Abstract: A check valve for connection in a fuel tank filler tube. The valve has a tubular body with a plurality of radially inwardly extending projections on the inner surface of the tubular body or mounting adaptor. A valve seat is disposed downstream of the ribs, and an aperture is formed in the side of the tubular body. When the end of a siphoning hose is inserted into the check valve, the projections deflect the hose through the aperture to facilitate further insertion of the hose into the tank.

Abstract: A check valve having a piston-like ball or stopper a pre-determined distance from the valve seat so that the ball or stopper seats against the valve seat only under backflow pressure.

Abstract: A check valve for use in pump of hydraulic cylinder comprises a check valve including a tubular member disposed therein and having a sheath member received therein, a pump including a chamber provided in an output pipe thereof for receiving the check valve, wherein the tubular member is constructed in the form of a hollow cylinder and includes a sealing sleeve fitted therearound, and includes an oil seal mounted on the front end thereof for the engagement with a hollow screw element in the chamber; the sheath member is comprised of a hollow cap member, a first spring element, a ball, a hollow disc element which are placed into the tubular member in turn, and a second spring element. By using the disc element and the second spring element, the tubular member may be fixed in the chamber, and by way of the screw element, the tubular member is enclosed in the chamber.

Abstract: A combination check valve and relief valve has a valve body with an inlet, an outlet, and a valve chamber operatively interposed between the inlet and outlet. A check valve may be integrated with the relief valve and therefore simplify a hydraulic system. The valve includes a relief valve member which is within the valve chamber. The valve also includes a resilient member with a first end and a second end. The first end of the resilient member operatively engages the relief valve member. The valve includes a setting member pressure-fit within the valve chamber to operatively engage the second end of the resilient member. The resilient member is resiliently biased between the setting member and the relief valve member to bias the relief valve member against a relief valve seat, whereby, when pressurized fluid communicates with the inlet, the resilient member is compressed, and the relief valve member disengages its seat to enable the fluid to pass through to the outlet.

Abstract: The invention relates to a load-pressure-controlled fees flow regulator (1) for adjusting the feed volume of an adjustable hydraulic pump (2) which feeds in a working line (3). The load-pressure-controlled feed flow regulator (1) has an adjusting device (5) for adjusting the feed volume of the hydraulic pump (2). The adjusting device (5) is acted on with an adjusting pressure in order to adjust the feed volume of the hydraulic pump (2). The level of the adjusting pressure is generated by an adjusting pressure regulating device (17). In addition to the adjusting pressure regulating device (17), the fees flow regulator (1) has a damping device (30).

Abstract: An activatable pump is provided. The pump includes a piston in slideable communication with an inner surface of a cylinder, which has a first end and a second end. A first control valve and a second control valve are in physical communication with the first end of the cylinder. The first control valve and the second control valve are in fluid communication with the piston. Either the first control valve or the second control valve is not a check valve. A first check valve and a second check valve are in physical communication with the second end of the cylinder. The first check valve and the second check valve are in fluid communication with the piston. A pressure controller communicates with the piston to control an amount of force by or on the piston. A method and an energy recovery apparatus are also provided.

Abstract: Disclosed is a check valve (5) that is screwed into a threaded bore (1) of a housing (2) of a hydraulic subassembly between a first pressure side (26) and a second pressure side (27) by means of an external thread (11) which is disposed in a first cylinder section (8) of a cylindrical valve housing (6) of the check valve (5). A passage duct (39) which allows a hydraulic fluid to flow between the sidewall of the threaded bore (1) and a first removed portion (16) of the surface area (10) of the cylindrical valve housing (6) is embodied in at least one angular segment (a1, a2, and a3) of the valve housing (6).

Abstract: A regulation valve has: a cylinder that has an inlet port at one end side thereof to introduce the fuel thereinto, and a relief port opening on a side face thereof; a piston that is reciprocatably inserted in the cylinder to vary an opening area of the relief port in accordance with a variation of the pressure of the fuel flowing in through the inlet port; and a spring that urges the piston in a direction against the pressure of the fuel acting on the piston to regulate the pressure to be a specific value. Further, the cylinder and/or the piston is formed so that the piston opens the relief port at a relatively small speed per a unit displacement thereof in starting opening the relief port and subsequently at a relatively large speed.

