Abstract: A device for elevating a pressure acting on a liquid including a liquid pressure elevating mechanism for receiving liquid under a first positive pressure and at a selected volume of liquid per unit of time flow rate from a liquid source at an inlet port and supplying the liquid under a second positive pressure substantially greater than the first pressure and at the selected volume of liquid per unit of time flow rate to an outlet port and a liquid utilizing load connected thereto. The second pressure is sufficiently high enough to cause the liquid to become substantially compressed to thereby result in the second pressure to want to vary during intervals of time that the liquid is being compressed. A control device is provided for accommodating the compressibility of the liquid so as to maintain a substantially constant second pressure.

Abstract: An air pressure pump with reversible power cylinder comprises a cylinder, a left cap and a right cap disposed at two sides of the cylinder. A piston passes through the cylinder. An air inlet pipe and two air outlet pipes connect the left cap. A collar has five lead holes. The collar surrounds a movable sleeve. Two ring grooves are formed on the movable sleeve. Two passages are disposed on the left cap. The right cap has a central hole to receive a pump. The pump has a central hole to support a rod. A Second valve seat is disposed at the bottom of the pump. A through hole is in the second valve seat.

Abstract: A double acting pneumatically operated pumping assembly for pumping viscous fluids, especially food stuffs, is provided. The piston has an enlarged central portion integral with reduced diameter end portions. Inspection means, for example vent ports, are provided between seals of each end portion so that any leakage of either pneumatic fluid or of viscous fluid is detectable. The pump is preferably of modular form, each module having flanged ends and hand-tightenable band clamps holding the flanges together for easy assembly and disassembly. A feature of the invention is an operating valve having pilot chambers at each end for control of the spool position. Movement of pilot pistons within the pilot chambers affects the pressure balance between ends of the spool. Changes in pressure may be derived from the piston chamber of the pump from ports located to change the pressure balance of the valve when the pump piston has completed its stroke.

Abstract: An electronic condiment dispenser may dispense a plurality of condiments. The condiment dispenser may include a bag support module for holding a plurality of condiment supply bags. A pump regulator module may be connected to each condiment bag and may pump a condiment from the bag to a manifold diffuser module. The pump regulator module may include a multi-chambered pump having separate chambers for isolating the pump working fluid from the condiment, so the pump working fluid does not contaminate or react with the condiment. A main case may house at least one manifold diffuser module and may be configured to support a tray carrying a large number of food targets, i.e., 6 or 12 food targets, such as hamburger buns or taco shells. A programmable control module may be connected to the pump regulator module for controlling and selectively dispensing a predetermined amount of condiment and/or number of condiments to a predetermined number of food targets.

Abstract: A pump that is in essence leak-proof and prevents the escape to ambient atmosphere of environmentally hazardous fluent materials is comprised of an outlet block defining a pump chamber having a fluid inlet and a fluid outlet, a piston having one end reciprocable within the pump chamber and sealed to the outlet block, a piston rod connected to the other end of the piston for reciprocating the piston, a dynamic block secured to the outlet block and defining a sealed dynamic chamber within which the other end of the piston reciprocates, and an outlet from the dynamic chamber in continuous closed-circuit communication with a recirculating system for preventing escape into the environment of any fluent material that may leak past the piston seal. The pump also includes an articulated seal for sealing the piston rod to the dynamic chamber to maintain the sealed integrity of the chamber while at the same time accommodating reciprocation of the piston rod.

Abstract: A fluid-driven proportioning pump for dispensing precise volumes of at least three different fluids includes a drive cylinder housing a correspondingly formed drive piston which divides the drive cylinder into first and second drive fluid chambers and is propelled in a reciprocating motion by a pressurized drive fluid. The housing for the drive cylinder is comprised of two identical hollow housings mutually matingly engaged at the open ends thereof. The face of the drive piston is provided with projecting proportioning pistons which extend into proportioning cylinders that open into each drive fluid chamber. An over-center mechanism triggered by movement of the drive piston at the extremes of the strokes of the reciprocating motion thereof operates valving that admits the pressurized drive fluid into turn it of the drive fluid chambers. The over-center mechanism is activated by hoop springs and is housed entirely within the drive cylinder.

