Abstract: A hyper-reset pressure controller which includes two separate feedback paths which results in a substantially smoother and more accurate pressure control.

Abstract: An automatic control valve has a main valve member moveable between open and closed positions thereof in response to pressure applied to a first piston or diaphragm in a first control chamber. The valve member moves to modulate flow through the valve to maintain desired flow conditions. Pilot pressure signals are generated to reflect the flow conditions, usually upstream and downstream from the valve, which signals are processed to generate a control signal which is fed to the first control chamber to control pressure therein. Normal movement of the valve produces wear which causes leakage of the diaphragm or seals oft he piston causing loss of primary control of the valve member which tends to fail "open". This causes an initial rise in flow through the valve which is detected by the pilot pressure signal but because of the leakage, is unable to correct.

Abstract: A low-energy-consuming apparatus and method for controlling vacuum levels in machine milking and other vacuum systems subject to air leakage utilizes in combination a high vacuum reserve, a low-vacuum end (pipelines), a dual vacuum controller positioned between the high-vacuum reserve and the low-vacuum end and an adjustable speed drive (ASD) motor on a vacuum pump to regulate the delivered air to match the air usage in the low-vacuum end. The dual vacuum controller senses vacuum disturbances in the low-vacuum end and adjusts the flow rate of air from the low-vacuum end to the high-vacuum reserve rather than using external air makeup, thus providing a controlled vacuum with minimum pressure variance and energy input. Energy savings and demand reduction of about 50 percent (50%) during milking are realized under the new system.

Abstract: A surge relief valve suitable for high pressure application, for example in a crude oil pumped pipeline. The valve has a plug movable to expose different areas of an energy-absorbing cage trim to fluid flow. The plug position is controlled by a control device proportionately responsive to changes in upstream fluid pressure. The valve requires no external power for its actuation.

Abstract: A tube separator comprises an inlet and an outlet to define a flow direction from the inlet to the outlet, shut-off means arranged between the inlet and the outlet for connecting the inlet with the outlet in a first position thereof and for disconnecting the inlet from the outlet in a second position thereof, control means for operating the shut-off means and a non-return valve at the outlet for blocking or allowing fluid flow from the inlet to the outlet. The shut-off means comprises a shut-off member being arranged in the shut-off means for rotation around an axis perpendicular to the flow direction from a first rotational position to a second rotational position thereof, and a bore is provided in the shut-off member for connecting the inlet with the outlet in the first rotational position and for disconnecting the inlet from the outlet in the second rotational position.

Abstract: An accumulator loading valve is provided which is adapted for elevated pressures, which requires but little space, and which has a pump connection (1), a reservoir connection (20), a priority valve (7) between the consumer connection and the accumulator connection, and a pilot valve (4) being controlled by the accumulator pressure. The improvement is that the operating piston of the two-position pilot valve (4) is prestressed by a spring (28) having a constant spring rate and that the cross section of the valve inlet (19) is smaller than the cross section of the valve discharge (20).

Abstract: There is disclosed a pilot operated pressure-reducing valve system incorporating a main valve and a pilot valve, the latter being either near or remote from the main valve. The pilot and main valves cooperate with each other in such manner that the main valve will close very rapidly, this being important in aircraft fueling systems for example. Two related poppets are provided in the pilot valve, one such poppet being adapted to permit high flow for achievement of the substantially instantaneous main valve closure.

Abstract: A back pressure control device is connected to the actuator of a control valve to limit the amount of gas released from the actuator after each actuation. Approximately two thirds of the volume of the actuation gas is retained in the actuator by the subject device after each actuation, this being both the release of a sufficient volume to assure actuation of the control valve while retaining gas which was heretofore wasted.

Abstract: A device and method are shown for controlling tank vapors on a petroleum storage tank of the type having a tank vapor line which runs to a suction scrubber. The scrubber being connected by conduit to a reciprocating compressor which, in turn, is connected to a compressed vapor discharge line for passing compressed vapors to a gas sales line. The reciprocating compressor is operated to draw tank vapor through the suction scrubber and through the reciprocating compressor to discharge vapor through the compressed vapor discharge line. A pneumatic control valve is installed in the tank vapor line for controlling the flow of tank vapors to the suction scrubber. A pilot valve is provided as a part of the pneumatic control valve for controlling the operation of the control valve. The control valve is operated to maintain a vacuum in the tank vapor line between the control valve and the suction scrubber to eliminate the tendency of tank vapor to liquify in the tank vapor line.