Abstract: A valve, possibly for use in a paintball marker, has a longer threaded portion that insures a canister that engages the valve must undergo many twists to become unscrewed from the valve. Alternatively, the valve has an elongated threaded portion with gas bleed channels that extend along a substantial portion of the threading. Still alternatively, the valve may use visual markings along the length of the threaded portion to indicate to a user that the canister is being unscrewed.

Abstract: A valve body main unit has a circular step surface facing a circular valve seat surface of a valve chamber formed on a terminal end part of a fuel supply path to a fuel tank and a circular groove with one groove wall extending from the circular step surface, and is normally urged in a direction of closing an inflow port surrounded by the circular valve seat surface. The valve body main unit also has an elastic seal body with a ring shape inserted into the circular groove of the valve body main unit. The elastic seal body has a circular fin-shaped part projecting from an outer perimeter part and pushed against the circular valve seat surface by the urging of the valve body main unit to close the valve.

Abstract: A check valve includes a valve housing having a first housing portion including an inlet and a second housing portion having an outlet. A poppet valve is received in the housing and includes an outer surface having a diameter greater than the diameters of the inlet and outlet. A valve guide is also received in the valve housing and defines a variable volume pressure cavity and a fluid flow path. The valve guide is adapted to provide the variable volume pressure cavity in communication with the fluid flow path. A resiliently compressible member is adapted to bias the poppet valve toward a closed position against a flow of fluid through the check valve and a low pressure force created in the variable volume pressure cavity by virtue of the fluid flow through the valve guide.

Abstract: Progressive cavity pump assemblies including one or more mechanisms adapted to regulate intake pressure of the main pump between a minimum intake pressure and a maximum intake pressure. In one embodiment, the mechanism is a sealing member configured to open at a threshold pressure to discharge wellbore fluid and close after falling below the threshold pressure. In an alternative embodiment, the mechanism may be a regulator assembly that adjusts the volume of output from the charge pump to the interconnect according to the pressure in the interconnect.

Abstract: An air fitting with an integral check valve includes a housing having an inlet and at least one outlet, a passage extending between the inlet and the at least one outlet with a valve seat being formed in the passage adjacent the at least one outlet with a portion between the outlet and the valve having a plurality of channels separated by lands which form a guide surface for the valve as it is being forced onto the valve seat by a spring. The channels allow passage of air around the valve member with less restriction when the valve member is lifted off the valve seat.

Abstract: To protect hydraulic assemblies, in particular to protect hydraulic brace systems, pressure relief valves 1 are used, the closing part 10 of which is formed by a piston 15, which is connected to the connection 4, and the valve spring retainer 12, which comprises said piston, is arranged displaceably thereon and accordingly has a cylindrical design. Between the connection 4, which is equipped with a blind hole 5 and radial bores 6, 7, and the displaceable closing part 10 and/or the correspondingly shaped valve spring retainer 12 a damping chamber 20 is formed, which is directly connected to the blind hole 5 and hence to the system pressure.

Abstract: A high pressure valve assembly (10) comprising a valve sleeve (14) and a valve body (16) slidably mounted in the valve sleeve (14) is disclosed, the valve body (16) and valve sleeve (14) each having first ends (18, 56) and second ends (20, 58). A sidewall (22) extends between the valve sleeve first end (18) and second end (20) which sidewall (22) has an inner surface (24) and an outer surface (26) and at least one opening (30) therethrough. The sidewall (22) also includes at least one channel (40) having a first end (42) facing the inner surface (24) at a first location closer to the first valve sleeve end (18) than to the second valve sleeve end (20) and a second end (44) facing the inner surface (24) at a second location closer to the second valve sleeve end (20) than to the first valve sleeve end (18). A method of using the valve assembly (10) is also disclosed.

Abstract: What is disclosed is a non-return valve comprising a sealing piston which is biased against a valve seat in the basic position inside a valve housing, and which is manufactured by a plastics injection molding technique.

Abstract: The hydraulic distributor exhibits a cylindrical and internally-hollow body (2) having an inlet chamber (3) for a fluid and an outlet chamber (4) which are interconnected directly (by a communication conduit), or indirectly by an external distributor. A cursor (7) is axially mobile in the hollow body (2) and a closing element (12) is associated to the cursor (7) by elastic elements (11). The closing element (12) is mobile in the inlet chamber (3) between a first position in which it occludes the inlet chamber (3) and a second position in which it permits passage of fluid from an antechamber (3a) to a second opening (3b).