Abstract: An air driven diaphragm pump having two diaphragms joined by a common control shaft to reciprocate in opposed chambers for pumping material through check valve ported cavities. An actuator valve is associated with the central housing of the pump and includes a valve cylinder within which a valve piston reciprocates. The valve piston is caused to reciprocate by alternate venting of the ends of the cylinder. Enlarged air chamber passages are controlled by the control shaft to vent the ends of the valve cylinder. A cylindrical portion of the control shaft includes axial slots for venting alternate ends of the valve piston. Annular channels manifold air to and from the axial slots.

Abstract: A two stage free piston pneumatically operated air compressor having an integral and coaxial power piston, first stage piston and second stage piston. The discharge of the compressor first stage is the inlet for the compressor second stage. A piston-type throttling valve is used to control the speed of the reciprocating piston. The piston-type throttling valve is responsive to the pressure drop across a fixed orifice.

Abstract: A cushioning means for an intensifier for delivering ultra high pressure water to the cutting head of a water jet cutting apparatus. The intensifier has a power piston and cylinder assembly connected to secondary fluid pumping piston members which extend into pumping chambers located at opposite ends of the hydraulic piston and cylinder assembly, and in a common housing. Inlet poppet valves located in the pumping chambers control the flow of water from inlet passage into the pumping chambers while outlet poppet valves allow ultra high pressure water to be pumped out of the pumping chamber into an accumulator fluidly connected to the cutting head. Hydraulic fluid under pressure is sequentially directed to opposite ends of the piston and cylinder assembly, with the piston and cylinder assembly being provided with cushioning means to assist in smooth deceleration of the piston during each stroke or cycle.

Abstract: A water heater (10) has a pressure-transfer module (20) interposed between an external pressurized-water circuit and the water inside the water-heater vessel (12) so that the water is at atmospheric pressure and can thus have a free upper surface. A shut-off valve in the inlet (14) to the pressure-transfer module (20) is controlled in accordance with the water level as detected by a float (74). If the water level falls below a predetermined minimum or exceeds a predetermined maximum, the shut-off valve closes so as to prevent further flow into the water heater (10) from the upstream side of the exterior circuit.

Abstract: A pump assembly especially adapted for pumping viscous and/or abrasive materials is comprised of a pair of opposed single acting piston pumps operated alternately by an interposed reciprocal actuator, and a static chamber interposed between each pump and the actuator; each pump comprising a pumping chamber having aligned inlet and outlet check valves in its peripheral wall and defining a straight line path of fluid flow diametrically through the chamber, a piston having its periphery spaced from the peripheral wall of the pumping chamber and having a relatively short stroke to maintain the straight line path of fluid flow through the chamber, and an annular seal extending from the peripheral wall of the pumping chamber toward the piston and bridging the gap between the periphery of the piston and the peripheral wall of the pumping chamber, the piston having sealed engagement with the seal throughout its reciprocal path of movement; the static chambers isolating the two pumps and the actuator from one another

Abstract: An intensifier for delivering ultra high pressure water to a cutting head of a water jet cutting apparatus. The intensifier has a power piston and cylinder assembly connected to piston members extended into pumping chambers in housing located at opposite ends of the piston and cylinder assembly. Inlet poppet valves located in the pumping chambers control the flow of water from inlet passages into the pumping chambers. Outlet poppet valves allow ultra high pressure water to be pumped out of the pumping chamber into an accumulator fluidly connected to the cutting head. Hydraulic fluid under pressure is sequentially directed to opposite ends of the piston and cylinder assembly with a solenoid operated reversing valve. Limit switches operable in response to movement of the piston members control the reversing valve. Linear motion transfer mechanisms are moved with ramps on the piston members to actuate the limit switches to control the reciprocating action of the piston and cylinder assembly.

