hospital cost owing to prolonged length of stay. The purpose of this study is to compare homologous sealant with autologous one to prevent air leak following pulmonary resection. Methods A total of 57 patients aged between 20 and 79 (mean age: 54.36) who underwent pulmonary resection other than pneumonectomy (lobar or sublobar resections) were analyzed. There were 47 males (83%) and 10 females (17%). Patients who intraoperatively had air leaks were randomized to receive homologous (Tisseel; n=28) or autologous (Vivostat; n=29) fibrin sealant. Differences among groups in terms of air leak, prolonged air leak, hospital stay, amount of air leak were analyzed. Results Indications for surgery were primary lung cancer in 42 patients (71.9%), secondary malignancy in 5 patients (8.8%), and benign disease in 10 patients (17.5%). Lobectomy was performed in 40 patients (70.2%), whereas 17 patients (29.8%) had wedge resection. Thirteen (46.4%) patients developed complications in patients receiving homologous sealant while 11 (38.0%) patients had complication in autologous sealant group (P=0.711). Median duration of air leak was 3 days in two groups. Time to intercostal drain removal was 3.39 and 3.38 days in homologous and autologous sealant group respectively (P=0.978). Mean hospital stay was 5.5 days in patients receiving homologous sealant whereas it was 5.0 days in patients who had autologous agent (P=0.140). There were no significant differences between groups in terms of measured maximum air leak (P=0.823) and mean air leak (P=0.186). There was no significant difference in the incidence of complications between two groups (P=0.711). Conclusions Autologous and heterologous fibrin sealants are safe and acts similarly in terms of air leak and hospital stay in patients who had resectional surgery. PMID:29221263

Sodium leak channel, non-selective contributes to the leak current in human myometrial smooth muscle cells from pregnant women.

PubMed

Reinl, Erin L; Cabeza, Rafael; Gregory, Ismail A; Cahill, Alison G; England, Sarah K

2015-10-01

Uterine contractions are tightly regulated by the electrical activity of myometrial smooth muscle cells (MSMCs). These cells require a depolarizing current to initiate Ca(2+) influx and induce contraction. Cationic leak channels, which permit a steady flow of cations into a cell, are known to cause membrane depolarization in many tissue types. Previously, a Gd(3+)-sensitive, Na(+)-dependent leak current was identified in the rat myometrium, but the presence of such a current in human MSMCs and the specific ion channel conducting this current was unknown. Here, we report the presence of a Na(+)-dependent leak current in human myometrium and demonstrate that the Na(+)-leak channel, NALCN, contributes to this current. We performed whole-cell voltage-clamp on fresh and cultured MSMCs from uterine biopsies of term, non-laboring women and isolated the leak currents by using Ca(2+) and K(+) channel blockers in the bath solution. Ohmic leak currents were identified in freshly isolated and cultured MSMCs with normalized conductances of 14.6 pS/pF and 10.0 pS/pF, respectively. The myometrial leak current was significantly reduced (P < 0.01) by treating cells with 10 μM Gd(3+) or by superfusing the cells with a Na(+)-free extracellular solution. Reverse transcriptase PCR and immunoblot analysis of uterine biopsies from term, non-laboring women revealed NALCN messenger RNA and protein expression in the myometrium. Notably, ∼90% knockdown of NALCN protein expression with lentivirus-delivered shRNA reduced the Gd(3+)-sensitive leak current density by 42% (P < 0.05). Our results reveal that NALCN, in part, generates the leak current in MSMCs and provide the basis for future research assessing NALCN as a potential molecular target for modulating uterine excitability. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Influence of preoperative radiation field on postoperative leak rates in esophageal cancer patients after trimodality therapy.

PubMed

Juloori, Aditya; Tucker, Susan L; Komaki, Ritsuko; Liao, Zhongxing; Correa, Arlene M; Swisher, Stephen G; Hofstetter, Wayne L; Lin, Steven H

2014-04-01

Postoperative morbidities, such as anastomotic leaks, are common after trimodality therapy (chemoradiation followed by surgery) for esophageal cancer. We investigated for factors associated with an increased incidence of anastomotic leaks. Data from 285 esophageal cancer patients treated from 2000 to 2011 with trimodality therapy were analyzed. Anastomotic location relative to preoperative radiation field was assessed using postoperative computed tomographic imaging. Logistic regression was used to evaluate for factors associated with any or clinically relevant (CR) (≥ grade 2) leaks. Overall anastomotic leak rate was 11% (31 of 285), and CR leak rate was 6% (17 of 285). Multivariable analysis identified body mass index (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.00-1.17; OR, 1.11, 95% CI, 1.01-1.22), three-field surgery (OR, 10.01; 95% CI, 3.83-26.21; OR, 4.83; 95% CI, 1.39-16.71), and within radiation field ("in-field") anastomosis (OR, 5.37; 95% CI, 2.21-13.04; OR, 8.63; 95% CI, 2.90-25.65) as independent predictors of both all grade and CR leaks, respectively. While patients with distal esophageal tumors and Ivor-Lewis surgery had the lowest incidence of all grade (6.5%) and CR leaks (4.2%), most of the leaks were associated with the anastomosis constructed within the field of radiation (in-field: 39% and 30% versus out-of-field: 2.6% and 1.0%, respectively, for total and CR leaks, p less than 0.0001, Fisher's exact test). Esophagogastric anastomosis placed within the preoperative radiation field was a very strong predictor for anastomotic leaks in esophageal cancer patients treated with trimodality therapy, among other factors. Surgical planning should include a critical evaluation of the preoperative radiation fields to ensure proper anastomotic placement after chemoradiation therapy.

Differential Impact of Anastomotic Leak in Patients With Stage IV Colonic or Rectal Cancer: A Nationwide Cohort Study.