Abstract: A valve, possibly for use in a paintball marker, has a longer threaded portion that insures a canister that engages the valve must undergo many twists to become unscrewed from the valve. Alternatively, the valve has an elongated threaded portion with gas bleed channels that extend along a substantial portion of the threading. Still alternatively, the valve may use visual markings along the length of the threaded portion to indicate to a user that the canister is being unscrewed.

Abstract: A muffler with variable acoustic properties. A pressure cell with a diaphragm, a spring, a piston, a piston rod, a closing element on the piston rod, and a pressure connection line are integrated into a housing. The diaphragm is thermally insulated against the piston rod. Another layer of thermal insulation is provided between the closing element and the pressure cell.

Abstract: A valve, possibly for use in a paintball marker, has a longer threaded portion that insures a canister that engages the valve must undergo many twists to become unscrewed from the valve. Alternatively, the valve has an elongated threaded portion with gas bleed channels that extend along a substantial portion of the threading. Still alternatively, the valve may use visual markings along the length of the threaded portion to indicate to a user that the canister is being unscrewed.

Abstract: The unit of the invention comprises a motor-driven high pressure pump (11) having a delivery side (13) and a suction side (14), and a delivery gun (15) connected to the pump delivery side (13) by a delivery conduit (16) having a flow on-off valve. The valve unit comprises a by-pass valve (25, 33) arranged to close or alternatively, when in the open state, to enable direct flow passage between the delivery side (13) and the suction side (14), and having a control means (31, 32) sensitive to the liquid pressure in the delivery conduit (16); said control means comprises two valving elements (31, 32) which are normally joined together to form one piece in contact with the liquid of the delivery conduit (16), but which separate when the pressure in the delivery conduit (16) exceeds the normal delivery value (P1) following flow interruption by the delivery gun (15), to hence provide direct passage for the liquid from the delivery conduit (16) to the suction side (14).

Abstract: A closure device used in a fluid dispensing assembly. The closure device contains a housing, a poppet member, and a biasing member. The closure device provides a retaining structure for stabilizing and aligning the poppet member and biasing member within the housing.

Abstract: A backflow prevention valve includes a cylindrical case member with an inflow opening at one end and an outlet at the other end or a peripheral surface or both, and a valve member contacting a peripheral edge of the inflow opening for closing the inflow opening. An urging device urges the valve member toward the inflow opening, and a liquid inflow pipe is connected to the inflow opening from outside the case member. The liquid inflow pipe has a smooth inner surface without unevenness, and is attached to a fuel supply pipe inside the fuel tank. When the fuel is supplied, the valve member moves against an urging force of the urging device due to a fuel pressure, so that the inflow opening opens.

Abstract: A backflow prevention valve includes a cylindrical case member having a plurality of holes formed in an upper end at a periphery thereof, a valve member disposed in the case member to be movable in an axial direction thereof, an urging device disposed in the case member for urging the valve member upwardly, and a liquid inflow pipe extending outwardly from the case member. The valve member includes a sealing portion at an upper surface thereof for contacting a peripheral edge of an inflow opening to close the same, and a plurality of guiding arms provided on a peripheral edge of an upper surface of the valve member. The guiding arms are slidably disposed in the holes so that the valve member is supported and guided by the guiding arms passing through the holes.

Abstract: A pneumatic valve (10) for selectively controlling fluid flow through a pneumatic system of a vehicle is disclosed. The valve (10) includes a housing (12) having a cavity (28). The cavity includes an inlet (16) and an outlet (18). A flow controller (40) is disposed within the housing (12) for selectively controlling fluid flow through the housing (12). The flow controller (40) is actuatable to an open position, where the inlet (16) is in fluid communication with the cavity (28) and the outlet (18) is in fluid communication with a pneumatically operated device. The flow controller (40) is also actuatable to a closed position, where the flow controller (40) substantially impedes fluid from flowing through the housing (12). The flow controller (40) is actuatable between the open and closed positions in response to a predetermined fluid pressure within the pneumatic system.

Abstract: A check valve for connection in a fuel tank filler tube. The valve has a tubular body with a plurality of radially inwardly extending vanes or ribs in the inlet end about a portion of the circumference. The ribs are tapered in the flow direction to deflect the end of a siphoning hose to an offset opening. A valve seat and poppet with a tapered surface are disposed downstream of the ribs, clearance apertures are formed in the side of the tubular body downstream of the valve seat. The tapered surface of the poppet, upon being opened by insertion of the end of a siphoning hose deflects the hose outwardly through the clearance apertures to facilitate further insertion into the tank. The poppet is biased normally closed by a spring.

