Abstract: A portable motor pump of the type in which a pump section driven by a motor is installed inside a liquid chamber, with a discharge port of the pump section being opened into the liquid chamber, and in which water which is to be pumped is led from the outside of the liquid chamber to a suction port of the pump section and the pumped water is discharged from the liquid chamber to the outside is disclosed. The liquid chamber is defined by a motor pump body, a pump outer casing outwardly spaced from and surrounding the motor pump body, a motor head cover covering an upper opening of the pump outer casing and a bottom plate covering a lower opening of the pump outer casing. A circulating water suction port for self-priming of the motor pump is opened into the liquid chamber. A suction port which communicates with the suction port of the pump section and a discharge port for discharging the pumped water to the outside are provided in the motor head cover.

Abstract: A rotary hydraulic vane pump includes a rotor mounted within a housing, with a plurality of vanes individually slidably disposed in corresponding slots in the rotor periphery. A cam ring surrounds the rotor within the housing and has a radially inwardly facing vane track defining as least one arcuate fuel pressure cavity between the rotor and the cam ring. A fuel inlet in the housing includes a primary inlet port opening into the cavity at the leading circumferential edge of the cavity with respect to the direction of rotation of the rotor within the housing. A pump outlet includes an outlet port that opens into the cavity adjacent to the trailing circumferential edge of the cavity. A secondary inlet port opens into the cavity circumferentially between the primary inlet port and the outlet port, and is directly connected to the pump outlet port such that fluid at outlet pressure is available at the secondary inlet port.

Abstract: Valve and channeling improvements in a filter pump head assembly used for dispensing photoresist in a semiconductor manufacturing facility.

Abstract: A fuel pumping apparatus includes a high pressure pump and a low pressure pump contained in a housing and driven by a drive shaft which is coupled to a rotary part of an internal combustion engine. The low pressure pump is a vane pump having a rotor in which is formed a plurality of outwardly extending slots which accommodate outwardly spring loaded vanes. The edges of the vanes engage an eccentrically disposed surface formed on a stator. The pump has end plates and inlet and outlet ports communicating with the space defined between said surface and the outer surface of the rotor. The outer edges of each vane are formed with grooves which extend along the edges and the grooves communicate by way of passages with the inner ends of the respective slots.

Abstract: A plunger of a plunger pump is formed with an air vent passageway having its one end open to a compression chamber and the other end adapted to communicate with a reservoir space open to the atmosphere when the plunger comes near its top dead point. Air or gas trapped in the liquid sucked into the compression chamber will flow into the air vent passageway so as to be discharged into the reservoir space when the passageway gets into communication with it. Since air or gas is removed from the compression chamber, the pumping efficiency is prevented from decreasing.

Abstract: Water is pumped from a container to a refrigerator ice maker and/or chilled water unit. The apparatus for transferring the water includes a motor operated pump, and the motor includes a pair of switches in series for turning the motor off. The switches include a pressure switch actuated from water pressure in the pumped water line and a switch to indicate when the water level in the container is at or below a certain, predetermined minimum. A check valve is in the pumped water line between the pump and the pressure switch to prevent loss of pressure in the line due to the bleeding of pressure through the pump that could otherwise cause the pump to start pumping water when there was no demand for it from the refrigerator.

Abstract: A liquid feed pump system having a pump for feeding a liquid stored on the suction side thereof to the discharge side, resisting a flow resistance from a discharge-side flow resistance element. A first passage connects the flow resistance element and the pump, and a second passage is formed in the first passage. The second passage has a gas-flow resistance smaller than that of the flow resistance element. At the start of pump operation, gas in the pump is quickly discharged through the second passage, so that the liquid can be fed without a delay. The second passage may be an orifice, which is bored through the wall of the first passage and opens to the atmosphere at all times, or a by-pass, which makes a detour around the discharge-side flow resistance element and continually connects the upper and lower courses of the resistance element.

Abstract: Fuel supply systems incorporating fuel pump assemblies having vents leading from upper portions of filter cases to vapor phase portions of a fuel tank. In one embodiment, a fuel pump is located wholly within a filter case with a relief port also provided within the case. Location of the components and baffles as well as a vapor vent promote flow of entrained vapor in the fuel away from the pump intake. Further, with the present arrangement, vapor is less likely to be formed.