Abstract: A tank blanketing valve in which a biased piston is positioned to control the flow of source gas into the tank. The piston is biased by a spring and a pilot gas stream from the source gas (the biasing pressure or force) to close the tank gas inlet. The pilot gas stream is controlled by a pressure sensing component of the valve, whereby the pilot gas stream is directed away from the biased piston when the pressure in the tank is less than a predetermined pressure. This reduces the biasing pressure which is holding the piston in the gas inlet line to the tank. The pressure of the source gas on the piston in the source gas inlet line then exceeds the biasing pressure and causes the piston to slide open and admit source gas into the tank.

Abstract: A pressure relief valve (14, 14A) has a reciprocable valve member (34, 34A) for seating on an annular seat face (66,66A) of a nozzle assembly (38,38A). The nozzle assembly (38,38A) has an inner seat ring (40,40A), a radially outer anchor ring (42,42A), and a flexible connecting member (44,44A) extending in a generally radial direction between the outer peripheral surface (64) of the seat ring (40,40A) and the inner peripheral surface of the anchor ring (42,42A). Upon seating or reseating of the valve member, (34,34A), seal face (36,36A) contacts the seat face (66,66A) of seat ring (40,40A) and flexible connecting member (44,44A) flexes upon relative movement of the seat ring (40,40A) after initial contact of the valve member (34,34A) against the seating ring (40,40A) thereby to act as a shock absorber for absorbing impact forces.

Abstract: A pilot regulator has a main housing with a sensing chamber and a separate receiving chamber. The sensing chamber connects to the system for sensing. The receiving chamber is adapted to connect its inlet to the system upstream of the pilot and to the load line of the valve to be controlled and to connect its outlet downstream thereof, a cartridge containing a complete valve is removably received in the receiving chamber in position to control flow therethrough between the inlet and outlet. And a mechanism is disclosed for opening and closing the valve in response to sensing chamber pressure changes. The cartridge with its valve are removable as a unit for repair, mode change or replacement without disturbing connections to system.

Abstract: A valve comprising a rigid tube in which a flexible tube is situated with the two ends of the flexible tube being connected in sealed manner to the ends of the rigid tube, a control orifice being provided through the wall of the rigid tube in the vicinity of its middle region, and a core also being disposed inside the flexible tube, the core being smaller in cross-section than the inside section of the tube when in the rest state, wherein the core has a calibrated internal passage. The valve is suitable for preventing hammer in an installation having two zones at different pressures P1 and P2.

Abstract: A valve for use e.g. as a pilot valve in an offshore water deluge fire fighting system has a ported cylindrical body and an elastomeric sleeve defining between them an annular passage for flow between the various ports. Selected ports can be closed by means of captive balls which are cammed out by a central spool to deform localized areas of the sleeve into sealing contact with the housing wall surrounding the port openings. In this way the moving parts of the valve are isolated from the fluid by the sleeve and problems of sticking, e.g. caused by salt deposits when used with seawater, are avoided. In another embodiment, a flat pad of elastomeric material is used to the same effect in a ported body defining a planar flow passage.

Abstract: A pilot valve (40) for a control valve (14) has a separate auxiliary source of high pressure fluid (106) for the operation of the pilot valve (40). The dome chamber (36) of the control valve (14), the inlet fluid chamber (72), and the intermediate fluid chamber (104) are exposed only to the auxiliary source of fluid (106). Thus, process fluid from the sensing line (62) does not contaminate the spool valve (76) or the dome chamber (36).

