46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

The importance of valve alignment in determining the pressure/flow characteristics of differential pressure shunt valves with anti-gravity devices.

PubMed

Francel, P C; Stevens, F A; Tompkins, P; Pollay, M

2001-02-01

The proper functioning of shunt valves in vivo is dependent on many factors, including the valve itself, the anti-siphon device or ASD (if included), patency of inlet and outlet tubing, and location of the valve. One important, but sometimes overlooked, consideration in valve function is the valve location relative to the tip of the ventricular inlet catheter. As with any pressure measurement, the zero or reference position is an important concept. In the case of shunt valves, the position of the proximal inlet catheter tip is fixed and therefore serves as the reference point for all pressure measurements. This study was conducted to document the importance of this relationship for the pressure/flow characteristics of the shunt valve. We bench-tested differential pressure valves (with integral anti-gravity devices; AGDs) from three manufacturers. Valves were connected to an "infinite" reservoir, and the starting head pressure for each was determined from product inserts. The inlet catheter tip was fixed at this position, and the valve body was moved in relation to the inlet catheter tip. Outflow rates were determined gravimetrically for positions varying between 4 cm above and 8 cm below the inlet catheter tip. All differential pressure valves utilized in this study that contained AGDs showed significant increases in outflow rate as the valve body was moved incrementally below the level of the inlet catheter tip. To allow functioning as a zero-hydrostatic pressure differential pressure valve, the AGD and the inlet catheter tip should be aligned at the same horizontal level.

Development of high pressure-high vacuum-high conductance piston valve for gas-filled radiation detectors

NASA Astrophysics Data System (ADS)

Prasad, D. N.; Ayyappan, R.; Kamble, L. P.; Singh, J. P.; Muralikrishna, L. V.; Alex, M.; Balagi, V.; Mukhopadhyay, P. K.

2008-05-01

Gas-filled radiation detectors need gas filling at pressures that range from few cms of mercury to as high as 25kg/cm2 at room temperature. Before gas-filling these detectors require evacuation to a vacuum of the order of ~1 × 10-5 mbar. For these operations of evacuation and gas filling a system consisting of a vacuum pump with a high vacuum gauge, gas cylinder with a pressure gauge and a valve is used. The valve has to meet the three requirements of compatibility with high-pressure and high vacuum and high conductance. A piston valve suitable for the evacuation and gas filling of radiation detectors has been designed and fabricated to meet the above requirements. The stainless steel body (80mm×160mm overall dimensions) valve with a piston arrangement has a 1/2 inch inlet/outlet opening, neoprene/viton O-ring at piston face & diameter for sealing and a knob for opening and closing the valve. The piston movement mechanism is designed to have minimum wear of sealing O-rings. The valve has been hydrostatic pressure tested up to 75bars and has Helium leak rate of less than 9.6×10-9 m bar ltr/sec in vacuum mode and 2×10-7 mbar ltr/sec in pressure mode. As compared to a commercial diaphragm valve, which needed 3 hours to evacuate a 7 litre chamber to 2.5×10-5 mbar, the new valve achieved vacuum 7.4×10-6mbar in the same time under the same conditions.

Statistical Performance Evaluation Of Soft Seat Pressure Relief Valves

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

Harris, Stephen P.; Gross, Robert E.

2013-03-26

Risk-based inspection methods enable estimation of the probability of failure on demand for spring-operated pressure relief valves at the United States Department of Energy's Savannah River Site in Aiken, South Carolina. This paper presents a statistical performance evaluation of soft seat spring operated pressure relief valves. These pressure relief valves are typically smaller and of lower cost than hard seat (metal to metal) pressure relief valves and can provide substantial cost savings in fluid service applications (air, gas, liquid, and steam) providing that probability of failure on demand (the probability that the pressure relief valve fails to perform its intendedmore » safety function during a potentially dangerous over pressurization) is at least as good as that for hard seat valves. The research in this paper shows that the proportion of soft seat spring operated pressure relief valves failing is the same or less than that of hard seat valves, and that for failed valves, soft seat valves typically have failure ratios of proof test pressure to set pressure less than that of hard seat valves.« less

Globe stability during simulated vitrectomy with valved and non-valved trocar cannulas

PubMed Central

Abulon, Dina Joy; Charles, Martin; Charles, Daniel E

2015-01-01

Purpose To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP), fluid leakage, and vitreous incarceration during simulated vitrectomy. Methods Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved trocar cannulas. The models were filled with air and IOP was measured. Similar procedures were followed for 36 acrylic eyes filled with saline solution. Vitreous incarceration was analyzed in eleven rabbit and twelve porcine cadaver eyes. Results In the air-filled model, IOP loss was 89%–94% when two non-valved cannulas were unoccupied versus 1%–5% when two valved cannulas were unoccupied. In the fluid-filled model, with non-valved cannulas, IOP dropped while fluid leaked from the open ports. With two open ports, the IOP dropped to 20%–30% of set infusion pressure, regardless of infusion pressure and IOP compensation. The IOP was maintained in valved cannulas when one or two ports were left open, regardless of IOP compensation settings. There was no or minimal fluid leakage through open ports at any infusion pressure. Direct microscopic analysis of rabbit eyes showed that vitreous incarceration was significantly greater with 23-gauge non-valved than valved cannulas (P<0.005), and endoscopy of porcine eyes showed that vitreous incarceration was significantly greater with 23-gauge (P<0.05) and 27-gauge (P<0.05) non-valved cannulas. External observation of rabbit eyes showed vitreous prolapse through non-valved, but not valved, cannulas. Conclusion Valved cannulas surpassed non-valved cannulas in maintaining IOP, preventing fluid leakage, and reducing vitreous incarceration during simulated vitrectomy. PMID:26445520

Locking apparatus for gate valves

DOEpatents

Fabyan, J.; Williams, C.W.

A locking apparatus for fluid operated valves having a piston connected to the valve actuator which moves in response to applied pressure within a cylinder housing having a cylinder head, a catch block is secured to the piston, and the cylinder head incorporates a catch pin. Pressure applied to the cylinder to open the valve moves the piston adjacent to the cylinder head where the catch pin automatically engages the catch block preventing further movement of the piston or premature closure of the valve. Application of pressure to the cylinder to close the valve, retracts the catch pin, allowing the valve to close. Included are one or more selector valves, for selecting pressure application to other apparatus depending on the gate valve position, open or closed, protecting such apparatus from damage due to premature closing caused by pressure loss or operational error.

Slow opening valve. [valve design for shuttle portable oxygen system

NASA Technical Reports Server (NTRS)

Drapeau, D. F. (Inventor)

1984-01-01

A valve control is described having a valve body with an actuator stem and a rotating handle connected to the actuator stem by a differential drive mechanism which, during uniform movement of the handle in one direction, initially opens the valve at a relatively slow rate and, thereafter, complete the valve movement at a substantially faster rate. A series of stop rings are received about the body in frictional abutting relationship and serially rotated by the handle to uniformly resist handle movement independently of the extent of handle movement.

Mitral Valve Stenosis after Open Repair Surgery for Non-rheumatic Mitral Valve Regurgitation: A Review.

PubMed

Shabsigh, Muhammad; Lawrence, Cassidy; Rosero-Britton, Byron R; Kumar, Nicolas; Kimura, Satoshi; Durda, Michael Andrew; Essandoh, Michael

2016-01-01

Mitral stenosis (MS) after mitral valve (MV) repair is a slowly progressive condition, usually detected many years after the index MV surgery. It is defined as a mean transmitral pressure gradient (TMPG) >5 mmHg or a mitral valve area (MVA) <1.5 cm(2). Pannus formation around the mitral annulus or extending to the mitral leaflets is suggested as the main mechanism for developing delayed MS after MV repair. On the other hand, early stenosis is thought to be a direct result of an undersized annuloplasty ring. Furthermore, in MS following ischemic mitral regurgitation (MR) repair, subvalvular tethering is the hypothesized pathophysiology. MS after MV repair has an incidence of 9-54%. Several factors have been associated with a higher risk for developing MS after MV repair, including the use of flexible Duran annuloplasty rings versus rigid Carpentier-Edwards rings, complete annuloplasty rings versus partial bands, small versus large anterior leaflet opening angle, and anterior leaflet tip opening length. Intraoperative echocardiography can measure the anterior leaflet opening angle, the anterior leaflet tip opening dimension, the MVA and the mean TMPG, and may help identify patients at risk for developing MS after MV repair.

Mitral Valve Stenosis after Open Repair Surgery for Non-rheumatic Mitral Valve Regurgitation: A Review

PubMed Central

Shabsigh, Muhammad; Lawrence, Cassidy; Rosero-Britton, Byron R.; Kumar, Nicolas; Kimura, Satoshi; Durda, Michael Andrew; Essandoh, Michael

2016-01-01

Mitral stenosis (MS) after mitral valve (MV) repair is a slowly progressive condition, usually detected many years after the index MV surgery. It is defined as a mean transmitral pressure gradient (TMPG) >5 mmHg or a mitral valve area (MVA) <1.5 cm2. Pannus formation around the mitral annulus or extending to the mitral leaflets is suggested as the main mechanism for developing delayed MS after MV repair. On the other hand, early stenosis is thought to be a direct result of an undersized annuloplasty ring. Furthermore, in MS following ischemic mitral regurgitation (MR) repair, subvalvular tethering is the hypothesized pathophysiology. MS after MV repair has an incidence of 9–54%. Several factors have been associated with a higher risk for developing MS after MV repair, including the use of flexible Duran annuloplasty rings versus rigid Carpentier–Edwards rings, complete annuloplasty rings versus partial bands, small versus large anterior leaflet opening angle, and anterior leaflet tip opening length. Intraoperative echocardiography can measure the anterior leaflet opening angle, the anterior leaflet tip opening dimension, the MVA and the mean TMPG, and may help identify patients at risk for developing MS after MV repair. PMID:27148540

Nonlinear pressure-flow relationships for passive microfluidic valves.

PubMed

Seker, Erkin; Leslie, Daniel C; Haj-Hariri, Hossein; Landers, James P; Utz, Marcel; Begley, Matthew R

2009-09-21

An analytical solution is presented for the nonlinear pressure-flow relationship of deformable passive valves, which are formed by bonding a deformable film over etched channels separated by a weir. A fluidic pathway connecting the channels is opened when the upstream pressure creates a tunnel along a predefined narrow strip where the film is not bonded to the weir. When the width of the strip is comparable to the inlet channel width, the predicted closed-form pressure-flow rate relationship is in excellent agreement with experiments, which determine pressures by measuring film deflections for prescribed flow rates. The validated closed-form models involve no fitting parameters, and provide the foundation to design passive diodes with specific nonlinear pressure-flow characteristics.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

PubMed Central

Schipke, Kimberly J.; Filip To, S. D.; Warnock, James N.

2011-01-01

system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment. PMID:21876532

Design of a cyclic pressure bioreactor for the ex vivo study of aortic heart valves.

PubMed

Schipke, Kimberly J; To, S D Filip; Warnock, James N

2011-08-23

air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Use of the proGAV shunt valve in normal-pressure hydrocephalus.

PubMed

Toma, Ahmed K; Tarnaris, Andrew; Kitchen, Neil D; Watkins, Laurence D

2011-06-01

Overdrainage is a common complication associated with shunt insertion in normal-pressure hydrocephalus (NPH) patients. Using adjustable valves with antigravity devices has been shown to reduce its incidence. The optimal starting setting of an adjustable shunt valve in NPH is debatable. To audit our single-center practice of setting adjustable valves. We performed a retrospective review of clinical records of all NPH patients treated in our unit between 2006 and 2009 by the insertion of shunts with a proGAV valve, recording demographic and clinical data, shunt complications, and revision rates. Radiological reports of postoperative follow-up computed tomography scans of the brain were reviewed for detected subdural hematomas. A proGAV adjustable valve was inserted in 50 probable NPH patients between July 2006 and November 2009. Mean ± SD age was 76 ± 7 years. Mean follow-up was 15 months. The initial shunt setting was 6 ± 3 cm H2O, and the final setting was 4.9 ± 1.9 cm H2O. Nineteen patients required 24 readjustment procedures (readjustment rate, 38%; readjustment number, 0.48 times per patient). One patient (2%) developed delayed bilateral subdural hematoma after readjustment of his shunt valve setting as an outpatient. Starting with a low opening pressure setting on a proGAV adjustable shunt valve does not increase the chances of overdrainage complications and reduces the need for repeated readjustments.

46 CFR 154.806 - Capacity of pressure relief valves.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Capacity of pressure relief valves. 154.806 Section 154... Equipment Cargo Vent Systems § 154.806 Capacity of pressure relief valves. Pressure relief valves for each cargo tank must have a combined relief capacity, including the effects of back pressure from vent piping...

40 CFR 63.167 - Standards: Open-ended valves or lines.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines... PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES...: Open-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap, blind...

46 CFR 105.10-20 - Pressure vacuum relief valve.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Pressure vacuum relief valve. (a) The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of pressure or vacuum in enclosed... 46 Shipping 4 2011-10-01 2011-10-01 false Pressure vacuum relief valve. 105.10-20 Section 105.10...

46 CFR 105.10-20 - Pressure vacuum relief valve.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Pressure vacuum relief valve. (a) The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of pressure or vacuum in enclosed... 46 Shipping 4 2010-10-01 2010-10-01 false Pressure vacuum relief valve. 105.10-20 Section 105.10...

46 CFR 105.10-20 - Pressure vacuum relief valve.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Pressure vacuum relief valve. (a) The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of pressure or vacuum in enclosed... 46 Shipping 4 2014-10-01 2014-10-01 false Pressure vacuum relief valve. 105.10-20 Section 105.10...

46 CFR 105.10-20 - Pressure vacuum relief valve.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Pressure vacuum relief valve. (a) The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of pressure or vacuum in enclosed... 46 Shipping 4 2012-10-01 2012-10-01 false Pressure vacuum relief valve. 105.10-20 Section 105.10...

46 CFR 105.10-20 - Pressure vacuum relief valve.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Pressure vacuum relief valve. (a) The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of pressure or vacuum in enclosed... 46 Shipping 4 2013-10-01 2013-10-01 false Pressure vacuum relief valve. 105.10-20 Section 105.10...

46 CFR 64.59 - Spring loaded pressure relief valve.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Spring loaded pressure relief valve. 64.59 Section 64.59... AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.59 Spring loaded pressure relief valve. A spring loaded pressure relief valve must— (a) Be set at a nominal...

46 CFR 64.59 - Spring loaded pressure relief valve.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Spring loaded pressure relief valve. 64.59 Section 64.59... AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.59 Spring loaded pressure relief valve. A spring loaded pressure relief valve must— (a) Be set at a nominal...

46 CFR 64.59 - Spring loaded pressure relief valve.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Spring loaded pressure relief valve. 64.59 Section 64.59... AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.59 Spring loaded pressure relief valve. A spring loaded pressure relief valve must— (a) Be set at a nominal...

46 CFR 64.59 - Spring loaded pressure relief valve.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Spring loaded pressure relief valve. 64.59 Section 64.59... AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.59 Spring loaded pressure relief valve. A spring loaded pressure relief valve must— (a) Be set at a nominal...

46 CFR 64.59 - Spring loaded pressure relief valve.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Spring loaded pressure relief valve. 64.59 Section 64.59... AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.59 Spring loaded pressure relief valve. A spring loaded pressure relief valve must— (a) Be set at a nominal...

Programmable valve shunts: are they really better?

PubMed

Kataria, Rashim; Kumar, Vimal; Mehta, Veer Singh

2012-01-01

Programmable valve shunts allows selection of opening pressure of shunt valve. In the presented article, a unique complication pertaining to programmable shunts has been discussed. A 5-year-old boy who had tectal plate low grade glioma with obstructive hydrocephalus was managed with Codman programmable ventriculoperitoneal shunt. There was a spontaneous change in the opening pressure of the shunt valve leading to shunt malfunction. Routinely used household appliances produce a magnetic field strong enough to cause change in the setting of shunt valve pressure and may lead to valve malfunction. Other causes of programmable valve malfunction also discussed.

40 CFR 265.1056 - Standards: Open-ended valves or lines.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., STORAGE, AND DISPOSAL FACILITIES Air Emission Standards for Equipment Leaks § 265.1056 Standards: Open-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap, blind flange... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines...

40 CFR 63.1014 - Open-ended valves or lines standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Open-ended valves or lines standards... (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 1 § 63.1014 Open-ended valves or... requirements. (1) Each open-ended valve or line shall be equipped with a cap, blind flange, plug, or a second...

40 CFR 61.242-6 - Standards: Open-ended valves or lines.

Code of Federal Regulations, 2010 CFR

2010-07-01

... for Equipment Leaks (Fugitive Emission Sources) § 61.242-6 Standards: Open-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap, blind flange, plug, or a second valve... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines...

Adjustable valves in normal-pressure hydrocephalus: a retrospective study of 218 patients.

PubMed

Zemack, Göran; Romner, Bertil

2002-12-01

We sought to assess the value of adjusting shunt valve opening pressure, complications, and outcomes with the use of an adjustable shunt valve in the treatment of patients with normal-pressure hydrocephalus (NPH). In a single-center retrospective study, 231 adjustable valves (range, 30-200 mm H(2)O) were the first shunt implantations in 147 patients with idiopathic NPH (INPH) and 71 patients with secondary NPH (SNPH). The effect of adjustment on gait disturbance, cognitive impairment, urinary incontinence and other symptoms were evaluated, and an improvement index was created. In the INPH group, 138 adjustments were performed in 49.0% of the patients (average, 0.94 adjustments/patient). For the SNPH group, 49 adjustments were performed in 32.4% of the patients (average, 0.69 adjustments/patient). The reasons for adjustment were overdrainage in 48 patients (25.7%), underdrainage in 98 patients (52.4%), subdural hematoma in 37 patients (19.8%), and other reasons in 2 patients (2.1%). Clinical status improved after 56 (49.1%) of all 114 adjustments, whereas 23 (42.6%) of 54 minor (< or =20 mm H2O) and 33 (66.0%) of 50 larger adjustments improved the patient's clinical status. The correlation of the improvement index with the size of the individual adjustments was not significant. Complications occurred in 43 (19.7%) of 218 patients, valve malfunction occurred in 3 patients (1.3%), infection occurred in 14 patients (6.4%), and nontraumatic subdural effusion occurred in 15 patients (6.9%; 8 were treated by adjustment alone). The 5-year shunt survival rate was 80.2%. Outcomes were excellent or good in 71 (78.9%) of 90 patients with INPH and in 30 (69.8%) of 43 patients with SNPH. Noninvasive, particularly consecutive, minor or single larger adjustments to the valve opening pressure can further improve outcome in patients with NPH who undergo shunting.

Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate

PubMed Central

Rogers, Chad I.; Oxborrow, Joseph B.; Anderson, Ryan R.; Tsai, Long-Fang; Nordin, Gregory P.; Woolley, Adam T.

2013-01-01

Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ~100 ms valve opening time and a ~20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ~50 kPa higher than the control pressure holding the valve closed. However, after ~1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations. Such valves constructed from non-adsorptive poly-PEGDA could also find use as pumps, for application in small volume assays interfaced with biosensors or impedance detection, for example. PMID:24357897

Combined pressure regulator and shutoff valve

NASA Technical Reports Server (NTRS)

Koch, E. F. (Inventor)

1974-01-01

A remotely operable pressure regulator and shutoff valve particularly suited for achieving high resolution and flow control, and positive shutoff is described. The valve is characterized by a spring-loaded ball coaxially aligned with a fluid port to be sealed, a spring-loaded pintle extended through the port into engagement with the ball, for controlling the position, a spring-loaded diaphragm for controlling the position of the pintle, and an axially displaceable spring supported by a movable stop which, in turn, is repositioned by a selectively operable stepper motor. Thus, the pressure-response characteristics for the valve can be varied through a selective repositioning of the stop.

High-temperature, high-pressure oxygen metering valve

NASA Technical Reports Server (NTRS)

Christianson, Rollin C. (Inventor); Lycou, Peter P. (Inventor); Daniel, James A. (Inventor)

1993-01-01

A control valve includes a body defining a central cavity arranged between a fluid inlet and outwardly-diverging first and second fluid outlets respectively disposed in a common transverse plane. A valve member is arranged in the cavity for rotation between first and second operating positions where a transverse fluid passage through the valve member alternatively communicates the fluid inlet with one or the other of the fluid outlets. To minimize fluid turbulence when the valve member is rotated to an alternate operating position, the fluid passage has a convergent entrance for maintaining the passage in permanent communication with the fluid inlet as well as an oblong exit opening with spaced side walls for enabling the exit opening to temporarily span the first and second fluid outlets as the valve member is turned between its respective operating positions.

40 CFR 60.482-6 - Standards: Open-ended valves or lines.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines... PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for... Standards: Open-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap...

Optimized surgical treatment for normal pressure hydrocephalus: comparison between gravitational and differential pressure valves.

PubMed

Suchorska, B; Kunz, M; Schniepp, R; Jahn, K; Goetz, C; Tonn, J C; Peraud, A

2015-04-01

In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is the method of choice to improve cardinal symptoms such as gait disturbance, urge incontinence and/or dementia. With reduced compliance, the brain of the elderly is prone for overdrainage complications. This was especially true with the use of differential pressure valve implantation. The present study compares clinical outcome and complication rates after VP shunt insertion with differential pressure valves in the early years and gravitational valves since 2005. The authors reviewed patients treated at our institution for NPH since 1995. Differential pressure valves were solely used in the initial years, while the treatment regimen changed to gravitational valves in 2005. Clinical improvement/surgical success rates as well as complications were compared between the two groups. Eighty-nine patients were enrolled for the present study. Mean age at the time of surgery was 73.5 ± 6.3 years. Male patients predominated with 73, compared with 16 female patients. Median follow-up time was 28 ± 26 months. Date of last follow-up was 1st October 2013. Forty-nine patients received a gravitational valve, while 40 were treated with differential pressure valves. In the gravitational group a significant improvement was observed after shunt insertion for gait disorder, cognitive impairment and urge incontinence (p < 0.0001, resp. p = 0.004), while a significant change in the differential pressure group was only seen for gait disorder (p = 0.03) but not for cognition or urinary incontinency (p > 0.05). The risk of hygroma as a sign of shunt overdrainage requiring surgical intervention was significantly higher in the differential pressure group (5 versus 0 in the gravitational group). Patients with NPH treated with gravitational valves in the present cohort showed a more profound improvement in their initial symptoms, including gait disorder, cognitive impairment

Best-estimate coupled RELAP/CONTAIN analysis of inadvertent BWR ADS valve opening transient

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

Feltus, M.A.; Muftuoglu, A.K.

1993-01-01

Noncondensible gases may become dissolved in boiling water reactor (BWR) water-level instrumentation during normal operations. Any dissolved noncondensible gases inside these water columns may come out of solution during rapid depressurization events and displace water from the reference leg piping, resulting in a false high level. Significant errors in water-level indication are not expected to occur until the reactor pressure vessel (RPV) pressure has dropped below [approximately]450 psig. These water level errors may cause a delay or failure in emergency core cooling system (ECCS) actuation. The RPV water level is monitored using the pressure of a water column having amore » varying height (reactor water level) that is compared to the pressure of a water column maintained at a constant height (reference level). The reference legs have small-diameter pipes with varying lengths that provide a constant head of water and are located outside the drywell. The amount of noncondensible gases dissolved in each reference leg is very dependent on the amount of leakage from the reference leg and its geometry and interaction of the reactor coolant system with the containment, i.e., torus or suppression pool, and reactor building. If a rapid depressurization causes an erroneously high water level, preventing automatic ECCS actuation, it becomes important to determine if there would be other adequate indications for operator response. In the postulated inadvertent opening of all seven automatic depressurization system (ADS) valves, the ECCS signal on high drywell pressure would be circumvented because the ADS valves discharge directly into the suppression pool. A best-estimate analysis of such an inadvertent opening of all ADS valves would have to consider the thermal-hydraulic coupling between the pool, drywell, reactor building, and RPV.« less

Low energy high pressure miniature screw valve

DOEpatents

Fischer, Gary J [Sandia Park, NM; Spletzer, Barry L [Albuquerque, NM

2006-12-12

A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

Dual-Latching, Solenoid-Actuated Tube Valve

NASA Technical Reports Server (NTRS)

Brudnicki, Myron J.

1993-01-01

Tube-type shutoff valve electrically positioned to open or closed state by concentric solenoid. Solenoid dual latching: it holds position until changed electrically or manually. In tube valve, central tube slides axially, closing off flow when held against seat and allowing flow when backed away from seat. Simple to balance pressure on seal between seat and sharp edge of tube. With pressure-balanced seal, only small force needed to hold valve in position, regardless of pressure acting on valve.

40 CFR 63.1033 - Open-ended valves or lines standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Open-ended valves or lines standards... (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 2 Standards § 63.1033 Open-ended... requirements. (1) Each open-ended valve or line shall be equipped with a cap, blind flange, plug, or a second...

Functional Changes of Diaphragm Type Shunt Valves Induced by Pressure Pulsation

NASA Astrophysics Data System (ADS)

Lee, Chong-Sun; Suh, Chang-Min; Ra, Young-Shin

Shunt valves used to treat patients with hydrocephalus were tested to investigate influence of pressure pulsation on their flow control characteristics. Our focus was on flow dynamic and functional changes of the small and thin diaphragms in the valves that serve as the main flow control mechanism and are made from silicone elastomer. Firstly, pressure-flow control curves were compared under pulsed and steady flow (without pulsation) conditions. Secondly, functional changes of the valves were tested after a long-term continuous pulsation with a peristaltic pump. Thirdly, flushing procedures selectively conducted by neurosurgeons were simulated with a fingertip pressed on the dome of the valves. As 20cc/hr of flow rate was adjusted at a constant pressure, application of 40mmH2O of pressure pulse increased flow rate through shunt valves more than 60%. As a 90cm length silicone catheter was connected to the valve outlet, increase in the flow rate was substantially reduced to 17.5%. Pressure-flow control characteristics of some valves showed significant changes after twenty-eight days of pressure pulsation at 1.0 Hz under 50.0cc/hr of flow rate. Flushing simulation resulted in temporary decrease in the pressure level. It took three hours to fully recover the normal pressure-flow control characteristics after the flushing. Our results suggest that shunt valves with a thin elastic diaphragm as the main flow control mechanism are sensitive to intracranial pressure pulsation or pressure spikes enough to change their pressure-flow control characteristics.

Electrically Controlled Valve With Small Motor

NASA Technical Reports Server (NTRS)

Reinicke, Robert H.; Mohtar, Rafic; Nelson, Richard O.

1992-01-01

Design of electrically controlled valve exploits force-multiplying principle to overcome large back-pressure force resisting initial opening. Design makes possible to open valve by use of relatively small motor adequate for rest of valve motion, but otherwise not large enough to open valve. In simple linear lifting, small horizontal forces applied to pair of taut cables to lift large weight through short distance. In rotary lifting, similar effect achieved by rotating, about an axis, disk to which initially axial cables attached.

The challenge of valve-in-valve procedures in degenerated Mitroflow bioprostheses and the advantage of using the JenaValve transcatheter heart valve.

PubMed

Conradi, Lenard; Kloth, Benjamin; Seiffert, Moritz; Schirmer, Johannes; Koschyk, Dietmar; Blankenberg, Stefan; Reichenspurner, Hermann; Diemert, Patrick; Treede, Hendrik

2014-12-01

Recently, the feasibility of valve-in-valve procedures using current first-generation transcatheter heart valves (THV) in cases of structural valve degeneration has been reported as an alternative to conventional open repeat valve replacement. By design, certain biological valve xenografts carry a high risk of coronary ostia occlusion due to lateral displacement of leaflets after valve-in-valve procedures. In the present report we aimed to prove feasibility and safety of transapical valve-in-valve implantation of the JenaValve THV in two cases of degenerated Mitroflow bioprostheses. We herein report two cases of successful transapical valve-in-valve procedures using a JenaValve THV implanted in Sorin Mitroflow bioprostheses for structural valve degeneration. Both patients were alive and in good clinical condition at 30 days from the procedure. However, increased transvalvular gradients were noted in both cases. Transcatheter valve-in-valve implantation of a JenaValve THV is a valid alternative for patients with degenerated Mitroflow bioprostheses of sufficient size and in the presence of short distances to the coronary ostia who are too ill for conventional repeat open heart surgery. Increased pressure gradients have to be expected and weighed against the disadvantages of other treatment options when planning such a procedure.

A randomised trial of high and low pressure level settings on an adjustable ventriculoperitoneal shunt valve for idiopathic normal pressure hydrocephalus: results of the Dutch evaluation programme Strata shunt (DEPSS) trial.

PubMed

Delwel, Ernst J; de Jong, Dirk A; Dammers, Ruben; Kurt, Erkan; van den Brink, Wimar; Dirven, Clemens M F

2013-07-01

In treating idiopathic normal pressure hydrocephalus (INPH) with a shunt there is always a risk of underdrainage or overdrainage. The hypothesis is tested whether patients treated using an adjustable valve preset at the highest opening pressure leads to comparable good clinical results with less subdural effusions than in a control group with an opening pressure preset at a low pressure level. A multicentre prospective randomised trial was performed on a total of 58 patients suspected of INPH. Thirty patients were assigned to (control) group 1 and received a Strata shunt (Medtronic, Goleta, USA) with the valve preset at a performance level (PL) of 1.0, while 28 patients were assigned to group 2 and received a Strata shunt with the valve preset at PL 2.5. In this group the PL was allowed to be lowered until improvement or radiological signs of overdrainage were met. Significantly more subdural effusions were observed in the improved patients of group 1. There was no statistically significant difference in improvement between both groups overall. On the basis of this multicentre prospective randomised trial it is to be recommended to treat patients with INPH with a shunt with an adjustable valve, preset at the highest opening pressure and lowered until clinical improvement or radiological signs of overdrainage occur although slower improvement and more shunt adjustments might be the consequence.

The aortic valve microstructure: effects of transvalvular pressure.

PubMed

Sacks, M S; Smith, D B; Hiester, E D

1998-07-01

We undertook this study to establish a more quantitative understanding of the microstructural response of the aortic valve cusp to pressure loading. Fresh porcine aortic valves were fixed at transvalvular pressures ranging from 0 mmHg to 90 mmHg, and small-angle light scattering (SALS) was used to quantify the gross fiber structure of the valve cusps. At all pressures the fiber-preferred directions coursed along the circumferential direction. Increasing transvalvular pressure induced the greatest changes in fiber alignment between 0 and 1 mmHg, with no detectable change past 4 mmHg. When the fibrosa and ventricularis layers of the cusps were re-scanned separately, the fibrosa layer revealed a higher degree of orientation while the ventricularis was more randomly oriented. The degree of fiber orientation for both layers became more similar once the transvalvular pressure exceeded 4 mmHg, and the layers were almost indistinguishable by 60 mmHg. It is possible that, in addition to retracting the aortic cusp during systole, the ventricularis mechanically may contribute to the diastolic cuspal stiffness at high transvalvular pressures, which may help to prevent over distention of the cusp. Our results suggest a complex, highly heterogeneous structural response to transvalvular pressure on a fiber level that will have to be duplicated in future bioprosthetic heart valve designs.

How Heart Valves Evolve to Adapt to an Extreme-Pressure System: Morphologic and Biomechanical Properties of Giraffe Heart Valves.

PubMed

Amstrup Funder, Jonas; Christian Danielsen, Carl; Baandrup, Ulrik; Martin Bibby, Bo; Carl Andelius, Ted; Toft Brøndum, Emil; Wang, Tobias; Michael Hasenkam, J

2017-01-01

Heart valves which exist naturally in an extreme-pressure system must have evolved in a way to resist the stresses of high pressure. Giraffes are interesting as they naturally have a blood pressure twice that of humans. Thus, knowledge regarding giraffe heart valves may aid in developing techniques to design improved pressure-resistant biological heart valves. Heart valves from 12 giraffes and 10 calves were explanted and subjected to either biomechanical or morphological examinations. Strips from the heart valves were subjected to cyclic loading tests, followed by failure tests. Thickness measurements and analyses of elastin and collagen content were also made. Valve specimens were stained with hematoxylin and eosin, elastic van Gieson stain, Masson's trichrome and Fraser-Lendrum stain, as well as immunohistochemical reactions for morphological examinations. The aortic valve was shown to be 70% (95% CI 42-103%) stronger in the giraffe than in its bovine counterpart (p <0.001). No significant difference was found between mitral or pulmonary valves. After normalization for collagen, no significant differences were found in strength between species. The giraffe aortic valve was found to be significantly stiffer than the bovine aortic valve (p <0.001), with no significant difference between mitral and pulmonary valves. On a dry weight basis, the aortic (10.9%), pulmonary (4.3%), and mitral valves (9.6%) of giraffes contained significantly more collagen than those of calves. The elastin contents of the pulmonary valves (2.5%) and aortic valves (1.5%) were also higher in giraffes. The greater strength of the giraffe aortic valve is most likely due to a compact collagen construction. Both, collagen and elastin contents were higher in giraffes than in calves, which would make giraffe valves more resistant to the high-pressure forces. However, collagen also stiffens and thickens the valves. The mitral leaflets showed similar (but mostly insignificant) trends in strength

40 CFR 63.1014 - Open-ended valves or lines standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Open-ended valves or lines standards... PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 1 § 63.1014 Open-ended valves or...