Abstract: A liquid dispensing unit is described. The unit includes a first valve element that is held within a liquid passageway by a first spring mechanism. This spring mechanism is designed to yield under pressure to allow the first valve element to move off a valve seat in the opening to allow liquid to pass through. In order to allow air that is trapped on the downstream side of the valve element to escape, air vents are provided in the first valve element. A second valve element is held under compressive force by a second spring over air vents located in the first valve element.

Abstract: A tube shaped sleeve apparatus which includes two cylindrical components adapted to be connected to each other and sections of tubing string by cooperating threads formed at the ends thereof. At spaced intervals in the periphery of the sleeve are a plurality of radial holes or ports and formed in the sleeve bore at opposite ends thereof are stops shoulders. Adapted to be inserted in slidable relation inside the bore of the tubing sleeve is a mandrel which includes a plurality of resilient O-rings or gaskets that are secured in the periphery of the mandrel inside annular grooves formed therein. Formed in the bore of the mandrel and at opposite ends thereof are a second set of stop shoulders. When positioned opposite the holes in the sleeve, the periphery of the mandrel and the gaskets form a tight seal with the wall of the sleeve bore to prevent fluids and gases from the well bore from entering and escaping the tubing sleeve.

Abstract: An apparatus for supplying an accurately measured volume of liquid, comprising a vessel filled with the liquid, a cylinder loosely and slidably fitted into the vessel from above, and a sealing box at the top of the vessel sealing the vertical motion of the cylinder. The sealing box has a liquid discharge port at a bottom edge. A drive shaft, preferably screw driven, moves the cylinder vertically downward.

Abstract: An air-water separator used in a water well upstream of the intake on a submersible pump comprising a collar member positioned between the well casing and the water pipe including a plurality of spring-biased check valves in the collar which allow gravity flow through the collar only after a certain static head of water is built thereabove to allow sufficient time for the air bubbles to separate from the water before intake into the pump.

Abstract: A manually actuated dispensing pump having a pump body extending transversely above a closure cap adapted for mounting the body at the upper end of a container, has an outwardly open pump cylinder for the reception of a reciprocable piston having spaced piston seals. To facilitate pump priming, the inboard seal is positioned relative to the inlet port so that the inboard seal overlies the inlet port at a predetermined position during the inward pressure stroke of the piston to permit flow of entrapped air from the pump chamber outwardly of the pump cylinder via the annular chamber defined between the piston seals.

Abstract: An evacuating device for a plunger molding apparatus including a material cylinder for receiving a blank to be extruded, a ram head slidably engageable in the material cylinder, a hydraulic plunger having a piston connected to the ram head, an evacuating cap provided slidably in an air-tight manner on the piston and having evacuating pipes, and a blowdown valve provided in the ram head for closing and opening an air blow aperture formed in the ram head. The ram head has a flat surface which is in contact with the blank in the material cylinder. An O-ring is arranged in the flat surface of the ram head about the air blow aperture. The blowdown valve consists of a stem and a head which is brought into contact with the flat surface of the ram head through the O-ring when the ram head is being advanced, thereby improving the air-tightness between the ram head and the blowdown valve to prevent the ceramic batch from entering the air blow aperture.

Abstract: A downhole pump having a gas release probe which probe can be easily applied to a conventional travelling barrel downhole pump by merely lengthening such barrel by providing a variable length spacing sleeve above the travelling valve. The trip rod of the probe lifts off the valve element of the valve from its valve seat to release any gas or foamy oil otherwise trapped between the lower standing valve and the upper travelling valve of the pump. The invention is useful for obtaining oil under subterranean formation conditions that do not normally permit such recovery efficiently due to gas locks and can be either provided in a downhole pump or added to a preexisting pump.The term variable length spacing sleeve is used to describe a spacing sleeve whose length is established to suit a particular operating environment, and which length is determinable by one skilled in the art after considering the various operating parameters of the oil well in question.

Abstract: Oil and other fluids are pumped from a well drilled into chalk or other difficult-to-produce formations by applying a back pressure to the formation concurrently with pumping fluid from the formation. One embodiment a pump suitable for performing the method includes a reciprocating piston with a check valve to permit the passage of fluid through the piston during downstrokes and to prevent its passage during upstrokes. The pump also includes a second check valve having a telescoping link that permits the downward passage of fluid for a first portion of the downstroke of the pump piston but prevents the passage of the fluid during a second portion of the piston downstroke. The combined action of the two valves is to lift fluid on the pump piston upstroke and force a portion of the previously lifted fluid back into the well, and thus into the formation, during the first portion of the downstroke.