Abstract: A flow control device illustrated as a pressure relief valve (10, 10A) has a reciprocable valve member (22, 22A) for seating on a face (20, 20A) of a fixed seat ring (18, 18A). The valve member (22, 22A) includes a hub (36, 36A), an outer seal ring (38, 38A), and a flexible connecting member (40, 40A) extending between and connecting the seal ring (38, 38A) and the hub (36, 36A). Upon seating or reseating of valve member (22, 22A) seal ring (38, 38A) contacts fixed seat ring (18, 18A) and flexible connecting member (40, 40A) flexes upon relative movement of the hub (36, 36A) after initial contact of the seal ring (38, 38A) with the fixed seat ring (20, 20A) to act as a shock absorber for absorbing impact forces.

Abstract: The invention relates to a brandnew multi-function static-errorless pressure control method and the valve thereof, in which a cylindrical two-side three-way valve is used as the pilot valve 20 and an asymmetric double-action differential hydraulic cylinder is used as the main valve 10 to constitute an 1-type static-errorless closed-loop negative feedback control system, a transfer means with special oil network connects to the oil circuits 1, 2, 8 and ports 4, 5, 9, L of the system and makes the valve to correspond to six operating modes of the relief valve, remote control relief valve, constant valve pressure reducing valve, constant difference pressure reducing valve, internal control sequence valve and external control sequence valve respectively. The test results have shown that the static error of the pressure control valve of present invention is 0.5%, the overshoot is less than 5%, and no self-excitation is found.

Abstract: A pilot operated relief valve which includes a non-flowing modulated pilot valve and a main valve. The pilot utilizes a torsion device in connection with transducers and valves. The transducers relate variations in pressure within the valve system to the torsion device. The torsion device, in turn, acts to open and close various ports of the pilot valve so as to achieve modulated relief of overpressurized fluid from a pressure system. In addition, the torsion device can be manipulated to provide for easily achieved and accurate set pressure positions.

Abstract: A carbonator unit for a post-mix beverage dispenser having a carbonator tank immersed in a liquid flotation tank. The carbonator tank floats up and down with changes in the amount of water and head space in the carbonator tank to actuate a switch device mounted externally of the carbonator tank. Actuation of the switch causes a water pump to become operative to supply uncarbonated water to the carbonator tank. When the volume of carbonated water increases to a predetermined amount, the carbonator tank sinks to deactivate the switch.

Abstract: A pilot valve operates a main safety relief valve. Two signal sources are registered separately by the pilot valve's pressure cavities for greater sensitivity and modulating action in a non-flowing design.

Abstract: An unloader device for controlling the output of a hydraulic pump, for example, in a constant pressure-type motor vehicle braking circuit. Delivery to hydraulic accumulators in the circuit is halted by a resilient seal defining an annulus forming part of the inlet fluid flow path to the pump and to which the pump delivery pressure is applied to expand the seal in the sense to close the annulus, by a valve operable when the delivery pressure reaches a predetermined value.

Abstract: A pilot operated relief valve which includes a non-flowing modulated pilot valve and a main valve. The pilot utilizes a torsion device in connection with transducers and valves. The transducers relate variations in pressure within the valve system to the torsion device. The torsion device, in turn, acts to open and close various ports of the pilot valve so as to achieve modulated relief of overpressurized fluid from a pressure system. In addition, the torsion device can be manipulated to provide for easily achieved and accurate set pressure positions.

Abstract: The supply of a pressure fluid to one or more outlets additional to a permanent outlet is controlled by the provision for the or each additional outlet of a pressure fluid circuit including sources of higher and lower reference pressure fluids and three comparator valves using the reference pressure fluids and the pressure fluid to connect the pressure fluid to the additional outlet when the pressure fluid pressure exceeds the higher reference pressure and to disconnect the pressure fluid from the additional outlet when the pressure fluid pressure falls below the lower reference pressure.

Abstract: The invention relates to a control system for adjusting the setting of a damper (9) in a ventilation duct (8) and maintaining a substantially constant pressure at a selected region in the ventilation duct, the system comprising a cylinder (1) having a vertical cylinder axis and housing a readily movable, pressure-responsive device (2), which together with the cylinder defines a pressure space. The pressure space (22) communicates with the ventilation duct at the aforementioned selected region, and drive means (11, 12) are provided for adjusting the damper setting in response to the position of the pressure-responsive device, so as to maintain a constant pressure. The inventive system is characterized in that the pressure-sensitive device (2) has a mass which corresponds to a selected pressure at the aforementioned region in the duct and is intended to balance the pressure force acting on the device.