Solenoid hammer valve developed for quick-opening requirements

NASA Technical Reports Server (NTRS)

Wrench, E. H.

1967-01-01

Quick-opening lightweight solenoid hammer valve requires a low amount of electrical energy to open, and closes by the restoring action of the mechanical springs. This design should be applicable to many quick-opening requirements in fluid systems.

A simple fast pulse gas valve using a dynamic pressure differential as the primary closing mechanism

NASA Astrophysics Data System (ADS)

Thomas, J. C.; Hwang, D. Q.; Horton, R. D.; Rogers, J. H.; Raman, R.

1993-06-01

In this article we describe a simple fast pulse gas valve developed for use in a plasma discharge experiment. The valve delivers 1017-1019 molecules per pulse varied by changing the voltage on the electromagnetic driver power supply. Valve pulse widths are observed to be less than 300 μs full width at half maximum with a rise time of less than 100 μs resulting in a maximum gas flow rate of ˜1022 molecules per second. An optical transmission technique was used to determine the mechanical opening and closing characteristics of the valve piston. A fast ionization gauge (FIG) was used for diagnosis of the temporal character of the gas pulse while the total gas throughput was determined by measuring the change in pressure per pulse in a small test chamber with a convectron tube gauge. Calibration of the FIG was accomplished by comparing the net change in pressure in a large chamber as measured by the FIG to the net change in pressure in a small test chamber as measured by the convectron tube gauge.

Navier-Stokes flow field analysis of compressible flow in a high pressure safety relief valve

NASA Technical Reports Server (NTRS)

Vu, Bruce; Wang, Ten-See; Shih, Ming-Hsin; Soni, Bharat

1993-01-01

The objective of this study is to investigate the complex three-dimensional flowfield of an oxygen safety pressure relieve valve during an incident, with a computational fluid dynamic (CFD) analysis. Specifically, the analysis will provide a flow pattern that would lead to the expansion of the eventual erosion pattern of the hardware, so as to combine it with other findings to piece together a most likely scenario for the investigation. The CFD model is a pressure based solver. An adaptive upwind difference scheme is employed for the spatial discretization, and a predictor, multiple corrector method is used for the velocity-pressure coupling. The computational result indicated vortices formation near the opening of the valve which matched the erosion pattern of the damaged hardware.

Preliminary engineering study: Quick opening valve MSFC high Reynolds number wind tunnel

NASA Technical Reports Server (NTRS)

1983-01-01

FluiDyne Engineering Corporation has conducted a preliminary engineering study of a quick-opening valve for the MSFC High Reynolds Number Wind Tunnel under NASA Contract NAS8-35056. The subject valve is intended to replace the Mylar diaphragm system as the flow initiation device for the tunnel. Only valves capable of opening within 0.05 sec. and providing a minimum of 11.4 square feet of flow area were considered. Also, the study focused on valves which combined the quick-opening and tight shutoff features in a single unit. A ring sleeve valve concept was chosen for refinement and pricing. Sealing for tight shutoff, ring sleeve closure release and sleeve actuation were considered. The resulting cost estimate includes the valve and requisite modifications to the facility to accommodate the valve as well as the associated design and development work.

49 CFR 179.400-21 - Test of pressure relief valves.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 3 2013-10-01 2013-10-01 false Test of pressure relief valves. 179.400-21 Section... CARS Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-21 Test of pressure relief valves. Each valve must be tested with air or gas for...

49 CFR 179.400-21 - Test of pressure relief valves.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Test of pressure relief valves. 179.400-21 Section... FOR TANK CARS Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-21 Test of pressure relief valves. Each valve must be tested with air or gas...

Double-reed exhaust valve engine

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

Bennett, Charles L.

An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a double reed outlet valve for controlling the flow of low-pressure working fluid out of the engine. The double reed provides a stronger force resisting closure of the outlet valve than the force tending to open the outlet valve. The double reed valve enables engine operation at relatively higher torque and lower efficiency at low speed, with lower torque, but higher efficiency at high speed.

Development Specification for RV-346/348 Positive Pressure Relief Valves (PPRV)

NASA Technical Reports Server (NTRS)

Ralston, Russell L.

2017-01-01

This specification establishes the requirements for design, performance, safety, testing, and manufacture of the RV-346 and RV-348, Positive Pressure Relief Valve (PPRV) as part of the Advanced Extravehicular Mobility Unit (EMU)(AEMU) Portable Life Support System (PLSS). The RV-346 serves as the Positive Pressure Relief Valve (PPRV), and the RV-348 serves as the Secondary Positive Pressure Relief Valve (SPPRV).

Sliding pressure control valve for pneumatic hammer drill

DOEpatents

Polsky, Yarom [Albuquerque, NM

2011-08-30

A pneumatic device control apparatus and method comprising a ported valve slidably fitted over a feed tube of the pneumatic device, and using a compliant biasing device to constrain motion of the valve to provide asymmetric timing for extended pressurization of a power chamber and reduced pressurization of a return chamber of the pneumatic device. The pneumatic device can be a pneumatic hammer drill.

Shock-operated valve would automatically protect fluid systems

NASA Technical Reports Server (NTRS)

Branum, L. W.; Wells, G. H.

1966-01-01

Glandless valve shuts down high-pressure fluid systems when severe shock from an explosion or earthquake occurs. The valve uses a pendulum to support the valve closure plug in the open position. When jarred, the valve body is moved relative to the pendulum and the plug support is displaced, allowing the plug to seat and be held by spring pressure.

The value of programmable shunt valves for the management of subdural collections in patients with hydrocephalus.

PubMed

Pachatouridis, Dimitrios; Alexiou, George A; Mihos, Evaggelos; Fotakopoulos, George; Voulgaris, Spyridon

2013-01-01

The aim of the present study was to assess the value of electromagnetic programmable shunt valves for the treatment of subdural collections. Adult patients with hydrocephalus of various causes that were treated with programmable shunt valves during the last ten years were retrospectively studied. In 127 patients, 139 electromagnetic programmable shunt valves were implanted. A nontraumatic subdural fluid collection was detected in 12 patients. The treatment of these patients consisted of reprogramming of the valve's opening pressure. In 5 patients small subdural hematomas were detected; 4 of these patients were treated by raising the opening pressure alone and one patient required surgical drainage and change of the pressure setting. Traumatic chronic subdural hematomas were detected in 6 patients. These patients were treated by surgical drainage and readjustment of the valve's opening pressure. The ability to treat a shunt-related complication, such as a subdural fluid collection, by reprogramming the valve's opening pressure to a higher setting is an advantage over nonprogrammable valves, and it enables the opening pressure to be slowly lowered once the fluid collection is reabsorbed. Based on our results, we believe that programmable shunt valves should be preferred.

The Value of Programmable Shunt Valves for the Management of Subdural Collections in Patients with Hydrocephalus

PubMed Central

Alexiou, George A.; Mihos, Evaggelos; Fotakopoulos, George; Voulgaris, Spyridon

2013-01-01

Background. The aim of the present study was to assess the value of electromagnetic programmable shunt valves for the treatment of subdural collections. Methods. Adult patients with hydrocephalus of various causes that were treated with programmable shunt valves during the last ten years were retrospectively studied. In 127 patients, 139 electromagnetic programmable shunt valves were implanted. Results. A nontraumatic subdural fluid collection was detected in 12 patients. The treatment of these patients consisted of reprogramming of the valve's opening pressure. In 5 patients small subdural hematomas were detected; 4 of these patients were treated by raising the opening pressure alone and one patient required surgical drainage and change of the pressure setting. Traumatic chronic subdural hematomas were detected in 6 patients. These patients were treated by surgical drainage and readjustment of the valve's opening pressure. Conclusion. The ability to treat a shunt-related complication, such as a subdural fluid collection, by reprogramming the valve's opening pressure to a higher setting is an advantage over nonprogrammable valves, and it enables the opening pressure to be slowly lowered once the fluid collection is reabsorbed. Based on our results, we believe that programmable shunt valves should be preferred. PMID:24453855

Depressurization valve

DOEpatents

Skoda, G.I.

1989-03-28

A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring-preferably of the Belleville variety-acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion.

Valve assembly for use with high temperature and high pressure fluids

DOEpatents

De Feo, Angelo

1982-01-01

The valve assembly for use with high temperature and high pressure fluids has inner and outer spaced shells and a valve actuator support of inner and outer spaced members which are connected at their end portions to the inner and outer shells, respectively, to extend substantially normal to the longitudinal axis of the inner shell. A layer of resilient heat insulating material covers the outer surfaces of the inner shell and the inner actuator support member and is of a thickness to only occupy part of the spaces between the inner and outer shells and inner and outer actuator support members. The remaining portion of the space between the inner and outer shells and the space between the inner and outer members is substantially filled with a body of castable, rigid refractory material. A movable valve member is disposed in the inner shell. A valve actuator assembly is supported in the valve actuator support to extend into the inner shell for connection with the movable valve member for movement of the movable valve member to positions from a fully open to a fully closed position to control flow of fluid through the inner shell. An anchor mneans is disposed adjacent opposite sides of the axis of the valve actuator support and attached to the inner shell so that relative radial movement between the inner and outer shell is permitted by the layer of resilient heat insulating material and relative longitudinal movement of the inner shell to the outer shell is permitted in opposite directions from the anchor means to thereby maintain the functional integrity of the movable valve member by providing an area of the inner shell surrounding the movable valve member longitdinally stationary, but at the same time allowing radial movement.

Pressure tracking control of vehicle ABS using piezo valve modulator

NASA Astrophysics Data System (ADS)

Jeon, Juncheol; Choi, Seung-Bok

2011-03-01

This paper presents a wheel slip control for the ABS(anti-lock brake system) of a passenger vehicle using a controllable piezo valve modulator. The ABS is designed to optimize for braking effectiveness and good steerability. As a first step, the principal design parameters of the piezo valve and pressure modulator are appropriately determined by considering the braking pressure variation during the ABS operation. The proposed piezo valve consists of a flapper, pneumatic circuit and a piezostack actuator. In order to get wide control range of the pressure, the pressure modulator is desired. The modulator consists of a dual-type cylinder filled with different substances (fluid and gas) and a piston rod moving vertical axis to transmit the force. Subsequently, a quarter car wheel slip model is formulated and integrated with the governing equation of the piezo valve modulator. A sliding mode controller to achieve the desired slip rate is then designed and implemented. Braking control performances such as brake pressure and slip rate are evaluated via computer simulations.

Analysis of pressure losses in the diffuser of a control valve

NASA Astrophysics Data System (ADS)

Turecký, Petr; Mrózek, Lukáš; Tajč, Ladislav; Kolovratník, Michal

The pressure loss in the diffuser of a control valve is evaluated by using CFD computations. Pressure ratios and lifts of a cone for the recommended flow characteristics of an experimental turbine are considered. The pressure loss in a valve is compared with the pressure loss in a nozzle, i.e. the embodiment of the valve without a cone. Computations are carried out for the same mass flow. Velocity profiles are evaluated in both versions of computations. Comparison of computed pressure losses, with the loss evaluated by using relations for diffusers with the ideal velocity conditions in the input cross-section, is carried out.

Development of a micro-mechanical valve in a novel glaucoma implant.

PubMed

Siewert, Stefan; Schultze, Christine; Schmidt, Wolfram; Hinze, Ulf; Chichkov, Boris; Wree, Andreas; Sternberg, Katrin; Allemann, Reto; Guthoff, Rudolf; Schmitz, Klaus-Peter

2012-10-01

This paper describes methods for design, manufacturing and characterization of a micro-mechanical valve for a novel glaucoma implant. The implant is designed to drain aqueous humour from the anterior chamber of the eye into the suprachoroidal space in case of an elevated intraocular pressure (IOP). In contrast to any existing glaucoma drainage device (GDD), the valve mechanism is located in the anterior chamber and there, surrounded by aqueous humour, immune to fibrosis induced failure. For the prevention of hypotony the micro-mechanical valve is designed to open if the physiological pressure difference between the anterior chamber and the suprachoroidal space in the range of 0.8 mmHg to 3.7 mmHg is exceeded. In particular the work includes: (i) manufacturing and morphological characterization of polymer tubing, (ii) mechanical material testing as basis for (iii) the design of micro-mechanical valves using finite element analysis (FEA), (iv) manufacturing of microstent prototypes including micro-mechanical valves by femtosecond laser micromachining and (v) the experimental fluid-mechanical characterization of the manufactured microstent prototypes with regard to valve opening pressure. The considered materials polyurethane (PUR) and silicone (SIL) exhibit low elastic modulus and high extensibility. The unique valve design enables a low opening pressure of micro-mechanical valves. An ideal valve design for PUR and SIL with an experimentally determined opening pressure of 2 mmHg and 3.7 mmHg is identified. The presented valve approach is suitable for the inhibition of hypotony as a major limitation of today's GDD and will potentially improve the minimally invasive treatment of glaucoma.

40 CFR 264.1056 - Standards: Open-ended valves or lines.

Code of Federal Regulations, 2010 CFR

2010-07-01

... hazardous waste stream end is closed before the second valve is closed. (c) When a double block and bleed system is being used, the bleed valve or line may remain open during operations that require venting the...

Impact characteristics for high-pressure large-flow water-based emulsion pilot operated check valve reverse opening

NASA Astrophysics Data System (ADS)

Liu, Lei; Huang, Chuanhui; Yu, Ping; Zhang, Lei

2017-10-01

To improve the dynamic characteristics and cavitation characteristics of large-flow pilot operated check valve, consider the pilot poppet as the research object, analyses working principle and design three different kinds of pilot poppets. The vibration characteristics and impact characteristics are analyzed. The simulation model is established through flow field simulation software. The cavitation characteristics of large-flow pilot operated check valve are studied and discussed. On this basis, high-pressure large-flow impact experimental system is used for impact experiment, and the cavitation index is discussed. Then optimal structure is obtained. Simulation results indicate that the increase of pilot poppet half cone angle can effectively reduce the cavitation area, reducing the generation of cavitation. Experimental results show that the pressure impact is not decreasing with increasing of pilot poppet half cone angle in process of unloading, but the unloading capacity, response speed and pilot poppet half cone angle are positively correlated. The impact characteristics of 60° pilot poppet, and its cavitation index is lesser, which indicates 60° pilot poppet is the optimal structure, with the theory results are basically identical.

Bioprosthetic Valve Fracture to Facilitate Transcatheter Valve-in-Valve Implantation.

PubMed

Allen, Keith B; Chhatriwalla, Adnan K; Cohen, David J; Saxon, John T; Aggarwal, Sanjeev; Hart, Anthony; Baron, Suzanne; Davis, J Russell; Pak, Alex F; Dvir, Danny; Borkon, A Michael

2017-11-01

Valve-in-valve transcatheter aortic valve replacement is less effective in small surgical bioprostheses. We evaluated the feasibility of bioprosthetic valve fracture with a high-pressure balloon to facilitate valve-in-valve transcatheter aortic valve replacement. In vitro bench testing on aortic tissue valves was performed on 19-mm and 21-mm Mitroflow (Sorin, Milan, Italy), Magna and Magna Ease (Edwards Lifesciences, Irvine, CA), Trifecta and Biocor Epic (St. Jude Medical, Minneapolis, MN), and Hancock II and Mosaic (Medtronic, Minneapolis, MN). High-pressure balloons Tru Dilation, Atlas Gold, and Dorado (C.R. Bard, Murray Hill, NJ) were used to determine which valves could be fractured and at what pressure fracture occurred. Mitroflow, Magna, Magna Ease, Mosaic, and Biocor Epic surgical valves were successfully fractured using high-pressures balloon 1 mm larger than the labeled valve size whereas Trifecta and Hancock II surgical valves could not be fractured. Only the internal valve frame was fractured, and the sewing cuff was never disrupted. Manufacturer's rated burst pressures for balloons were exceeded, with fracture pressures ranging from 8 to 24 atmospheres depending on the surgical valve. Testing further demonstrated that fracture facilitated the expansion of previously constrained, underexpanded transcatheter valves (both balloon and self-expanding) to the manufacturer's recommended size. Bench testing demonstrates that the frame of most, but not all, bioprosthetic surgical aortic valves can be fractured using high-pressure balloons. The safety of bioprosthetic valve fracture to optimize valve-in-valve transcatheter aortic valve replacement in small surgical valves requires further clinical investigation. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Depressurization valve

DOEpatents

Skoda, George I.

1989-01-01

A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring--preferably of the Belleville variety--acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion. The latch plate in surrounding the stem is limited in its outward movement by a boss attached to the stem at the end of

49 CFR 179.220-24 - Tests of pressure relief valves.

Code of Federal Regulations, 2012 CFR

2012-10-01

... HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-24 Tests of pressure relief valves. Each safety relief valve must be tested by air or gas for compliance with § 179.15...

49 CFR 179.220-24 - Tests of pressure relief valves.

Code of Federal Regulations, 2011 CFR

2011-10-01

... HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-24 Tests of pressure relief valves. Each safety relief valve must be tested by air or gas for compliance with § 179.15...

VACUUM TRAP AND VALVE COMBINATION

DOEpatents

Milleron, N.; Levenson, L.

1963-02-19

This patent relates to a vacuum trap and valve combination suitable for use in large ultra-high vacuum systems. The vacuum trap is a chamber having an inlet and outlet opening which may be made to communicate with a chamber to be evacuated and a diffusion pump, respectively. A valve is designed to hermeticaliy seal with inlet opening and, when opened, block the line-of- sight'' between the inlet and outlet openings, while allowing a large flow path between the opened vaive and the side walls of the trap. The interior of the trap and the side of the valve facing the inlet opening are covered with an impurity absorbent, such as Zeolite or activated aluminum. Besides the advantage of combining two components of a vacuum system into one, the present invention removes the need for a baffle between the pump and the chamber to be evacuated. In one use of a specific embodiment of this invention, the transmission probability was 45 and the partial pressure of the pump fluid vapor in the vacuum chamber was at least 100 times lower than its vapor pressure. (AEC)

46 CFR 30.10-55 - Pressure vacuum relief valve-TB/ALL.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Pressure vacuum relief valve-TB/ALL. 30.10-55 Section 30... Definitions § 30.10-55 Pressure vacuum relief valve—TB/ALL. The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of...

46 CFR 30.10-55 - Pressure vacuum relief valve-TB/ALL.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 1 2014-10-01 2014-10-01 false Pressure vacuum relief valve-TB/ALL. 30.10-55 Section 30... Definitions § 30.10-55 Pressure vacuum relief valve—TB/ALL. The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of...

46 CFR 30.10-55 - Pressure vacuum relief valve-TB/ALL.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Pressure vacuum relief valve-TB/ALL. 30.10-55 Section 30... Definitions § 30.10-55 Pressure vacuum relief valve—TB/ALL. The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of...

46 CFR 30.10-55 - Pressure vacuum relief valve-TB/ALL.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Pressure vacuum relief valve-TB/ALL. 30.10-55 Section 30... Definitions § 30.10-55 Pressure vacuum relief valve—TB/ALL. The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of...

46 CFR 30.10-55 - Pressure vacuum relief valve-TB/ALL.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 1 2013-10-01 2013-10-01 false Pressure vacuum relief valve-TB/ALL. 30.10-55 Section 30... Definitions § 30.10-55 Pressure vacuum relief valve—TB/ALL. The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of...

The Mars Development of a Micro-Isolation Valve

NASA Technical Reports Server (NTRS)

Mueller, Juergen; Vargo, Steven; Forgrave, John; Bame, David; Chakraborty, Indrani; Tang, William

1999-01-01

A feasibility investigation for a newly proposed microfabricated, normally-closed isolation valve was initiated. The micro-isolation valve is silicon based and relies on the principle of melting a silicon plug, opening an otherwise sealed flow passage. This valve may thus serve a similar role as a conventional pyrovalve and is intended for use in micropropulsion systems onboard future microspacecraft, having wet masses of no more than 10-20 kg, as well as in larger scale propulsion systems having only low flow rate requirements, such as ion propulsion or Hall thruster systems. Two key feasibility issues - melting of the plug and pressure handling capability - were addressed. Thermal finite element modeling showed that valves with plugs having widths between 10 and 50 gm have power requirements of only 10 . 30 Watts to open over a duration of 0.5 ms or less. Valve chips featuring 5 0 micron plugs were burst pressure tested and reached maximum pressure values o f 2900 psig (19.7 Mpa).

40 CFR 60.482-6a - Standards: Open-ended valves or lines.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines... PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for..., Reconstruction, or Modification Commenced After November 7, 2006 § 60.482-6a Standards: Open-ended valves or...

Fluid-structure interaction dynamic simulation of spring-loaded pressure relief valves under seismic wave

NASA Astrophysics Data System (ADS)

Lv, Dongwei; Zhang, Jian; Yu, Xinhai

2018-05-01

In this paper, a fluid-structure interaction dynamic simulation method of spring-loaded pressure relief valve was established. The dynamic performances of the fluid regions and the stress and strain of the structure regions were calculated at the same time by accurately setting up the contact pairs between the solid parts and the coupling surfaces between the fluid regions and the structure regions. A two way fluid-structure interaction dynamic simulation of a simplified pressure relief valve model was carried out. The influence of vertical sinusoidal seismic waves on the performance of the pressure relief valve was preliminarily investigated by loading sine waves. Under vertical seismic waves, the pressure relief valve will flutter, and the reseating pressure was affected by the amplitude and frequency of the seismic waves. This simulation method of the pressure relief valve under vertical seismic waves can provide effective means for investigating the seismic performances of the valves, and make up for the shortcomings of the experiment.

Torque characteristics of a 122-centimeter butterfly valve with a hydro/pneumatic actuator

NASA Technical Reports Server (NTRS)

Lin, F. N.; Moore, W. I.; Lundy, F. E.

1981-01-01

Actuating torque data from field testing of a 122-centimeter (48 in.) butterfly valve with a hydro/pneumatic actuator is presented. The hydraulic cylinder functions as either a forward or a reverse brake. Its resistance torque increases when the valve speeds up and decreases when the valve slows down. A reduction of flow resistance in the hydraulic flow path from one end of the hydraulic cylinder to the other will effectively reduce the hydraulic resistance torque and hence increase the actuating torque. The sum of hydrodynamic and friction torques (combined resistance torque) of a butterfly valve is a function of valve opening time. An increase in the pneumatic actuating pressure will result in a decrease in both the combined resistance torque and the actuator opening torque; however, it does shorten the valve opening time. As the pneumatic pressure increases, the valve opening time for a given configuration approaches an asymptotical value.

Fast-acting valve actuator

DOEpatents

Cho, Nakwon

1980-01-01

A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

Flow compensating pressure regulator

NASA Technical Reports Server (NTRS)

Baehr, E. F. (Inventor)

1978-01-01

An apparatus for regulating pressure of treatment fluid during ophthalmic procedures is described. Flow sensing and pressure regulating diaphragms are used to modulate a flow control valve. The pressure regulating diaphragm is connected to the flow control valve to urge the valve to an open position due to pressure being applied to the diaphragm by bias means such as a spring. The flow sensing diaphragm is mechanically connected to the flow control valve and urges it to an opened position because of the differential pressure on the diaphragm generated by a flow of incoming treatment fluid through an orifice in the diaphragm. A bypass connection with a variable restriction is connected in parallel relationship to the orifice to provide for adjusting the sensitivity of the flow sensing diaphragm. A multiple lever linkage system is utilized between the center of the second diaphragm and the flow control valve to multiply the force applied to the valve by the other diaphragm and reverse the direction of the force.

Non-Pyrotechnic Zero-Leak Normally Closed Valve

NASA Technical Reports Server (NTRS)

Gillespie, Rebecca

2010-01-01

This valve is designed to create a zero-leak seal in a liquid propulsion system that is a functional replacement for the normally closed pyrovalve. Unlike pyrovalves, Nitinol is actuated by simply heating the material to a certain temperature, called the transition temperature. Like a pyrovalve, before actuation, the upstream and downstream sections are separated from one another and from the external environment by closed welded seals. Also like pyrovalves, after actuation, the propellant or pressurant gas can flow without a significant pressure drop but are still separated from the external environment by a closed welded seal. During manufacture, a Nitinol bar is compressed to 93 percent of its original length and fitted tightly into the valve. During operation, the valve is heated until the Nitinol reaches the transition temperature of 95 C; the Nitinol "remembers" its previous longer shape with a very large recovery force causing it to expand and break the titanium parent metal seal to allow flow. Once open, the valve forever remains open. The first prototype valve was designed for high pressure [5,000 psi (=34.5 MPa)] and low flow, typical requirements for pressurant gas valves in liquid propulsion systems. It is possible to modify the dimensions to make low-pressure models or high-flow models, for use downstream of the propellant tanks. This design is simpler, lower risk, and less expensive than the pyrovalve. Although the valve must be in a thermally controlled state (kept below 80 C) to prevent premature actuation, the pyrovalves and electrically actuated initiators have far more taxing handling requirements.

Liquid rocket pressure regulators, relief valves, check valves, burst disks, and explosive valves. [design techniques and practices

NASA Technical Reports Server (NTRS)

1973-01-01

The development of and operational programs for effective use in design are presented for liquid rocket pressure regulators, relief valves, check valves, burst disks, and explosive valves. A review of the total design problem is presented, and design elements are identified which are involved in successful design. Current technology pertaining to these elements is also described. Design criteria are presented which state what rule or standard must be imposed on each essential design element to assure successful design. These criteria serve as a checklist of rules for a project manager to use in guiding a design or in assessing its adequacy. Recommended practices are included which state how to satisfy each of the criteria.

Pseudolinear gradient ultrahigh-pressure liquid chromatography using an injection valve assembly.

PubMed

Xiang, Yanqiao; Liu, Yansheng; Stearns, Stanley D; Plistil, Alex; Brisbin, Martin P; Lee, Milton L

2006-02-01

The use of ultrahigh pressures in liquid chromatography (UHPLC) imposes stringent requirements on hardware such as pumps, valves, injectors, connecting tubing, and columns. One of the most difficult components of the UHPLC system to develop has been the sample injector. Static-split injection, which can be performed at pressures up to 6900 bar (100,000 psi), consumes a large sample volume and is very irreproducible. A pressure-balanced injection valve provided better reproducibility, shorter injection time, reduced sample consumption, and greater ease of use; however, it could only withstand pressures up to approximately 1000 bar (15,000 psi). In this study, a new injection valve assembly that can operate at pressures as high as 2070 bar (30,000 psi) was evaluated for UHPLC. This assembly contains six miniature electronically controlled needle valves to provide accurate and precise volumes for introduction into the capillary LC column. It was found that sample volumes as small as several tenths of a nanoliter can be injected, which are comparable to the results obtained from the static-split injector. The reproducibilities of retention time, efficiency, and peak area were investigated, and the results showed that the relative standard deviations of these parameters were small enough for quantitative analyses. Separation experiments using the UHPLC system with this new injection valve assembly showed that this new injector is suitable for both isocratic and gradient operation modes. A newly designed capillary connector was used at a pressure as high as 2070 bar (30,000 psi).

Self-Rupturing Hermetic Valve

NASA Technical Reports Server (NTRS)

Tucker, Curtis E., Jr.; Sherrit, Stewart

2011-01-01

-energizing and requires low force compared to current pyrotechnic-based burst disk hermetic valves. This is a novel design for producing a single-use, self-rupturing, hermetically sealed valve for isolation of pressurized gas and/or liquids. This design can also be applied for single-use disposable valves for chemical instruments. A welded foil diaphragm is fully supported by two mated surfaces that are machined to micron accuracies using EDM. To open the valve, one of the surfaces is moved relative to the other to (a) remove the support creating an unsupported diaphragm that ruptures due to over pressure, and/or (b) produce tension in the diaphragm and rupture it.

Rankine cycle condenser pressure control using an energy conversion device bypass valve

DOEpatents

Ernst, Timothy C; Nelson, Christopher R; Zigan, James A

2014-04-01

The disclosure provides a waste heat recovery system and method in which pressure in a Rankine cycle (RC) system of the WHR system is regulated by diverting working fluid from entering an inlet of an energy conversion device of the RC system. In the system, an inlet of a controllable bypass valve is fluidly coupled to a working fluid path upstream of an energy conversion device of the RC system, and an outlet of the bypass valve is fluidly coupled to the working fluid path upstream of the condenser of the RC system such that working fluid passing through the bypass valve bypasses the energy conversion device and increases the pressure in a condenser. A controller determines the temperature and pressure of the working fluid and controls the bypass valve to regulate pressure in the condenser.

SLM Produced Hermetically Sealed Isolation Valve

NASA Technical Reports Server (NTRS)

Richard, James

2014-01-01

Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic-driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic-based valve.

SLM Produced Hermetically Sealed Isolation Valve

NASA Technical Reports Server (NTRS)

Richard, James A.

2014-01-01

Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic based valve.

Monovalve with integrated fuel injector and port control valve, and engine using same

DOEpatents

Milam, David M.

2001-11-06

An engine includes an engine casing that defines a hollow piston cavity separated from an exhaust passage and an intake passage by a valve seat. A gas exchange valve member is positioned adjacent the valve seat and is moveable between an open position and a closed position. The gas exchange valve member also defines an opening that opens into the hollow piston cavity. A needle valve member is positioned in the gas exchange valve member adjacent a nozzle outlet and is moveable between an inject position and a blocked position. A port control valve member, which has a hydraulic surface, is mounted around the gas exchange valve member and moveable between an intake position and an exhaust position. A pilot valve is moveable between a first position at which the port control hydraulic surface is exposed to a source of high pressure fluid, and a second position at which the port control hydraulic surface is exposed to a source of low pressure fluid.

Direct-heating solar-collector dump valve

NASA Technical Reports Server (NTRS)

Howikman, T. C.

1977-01-01

Five-port ganged valve isolates collector from primary load system pressure and drains collectors, allowing use of direct heating with all its advantages. Valve is opened and closed by same switch that controls pump or by temperature sensor set at O C, while providing direct dump option.

Calibration of sonic valves for the laminar flow control, leading-edge flight test

NASA Technical Reports Server (NTRS)

Petley, D. H.; Alexander, W., Jr.; Wright, A. S., Jr.; Vallas, M.

1985-01-01

Sonic needle valves were calibrated to measure and control airflow in the suction system for the leading-edge flight test. The procedure and results for the calibration flow test of 4:41 flight valves are given. Mass-flow rates, which ranged from 0.001 to 0.012 lbm/sec, and maximum back pressure were measured for total temperatures from -30 F to 75 F and total pressures from 120 to 540 psf. Correlating equations are obtained for mass-flow rate as a function of total pressure, total temperature, and valve opening length. The most important aspect of flow measurement and control is found to be the measurement of valve opening length.

Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves.

PubMed

Johansen, Peter; Engholt, Henrik; Tang, Mariann; Nybo, Rasmus F; Rasmussen, Per D; Nielsen-Kudsk, Jens Erik

2017-10-13

Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, in smaller-sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study was to identify the fracture pressures needed in BHV, and to describe the fracture mechanics. Commonly used BHV of small sizes were mounted on a high-pressure balloon situated in a biplane fluoroscopic system with a high-speed camera. The instant of fracture was captured along with the balloon pressure. The valves were inspected for material protrusion and later dissected for fracture zone investigation and description. The valves with a polymer frame fractured at a lower pressure (8-10 atm) than those with a metal stent (19-26 atm). None of the fractured valves had elements protruding. VIV procedures in small-sized BHV may be performed after prior fracture of the valve frame by high-pressure balloon dilatation. This study provides tentative guidelines for expected balloon sizes and pressures for valve fracturing.

Consequences of intravascular lymphatic valve properties: a study of contraction timing in a multi-lymphangion model

PubMed Central

Macaskill, Charlie; Davis, Michael J.; Moore, James E.

2016-01-01

The observed properties of valves in collecting lymphatic vessels include transmural pressure-dependent bias to the open state and hysteresis. The bias may reduce resistance to flow when the vessel is functioning as a conduit. However, lymphatic pumping implies a streamwise increase in mean pressure across each valve, suggesting that the bias is then potentially unhelpful. Lymph pumping by a model of several collecting lymphatic vessel segments (lymphangions) in series, which incorporated these properties, was investigated under conditions of adverse pressure difference while varying the refractory period between active muscular contractions and the inter-lymphangion contraction delay. It was found that many combinations of the timing parameters and the adverse pressure difference led to one or more intermediate valves remaining open instead of switching between open and closed states during repetitive contraction cycles. Cyclic valve switching was reliably indicated if the mean pressure in a lymphangion over a cycle was higher than that in the lymphangion upstream, but either lack of or very brief valve closure could cause mean pressure to be lower downstream. Widely separated combinations of refractory period and delay time were found to produce the greatest flow-rate for a given pressure difference. The efficiency of pumping was always maximized by a long refractory period and lymphangion contraction starting when the contraction of the lymphangion immediately upstream was peaking. By means of an ex vivo experiment, it was verified that intermediate valves in a chain of pumping lymphangions can remain open, while the lymphangions on either side of the open valve continue to execute contractions. PMID:26747501

Assessment of trans-aortic pressure gradient using a coronary pressure wire in patients with mechanical aortic and mitral valve prostheses.