Abstract: An automatic lubricator for chain conveyors with a pivoting arm having a roller contacting the chain and moving between the chain side links to place lubricating nozzles along the chain center line. A magnetic proximity sensor on the pivoting arm activates the fluid pump when the nozzles are in position to deliver lubricating fluid to the chain pins. Improved metering pump apparatus diverts fluid from the metering pump to a fluid return line immediately at the end of a lubrication cycle. The metering pump chamber is then primed for the next cycle. Drippage from the lubrication nozzles is eliminated.

Abstract: A portable engine-pump assembly for use in firefighting applications is constructed of a high-speed, lightweight engine and a double-suction pump. The engine is arranged with a vertical crankshaft for driving the pump which is mounted adjacent thereto with a vertical pump shaft coupled to the crankshaft. The assembly is designed to provide high lift, high efficiency and a steady high flow volume and to be compact and light in weight.

Abstract: Pump apparatus and method in which gaseous fluids that develop in the pumping chamber of a down hole pump can be removed during normal operation of the device to prevent gas-lock and to avoid having to force gases up the tubing string.

Abstract: A fuel tank mount for in-tank electric fuel pumps to reduce noise and vibration which includes a sealed outer shell spaced from the elongate housing of the fuel pump and supported in and isolated from the pump by resilient seals. The fuel pump and surrounding shell are supported on a fuel tank top closure. One modification utilizes a wire support. A second modification utilizes a direct mount to the top closure. A vapor by-pass is disclosed for one embodiment which closes in response to liquid fuel under pressure.

Abstract: A downhole pump having a gas release valve which valve can be easily applied to the fixed barrel of a conventional downhole traveling plunger pump by merely lengthening such barrel. A trip on the pull rod attached to the plunger lifts off a valve element of the barrel valve seat to release any gas or foamy oil otherwise trapped between the lower standing valve and the traveling valve of the plunger. Such release takes place on each stroke of the pump. The invention is useful for obtaining oil under subterranean formation conditions that do not normally permit such recovery efficiently due to gas locks and can be either provided in a downhole pump or added to a conventional traveling plunger preexisting pump.

Abstract: A method and apparatus for pre-charging the pump chamber of a discharge pump on a container such as a fluid atomizer primes the pump for dependable operation thereafter. The method includes opening the outlet valve of the discharge pump by operating the pump to its full displacement, and applying a vacuum to draw container contents into the pump chamber, just up to the outlet valve. The apparatus for practicing the method includes a controllable vacuum head adapted to engage an outlet channel of the container, the vacuum head also being movable to engage and move the pump. The apparatus can incorporate an indexing feeding arrangement for delivering articles to the vacuum head, and a blast of pressure may be applied upon completing the process, to release the containers from the vacuum head and securely close the pump outlet valve.

Abstract: A method, system and apparatus is disclosed for pumping liquid from a well such that vapor lock of the pump cannot occur due to gas or steam and such that the pump strokes only in response to the production rate of well liquid. The pump can be used for lifting heavy oils heated by steam floods or the like as well as for pumping liquids from conventional wells. Reduced pump wear, reduced energy requirements, reduced maintenance and the automatic adaption to changing well production rates are among the objects of this invention.

Abstract: An improved intravenous metering device (1a) having a measuring chamber (77) for use in measuring the discharge pressure of fluid exiting the device (1) is disclosed. The discharge pressure measuring chamber (77), which operates in conjunction with a pin (63) and flexure beam (65) arrangement to provide an indication of fluid discharge pressure, is incorporated into the fluid flow path through the device in order to permit sweeping of gas bubbles from the chamber (77) during device priming operations. Thus, complete removal of gas bubbles from the device (1a) prior to employing the device with a patient is more easily attainable.