Abstract: A relief valve assembly including a valve member, having inlet and outlet bores, for sliding movement within a valve body bore portion, having a cylindrical sleeve portion, journalled via a cylindrical sleeve bearing for substantially the entire axial extent thereof, with a valve member head portion having a plurality of equally spaced apertures, connecting the inlet bore and a sleeve portion central cavity with the outlet bore. An annular resilient seal, having a flat-faced sealing surface is retained in the valve member head portion for sealingly engaging a valve body valve seat portion. A compression member, for biasing the valve member to a closed position, is operatively interposed between an adjustment member piston portion and a valve member sleeve cavity, the adjustment member having an adjustment stem for external adjustment of the compression member. A radial end thrust bearing, is interposed between the compression member and the adjustment member.

Abstract: A check valve comprises: a pair of cylindrical body elements (1, 4) through which a fluid passes; a cylindrical valve element (7), which is disposed inside an upstream-side one (4) of the cylindrical body elements (1, 4), constantly subjected to a fluid pressure and biased toward its closed position under the influence of a resilient force exerted by a compression coil spring (10) coated with a tubular element; and, a stopper element (24) disposed in a downstream-side one (4) of the cylindrical body elements (1, 4). The check valve is characterized in that at least one of the cylindrical valve element (7) and the stopper element (24) is provided with a spiral seat portion (11) an axial spiral surface of which is brought into stable surface-contact with the compression coil spring (10) to support the compression coil spring (10) therein.

Abstract: A check valve including an outer body having a cylindrical inner bore and a shuttle within the inner bore which is arranged with an upstream, middle and downstream portion that each engage with a sliding fit the inner bore of the outer body being such that, when in a closed position, the middle portion engages with a flexible seal a sealing engagement the inner bore and when in an open position it is arranged that the liquid will flow through a passage around the middle portion which passage includes at the least a path through the outer body.

Abstract: A check valve for a fuel pump of a vehicle includes a valve housing adapted to be disposed in an outlet member of the fuel pump and a valve seat formed on the valve housing. The check valve also includes a valve member disposed in the valve housing and having a closed position to engage the valve seat to prevent fuel from flowing through the outlet member and an open position to allow fuel to flow through the outlet member. The valve member has at least one outlet port a predetermined dwell distance from the valve seat when the valve member is in the closed position and allows fluid flow past the valve seat when the valve member is in the open position.

Abstract: A freezeless wall hydrant has a normally horizontal fluid inlet tube with an interior end and exterior end. A hollow valve fitting is rigidly secured to the interior end of the inlet tube for a connection to a source of pressurized fluid. A valve seat is located on an interior end of the valve fitting. An elongated hollow tube of a diameter less than the interior diameter of the inlet tube is positioned on the center line of the inlet tube and has inner and outer ends. A plug is rigidly secured to the inner end of the tube to close the inner end for fluid flow. A normally closed check valve is movably mounted in the tube to engage a valve seat on the plug, to open the tube for fluid therein under conditions of high fluid pressure in the inlet tube.

Abstract: A pressure limiting valve is provided which has a valve body assigned on the high-pressure side to a valve seat and an operating piston combined with the valve body to form a unit, wherein the valve body and the operating piston are jointly spring-loaded and bound a pressure space which can be opened as a function of pressure with respect to a connection cross-section open in the return flow by way of the operating piston moving in a sliding guide.

Abstract: A relief valve assembly including a valve member, having inlet and outlet bores, for sliding movement within a valve body bore portion, having a cylindrical sleeve portion, journalled via a cylindrical sleeve bearing for substantially the entire axial extent thereof, with a valve member head portion having a plurality of equally spaced apertures, connecting the inlet bore and a sleeve portion central cavity with the outlet bore. An annular resilient seal, having a flat-faced sealing surface is retained in the valve member head portion for sealingly engaging a valve body valve seat portion. A compression member, for biasing the valve member to a closed position, is operatively interposed between an adjustment member piston portion and a valve member sleeve cavity, the adjustment member having an adjustment stem for external adjustment of the compression member. A radial end thrust bearing, is interposed between the compression member and the adjustment member.

