Abstract: In the embodiment shown, the invention comprises a suction/check valve interposed in a gas inlet channel, the channel being open at one end for communication with the atmosphere, and at the opposite end for communication with a gas compressor inlet port. The valve has a bleed hole formed therein for slowly blowing down the compressor receiver at shutdown. A second check valve is operatively interposed between the receiver and the atmosphere for depressurizing the receiver when the compressor unloads. A conduit which communicates with both valves provides a valve-operating, fluid, pilot-pressure to close off the suction/check valve, and to interdict its bleed hole, and to open the second check valve, with compressor unloading.

Abstract: An electromagnetic plunger pump of the reciprocating type including a vent valve means which allows only air bubbles in the pump to pass therethrough. This vent valve means is provided in a pressure adjusting plunger fitted in a pressure adjusting cylinder for reciprocating motion. The vent valve means comprises a vent valve rod which is fitted in a through-hole of the pressure adjusting plunger so as to form a passage about the vent valve rod, and a vent valve body which is normally energized by a spring in the direction away from a vent valve seat at a forward end of the pressure adjusting plunger to provide a clearance between the vent valve body and the vent valve seat. This clearance is such that it allows the air bubbles to pass therethrough, while it does not allow a liquid under pressure having a viscosity to pass therethrough with the result that the vent valve means is closed by such liquid under pressure.

Abstract: A modulating flow control valve assembly having a bypass extending from the face of the valve through the valve and the means by which the valve is mounted within the valve body. As the valve moves within the valve body in response to fluid demands, the amount of bypass fluid is varied accordingly by controlling the amount of fluid permitted to pass through the bypass.

Abstract: A bypass valve includes a valve body containing a spring loaded valve member. The valve body includes first and second interconnected bores respectively connected to the outlet and inlet of a fluid pump feeding a fluid function. A valve member slidably disposed in the valve bores includes a cylindrical portion and a frusto-conical portion cooperating with the first and second bores to provide a predetermined pressure drop across both portions at a first flow rate with cold fluid and at a second flow rate with hot fluid. The spring is set so as to allow fluid to bypass from the pump outlet to the inlet until the predetermined pressure drop is exceeded.

Abstract: A combination by-pass and check valve for use in a fluid flow system comprising a valve body having an inlet and outlet and a passage therethrough. A seat disposed in the valve body between the inlet and outlet for location of a check disc thereon, the disc and seat cooperating to prevent fluid flow from the outlet to the inlet. A sleeve having one or more orifices therein extends from the check disc and substantially surrounds a portion of a perforate tubular by-pass located intermediate the seating surface and the inlet. The orifices in the sleeve and the perforations in the by-pass are in at least partial alignment and communication when the disc is on the seat, permitting fluid flow through the by-pass. When fluid flow from the inlet to the outlet has raised the disc a substantial distance off the seat, the orifices in the sleeve are non-aligned with the perforations on the by-pass, preventing fluid flow through the by-pass.

Abstract: A combined unloader and check valve for use with a motor driven air compressor (70) in which pressure trapped in the compressor head when the compressor is shut down is unloaded by means of an unloaded valve element (44) which opens a port (26) to unload the head pressure to atmosphere through an exhaust port (62) in response to the closing of a check valve element (34) in the compressor outlet line. When the compressor is operating and the check valve is open, pressure above the unloading valve element keeps the unloading valve element in position to shut off flow through the exhaust port. Air trapped above the unloader valve element when the check valve is initially closed is bled off through a filter element (52). In a preferred embodiment of the invention, the unloader valve element (144) is in the form of a diaphragm. The filter element (52) can be a compressible material to permit adjustment of the bleed rate therethrough by varying the density thereof by means of an adjustable bleed screw (48).

Abstract: A differential pressure relief valve formed of a housing having first and second chambers sealed from the atmosphere and separated by an annular diaphragm with the chambers and the annulus of the diaphragm traversed by a moveable sleeve. The first chamber communicates to a primary pressure source through a first channel in the housing and the second chamber communicates to a secondary pressure source through holes provided in the sleeve and then to a second channel in the housing. The end of the sleeve protruding from the second chamber is engageable with a seat in the housing. The arrangement is such that when the primary pressure exceeds the secondary pressure by a predetermined amount, the end of the sleeve protruding from the second chamber engages the seat but if the primary pressure does not exceed the secondary pressure by the predetermined amount, the end of the sleeve does not engage the seat, and fluid escapes from the source through the second channel and communicating sleeve, past the seat.

Abstract: A method and apparatus for the diversion of fluid flow at reduced pressure out of a high pressure fluid delivery system when the discharge of the system is closed. A bypass valve having a movable piston oriented transverse to the flow direction and a slidable seal oriented parallel to the flow direction is located between the system pump and discharge. The movable piston has two working surfaces of different areas which define planes parallel to the flow direction so that the working surfaces and therewith the piston are generally responsive only to static fluid pressure. The slidable seal is responsive to dynamic fluid pressure so that when the discharge is closed and the dynamic fluid pressure thereby reduced, the seal moves to interrupt fluid communication between the two working surfaces of the piston.