PubMed

Kherada, Nisharahmed; Brenes, Juan Carlos; Kini, Annapoorna S; Dangas, George D

2017-03-15

Accurate evaluation of trans-aortic valvular pressure gradients is challenging in cases where dual mechanical aortic and mitral valve prostheses are present. Non-invasive Doppler echocardiographic imaging has its limitations due to multiple geometric assumptions. Invasive measurement of trans-valvular gradients with cardiac catheterization can provide further information in patients with two mechanical valves, where simultaneous pressure measurements in the left ventricle and ascending aorta must be obtained. Obtaining access to the left ventricle via the mitral valve after a trans-septal puncture is not feasible in the case of a concomitant mechanical mitral valve, whereas left ventricular apical puncture technique is associated with high procedural risks. Retrograde crossing of a bileaflet mechanical aortic prosthesis with standard catheters is associated with the risk of catheter entrapment and acute valvular regurgitation. In these cases, the assessment of trans-valvular gradients using a 0.014˝ diameter coronary pressure wire technique has been described in a few case reports. We present the case of a 76-year-old female with rheumatic valvular heart disease who underwent mechanical aortic and mitral valve replacement in the past. She presented with decompensated heart failure and echocardiographic findings suggestive of elevated pressure gradient across the mechanical aortic valve prosthesis. The use of a high-fidelity 0.014˝ diameter coronary pressure guidewire resulted in the detection of a normal trans-valvular pressure gradient across the mechanical aortic valve. This avoided a high-risk third redo valve surgery in our patient. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Numerical investigation of cavitation flow inside spool valve with large pressure drop

NASA Astrophysics Data System (ADS)

Deng, Jian; Pan, Dingyi; Xie, Fangfang; Shao, Xueming

2015-12-01

Spool valves play an important role in fluid power system. Cavitation phenomena happen frequently inside the spool valves, which cause structure damages, noise and lower down hydrodynamic performance. A numerical tools incorporating the cavitation model, are developed to predict the flow structure and cavitation pattern in the spool valve. Two major flow states in the spool valve chamber, i.e. flow-in and flow-out, are studies. The pressure distributions along the spool wall are first investigated, and the results agree well with the experimental data. For the flow-in cases, the local pressure at the throttling area drops much deeper than the pressure in flow-out cases. Meanwhile, the bubbles are more stable in flow-in cases than those in flow-out cases, which are ruptured and shed into the downstream.

Orthogonal optimization of a water hydraulic pilot-operated pressure-reducing valve

NASA Astrophysics Data System (ADS)

Mao, Xuyao; Wu, Chao; Li, Bin; Wu, Di

2017-12-01

In order to optimize the comprehensive characteristics of a water hydraulic pilot-operated pressure-reducing valve, numerical orthogonal experimental design was adopted. Six parameters of the valve, containing diameters of damping plugs, volume of spring chamber, half cone angle of main spool, half cone angle of pilot spool, mass of main spool and diameter of main spool, were selected as the orthogonal factors, and each factor has five different levels. An index of flowrate stability, pressure stability and pressure overstrike stability (iFPOS) was used to judge the merit of each orthogonal attempt. Embedded orthogonal process turned up and a final optimal combination of these parameters was obtained after totally 50 numerical orthogonal experiments. iFPOS could be low to a fairly low value which meant that the valve could have much better stabilities. During the optimization, it was also found the diameters of damping plugs and main spool played important roles in stability characteristics of the valve.

Pressure compensated flow control valve

DOEpatents

Minteer, Daniel J.

1999-01-01

The invention is an air flow control valve which is capable of maintaining a constant flow at the outlet despite changes in the inlet or outlet pressure. The device consists of a shell assembly with an inlet chamber and outlet chamber separated by a separation plate. The chambers are connected by an orifice. Also located within the inlet chamber is a port controller assembly. The port controller assembly consists of a differential pressure plate and port cap affixed thereon. The cap is able to slide in and out of the orifice separating the inlet and outlet chambers. When the pressure differential is sufficient, the differential pressure plate rises or falls to maintain a constant air flow. Movement of the port controller assembly does not require the use of seals, diaphragms, tight tolerances, bushings, bearings, hinges, guides, or lubricants.

Extrinsic mechanism obstructing the opening of a prosthetic mitral valve: an unusual case of suture entrapment.

PubMed

Ozkan, Mehmet; Astarcioglu, Mehmet Ali; Karakoyun, Suleyman; Balkanay, Mehmet

2012-02-01

Obstruction to a prosthetic cardiac valve is a well-recognized complication of cardiac valve replacement. Malfunction of the mobile component of a prosthetic valve to open or close correctly may occur in consequence of intrinsic or extrinsic causes (thrombus, vegetation, entrapment of left ventricular myocardium, suture entanglement, and pannus formation) that may result prosthetic valve stenosis and/or insufficiency. In the case we report a 48-year-old female with valve dysfunction occurred early after surgery, as one valve leaflet was only able to partially open due to suture entrapment. © 2011, Wiley Periodicals, Inc.

Pressure model of a four-way spool valve for simulating electrohydraulic control systems

NASA Technical Reports Server (NTRS)

Gebben, V. D.

1976-01-01

An equation that relates the pressure flow characteristics of hydraulic spool valves was developed. The dependent variable is valve output pressure, and the independent variables are spool position and flow. This causal form of equation is preferred in applications that simulate the effects of hydraulic line dynamics. Results from this equation are compared with those from the conventional valve equation, whose dependent variable is flow. A computer program of the valve equations includes spool stops, leakage spool clearances, and dead-zone characteristics of overlap spools.

Engine Cycle Analysis of Air Breathing Microwave Rocket with Reed Valves

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

Fukunari, Masafumi; Komatsu, Reiji; Yamaguchi, Toshikazu

The Microwave Rocket is a candidate for a low cost launcher system. Pulsed plasma generated by a high power millimeter wave beam drives a blast wave, and a vehicle acquires impulsive thrust by exhausting the blast wave. The thrust generation process of the Microwave Rocket is similar to a pulse detonation engine. In order to enhance the performance of its air refreshment, the air-breathing mechanism using reed valves is under development. Ambient air is taken to the thruster through reed valves. Reed valves are closed while the inside pressure is high enough. After the time when the shock wave exhaustsmore » at the open end, an expansion wave is driven and propagates to the thrust-wall. The reed valve is opened by the negative gauge pressure induced by the expansion wave and its reflection wave. In these processes, the pressure oscillation is important parameter. In this paper, the pressure oscillation in the thruster was calculated by CFD combined with the flux through from reed valves, which is estimated analytically. As a result, the air-breathing performance is evaluated using Partial Filling Rate (PFR), the ratio of thruster length to diameter L/D, and ratio of opening area of reed valves to superficial area {alpha}. An engine cycle and predicted thrust was explained.« less

High-pressure cryogenic valves for the Vulcain rocket motor

NASA Astrophysics Data System (ADS)

Garceau, P.; Meyer, F.

The high-pressure valve developed to control the flow of liquid oxygen or hydrogen into the gas generator of the ESA Vulcain rocket motor is described. The spherical ball-seal design employed provides high reliability over a service lifetime of 5000 on-off actuations at temperatures 20-350 K and pressures up to 200 bar. Leakage is limited to a few cu cm/sec of hydrogen at 20 K. The steps in the development process, from the definition of the valve specifications to the fabrication and testing phase are reviewed, and the final design is shown in drawings, diagrams, and photographs.

Discontinuous atmospheric pressure interface for mass spectrometry using a solenoid pulse valve.

PubMed

Usmanov, Dilshadbek T; Hiraoka, Kenzo

2016-08-30

For the development of on-site mass spectrometry for security and safety, point-of-care analysis, etc., the gas volume introduced into the vacuum should be reduced to a minimum. To cope with this demand, a discontinuous atmospheric pressure interface using a solenoid pulse valve was developed. The sample gas was introduced discontinuously into the ionization cell with a volume of 0.17 cm(3) . The sampled gas in the cell was ionized by an alternating current (ac) corona discharge. The generated ions were sampled through a 0.25 mm i.d. and 12 mm long nickel capillary into the vacuum of a time-of-flight mass spectrometer. A gas flow rate of ~25 mL/min was achieved with the 1 Hz pulse valve operation and 20 ms valve opening time. Sub-ng limits of detection for less volatile compounds such as explosives and drugs were obtained. Due to its compact size and low gas load to the vacuum, this new interface may be useful for applications in miniaturized mass spectrometry. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

System for detecting operating errors in a variable valve timing engine using pressure sensors

DOEpatents

Wiles, Matthew A.; Marriot, Craig D

2013-07-02

A method and control module includes a pressure sensor data comparison module that compares measured pressure volume signal segments to ideal pressure volume segments. A valve actuation hardware remedy module performs a hardware remedy in response to comparing the measured pressure volume signal segments to the ideal pressure volume segments when a valve actuation hardware failure is detected.

Pressure variable orifice for hydraulic control valve

NASA Technical Reports Server (NTRS)

Ammerman, R. L.

1968-01-01

Hydraulic valve absorbs impact energy generated in docking or joining of two large bodies by controlling energy release to avoid jarring shock. The area of exit porting presented to the hydraulic control fluid is directly proportional to the pressure acting on the fluid.

High cleanliness globe valve with sine mechanism drive

NASA Astrophysics Data System (ADS)

Luo, Hu

2018-06-01

This paper gives a new type of quick-opening globe valve for life support pneumatic control system of the safety cabin at underground coal mine. The valve adopts the sine mechanism to transmit the rotating of the handle in the range of 90° to the reciprocating motion of the spool. The mechanism implements the quick-opening function of the valve through controlling the contact and separation between the O-ring and the end face of the valve. Since there is no relative sliding between the sealing interfaces, the valve solute uncontrollable disadvantage wear particles which produced by package ball valve, to ensure high cleanliness in flow path. Traditional transmission mechanism has a reinforcement effect and reduce handle open torque. By the finite element method, the relationship between the contact force and the compression of O-ring is analyzed to provide the boundary condition for the calculation of the rotational torque. Meanwhile the velocity field and pressure field along the flow path are simulated. The caliber size of the valve and the flow resistance coefficient are obtained. There is higher cleanliness, more reliable sealing, smaller handle open torque advantage compared with existing packing ball valve. The above work presents a new technical approach for the design of pneumatic control valve of the safety cabin.

40 CFR 63.1033 - Open-ended valves or lines standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Open-ended valves or lines standards... PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National Emission Standards for Equipment Leaks-Control Level 2 Standards § 63.1033 Open-ended...

Reed Valve Regulates Welding Back-Purge Pressure

NASA Technical Reports Server (NTRS)

Coby, J. Ben, Jr.; Weeks, Jack L.

1991-01-01

Simple modification yields welds of better quality. Reed valve halves fluctuations in pressure in back-purge chamber attached to workpiece undergoing keyhole plasma arc welding. Identical to one used in fuel system of two-cycle gasoline engine. Backbead smoother, and weld penetrates more uniformly.

46 CFR 52.20-17 - Opening between boiler and safety valve (modifies PFT-44).

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Opening between boiler and safety valve (modifies PFT-44). 52.20-17 Section 52.20-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS Requirements for Firetube Boilers § 52.20-17 Opening between boiler and safety valve...

46 CFR 52.20-17 - Opening between boiler and safety valve (modifies PFT-44).

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Opening between boiler and safety valve (modifies PFT-44). 52.20-17 Section 52.20-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS Requirements for Firetube Boilers § 52.20-17 Opening between boiler and safety valve...

46 CFR 52.20-17 - Opening between boiler and safety valve (modifies PFT-44).

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Opening between boiler and safety valve (modifies PFT-44). 52.20-17 Section 52.20-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS Requirements for Firetube Boilers § 52.20-17 Opening between boiler and safety valve...

46 CFR 52.20-17 - Opening between boiler and safety valve (modifies PFT-44).

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Opening between boiler and safety valve (modifies PFT-44). 52.20-17 Section 52.20-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS Requirements for Firetube Boilers § 52.20-17 Opening between boiler and safety valve...

46 CFR 52.20-17 - Opening between boiler and safety valve (modifies PFT-44).

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Opening between boiler and safety valve (modifies PFT-44). 52.20-17 Section 52.20-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS Requirements for Firetube Boilers § 52.20-17 Opening between boiler and safety valve...

Micro system comprising 96 micro valves on a titer plate

NASA Astrophysics Data System (ADS)

Krabbe, S.; Flitsch, D.; Büchs, J.; Schomburg, W. K.

2016-10-01

A system of 96 micro valves has been developed and mounted on top of a 48-well micro titer plate providing two valves for each well controlling its air inlet and outlet. Testing of the valve system showed that all valves are working and are opened and closed reliably. A pneumatic system is switching inlet and outlet valves independently of each other. The geometry of the feed channels ensures an equal air flow through all wells, when the valves are open. Between the micro valves, one optical fibre was inserted through the lid of each well allowing measuring the oxygen partial pressure in the enclosed air volume by fluorescence sensor spots. Escherichia coli bacteria were grown inside the wells and their metabolism was observed by the oxygen partial pressure change due to respiration. In all 48 wells, the same oxygen transfer rate was observed within an averaged standard deviation of 1 mmol/L/h. The oxygen transfer rate differences compared to a macroscopic standard shake flask system were overall compatible within their uncertainties.

Myocardial Protection and Financial Considerations of Custodiol Cardioplegia in Minimally Invasive and Open Valve Surgery.

PubMed

Hummel, Brian W; Buss, Randall W; DiGiorgi, Paul L; Laviano, Brittany N; Yaeger, Nalani A; Lucas, M Lee; Comas, George M

Single-dose antegrade crystalloid cardioplegia with Custodiol-HTK (histidine-tryptophan-ketoglutarate) has been used for many years. Its safety and efficacy were established in experimental and clinical studies. It is beneficial in complex valve surgery because it provides a long period of myocardial protection with a single dose. Thus, valve procedures (minimally invasive or open) can be performed with limited interruption. The aim of this study is to compare the use of Custodiol-HTK cardioplegia with traditional blood cardioplegia in patients undergoing minimally invasive and open valve surgery. A single-institution, retrospective case-control review was performed on patients who underwent valve surgery in Lee Memorial Health System at either HealthPark Medical Center or Gulf Coast Medical Center from July 1, 2011, through March 7, 2015. A total of 181 valve cases (aortic or mitral) performed using Custodiol-HTK cardioplegia were compared with 181 cases performed with traditional blood cardioplegia. Each group had an equal distribution of minimally invasive and open valve cases. Right chest thoracotomy or partial sternotomy was performed on minimally invasive valve cases. Demographics, perioperative data, clinical outcomes, and financial data were collected and analyzed. Patient outcomes were superior in the Custodiol-HTK cardioplegia group for blood transfusion, stroke, and hospital readmission within 30 days (P < 0.05). No statistical differences were observed in the other outcomes categories. Hospital charges were reduced on average by $3013 per patient when using Custodiol-HTK cardioplegia. Use of Custodiol-HTK cardioplegia is safe and cost-effective when compared with traditional repetitive blood cardioplegia in patients undergoing minimally invasive and open valve surgery.

PMMA/PDMS valves and pumps for disposable microfluidics.

PubMed

Zhang, Wenhua; Lin, Shuichao; Wang, Chunming; Hu, Jia; Li, Cong; Zhuang, Zhixia; Zhou, Yongliang; Mathies, Richard A; Yang, Chaoyong James

2009-11-07

Poly(methyl methacrylate) (PMMA) is gaining in popularity in microfluidic devices because of its low cost, excellent optical transparency, attractive mechanical/chemical properties, and simple fabrication procedures. It has been used to fabricate micromixers, PCR reactors, CE and many other microdevices. Here we present the design, fabrication, characterization and application of pneumatic microvalves and micropumps based on PMMA. Valves and pumps are fabricated by sandwiching a PDMS membrane between PMMA fluidic channel and manifold wafers. Valve closing or opening can be controlled by adjusting the pressure in a displacement chamber on the pneumatic layer via a computer regulated solenoid. The valve provides up to 15.4 microL s(-1) at 60 kPa fluid pressure and seals reliably against forward fluid pressure as high as 60 kPa. A PMMA diaphragm pump can be assembled by simply connecting three valves in series. By varying valve volume or opening time, pumping rates ranging from nL to microL per second can be accurately achieved. The PMMA based valves and pumps were further tested in a disposable automatic nucleic acid extraction microchip to extract DNA from human whole blood. The DNA extraction efficiency was about 25% and the 260 nm/280 nm UV absorption ratio for extracted DNA was 1.72. Because of its advantages of inexpensive, facile fabrication, robust and easy integration, the PMMA valve and pump will find their wide application for fluidic manipulation in portable and disposable microfluidic devices.

Pressure Regulators as Valves for Saving Compressed Air and their Influence on System Dynamics

NASA Astrophysics Data System (ADS)

Dvořák, Lukáš; Fojtášek, Kamil

2015-05-01

Pressure regulators in the field of pneumatic mechanisms can be used as valves for saving compressed air. For example it can be used to reduce the pressure when the piston rod is retracting unloaded and thus it is possible to save some energy. However the problem is that saving valve can significantly affect the dynamics of the pneumatic system. The lower pressure in the piston rod chamber causes extension of time for retraction of the piston rod. This article compare the air consumption experimentally determined and calculated, measured curves of pressure in cylinder chambers and piston speed when saving valve is set up differently.

Refuge alternatives relief valve testing and design with updated test stand.

PubMed

Lutz, T J; Bissert, P T; Homce, G T; Yonkey, J A

2018-03-01

Underground refuge alternatives require an air source to supply breathable air to the occupants. This requires pressure relief valves to prevent unsafe pressures from building up within the refuge alternative. The U.S. Mine Safety and Health Administration (MSHA) mandates that pressure relief valves prevent pressure from exceeding 1.25 kPa (0.18 psi), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. The U.S. National Institute for Occupational Safety and Health (NIOSH) tested a variety of pressure relief valves using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork and various sensors to determine if the subject pressure relief valves meet the MSHA requirement. Relief pressures and flow characteristics, including opening pressure and flow rate, were measured for five different pressure relief valves under a variety of conditions. The subject pressure relief valves included two off-the-shelf modified check valves, two check valves used in MSHA-approved built-in-place refuge alternatives, and a commercially available valve that was designed for a steel refuge alternative and is currently being used in some built-in-place refuge alternatives. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.03 to 0.22 psi) and flow rates up to 19.3 m 3 /min (683 scfm). As tested, some of the pressure relief valves did not meet the 1.25 kPa (0.18 psi) relief specification.

Refuge alternatives relief valve testing and design with updated test stand

PubMed Central

Lutz, T.J.; Bissert, P.T.; Homce, G.T.; Yonkey, J.A.

2018-01-01

Underground refuge alternatives require an air source to supply breathable air to the occupants. This requires pressure relief valves to prevent unsafe pressures from building up within the refuge alternative. The U.S. Mine Safety and Health Administration (MSHA) mandates that pressure relief valves prevent pressure from exceeding 1.25 kPa (0.18 psi), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. The U.S. National Institute for Occupational Safety and Health (NIOSH) tested a variety of pressure relief valves using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork and various sensors to determine if the subject pressure relief valves meet the MSHA requirement. Relief pressures and flow characteristics, including opening pressure and flow rate, were measured for five different pressure relief valves under a variety of conditions. The subject pressure relief valves included two off-the-shelf modified check valves, two check valves used in MSHA-approved built-in-place refuge alternatives, and a commercially available valve that was designed for a steel refuge alternative and is currently being used in some built-in-place refuge alternatives. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.03 to 0.22 psi) and flow rates up to 19.3 m3/min (683 scfm). As tested, some of the pressure relief valves did not meet the 1.25 kPa (0.18 psi) relief specification. PMID:29563650

Note: An improved solenoid driver valve for miniature shock tubes.

PubMed

Lynch, P T

2016-05-01

A solenoid driver valve has been built to improve the operating performance of diaphragmless shock tubes, which are used for high pressure, high temperature chemical kinetics, and fluid mechanics studies. For shock tube driver application, the most important characteristics are those of sealing, strength, and quality of the generated shock waves and repeatability of opening characteristics and therefore subsequent post-shock conditions. The main features of the new driver valve are a face o-ring sealing design of the valve, the large internal volume, and through inserts near the solenoid core: adjustable opening characteristics of the valve.

A High Pressure Pulsed Expansion Valve for Gases, Liquids, and Supercritical Fluids

NASA Astrophysics Data System (ADS)

Köster, C.; Grotemeyer, J.; Schlag, E. W.

1990-12-01

A novel design of a pulsed valve for coupling chromatographic techniques with gaseous and liquid mobile phases to a time-of-flight mass spectrometer with multiphoton ionization (MUPI) is presented. The valve can be operated in low pressure regions ( <10 bar) up to temperatures of 350 °C and at higher pressures (300 bar) up to temperatures of 200 °C. Pulse widths lower than 100 μs could be measured. First results demonstrate the ability of interfacing of liquid chromatography to MUPI-mass spectrometry. Additional coupling of CO2-laser desorption to the valve allows the interface to be used for mass spectrometric measurements of nonvolatile biomolecules.

Adding a custom made pressure release valve during air enema for intussusception: A new technique.

PubMed

Ahmed, Hosni Morsi; Ahmed, Osama; Ahmed, Refaat Khodary

2015-01-01

Non-surgical reduction remains the first line treatment of choice for intussusception. The major complication of air enema reduction is bowel perforation. The authors developed a custom made pressure release valve to be added to portable insufflation devices, delivering air at pressures accepted as safe for effective reduction of intussusception in children under fluoroscopic guidance. The aim of this study was to develop a custom made pressure release valve that is suitable for the insufflation devices used for air enema reduction of intussusception and to put this valve into regular clinical practice. An adjustable, custom made pressure release valve was assembled by the authors using readily available components. The valve was coupled to a simple air enema insufflation device. The device was used for the trial of reduction of intussusception in a prospective study that included 132 patients. The success rate for air enema reduction with the new device was 88.2%. The mean pressure required to achieve complete reduction was 100 mmHg. The insufflation pressure never exceeded the preset value (120 mmHg). Of the successful cases, 58.3% were reduced from the first attempt while 36.1% required a second insufflation. Only 5.55% required a third insufflation to complete the reduction. In cases with unsuccessful pneumatic reduction attempt (18.1%), surgical treatment was required. Surgery ranged from simple reduction to resection with a primary end to end anastomosis. No complications from air enema were recorded. The authors recommend adding pressure release valves to ensure safety by avoiding pressure overshoot during the procedure.

Ten years of clinical experience in the use of fixed-pressure versus programmable valves: a retrospective study of 159 patients.

PubMed

Mpakopoulou, Maria; Brotis, Alexandros G; Gatos, Haralampos; Paterakis, Konstantinos; Fountas, Kostas N

2012-01-01

The aim of this study was to present our 10-year experience with the use of fixed-pressure and programmable valves in the treatment of adult patients requiring cerebrospinal fluid (CSF) diversion. Patients (n = 159; 89 male and 70 female) suffering from hydrocephalus of various causes underwent CSF shunt implantation. Forty fixed-pressure and 119 programmable valves were initially implanted. The observed revision rate was 40% in patients with fixed-pressure valves. In 20% of these patients, a revision due to valve mechanism malfunction was undertaken, and the initial valve was replaced with a programmable one. The revision rate in the adjustable-pressure valve subgroup was 20%. The infection rate for the fixed-pressure and programmable valve subgroups were 3%, and 1.7%, respectively. Similarly, subdural fluid collections were noticed in 17% and 4% of patients with fixed-pressure valves and programmable valves, respectively. The revision and over-drainage rates were significantly lower when using programmable valves, and thus, this type of valve is preferred whenever CSF has to be diverted.

Hydraulically actuated gas exchange valve assembly and engine using same

DOEpatents

Carroll, Thomas S.; Taylor, Gregory O.

2002-09-03

An engine comprises a housing that defines a hollow piston cavity that is separated from a gas passage by a valve seat. The housing further defines a biasing hydraulic cavity and a control hydraulic cavity. A gas valve member is also included in the engine and is movable relative to the valve seat between an open position at which the hollow piston cavity is open to the gas passage and a closed position in which the hollow piston cavity is blocked from the gas passage. The gas valve member includes a ring mounted on a valve piece and a retainer positioned between the ring and the valve piece. A closing hydraulic surface is included on the gas valve member and is exposed to liquid pressure in the biasing hydraulic cavity.

Vent-induced prosthetic leaflet thrombosis treated by open-heart valve-in-valve implantation.

PubMed

Stamm, Christof; Pasic, Miralem; Buz, Semih; Hetzer, Roland

2015-09-01

A patient required emergency mitral valve replacement and extracorporeal membrane oxygenation (ECMO) support for acute biventricular failure. The left ventricular (LV) vent inserted via the left upper pulmonary vein induced thrombotic immobilization of a prosthetic valve leaflet, with significant intra-prosthesis regurgitation after ECMO explantation. Therefore, the left atrium was opened on the beating heart during conventional extracorporeal circulation, all prosthesis leaflets were excised and a 29-mm expandable Edwards Sapien prosthesis was inserted within the scaffold of the original prosthesis under direct vision. This case illustrates the benefits and potential problems of LV venting on ECMO support, and a rapid and safe way of replacing the prosthesis leaflets in a critical situation. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Conical Seat Shut-Off Valve

NASA Technical Reports Server (NTRS)

Farner, Bruce

2013-01-01

A moveable valve for controlling flow of a pressurized working fluid was designed. This valve consists of a hollow, moveable floating piston pressed against a stationary solid seat, and can use the working fluid to seal the valve. This open/closed, novel valve is able to use metal-to-metal seats, without requiring seat sliding action; therefore there are no associated damaging effects. During use, existing standard high-pressure ball valve seats tend to become damaged during rotation of the ball. Additionally, forces acting on the ball and stem create large amounts of friction. The combination of these effects can lead to system failure. In an attempt to reduce damaging effects and seat failures, soft seats in the ball valve have been eliminated; however, the sliding action of the ball across the highly loaded seat still tends to scratch the seat, causing failure. Also, in order to operate, ball valves require the use of large actuators. Positioning the metal-to-metal seats requires more loading, which tends to increase the size of the required actuator, and can also lead to other failures in other areas such as the stem and bearing mechanisms, thus increasing cost and maintenance. This novel non-sliding seat surface valve allows metal-to-metal seats without the damaging effects that can lead to failure, and enables large seating forces without damaging the valve. Additionally, this valve design, even when used with large, high-pressure applications, does not require large conventional valve actuators and the valve stem itself is eliminated. Actuation is achieved with the use of a small, simple solenoid valve. This design also eliminates the need for many seals used with existing ball valve and globe valve designs, which commonly cause failure, too. This, coupled with the elimination of the valve stem and conventional valve actuator, improves valve reliability and seat life. Other mechanical liftoff seats have been designed; however, they have only resulted in

Vacuum breaker valve assembly

DOEpatents

Thompson, J.L.; Upton, H.A.

1999-04-27

Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening. 1 fig.

Vacuum breaker valve assembly

DOEpatents

Thompson, Jeffrey L.; Upton, Hubert Allen

1999-04-27

Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening.

Mitral valve surgery - open

MedlinePlus

... place. There are two types of mitral valves: Mechanical, made of man-made (synthetic) materials, such as ... Mechanical heart valves last a lifetime. However, blood clots may develop on them. This can cause them ...

Medications for Heart Valve Symptoms

MedlinePlus

... on the heart Vasodilators Can lower the heart's work by opening and relaxing the blood vessels; reduced pressure may encourage blood to flow in a forward direction, rather than being forced backward through a leaky valve Additional resources: Print ...

Optimization of a pressure control valve for high power automatic transmission considering stability

NASA Astrophysics Data System (ADS)

Jian, Hongchao; Wei, Wei; Li, Hongcai; Yan, Qingdong

2018-02-01

The pilot-operated electrohydraulic clutch-actuator system is widely utilized by high power automatic transmission because of the demand of large flowrate and the excellent pressure regulating capability. However, a self-excited vibration induced by the inherent non-linear characteristics of valve spool motion coupled with the fluid dynamics can be generated during the working state of hydraulic systems due to inappropriate system parameters, which causes sustaining instability in the system and leads to unexpected performance deterioration and hardware damage. To ensure a stable and fast response performance of the clutch actuator system, an optimal design method for the pressure control valve considering stability is proposed in this paper. A non-linear dynamic model of the clutch actuator system is established based on the motion of the valve spool and coupling fluid dynamics in the system. The stability boundary in the parameter space is obtained by numerical stability analysis. Sensitivity of the stability boundary and output pressure response time corresponding to the valve parameters are identified using design of experiment (DOE) approach. The pressure control valve is optimized using particle swarm optimization (PSO) algorithm with the stability boundary as constraint. The simulation and experimental results reveal that the optimization method proposed in this paper helps in improving the response characteristics while ensuring the stability of the clutch actuator system during the entire gear shift process.

The patient inflating valve in anaesthesia and resuscitation breathing systems.

PubMed

Fenton, P M; Bell, G

2013-03-01

Patient inflating valves combined with self-inflating bags are known to all anaesthetists as resuscitation devices and are familiar as components of draw-over anaesthesia systems. Their variants are also commonplace in transfer and home ventilators. However, the many variations in structure and function have led to difficulties in their optimal use, definition and classification. After reviewing the relevant literature, we defined a patient inflating valve as a one-way valve that closes an exit port to enable lung inflation, also permitting exhalation and spontaneous breathing, the actions being automatic. We present a new classification based on the mechanism of valve opening/closure; namely elastic recoil of a flexible flap/diaphragm, sliding spindle opened by a spring/magnet or a hollow balloon collapsed by external pressure. The evolution of these valves has been driven by the difficulties documented in critical incidents, which we have used along with information from modern International Organization for Standardization standards to identify 13 ideal properties, the top six of which are non-jamming, automatic, no bypass effect, no rebreathing or air entry at patient end, low resistance, robust and easy to service. The Ambu and the Laerdal valves have remained popular due to their simplicity and reliability. Two new alternatives, the Fenton and Diamedica valves, offer the benefits of location away from the patient while retaining a small functional dead space. They also offer the potential for greater use of hybrid continuous flow/draw-over systems that can operate close to atmospheric pressure. The reliable application of positive end-expiratory pressure/continuous positive airway pressure remains a challenge.

Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement.

PubMed

Chhatriwalla, Adnan K; Allen, Keith B; Saxon, John T; Cohen, David J; Aggarwal, Sanjeev; Hart, Anthony J; Baron, Suzanne J; Dvir, Danny; Borkon, A Michael

2017-07-01

Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P <0.001) and an increase in valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P <0.001). No procedural complications were reported. BVF can be performed safely in small surgical valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area. © 2017 American Heart Association, Inc.

Rotary-To-Axial Motion Converter For Valve

NASA Technical Reports Server (NTRS)

Reinicke, Robert H.; Mohtar, Rafic

1991-01-01

Nearly frictionless mechanism converts rotary motion into axial motion. Designed for use in electronically variable pressure-regulator valve. Changes rotary motion imparted by motor into translation that opens and closes valve poppet. Cables spaced equidistantly around edge of fixed disk support movable disk. As movable disk rotated, cables twist, lifting it. When rotated in opposite direction, cables untwist, lowering it. Spider disk helps to prevent cables from tangling. Requires no lubrication and insensitive to contamination in fluid flowing through valve.

Sliding-gate valve for use with abrasive materials

DOEpatents

Ayers, Jr., William J.; Carter, Charles R.; Griffith, Richard A.; Loomis, Richard B.; Notestein, John E.

1985-01-01

The invention is a flow and pressure-sealing valve for use with abrasive solids. The valve embodies special features which provide for long, reliable operating lifetimes in solids-handling service. The valve includes upper and lower transversely slidable gates, contained in separate chambers. The upper gate provides a solids-flow control function, whereas the lower gate provides a pressure-sealing function. The lower gate is supported by means for (a) lifting that gate into sealing engagement with its seat when the gate is in its open and closed positions and (b) lowering the gate out of contact with its seat to permit abrasion-free transit of the gate between its open and closed positions. When closed, the upper gate isolates the lower gate from the solids. Because of this shielding action, the sealing surface of the lower gate is not exposed to solids during transit or when it is being lifted or lowered. The chamber containing the lower gate normally is pressurized slightly, and a sweep gas is directed inwardly across the lower-gate sealing surface during the vertical translation of the gate.

High-speed pressure clamp.