Abstract: The invention relates to a pressure regulating valve comprising a valve body having one or more inlet openings and one or more outlet openings for a pressurized medium, an internal cavity connecting said inlet and outlet openings and a piston which is in contact with a valve seat between inlet and outlet and is axially slidable in the cavity in the valve body against a spring, which biases the piston to a closed position, whereby the valve opens when a predetermined pressure acts on the piston. The valve body is provided with an opening at its outlet side, where the cross-section of the opening is smaller that the cross-section of the cavity and which opening is in connection with a volume limited by the piston and the lower section of the internal cavity, whereby the pressure drop across the valve dampens variations in the volume.

Abstract: There is disclosed a check valve for a tap of a gas or a liquefied gas cylinder comprising a valve body member axially movable in a housing bore. The body member has an axial bore opening out through one axial end of the valve body member and being in fluid communication with an annular space surrounding valve body member within the housing bore. The other axial end of the valve body member is closed and carries a primary seal ring gas tightly engaging an inner circumferential surface in the bore in the closed position of the check valve. There is provided a secondary seal ring at the first axial end of the valve body member.

Abstract: The invention relates to a device (10) for pressure regulation, having a housing (11) and a closing body (12) received axially movably therein, wherein the housing (11) has at least one pressure medium inlet (21) and one pressure medium outlet (22), and the closing body (12) is prestressed by a helical spring (14) against a valve seat (11′) in the housing, and at least one compensation means for the helical spring (14) is provided. The invention provides that as the compensation means, a compensation element (15) disposed between the closing body (12) and an end, oriented toward the closing body (12), of the helical spring (14) is provided, which is braced resiliently in the radial direction on the inner wall of the housing (11) and, with its central region (15′), is in preferably frictional-engagement contact with the closing body (12).

Abstract: A low deviation pressure relief valve for a fuel pump consisting of a housing having an elongated bore having a continuous wall, an axis, shoulders arranged on the wall so as to extend toward the axis. A ball in the housing has a diameter at least less than the diameter of the bore and a ball retainer located in the bore upstream from the shoulders forms a ball seat by pre-coining process. The ball is smaller than the retainer seat in diameter to ensure an edge seal with the ball. A spring coaxial with the axis located down stream from the ball retainer and supported on the shoulders, and the ball is located between the spring and the ball seat wherein low flow restriction is created and reduced pressure variation is created as fluid flows past the ball and less buckling in the spring is created by guide ribs.

Abstract: A backflow prevention valve includes a cylindrical case member with an inflow opening at one end and an outlet at the other end or a peripheral surface or both, and a valve member contacting a peripheral edge of the inflow opening for closing the inflow opening. An urging device urges the valve member toward the inflow opening, and a liquid inflow pipe is connected to the inflow opening from outside the case member. The liquid inflow pipe has a smooth inner surface without unevenness, and is attached to a fuel supply pipe inside the fuel tank. When the fuel is supplied, the valve member moves against an urging force of the urging device due to a fuel pressure, so that the inflow opening opens.

Abstract: A valve assembly for admitting a tube or fuel into a vehicle fuel tank is disclosed. The valve assembly has a fixed housing with an inlet, an outlet, a middle section and an inner surface with an opening. At least one projection depends from the inner surface between the inlet and the outlet. The projection deflects the tube toward and through the opening. A piston element, which is slidably mounted to the housing, is normally urged in a direction to close the outlet and the opening until the tube or fuel urges the piston element in an opposite direction.

Abstract: A high pressure fuel supply apparatus is constituted by a plunger reciprocating in a sleeve of a high pressure fuel pump so as to form a fuel pressurizing chamber between the plunger and the sleeve, a suction valve provided in a fuel suction port for sucking fuel into the fuel pressurizing chamber, and a discharge valve provided in a fuel discharge port for discharging fuel from the fuel pressurizing chamber into a high pressure fuel discharge passageway communicating with an internal combustion engine, the discharge valve reciprocating axially so as to perform an open/close operation, wherein the high pressure fuel supply apparatus further comprises a holder for regulating an axial reciprocating movement of the discharge valve in the open/close operation within a predetermined range.

Abstract: A closure device used in a fluid dispensing assembly. The closure device contains a housing, a poppet member, and a biasing member. The closure device provides a retaining structure for stabilizing and aligning the poppet member and biasing member within the housing.

Abstract: A dummy undersea hydraulic coupling member is disclosed for protecting an opposing undersea hydraulic coupling member when the hydraulic lines are not operating. The dummy undersea hydraulic coupling member has a water displacement expansion chamber with a piston therein that allows trapped water and/or air to move from the receiving chamber to the water displacement expansion chamber during connection of the dummy coupling member to the opposing coupling member.