Abstract: A hydraulic control device for use in a hydraulic system having a pump supplying fluid from a reservoir to a working circuit. The control device detects leaks in the working circuit by monitoring the level of hydraulic fluid in the reservoir. In the event of a drop in the level of hydraulic fluid beyond a predetermined low level, the control device automatically diverts the fluid output side of the pump to the fluid input side to prevent further loss of fluid in the working circuit and to safeguard against cavitation in the pump due to the low level of fluid in the reservoir. The control device also senses excessive pressure peaks in the working circuit and operates to relieve the excessive pressure peaks by automatically venting a portion of the fluid on the output side of the pump to the reservoir.

Abstract: Apparatus for producing dry compressed air comprises a compressor which delivers air to a dry air storage tank through a cooling coil, a liquid separator comprising a housing having a cavity with a valve controlled tap opening at the bottom thereof, a screening filter and an adsorption filter connected in sequence. A pressure sensitive switch turns off the compressor when a predetermined pressure has built up in the storage tank. When delivery of air ceases, a valve control system opens the tap opening of the separator and second valve control system opens a valve to permit back flow of air from the dry air storage tank back through the adsorption filter to regenerate it and out of the tap opening if the moisture content of air in the dry air storage tank is above a predetermined level.

Abstract: In a refrigeration system comprising a compressor, expansion means, an evaporator and a condenser, the improvement comprising a normally open, spring-loaded valve positioned so that when the compressor is not operating a passage is provided between the compression chamber and the inlet to the compression chamber, and when the compressor is operating the passage is closed.

Abstract: A check valve having a piston with a greater coefficient of thermal expansion than the body which closes a bleeder port at running temperatures and opens the bleeder port when flow stops or when the valve cools. A body of brass and a piston of filled TFE is a preferred combination.

Abstract: A reciprocating compressor including a valve plate mounting a discharge valve to control the flow of compressed gas through an opening formed in the valve plate. The discharge valve is formed from a bimetallic element and is mounted in a normally open position with respect to the discharge opening in the valve plate to permit fluid leakage from the compressor cylinder through the opening upon startup of the compressor. The discharge valve warps to a closed position relative to the opening in the valve plate as the temperature of the gas increases due to the compression thereof by operation of said piston.

Abstract: Rotary apparatus for compressing and discharging fluid within a container. The apparatus includes an oscillating rotor or cam-like projection of substantially constant thickness in the plane of the longitudinal axis of the housing which cooperates with a sliding partition to define multiple compartments into which fluid is introduced during a portion of the rotation of the rotor or projection and is compressed during another portion of rotation of the rotor or projection.

Abstract: The valve has an input end through which hydraulic fluid is introduced and a main output end through which the hydraulic fluid is transmitted to the mechanism which is controlled. Intermediate the input and output ends is a bypass through which the hydraulic fluid can flow back to the sump which flow occurs until a movable piston within the device closes off the bypass.

Abstract: A combination equalizer and over-pressure control for use with fluid compressors comprises a passage having a first piston including a relief port therethrough, the piston when in a first position preventing any flow of fluid through a second relief port. A second piston, disposed upstream of the first piston, is movable relative thereto. A first spring provides a force to maintain the second piston in spaced relationship relative to the first piston, the second piston moving into sealing abutment with the first piston to close the first relief port when fluid pressure acting on the second piston exceeds a predetermined value. A second spring provides a force to maintain the first and second pistons in position relative to the second relief port to prevent any fluid flow therethrough. The first and second pistons move jointly at a predetermined over-pressure condition to open the second relief port.

Abstract: A source of hydraulic fluid is connected with a user by a hydraulic circuit in which a pump is interposed so as to supply the hydraulic fluid under pressure to the user. A housing is interposed in the circuit, having a bore communicating with the circuit. An air venting passage communicates with the bore and a valve body is located in the bore upstream of the passage and defines a throttling gap through which air in the circuit can pass into and out of the passage, but at which subsequent flow of hydraulic fluid will create sufficient pressure to displace the valve body to a position in which it seals the air venting passage.

Abstract: The preferred embodiment of the invention disclosed herein includes a main check valve responsive to the rate of flow of fluid to a demand system and a bypass valve metering the flow of fluid to a bypass system. In the closed position of the main check valve, the bypass valve is in a fully open position whereby a predetermined minimum flow from a pressure source is maintained; in an intermediate position of the main check valve responsive to the predetermined minimum rate of flow thereacross, the bypass valve is closed and remains closed from the intermediate position of the main check valve to the fully open position. Operation of the bypass valve is controlled by fluid pressure from the inlet side of the main check valve which acts on a piston associated with the bypass valve and the buildup of pressure is controlled by a pilot valve.