PubMed

Besch, Stephen R; Suchyna, Thomas; Sachs, Frederick

2002-10-01

We built a high-speed, pneumatic pressure clamp to stimulate patch-clamped membranes mechanically. The key control element is a newly designed differential valve that uses a single, nickel-plated piezoelectric bending element to control both pressure and vacuum. To minimize response time, the valve body was designed with minimum dead volume. The result is improved response time and stability with a threefold decrease in actuation latency. Tight valve clearances minimize the steady-state air flow, permitting us to use small resonant-piston pumps to supply pressure and vacuum. To protect the valve from water contamination in the event of a broken pipette, an optical sensor detects water entering the valve and increases pressure rapidly to clear the system. The open-loop time constant for pressure is 2.5 ms for a 100-mmHg step, and the closed-loop settling time is 500-600 micros. Valve actuation latency is 120 micros. The system performance is illustrated for mechanically induced changes in patch capacitance.

40 CFR 65.114 - Standards: Open-ended valves or lines.

Code of Federal Regulations, 2010 CFR

2010-07-01

... closed. (3) When a double block and bleed system is being used, the bleed valve or line may remain open... block and bleed system as specified in paragraph (b) of this section are exempt from the requirements of...

Mathematical multi-scale model of the cardiovascular system including mitral valve dynamics. Application to ischemic mitral insufficiency

PubMed Central

2011-01-01

Background Valve dysfunction is a common cardiovascular pathology. Despite significant clinical research, there is little formal study of how valve dysfunction affects overall circulatory dynamics. Validated models would offer the ability to better understand these dynamics and thus optimize diagnosis, as well as surgical and other interventions. Methods A cardiovascular and circulatory system (CVS) model has already been validated in silico, and in several animal model studies. It accounts for valve dynamics using Heaviside functions to simulate a physiologically accurate "open on pressure, close on flow" law. However, it does not consider real-time valve opening dynamics and therefore does not fully capture valve dysfunction, particularly where the dysfunction involves partial closure. This research describes an updated version of this previous closed-loop CVS model that includes the progressive opening of the mitral valve, and is defined over the full cardiac cycle. Results Simulations of the cardiovascular system with healthy mitral valve are performed, and, the global hemodynamic behaviour is studied compared with previously validated results. The error between resulting pressure-volume (PV) loops of already validated CVS model and the new CVS model that includes the progressive opening of the mitral valve is assessed and remains within typical measurement error and variability. Simulations of ischemic mitral insufficiency are also performed. Pressure-Volume loops, transmitral flow evolution and mitral valve aperture area evolution follow reported measurements in shape, amplitude and trends. Conclusions The resulting cardiovascular system model including mitral valve dynamics provides a foundation for clinical validation and the study of valvular dysfunction in vivo. The overall models and results could readily be generalised to other cardiac valves. PMID:21942971

[Atrio-ventricular pressure difference associated with mitral valve motion].

PubMed

Wang, L M; Mori, H; Minezaki, K; Shinozaki, Y; Okino, H

1990-05-01

Pressure difference (PD) across the mitral valve was analyzed by a computer-aided catheter system in dogs. Positive PD (PPD) was consistently traced in the initial phase of rapid filling. While heart rate (HR) was below 100 beat/min, a negative PD (NPD) followed the above PPD. In the period between the NPD and the 2nd PPD due to atrial contraction, PD was kept at zero, while LA and LV pressures were gradually elevated by pulmonary venous return. As HR exceeded 100, 2 positive peaks of PD merged into M-shaped or mono-peaked PD. Through higher inflow resistance produced by artificial mitral stenosis, PPD peak decayed without NPD. In mitral regurgitation with an acute volume overload, all of the PD amplitudes were exaggerated. Thus the quick reversal of PD suggested the effect in blood filling process across the mitral valve.

Differential pressure pin discharge apparatus

DOEpatents

Oakley, David J.

1987-02-03

Disclosed is a discharge assembly for allowing elongate pins to be discharged from an area of relatively low pressure to an area of relatively greater pressure. The discharge assembly includes a duck valve having a lip piece made of flexible material. The flexible lip piece responds to a fluctuating pressure created downstream by an aspirator. The aspirator reduces the downstream pressure sensed by the duck valve when the discharge assembly is in the open position. This allows elongate pins to be moved through the duck valve with no backflow because the aspirator pressure is less than the pressure in the low pressure area from which the pins originate. Closure of the assembly causes the aspirator static pressure to force the flexible duck valve lip piece into a tightly sealed position also preventing backflow. The discharge assembly can be easily controlled using a single control valve which blocks the flow of aspirator gas and closes the pin passageway extending through the assembly.

Differential pressure pin discharge apparatus

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

Oakley, D.J.

Disclosed is a discharge assembly for allowing elongate pins to be discharged from an area of relatively low pressure to an area of relatively greater pressure. The discharge assembly includes a duck valve having a lip piece made of flexible material. The flexible lip piece responds to a fluctuating pressure created downstream by an aspirator. The aspirator reduces the downstream pressure sensed by the duck valve when the discharge assembly is in the open position. This allows elongate pins to be moved through the duck valve with no backflow because the aspirator pressure is less than the pressure in themore » low pressure area from which the pins originate. Closure of the assembly causes the aspirator static pressure to force the flexible duck valve lip piece into a tightly sealed position also preventing backflow. The discharge assembly can be easily controlled using a single control valve which blocks the flow of aspirator gas and closes the pins passageway extending through the assembly.« less

Differential pressure pin discharge apparatus

DOEpatents

Oakley, D.J.

1984-05-30

Disclosed is a discharge assembly for allowing elongate pins to be discharged from an area of relatively low pressure to an area of relatively greater pressure. The discharge assembly includes a duck valve having a lip piece made of flexible material. The flexible lip piece responds to a fluctuating pressure created downstream by an aspirator. The aspirator reduces the downstream pressure sensed by the duck valve when the discharge assembly is in the open position. This allows elongate pins to be moved through the duck valve with no backflow because the aspirator pressure is less than the pressure in the low pressure area from which the pins originate. Closure of the assembly causes the aspirator static pressure to force the flexible duck valve lip piece into a tightly sealed position also preventing backflow. The discharge assembly can be easily controlled using a single control valve which blocks the flow of aspirator gas and closes the pins passageway extending through the assembly.

Differential pressure pin discharge apparatus

DOEpatents

Oakley, David J.

1987-01-01

Disclosed is a discharge assembly for allowing elongate pins to be discharged from an area of relatively low pressure to an area of relatively greater pressure. The discharge assembly includes a duck valve having a lip piece made of flexible material. The flexible lip piece responds to a fluctuating pressure created downstream by an aspirator. The aspirator reduces the downstream pressure sensed by the duck valve when the discharge assembly is in the open position. This allows elongate pins to be moved through the duck valve with no backflow because the aspirator pressure is less than the pressure in the low pressure area from which the pins originate. Closure of the assembly causes the aspirator static pressure to force the flexible duck valve lip piece into a tightly sealed position also preventing backflow. The discharge assembly can be easily controlled using a single control valve which blocks the flow of aspirator gas and closes the pin passageway extending through the assembly.

Conductance valve and pressure-to-conductance transducer method and apparatus

DOEpatents

Schoeniger, Joseph S.; Cummings, Eric B.; Brennan, James S.

2005-01-18

A device for interrupting or throttling undesired ionic transport through a fluid network is disclosed. The device acts as a fluid valve by reversibly generating a fixed "bubble" in the conducting solvent solution carried by the network. The device comprises a porous hydrophobic structure filling a portion of a connecting channel within the network and optionally incorporates flow restrictor elements at either end of the porous structure that function as pressure isolation barriers, and a fluid reservoir connected to the region of the channel containing the porous structure. Also included is a pressure pump connected to the fluid reservoir. The device operates by causing the pump to vary the hydraulic pressure to a quantity of solvent solution held within the reservoir and porous structure. At high pressures, most or all of the pores of the structure are filled with conducting liquid so the ionic conductance is high. At lower pressures, only a fraction of the pores are filled with liquid, so ionic conductivity is lower. Below a threshold pressure, the porous structure contains only vapor, so there is no liquid conduction path. The device therefore effectively throttles ionic transport through the porous structure and acts as a "conductance valve" or "pressure-to-conductance" transducer within the network.

Remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems.

PubMed

Pan, Tingrui; Baldi, Antonio; Ziaie, Babak

2007-06-01

In this paper, we present two remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems. These valves allow one to vary the opening pressure set-point and flow resistance over a period of time. The first design consists of a micromachined check-valve array using a SU-8 polymer structural layer deposited on the top of a gold sacrificial layer. The second design is based on a variable length cantilever beam structure with a gold sacrificial layer. The adjustable cantilever-beam structure is fabricated by gold thermo-compression bond of a thin silicon wafer over a glass substrate. In both designs, the evaporated gold can be electrochemically dissolved using a constant DC current via a telemetry link. In the first design the dissolution simply opens up individual outlets, while in the second design, gold anchors are sequentially dissolved hence increasing the effective length of the cantilever beam (reducing the opening pressure). A current density of 35 mA/cm(2) is used to dissolve the gold sacrificial layers. Both gravity and syringe-pump driven flow are used to characterize the valve performance. A multi-stage fluidic performance (e.g. flow resistance and opening pressure) is clearly demonstrated.

Multi-bottle, no compressor, mean pressure control system for a Stirling engine

DOEpatents

Corey, John A.

1990-01-01

The invention relates to an apparatus for mean pressure control of a Stirling engine without the need for a compressor. The invention includes a multi-tank system in which there is at least one high pressure level tank and one low pressure level tank wherein gas flows through a maximum pressure and supply line from the engine to the high pressure tank when a first valve is opened until the maximum pressure of the engine drops below that of the high pressure tank opening an inlet regulator to permit gas flow from the engine to the low pressure tank. When gas flows toward the engine it flows through the minimum pressure supply line 2 when a second valve is opened from the low pressure tank until the tank reaches the engine's minimum pressure level at which time the outlet regulator opens permitting gas to be supplied from the high pressure tank to the engine. Check valves between the two tanks prevent any backflow of gas from occurring.

Rapid fabrication of pressure-driven open-channel microfluidic devices in omniphobic R(F) paper.

PubMed

Glavan, Ana C; Martinez, Ramses V; Maxwell, E Jane; Subramaniam, Anand Bala; Nunes, Rui M D; Soh, Siowling; Whitesides, George M

2013-08-07

This paper describes the fabrication of pressure-driven, open-channel microfluidic systems with lateral dimensions of 45-300 microns carved in omniphobic paper using a craft-cutting tool. Vapor phase silanization with a fluorinated alkyltrichlorosilane renders paper omniphobic, but preserves its high gas permeability and mechanical properties. When sealed with tape, the carved channels form conduits capable of guiding liquid transport in the low-Reynolds number regime (i.e. laminar flow). These devices are compatible with complex fluids such as droplets of water in oil. The combination of omniphobic paper and a craft cutter enables the development of new types of valves and switches, such as "fold valves" and "porous switches," which provide new methods to control fluid flow.

Characteristic Analysis and Experiment of a Dynamic Flow Balance Valve

NASA Astrophysics Data System (ADS)

Bin, Li; Song, Guo; Xuyao, Mao; Chao, Wu; Deman, Zhang; Jin, Shang; Yinshui, Liu

2017-12-01

Comprehensive characteristics of a dynamic flow balance valve of water system were analysed. The flow balance valve can change the drag efficient automatically according to the condition of system, and the effective control flowrate is constant in the range of job pressure. The structure of the flow balance valve was introduced, and the theoretical calculation formula for the variable opening of the valve core was derived. A rated pressure of 20kPa to 200kPa and a rated flowrate of 10m3/h were offered in the numerical work. Static and fluent CFX analyses show good behaviours: through the valve core structure optimization and improve design of the compressive spring, the dynamic flow balance valve can stabilize the flowrate of system evidently. And experiments show that the flow control accuracy is within 5%.

Pressure disequilibria induced by rapid valve closure in noble gas extraction lines

USGS Publications Warehouse

Morgan, Leah; Davidheiser-Kroll, Brett

2015-01-01

Pressure disequilibria during rapid valve closures can affect calculated molar quantities for a range of gas abundance measurements (e.g., K-Ar geochronology, (U-Th)/He geochronology, noble gas cosmogenic chronology). Modeling indicates this effect in a system with a 10 L reservoir reaches a bias of 1% before 1000 pipette aliquants have been removed from the system, and a bias of 10% before 10,000 aliquants. Herein we explore the causes and effects of this problem, which is the result of volume changes during valve closure. We also present a solution in the form of an electropneumatic pressure regulator that can precisely control valve motion. This solution reduces the effect to ∼0.3% even after 10,000 aliquants have been removed from a 10 L reservoir.

Pressure disequilibria induced by rapid valve closure in noble gas extraction lines

NASA Astrophysics Data System (ADS)

Morgan, Leah E.; Davidheiser-Kroll, Brett

2015-06-01

Pressure disequilibria during rapid valve closures can affect calculated molar quantities for a range of gas abundance measurements (e.g., K-Ar geochronology, (U-Th)/He geochronology, noble gas cosmogenic chronology). Modeling indicates this effect in a system with a 10 L reservoir reaches a bias of 1% before 1000 pipette aliquants have been removed from the system, and a bias of 10% before 10,000 aliquants. Herein we explore the causes and effects of this problem, which is the result of volume changes during valve closure. We also present a solution in the form of an electropneumatic pressure regulator that can precisely control valve motion. This solution reduces the effect to ˜0.3% even after 10,000 aliquants have been removed from a 10 L reservoir.

Analysis of fatigue reliability for high temperature and high pressure multi-stage decompression control valve

NASA Astrophysics Data System (ADS)

Yu, Long; Xu, Juanjuan; Zhang, Lifang; Xu, Xiaogang

2018-03-01

Based on stress-strength interference theory to establish the reliability mathematical model for high temperature and high pressure multi-stage decompression control valve (HMDCV), and introduced to the temperature correction coefficient for revising material fatigue limit at high temperature. Reliability of key dangerous components and fatigue sensitivity curve of each component are calculated and analyzed by the means, which are analyzed the fatigue life of control valve and combined with reliability theory of control valve model. The impact proportion of each component on the control valve system fatigue failure was obtained. The results is shown that temperature correction factor makes the theoretical calculations of reliability more accurate, prediction life expectancy of main pressure parts accords with the technical requirements, and valve body and the sleeve have obvious influence on control system reliability, the stress concentration in key part of control valve can be reduced in the design process by improving structure.

The Effects of Combined Cyclic Stretch and Pressure on the Aortic Valve Interstitial Cell Phenotype

PubMed Central

Thayer, Patrick; Balachandran, Kartik; Rathan, Swetha; Yap, Choon Hwai; Arjunon, Sivakkumar; Jo, Hanjoong; Yoganathan, Ajit P.

2017-01-01

Aortic valve interstitial cells (VIC) can exhibit phenotypic characteristics of fibroblasts, myofibroblasts, and smooth muscle cells. Others have proposed that valve cells become activated and exhibit myofibroblast or fibroblast characteristics during disease initiation and progression; however, the cues that modulate this phenotypic change remain unclear. We hypothesize that the mechanical forces experienced by the valve play a role in regulating the native phenotype of the valve and that altered mechanical forces result in an activated phenotype. Using a novel ex vivo cyclic stretch and pressure bioreactor, we subjected porcine aortic valve (AV) leaflets to combinations of normal and pathological stretch and pressure magnitudes. The myofibroblast markers α-SMA and Vimentin, along with the smooth muscle markers Calponin and Caldesmon, were analyzed using immunohistochemistry and immunoblotting. Tissue structure was analyzed using Movat’s pentachrome staining. We report that pathological stretch and pressure inhibited the contractile and possibly myofibroblast phenotypes as indicated by downregulation of the proteins α-SMA, Vimentin, and Calponin. In particular, Calponin downregulation implies depolymerization of actin filaments and possible conversion to a more synthetic (non-contractile) phenotype. This agreed well with the increase in spongiosa and fibrosa thickness observed under elevated pressure and stretch that are typically indicative of increased matrix synthesis. Our study therefore demonstrates how cyclic stretch and pressure may possibly act together to modulate the AVIC phenotype. PMID:21347552

Excess flow shutoff valve

DOEpatents

Kiffer, Micah S.; Tentarelli, Stephen Clyde

2016-02-09

Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

Outcomes of Heimlich valve drainage in dogs.

PubMed

Salci, H; Bayram, A S; Gorgul, O S

2009-04-01

Retrospective study of the outcomes of Heimlich valve drainage in dogs. Medical records of the past 3 years were retrospectively reviewed. Heimlich valve drainage was used in 34 dogs (median body weight 30 +/- 5 kg): lobectomy (n = 15), pneumonectomy (n = 9), intrathoracic oesophageal surgery (n = 2), diaphragmatic hernia repair (n = 1), traumatic open pneumothorax (n = 2), bilobectomy (n = 2), ligation of the thoracic duct (n = 1), and chylothorax and pneumothorax (n = 1 each). Evacuation of air and/or fluid from the pleural cavity was performed with the Heimlich valve following thoracostomy tube insertion. During drainage, the dogs were closely monitored for possible respiratory failure. Termination of Heimlich valve drainage was controlled with underwater seal drainage and assessed with thoracic radiography. Negative intrathoracic pressure was provided in 29 dogs without any complications. Post pneumonectomy respiratory syncope and post lobectomy massive hemothorax, which did not originate from the Heimlich valve, were the only postoperative complications. Dysfunction of the valve diaphragm, open pneumothorax and intrathoracic localisation of an acute gastric dilatation-volvulus syndrome caused by a left-sided diaphragmatic hernia following pneumonectomy were the Heimlich valve drainage complications. The Heimlich valve can be used as a continuous drainage device in dogs, but the complications reported here should be considered by veterinary practitioners.

Blood Pressure and Arterial Load After Transcatheter Aortic Valve Replacement for Aortic Stenosis.

PubMed

Lindman, Brian R; Otto, Catherine M; Douglas, Pamela S; Hahn, Rebecca T; Elmariah, Sammy; Weissman, Neil J; Stewart, William J; Ayele, Girma M; Zhang, Feifan; Zajarias, Alan; Maniar, Hersh S; Jilaihawi, Hasan; Blackstone, Eugene; Chinnakondepalli, Khaja M; Tuzcu, E Murat; Leon, Martin B; Pibarot, Philippe

2017-07-01

After aortic valve replacement, left ventricular afterload is often characterized by the residual valve obstruction. Our objective was to determine whether higher systemic arterial afterload-as reflected in blood pressure, pulsatile and resistive load-is associated with adverse clinical outcomes after transcatheter aortic valve replacement (TAVR). Total, pulsatile, and resistive arterial load were measured in 2141 patients with severe aortic stenosis treated with TAVR in the PARTNER I trial (Placement of Aortic Transcatheter Valve) who had systolic blood pressure (SBP) and an echocardiogram obtained 30 days after TAVR. The primary end point was 30-day to 1-year all-cause mortality. Lower SBP at 30 days after TAVR was associated with higher mortality (20.0% for SBP 100-129 mm Hg versus 12.0% for SBP 130-170 mm Hg; P <0.001). This association remained significant after adjustment, was consistent across subgroups, and confirmed in sensitivity analyses. In adjusted models that included SBP, higher total and pulsatile arterial load were associated with increased mortality ( P <0.001 for all), but resistive load was not. Patients with low 30-day SBP and high pulsatile load had a 3-fold higher mortality than those with high 30-day SBP and low pulsatile load (26.1% versus 8.1%; hazard ratio, 3.62; 95% confidence interval, 2.36-5.55). Even after relief of valve obstruction in patients with aortic stenosis, there is an independent association between post-TAVR blood pressure, systemic arterial load, and mortality. Blood pressure goals in patients with a history of aortic stenosis may need to be redefined. Increased pulsatile arterial load, rather than blood pressure, may be a target for adjunctive medical therapy to improve outcomes after TAVR. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00530894. © 2017 American Heart Association, Inc.

An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

NASA Astrophysics Data System (ADS)

Jung, Wooseok; Barrett, Matthew; Brooks, Carla; Rivera, Andrew; Birdsell, Dawn N.; Wagner, David M.; Zenhausern, Frederic

2015-12-01

We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30-100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis.

Development of Overflow-Prevention Valve with Trigger Mechanism.

NASA Astrophysics Data System (ADS)

Ishino, Yuji; Mizuno, Takeshi; Takasaki, Masaya

2016-09-01

A new overflow-prevention valve for combustible fluid is developed which uses a trigger mechanism. Loading arms for combustible fluid are used for transferring oil from a tanker to tanks and vice versa. The loading arm has a valve for preventing overflow. Overflow- prevention valves cannot use any electric component to avoid combustion. Therefore, the valve must be constructed only by mechanical parts. The conventional overflow-prevention valve uses fluid and pneumatic forces. It consists of a sensor probe, a cylinder, a main valve for shutting off the fluid and a locking mechanism for holding an open state of the main valve. The proposed overflow-prevention valve uses the pressure due to the height difference between the fluid level of the tank and the sensor probe. However, the force of the cylinder produced by the pressure is too small to release the locking mechanism. Therefore, a trigger mechanism is introduced between the cylinder and the locking mechanism. The trigger mechanism produces sufficient force to release the locking mechanism and close the main valve when the height of fluid exceeds a threshold value. A trigger mechanism is designed and fabricated. The operation necessary for closing the main valve is conformed experimentally.

74. LIQUID NITROGEN TANK, REGULATOR VALVES, AND PRESSURE GAUGES FOR ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

74. LIQUID NITROGEN TANK, REGULATOR VALVES, AND PRESSURE GAUGES FOR LIQUID NITROGEN PUMPING STATION - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

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.

Optimal Control of the Valve Based on Traveling Wave Method in the Water Hammer Process

NASA Astrophysics Data System (ADS)

Cao, H. Z.; Wang, F.; Feng, J. L.; Tan, H. P.

2011-09-01

Valve regulation is an effective method for process control during the water hammer. The principle of d'Alembert traveling wave theory was used in this paper to construct the exact analytical solution of the water hammer, and the optimal speed law of the valve that can reduce the water hammer pressure in the maximum extent was obtained. Combining this law with the valve characteristic curve, the principle corresponding to the valve opening changing with time was obtained, which can be used to guide the process of valve closing and to reduce the water hammer pressure in the maximum extent.

System for pressure letdown of abrasive slurries

DOEpatents

Kasper, Stanley

1991-01-01

A system and method for releasing erosive slurries from containment at high pressure without subjecting valves to highly erosive slurry flow. The system includes a pressure letdown tank disposed below the high-pressure tank, the two tanks being connected by a valved line communicating the gas phases and a line having a valve and choke for a transfer of liquid into the letdown tank. The letdown tank has a valved gas vent and a valved outlet line for release of liquid. In operation, the gas transfer line is opened to equalize pressure between tanks so that a low level of liquid flow occurs. The letdown tank is then vented, creating a high-pressure differential between the tanks. At this point, flow between tanks is controlled by the choke. High-velocity, erosive flow through a high-pressure outlet valve is prevented by equalizing the start up pressure and thereafter limiting flow with the choke.

Curved butterfly bileaflet prosthetic cardiac valve

DOEpatents

McQueen, David M.; Peskin, Charles S.

1991-06-25

An annular valve body having a central passageway for the flow of blood therethrough with two curved leaflets each of which is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance.

Polymeric check valve with an elevated pedestal for precise cracking pressure in a glaucoma drainage device.

PubMed

Park, Chang-Ju; Yang, Dong-Seong; Cha, Jung-Joon; Lee, Jong-Hyun

2016-02-01

This paper presents the design, fabrication, and characterization of a polymeric micro check valve for a glaucoma drainage device (GDD) featuring the precise regulation of intraocular pressure (IOP) and effective aqueous humor turnover (AHT). The pedestal, slightly elevated by selective coating of a parylene C film, induces pre-stress in the thin valve membrane, which enhances the predictability of the cracking pressure of the GDD. The proposed GDD comprises a cannula and a normally closed polymeric micro check valve, which are made of PDMS, a biocompatible polymer, with three layers: top (cover), intermediate (thin valve membrane), and bottom (base plate). A feedback channel, located between the top and intermediate layers, prevents reverse flow by feeding the pressure of the outlet channel back to the thin valve membrane. To achieve a precise cracking pressure and sufficient drainage of humor for humans, the thicknesses of the valve membrane and parylene C film are designed to be 58 μm and 1 μm, respectively, which are confirmed using a COMSOL simulation. The experimental results show that the cracking pressure of the fabricated GDD lies within the range of normal IOP (1.33-2.67 kPa). The forward flow rate (drainage rate), 4.3 ± 0.9 μL/min at 2.5 kPa, is adequate to accommodate the rate of AHT in a normal human eye (2.4 ± 0.6 μL/min). The reverse flow was not observed when a hydrostatic pressure of up to 4 kPa was applied to the outlet and the feedback channel.

Pediatric Tubular Pulmonary Heart Valve from Decellularized Engineered Tissue Tubes

PubMed Central

Reimer, Jay M.; Syedain, Zeeshan H.; Haynie, Bee H.T.; Tranquillo, Robert T.

2015-01-01

Pediatric patients account for a small portion of the heart valve replacements performed, but a pediatric pulmonary valve replacement with growth potential remains an unmet clinical need. Herein we report the first tubular heart valve made from two decellularized, engineered tissue tubes attached with absorbable sutures, which can meet this need, in principle. Engineered tissue tubes were fabricated by allowing ovine dermal fibroblasts to replace a sacrificial fibrin gel with an aligned, cell-produced collagenous matrix, which was subsequently decellularized. Previously, these engineered tubes became extensively recellularized following implantation into the sheep femoral artery. Thus, a tubular valve made from these tubes may be amenable to recellularization and, ideally, somatic growth. The suture line pattern generated three equi-spaced “leaflets” in the inner tube, which collapsed inward when exposed to back pressure, per tubular valve design. Valve testing was performed in a pulse duplicator system equipped with a secondary flow loop to allow for root distention. All tissue-engineered valves exhibited full leaflet opening and closing, minimal regurgitation (< 5%), and low systolic pressure gradients (< 2.5 mmHg) under pulmonary conditions. Valve performance was maintained under various trans-root pressure gradients and no tissue damage was evident after 2 million cycles of fatigue testing. PMID:26036175

Rotary sequencing valve with flexible port plate

DOEpatents

Wagner, Glenn Paul

2005-05-10

Rotary sequencing valve comprising a rotor having a rotor face rotatable about an axis perpendicular to the rotor face, wherein the rotor face has a plurality of openings, one or more of which are disposed at a selected radial distance from the axis, and wherein the rotor includes at least one passage connecting at least one pair of the plurality of openings. The valve includes a flexible port plate having a first side and a second side, wherein the first side faces the rotor and engages the rotor such that the flexible port plate can be rotated coaxially by the rotor and can move axially with respect to the rotor, wherein the flexible port plate has a plurality of ports between the first and second sides, which ports are aligned with the openings in the rotor face. The valve also includes a stator having a stator face disposed coaxially with the rotor and the flexible port plate, wherein the second side of the flexible port plate is in sealable, slidable rotary contact with the stator face, wherein the stator face has a plurality of openings, some of which are disposed at the selected radial distance from the axis, and wherein the plurality of openings extend as passages through the stator. The valve may be used in pressure or temperature swing adsorption systems.

Electromechanically Actuated Valve for Controlling Flow Rate

NASA Technical Reports Server (NTRS)

Patterson, Paul

2007-01-01

. The inlet end (the right end as depicted in the figure) of the ball screw would be the main seating valve element: in the fully closed position, it would be pressed against the valve seat, as depicted in the upper part of the figure. A retainer would hold the valve seat in an inlet fitting. In addition, the retainer would be contoured to obtain a specified flow rate as a function of axial position of the ball screw. In the fully closed position, little force would be needed to press the ball screw against the seat because the push bore area upon which the upstream pressure would act would be small. The motor would position and hold the ball screw against the seat, providing the force necessary for sealing. To open the valve to a particular position, the motor would be commanded to rotate to a particular angular position (equivalently, a particular number of revolutions) at a particular rate of rotation within its torque limitations. Once the valve was open, fluid would flow through the inlet fitting and the chamber in the inlet housing, past the seat and its retainer, along the hollow core of the ball screw, and through the outlet housing and outlet fitting. The net force generated from fluid pressure in the open position would be small because the pressure exposed to the push bore areas at the inlet and outlet are nearly equal and the forces generated would be in opposing directions.

Study on the characters of control valve for ammonia injection in selective catalytic reduction (SCR) system of coal-fired power plant

NASA Astrophysics Data System (ADS)

Yao, Che; Li, Tao; Zhang, Hong; Zhou, Yanming

2017-08-01

In this paper, the characters of two control valves used for ammonia injection in SCR system are discussed. The linear/quadratic character between pressure drop/outlet flow rate and valve opening/dynamic pressure inlet are investigated using computational fluid dynamic (CFD) and response surface analysis (RSA) methods. The results show that the linear character of brake valve is significantly better than butterfly valve, which means that the brake valve is more suitable for ammonia injection adjustment than the butterfly valve.

TUBE SHEARING VALVE

DOEpatents

Wilner, L.B.

1960-05-24

Explosive operated valves can be used to join two or more containers in fluid flow relationship, one such container being a sealed reservoir. The valve is most simply disposed by mounting it on the reservoir so thst a tube extends from the interior of the reservoir through the valve body, terminating at the bottom of the bore in a closed end; other containers may be similarly connected or may be open connected, as desired. The piston of the valve has a cutting edge at its lower end which shears off the closed tube ends and a recess above the cutting edge to provide a flow channel. Intermixing of the fluid being transferred with the explosion gases is prevented by a copper ring at the top of the piston which is force fitted into the bore at the beginning of the stroke. Although designed to avoid backing up of the piston at pressures up to 10,000 psi in the transferred fluid, proper operation is independent of piston position, once the tube ends were sheared.

5. AERATOR VIEW FROM DOWNSTREAM. FLUSH VALVE AT RIGHT OPENS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. AERATOR VIEW FROM DOWNSTREAM. FLUSH VALVE AT RIGHT OPENS TO CLEAR THE SYSTEM ABOVE THE SILT AND DEBRIS AND TO STOP THE FLOW OF WATER INTO THE SYSTEM DOWN LINE. BOX FLUME CONTINUES DOWN LINE TO SEDIMENTATION CHAMBER. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

Face-Sealing Butterfly Valve

NASA Technical Reports Server (NTRS)

Tervo, John N.

1992-01-01

Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

Continuous-flow cardiac assistance: effects on aortic valve function in a mock loop.

PubMed

Tuzun, Egemen; Rutten, Marcel; Dat, Marco; van de Vosse, Frans; Kadipasaoglu, Cihan; de Mol, Bas

2011-12-01

As the use of left ventricular assist devices (LVADs) to treat end-stage heart failure has become more widespread, leaflet fusion--with resul-tant aortic regurgitation--has been observed more frequently. To quantitatively assess the effects of nonpulsatile flow on aortic valve function, we tested a continuous-flow LVAD in a mock circulatory system (MCS) with an interposed valve. To mimic the hemodynamic characteristics of LVAD patients, we utilized an MCS in which a Jarvik 2000 LVAD was positioned at the base of a servomotor-operated piston pump (left ventricular chamber). We operated the LVAD at 8000 to 12,000 rpm, changing the speed in 1000-rpm increments. At each speed, we first varied the outflow resistance at a constant stroke volume, then varied the stroke volume at a constant outflow resistance. We measured the left ventricular pressure, aortic pressure, pump flow, and total flow, and used these values to compute the change, if any, in the aortic duty cycle (aortic valve open time) and transvalvular aortic pressure loads. Validation of the MCS was demonstrated by the simulation of physiologic pressure and flow waveforms. At increasing LVAD speeds, the mean aortic pressure load steadily increased, while the aortic duty cycle steadily decreased. Changes were consistent for each MCS experimental setting, despite variations in stroke volume and outflow resistance. Increased LVAD flow results in an impaired aortic valve-open time due to a pressure overload above the aortic valve. Such an overload may initiate structural changes, causing aortic leaflet fusion and/or regurgitation. Copyright © 2011 Elsevier Inc. All rights reserved.

Importance of pressure reducing valves (PRVs) in water supply networks.

NASA Astrophysics Data System (ADS)

Signoreti, R. O. S.; Camargo, R. Z.; Canno, L. M.; Pires, M. S. G.; Ribeiro, L. C. L. J.

2016-08-01

Challenged with the high rate of leakage from water supply systems, these managers are committed to identify control mechanisms. In order to standardize and control the pressure Pressure Reducing Valves (VRP) are installed in the supply network, shown to be more effective and provide a faster return for the actual loss control measures. It is known that the control pressure is while controlling the occurrence of leakage. Usually the network is sectored in areas defined by pressure levels according to its topography, once inserted the VRP in the same system will limit the downstream pressure. This work aims to show the importance of VRP as loss reduction for tool.

Intracranial Pressure-Guided Shunt Valve Adjustments with the Miethke Sensor Reservoir.