Abstract: A fluid-driven proportioning pump for dispensing precise volumes of at least three different fluids includes a drive cylinder housing a correspondingly formed drive piston which divides the drive cylinder into first and second drive fluid chambers and is propelled in a reciprocating motion by a pressurized drive fluid. Each face of the drive piston is provided with projecting porportioning pistons which extend into proportioning cylinders that open into each drive fluid chamber and being directed toward the drive piston. An over-center mechanis triggered by movement of the drive piston at the extremes of the strokes for its reciprocating motion operates valving which admits the pressurized drive fluid into alternate of the drive fluid chambers. The over-center mechanism is activated by loop springs or preferably by pairs of C-shaped springs, and is housed entirely within the drive cylinder.

Abstract: A bellows-type pump has a plastic bellows interiorly supported by interior pressure. The interior pressure is supplied by a fluid source which passes through a pressure regulator to control the amount of interior pressure exerted on the bellows. A fiber-optic leak detector can be inserted into the plastic bellows to detect the leakage of process fluid therein.

Abstract: Disclosed is a device for converting pressure fluid input of one fluid to pressure fluid output of a second fluid without contaminating either fluid. The transformation is accomplished by a unique H section piston which cooperates the internally protruding endcaps enclosed in a double ended cylinder; the piston having a central control valve which reverses the piston on control pin end of stroke contact. Positive reverse action is obtained by means of endcap plungers which operate in response to piston position and pressure of the one fluid. The device is double acting and is enclosed totally within a single cylindrical module which is compact and inexpensive to manufacture.

Abstract: An improved double acting diaphragm pump utilizes at least one supplemental diaphragm and associated pressure chamber arranged coaxially with the connecting shaft of the main diaphragms. The supplemental chambers are connected via parallel pressure lines or conduits to the pressure source for the main diaphragms and associated pressure chambers.

Abstract: A fluid pressure-intensifying system of the double-acting type has a recompression valve assembly that meters working fluid of the low pressure hydraulic cylinder to control low pressure piston travel upon reversal at the end of each pressure-intensifying stroke.

Abstract: A double-acting diaphragm pump system for pumping and spraying materials, particularly corrosive liquids and abrasive fluids. The system includes a hydraulically driven double-acting diaphragm pmup which is electrically controlled for alternately pumping material through the dual pump chambers to an outlet pipe. The diaphragms of the double-acting pump are moved back and forth by a dual-acting hydraulic cylinder powered by a hydrostatic transmission for providing automatic response to pumped fluid needs, coupled with overpressure protection. An expansion tank maintains a constant pressure on the fluid as it is discharged from the pump. The system is capable of spraying abrasive slurries of a wide variety, at an even spray pattern, as the system wears, and hardened wear rings around the inlet and outlet valves permit the pump to be inexpensively rebuilt after extended use pumping abrasive slurries.

Abstract: An energy recovery system is disclosed for recovering energy of highly pressurized natural gas when it is depressurized prior to distribution. The system includes a processing vessel which defines a bounded volume. The vessel is partially filled with water. A shaft extends through an aperture formed in the processing vessel with the shaft reciprocally moveable through said aperture. A conduit connects the high pressure natural gas to a gas inlet disposed within the processing vessel. The inlet is disposed beneath the level of the water within the vessel. Gas flows from the inlet in a predetermined path toward the water level. An exhaust conduit connects an outlet of the processing vessel to an expansion tank. The outlet is disposed above the water level within the vessel. A lift chamber is connected to the shaft and has an opening disposed to admit gas flowing along the predetermined path. The chamber is sized for gas collected within the chamber to urge the shaft to move toward the water level.