Abstract: A main valve includes a product pressure inlet, an outlet, a movable closure member and a pressurized head volume above the closure member. Product pressure relief flow through the main valve is controlled by a modulating, pressure operated pilot relief valve that includes a piston chamber with a reciprocally mounted pilot piston. The chamber is in fluid communication with the pressurized head volume and with the outlet and inlet of the main valve. An inlet valve controls flow from the inlet of the main valve into the chamber and is actuated by the pilot piston. A vent valve is mounted within the piston chamber and controls fluid flow from the piston chamber to the outlet of the main valve and is actuated by the pilot piston.

Abstract: A flapper actuated pilot valve is shown is which the output pressure from the valve is dependent upon and proportional to the force exerted by the flapper. The valve includes a valve body with upper and lower chambers and an interconnecting gas passage. A spring-biased poppet in the lower chamber has a primary sealing surface for sealing off the lower chamber and a secondary sealing surface which is contacted by a flapper element located in the upper chamber. The flapper element has an interior bore leading to an exhaust port in the upper end of the flapper element which extends through an opening in the valve body. The flapper element also extends through a central opening provided in a cupped seal in the upper chamber. The cupped seal and primary and secondary sealing areas of the flapper element cooperate to provide and outlet gas pressure which is proportional to the external force supplied by the flapper upon the flapper element.

Abstract: A tube separator (1) having a shut-off means for separating an inlet side (2) from an outlet side (3) is provided. In order to prevent flutter of the shut-off means (4) in a pressure region changing over the shut-off means, a control valve (10) controlling the shut-off means (4) is provided. The control valve (10) is designed such that the pressure required for changing over from a first opened position to a second shut-off position is smaller than the pressure for changing over from the second into the first position.

Abstract: A main valve includes a product pressure inlet, an outlet, a movable closure member and a pressurized head volume above the closure member. Product pressure relief flow through the main valve is controlled by a modulating, pressure operated pilot relief valve that includes a piston chamber with a reciprocally mounted pilot piston. The chamber is in fluid communication with the pressurized head volume and with the outlet and inlet of the main valve. An inlet valve controls flow from the inlet of the main valve into the chamber and is actuated by the pilot piston. A vent valve is mounted within the piston chamber and controls fluid flow from the piston chamber to the outlet of the main valve and is actuated by the pilot piston. The pilot piston includes first and second surfaces and effective areas exposed to the pressure in the piston chamber and an end isolated from the piston chamber and in fluid communication with the main valve inlet.

Abstract: Wellhead flow control valve including a valve body, a hydraulic linear actuator means connected to valve body in alignment with operating chamber. Actuator has Belleville spring return. A seat sleeve carrying a valve seat and an internal lining mounts at outlet of operating chamber. Drive shaft moves flow control member of prescribed configuration into and out of valve seat sleeve. Flow control member and valve seat cause complete flow closure. Hydraulic conduit connects into actuator to admit hydraulic fluid to move piston and to compress spring. Activator is responsive to a pilot signal for: activating a pump control switch; to permit operation of pumps; activating a by-pass valve switch to keep closed a by-pass valve between conduit and sump of pump; and activating a blocking valve switch to keep open a blocking valve connected between pump and actuator.

Abstract: A pipe separator (1) comprising a control valve (7) for actuating a sliding valve (4) is provided. In order to increase the service time of the sliding valve by avoiding an unnecessary switching frequency, a two positions-three directions directional valve acting as a damping element is additionally provided.

Abstract: The pilot valve 206 disclosed utilizes a piston 226 operating intermediate a pressure setting spring 234 and main valve head volume 222 vent valve, and having a single pressure sensing chamber 235. The operating piston includes an elongated extension 229 of reduced diameter extending from the piston adjacent the sensing chamber and incorporates an opposite end, secondary relief chamber 230 providing main valve operation at pressures fixedly related to the operating piston relief setting. The piston extension operates the vent valve 245 in an adjacent chamber. The piston further defines an internal cavity 240 containing a somewhat coaxial inlet valve 251, 252. Inlet and exhaust valves are in fluid communication through said piston extension. Main valve head volume venting and pressurizing is accomplished through valve body ports cooperating with said inlet and exhaust valves.