PubMed

Antes, Sebastian; Stadie, Axel; Müller, Simon; Linsler, Stefan; Breuskin, David; Oertel, Joachim

2018-01-01

Telemetric intracranial pressure (ICP) monitoring seems to be a promising therapy-supporting option in shunt-treated patients. Benefits become obvious when headaches are unspecific and clinical symptoms cannot be related to possible overdrainage or underdrainage. In this study, we evaluated a new telemetric device to individually adjust shunt valves according to ICP measurements. Between December 2015 and November 2016, 25 patients with suspected suboptimal shunt valve settings underwent insertion of a telemetric ICP sensor (Sensor Reservoir; Christoph Miethke, Potsdam, Germany). Over a 1-year period, a total of 183 telemetric ICP measurements and 85 shunt valve adjustments were carried out. Retrospective statistic analyses focused on valve adjustments, ICP values, and clinical outcomes. ICP-guided valve adjustments positively changed the clinical state in 18 out of 25 patients. Clinical improvement over time was associated with significant changes of the valve settings and ICP values. Interestingly, a therapeutically normalized ICP profile was not automatically associated with clinical improvement. The Sensor Reservoir is an important and valuable tool for shunt-treated patients suffering from drainage-related problems. The possibility to simultaneously recognize and solve shunt problems represents the decisive advantage. Nevertheless, measurements with the Sensor Reservoir did not allow for the determination of default valve settings or universal target ICP values. Copyright © 2017 Elsevier Inc. All rights reserved.

Frostless heat pump having thermal expansion valves

DOEpatents

Chen, Fang C [Knoxville, TN; Mei, Viung C [Oak Ridge, TN

2002-10-22

A heat pump system having an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant and further having a compressor, an interior heat exchanger, an exterior heat exchanger, a heat pump reversing valve, an accumulator, a thermal expansion valve having a remote sensing bulb disposed in heat transferable contact with the refrigerant piping section between said accumulator and said reversing valve, an outdoor temperature sensor, and a first means for heating said remote sensing bulb in response to said outdoor temperature sensor thereby opening said thermal expansion valve to raise suction pressure in order to mitigate defrosting of said exterior heat exchanger wherein said heat pump continues to operate in a heating mode.

Quickly Removable Valve

NASA Technical Reports Server (NTRS)

Robbins, John S.

1988-01-01

Unit removed with minimal disturbance. Valve inlet and outlet ports adjacent to each other on same side of valve body. Ports inserted into special manifold on fluid line. Valve body attached to manifold by four bolts or, alternatively, by toggle clamps. Electromechanical actuator moves in direction parallel to fluid line to open and close valve. When necessary to clean valve, removed simply by opening bolts or toggle clamps. No need to move or separate ports of fluid line. Valve useful where disturbance of fluid line detrimental or where fast maintenance essential - in oil and chemical industries, automotive vehicles, aircraft, and powerplants.

Design and Development of Sequential Rotary Valve

NASA Technical Reports Server (NTRS)

D’Orsi, Nicholas; Castillo, Priscilla

2017-01-01

Valves are used to regulate the flow of fluids through systems. This rotary valve's main purpose is to fill, pressurize, empty, and vent three smaller tanks with the supply of one larger tank. Many different designs are being taken into consideration, which are each at different stages of development. The furthest along uses three ball valves on a common shaft to open and close their respective ports as the shaft completes one full rotation or cycle. We were tasked with advancing this design to its first test as a plastic model for flow verification, as well as sizing and ordering the necessary O-rings and fasteners. A motor will also be sized to satisfy the torque requirements, and will then be programmed using a Raspberry Pi to rotate the shaft at the calculated speed and dwelling times needed to fill each tank equally. In addition, we have also been advancing designs that use a camshaft and poppets. These are earlier on in their development, currently being sized to replicate the expected flow patterns of the rotary ball valve. Expected outcomes of this valve include bi-directionality, successful sealing under pressure, and accurate cycling.

40 CFR 265.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2011 CFR

2011-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief...

40 CFR 265.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2012 CFR

2012-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief...

40 CFR 265.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2013 CFR

2013-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief...

40 CFR 265.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2014 CFR

2014-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief...

Solenoid Driven Pressure Valve System: Toward Versatile Fluidic Control in Paper Microfluidics.

PubMed

Kim, Taehoon H; Hahn, Young Ki; Lee, Jungmin; van Noort, Danny; Kim, Minseok S

2018-02-20

As paper-based diagnostics has become predominantly driven by more advanced microfluidic technology, many of the research efforts are still focused on developing reliable and versatile fluidic control devices, apart from improving sensitivity and reproducibility. In this work, we introduce a novel and robust paper fluidic control system enabling versatile fluidic control. The system comprises a linear push-pull solenoid and an Arduino Uno microcontroller. The precisely controlled pressure exerted on the paper stops the flow. We first determined the stroke distance of the solenoid to obtain a constant pressure while examining the fluidic time delay as a function of the pressure. Results showed that strips of grade 1 chromatography paper had superior reproducibility in fluid transport. Next, we characterized the reproducibility of the fluidic velocity which depends on the type and grade of paper used. As such, we were able to control the flow velocity on the paper and also achieve a complete stop of flow with a pressure over 2.0 MPa. Notably, after the actuation of the pressure driven valve (PDV), the previously pressed area regained its original flow properties. This means that, even on a previously pressed area, multiple valve operations can be successfully conducted. To the best of our knowledge, this is the first demonstration of an active and repetitive valve operation in paper microfluidics. As a proof of concept, we have chosen to perform a multistep detection system in the form of an enzyme-linked immunosorbent assay with mouse IgG as the target analyte.

Fast-Acting Valve

NASA Technical Reports Server (NTRS)

Wojciechowski, Bogdan V. (Inventor); Pegg, Robert J. (Inventor)

2003-01-01

A fast-acting valve includes an annular valve seat that defines an annular valve orifice between the edges of the annular valve seat, an annular valve plug sized to cover the valve orifice when the valve is closed, and a valve-plug holder for moving the annular valve plug on and off the annular valve seat. The use of an annular orifice reduces the characteristic distance between the edges of the valve seat. Rather than this distance being equal to the diameter of the orifice, as it is for a conventional circular orifice, the characteristic distance equals the distance between the inner and outer radii (for a circular annulus). The reduced characteristic distance greatly reduces the gap required between the annular valve plug and the annular valve seat for the valve to be fully open, thereby greatly reducing the required stroke and corresponding speed and acceleration of the annular valve plug. The use of a valve-plug holder that is under independent control to move the annular valve plug between its open and closed positions is important for achieving controllable fast operation of the valve.

Effect of transcatheter aortic valve implantation on intraoperative left ventricular end-diastolic pressure.

PubMed

Toyota, Kosaku; Ota, Takashi; Nagamine, Katsutoshi; Koide, Yasuhiro; Nomura, Takeshi; Yamanaka, Futoshi; Shishido, Koki; Tanaka, Masashi; Saito, Shigeru

2016-12-01

Transcatheter aortic valve implantation (TAVI) for patients with aortic stenosis is a less invasive alternative to surgical aortic valve replacement. Despite this, careful anesthetic management, especially strict control of blood pressure and fluid management, is necessary. During TAVI, normalization of left ventricular afterload due to aortic balloon valvuloplasty and prosthetic valve deployment is expected to result in rapid improvement of systolic function and consequent improvement in diastolic function. However, the early effect of TAVI on left ventricular diastolic function is less clear. We hypothesized that TAVI induces a rapid decrease in left ventricular end-diastolic pressure (LVEDP) after valve deployment. This retrospective observational study included 71 patients who had undergone TAVI using the transfemoral approach with a balloon-expandable valve under general anesthesia. Intraoperative LVEDP was measured using an intracardiac catheter. The severity of residual aortic regurgitation (AR) was assessed using the Sellers criteria. The mean (SD) LVEDP was 17.8 (5.3) mmHg just before TAVI and increased significantly to 27.3 (8.2) mmHg immediately after prosthetic valve deployment (p < 0.0001). The change in LVEDP was 8.7 (8.6) mmHg in patients with low residual AR (Sellers ≤1) and 11.0 (7.1) mmHg in those with high residual AR (Sellers ≥2); however, this difference was not significant. No correlation was found between the LVEDP change and intraoperative fluid balance. In conclusion, LVEDP increased significantly in the early period after valve deployment during TAVI, regardless of residual AR severity. It was suggested that the tolerability of fluid load could be reduced at that time.

A normally-closed piezoelectric micro-valve with flexible stopper

NASA Astrophysics Data System (ADS)

Chen, Song; Lu, Song; Liu, Yong; Wang, Jiantao; Tian, Xiaochao; Liu, Guojun; Yang, Zhigang

2016-04-01

In the field of controlled drug delivery system, there are still many problems on those reported micro-valves, such as the small opening height, unsatisfactory particle tolerance and high cost. To solve the above problems, a novel normally-closed piezoelectric micro-valve is presented in this paper. The micro-valve was driven by circular unimorph piezoelectric vibrator and natural rubber membrane with high elasticity was used as the valve stopper. The small axial displacement of piezoelectric vibrator can be converted into a large stroke of valve stopper based on hydraulic amplification mechanism. The experiment indicates that maximum hydraulic amplification ratio is up to 14, and the cut-off pressure of the micro-valve is 39kPa in the case of no working voltage. The presented micro valve has a large flow control range (ranging from 0 to 8.75mL/min).

Durability Tests of Ball Valve Prototype with Flowmeter Operation

NASA Astrophysics Data System (ADS)

Rogula, J.; Romanik, G.

2018-02-01

The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program "Intelligent Development" (POIR 01.01.01-00-0013 / 15 "Development of devices for measurement of media flow on industrial trunk-lines".

31. DETAIL OF PRESSURE GAUGE AND ASSOCIATED VALVES AND TUBING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

31. DETAIL OF PRESSURE GAUGE AND ASSOCIATED VALVES AND TUBING FOR STRETCH SLING CYLINDER. GAUGE LOCATED IN SOUTHWEST CORNER OF SLC-3W MST STATION 78. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

Microspheres as resistive elements in a check valve for low pressure and low flow rate conditions.

PubMed

Ou, Kevin; Jackson, John; Burt, Helen; Chiao, Mu

2012-11-07

In this paper we describe a microsphere-based check valve integrated with a micropump. The check valve uses Ø20 μm polystyrene microspheres to rectify flow in low pressure and low flow rate applications (Re < 1). The microspheres form a porous medium in the check valve increasing fluidic resistance based on the direction of flow. Three check valve designs were fabricated and characterized to study the microspheres' effectiveness as resistive elements. A maximum diodicity (ratio of flow in the forward and reverse direction) of 18 was achieved. The pumping system can deliver a minimum flow volume of 0.25 μL and a maximum flow volume of 1.26 μL under an applied pressure of 0.2 kPa and 1 kPa, respectively. A proof-of-concept study was conducted using a pharmaceutical agent, docetaxel (DTX), as a sample drug showing the microsphere check valve's ability to limit diffusion from the micropump. The proposed check valve and pumping concept shows strong potential for implantable drug delivery applications with low flow rate requirements.

A study of waste and delivery valve design modification to the pump performance

NASA Astrophysics Data System (ADS)

Harith, M. N.; Bakar, R. A.; Ramasamy, D.; Kardigama, K.; Quanjin, Ma

2018-04-01

This paper objective is to share design revolution of waste and delivery valve that contribute to the overall pump performance. In this paper, 3 new designs of waste and delivery valve pump are presented with comprehensive internal flow analysis using computational fluid dynamics (CFD) simulation over 4 cases that have been deeply study for one of the design chosen. 4 cases involving opening and closing both valve or either one. 0.265m height size of customized waste valve with an opening limiter and spring was used to demonstrate cyclic closing and opening valve operation extended up to 0.164m gap. Based on result, this characteristics contribute to 10-20% waste water reduction and enhancement of flow rate height up to 80m. Apart from that this paper also share some of pressure (dynamic, total, static), velocity (x, y, z axis) simulation including the vector flow were under different flow cases.

Dynamic modeling and simulation of an integral bipropellant propulsion double-valve combined test system

NASA Astrophysics Data System (ADS)

Chen, Yang; Wang, Huasheng; Xia, Jixia; Cai, Guobiao; Zhang, Zhenpeng

2017-04-01

For the pressure reducing regulator and check valve double-valve combined test system in an integral bipropellant propulsion system, a system model is established with modular models of various typical components. The simulation research is conducted on the whole working process of an experiment of 9 MPa working condition from startup to rated working condition and finally to shutdown. Comparison of simulation results with test data shows: five working conditions including standby, startup, rated pressurization, shutdown and halt and nine stages of the combined test system are comprehensively disclosed; valve-spool opening and closing details of the regulator and two check valves are accurately revealed; the simulation also clarifies two phenomena which test data are unable to clarify, one is the critical opening state in which the check valve spools slightly open and close alternately in their own fully closed positions, the other is the obvious effects of flow-field temperature drop and temperature rise in pipeline network with helium gas flowing. Moreover, simulation results with consideration of component wall heat transfer are closer to the test data than those under the adiabatic-wall condition, and more able to reveal the dynamic characteristics of the system in various working stages.

Valve

DOEpatents

Cho, Nakwon

1980-01-01

A positive acting valve suitable for operation in a corrosive environment is provided. The valve includes a hollow valve body defining an open-ended bore for receiving two, axially aligned, spaced-apart, cylindrical inserts. One insert, designated the seat insert, terminates inside the valve body in an annular face which lies within plane normal to the axis of the two inserts. An elastomeric O-ring seal is disposed in a groove extending about the annular face. The other insert, designated the wedge insert, terminates inside the valve body in at least two surfaces oppositely inclined with respect to each other and with respect to a plane normal to the axis of the two inserts. An elongated reciprocable gate, movable between the two inserts along a path normal to the axis of the two inserts, has a first flat face portion disposed adjacent and parallel to the annular face of the seat insert. The gate has a second face portion opposite to the first face portion provided with at least two oppositely inclined surfaces for mating with respective inclined surfaces of the wedge insert. An opening is provided through the gate which registers with a flow passage through the two inserts when the valve is open. Interaction of the respective inclined surfaces of the gate and wedge insert act to force the first flat face portion of the gate against the O-ring seal in the seat insert at the limits of gate displacement where it reaches its respective fully open and fully closed positions.

Shape Memory Actuated Normally Open Permanent Isolation Valve

NASA Technical Reports Server (NTRS)

Ramspacher, Daniel J. (Inventor); Bacha, Caitlin E. (Inventor)

2017-01-01

A valve assembly for an in-space propulsion system includes an inlet tube, an outlet tube, a valve body coupling the inlet tube to the outlet tube and defining a propellant flow path, a valve stem assembly disposed within the valve body, an actuator body coupled to the valve body, the valve stem assembly extending from an interior of the valve body to an interior of the actuator body, and an actuator assembly disposed within the actuator body and coupled to the valve stem assembly, the actuator assembly including a shape memory actuator member that when heated to a transition temperature is configured to enable the valve stem assembly to engage the outlet tube and seal the propellant flow path.

Shuttle Primary Reaction Control Subsystem Thruster Fuel Valve Pilot Seal Extrusion: A Failure Correlation

NASA Technical Reports Server (NTRS)

Waller, Jess; Saulsberry, Regor L.

2003-01-01

Pilot operated valves (POVs) are used to control the flow of hypergolic propellants monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer) to the Shuttle orbiter Primary Reaction Control Subsystem (PRCS) thrusters. The POV incorporates a two-stage design: a solenoid-actuated pilot stage, which in turn controls a pressure-actuated main stage. Isolation of propellant supply from the thruster chamber is accomplished in part by a captive polytetrafluoroethylene (PTFE) pilot seal retained inside a Custom 455.1 stainless steel cavity. Extrusion of the pilot seal restricts the flow of fuel around the pilot poppet, thus impeding or preventing the main valve stage from opening. It can also prevent the main stage from staying open with adequate force margin, particularly if there is gas in the main stage actuation cavity. During thruster operation on-orbit, fuel valve pilot seal extrusion is commonly indicated by low or erratic chamber pressure or failure of the thruster to fire upon command (Fail-Off). During ground turnaround, pilot seal extrusion is commonly indicated by slow gaseous nitrogen (GN2) main valve opening times (greater than 38 ms) or slow water main valve opening response times (greater than 33 ms). Poppet lift tests and visual inspection can also detect pilot seal extrusion during ground servicing; however, direct metrology on the pilot seat assembly provides the most quantitative and accurate means of identifying extrusion. Minimizing PRCS fuel valve pilot seal extrusion has become an important issue in the effort to improve PRCS reliability and reduce associated life cycle costs.

Miniaturised electrically actuated high pressure injection valve for portable capillary liquid chromatography.

PubMed

Li, Yan; Pace, Kirsten; Nesterenko, Pavel N; Paull, Brett; Stanley, Roger; Macka, Mirek

2018-04-01

A miniaturised high pressure 6-port injection valve has been designed and evaluated for its performance in order to facilitate the development of portable capillary high performance liquid chromatography (HPLC). The electrically actuated valve features a very small size (65 × 19 × 19mm) and light weight (33g), and therefore can be easily integrated in a miniaturised modular capillary LC system suited for portable field analysis. The internal volume of the injection valve was determined as 98 nL. The novel conical shape of the stator and rotor and the spring-loaded rotor performed well up to 32MPa (4641psi), the maximum operating pressure investigated. Suitability for application was demonstrated using a miniaturised capillary LC system applied to the chromatographic separation of a mixture of biogenic amines and common cations. The RSD (relative standard deviation) values of retention times and peak areas of 6 successive runs were 0.5-0.7% and 1.8-2.8% for the separation of biogenic amines, respectively, and 0.1-0.2% and 2.1-3.0% for the separation of cations, respectively. This performance was comparable with bench-top HPLC systems thus demonstrating the applicability of the valve for use in portable and miniaturised capillary HPLC systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Bidirectional piston valve

DOEpatents

Fischer, Harry C.

1977-01-01

This invention is a reversing valve having an inlet, an outlet, and an inlet-outlet port. The valve is designed to respond to the introduction of relatively high-pressure fluid at its inlet or, alternatively, of lower-pressure fluid at its inlet-outlet port. The valve includes an axially slidable assembly which is spring-biased to a position where it isolates the inlet and connects the inlet-outlet port to the outlet. The admission of high-pressure fluid to the inlet displaces the slidable assembly to a position where the outlet is isolated and the inlet is connected to the inlet-outlet port. The valve is designed to minimize pressure drops and leakage. It is of a reliable and comparatively simple design.

Optimization of the freeze-drying cycle: adaptation of the pressure rise analysis model to non-instantaneous isolation valves.

PubMed

Chouvenc, P; Vessot, S; Andrieu, J; Vacus, P

2005-01-01

The principal aim of this study is to extend to a pilot freeze-dryer equipped with a non-instantaneous isolation valve the previously presented pressure rise analysis (PRA) model for monitoring the product temperature and the resistance to mass transfer of the dried layer during primary drying. This method, derived from the original MTM method previously published, consists of interrupting rapidly (a few seconds) the water vapour flow from the sublimation chamber to the condenser and analysing the resulting dynamics of the total chamber pressure increase. The valve effect on the pressure rise profile observed during the isolation valve closing period was corrected by introducing in the initial PRA model a valve characteristic function factor which turned out to be independent of the operating conditions. This new extended PRA model was validated by implementing successively the two types of valves and by analysing the pressure rise kinetics data with the corresponding PRA models in the same operating conditions. The coherence and consistency shown on the identified parameter values (sublimation front temperature, dried layer mass transfer resistance) allowed validation of this extended PRA model with a non-instantaneous isolation valve. These results confirm that the PRA method, with or without an instantaneous isolation valve, is appropriate for on-line monitoring of product characteristics during freeze-drying. The advantages of PRA are that the method is rapid, non-invasive, and global. Consequently, PRA might become a powerful and promising tool not only for the control of pilot freeze-dryers but also for industrial freeze-dryers equipped with external condensers.

49 CFR Appendix A to Part 180 - Internal Self-closing Stop Valve Emergency Closure Test for Liquefied Compressed Gases

Code of Federal Regulations, 2010 CFR

2010-10-01

... Test for Liquefied Compressed Gases A Appendix A to Part 180 Transportation Other Regulations Relating... Compressed Gases 1. In performing this test, all internal self-closing stop valves must be opened. Each.... 2. On pump-actuated pressure differential internal valves, the three-way toggle valve handle or its...

Drive piston assembly for a valve actuator assembly

DOEpatents

Sun, Zongxuan

2010-02-23

A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

The optimization of design parameters for surge relief valve for pipeline systems

NASA Astrophysics Data System (ADS)

Kim, Hyunjun; Hur, Jisung; Kim, Sanghyun

2017-06-01

Surge is an abnormal pressure which induced by rapid changes of flow rate in pipeline systems. In order to protect pipeline system from the surge pressure, various hydraulic devices have been developed. Surge-relief valve(SRV) is one of the widely applied devices to control surge due to its feasibility in application, efficiency and cost-effectiveness. SRV is designed to automatically open under abnormal pressure and discharge the flow and makes pressure of the system drop to the allowable level. The performance of the SRV is influenced by hydraulics. According to previous studies, there are several affecting factors which determine performance of the PRV such as design parameters (e.g. size of the valve), system parameters (e.g. number of the valves and location of the valve), and operation parameters (e.g. set point and operation time). Therefore, the systematic consideration for factors affecting performance of SRV is required for the proper installation of SRV in the system. In this study, methodology for finding optimum parameters of the SRV is explored through the integration of Genetic Algorithm(GA) into surge analysis.

40 CFR 60.482-8 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2014 CFR

2014-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and connectors. 60.482-8... Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid... any other detection method at pumps and valves in heavy liquid service, pressure relief devices in...

40 CFR 60.482-8 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2013 CFR

2013-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and connectors. 60.482-8... Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid... any other detection method at pumps and valves in heavy liquid service, pressure relief devices in...

40 CFR 60.482-8 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2012 CFR

2012-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and connectors. 60.482-8... Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid... any other detection method at pumps and valves in heavy liquid service, pressure relief devices in...

40 CFR 60.482-8 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2011 CFR

2011-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and connectors. 60.482-8... Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid... any other detection method at pumps and valves in heavy liquid service, pressure relief devices in...

Long life valve design concepts

NASA Technical Reports Server (NTRS)

Jones, J. R.; Hall, A. H., Jr.

1975-01-01

Valve concept evaluation, final candidate selection, design, manufacture, and demonstration testing of a pneumatically actuated 10-inch hybrid poppet butterfly shutoff valve are presented. Conclusions and recommendations regarding those valve characteristics and features which would serve to guide in the formulation of future valve procurements are discussed. The pertinent design goals were temperature range of plus 200 to minus 423 F, valve inlet pressure 35 psia, actuation pressure 750 psia, main seal leakage 3 x 0.00001 sccs at 35 psia valve inlet pressure, and a storage and operating life of 10 years. The valve was designed to be compatible with RP-1, propane, LH2, LO2, He, and N2.

Space Vehicle Valve System

NASA Technical Reports Server (NTRS)

Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

2014-01-01

The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

Transcatheter aortic valve implantation in patients with bicuspid aortic valve stenosis.

PubMed

Wijesinghe, Namal; Ye, Jian; Rodés-Cabau, Josep; Cheung, Anson; Velianou, James L; Natarajan, Madhu K; Dumont, Eric; Nietlispach, Fabian; Gurvitch, Ronen; Wood, David A; Tay, Edgar; Webb, John G

2010-11-01

We evaluated transcatheter aortic valve implantation (TAVI) in high-risk patients with bicuspid aortic valve (BAV) stenosis. TAVI shows promise in the treatment of severe stenosis of triscupid aortic valves, especially in high-risk patients. However, BAV stenosis has been considered a contraindication to TAVI. Eleven patients (age 52 to 90 years) with symptomatic severe BAV stenosis underwent TAVI at 3 Canadian tertiary hospitals between May 2006 and April 2010. All patients were considered high risk for surgical aortic valve replacement. Edwards-SAPIEN transcatheter heart valves (Edwards Lifesciences, Inc., Irvine, California) were used. Transfemoral or transapical access was selected, depending on the adequacy of femoral access. Access was transfemoral in 7 patients and transapical in 4 patients. There were no intraprocedural complications. Significant symptomatic and hemodynamic improvement was observed in 10 of 11 patients. Baseline aortic valve area of 0.65 ± 0.17 cm(2) and mean transaortic pressure gradient of 41 ± 22.4 mm Hg were improved to 1.45 ± 0.3 cm(2) and 13.4 ± 5.7 mm Hg, respectively. Two patients had moderate perivalvular leaks. At the 30-day follow-up there were 2 deaths due to multisystem failure in 2 transapical patients. In 1 patient an undersized, suboptimally positioned, unstable valve required late conversion to open surgery. TAVI in selected high-risk patients with severe BAV stenosis can be successfully performed with acceptable clinical outcomes but will require further evaluation. Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Fluid relief and check valve

DOEpatents

Blaedel, K.L.; Lord, S.C.; Murray, I.

1986-07-17

A passive fluid pressure relief and check valve allows the relief pressure to be slaved to a reference pressure independently of the exhaust pressure. The pressure relief valve is embodied by a submerged vent line in a sealing fluid, the relief pressure being a function of the submerged depth. A check valve is embodied by a vertical column of fluid (the maximum back pressure being a function of the height of the column of fluid). The pressure is vented into an exhaust system which keeps the exhaust out of the area providing the reference pressure.

Valve for fluid control

DOEpatents

Oborny, Michael C.; Paul, Phillip H.; Hencken, Kenneth R.; Frye-Mason, Gregory C.; Manginell, Ronald P.

2001-01-01

A valve for controlling fluid flows. This valve, which includes both an actuation device and a valve body provides: the ability to incorporate both the actuation device and valve into a unitary structure that can be placed onto a microchip, the ability to generate higher actuation pressures and thus control higher fluid pressures than conventional microvalves, and a device that draws only microwatts of power. An electrokinetic pump that converts electric potential to hydraulic force is used to operate, or actuate, the valve.

High precision high flow range control valve

DOEpatents

McCray, J.A.

1999-07-13

A fluid control valve is described having a valve housing having first and second valve housing openings for the ingress and egress of fluid through the control valve. Disposed within a void formed by the control valve is a sleeve having at least one sleeve opening to permit the flow of fluid therethrough. A flow restricter travels within the sleeve to progressively block off the sleeve opening and thereby control flow. A fluid passageway is formed between the first valve housing opening and the outer surface of the sleeve. A second fluid passageway is formed between the inside of the sleeve and the second valve housing opening. Neither fluid passageway contains more than one 90 [degree] turn. In the preferred embodiment only one of the two fluid passageways contains a 90[degree] turn. In another embodiment, the control valve housing is bifurcated by a control surface having control surface opening disposed therethrough. A flow restricter is in slidable contact with the control surface to restrict flow of fluid through the control surface openings. 12 figs.

High precision high flow range control valve

DOEpatents

McCray, John A.

1999-01-01

A fluid control valve is described having a valve housing having first and second valve housing openings for the ingress and egress of fluid through the control valve. Disposed within a void formed by the control valve is a sleeve having at least one sleeve opening to permit the flow of fluid therethrough. A flow restricter travels within the sleeve to progressively block off the sleeve opening and thereby control flow. A fluid passageway is formed between the first valve housing opening and the outer surface of the sleeve. A second fluid passageway is formed between the inside of the sleeve and the second valve housing opening. Neither fluid passageway contains more than one 90.degree. turn. In the preferred embodiment only one of the two fluid passageways contains a 90.degree. turn. In another embodiment, the control valve housing is bifurcated by a control surface having control surface opening disposed therethrough. A flow restricter is in slidable contact with the control surface to restrict flow of fluid through the control surface openings.

Miniaturized Single-Shot Valve and its Application to the ExoMars Pasteur Payload

NASA Technical Reports Server (NTRS)

Muller, Pierre; Henkel, Hartmut; Klinkner, Sabine

2010-01-01

Hermetically sealing a gas tank and opening it into tubing under telecommand control is a function required in various space instruments. There are a number of space valves that are power saving, withstand vibration, and do not contaminate the gas. But none of them combines these features with low mass and the ability to withstand temperatures of 130 C during the sterilization process mandatory for planetary missions. In this paper, a novel miniature valve is presented, which is particularly adapted to space applications. It is electrically actuated, utilizing a bimetallic snap-disc that pierces a metallic membrane by a needle pin, thereby opening the valve. The design of this single-shot valve is such that it allows it to withstand a temperature of 130 C and a pressure of 50 bars. The valve is also lightweight (6.62 g) and it requires only 9 W to operate.

40 CFR 265.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service...

Valve malfunction detection apparatus

NASA Astrophysics Data System (ADS)

Burley, Richard K.

1993-07-01

A detection system is provided for sensing a malfunction of a valve having an outlet connected to an end of a first pipe through which pressurized fluid may be flowed in a downstream direction away from the valve. The system includes a bypass pipe connected at its opposite ends to the first pipe and operative to bypass a portion of the fluid flow therethrough around a predetermined section thereof. A housing is interiorly divided by a flexible diaphragm into first and second opposite chambers which are respectively communicated with the first pipe section and the bypass pipe, the diaphragm being spring-biased toward the second chamber. The diaphragm housing cooperates with check valves and orifices connected in the two pipes to create and maintain a negative pressure in the first pipe section in response to closure of the valve during pressurized flow through the first pipe. A pressure switch senses the negative pressure and transmits a signal indicative thereof to a computer. Upon cessation of the signal while the valve is still closed, the computer responsively generates a signal indicating that the valve, or another portion of the detection system, is leaking.

Valve malfunction detection apparatus

NASA Technical Reports Server (NTRS)

Burley, Richard K. (Inventor)

1993-01-01

A detection system is provided for sensing a malfunction of a valve having an outlet connected to an end of a first pipe through which pressurized fluid may be flowed in a downstream direction away from the valve. The system includes a bypass pipe connected at its opposite ends to the first pipe and operative to bypass a portion of the fluid flow therethrough around a predetermined section thereof. A housing is interiorly divided by a flexible diaphragm into first and second opposite chambers which are respectively communicated with the first pipe section and the bypass pipe, the diaphragm being spring-biased toward the second chamber. The diaphragm housing cooperates with check valves and orifices connected in the two pipes to create and maintain a negative pressure in the first pipe section in response to closure of the valve during pressurized flow through the first pipe. A pressure switch senses the negative pressure and transmits a signal indicative thereof to a computer. Upon cessation of the signal while the valve is still closed, the computer responsively generates a signal indicating that the valve, or another portion of the detection system, is leaking.

Automatic shutoff valve

NASA Technical Reports Server (NTRS)

Hawkins, S. F.; Overbey, C. W.

1980-01-01

Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

The predictive value of external continuous lumbar drainage, with cerebrospinal fluid outflow controlled by medium pressure valve, in normal pressure hydrocephalus.

PubMed

Panagiotopoulos, V; Konstantinou, D; Kalogeropoulos, A; Maraziotis, T

2005-09-01

Although sporadic studies have described temporary external cerebrospinal fluid (CSF) lumbar drainage as a highly accurate test for predicting the outcome after ventricular shunting in normal pressure hydrocephalus (NPH) patients, a more recent study reports that the positive predictive value of external lumbar drainage (ELD) is high but the negative predictive value is deceptively low. Therefore, we conducted a prospective study in order to evaluate the predictive value of a continuous ELD, with CSF outflow controlled by medium pressure valve, in NPH patients. Twenty-seven patients with presumed NPH were admitted to our department and CSF drainage was carried out by a temporary (ELD) with CSF outflow controlled by a medium pressure valve for five days. All patients received a ventriculoperitoneal shunt using a medium pressure valve based upon preoperative clinical and radiographic criteria of NPH, regardless of ELD outcome. Clinical evaluation of gait disturbances, urinary incontinence and mental status, and radiological evaluation with brain CT was performed prior to and after ELD test, as well as three months after shunting. Twenty-two patients were finally shunted and included in this study. In a three-month follow-up, using a previously validated score system, overall improvement after permanent shunting correlated well to improvement after ELD test (Spearman's rho = 0.462, p = 0.03). When considering any degree of improvement as a positive response, ELD test yielded high positive predictive values for all individual parameters (gait disturbances 94%, 95% CI 71%-100%, urinary incontinence 100%, 95% CI 66%-100%, and mental status 100%, 95% CI 66%-100%) but negative predictive values were low (< 50%) except for cognitive impairment (85%, 95% CI 55%-98%). This study suggests that a positive ELD-valve system test should be considered a reliable criterion for preoperative selection of shunt-responsive NPH patients. In case of a negative ELD-valve system test

Assessment of RELAP5/MOD2 against a pressurizer spray valve inadverted fully opening transient and recovery by natural circulation in Jose Cabrera Nuclear Station

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

Arroyo, R.; Rebollo, L.