Abstract: A pneumatic valve (10) for selectively controlling fluid flow through a pneumatic system of a vehicle is disclosed. The valve (10) includes a housing (12) having a cavity (28). The cavity includes an inlet (16) and an outlet (18). A flow controller (40) is disposed within the housing (12) for selectively controlling fluid flow through the housing (12). The flow controller (40) is actuatable to an open position, where the inlet (16) is in fluid communication with the cavity (28) and the outlet (18) is in fluid communication with a pneumatically operated device. The flow controller (40) is also actuatable to a closed position, where the flow controller (40) substantially impedes fluid from flowing through the housing (12). The flow controller (40) is actuatable between the open and closed positions in response to a predetermined fluid pressure within the pneumatic system.

Abstract: A valve assembly for admitting a tube or fuel into a vehicle fuel tank is disclosed. The valve assembly has a fixed housing with an inlet, an outlet, a middle section and an inner surface with an opening. At least one projection depends from the inner surface between the inlet and the outlet. The projection deflects the tube toward and through the opening. A piston element, which is slidably mounted to the housing, is normally urged in a direction to close the outlet and the opening until the tube or fuel urges the piston element in an opposite direction.

Abstract: A relief valve having blow down values of 5% or lower is disclosed. The low blow down values are the result of reducing friction within the relief valve. The relief valve includes a movable plunger. Clearance is provided whereby the plunger does not experience significant friction as it moves into sealing contact with the seal assembly. An energized seal assembly forms a tight seal against the plunger while creating little friction, as the seal is elastomeric and the point of contact is minimized. The relief valve further includes an outlet port, which is adjustable 360° about the relief valve.

Abstract: A relief valve for regulating discharged oil pressure of an oil pump at a predetermined level comprises a cylinder including a bore therein and relief grooves formed symmetrically relatively to an axial center of the bore, while each of the relief grooves has a respective opening to an inner peripheral portion of the bore; a valve body disposed in the cylinder so as to be slidably moved in the bore in response to the discharged oil pressure supplied into the bore at one side of the valve body; a spring provided in the other side of the valve body constantly urging the valve body toward the one side of the valve body so as to close the openings of the relief grooves by the valve body; and an adjusting means for adjusting a change rate of an opening area of the relief grooves relatively to one slide movement of the valve body against the force of the spring so that the change rate of the opening area at the beginning of slide movement of the valve body is smaller than that at the end of the slide movement of th

Abstract: A pressure relief valve and method of preparation is provided in which the relief valve includes a body having a seat disposed in a passageway. The relief valve also includes a piston sealing a gasket against the seat by a spring. The spring is adjusted and retained by an adjusting gland. The piston includes a cone that aids in reclosing the valve quicker than it would close without the cone. The relief valve has a low blowdown and may be easily assembled and then shipped on the same day.

Abstract: A relief valve having blow down values of 5% or lower is disclosed. The low blow down values are the result of reducing friction within the relief valve. The relief valve includes a movable plunger. Clearance is provided whereby the plunger does not experience significant friction as it moves into sealing contact with the seal assembly. An energized seal assembly forms a tight seal against the plunger while creating little friction, as the seal is elastomeric and the point of contact is minimized. The relief valve further includes an outlet port, which is adjustable 360° about the relief valve.

Abstract: A pressure relief valve has a main valve body, a fluid inlet passageway, a fluid outlet passageway, and a piston contained within the main body. The piston has a piston head, slidingly and sealingly engaged within a pressurized cavity in the main valve body. The piston head's principal face, having a given surface area, is exposed to a pressurized gas in the cavity. A piston stem, connected to the piston head, is in sliding communication with a packoff assembly and has an exposed face whose surface area is smaller than the piston head's principal face. The piston stem's exposed face is in communication with the pressurized gas or fluids to be regulated. In operation, a gas or fluid pressurized to a predetermined value in the pressurized cavity acts against the piston head, forcing one or more ports in the piston stem sidewall to be sealed from the fluid outlet passageway.

Abstract: A relief valve assembly, comprises: a relief valve; a valve housing including a valve path along which the relief valve can slide; a relief inflow portion formed on one end of the valve housing; and relief discharge portions formed at an intermediate location of the valve path of the valve housing and provided with small aperture portions axed large aperture portions formed in communication with one another. A side wherein the relief discharge portions are provided with the small aperture portions is the side near the relief inflow portion.