Abstract: A safety relief system for a valve in a vent or a main flowline. The safety relief system utilizes a main actuator (24) utilized primarily for a positive pressure condition and a vacuum actuator (96) in axial alignment with the main actuator (24) utilized exclusively for a negative pressure condition. The main valve member (18) has a stem (22) which extends within both actuators (24, 96) and diaphragms (26, 100) are connected to the stem (22) for movement of the valve member (18).

Abstract: A cylinder valve for mounting on a high pressure gas cylinder for remotely controlling the flow of gas from the cylinder. The cylinder valve is resistant to hazardous gases and includes a fluid passage for conveying gas through the cylinder valve from an inlet for communicating with the high pressure gas cylinder to an outlet. A first valve is provided for opening and closing the fluid passage to control the flow of gas through the fluid passage. A pneumatically operated actuator is provided for operating the first valve in response to the application of an external control pressure to the actuator. A mechanism is provided to move the first valve and close the fluid passage in the event of loss of external control pressure to the actuator. A second valve is located downstream of the first valve in the vicinity of the outlet. The second valve is biased to close the fluid passage but is moved to open the passage in response to attachment of a connector to the outlet of the cylinder valve.

Abstract: A pneumatic pressure regulating system controls a choke having a hydraulic operator actuator for selectively opening or closing the choke to control pressure in a well casing. The system applies periodic pulses of pneumatic pressure for opening an output valve in one direction when the actual casing pressure is greater than a selected control pressure for opening the choke, and applies periodic pulses of pneumatic pressure for opening the output valve in another direction when casing pressure is less than the set pressure for closing the choke. The interval between sucessive pulses is adjusted to be long enough for the pressure in the casing to equilibrate before the next pulse occurs.

Abstract: The point at which pump out pressure exceeds load is sensed to provide a point for scheduling flow to an actuator in a hydraulic system. Flow is controlled by a stepper motor (28) that moves a flow control valve (27). The steps needed to achieve fixed flow changes are greater for high flow positions. When the pump (21) is turned on, the valve (27) is positioned to bypass flow; the bypass flow is then programmably decreased to the actuator. Reverse flow is regulated by the valve (27) to control actuator retraction. Reverse flow is initiated by opening a check valve (40) with an actuator (50) that opens it first to reduce pressure across the valve, then fully. The flow control valve (27) also operates to relieve excess pressure in the system.

Abstract: A flapper actuated pilot valve is shown in which the output pressure from the valve is dependent upon and proportional to the force exerted by the flapper. The valve includes a valve body with upper and lower chambers and an interconnecting gas passage. A spring-biased poppet in the lower chamber has a primary sealing surface for sealing off the lower chamber and a secondary sealing surface which is contacted by a flapper element located in the upper chamber. The flapper element has an interior bore leading to an exhaust port in an upper end of the flapper element which extends through an opening in the valve body. The flapper element is supported within the upper chamber by means of a pressure sensitive diaphragm. The diaphragm area and primary and secondary sealing areas cooperate so that to provide an outlet gas pressure which is proportional to the external force supplied by the flapper upon the flapper element.

Abstract: A testing device (22) for a non-flowing pilot valve (20) controlling a main relief valve (13) and simulating the action of the relief valve (13). The testing device body (84) has a test fluid source (42) releasably connected thereto and includes a piston valve element (112) mounted in a valve chamber (106) for movement to an unseated vent position upon the test fluid pressure reaching a predetermined high which is usually similar to the set point operating fluid pressure at which the main relief valve (13) will actuate. For return of piston valve element (112) to a seated position after a reduction of the test fluid pressure by venting, a relatively large diameter end face (128) is exposed to fluid pressure from an intermediate fluid chamber (78) of the pilot valve (20) which is in fluid communication with the dome (14) of the pressure relief valve (13). A relatively small fluid pressure responsive area of piston (113) outwardly of small diameter O-ring (120) is exposed to test fluid pressure.