Abstract: An overall pump assembly for smoothly pumping a compressable liquid from a supply is disclosed herein along with two intensifiers which form part of the assembly and a control arrangement for driving the intensifiers in specific phase relationship to one another. Each of the intensifiers includes its own reciprocating piston and a control device interconnected in feedback relationship with the piston in order to follow the latter through its movement. In each of the specific intensifiers disclosed, its piston and control device are interconnected by cable means configured to cause the control device to rotate about its own axis in a manner corresponding to the movement of the piston.

Abstract: A double action diaphragm type pump wherein oppositely positioned diaphragm pumping units are reciprocally operated by a hydraulic cylinder assembly positioned between the pumping units. Separate piston rods extend oppositely from a piston in a hydraulic cylinder, each rod operating a diaphragm in one of the pumping units.

Abstract: A fluid pressure-intensifying apparatus of the double-acting type has an elongated cylindrical housing that encloses the low pressure and high pressure chambers and compressively position and restrains the elements that make up the low and high pressure chambers under operating conditions. Hydraulic working fluid 4-way control valve solenoids are actuated by an actuating piston assembly mounted in fluid communication with the low pressure working fluid chamber.

Abstract: A gas pressure operated proportioning pump is provided including axially aligned and spaced opposed end pumping cylinders and an intermediate drive cylinder provided with centrally apertured opposite end cylinder heads. A piston is reciprocal in the drive cylinder and includes oppositely axially projecting diametrically reduced pumping pistons extending and reciprocal through the cylinder heads in sliding sealed engagement therewith and projecting into the adjacent ends of the pumping cylinders. The pumping cylinder adjacent ends include seal structure slidingly and sealingly engaged with the pumping pistons and the remote ends of the pumping cylinders include check valve equipped fluid inlet and outlet ports.

Abstract: A ratio pump for delivering first and second liquid beverage components in a desired ratio comprising a motor and a pump driven by the motor. The first beverage component is pressurized and is used as the driving fluid for the motor. The second beverage component is pumped by the pump. The first beverage component is exhausted from the motor and delivered along with a second beverage component delivered by the pump. The motor, which may include a piston, requires a predetermined amount of the first beverage component in order to drive the pump to deliver a known volume of the second beverage component.

Abstract: A device for the preparation of a mixture of a basic fluid and at least one additional fluid in a definite mixing ratio is described. The device has a main piston which is movable in a master cylinder between two limit positions. A control unit can feed basic fluid under pressure alternately to one side of the piston and to the other. The main piston is connected to at least one metering piston which is movable in a metering cylinder having an inlet for an additional fluid and an outlet connected to the mixing vessel. In operation, movement of the main piston in the direction which increases the volume of the metering chamber formed in the metering cylinder causes additional fluid to be fed to the metering chamber through its inlet, while movement of the main piston in the opposite direction causes additional fluid in the metering chamber to be expelled through the metering cylinder outlet into the mixing vessel.

Abstract: A hydraulic pressure amplifier, e.g. for generating high water pressure for rock cutting and the like, in which a differentially displaced piston drives plungers alternately to pressurize the water and is driven by a primary fluid under the exclusively of a hydraulically displaceable pilot valve. The valve member is connected by a single pilot passage to the cylinder of the piston for switching between its positions.

Abstract: A hydraulically powered compressor has infinitely variable capacity control through use of a variable displacement hydraulic pump, and a hydraulic control and power system provides the infinitely variable capacity control with a proportionate change in required power. Components may be mounted in an air duct.

Abstract: A positive displacement machine, particularly an internal combustion engine, comprises an oscillating piston connected to a piston pump. The cylinder of the pump is connected through valves to a pressure accumulator and to a substantially pressureless tank. The piston of the motor is integral with the piston of a pump. The valves of the pump are positively actuated by a separate motor.