Abstract: A fuel pumping apparatus for supplying fuel to a compression ignition engine includes a low pressure pump having an outlet connected to an air/fuel separation chamber. The chamber is connected to a high pressure pump through a passage. Fuel is supplied to an inlet of the low pressure pump through a first passage formed in a rotary part of the apparatus, the passage extending into a cavity in the apparatus. A fuel supply passage connects with the cavity and a second passage connects the upper part of the cavity with the fuel inlet of the low pressure pump. The second passage incorporates a non-return valve. Air in the cavity is directed by vortex action to the first passage and can be drawn into the low pressure pump and expelled from the separation chamber through a restricted outlet. If too much air collects in the cavity air will be supplied to the high pressure pump and will cause irregular operation of the engine.

Abstract: A valve arrangement for venting conduits in pumping systems having several pumping units for delivering a gas or vapor generating liquid includes a double-seat valve in which the valving element moves between two extreme closing positions and an intermediate position in which the venting conduit is momentarily open; as the venting conduit is connected at one end with the gas collecting zone in one pumping unit and at the opposite end with the liquid discharging zone below the delivery valve so that the double seat valve is automatically controlled by the pressure difference resulting due to different operational phases of the pumping system.

Abstract: A fuel injection pump of the rotary distributor type has a main pumping chamber including a bore in which is located a plunger and an auxiliary pumping chamber including a further bore and a further plunger. Speed responsive valve means is provided which connects the two bores together for starting purposes. In order to permit air to escape from the bores a spill passage is connected by a passage to the further bore and the spill passage is brought into communication with a spill port while fuel is being supplied to the bores.

Abstract: A device for precise metering of liquids for intravenous delivery to a patient and its method of use, the device including a pumping chamber with a reciprocable diaphragm positioned therein such that the cross-sectional area of the liquid flow path through this chamber is approximately equal to the cross-sectional area of the inlet and outlet of the chamber. The device also includes check valves positioned at the pumping chamber inlet and outlet and a gas retention chamber having an upper portion providing for the formation of the gas-liquid interface and a lower portion from which liquid free of gas bubbles may be removed.

Abstract: The invention relates to a method of removing air or gas bubbles tending to collect in the "dead space" of a piston burette or another liquid dosage piston pump during operation thereof. The venting is performed by sucking a substantial volume of air into the pump cylinder in addition to a certain amount of liquid, and the air and part of the liquid within the pump cylinder is thereafter discharged therefrom. A piston dosage pump for carrying out this method comprises a valve mechanism by means of which the pump cylinder may be selectively communicated not only with a liquid inlet conduit and a liquid outlet conduit, but also with an air inlet passage.

Abstract: A liquid fuel pumping apparatus includes a plunger and a piston which together are moved inwardly by cam means to deliver excess fuel for starting an engine, the plunger only being effective to supply fuel to the engine when the latter has attained a predetermined speed. The piston constitutes a valve to permit fuel and any air contained within the cylinder to escape from the cylinder during the initial inward movement of the piston.

Abstract: A fuel pump assembly is designed for mounting in the interior of a vehicle fuel tank. The assembly includes a reserve tank and a fuel pump mounted within the reserve tank with a noise dampening cylindrical intermediate layer. An intake chamber is formed by a filter screen which is mounted in the reserve tank surroundng the inlet of the fuel pump. A vent channel is provided bypassing the intermediate layers and connecting the intake chamber with a vent conduit for venting gases from the intake chamber of the fuel pump.

Abstract: A centrifugal pump driven by a tractor draws material, as liquid manure, through a suction hose and discharges the material into one of two discharge hoses. A first discharge hose directs the material back into the source of material to agitate and mix the material. The second discharge hose is used to deliver material from the pump to a transport tank spreader. The pump has a housing rotatably supporting an impeller. A cone-shaped member connects the inlet side of the housing to the suction hose. The inlet end of the suction hose has a one-way door valve which allows the material to move into the suction hose and restricts reverse movement out of the suction hose. The inlet end of the suction hose has an exit opening closed with a movable cover. The cover can be moved to an open position so that material in the suction hose can drain back into the holding area. A primer pump mounted on the housing is operable to prime the pump with fluid.