Abstract: The point at which pump out pressure exceeds load is sensed to provide a point for scheduling flow to an actuator in a hydraulic system. Flow is controlled by a stepper motor (28) that moves a flow control valve (27). The steps needed to achieve fixed flow changes are greater for high flow positions. When the pump (21) is turned on, the valve (27) is positioned to bypass flow; the bypass flow is then programmably decreased to the actuator. Reverse flow is regulated by the valve (27) to control actuator retraction. Reverse flow is initiated by opening a check valve (40) with an actuator (50) that opens it first to reduce pressure across the valve, then fully. The flow control valve (27) also operates to relieve excess pressure in the system.

Abstract: Autonomous assistance device for a safety valve protecting a vessel under pressure and comprising a hollow body (13), a seat cooperating with a movable closure member fixed to a rod (9), and a calibrated spring (7) bearing against the rod (9) and against the valve body (13) to hold the closure member against the seat. The closure member rod (9) is extended into a casing (19) fastened to the body (13) and receives the additional thrust of a spring (51). The casing (19) constitutes in addition a pneumatic ram whose piston (53) can apply to the rod (9) a thrust opposite to and greater than that of the spring (51). The device feeding the ram (19) comprises an autonomous reservoir (33), a three-way solenoid valve (24) for feeding the ram or connecting it to atmosphere, and a manometer contact (39) mounted on the wall of the pressure vessel and adjusted to close the solenoid valve supply circuit when the pressure in the vessel reaches the adjusted pressure.

Abstract: Wellhead flow control valve including a valve body, a hydraulic linear actuator means connected to valve body in alignment with operating chamber. Actuator has Belleville spring return. A seat sleeve carrying a valve seat and an internal lining mounts at outlet of operating chamber. Drive shaft moves flow control member of prescribed configuration into and out of valve seat sleeve. Flow control member and valve seat cause complete flow closure. Hydraulic conduit connects into actuator to admit hydraulic fluid to move piston and to compress spring. Activator is responsive to a pilot signal for: activating a pump control switch; to permit operation of pumps; activating a by-pass valve switch to keep closed a by-pass valve between conduit and sump of pump; and activating a blocking valve switch to keep open a blocking valve connected between pump and actuator.

Abstract: A regulating valve having a fail-safe action which is suitable for controlling the flow of either a heating or cooling medium in response to a sensed condition is disclosed. The flow of heating or cooling medium is responsive to changes in temperature at a selected location, which changes are sensed by thermal element. The fail-safe action of the regulating valve either permits or prevents flow of the heating or cooling medium upon failure of the thermal element.

Abstract: A fluid pressure boost attachment (18) is attached to a pilot valve (16) which senses the fluid pressure in a main flow line F. Upon restriction or blockage of fluid flow through inlet line (32) to pilot valve (16) the correct static fluid pressure is sensed in auxiliary fluid chamber (126) of boost attachment (18). Boost attachment (18) is actuated upon a predetermined pressure differential being reached between chambers (100) and (126) thereby to move actuator (120) and place intermediate fluid chamber (24) of pilot valve (16) in fluid communication with outlet fluid chamber (28) thereof.

Abstract: A differential pressure regulator is arranged in series on the inflow side of a variable throttle for adjustment of a flow rate. An inlet pressure of the variable throttle is led into a primary pilot chamber of the differential pressure regulator. A constant flow control valve is provided in an oil passage connecting an oil passage on the inflow side of the differential pressure regulator with a secondary pilot chamber in order to allow a fluid of a constant flow rate to flow. The inflow side of a sequence valve is connected to the side of the secondary pilot chamber of the differential pressure regulator. The outflow side of the sequence valve is connected to the outlet side of the variable throttle or a tank. The inlet passage of the variable throttle is led into the primary pilot chamber of the sequence valve. An outlet pressure of the variable throttle is led into the secondary pilot chamber of the sequence valve. Further a check valve or a throttle is connected in parallel to the sequence valve.

Abstract: The invention relates to a device for protecting a container containing a pressurized fluid.The device comprises a protection valve and an isolating valve, connected in series and whose opening is controlled by ancillary means, which are sensitive to two pressure thresholds in the container for successively controlling the opening of the isolating valve and then that of the protection valve, when the pressure rises. The isolating valve replaces the protection valve in the case where the latter becomes locked in the open position.Application more particularly to the protection of primary circuits in a pressurized water nuclear reactor.