Abstract: An intensifier pump has a primary fluid cylinder including a primary piston and which has shaft portions received within a separate coaxial fluid chamber. A secondary fluid cylinder having a secondary piston has shaft portions reciprocally received within a separate coaxial fluid chamber. The secondary piston is of a smaller relative diameter than the primary piston. The sizing of the hydraulic pistons in the operating fluid cylinders is used to sequence the pistons in the cylinders with the largest diameter piston being stroked first followed by the second largest diameter cylinder being stroked next, followed in turn by any additional fluid cylinders in the order of the piston diameter size. When the smallest diameter cylinder has been stroked, a pressure switch signals a reverse flow pump to change the direction of circulation of the operating fluid to cycle the pistons.

Abstract: Submergible pumping apparatus for use in an oil or other well comprises, in a self-contained downhole unit, a double-acting reciprocating positive displacement pump for pumping well fluid, a reservoir containing power fluid for operating the double-acting pump, a rotary motor-driven positive displacement pump for supplying power fluid under pressure from the reservoir to operate the reciprocating pump, and a control valve for properly directing high pressure power fluid from the rotary pump to the reciprocating pump and from the reciprocating pump back to the reservoir so as to provide stroke reversal of the reciprocating pump.

Abstract: An engine-compressor comprising a stirling engine which includes a plurality of working cylinders, a plurality of working pistons respectively disposed in the working cylinders for axial reciprocating movements to thereby divide each of the cylinders into an expansion space and a compression space, the expansion space in one of the cylinders being connected through a heating device and a heat accumulating device with the compression space in another cylinder, a plurality of guide cylinders, a plurality of guide pistons disposed respectively in the guide cylinders for axial reciprocating movements, the guide piston being connected through piston rods with respective ones of the working pistons, and a swash plate or a crank device for converting the axial reciprocating movement of the guide piston into a rotating movement; a compressor including compression chambers defined in respective ones of the guide cylinders by the guide piston, intake valves provided in the compression chambers for admitting air thereto

Abstract: A pump is provided for circulating drilling fluid and the like into a well during a well drilling process. The pump comprises a pair of double-ended piston assemblies hydraulically reciprocated in opposite directions by a common hydraulic drive arrangement, wherein each piston assembly has a relatively large piston at one end and a relatively small piston at an opposite end. The various pistons reciprocate within appropriately sized cylinders each having a working end with a one-way intake valve through which drilling fluid is drawn from a supply tank and a one-way discharge valve through which drilling fluid is discharged to the well.

Abstract: A teat spray system for installation in an automatic milking parlor for spraying the teats of cows. The system comprises a differential vacuum line switch, powered from the milking parlor vacuum line, and providing alternating vacuum pulses in a pair of vacuum lines; a liquid disinfectant pressure pump powered from the pair of vacuum lines; a pressure bottle for holding a volume of disinfectant under pressure and a spray line and spray head. The system is pressure self-limiting and has a pressure release valve operative when the milking parlor vacuum line is shut down.

Abstract: A pumping method, principally for oil, allows the sucker rod to fall under gravity for the first part of the downward stroke, then decelerates the sucker rod to a slow rate of descent, so creating a pause in the sucker rod's motion. Shock-absorbing means are provided to eliminate the impulsive loadings imposed upon the sucker rod at either extremity of its motion in conventional pumping methods. Hydraulically and mechanically-driven apparatus is disclosed for carrying out the method.

Abstract: The invention concerns a three- or four-stage gas compressor comprising two interconnecting compression units operated by hydraulic pistons; the first unit comprises a central hydraulic section flanked by two identical and symmetrical lateral sections each incorporating the first and third stages and operated by an alternating hydraulic piston; the second unit comprises a central hydraulic section of lesser diameter than that of unit one but with equal volume of oil, and two lateral sections similar to those of unit one but of lesser diameter. In the four-stage embodiment the lateral sections of unit two comprise between them the second and fourth compression stages, while in the three-stage embodiment the lateral sections of the second unit comprise only a single section each of the second compression stage. The oil chambers relative to each unit's central section interconnect--in either embodiment--by way of a compensating valve.