1993-06-01

This document presents the comparison between the simulation results and the plant measurements of a real event that took place in JOSE CABRERA nuclear power plant in August 30th, 1984. The event was originated by the total, continuous and inadverted opening of the pressurizer spray valve PCV-400A. JOSE CABRERA power plant is a single loop Westinghouse PWR belonging to UNION ELECTRICA FENOSA, S.A. (UNION FENOSA), an Spanish utility which participates in the International Code Assessment and Applications Program (ICAP) as a member of UNIDAD ELECTRICA, S.A. (UNESA). This is the second of its two contributions to the Program: the firstmore » one was an application case and this is an assessment one. The simulation has been performed using the RELAP5/MOD2 cycle 36.04 code, running on a CDC CYBER 180/830 computer under NOS 2.5 operating system. The main phenomena have been calculated correctly and some conclusions about the 3D characteristics of the condensation due to the spray and its simulation with a 1D tool have been got.« less

Fast acting check valve

NASA Technical Reports Server (NTRS)

Perkins, Gerald S. (Inventor)

1979-01-01

A check valve which closes more rapidly to prevent wearing of the valve seat and of the valve member that seals thereagainst, including a solenoid or other actuator that aids the normal spring to quickly close the valve at approximately the time when downpath fluid flow would stop, the actuator then being deenergized. The control circuit that operates the actuator can include a pair of pressure sensors sensing pressure both upstream and downstream from the valve seat. Where the valve is utilized to control flow to or from a piston pump, energization of the actuator can be controlled by sensing when the pump piston reaches its extreme of travel.

Modification and performance evaluation of a mono-valve engine

NASA Astrophysics Data System (ADS)

Behrens, Justin W.

A four-stroke engine utilizing one tappet valve for both the intake and exhaust gas exchange processes has been built and evaluated. The engine operates under its own power, but has a reduced power capacity than the conventional 2-valve engine. The reduction in power is traced to higher than expected amounts of exhaust gases flowing back into the intake system. Design changes to the cylinder head will fix the back flow problems, but the future capacity of mono-valve engine technology cannot be estimated. The back flow of exhaust gases increases the exhaust gas recirculation (EGR) rate and deteriorates combustion. Intake pressure data shows the mono-valve engine requires an advanced intake valve closing (IVC) time to prevent back flow of charge air. A single actuation camshaft with advanced IVC was tested in the mono-valve engine, and was found to improve exhaust scavenging at TDC and nearly eliminated all charge air back flow at IVC. The optimum IVC timing is shown to be approximately 30 crank angle degrees after BDC. The mono-valve cylinder head utilizes a rotary valve positioned above the tappet valve. The open spaces inside the rotary valveand between the rotary valve and tappet valve represent a common volume that needs to be reduced in order to reduce the base EGR rate. Multiple rotary valve configurations were tested, and the size of the common volume was found to have no effect on back flow but a direct effect on the EGR rate and engine performance. The position of the rotary valve with respect to crank angle has a direct effect on the scavenging process. Optimum scavenging occurs when the intake port is opened just after TDC.

40 CFR 65.110 - Standards: Pumps, valves, connectors, and agitators in heavy liquid service; pressure relief...

Code of Federal Regulations, 2011 CFR

2011-07-01

..., and agitators in heavy liquid service; pressure relief devices in liquid service; and instrumentation..., connectors, and agitators in heavy liquid service; pressure relief devices in liquid service; and..., valves, connectors, and agitators in heavy liquid service; pressure relief devices in light liquid or...

40 CFR 65.110 - Standards: Pumps, valves, connectors, and agitators in heavy liquid service; pressure relief...

Code of Federal Regulations, 2013 CFR

2013-07-01

..., and agitators in heavy liquid service; pressure relief devices in liquid service; and instrumentation..., connectors, and agitators in heavy liquid service; pressure relief devices in liquid service; and..., valves, connectors, and agitators in heavy liquid service; pressure relief devices in light liquid or...

40 CFR 65.110 - Standards: Pumps, valves, connectors, and agitators in heavy liquid service; pressure relief...

Code of Federal Regulations, 2014 CFR

2014-07-01

..., and agitators in heavy liquid service; pressure relief devices in liquid service; and instrumentation..., connectors, and agitators in heavy liquid service; pressure relief devices in liquid service; and..., valves, connectors, and agitators in heavy liquid service; pressure relief devices in light liquid or...

40 CFR 65.110 - Standards: Pumps, valves, connectors, and agitators in heavy liquid service; pressure relief...

Code of Federal Regulations, 2012 CFR

2012-07-01

..., and agitators in heavy liquid service; pressure relief devices in liquid service; and instrumentation..., connectors, and agitators in heavy liquid service; pressure relief devices in liquid service; and..., valves, connectors, and agitators in heavy liquid service; pressure relief devices in light liquid or...

40 CFR 65.110 - Standards: Pumps, valves, connectors, and agitators in heavy liquid service; pressure relief...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., and agitators in heavy liquid service; pressure relief devices in liquid service; and instrumentation..., connectors, and agitators in heavy liquid service; pressure relief devices in liquid service; and..., valves, connectors, and agitators in heavy liquid service; pressure relief devices in light liquid or...

[Coupled Analysis of Fluid-Structure Interaction of a Micro-Mechanical Valve for Glaucoma Drainage Devices].

PubMed

Siewert, S; Sämann, M; Schmidt, W; Stiehm, M; Falke, K; Grabow, N; Guthoff, R; Schmitz, K-P

2015-12-01

Glaucoma is the leading cause of irreversible blindness worldwide. In therapeutically refractory cases, alloplastic glaucoma drainage devices (GDD) are being increasingly used to decrease intraocular pressure. Current devices are mainly limited by fibrotic encapsulation and postoperative hypotension. Preliminary studies have described the development of a glaucoma microstent to control aqueous humour drainage from the anterior chamber into the suprachoroidal space. One focus of these studies was on the design of a micro-mechanical valve placed in the anterior chamber to inhibit postoperative hypotension. The present report describes the coupled analysis of fluid-structure interaction (FSI) as basis for future improvements in the design micro-mechanical valves. FSI analysis was carried out with ANSYS 14.5 software. Solid and fluid geometry were combined in a model, and the corresponding material properties of silicone (Silastic Rx-50) and water at room temperature were assigned. The meshing of the solid and fluid domains was carried out in accordance with the results of a convergence study with tetrahedron elements. Structural and fluid mechanical boundary conditions completed the model. The FSI analysis takes into account geometric non-linearity and adaptive remeshing to consider changing geometry. A valve opening pressure of 3.26 mmHg was derived from the FSI analysis and correlates well with the results of preliminary experimental fluid mechanical studies. Flow resistance was calculated from non-linear pressure-flow characteristics as 8.5 × 10(-3) mmHg/µl  · min(-1) and 2.7 × 10(-3) mmHg/µl  · min(-1), respectively before and after valve opening pressure is exceeded. FSI analysis indicated leakage flow before valve opening, which is due to the simplified model geometry. The presented bidirectional coupled FSI analysis is a powerful tool for the development of new designs of micro-mechanical valves for GDD and may help to minimise the time and cost

Zero-leak valve

NASA Technical Reports Server (NTRS)

Macglashan, W. F., Jr.

1980-01-01

Zero-leakage valve has fluid-sealing diaphragm support and flat sievelike sealing surface. Diaphragm-support valve is easy to fabricate and requires minimum maintenance. Potential applications include isolation valve for waste systems and remote air-actuated valve. Device is also useful in controlling flow of liquid fluorine and corrosive fluids at high pressures.

Control methods and valve arrangement for start-up and shutdown of pressurized combustion and gasification systems integrated with a gas turbine

DOEpatents

Provol, Steve J.; Russell, David B.; Isaksson, Matti J.

1994-01-01

A power plant having a system for converting coal to power in a gas turbine comprises a coal fed pressurized circulating bed for converting coal to pressurized gases, a gas turbine having a compressor for pressurizing air for the pressurized circulating bed and expander for receiving and expanding hot combustion gases for powering a generator, a first fast acting valve for controlling the pressurized air, a second fast acting valve means for controlling pressurized gas from the compressor to the expander.

Heart Valve Diseases

MedlinePlus

Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

Slide valve apparatus for internal combustion engine

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

Taylor, B.A.; McMahan, T.O.

This patent describes an internal combustion engine including a combustion cylinder having an opening at one end thereof, a piston mounted within the cylinder for coaxial reciprocable movement, a driven crankshaft, and a connecting rod connecting the crankshaft to the cylinder for linear reciprocable movement of the piston in response to the rotary movement of the crankshaft, a valve apparatus comprising: (a) a valve chamber extending longitudinally across and in fluid communication with the opening in the cylinder, (b) an intake valve plate having a longitudinal axis mounted within the valve chamber for slidable, reciprocable, longitudinal movement, (c) an exhaustmore » valve plate having a longitudinal axis mounted within the valve chamber alongside the intake valve plate for slidable, reciprocable, longitudinal movement and parallel to the longitudinal axis of the intake valve plate, (d) each of the valve plates having a plurality of longitudinally spaced valve ports therein, the valve ports comprising movable intake valve ports in the intake valve plate and movable exhaust valve ports in the exhaust valve plate, (e) the valve chamber comprising a planar wall on the opposite side of the valve plates from the cylinder opening and having a plurality of fixed valve ports therethrough. The fixed valve ports being equal in number and substantially equal in size and spacing as the movable intake and exhaust valve ports, whereby the movable intake valve ports are adapted to register with their corresponding fixed valve ports when the intake valve plate is in its intake operative position for opening fluid communication between the cylinder and the corresponding fixed valve ports.« less

Rotary pneumatic valve

DOEpatents

Hardee, Harry C.

1991-01-01

A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

Pressure Relief Devices

NASA Astrophysics Data System (ADS)

Manha, William D.

2010-09-01

leakage into the reference cavity. Since the burst discs are DFMR, a single burst disc would suffice, without adding the two leak-into-reference cavity failure modes. A single DFMR burst disc is preferable. An Alpha Magnetic Spectrometer - 02 burst disc assembly, with three-in-series burst discs test failure, necessitated the deletion of one of the burst discs, will be presented. Payload relief valves require periodic retests were extended significantly beyond the normal one year retest period because of the reduced ISS down mass capability which followed the Columbia accident. The acceptability of the extended retest period was determined by analysis, materials stability, benign environment, relatively inert fluid exposure, etc.(The policy letter, NC4-02-205 Guidelines for Certification and Verification of Pressure System Control Hardware, that permitted this action will be provided even though this application is not recommended for extending relief valve annual retest requirements.) The first crack pressure of a relief valve after an extended inactive period can be higher than the set crack pressure. Extrapolation of the extended inactive period and increased crack pressure could result in ineffective over pressure protection. Thus, relief valves with a ring or lever for activation are recommended so the relief valve can periodically be verified to open, functionality verified and the extended relief valve retest period should be discouraged. Stainless Steel cylindrical poppet-in-cylindrical housing check valves should never be used in a fluid with ions for an extended period of time, because the poppet is vulnerable to seizing or not functioning as a relief valve, even though the specifications, crack pressure, reseat pressure, maximum flow, and reseat leak look very much like the specifications for a relief valve. The technical reasons for this avoidance of using check valves as a relief valve will be discussed. The presentation will be summarized and recommendations

Split Venturi, Axially-Rotated Valve

DOEpatents

Walrath, David E.; Lindberg, William R.; Burgess, Robert K.

2000-08-29

The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane.

40 CFR 60.482-8 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and connectors. 60.482-8... Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid...

Study on a linear relationship between limited pressure difference and coil current of on/off valve and its influential factors.

PubMed

Zhang, Junzhi; Lv, Chen; Yue, Xiaowei; Li, Yutong; Yuan, Ye

2014-01-01

On/off solenoid valves with PWM control are widely used in all types of vehicle electro-hydraulic control systems respecting to their desirable properties of reliable, low cost and fast acting. However, it can hardly achieve a linear hydraulic modulation by using on/off valves mainly due to the nonlinear behaviors of valve dynamics and fluid, which affects the control accuracy significantly. In this paper, a linear relationship between limited pressure difference and coil current of an on/off valve in its critical closed state is proposed and illustrated, which has a great potential to be applied to improve hydraulic control performance. The hydraulic braking system of case study is modeled. The linear correspondence between limited pressure difference and coil current of the inlet valve is simulated and further verified experimentally. Based on validated simulation models, the impacts of key parameters are researched. The limited pressure difference affected by environmental temperatures is experimentally studied, and the amended linear relation is given according to the test data. © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Development and experimental characterization of a pneumatic valve actuated by a dielectric elastomer membrane

NASA Astrophysics Data System (ADS)

Hill, Marc; Rizzello, Gianluca; Seelecke, Stefan

2017-08-01

Due to their many features including lightweight and low energy consumption, dielectric elastomer (DE) membrane actuators are of interest for a number of industrial applications, such as pumping systems or valve control units. In particular, the use of DEs in valve control units offers advantages over traditional solenoid valves, including lower power requirements and relative simplicity in achieving proportional control. Additionally, DEs generate low thermal dissipation and are capable of virtually silent operation. The contribution of this work is the development of a new valve system based on a circular DE membrane pre-loaded with a linear spring. The valve is designed for pressurized air and operates by actuating a lever mechanism that opens and closes an outlet port. After presenting the operating principle and system design, several experiments are presented to compare actuator force, stroke, and dissipated energy for several pressure differentials and associated volume flows. It is observed that the DE-driven valve achieves a performance similar to a solenoid-based valve, while requiring a significantly lower amount of input energy. In addition, it is shown that DE-membrane valves can be controlled proportionally by simply adjusting the actuator voltage.

Valve assembly for internal combustion engine

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

Wakeman, R.J.; Shea, S.F.

1989-09-05

This patent describes an improvement in a valve assembly for an internal combustion engine of the type including a valve having a valve stem, a valve guideway for mounting this valve for reciprocal strokes between opened and seated position, and spring means for biasing the valve into the seated position. The improvement comprising a valve spool of greater cross-sectional diameter as compared to the valve stem, and a valve spool guideway within which the valve spool is movable during the strokes of the valve, an upper surface of the valve spool and a portion of the spool guideway collectively establishingmore » a damper chamber which varies in volume during the valve strokes. a feed passage for introducing oil into the damper chamber, and a bleed passage for discharging oil from the damper chamber. The bleed passages each laterally opening into the valve spool guideway.« less

VALVES FOR THE HIGH PRESSURE-HIGH TEMPERATURE (HP-HT) FLUORINATION SYSTEM. (Engineering Materials)

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

None

1963-10-31

This package contains two drawings of valves which eliminate errors in the gravimetric oxide dilution procedure of U/sup 235/ measurement. Isotopic contaminatioNonen in the high pressure fluorination reactor was corrected by changing the manner in which the Cu tubing joins the valve and by modification of the bellows. The compact inlet system was modified to improve the precision of the spectrometer analyses. Changes were raade in the basic leak and the air operator, which is a diaphragm-type valve, so that the setting of the flow level is controlled by the closure spring adjustment screw. This capillary-type leak has increased controlmore » range and sraooth control characteristics. It is simple to construct, is remotely operated and is free from corrosion failure. (F.S.)« less

Latching Solenoid-Operated Ball Valve

NASA Technical Reports Server (NTRS)

Brudnicki, Myron

1994-01-01

Proposed solenoid-operated ball valve latches in open or closed position until energized to change position. Electrical energy consumed only during opening or closing motion. Valve ball contains central channel through which fluid could flow. Made of highly magnetically permeable steel. When appropriate coil(s) energized by brief pulse (or pulses) of electrical current at appropriate polarity, ball rotates clockwise until permanent magnets come to rest against hard stops in housing, and inlet and outlet ports aligned with central channel so fluid flows through valve. Magnets adhere to stops by magnetic attraction, latching valve in open position. To close valve, appropriate coil(s) energized by pulse (or pulses) of appropriate polarity to generate magnetic forces rotating ball counterclockwise until magnets make contact with hard stops, and inlet and outlet ports sealed.

Clinical, echocardiographic, and Doppler imaging characteristics of mitral valve stenosis in two dogs.

PubMed

Fox, P R; Miller, M W; Liu, S K

1992-11-15

Mitral stenosis was diagnosed noninvasively by echocardiography and Doppler imaging in 2 Bull Terriers. Two-dimensional echocardiography revealed severe atrial and moderate left ventricular dilatation; severely reduced mitral valve opening excursion; doming of the cranial mitral valve leaflet into the left ventricle during diastole; thickened, nodular cranial mitral valve leaflets; and reduced mitral valve orifice. M-mode echocardiographic findings additionally indicated greatly diminished mitral valve E to F slope and abnormal caudal mitral valve leaflet motion. Color flow Doppler imaging revealed bright bursts of color with aliasing originating from the stenotic mitral valve orifice, extending into the left atrium during systole, and into the left atrium during diastole. Spectral Doppler recordings revealed transvalvular mitral valve gradients and prolonged pressure half-times. Necropsy performed on 1 dog revealed extremely thickened, nodular, and stiff mitral valves with short, thickened, and fused chordae tendineae. The diagnosis of mitral valve stenosis was easily facilitated with diagnostic ultrasonography.

Dual-latching solenoid-actuated valve assembly

NASA Technical Reports Server (NTRS)

Brudnicki, Myron J. (Inventor); Yang, Jeff (Inventor)

1994-01-01

A tube-type shutoff valve is electrically positioned to its open or closed position by a concentric electromagnetic solenoid. The valve is dual latching in that the armature of the solenoid maintains the sliding tube of the valve in an open or closed position by means of permanent magnets which are effective when current is not supplied to the solenoid. The valve may also be actuated manually.

A patient-specific aortic valve model based on moving resistive immersed implicit surfaces.

PubMed

Fedele, Marco; Faggiano, Elena; Dedè, Luca; Quarteroni, Alfio

2017-10-01

In this paper, we propose a full computational framework to simulate the hemodynamics in the aorta including the valve. Closed and open valve surfaces, as well as the lumen aorta, are reconstructed directly from medical images using new ad hoc algorithms, allowing a patient-specific simulation. The fluid dynamics problem that accounts from the movement of the valve is solved by a new 3D-0D fluid-structure interaction model in which the valve surface is implicitly represented through level set functions, yielding, in the Navier-Stokes equations, a resistive penalization term enforcing the blood to adhere to the valve leaflets. The dynamics of the valve between its closed and open position is modeled using a reduced geometric 0D model. At the discrete level, a finite element formulation is used and the SUPG stabilization is extended to include the resistive term in the Navier-Stokes equations. Then, after time discretization, the 3D fluid and 0D valve models are coupled through a staggered approach. This computational framework, applied to a patient-specific geometry and data, allows to simulate the movement of the valve, the sharp pressure jump occurring across the leaflets, and the blood flow pattern inside the aorta.

The effect of lymphatic valve morphology on fluid transport

NASA Astrophysics Data System (ADS)

Alexeev, Alexander; Ballard, Matthew; Nepiyushchikh, Zhanna; Dixon, Brandon

2016-11-01

The lymphatic vasculature is present in nearly all invertebrate tissue, and is essential in the transport of fluid and particles such as immune cells, antigens, proteins and lipids from the tissue to lymph nodes and to the venous circulation. Lymphatic vessels are made of up a series of contractile units that work together in harmony as "micro hearts" to pump fluid against a pressure gradient. Lymphatic valves are critical to this functionality, as they open and close with the oscillating pressure gradients from contractions, thus allowing flow in only one direction and leading to a net pumping effect. We use a hybrid lattice-Boltzmann lattice spring model which captures fluid-solid interactions through two-way coupling between a viscous fluid and lymphatic valves in a section of a lymphatic vessel to study the dynamics of lymphatic valves and their effect on fluid transport. Further, we investigate the effect of variations in valve geometry and material properties on fluid pumping. This work helps to increase our understanding of the mechanisms of lymphatic fluid transport, which has implications in a variety of pathologies, including cancer metastasis, autoimmunity, atherosclerosis and obesity. Support from NSF CMMI 1635133 is gratefully acknowledged.

Internal Acoustics of a Pintle Valve with Supercritical Helium Flow

NASA Technical Reports Server (NTRS)

Fishbach, Sean R.; Davis, R. Benjamin

2010-01-01

Large amplitude flow unsteadiness is a common phenomenon within the high flow rate ducts and valves associated with propulsion systems. Boundary layer noise, shear layers and vortex shedding are a few of the many sources of flow oscillations. The presence of lightly damped acoustic modes can organize and amplify these sources of flow perturbation, causing undesirable loading of internal parts. The present study investigates the self-induced acoustic environment within a pintle valve subject to high Reynolds Number flow of helium gas. Experiments were conducted to measure the internal pressure oscillations of the Ares I Launch Abort System (LAS) Attitude Control Motor (ACM) valve. The AGM consists of a solid propellant gas generator with eight pintle valves attached to the aft end. The pintle valve is designed to deliver variable upstream conditions to an attache( converging diverging nozzle. In order to investigate the full range of operating conditions 28 separate tests were conducted with varying pintle position and upstream pressure. Helium gas was utilized in order to closely mimic the speed of sound of the gas generator exhaust, minimizing required scaling during data analysis. The recordec pressure measurements were interrogated to multiple ends. The development of root mean square (RMS) value! versus Reynolds Number and Pintle position are important to creating bounding unsteady load curves for valve internal parts. Spectral analysis was also performed, helping to identify power spectral densities (PSD) of acoustic natural frequencies and boundary layer noise. An interesting and unexpected result was the identification of an acoustic mode within the valve which does not respond until the valve was over 60% open. Further, the response amplitude around this mode can be as large or larger than those associated with lower frequency modes.

Lamellar projections in the endolymphatic sac act as a relief valve to regulate inner ear pressure

PubMed Central

Swinburne, Ian A; Mosaliganti, Kishore R; Upadhyayula, Srigokul; Liu, Tsung-Li; Hildebrand, David G C; Tsai, Tony Y -C; Chen, Anzhi; Al-Obeidi, Ebaa; Fass, Anna K; Malhotra, Samir; Engert, Florian; Lichtman, Jeff W; Kirchausen, Tomas; Betzig, Eric

2018-01-01

The inner ear is a fluid-filled closed-epithelial structure whose function requires maintenance of an internal hydrostatic pressure and fluid composition. The endolymphatic sac (ES) is a dead-end epithelial tube connected to the inner ear whose function is unclear. ES defects can cause distended ear tissue, a pathology often seen in hearing and balance disorders. Using live imaging of zebrafish larvae, we reveal that the ES undergoes cycles of slow pressure-driven inflation followed by rapid deflation. Absence of these cycles in lmx1bb mutants leads to distended ear tissue. Using serial-section electron microscopy and adaptive optics lattice light-sheet microscopy, we find a pressure relief valve in the ES comprised of partially separated apical junctions and dynamic overlapping basal lamellae that separate under pressure to release fluid. We propose that this lmx1-dependent pressure relief valve is required to maintain fluid homeostasis in the inner ear and other fluid-filled cavities. PMID:29916365

Watts Bar Lock Valve Model Study

DTIC Science & Technology

2013-08-01

stream of the valve, and cavitation potential for various valve openings. Design modifications to improve performance were to be recommended. The...operation schedule to avoid gate openings with cavitation problems. This report provides results of the recent model experiments performed on the...the mid range openings. The noise is caused by cavitation in the culvert downstream of the filling valves. The vapor cavities that form from the low

High pressure air compressor valve fault diagnosis using feedforward neural networks

NASA Astrophysics Data System (ADS)

James Li, C.; Yu, Xueli

1995-09-01

Feedforward neural networks (FNNs) are developed and implemented to classify a four-stage high pressure air compressor into one of the following conditions: baseline, suction or exhaust valve faults. These FNNs are used for the compressor's automatic condition monitoring and fault diagnosis. Measurements of 39 variables are obtained under different baseline conditions and third-stage suction and exhaust valve faults. These variables include pressures and temperatures at all stages, voltage between phase aand phase b, voltage between phase band phase c, total three-phase real power, cooling water flow rate, etc. To reduce the number of variables, the amount of their discriminatory information is quantified by scattering matrices to identify statistical significant ones. Measurements of the selected variables are then used by a fully automatic structural and weight learning algorithm to construct three-layer FNNs to classify the compressor's condition. This learning algorithm requires neither guesses of initial weight values nor number of neurons in the hidden layer of an FNN. It takes an incremental approach in which a hidden neuron is trained by exemplars and then augmented to the existing network. These exemplars are then made orthogonal to the newly identified hidden neuron. They are subsequently used for the training of the next hidden neuron. The betterment continues until a desired accuracy is reached. After the neural networks are established, novel measurements from various conditions that haven't been previously seen by the FNNs are then used to evaluate their ability in fault diagnosis. The trained neural networks provide very accurate diagnosis for suction and discharge valve defects.

System Would Regulate Low Gas Pressure

NASA Technical Reports Server (NTRS)

Frazer, Robert E.

1994-01-01

System intended to maintain gases in containers at pressures near atmospheric. Includes ballast volume in form of underinflated balloon that communicates with working volume. Balloon housed in rigid chamber not subjected to extremes of temperature of working volume. Pressure in chamber surrounding balloon regulated at ambient atmospheric pressure or at constant small differential pressure above or below ambient. Expansion and contraction of balloon accommodates expansion or contraction of gas during operational heating or cooling in working volume, maintaining pressure in working volume at ambient or constant differential above or below ambient. Gas lost from system due to leakage or diffusion, low-pressure sensor responds, signaling valve actuators to supply more gas to working volume. If pressure rises too high, overpressure relief valve opens before excessive pressure damages system.

Particle image velocimetry study of pulsatile flow in bi-leaflet mechanical heart valves with image compensation method.

PubMed

Shi, Yubing; Yeo, Tony Joon Hock; Zhao, Yong; Hwang, Ned H C

2006-12-01

Particle Image Velocimetry (PIV) is an important technique in studying blood flow in heart valves. Previous PIV studies of flow around prosthetic heart valves had different research concentrations, and thus never provided the physical flow field pictures in a complete heart cycle, which compromised their pertinence for a better understanding of the valvular mechanism. In this study, a digital PIV (DPIV) investigation was carried out with improved accuracy, to analyse the pulsatile flow field around the bi-leaflet mechanical heart valve (MHV) in a complete heart cycle. For this purpose a pulsatile flow test rig was constructed to provide the necessary in vitro test environment, and the flow field around a St. Jude size 29 bi-leaflet MHV and a similar MHV model were studied under a simulated physiological pressure waveform with flow rate of 5.2 l/min and pulse rate at 72 beats/min. A phase-locking method was applied to gate the dynamic process of valve leaflet motions. A special image-processing program was applied to eliminate optical distortion caused by the difference in refractive indexes between the blood analogue fluid and the test section. Results clearly showed that, due to the presence of the two leaflets, the valvular flow conduit was partitioned into three flow channels. In the opening process, flow in the two side channels was first to develop under the presence of the forward pressure gradient. The flow in the central channel was developed much later at about the mid-stage of the opening process. Forward flows in all three channels were observed at the late stage of the opening process. At the early closing process, a backward flow developed first in the central channel. Under the influence of the reverse pressure gradient, the flow in the central channel first appeared to be disturbed, which was then transformed into backward flow. The backward flow in the central channel was found to be the main driving factor for the leaflet rotation in the valve

Magnetically operated check valve

NASA Technical Reports Server (NTRS)

Morris, Brian G. (Inventor); Bozeman, Richard J., Jr. (Inventor)

1994-01-01

A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

Magnetically operated check valve

NASA Astrophysics Data System (ADS)

Morris, Brian G.; Bozeman, Richard J., Jr.

1994-06-01

A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

Aerodynamic Shutoff Valve

NASA Technical Reports Server (NTRS)

Horstman, Raymond H.

1992-01-01

Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

Cryogenic Cam Butterfly Valve

NASA Technical Reports Server (NTRS)

McCormack, Kenneth J. (Inventor)

2016-01-01

A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

Aspirator increases relief valve poppet stroke

NASA Technical Reports Server (NTRS)

Biddle, M. E.

1967-01-01

Addition of an aspirator to a relief valve increases the valve poppet stroke under dynamic flow conditions. The aspirator allows poppet inlet dynamic forces to overcome relief valve spring force. It reduces the fluid pressure in the skirt cavity by providing a low pressure sense probe.

Solenoid Valve With Self-Compensation

NASA Technical Reports Server (NTRS)

Woeller, Fritz H.; Matsumoto, Yutaka

1987-01-01

New solenoid-operated miniature shutoff valve provides self-compensation of differential pressure forces that cause jamming or insufficient valve closure as in single-seal valves. Dual-seal valve is bidirectional. Valve simultaneously seals both inlet and outlet tubes by pressing single disk of silicone rubber against ends of both.

Valve for waste collection and storage

NASA Technical Reports Server (NTRS)

Thornton, William E., Jr. (Inventor); Whitmore, Henry B. (Inventor)

1990-01-01

A method and valve apparatus for collection of fecal matter designed to operate efficiently in a zero gravity environment is presented. The system comprises a waste collection area within a body having a seat opening. Low pressure within the waste collection area directs fecal matter away from the user's buttocks and prevents the escape of undersirable gases. The user actuates a piston covered with an absorbent pad that sweeps through the waste collection area to collect the fecal matter, scrub the waste collection area, press the waste against an end of the waste collection area and retracts, leaving the used pad. Multiple pads are provided on the piston to accommodate multiple uses of the system. Also a valve allows air to be drawn through the body, so the valve will not be plugged with fecal matter. A sheet feeder feeds fresh sheets of absorbent pads to a face of the piston with each actuation.

Transient flow characteristics of a high speed rotary valve

NASA Astrophysics Data System (ADS)

Browning, Patrick H.

Pressing economic and environmental concerns related to the performance of fossil fuel burning internal combustion engines have revitalized research in more efficient, cleaner burning combustion methods such as homogeneous charge compression ignition (HCCI). Although many variations of such engines now exist, several limiting factors have restrained the full potential of HCCI. A new method patented by West Virginia University (WVU) called Compression Ignition by Air Injection (CIBAI) may help broaden the range of effective HCCI operation. The CIBAI process is ideally facilitated by operating two synchronized piston-cylinders mounted head-to-head with one of the cylinders filled with a homogeneous mixture of air and fuel and the other cylinder filled with air. A specialized valve called the cylinder connecting valve (CCV) separates the two cylinders, opens just before reaching top dead center (TDC), and allows the injection air into the charge to achieve autoignition. The CCV remains open during the entire power stroke such that upon ignition the rapid pressure rise in the charge cylinder forces mass flow back through the CCV into the air-only cylinder. The limited mass transfer between the cylinders through the CCV limits the theoretical auto ignition timing capabilities and thermal efficiency of the CIBAI cycle. Research has been performed to: (1) Experimentally measure the transient behavior of a potential CCV design during valve opening between two chambers maintained at constant pressure and again at constant volume; (2) Develop a modified theoretical CCV mass flow model based upon the measured cold flow valve performance that is capable of predicting the operating conditions required for successful mixture autoignition; (3) Make recommendations for future CCV designs to maximize CIBAI combustion range. Results indicate that the modified-ball CCV design offers suitable transient flow qualities required for application to the CIBAI concept. Mass injection events

49 CFR 192.181 - Distribution line valves.

Code of Federal Regulations, 2010 CFR

2010-10-01

... line valves. (a) Each high-pressure distribution system must have valves spaced so as to reduce the... pressure, the size of the mains, and the local physical conditions. (b) Each regulator station controlling the flow or pressure of gas in a distribution system must have a valve installed on the inlet piping...

A new beating-heart mitral and aortic valve assessment model with implications for valve intervention training.

PubMed

Bouma, Wobbe; Jainandunsing, Jayant S; Khamooshian, Arash; van der Harst, Pim; Mariani, Massimo A; Natour, Ehsan

2017-02-01

A thorough understanding of mitral and aortic valve motion dynamics is essential in mastering the skills necessary for performing successful valve intervention (open or transcatheter repair or replacement). We describe a reproducible and versatile beating-heart mitral and aortic valve assessment and valve intervention training model in human cadavers. The model is constructed by bilateral ligation of the pulmonary veins, ligation of the supra-aortic arteries, creating a shunt between the descending thoracic aorta and the left atrial appendage with a vascular prosthesis, anastomizing a vascular prosthesis to the apex and positioning an intra-aortic balloon pump (IABP) in the vascular prosthesis, cross-clamping the descending thoracic aorta, and finally placing a fluid line in the shunt prosthesis. The left ventricle is filled with saline to the desired pressure through the fluid line, and the IABP is switched on and set to a desired frequency (usually 60-80 bpm). Prerepair valve dynamic motion can be studied under direct endoscopic visualization. After assessment, the IABP is switched off, and valve intervention training can be performed using standard techniques. This high-fidelity simulation model has known limitations, but provides a realistic environment with an actual beating (human) heart, which is of incremental value. The model provides a unique opportunity to fill a beating heart with saline and to study prerepair mitral and aortic valve dynamic motion under direct endoscopic visualization. The entire set-up provides a versatile beating-heart mitral and aortic valve assessment model, which may have important implications for future valve intervention training. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Thermodynamic Pressure/Temperature Transducer Health Check

NASA Technical Reports Server (NTRS)

Immer, Christopher D. (Inventor); Eckhoff, Anthony (Inventor); Medelius, Pedro J. (Inventor); Deyoe, Richard T. (Inventor); Starr, Stanley O. (Inventor)

2004-01-01

A device and procedure for checking the health of a pressure transducer in situ is provided. The procedure includes measuring a fixed change in pressure above ambient pressure and a fixed change in pressure below ambient pressure. This is done by first sealing an enclosed volume around the transducer with a valve. A piston inside the sealed volume is increasing the pressure. A fixed pressure below ambient pressure is obtained by opening the valve, driving the piston The output of the pressure transducer is recorded for both the overpressuring and the underpressuring. By comparing this data with data taken during a preoperative calibration, the health of the transducer is determined from the linearity, the hysteresis, and the repeatability of its output. The further addition of a thermometer allows constant offset error in the transducer output to be determined.