Abstract: To provide pressure regulation, limit pressure rise rate and control the speed of a fluid operated system with a control valve, a pilot operated valve member is in communication with a fluid passageway on both the inlet and outlet sides of a butterfly valve. The pilot operated valve member is also in communication with an actuator operable to move the butterfly valve between a closed position and an open position dependent upon fluid pressure on the inlet side and outlet side of the butterfly valve. By utilizing fluid pressure signals delivered to three separate chambers, the pilot operated valve member is capable of controlling valve opening ramp rate, pressure variations within the limit of a set point, and adjustability of the set point.

Abstract: A main valve includes a product pressure inlet, an outlet, a movable closure member and a pressurized head volume above the closure member. Product pressure relief flow through the main valve is controlled by a modulating, pressure operated pilot relief valve that includes a piston chamber with a reciprocally mounted pilot piston. The chamber is in fluid communication with the pressurized head volume and with the outlet and inlet of the main valve. An inlet valve controls flow from the inlet of the main valve into the chamber and is actuated by the pilot piston. A vent valve is mounted within the piston chamber and controls fluid flow from the piston chamber to the outlet of the main valve and is actuated by the pilot piston. The pilot piston includes first and second surfaces and effective areas exposed to the pressure in the piston chamber and an end isolated from the piston chamber and in fluid communication with the main valve inlet.

Abstract: A pressure control valve for maintaining a control pressure constant even if the flow rate of pressurized oil varies, and an oil supply apparatus adapted for a turbo machine using this pressure control valve. The pressure control valve drives a throttle valve by a hydraulic cylinder through the operation of the piston of the cylinder by a guide valve. A port is formed so as to throttle and release the oil at the input side to control the pressure at the inlet side of the valve, oil from the output side for controlling the pressure is guided to the guide valve, and the cylinder communicates with an oil pressure source through the guide valve. An oil supply apparatus which has this pressure control valve guides a pilot tube leading from the header which feeds to the load side of the guide valve, and guides the pressurized oil from the conduit between the pressurized oil supply source to the header and to the throttle valve, thereby releasing the pressurized oil to an oil tank.

Abstract: A non-flowing pilot valve (16) for a control valve (C) in a main flow line (F) having a body (27) with an inlet fluid chamber (76), an outlet fluid chamber (106) and an intermediate fluid chamber (104) between the inlet fluid chamber (76) and the outlet fluid chamber (106). Diaphragm (34) in the fluid inlet chamber (76) is secured to a piston slidable body (40) extending within intermediate fluid chamber (104) and having a valve seat (88) thereon between inlet fluid chamber (76) and intermediate fluid chamber (104). A second fixed valve seat (64) is provided within the body (40) between the intermediate fluid chamber (104) and the outlet fluid chamber (106). A valve spool (92) has a pair of O-ring seals (94, 96) thereabout adapted to seal against the valve seats (88, 64).

Abstract: The invention relates to a shut-off valve equipped with two pilot-valves and a main control-piston, the said valve connecting in inlet with an outlet when an upper switching pressure is reached and breaking this connection again when the pressure drops to a lower switching pressure. In order to reduce leakage and to improve the switching process, the pilot-valve (12), which determines the lower switching pressure, is in the form of a seat-valve held open by spring-force, the said pilot-valve closing off a control-line when the lower switching pressure is exceeded, and a second flow-path (21) being provided which is interrupted both by the main control-piston (3), in the shut-off phase, and by the pilot-valve (13) which determines the upper switching pressure, at least when, and shortly after, the shut-off (see drawing).

Abstract: A pilot operated pressure relief valve system having a modulating action. The pilot valve is of the non-flowing type and comprises sleeve and control stem members translating within a channel. The sleeve member comprises an exhaust valve for relieving dome pressure on the relief valve when lifted by the control stem. The control stem translates in response to system pressure changes and comprises an inlet valve cooperating with a seat on the sleeve member to form an inlet valve closable to isolate the dome from the system pressure when the latter reaches a level predetermined in relation to a set pressure.