Abstract: An improved injector pump (10) is the subject matter of this application. The pump (10) includes a piston (44) freely disposed for reciprocation within a chamber (32). The piston (44) has an aperture (62) extending axially therethrough. A valve member (96) is disposed within the aperture (62) for rotation therein. Means are provided for rotating the valve member (96) between first and second positions, and operating fluid is channeled to opposite sides of the piston (44) depending upon the position of the valve member (96). Means (114, 118, 122, 124) are provided to move the valve member (96) between its first and second positions. Plungers (50, 52) extend in opposite axial directions from the piston (44) to effect pumping of the product fluid.

Abstract: A mixing pump includes a primary pumping chamber opposed by a secondary mixing chamber with primary and secondary pistons that are connected to each other and reciprocated in the chambers. Preferably, an actuator mechanism that drives the pistons is located between the chambers. An additive fluid is expelled from the secondary chamber through a mixing conduit into a mixing chamber where it is injected into a main fluid. The fluid mixture from the mixing chamber is then admitted to the primary pumping chamber from which it is expelled under pressure, preferably through an outlet valve in the primary piston. The fluid can be more thoroughly mixed as it passes through that valve and an annular passage surrounding this piston.

Abstract: A hydraulic drive system operating from the periodic pressure wave produced by a Stirling engine along a first axis thereof and effecting transfer of power from the Stirling engine to a load apparatus therefor and wherein the movable, or working member of the load apparatus is reciprocatingly driven along an axis substantially at right angles to the first axis to achieve an arrangement of a Stirling engine and load apparatus assembly which is much shorter and the components of the load apparatus more readily accessible.

Abstract: A free piston compressor for gases and liquids in which the positive pressure of the incoming fluid holds the piston against the piston rod during the intake stroke. In a specific form, the cylinder head is a plug of larger diameter than the piston which can be unscrewed to permit removal and replacement of the piston for service.

Abstract: A pump system includes a source of fluid under pressure conveyed into a fluid chamber containing meshing gears which are rotated by the pressurized fluid to, in turn, transmit rotation to a unitary valve member positioned in a housing. Rotation of the gears also displaces fluid at a preselected flow rate through an inlet port of the housing and into a first inlet port of the rotary valve member. During the first one half cycle of rotation of the rotary valve member, fluid is conveyed through a first set of aligned outlet ports of the valve member and the valve housing to a water pump for displacing a water piston. The water piston is displaced to convey water through a first conduit. During the second one half cycle of rotation of the rotary valve member, fluid is conveyed through a second set of aligned outlet ports of the valve member and the valve housing to displace the water piston in an opposite direction to convey water through a second conduit.

Abstract: A double acting hydraulically driven gas compressor using a free floating piston the reciprocating action of which is being controlled by a valve system responsive to pressure peaks, generated in hydraulic system on piston reversal, the pressure level of those peaks being higher by a constant pressure differential than the discharge pressure of the gas compressor.

Abstract: A pumping system for delivering unstable fluids under pressure, comprising a pair of alternately operated single-acting pumps operated by a double-acting air motor. The air motor is controlled by a reversible spool valve and mechanically operated air pilot valves. The single-acting pumps deliver and contain relatively small quantities of the unstable fluid to a positive flow metering system for connection to an outlet to spray guns or other equipment using the fluid. The metering system includes a metering valve, a flow meter and a bypass valve for removing trapped air and presetting flow.

Abstract: A downhole oil well hydraulic pump has a reciprocating piston assembly with a piston ring mounted in a groove around the piston. This piston ring groove has a main portion which loosely mounts a piston ring and an auxiliary portion joining the main portion which accumulates well fluid to lubricate the piston ring during operation of the pump.