Are anticoagulant independent mechanical valves within reach-fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models.

PubMed

Scotten, Lawrence N; Siegel, Rolland

2015-08-01

Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring

Are anticoagulant independent mechanical valves within reach—fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models

PubMed Central

Siegel, Rolland

2015-01-01

Background Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Methods Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Results Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Conclusions Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration

Solenoid valve performance characteristics studied

NASA Technical Reports Server (NTRS)

Abe, J. T.; Blackburn, S.

1970-01-01

Current and voltage waveforms of a solenoid coil are recorded as the valve opens and closes. Analysis of the waveforms with respect to time and the phase of the valve cycle accurately describes valve performance.

The closing behavior of mechanical aortic heart valve prostheses.

PubMed

Lu, Po-Chien; Liu, Jia-Shing; Huang, Ren-Hong; Lo, Chi-Wen; Lai, Ho-Cheng; Hwang, Ned H C

2004-01-01

Mechanical artificial heart valves rely on reverse flow to close their leaflets. This mechanism creates regurgitation and water hammer effects that may form cavitations, damage blood cells, and cause thromboembolism. This study analyzes closing mechanisms of monoleaflet (Medtronic Hall 27), bileaflet (Carbo-Medics 27; St. Jude Medical 27; Duromedics 29), and trileaflet valves in a circulatory mock loop, including an aortic root with three sinuses. Downstream flow field velocity was measured via digital particle image velocimetry (DPIV). A high speed camera (PIVCAM 10-30 CCD video camera) tracked leaflet movement at 1000 frames/s. All valves open in 40-50 msec, but monoleaflet and bileaflet valves close in much less time (< 35 msec) than the trileaflet valve (>75 msec). During acceleration phase of systole, the monoleaflet forms a major and minor flow, the bileaflet has three jet flows, and the trileaflet produces a single central flow like physiologic valves. In deceleration phase, the aortic sinus vortices hinder monoleaflet and bileaflet valve closure until reverse flows and high negative transvalvular pressure push the leaflets rapidly for a hard closure. Conversely, the vortices help close the trileaflet valve more softly, probably causing less damage, lessening back flow, and providing a washing effect that may prevent thrombosis formation.

Mitral Valve Prolapse

MedlinePlus

... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ... our brochures Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

Bacterial translocation and plasma cytokines during transcatheter and open-heart aortic valve implantation.

PubMed

Adrie, Christophe; Parlato, Marianna; Salmi, Lynda; Adib-Conquy, Minou; Bical, Olivier; Deleuze, Philippe; Fitting, Catherine; Cavaillon, Jean Marc; Monchi, Mehran

2015-01-01

To determine whether the good safety profile of transarterial aortic valve implantation (TAVI) is related to lower levels of systemic bacterial translocation and systemic inflammation compared with open-heart surgery. Transcatheter aortic valve implantation via the transfemoral approach is increasingly used in very high-risk patients with aortic stenosis. The outcomes seem similar to those after open-heart aortic valve replacement (OHAVR). Each of 26 consecutive high-risk patients (EuroSCORE >20% for risk of operative death) who underwent TAVI (cases) was matched to the first low-risk patient treated next in our department using elective OHAVR without coronary artery bypass (control subjects). We collected severity, outcome, and echocardiography indicators before and after surgery; complications; proinflammatory cytokine levels; and markers for microbial translocation. Despite greater illness severity, the TAVI patients had significantly lower vasopressor agent requirements, lower delirium rates, shorter hospital stays, and better hemodynamic findings compared with OHAVR patients. Vascular complications were more common after TAVI than after OHAVR (12, with seven requiring interventional therapy vs. 0, P = 0.006). Patients who underwent TAVI had lower blood transfusion requirements. Two TAVI patients died: one from iliac artery injury and the other from intracardiac prosthesis migration. Patients who underwent TAVI had lower plasma levels of endotoxin and bacterial peptidoglycan, as well as lower proinflammatory cytokine levels, suggesting less gastrointestinal bacterial translocation compared with OHAVR. Compared with OHAVR, TAVI was associated with decreases in bacterial translocation and inflammation. These differences may explain the lower delirium rate and better hemodynamic stability observed, despite the greater disease severity in TAVI patients.

Magnetically operated check valve

NASA Astrophysics Data System (ADS)

Morris, Brian G.; Bozeman, Richard J., Jr.

1993-03-01

A magnetically operated check valve is disclosed having, in one aspect, a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

Fast acting multiple element valve

DOEpatents

Yang, Jefferson Y. S.; Wada, James M.

1991-01-01

A plurality of slide valve elements having plural axial-spaced annular parts and an internal slide are inserted into a bulkhead in a fluid conduit from a downstream side of the bulkhead, locked in place by a bayonet coupling and set screw, and project through the bulkhead into the upstream conduit. Pneumatic lines connecting the slide valve element actuator to pilot valves are brought out the throat of the valve element to the downstream side. Pilot valves are radially spaced around the exterior of the valve to permit the pneumatic lines to be made identical, thereby to minimize adverse timing tolerances in operation due to pressure variations. Ring manifolds surround the valve adjacent respective pilot valve arrangements to further reduce adverse timing tolerances due to pressure variations, the manifolds being directly connected to the respective pilot valves. Position sensors are provided the valve element slides to signal the precise time at which a slide reaches or passes through a particular point in its stroke to initiate a calibrated timing function.

Lightweight Motorized Valve

NASA Technical Reports Server (NTRS)

Gonzalez, R.; Vandewalle, J.

1986-01-01

Redesigned actuator assembly weighs 50 percent less. Isolator valve operated by ac motor instead of usual dc solenoid. Valve weighs only 3 lb (1.4 kg). New valve functions with either two-phase or three-phase power. Developed for isolating fluids in propellant tanks, manifolds, and interconnecting lines of Space Shuttle reaction control and orbital maneuvering subsystems, valve suited to applications in which leakage must be kept to minimum at high pressure differences - in petroleum and chemical processing.

Refuge alternatives relief valve testing and design

PubMed Central

Lutz, T.J.; Bissert, P.T.; Homce, G.T.; Yonkey, J.A.

2016-01-01

The U.S. National Institute for Occupational Safety and Health (NIOSH) has been researching refuge alternatives (RAs) since 2007. RAs typically have built-in pressure relief valves (PRVs) to prevent the unit from reaching unsafe pressures. The U.S. Mine Safety and Health Administration requires that these valves vent the chamber at a maximum pressure of 1.25 kPa (0.18 psi, 5.0 in. H2O), or as specified by the manufacturer, above mine atmospheric pressure in the RA. To facilitate PRV testing, an instrumented benchtop test fixture was developed using an off-the-shelf centrifugal blower and ductwork. Relief pressures and flow characteristics were measured for three units: (1) a modified polyvinyl chloride check valve, (2) an off-the-shelf brass/cast-iron butterfly check valve and (3) a commercially available valve that was designed specifically for one manufacturer’s steel prefabricated RAs and had been adapted for use in one mine operator’s built-in-place RA. PRVs used in tent-style RAs were not investigated. The units were tested with different modifications and configurations in order to check compliance with Title 30 Code of Federal Regulations, or 30 CFR, regulations. The commercially available relief valve did not meet the 30 CFR relief pressure specification but may meet the manufacturer’s specification. Alternative valve designs were modified to meet the 30 CFR relief pressure specification, but all valve designs will need further design research to examine survivability in the event of a 103 kPa (15.0 psi) impulse overpressure during a disaster. PMID:28018003

Electrokinetic high pressure hydraulic system

DOEpatents

Paul, Phillip H.; Rakestraw, David J.; Arnold, Don W.; Hencken, Kenneth R.; Schoeniger, Joseph S.; Neyer, David W.

2001-01-01

An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based systems. The pump uses electro-osmotic flow to provide a high pressure hydraulic system, having no moving mechanical parts, for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and manipulating fluid flow generally and in capillary-based systems (Microsystems), in particular. The compact nature of the inventive high pressure hydraulic pump provides the ability to construct a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, the ability to run samples in parallel, and field portability. Control of pressure and solvent flow rate is achieved by controlling the voltage applied to an electrokinetic pump.

Electrokinetic high pressure hydraulic system

DOEpatents

Paul, Phillip H.; Rakestraw, David J.; Arnold, Don W.; Hencken, Kenneth R.; Schoeniger, Joseph S.; Neyer, David W.

2003-06-03

An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based system. The pump uses electro-osmotic flow to provide a high pressure hydraulic system, having no moving mechanical parts, for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and manipulating fluid flow generally and in capillary-based systems (microsystems), in particular. The compact nature of the inventive high pressure hydraulic pump provides the ability to construct a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, the ability to run samples in parallel, and field portability. Control of pressure and solvent flow rate is achieved by controlling the voltage applied to an electrokinetic pump.

Current treatment of normal-pressure hydrocephalus: comparison of flow-regulated and differential-pressure shunt valves.

PubMed

Weiner, H L; Constantini, S; Cohen, H; Wisoff, J H

1995-11-01

FROM THE RECORDS of approximately 1500 shunt operations performed between 1987 and 1992, we identified 37 adults between ages 38 and 86 years (mean, 70 yr) with the normal-pressure hydrocephalus (NPH) syndrome who underwent surgery by a single surgeon. Since 1990, we have routinely used a flow-regulated shunt system (Orbis-Sigma valve [OSV]; Cordis Corporation, Miami, FL) in these patients. In this study, we compared the OSV system with conventional differential-pressure (DP) shunt systems uniformly used before 1990. This series (n = 37) consisted of 62% men (n = 23) and 38% women (n = 14). We excluded all patients with hydrocephalus associated with central nervous system neoplasms, intracerebral hemorrhage, or trauma as well those with radiographically documented late-onset aqueductal stenosis. All patients presented with the NPH clinical syndrome, chiefly with magnetic gait. In addition, 75% of patients experienced cognitive loss and 59% experienced urinary incontinence. The mean duration of preoperative symptoms was 35 months (range, 7-120 mo). Eight patients (22%) had undergone previous shunting procedures before referral to our service. A total of 89 shunt operations were performed in the 37 patients. Using actuarial methods and controlling for a history of prior shunt surgery, we found no significant difference in the time to initial malfunction (shunt survival) between the OSV and the DP shunts. There were three subdural hematomas and one infection in the OSV group compared with no complications in the DP valve group (P = 0.11). Thirty-six patients were available for follow-up, at a mean of 14 months after surgery. Nearly 90% of all patients experienced improvement in gait after shunting, regardless of the valve system that was used. There was one unrelated death. Realizing the limitations of a retrospective analysis and on the basis of the limited number of patients in this study, we conclude that using actuarial methods, we found no significant difference

A PDMS membrane microvalve with one-dimensional line valve seat for robust microfluidics

NASA Astrophysics Data System (ADS)

Park, Chin-Sung; Hwang, Kyu-Youn; Jung, Wonjong; Namkoong, Kak; Chung, Wonseok; Kim, Joon-Ho; Huh, Nam

2014-02-01

We have developed a monolithic polydimethylsiloxane (PDMS) membrane microvalve with an isotropically etched valve seat for robust microfluidics. In order to avoid bonding or sticking of the PDMS membrane to the valve seat during the bonding process, the valve seat was wet-etched to be a one-dimensional line instead of a plane. The simple wet-etching technique allowed for the fabrication of an anti-bonding architecture in a scalable manner, and it intrinsically prevented contact between the PDMS membrane and valve seat when no external force was applied (i.e., normally open). This approach enables the permanent device assembly so that the microfluidic chip can be operable in a wide range of fluid pressures (e.g., over 200 kPa) without any leakage and sticking problems.

Transcatheter Pulmonary Valve Replacement by Hybrid Approach Using a Novel Polymeric Prosthetic Heart Valve: Proof of Concept in Sheep

PubMed Central

Xu, Tong-yi; Zhang, Zhi-gang; Li, Xin; Han, Lin; Xu, Zhi-yun

2014-01-01

Background Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach. Methods We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE) coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve), weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically. Findings Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen

Design and test of a simple fast electromagnetic inductive gas valve for planar pulsed inductive plasma thruster

NASA Astrophysics Data System (ADS)

Guo, Dawei; Cheng, Mousen; Li, Xiaokang

2017-10-01

In support of our planar pulsed inductive plasma thruster research, a fast electromagnetic inductive valve for a gas propellant injection system has been built and tested. A new and important design feature is the use of a conical diaphragm as the action part, which greatly contributes to the virtue of simplicity for adopting the resultant force of the diaphragm deformation as the closing force. An optical transmission technique is adopted to measure the opening and closing characters of the valve while the gas throughput is determined by measuring the pressure change per pulse in a test chamber with a capacitance manometer. The experimental results revealed that the delay time before the valve reaction is less than 40 μs, and the valve pulse width is no longer than 160 μs full width at half maximum. The valve delivers 0-2.5 mg of argon gas per pulse varied by adjusting the drive voltage and gas pressure.

Design and test of a simple fast electromagnetic inductive gas valve for planar pulsed inductive plasma thruster.

PubMed

Guo, Dawei; Cheng, Mousen; Li, Xiaokang

2017-10-01

In support of our planar pulsed inductive plasma thruster research, a fast electromagnetic inductive valve for a gas propellant injection system has been built and tested. A new and important design feature is the use of a conical diaphragm as the action part, which greatly contributes to the virtue of simplicity for adopting the resultant force of the diaphragm deformation as the closing force. An optical transmission technique is adopted to measure the opening and closing characters of the valve while the gas throughput is determined by measuring the pressure change per pulse in a test chamber with a capacitance manometer. The experimental results revealed that the delay time before the valve reaction is less than 40 μs, and the valve pulse width is no longer than 160 μs full width at half maximum. The valve delivers 0-2.5 mg of argon gas per pulse varied by adjusting the drive voltage and gas pressure.

Flow Split Venturi, Axially-Rotated Valve

DOEpatents

Walrath, David E.; Lindberg, William R.; Burgess, Robert K.; LaBelle, James

2000-02-22

The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. An axially aligned outlet may also increase the flow efficiency. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane. A seal separator may increase the useful life of the seal between the fixed and rotatable portions.

Valving for controlling a fluid-driven reciprocating apparatus

DOEpatents

Whitehead, John C.

1995-01-01

A pair of control valve assemblies for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve assembly is switched by a pressure signal depending on the state of its counterpart's piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow. Each of the valve assemblies uses an intake-exhaust valve and a signal valve with the signal valve of one pump being connected to be pressure responsive to the piston of the opposite cylinder or pump.

Propellant actuated nuclear reactor steam depressurization valve

DOEpatents

Ehrke, Alan C.; Knepp, John B.; Skoda, George I.

1992-01-01

A nuclear fission reactor combined with a propellant actuated depressurization and/or water injection valve is disclosed. The depressurization valve releases pressure from a water cooled, steam producing nuclear reactor when required to insure the safety of the reactor. Depressurization of the reactor pressure vessel enables gravity feeding of supplementary coolant water through the water injection valve to the reactor pressure vessel to prevent damage to the fuel core.

Noise generated by flow through large butterfly valves

NASA Technical Reports Server (NTRS)

Huff, Ronald G.

1987-01-01

A large butterfly valve (1.37 m diam) was acoustically tested to measure the noise generated and propagating in both the upstream and downstream directions. The experimental investigation used wall mounted pressure transducers to measure the fluctuating component of the pipe static pressure upstream and downstream of the valve. Microphones upstream of the pipe inlet and located in a plenum were used to measure the noise radiated from the valve in the upstream direction. Comparison of the wall pressure downstream of the valve to a prediction were made. Reasonable agreement was obtained with the valve operating at a choked condition. The noise upstream of the valve is 30 dB less than that measured downstream.

BAKABLE ULTRA-HIGH VACUUM VALVE

DOEpatents

Mark, J.T.; Gantz, I.H.

1962-07-10

S>This patent relates to a valve useful in applications involving successively closing and opening a communication between a chamber evacuated to an ultra-high vacuum condition of the order of 10/sup -10/ millimeters of mercury and another chamber or the ambient. The valve is capable of withstanding extended baking at 450 deg C and repeated opening and closing without repiacement of the valve seat (approximately 200 cycle limit). The seal is formed by mutual interdiffusion weld, coerced by a pneumatic actuator. (AEC)

Validation of a noninvasive test routinely used in otology for the diagnosis of cerebrospinal fluid shunt malfunction in patients with normal pressure hydrocephalus.

PubMed

Sakka, Laurent; Chomicki, Alexandre; Gabrillargues, Jean; Khalil, Toufic; Chazal, Jean; Avan, Paul

2016-02-01

Ventriculoperitoneal shunting is the first-line treatment for normal pressure hydrocephalus. Noninvasive auditory tests based on recorded otoacoustic emissions were assessed, as currently used for universal neonatal hearing screenings, for the diagnosis of cerebrospinal fluid shunt malfunction. The test was designed based on previous works, which demonstrated that an intracranial pressure change induces a proportional, characteristic, otoacoustic-emission phase shift. Forty-four patients with normal pressure hydrocephalus (23 idiopathic and 21 secondary cases) were included in this prospective observational study. The male:female sex ratio was 1.44, the age range was 21-87 years (mean age 64.3 years), and the range of the follow-up period was 1-3 years (mean 20 months). Patients were implanted with a Sophy SU8 adjustable-pressure valve as the ventriculoperitoneal shunt. The phase shifts of otoacoustic emissions in response to body tilt were measured preoperatively, immediately postoperatively, and at 3-6 months, 7-15 months, 16-24 months, and more than 24 months postoperatively. Three groups were enrolled: Group 1, 19 patients who required no valve opening-pressure adjustment; Group 2, 18 patients who required valve opening-pressure adjustments; and Group 3, 7 patients who required valve replacement. In Group 1, phase shift, which was positive before surgery, became steadily negative after surgery and during the follow-up. In Group 2, phase shift, which was positive before surgery, became negative immediately after surgery and increasingly negative after a decrease in the valve-opening pressure. In Group 3, phase shift was positive in 6 cases and slightly negative in 1 case before revision, but after revision phase shift became significantly negative in all cases. Otoacoustic emissions noninvasively reflect cerebrospinal fluid shunt function and are impacted by valve-opening pressure adjustments. Otoacoustic emissions consistently diagnosed shunt malfunction and

Exhaust gas bypass valve control for thermoelectric generator

DOEpatents

Reynolds, Michael G; Yang, Jihui; Meisner, Greogry P.; Stabler, Francis R.; De Bock, Hendrik Pieter Jacobus; Anderson, Todd Alan

2012-09-04

A method of controlling engine exhaust flow through at least one of an exhaust bypass and a thermoelectric device via a bypass valve is provided. The method includes: determining a mass flow of exhaust exiting an engine; determining a desired exhaust pressure based on the mass flow of exhaust; comparing the desired exhaust pressure to a determined exhaust pressure; and determining a bypass valve control value based on the comparing, wherein the bypass valve control value is used to control the bypass valve.

Cracking a tricuspid perimount bioprosthesis to optimize a second transcatheter sapien valve-in-valve placement.

PubMed

Brown, Stephen C; Cools, Bjorn; Gewillig, Marc

2016-09-01

Bioprosthetic valves degenerate over time. Transcatheter valve-in-valve procedures have become an attractive alternative to surgery. However, every valve increasingly diminishes the diameter of the valvar orifice. We report a 12-year-old female who had a previous transcatheter tricuspid valve-in-valve procedure; cracking the ring of a Carpentier Edwards Perimount valve by means of an ultrahigh pressure balloon allowed implantation of a further larger percutaneous valve. The advantage of this novel approach permits enlarging the inner valve diameter and may facilitate future interventions and prolong time to surgery. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Simplified pulse reactor for real-time long-term in vitro testing of biological heart valves.

PubMed

Schleicher, Martina; Sammler, Günther; Schmauder, Michael; Fritze, Olaf; Huber, Agnes J; Schenke-Layland, Katja; Ditze, Günter; Stock, Ulrich A

2010-05-01

Long-term function of biological heart valve prostheses (BHV) is limited by structural deterioration leading to failure with associated arterial hypertension. The objective of this work was development of an easy to handle real-time pulse reactor for evaluation of biological and tissue engineered heart valves under different pressures and long-term conditions. The pulse reactor was made of medical grade materials for placement in a 37 degrees C incubator. Heart valves were mounted in a housing disc moving horizontally in culture medium within a cylindrical culture reservoir. The microprocessor-controlled system was driven by pressure resulting in a cardiac-like cycle enabling competent opening and closing of the leaflets with adjustable pulse rates and pressures between 0.25 to 2 Hz and up to 180/80 mmHg, respectively. A custom-made imaging system with an integrated high-speed camera and image processing software allow calculation of effective orifice areas during cardiac cycle. This simple pulse reactor design allows reproducible generation of patient-like pressure conditions and data collection during long-term experiments.

Valve for controlling solids flow

DOEpatents

Feldman, David K.

1980-01-01

A fluidized solids control valve is disclosed that is particularly well adapted for use with a flow of coal or char that includes both large particles and fines. The particles may or may not be fluidized at various times during the operation. The valve includes a tubular body that terminates in a valve seat covered by a normally closed closure plate. The valve body at the seat and the closure plate is provided with aligned longitudinal slots that receive a pivotally supported key plate. The key plate is positionable by an operator in inserted, intermediate and retracted positions respecting the longitudinal slot in the valve body. The key plate normally closes the slot within the closure plate but is shaped and aligned obliquely to the longitudinal slot within the valve body to provide progressively increasing slot openings between the inserted and retracted positions. Transfer members are provided between the operator, key plate and closure plate to move the closure plate into an open position only when the key plate is retracted from the longitudinal slot within the valve body.

Pressure Seal For Frequently Opened Hatch

NASA Technical Reports Server (NTRS)

Kennedy, Steven E.; Kramer, Joel M.

1994-01-01

Pressure-assisted seal for frequently opened hatch includes two sealing rings retained positively so not pulled out during opening. Seal makes contact with hatch well before hatch starts to squeeze rings extending distance over which seal becomes engaged. Improvements include more-secure mounting, redundancy, and better initial sealing action. Also minimizes loss of gas during closure by deflecting inward and closing gap. This action helps differential pressure to force hatch closed.

Development of a Fast Valve for Disruption Mitigation and its Preliminary Application to EAST and HT-7

NASA Astrophysics Data System (ADS)

Zhuang, Huidong; Zhang, Xiaodong

2013-08-01

In large tokamaks, disruption of high current plasma would damage plasma facing component surfaces (PFCs) or other inner components due to high heat load, electromagnetic force load and runaway electrons. It would also influence the subsequent plasma discharge due to production of impurities during disruptions. So the avoidance and mitigation of disruptions is essential for the next generation of tokamaks, such as ITER. Massive gas injection (MGI) is a promising method of disruption mitigation. A new fast valve has been developed successfully on EAST. The valve can be opened in 0.5 ms, and the duration of open state is largely dependent on the gas pressure and capacitor voltage. The throughput of the valve can be adjusted from 0 mbar·L to 700 mbar·L by changing the capacitor voltage and gas pressure. The response time and throughput of the fast valve can meet the requirement of disruption mitigation on EAST. In the last round campaign of EAST and HT-7 in 2010, the fast valve has operated successfully. He and Ar was used for the disruption mitigation on HT-7. By injecting the proper amount of gas, the current quench rate could be slowed down, and the impurities radiation would be greatly improved. In elongated plasmas of EAST discharges, the experimental data is opposite to that which is expected.

Valve technology: A compilation

NASA Technical Reports Server (NTRS)

1971-01-01

A technical compilation on the types, applications and modifications to certain valves is presented. Data cover the following: (1) valves that feature automatic response to stimuli (thermal, electrical, fluid pressure, etc.), (2) modified valves changed by redesign of components to increase initial design effectiveness or give the item versatility beyond its basic design capability, and (3) special purpose valves with limited application as presented, but lending themselves to other uses with minor changes.

Downhole surge valve for earth boring apparatus

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

Lee, D.W.

1990-05-29

This patent describes a boring tool assembly having an underground percussion mole boring tool powered by a working fluid, the tool being driven through the earth by a rigid drill string pushed by a drilling frame, and a downhole valve assembly fixed between the downhole end of the drill string and the too, the improved downhole valve assembly. It comprises: a valve spool having an open first end, a closed second end and a peripheral sidewall, an axial bore extending partly through the valve spool from the open first end; a radial passage adjacent the closed second and of themore » valve spool, the radial passage extending radially from the valve spool axial bore through the valve spool peripheral sidewall; an axial groove in the peripheral sidewall of the valve spool; a valve body having a first end, a second end and a peripheral sidewall, an axial bore extending through the valve body, the valve spool extending through the valve body axial bore so that the second end of the valve body is adjacent the closed second end of the valve spool, the valve spool being axially moveable within the valve body axial bore; an axial slot; a free-floating key element; a valve housing; and seal means.« less

Modeling study of the ABS relay valve

NASA Astrophysics Data System (ADS)

Lei, Ming; Lin, Min; Guo, Bin; Luo, Zai; Xu, Weidong

2011-05-01

The ABS (anti-lock braking system) relay valve is the key component of anti-lock braking system in most commercial vehicles such as trucks, tractor-trailers, etc. In this paper, structure of ABS relay valve and its work theory were analyzed. Then a mathematical model of ABS relay valve, which was investigated by dividing into electronic part, magnetic part, pneumatic part and mechanical part, was set up. The displacement of spools and the response of pressure increasing, holding, releasing of ABS relay valve were simulated and analyzed under conditions of control pressure 500 KPa, braking pressure 600 KPa, atmospheric pressure 100 KPa and air temperature 310 K. Thisarticle provides reliable theory for improving the performance and efficiency of anti-lock braking system of vehicles.

Problem: Heart Valve Regurgitation

MedlinePlus

... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

Problem: Mitral Valve Regurgitation

MedlinePlus

... each time the left ventricle contracts. Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

Pannus Formation Leads to Valve Malfunction in the Tricuspid Position 19 Years after Triple Valve Replacement.

PubMed

Alskaf, Ebraham; McConkey, Hannah; Laskar, Nabila; Kardos, Attila

2016-06-20

The Medtronic ATS Open Pivot mechanical valve has been successfully used in heart valve surgery for more than two decades. We present the case of a patient who, 19 years following a tricuspid valve replacement with an ATS prosthesis as part of a triple valve operation following infective endocarditis, developed severe tricuspid regurgitation due to pannus formation.

Valving for controlling a fluid-driven reciprocating apparatus

DOEpatents

Whitehead, J.C.

1995-06-27

A pair of control valve assemblies is described for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve assembly is switched by a pressure signal depending on the state of its counterpart`s piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow. Each of the valve assemblies uses an intake-exhaust valve and a signal valve with the signal valve of one pump being connected to be pressure responsive to the piston of the opposite cylinder or pump. 15 figs.

Main Oxidizer Valve Design

NASA Technical Reports Server (NTRS)

Addona, Brad; Eddleman, David

2015-01-01

A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

Reduced-impact sliding pressure control valve for pneumatic hammer drill

DOEpatents

Polsky, Yarom [Oak Ridge, TN; Grubelich, Mark C [Albuquerque, NM; Vaughn, Mark R [Albuquerque, NM

2012-05-15

A method and means of minimizing the effect of elastic valve recoil in impact applications, such as percussive drilling, where sliding spool valves used inside the percussive device are subject to poor positioning control due to elastic recoil effects experienced when the valve impacts a stroke limiting surface. The improved valve design reduces the reflected velocity of the valve by using either an energy damping material, or a valve assembly with internal damping built-in, to dissipate the compression stress wave produced during impact.

Flow metering valve

DOEpatents

Blaedel, K.L.

1983-11-03

An apparatus for metering fluids at high pressures of about 20,000 to 60,000 psi is disclosed. The apparatus includes first and second plates which are positioned adjacent each other to form a valve chamber. The plates are made of materials which have substantially equal elastic properties. One plate has a planar surface area, and the other a recessed surface area defined by periphery and central lips. When the two plates are positioned in adjacent contacting relationship, a valve chamber is formed between the planar surface area and the recessed surface area. Fluid is introduced into the chamber and exits therefrom when a deformation occurs at positions where they no longer form a valve seat. This permits the metering of fluids at high pressures and at slow variable rates. Fluid then exits from the chamber until an applied external force becomes large enough to bring the valve seats back into contact.

Flow metering valve

DOEpatents

Blaedel, Kenneth L.

1985-01-01

An apparatus for metering fluids at high pressures of about 20,000 to 60,000 psi is disclosed. The apparatus includes first and second plates which are positioned adjacent each other to form a valve chamber. The plates are made of materials which have substantially equal elastic properties. One plate has a planar surface area, and the other a recessed surface area defined by periphery and central lips. When the two plates are positioned in adjacent contacting relationship, a valve chamber is formed between the planar surface area and the recessed surface area. Fluid is introduced into the chamber and exits therefrom when a deformation occurs at positions where they no longer form a valve seat. This permits the metering of fluids at high pressures and at slow variable rates. Fluid then exits from the chamber until an applied external force becomes large enough to bring the valve seats back into contact.

40 CFR 264.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2014 CFR

2014-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief devices in light liquid...

40 CFR 264.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2011 CFR

2011-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief devices in light liquid...

40 CFR 264.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2012 CFR

2012-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief devices in light liquid...

40 CFR 264.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2013 CFR

2013-07-01

... liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other connectors. (a) Pumps and valves in heavy liquid service, pressure relief devices in light liquid...

The Use of Stepper Motor-Controlled Proportional Valve for Fio2 Calculation in the Ventilator and its Control with Fuzzy Logic.

PubMed

Gölcük, Adem; Güler, İnan

2017-01-01

This article proposes the employment of a proportional valve that can calculate the amount of oxygen in the air to be given to patient in accordance with the amount of FiO 2 which is set from the control menu of the ventilation device. To actualize this, a stepper motor-controlled proportional valve was used. Two counts of valves were employed in order to control the gases with 2 bar pressure that came from both the oxygen and medical air tanks. Oxygen and medical air manometers alongside the pressure regulators were utilized to perform this task. It is a fuzzy-logic-based controller which calculates at what rate the proportional valves will be opened and closed for FiO 2 calculation. Fluidity and pressure of air given by the ventilation device were tested with a FlowMeter while the oxygen level was tested using the electronic lung model. The obtained results from the study revealed that stepper motor controlled proportional valve could be safely used in ventilation devices. In this article, it was indicated that fluidity and pressure control could be carried out with just two counts of proportional valve, which could be done with many solenoid valves, so this reduces the cost of ventilator, electrical power consumed by the ventilator, and the dimension of ventilator.

Hydraulic engine valve actuation system including independent feedback control

DOEpatents

Marriott, Craig D

2013-06-04

A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

Magnetic Check Valve

NASA Technical Reports Server (NTRS)

Morris, Brian G.; Bozeman, Richard J., Jr.

1994-01-01

Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

Thermostatic Valves Containing Silicone-Oil Actuators

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep; Birur, Gajanana C.; Bame, David P.; Karlmann, Paul B.; Prina, Mauro; Young, William; Fisher, Richard

2009-01-01

Flow-splitting and flow-mixing thermally actuated spool valves have been developed for controlling flows of a heat-transfer fluid in a temperature-regulation system aboard the Mars Science Laboratory (MSL) rover. Valves like these could also be useful in terrestrial temperature-regulation systems, including automobile air-conditioning systems and general refrigeration systems. These valves are required to provide smoother actuation over a wider temperature range than the flow-splitting, thermally actuated spool valves used in the Mars Explorer Rover (MER). Also, whereas the MER valves are unstable (tending to oscillate) in certain transition temperature ranges, these valves are required not to oscillate. The MER valves are actuated by thermal expansion of a wax against spring-loaded piston rods (as in common automotive thermostats). The MSL valves contain similar actuators that utilize thermal expansion of a silicone oil, because silicone-oil actuators were found to afford greater and more nearly linear displacements, needed for smoother actuation, over the required wider temperature range. The MSL valves also feature improved spool designs that reflect greater understanding of fluid dynamics, consideration of pressure drops in valves, and a requirement for balancing of pressures in different flow branches.

Apparatus comprising magnetically actuated valves and uses thereof

DOEpatents

Edwards, Thayne L.; Harper, Jason C.

2016-07-12

The present invention, in part, relates to an apparatus having a single-use, normally-closed fluidic valve that is initially maintained in the closed position by a valve element bonded to an adhesive coating. The valve is opened using a magnetic force. The valve element includes a magnetic material or metal. In some examples, the valve is opened by bringing a magnet in proximity to the valve element to provide a magnetic force that delaminates the valve element from the adhesive coating. In particular, the apparatus can be useful for on-chip amplification and/or detection of various targets, including biological targets and any amplifiable targets. Such apparatuses and methods are useful for in-field or real-time detection of targets, especially in limited resource settings.