PubMed

Nordholm-Carstensen, Andreas; Rolff, Hans Christian; Krarup, Peter-Martin

2017-05-01

Anastomotic leak has a negative impact on the prognosis of patients who undergo colorectal cancer resection. However, data on anastomotic leak are limited for stage IV colorectal cancers. The purpose of this study was to investigate the impact of anastomotic leak on survival and the decision to administer chemotherapy and/or metastasectomy after elective surgery for stage IV colorectal cancer. This was a nationwide, retrospective cohort study. Data were obtained from the Danish Colorectal Cancer Group, the Danish Pathology Registry, and the National Patient Registry. Patients who were diagnosed with stage IV colorectal cancer between 2009 and 2013 and underwent elective resection of their primary tumors were included. The primary outcome was all-cause mortality depending on the occurrence of anastomotic leak. Secondary outcomes were the administration of and time to adjuvant chemotherapy, metastasectomy rate, and risk factors for leak. Of the 774 patients with stage IV colorectal cancer who were included, 71 (9.2%) developed anastomotic leaks. Anastomotic leak had a significant impact on the long-term survival of patients with colon cancer (p = 0.04) but not on those with rectal cancer (p = 0.91). Anastomotic leak was followed by the decreased administration of adjuvant chemotherapy in patients with colon cancer (p = 0.007) but not in patients with rectal cancer (p = 0.47). Finally, anastomotic leak had a detrimental impact on metastasectomy rates after colon cancer but not on resection rates of rectal cancer. Retrospective data on the selection criteria for primary tumor resection and metastatic tumor load were unavailable. The impact of anastomotic leak on patients differed between stage IV colon and rectal cancers. Survival and eligibility to receive chemotherapy and metastasectomy differed between patients with colon and rectal cancers. When planning for primary tumor resection, these factors should be considered.

Fluid sampling device

NASA Technical Reports Server (NTRS)

Studenick, D. K. (Inventor)

1977-01-01

An inlet leak is described for sampling gases, more specifically, for selectively sampling multiple fluids. This fluid sampling device includes a support frame. A plurality of fluid inlet devices extend through the support frame and each of the fluid inlet devices include a longitudinal aperture. An opening device that is responsive to a control signal selectively opens the aperture to allow fluid passage. A closing device that is responsive to another control signal selectively closes the aperture for terminating further fluid flow.

REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures

National Institute of Standards and Technology Data Gateway

SRD 73 NIST REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures (PC database for purchase)   REFLEAK estimates composition changes of zeotropic mixtures in leak and recharge processes.

Investigation of the Leak Response of a Carbon-Fiber Laminate Loaded in Biaxial Tension

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Ratcliffe, James G.

2013-01-01

Designers of pressurized structures have been reluctant to use composite materials because of concerns over leakage. Biaxial stress states are expected to be the worst-case loading condition for allowing leakage to occur through microcracks. To investigate the leakage behavior under in-plane biaxial loading, a cruciform composite specimen was designed that would have a relatively large test section with a uniform 1:1 biaxial loading ratio. A 7.6-cm-square test section was desired for future investigations of the leakage response as a result of impact damage. Many iterations of the cruciform specimen were evaluated using finite element analysis to reduce stress concentrations and maximize the size of the uniform biaxial strain field. The final design allowed the specimen to go to relatively high biaxial strain levels without incurring damage away from the test section. The specimen was designed and manufactured using carbon/epoxy fabric with a four-ply-thick, quasi-isotropic, central test section. Initial validation and testing were performed on a specimen without impact damage. The specimen was tested to maximum biaxial strains of approximately 4500micro epsilon without apparent damage. A leak measurement system containing a pressurized cavity was clamped to the test section and used to measure the flow rate through the specimen. The leakage behavior of the specimen was investigated for pressure differences up to 172 kPa

Orai3 channel is the 2-APB-induced endoplasmic reticulum calcium leak.

PubMed

Leon-Aparicio, Daniel; Pacheco, Jonathan; Chavez-Reyes, Jesus; Galindo, Jose M; Valdes, Jesus; Vaca, Luis; Guerrero-Hernandez, Agustin

2017-07-01

We have studied in HeLa cells the molecular nature of the 2-APB induced ER Ca 2+ leak using synthetic Ca 2+ indicators that report changes in both the cytoplasmic ([Ca 2+ ] i ) and the luminal ER ([Ca 2+ ] ER ) Ca 2+ concentrations. We have tested the hypothesis that Orai channels participate in the 2-APB-induced ER Ca 2+ leak that was characterized in the companion paper. The expression of the dominant negative Orai1 E106A mutant, which has been reported to block the activity of all three types of Orai channels, inhibited the effect of 2-APB on the [Ca 2+ ] ER but did not decrease the ER Ca 2+ leak after thapsigargin (TG). Orai3 channel, but neither Orai1 nor Orai2, colocalizes with expressed IP 3 R and only Orai3 channel supported the 2-APB-induced ER Ca 2+ leak, while Orai1 and Orai2 inhibited this type of ER Ca 2+ leak. Decreasing the expression of Orai3 inhibited the 2-APB-induced ER Ca 2+ leak but did not modify the ER Ca 2+ leak revealed by inhibition of SERCA pumps with TG. However, reducing the expression of Orai3 channel resulted in larger [Ca 2+ ] i response after TG but only when the ER store had been overloaded with Ca 2+ by eliminating the acidic internal Ca 2+ store with bafilomycin. These data suggest that Orai3 channel does not participate in the TG-revealed ER Ca 2+ leak but forms an ER Ca 2+ leak channel that is limiting the overloading with Ca 2+ of the ER store. Copyright © 2017 Elsevier Ltd. All rights reserved.