Abstract: A small diameter fluid-driven pump for subterranean fluid sampling, and including an elongated cylindrical body formed by a centrally disposed control valve block assembly and a pair of hollow motor piston chambers on opposite sides of the valve block and joined thereto. Within the centrally disposed control valve block assembly in axial alignment with the motor pistons are a spool pilot valve and a spool fluid distribution valve. The spool pilot valve is constructed to obviate stalling during its reciprocation under the impress of a power fluid directed thereto, and it functions to control the shifting of the distribution valve to which it is internally connected within the valve block assembly.

Abstract: A two-stage pump is illustrated of the type employing a piston having two diameters, one capable of providing a large volume of fluid flow at low pressure so as to move a fluid operated press rapidly until a load is encountered, at which time fluid is delivered at a low volume at high pressure for operation of the press wherein the flow control means are positioned in a piston housing independent of the piston.

Abstract: A double acting concrete pump having a pair of interconnected mud pistons driven by a reversing hydraulic actuator, which is reversed by the piston motion at the end of each stroke, and has a pressure relief to avoid bottoming at the end of a stroke. The mud pistons slide in cylinders which are lubricated and cleaned by a supply of lubricant circulated between the cylinders by the piston action. Concrete or similar mud-like material is drawn from a hopper and pumped out through a common outlet.

Abstract: A hydraulic pump assembly having a motor actuated by a source of fluid under pressure and in turn actuating a fluid pump under the control of a valve responsive to operation of the motor. The diameter of a piston of the pump is smaller than the corresponding diameter of a piston of the motor in order to permit the pump to obtain higher output pressures than are required to actuate the motor. The valve includes a valve element connected directly to the piston of the motor and slidably disposed in a pair of axially spaced, cylindrical housing parts so as to sequentially place ports provided in spaced ends of the valve element in communication with passages provided in the cylindrical housing parts.

Abstract: A reciprocating, fluid operated pump, which is reversed at opposite ends of its travel by shifting of a directional valve, is characterized by a control valve for rapidly and completely shifting the directional valve.In the disclosed embodiment, the pump includes a pair of pumping portions each operated by a respective reciprocating air motor. The air motors are coupled for conjoint reciprocation, and the directional valve alternately applies compressed air to one and then to the other of the air motors. The arrangement is such that when air is applied to one of the motors fluid is forced from its associated pumping portion to an outlet from the pump while fluid is drawn into the other pumping portion from an inlet to the pump, and when air is applied to the other of the motors fluid is forced from its associated pumping portion to the outlet from the pump while fluid is drawn from the pump inlet into the one pumping portion.

Abstract: In a blood dialysis system a proportioning pump accurately mixes precise quantities of water and concentrate. A double-acting piston assembly is disposed in a stepped cylinder which has proximity sensing switches at both ends thereof. These are operated as the piston assembly reaches the end of its stroke in each direction. The switches alternate a bistable solenoid valve system which directs pressurized water to opposite sides of a large central piston, thus causing the piston assembly to reciprocate. Small pistons, attached on opposite sides of the large piston, move in small pump chambers, with check valves. The small pistons pump concentrate in a precise ratio to the volume of water driving the large piston.

Abstract: A fluid-actuated, such as a pneumatically actuated, hydraulic pump of either the single acting or the double acting type is controlled in its operation by a main valve member which has two connecting compartments the fluid in one of which is always at the atmospheric, and in the other always at a superatmospheric, pressure. The main valve member has two end faces, one larger than the other, the smaller being always acted upon by the superatmospheric pressure of the fluid and the larger one intermittently. An auxiliary valve member controls the admission of the pressurized fluid to the larger end face and is open only during the reversal of the hydraulic pump from suction to pumping stroke, while the pressure acting on the larger end face is relieved during reversal from the pumping to the suction stroke. A duct communicates one or the other of the connecting compartments of the main valve member which an actuating compartment of an actuating unit, depending on the position of the main valve member.