Operational durability of a giant ER valve for Braille display

NASA Astrophysics Data System (ADS)

Luning, Xu; Han, Li; Yufei, Li; Shen, Rong; Kunquan, Lu

2017-05-01

The compact configuration of giant ER (electrorheological) valves provides the possibility of realizing a full-page Braille display. The operational durability of ER valves is a key issue in fulfilling a Braille display. A giant ER valve was used to investigate the variations in pressure drops and critical pressure drops of the valves over a long period under some typical operational parameters. The results indicate that neither the pressure drops nor critical pressure drops of giant ER valves show apparent deterioration over a long period. Without ER fluid exchange, a blockage appears in the channel of the valve because the ER structures induced by an external electric field cannot be broken by the Brownian motion of hydraulic oil molecules when the external electric field is removed. Forcing ER fluid flow is an effective and necessary method to keep the channel of the valve unblocked. Thus the operational durability of the valve using giant ER fluids is able to meet the demands of Braille display.

Method and system for measuring gate valve clearances and seating force

DOEpatents

Casada, Donald A.; Haynes, Howard D.; Moyers, John C.; Stewart, Brian K.

1996-01-01

Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner.

A low power, on demand electrothermal valve for wireless drug delivery applications

PubMed Central

Li, Po-Ying; Givrad, Tina K.; Sheybani, Roya; Holschneider, Daniel P.; Maarek, Jean-Michel I.

2014-01-01

We present a low power, on demand Parylene MEMS electrothermal valve. A novel Ω-shaped thermal resistive element requires low power (~mW) and enables rapid valve opening (~ms). Using both finite element analysis and valve opening experiments, a robust resistive element design for improved valve opening performance in water was obtained. In addition, a thermistor, as an inrush current limiter, was added into the valve circuit to provide variable current ramping. Wireless activation of the valve using RF inductive power transfer was demonstrated. PMID:20024057

Research on the water hammer protection of the long distance water supply project with the combined action of the air vessel and over-pressure relief valve

NASA Astrophysics Data System (ADS)

Li, D. D.; Jiang, J.; Zhao, Z.; Yi, W. S.; Lan, G.

2013-12-01

We take a concrete pumping station as an example in this paper. Through the calculation of water hammer protection with a specific pumping station water supply project, and the analysis of the principle, mathematical models and boundary conditions of air vessel and over-pressure relief valve we show that the air vessel can protect the water conveyance system and reduce the transient pressure damage due to various causes. Over-pressure relief valve can effectively reduce the water hammer because the water column re-bridge suddenly stops the pump and prevents pipeline burst. The paper indicates that the combination set of air vessel and over-pressure relief valve can greatly reduce the quantity of the air valve and can eliminate the water hammer phenomenon in the pipeline system due to the vaporization and water column separation and re-bridge. The conclusion could provide a reference for the water hammer protection of long-distance water supply system.

Method and system for measuring gate valve clearances and seating force

DOEpatents

Casada, D.A.; Haynes, H.D.; Moyers, J.C.; Stewart, B.K.

1996-01-30

Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner. 8 figs.

Effect of vertebral shell on injection pressure and intravertebral pressure in vertebroplasty.

PubMed

Baroud, Gamal; Vant, Christianne; Giannitsios, Demetri; Bohner, Marc; Steffen, Thomas

2005-01-01

An experimental biomechanical study conducted on osteoporotic cadaveric vertebrae. 1) To measure the intravertebral shell pressure and injection pressure; and 2) to determine the effect of the vertebral shell on the intravertebral shell pressure and on the injection pressure. Forces that govern cement flow are an essential component of the cement injection process in vertebroplasty. The vertebral shell may play a significant role in confining the flow of cement in the vertebral body and thereby affecting the intravertebral pressure and injection pressure. A small fenestration was created in the left lateral vertebral shell of 14 vertebrae. A valve to open and close the fenestration and a sensor to measure the intravertebral pressure were attached to the opening. A closed fenestration simulated an intact shell, whereas an open fenestration represented a vented shell. Injection pressure and intravertebral pressure at the shell were recorded during a controlled injection. A closed fenestration resulted in a significant increase in the intravertebral pressure at the shell. During the injection, the shell pressure increased on average to approximately 3.54 +/- 2.91 kPa. Conversely, an open fenestration resulted in an instant relaxation of the shell pressure to the ambient pressure of 0 kPa. Additionally, the injection pressure was approximately 97 times higher than the shell pressure. The presence of vertebral shell seems to be important for intravertebral pressure. However, the intravertebral shell pressure adds very little to the injection pressure.

Cavitation guide for control valves

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

Tullis, J.P.

1993-04-01

This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines sixmore » cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.« less

Engine Valve Actuation For Combustion Enhancement

DOEpatents

Reitz, Rolf Deneys; Rutland, Christopher J.; Jhavar, Rahul

2004-05-18

A combustion chamber valve, such as an intake valve or an exhaust valve, is briefly opened during the compression and/or power strokes of a 4-stroke combustion cycle in an internal combustion engine (in particular, a diesel or CI engine). The brief opening may (1) enhance mixing withing the combustion chamber, allowing more complete oxidation of particulates to decrease engine emissions; and/or may (2) delay ignition until a more desirable time, potentially allowing a means of timing ignition in otherwise difficult-to-control conditions, e.g., in HCCI (Homogeneous Charge Compression Ignition) conditions.

Engine valve actuation for combustion enhancement

DOEpatents

Reitz, Rolf Deneys [Madison, WI; Rutland, Christopher J [Madison, WI; Jhavar, Rahul [Madison, WI

2008-03-04

A combustion chamber valve, such as an intake valve or an exhaust valve, is briefly opened during the compression and/or power strokes of a 4-strokes combustion cycle in an internal combustion engine (in particular, a diesel or CI engine). The brief opening may (1) enhance mixing withing the combustion chamber, allowing more complete oxidation of particulates to decrease engine emissions; and/or may (2) delay ignition until a more desirable time, potentially allowing a means of timing ignition in otherwise difficult-to-control conditions, e.g., in HCCI (Homogeneous Charge Compression Ignition) conditions.

Effect of pressure pulses at the interface valve on the stability of second dimension columns in online comprehensive two-dimensional liquid chromatography.

PubMed

Talus, Eric S; Witt, Klaus E; Stoll, Dwight R

2015-01-23

Users of online comprehensive two-dimensional liquid chromatography (LCxLC) frequently acknowledge that the mechanical instability of HPLC columns installed in these systems, particularly in the second dimension, is a significant impediment to its use. Such instability is not surprising given the strenuous operating environment to which these columns are subjected, including the large number (thousands per day) of fast and large pressure pulses resulting from interface valve switches (on the timescale of tens of milliseconds) associated with very fast second dimension separations. There appear to be no published reports of systematic studies of the relationship between second dimension column lifetime and any of these variables. In this study we focused on the relationship between the lifetimes of commercially available columns and the pressure pulses observed at the inlet of the second dimension column that occur during the switching of the valve that interfaces the two dimensions of a LCxLC system. We find that the magnitude of the pressure drop at the inlet of the second dimension column during the valve switch, which may vary between 10 and 95% of the column inlet pressure, is dependent on valve switching speed and design, and has a dramatic impact on column lifetime. In the worst case, columns fail within the first few hours of use in an LCxLC system. In the best case, using a valve that exhibits much smaller pressure pulses, the same columns exhibit much improved lifetimes and have been used continuously under LCxLC conditions for several days with no degradation in performance. This result represents a first step in understanding the factors that affect second dimension column lifetime, and will significantly improve the usability of the LCxLC technique in general. Copyright © 2014 Elsevier B.V. All rights reserved.

Fluid Dynamic Characterization of a Polymeric Heart Valve Prototype (Poli-Valve) tested under Continuous and Pulsatile Flow Conditions

PubMed Central

De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D.; Costantino, Maria Laura

2016-01-01

Introduction Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy, the latter display better fluid dynamic behaviour but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the haemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of two groups of newly developed supra-annular tri-leaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. Methods Two types of Poli-Valves made of SBC differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. An ad - hoc designed pulse duplicator allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the valve’s behaviour. Results Both types Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by ISO 5840 Standard. Results were compared with five mechanical heart valves (MHVs) and five tissue heart valves (THVs), currently available on the market. Conclusion Based on these results, polymeric heart valves based on styrenic block copolymers, as Poli-Valves are, can be considered as promising alternative for heart valve replacement in near future. PMID:26689146

Fluid dynamic characterization of a polymeric heart valve prototype (Poli-Valve) tested under continuous and pulsatile flow conditions.

PubMed

De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D; Costantino, Maria Laura

2015-11-01

Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy; the latter display better fluid dynamic behavior but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the hemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of 2 groups of newly developed supra-annular, trileaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. 2 types of Poli-Valves made of SBC and differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. A pulse duplicator designed ad hoc allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the behavior of the valve. Both types of Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by the ISO 5840 Standard. Results were compared with 5 mechanical heart valves (MHVs) and 5 tissue heart valves (THVs), currently available on the market. Based on these results, PHVs based on styrenic block copolymers, as are Poli-Valves, can be considered a promising alternative for heart valve replacement in the near future.

Valve for fuel pin loading system

DOEpatents

Christiansen, David W.

1985-01-01

A cyclone valve surrounds a wall opening through which cladding is projected. An axial valve inlet surrounds the cladding. Air is drawn through the inlet by a cyclone stream within the valve. An inflatable seal is included to physically engage a fuel pin subassembly during loading of fuel pellets.

Tricuspid valve and percutaneous approach: No longer the forgotten valve!

PubMed

Bouleti, Claire; Juliard, Jean-Michel; Himbert, Dominique; Iung, Bernard; Brochet, Eric; Urena, Marina; Dilly, Marie-Pierre; Ou, Phalla; Nataf, Patrick; Vahanian, Alec

2016-01-01

Tricuspid valve disease is mainly represented by tricuspid regurgitation (TR), which is a predictor of poor outcome. TR is usually secondary, caused by right ventricle pressure or volume overload, the leading cause being left-sided heart valve diseases. Tricuspid surgery for severe TR is recommended during left valve surgery, and consists of either a valve replacement or, most often, a tricuspid repair with or without prosthetic annuloplasty. When TR persists or worsens after left valvular surgery, redo isolated tricuspid surgery is associated with high mortality. In addition, a sizeable proportion of patients present with tricuspid surgery deterioration over time, and need a reintervention, which is associated with high morbi-mortality rates. In this context, and given the recent major breakthrough in the percutaneous treatment of aortic and mitral valve diseases, the tricuspid valve appears an appealing challenge, although it raises specific issues. The first applications of transcatheter techniques for tricuspid valve disease were valve-in-valve and valve-in-ring implantation for degenerated bioprosthesis or ring annuloplasty. Some concerns remain regarding prosthesis sizing, rapid ventricular pacing and the best approach, but these procedures appear to be safe and effective. More recently, bicuspidization using a transcatheter approach for the treatment of native tricuspid valve has been published, in two patients. Finally, other devices are in preclinical development. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Fuel injection of coal slurry using vortex nozzles and valves

DOEpatents

Holmes, Allen B.

1989-01-01

Injection of atomized coal slurry fuel into an engine combustion chamber is achieved at relatively low pressures by means of a vortex swirl nozzle. The outlet opening of the vortex nozzle is considerably larger than conventional nozzle outlets, thereby eliminating major sources of failure due to clogging by contaminants in the fuel. Control fluid, such as air, may be used to impart vorticity to the slurry and/or purge the nozzle of contaminants during the times between measured slurry charges. The measured slurry charges may be produced by a diaphragm pump or by vortex valves controlled by a separate control fluid. Fluidic circuitry, employing vortex valves to alternatively block and pass cool slurry fuel flow, is disclosed.

Hydrodynamics of the Certas™ programmable valve for the treatment of hydrocephalus

PubMed Central

2012-01-01

Background The new Certas™ shunt for the treatment of hydrocephalus has seven standard pressure settings that according to the manufacturer range from 36 to 238 mmH2O, and an additional “Virtual Off” setting with an opening pressure >400 mmH2O. Information on actual pressure response and reliability of shunt performance is important in clinical application, especially the “Virtual Off” setting as a non-surgical replacement for shunt ligation. The objective of this study was to evaluate the in-vitro hydrodynamic performance of the Certas™ shunt. Methods Six new Certas™ shunts with proximal and distal catheters were tested with an automated, computerized test system that raised the pressure from zero to a maximum pressure and back to zero at each valve setting. Opening pressure and flow resistance were determined. Results For settings 1–7 the measured opening pressure range was 26 to 247 mmH2O, and the mean change in opening pressure for a one-step adjustment was between 33 and 38 mmH2O. For setting 8 (“Virtual Off”) the measured mean opening pressure was 494 ± 34 mmH2O (range 451 to 556 mmH2O). The mean outflow resistance was 7.0 mmHg/ml/min (outflow conductance 17.9 μl/s/kPa). Conclusions The six shunts had similar characteristics and closely matched the manufacturer’s specifications for opening pressure at settings 1–7. The opening pressure for the “Virtual Off” setting was nearly 500 mmH2O, which is 100 mmH2O higher than the manufacturer’s specification of “>400” and should be functionally off for most patients with communicating hydrocephalus. Clinical studies are needed to evaluate if the CSF dynamic profile persists after implantation in patients. PMID:22643114

46 CFR 95.15-50 - Lockout valves.

Code of Federal Regulations, 2012 CFR

2012-10-01

... must make it obvious whether the valve is open or closed. (d) A valve is considered a lockout valve if... be approved by the Commandant as part of the installed system. [USCG-2006-24797, 77 FR 33878, Jun. 7...

46 CFR 76.15-50 - Lockout valves.

Code of Federal Regulations, 2012 CFR

2012-10-01

... make it obvious whether the valve is open or closed. (d) A valve is considered a lockout valve if it... approved by the Commandant as part of the installed system. [USCG-2006-24797, 77 FR 33876, Jun. 7, 2012] ...

40 CFR 60.482-8a - Standards: Pumps, valves, and connectors in heavy liquid service and pressure relief devices in...

Code of Federal Regulations, 2012 CFR

2012-07-01

... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. 60... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. (a... at pumps, valves, and connectors in heavy liquid service and pressure relief devices in light liquid...

40 CFR 60.482-8a - Standards: Pumps, valves, and connectors in heavy liquid service and pressure relief devices in...

Code of Federal Regulations, 2013 CFR

2013-07-01

... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. 60... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. (a... at pumps, valves, and connectors in heavy liquid service and pressure relief devices in light liquid...

40 CFR 60.482-8a - Standards: Pumps, valves, and connectors in heavy liquid service and pressure relief devices in...

Code of Federal Regulations, 2011 CFR

2011-07-01

... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. 60... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. (a... at pumps, valves, and connectors in heavy liquid service and pressure relief devices in light liquid...

40 CFR 60.482-8a - Standards: Pumps, valves, and connectors in heavy liquid service and pressure relief devices in...

Code of Federal Regulations, 2014 CFR

2014-07-01

... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. 60... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. (a... at pumps, valves, and connectors in heavy liquid service and pressure relief devices in light liquid...

40 CFR 60.482-8a - Standards: Pumps, valves, and connectors in heavy liquid service and pressure relief devices in...

Code of Federal Regulations, 2010 CFR

2010-07-01

... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. 60... connectors in heavy liquid service and pressure relief devices in light liquid or heavy liquid service. (a... at pumps, valves, and connectors in heavy liquid service and pressure relief devices in light liquid...

Intelligent Flow Control Valve

NASA Technical Reports Server (NTRS)

Kelley, Anthony R (Inventor)

2015-01-01

The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

Multi-port valve assembly

DOEpatents

Guggenheim, S. Frederic

1986-01-01

A multi-port fluid valve apparatus is used to control the flow of fluids through a plurality of valves and includes a web, which preferably is a stainless steel endless belt. The belt has an aperture therethrough and is progressed, under motor drive and control, so that its aperture is moved from one valve mechanism to another. Each of the valve mechanisms comprises a pair of valve blocks which are held in fluid-tight relationship against the belt. Each valve block consists of a block having a bore through which the fluid flows, a first seal surrounding the bore and a second seal surrounding the first seal, with the distance between the first and second seals being greater than the size of the belt aperture. In order to open a valve, the motor progresses the belt aperture to where it is aligned with the two bores of a pair of valve blocks, such alignment permitting a flow of the fluid through the valve. The valve is closed by movement of the belt aperture and its replacement, within the pair of valve blocks, by a solid portion of the belt.

Whitey SCHe Ball Valves Provide Test Port Isolation

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

MISKA, C.R.

2000-09-15

These valves are 1/4 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as normally closed isolation valves for test ports in the SCHe System between the gage root valve and the pressure indicator.

Fault Study of Valve Based on Test Analysis and Comparison

NASA Astrophysics Data System (ADS)

Cheng, Li; Yang, Wukui; Liang, Tao; Xu, Yu; Chen, Chao

2017-10-01

The valve of a certain type of small engine often has the fault phenomenon of abnormal vibration noise and can’t close under the specified pressure, which may cause the engine automatic stop because of valve incomplete close leading to fuel leakage during test and startup on the bench. By test study compared to imported valve with the same use function and test condition valve, and put forward the thinking of improving valve structure, compared no-improved valve to improved valve by adopting Fluent field simulation software. As a result, improved valve can restore close pressure of valve, restrain abnormal vibration noise phenomenon, and effectively compensate compression value of spring because of steel ball contacting position downward with valve casing.

Design and operation of a fast electromagnetic inductive massive gas injection valve for NSTX-U

NASA Astrophysics Data System (ADS)

Raman, R.; Jarboe, T. R.; Nelson, B. A.; Gerhardt, S. P.; Lay, W.-S.; Plunkett, G. J.

2014-11-01

Results from the operation of an electromagnetic valve, that does not incorporate ferromagnetic materials, are presented. Image currents induced on a conducting disc placed near a pancake solenoid cause it to move away from the solenoid and open the vacuum seal. A new and important design feature is the use of Lip Seals for the sliding piston. The pressure rise in the test chamber is measured directly using a fast time response Baratron gauge. The valve injects over 200 Torr l of nitrogen in less than 3 ms, which remains unchanged at moderate magnetic fields.

Design and operation of a fast electromagnetic inductive massive gas injection valve for NSTX-U.

PubMed

Raman, R; Jarboe, T R; Nelson, B A; Gerhardt, S P; Lay, W-S; Plunkett, G J

2014-11-01

Results from the operation of an electromagnetic valve, that does not incorporate ferromagnetic materials, are presented. Image currents induced on a conducting disc placed near a pancake solenoid cause it to move away from the solenoid and open the vacuum seal. A new and important design feature is the use of Lip Seals for the sliding piston. The pressure rise in the test chamber is measured directly using a fast time response Baratron gauge. The valve injects over 200 Torr l of nitrogen in less than 3 ms, which remains unchanged at moderate magnetic fields.

Noninvasive estimation of transmitral pressure drop across the normal mitral valve in humans: importance of convective and inertial forces during left ventricular filling

NASA Technical Reports Server (NTRS)

Firstenberg, M. S.; Vandervoort, P. M.; Greenberg, N. L.; Smedira, N. G.; McCarthy, P. M.; Garcia, M. J.; Thomas, J. D.

2000-01-01

OBJECTIVES: We hypothesized that color M-mode (CMM) images could be used to solve the Euler equation, yielding regional pressure gradients along the scanline, which could then be integrated to yield the unsteady Bernoulli equation and estimate noninvasively both the convective and inertial components of the transmitral pressure difference. BACKGROUND: Pulsed and continuous wave Doppler velocity measurements are routinely used clinically to assess severity of stenotic and regurgitant valves. However, only the convective component of the pressure gradient is measured, thereby neglecting the contribution of inertial forces, which may be significant, particularly for nonstenotic valves. Color M-mode provides a spatiotemporal representation of flow across the mitral valve. METHODS: In eight patients undergoing coronary artery bypass grafting, high-fidelity left atrial and ventricular pressure measurements were obtained synchronously with transmitral CMM digital recordings. The instantaneous diastolic transmitral pressure difference was computed from the M-mode spatiotemporal velocity distribution using the unsteady flow form of the Bernoulli equation and was compared to the catheter measurements. RESULTS: From 56 beats in 16 hemodynamic stages, inclusion of the inertial term ([deltapI]max = 1.78+/-1.30 mm Hg) in the noninvasive pressure difference calculation significantly increased the temporal correlation with catheter-based measurement (r = 0.35+/-0.24 vs. 0.81+/-0.15, p< 0.0001). It also allowed an accurate approximation of the peak pressure difference ([deltapc+I]max = 0.95 [delta(p)cathh]max + 0.24, r = 0.96, p<0.001, error = 0.08+/-0.54 mm Hg). CONCLUSIONS: Inertial forces are significant components of the maximal pressure drop across the normal mitral valve. These can be accurately estimated noninvasively using CMM recordings of transmitral flow, which should improve the understanding of diastolic filling and function of the heart.

Evaluation of anticipatory signal to steam generator pressure control program for 700 MWe Indian pressurized heavy water reactor

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

Pahari, S.; Hajela, S.; Rammohan, H. P.

2012-07-01

700 MWe Indian Pressurized Heavy Water Reactor (IPHWR) is horizontal channel type reactor with partial boiling at channel outlet. Due to boiling, it has a large volume of vapor present in the primary loops. It has two primary loops connected with the help of pressurizer surge line. The pressurizer has a large capacity and is partly filled by liquid and partly by vapor. Large vapor volume improves compressibility of the system. During turbine trip or load rejection, pressure builds up in Steam Generator (SG). This leads to pressurization of Primary Heat Transport System (PHTS). To control pressurization of SG andmore » PHTS, around 70% of the steam generated in SG is dumped into the condenser by opening Condenser Steam Dump Valves (CSDVs) and rest of the steam is released to the atmosphere by opening Atmospheric Steam Discharge Valves (ASDVs) immediately after sensing the event. This is accomplished by adding anticipatory signal to the output of SG pressure controller. Anticipatory signal is proportional to the thermal power of reactor and the proportionality constant is set so that SG pressure controller's output jacks up to ASDV opening range when operating at 100% FP. To simulate this behavior for 700 MWe IPHWR, Primary and secondary heat transport system is modeled. SG pressure control and other process control program have also been modeled to capture overall plant dynamics. Analysis has been carried out with 3-D neutron kinetics coupled thermal hydraulic computer code ATMIKA.T to evaluate the effect of the anticipatory signal on PHT pressure and over all plant dynamics during turbine trip in 700 MWe IPHWR. This paper brings out the results of the analysis with and without considering anticipatory signal in SG pressure control program during turbine trip. (authors)« less

A Lifting Ball Valve for cryogenic fluid applications

NASA Astrophysics Data System (ADS)

Cardin, Joseph M.; Reinicke, Robert H.; Bruneau, Stephen D.

1993-11-01

Marotta Scientific Controls, Inc. has designed a Lifting Ball Valve (LBV) capable of both flow modulation and tight shutoff for cryogenic and other applications. The LBV features a thin-walled visor valving element that lifts off the seal with near axial motion before rotating completely out of the flow path. This is accomplished with a simple, robust mechanism that minimizes cost and weight. Conventional spherical rotating seats ar plagued by leakage due to 'scuffing' as the seal and seat slide against one another while opening. Cryogenic valves, which typically utilize plastic seals, are particularly susceptible to this type of damage. The seat in the LBV lifts off the seal without 'scuffing' making it immune to this failure mode. In addition, the LBV lifting mechanism is capable of applying the very high seating loads required to seal at cryogenic temperatures. These features make the LBV ideally suited for cryogenic valve applications. Another major feature of the LBV is the fact that the visor rotates completely out of the flow path. This allows for a smaller, lighter valve for a given flow capacity, especially for line sizes above one inch. The LBV is operated by a highly integrated 'wetted' DC brushless motor. The motor rotor is 'wetted' ion that it is immersed in the fluid. To ensure compatibility, the motor rotor is encased in a thin-walled CRES weldment. The motor stator is outside the fluid containment weldment and therefore is not in direct contact with the fluid. To preclude the potential for external leakage there are no static or dynamic seals or bellows across the pressure boundary. The power required to do the work of operating the valving mechanism is transmitted across the pressure boundary by electromagnetic interaction between the motor rotor and the stator. Commutation of the motor is accomplished using the output of a special 'wetted' resolver. This paper describes the design, operation, and element testing of the LBV.

40 CFR 264.1058 - Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Pumps and valves in heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and other... heavy liquid service, pressure relief devices in light liquid or heavy liquid service, and flanges and...

Stemless Ball Valve

NASA Technical Reports Server (NTRS)

Burgess, Robert K.; Yakos, David; Walthall, Bryan

2012-01-01

This invention utilizes a new method of opening and closing a ball valve. Instead of rotating the ball with a perpendicular stem (as is the case with standard ball valves), the ball is rotated around a fixed axis by two guide pins. This innovation eliminates the leak point that is present in all standard ball valves due to the penetration of an actuation stem through the valve body. The VOST (Venturi Off-Set-Technology) valve has been developed for commercial applications. The standard version of the valve consists of an off-set venturi flow path through the valve. This path is split at the narrowest portion of the venturi, allowing the section upstream from the venturi to be rotated. As this rotation takes place, the venturi becomes restricted as one face rotates with respect to the other, eventually closing off the flow path. A spring-loaded seal made of resilient material is embedded in the upstream face of the valve, making a leak-proof seal between the faces; thus a valve is formed. The spring-loaded lip seal is the only seal that can provide a class six, or bubble-tight, seal against the opposite face of the valve. Tearing action of the seal by high-velocity gas on this early design required relocation of the seal to the downstream face of the valve. In the stemless embodiment of this valve, inner and outer magnetic cartridges are employed to transfer mechanical torque from the outside of the valve to the inside without the use of a stem. This eliminates the leak path caused by the valve stems in standard valves because the stems penetrate through the bodies of these valves.

[Normal pressure hydrocephalus: prognostic value of height in patients treated with an identical shunt system].

PubMed

Aguas, Jesús; Rodrigo, Victor; Estupiñan, Francisco; Nogues, Pere; Villalba, Gloria; Villagrasa, Javier; Caral, Luis

2013-01-01

Normal pressure hydrocephalus (NPH) is a clinical entity frequently managed by means of a cerebrospinal fluid shunt. Hydrodynamic hypotheses consider hydrostatic pressure (as well as height) a very important variable for shunt system function. However, we did not find empirical studies supporting the influence of height on clinical response in the literature. Our objective was to study the prognostic value of height, as a variable related to hydrostatic pressure, when an identical shunt system is used. A prospective series of 61 idiopathic NPH cases was analyzed. All cases were shunted by means of a ventricle-peritoneal system with a 100mmH2O opening pressure valve. Anthropometric, clinical, radiological and pressure variables were registered, as well as delay for treatment, improvement and complications. 78.7% of cases improved after shunting. This group of patients was significantly taller (P=.005) than the group without response (median value 165cm versus 152cm). There was also a significant correlation between height and ventricular size decrease after the shunt. In our series opening valve pressure was a constant (100mmHg) and we could consequently focus on the effect of hydrostatic pressure (height). Moreover, we found a positive predictive value for taller patients, probably because we had selected an opening pressure especially suitable for them. Current gravitational valve shunt systems also recommend considering patient height when customising the system. Our study empirically supports this idea. Copyright © 2012 Sociedad Española de Neurocirugía. Published by Elsevier España. All rights reserved.

Fast valve based on double-layer eddy-current repulsion for disruption mitigation in Experimental Advanced Superconducting Tokamak.

PubMed

Zhuang, H D; Zhang, X D

2015-05-01

A fast valve based on the double-layer eddy-current repulsion mechanism has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to a double-layer eddy-current coil, a preload system was added to improve the security of the valve, whereby the valve opens more quickly and the open-valve time becomes shorter, making it much safer than before. In this contribution, testing platforms, open-valve characteristics, and throughput of the fast valve are discussed. Tests revealed that by choosing appropriate parameters the valve opened within 0.15 ms, and open-valve times were no longer than 2 ms. By adjusting working parameter values, the maximum number of particles injected during this open-valve time was estimated at 7 × 10(22). The fast valve will become a useful tool to further explore disruption mitigation experiments on EAST in 2015.

Mixed mode fuel injector with individually moveable needle valve members

DOEpatents

Stewart, Chris; Chockley, Scott A.; Ibrahim, Daniel R.; Lawrence, Keith; Tomaseki, Jay; Azam, Junru H.; Tian, Steven Ye; Shafer, Scott F.

2004-08-03

A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set controlled respectively, by first and second needle valve members. One of the needle valve members moves to an open position while the other needle valve member remains stationary for a homogeneous charge injection event. The former needle valve member stays stationary while the other needle valve member moves to an open position for a conventional injection event. One of the needle valve members is at least partially positioned in the other needle valve member. Thus, the injector can perform homogeneous charge injection events, conventional injection events, or even a mixed mode having both types of injection events in a single engine cycle.

Functional Heart Valve Scaffolds Obtained by Complete Decellularization of Porcine Aortic Roots in a Novel Differential Pressure Gradient Perfusion System

PubMed Central

Sierad, Leslie Neil; Shaw, Eliza Laine; Bina, Alexander; Brazile, Bryn; Rierson, Nicholas; Patnaik, Sourav S.; Kennamer, Allison; Odum, Rebekah; Cotoi, Ovidiu; Terezia, Preda; Branzaniuc, Klara; Smallwood, Harrison; Deac, Radu; Egyed, Imre; Pavai, Zoltan; Szanto, Annamaria; Harceaga, Lucian; Suciu, Horatiu; Raicea, Victor; Olah, Peter; Simionescu, Agneta; Liao, Jun; Movileanu, Ionela

2015-01-01

There is a great need for living valve replacements for patients of all ages. Such constructs could be built by tissue engineering, with perspective of the unique structure and biology of the aortic root. The aortic valve root is composed of several different tissues, and careful structural and functional consideration has to be given to each segment and component. Previous work has shown that immersion techniques are inadequate for whole-root decellularization, with the aortic wall segment being particularly resistant to decellularization. The aim of this study was to develop a differential pressure gradient perfusion system capable of being rigorous enough to decellularize the aortic root wall while gentle enough to preserve the integrity of the cusps. Fresh porcine aortic roots have been subjected to various regimens of perfusion decellularization using detergents and enzymes and results compared to immersion decellularized roots. Success criteria for evaluation of each root segment (cusp, muscle, sinus, wall) for decellularization completeness, tissue integrity, and valve functionality were defined using complementary methods of cell analysis (histology with nuclear and matrix stains and DNA analysis), biomechanics (biaxial and bending tests), and physiologic heart valve bioreactor testing (with advanced image analysis of open–close cycles and geometric orifice area measurement). Fully acellular porcine roots treated with the optimized method exhibited preserved macroscopic structures and microscopic matrix components, which translated into conserved anisotropic mechanical properties, including bending and excellent valve functionality when tested in aortic flow and pressure conditions. This study highlighted the importance of (1) adapting decellularization methods to specific target tissues, (2) combining several methods of cell analysis compared to relying solely on histology, (3) developing relevant valve-specific mechanical tests, and (4) in vitro testing

The Effect of Valve Cooling upon Maximum Permissible Engine Output as Limited by Knock

NASA Technical Reports Server (NTRS)

Munger, Maurice; Wilsted, H D; Mulcahy, B A

1942-01-01

A Wright GR-1820-G200 cylinder was tested over a wide range of fuel-air ratios at maximum permissible power output as limited by knock with three different degrees of valve cooling. The valves used were stock valves (solid inlet valve and hollow sodium-cooled exhaust valve), hollow valves with no coolant, and hollow valves with flowing water as a coolant. Curves showing the variation in maximum permissible values of inlet-air pressure, indicated mean effective pressure, cylinder charge, and indicated specific fuel consumption with change in fuel-air ratio and valve cooling are shown. The use of valves cooled by a stream of water passing through their hollow interiors permitted indicated mean effective pressures 10 percent higher than the mean effective pressures permissible with stock valves when the engine was operated with fuel-air ratios from 0.055 to 0.065. Operation of the engine with lean mixtures with uncooled hollow valves resulted in power output below the output obtained with the stock valves. The data show an increase in maximum permissible indicated mean effective pressure due to cooling the valves, which averages only 2.1 percent with fuel-air ratios from 0.075 to 0.105.

Streamline coal slurry letdown valve

DOEpatents

Platt, Robert J.; Shadbolt, Edward A.

1983-01-01

A streamlined coal slurry letdown valve is featured which has a two-piece throat comprised of a seat and seat retainer. The two-piece design allows for easy assembly and disassembly of the valve. A novel cage holds the two-piece throat together during the high pressure letdown. The coal slurry letdown valve has long operating life as a result of its streamlined and erosion-resistance surfaces.

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.

A thin film nitinol heart valve.