Abstract: An electromagnetic pump particularly adapted for use with oil burners is disclosed. The pump embodies an armature that is reciprocated by a magnetic field produced by an electromagnetic coil. The armature drives the piston of a piston pump that is adapted to pump a liquid at low volume and high pressure. The pump also embodies a diaphragm disposed in a chamber having an inlet portion on one side of the diaphragm and an outlet portion on the other. The inlet portion of the chamber is connected to a liquid supply line leading to the pump and the outlet portion is connected to the discharge of the piston pump and also to a valve-controlled vent leading to atmosphere. The diaphragm is moved in one direction only by the armature and in the opposite direction by a spring. When there is air in the liquid supply line, the vent valve is opened and the diaphragm rapidly pumps air to the atmosphere. When liquid is discharged from the vent, the valve is closed.

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 reciprocating adjustable stroke positive displacement fluid pump is provided with an expandable chamber driven in the displacement or feed direction by an eccentric drive acting through a driven member. The eccentric drive moves the expandable chamber to its limit of excursion in the displacement or feed direction. Adjustment means cooperating with stop means limits the excursion of the driven member and the expansion of the expandable chamber in the suction or intake direction so that the amount of fluid pumped is continuously adjustable from no volume to the capacity of the expandable chamber by positioning the stop means. The pump is further provided with means for driving a plurality of individually adjustable pumps from the same drive motor and with means for equalizing the load on the pump motor.

Abstract: A motor fuel pump comprises a motor unit, a pump unit and a common driving shaft. The pump housing of the pump unit has a frustum-shaped ceiling with a central opening at the top thereof. The pump impeller has a flat member to which a plurality of outwardly extending blades are secured. Since the central opening of the frustum-shaped ceiling is approximately equal to the fringe of the flat member and opens therebove, vapor generated from the fuel in the pump housing is readily evacuated from the pump housing and cavitation may be prevented.

Abstract: A fuel pump assembly is designed for mounting in the interior of a vehicle fuel tank. The assembly includes a reserve tank and a fuel pump mounted within the reserve tank with a noise dampening cylindrical intermediate layer. An intake chamber is formed by a filter screen which is mounted in the reserve tank surrounding the inlet of the fuel pump. A vent channel is provided bypassing the intermediate layers and connecting the intake chamber with a vent conduit for venting gases from the intake chamber of the fuel pump.

Abstract: An improved pump and motor assembly is utilized to regulate a flow of fuel to an internal combustion engine. All of the fluid connections to the pump are connected with one end of the assembly. The pump and motor are both enclosed within a one-piece casing having a tubular side wall which is integrally formed with an end wall. The end section to which all of the fluid connections for the pump are made, is connected across the open end of the tubular side wall. To provide for the removal of vapor bubbles from the fuel, fuel supplied under pressure from the tank flows through an inlet cavity which circumscribes the pump and has an axial extent which is equal to the length of the pump. In addition, a screen at the inlet of the pump itself blocks the flow of vapor bubbles from the inlet cavity to the pump. The forces applied against opposite sides of the moving components of the pump by the inlet fluid are substantially balanced.

Abstract: A method for the ventilation of fuel supply pumps as well as a new type of fuel supply pump are proposed which, particularly in pumps having two pumping stages coupled in series within the housing, serve to secure the ventilation of the first pumping stage. Preferably the first pumping stage is embodied as a lateral channel pump which has a forward anterior base plate. The ventilation bore is arranged axially at first in the base plate and in association with the lateral channel and is preferably formed during manufacture in one piece with the base plate; a reduction of the overly-large diameter of the ventilation bore is effected by the insertion of a reduction part to achieve the flow cross section required for ventilation. The ventilation to the outside of the lateral channel stage takes place via an external connection nozzle on the pump housing, which is secured thereon either axially or radially and can be embodied in one piece therewith as necessary.

Abstract: In pumping LNG (liquefied natural gas) from one receiver to another, e.g. from a vessel's tank to a shore installation, it is conventional to use a submerged pump, a riser pipe connecting the pump to a stop valve and flexible joint connecting the stop valve to a header. If a pocket of gaseous LNG is present in the riser pipe, when the pump commences its operation, the advancing column of liquid in the riser pipe slams against the stop valve and may damage it. The invention provides the improvement of a removable or bypassable flow restrictor incorporated between the pump and the riser pipe, permitting to ensure that the riser pipe is completely liquid-filled, before the pump commences to operate.

Abstract: Disclosed is a constant pressure spraying apparatus in which the motor driven pump piston moves within a pump housing and valve assembly which are carried by a cap or closure for the fluid tank forming the reservoir of fluid to be pumped and sprayed. The cap structure is shaped so as to provide a drain sump for fluid leaking past the pump piston.

Abstract: A liquid cryogen pump in which liquid is maintained on both sides of the pump piston during operation. In the preferred embodiment, vapor, when present in the pump chamber, is passed from in front to behind the piston by providing a predetermined clearance between the piston and the cylinder in which it is reciprocated. The clearance is preferably large enough to pass enough liquid cryogen to maintain the desired head of liquid behind the piston. In the embodiment set forth, the pump is arranged so that it can be immersed in the liquid cryogen to be pumped with its pumping chamber and valves at or close to the bottom of the liquid cryogen supply. Heat transfer between the warm, upper end of the pump and its cold end is effectively restricted, and, preferably, the warm end is connected to the cold end of the pump by thin-walled tubular members formed of low thermal conductive materials to minimize heat transfer by conduction.

Abstract: A cassette is described for use in an intravenous delivery system having a pump. The volume of a main chamber defined by the cassette body is varied by a membrane in a wall thereof while unidirectional inlet and outlet valves maintain the direction of fluid flow into and out of the main chamber. A prechamber is positioned above the inlet port in order to accumulate air from the upstream portion of the intravenous delivery system in which the cassette is used.

Abstract: A cassette is described for use in an intravenous delivery system having a pump. The volume of a main chamber defined by the cassette body is varied and unidirectional inlet and outlet valves maintain the fluid direction into and out of the main chamber. In the operating position of the cassette, the outlet valve is positioned to be in communication with any gas present in the main chamber. For the purpose of accumulating air from the upstream portion of the intravenous delivery system in which the cassette is used, a prechamber is positioned above the inlet port communicating therewith.

Abstract: A hand-held pipette with a liquid dispensing knob at one end operably connected therewithin to a piston and piston cylinder assembly at the opposite end that is detachable from the pipette body for cleaning or replacement. An internal pawl and rack mechanism causes the piston to advance a small amount each time the knob is pressed, thereby repetitively dispensing small volumes of liquid therefrom. A second knob cooperatively engages an internal mechanism for both urging the piston to an overshoot position within the piston chamber and to disengage the piston from the internal mechanism in the pipette housing.

Abstract: A hand-held liquid dispenser of the type using a piston and piston cylinder for precise dispensing of desired volumes of liquid, including an improvement that automatically eliminates any air from the piston cylinder when an operator normally fills the piston cylinder with the desired liquid. A second piston of larger diameter than the first is disposed to draw fluid through the piston chamber at a much faster rate during a first short segment of an intake stroke than would the first piston, thereby to exhaust all dead air from the cylinder and fill it entirely with liquid.

Abstract: A reservoir is provided in the inlet line to a pump in which air and vapor collects. The air and vapor is drawn out by a fuel operated pump and supplied to a fuel/air separator. Fuel passes back to the inlet line and the air and vapor is allowed to escape.

Abstract: A pump mechanism for pumping ink or similar writing fluid from a fluid reservoir to a writing device. A piston is moved in a cylinder in one direction to draw ink into the cylinder from a reservoir through a capillary tube, and is moved in an opposite direction to discharge the ink to a writing device while at the same time, in cooperation with a flexible membrane located in the cylinder and connected to the piston, to discharge any air in the capillary tube back into the reservoir.

Abstract: A dispensing pump having upper and lower pistons defining opposite ends of a two diameter pump chamber, the volume of which is varied by movement together of the pistons, while a small amount of relative movement of the pistons, resulting from pressure changes within the pump chamber, effects opening and closing of the discharge valve. For facilitating the priming of such a pump, the lower piston and cylinder are arranged to define a normally closed priming valve operable at a predetermined point in the lower piston stroke to permit reverse flow of entrapped air from the pump chamber into a liquid supply container with which the pump is associated.

Abstract: A flow system for infusing a fluid such as blood from a storage reservoir into the human body includes a hand-operated pump for increasing the flow rate of the fluid through the system when required. The pump includes a duckbill-type valve assembly user-conditionable to an open position wherein fluid can pass freely through the valve and air trapped in the housing of the pump can be purged upline to the reservoir, and to a closed position wherein reverse flow of fluid in the system is prevented during operation of the pump.