Abstract: A compressor comprises a suction passage; an oil reservoir for storing a lubricating oil which is separated from a refrigerant gas having a discharge pressure; and a throttle valve provided in the suction passage and having a valve body for adjusting an opening degree of the suction passage based on a differential pressure applied to the valve body. The suction passage has an upstream suction passage which is located upstream of the throttle valve. The compressor comprises a lubricating oil passage connecting the oil reservoir to the upstream suction passage for the lubricating oil in the oil reservoir to flow to the upstream suction passage therethrough.

Abstract: A pump assembly having a power end and a fluid end, wherein the fluid end includes a plurality of pump bodies connected side by side between opposing end plates with a plurality of fasteners tightened to compress the pump bodies between the end plates. The power end and at least one of the plurality of pump bodies being connected together by a tie rod having a rod portion and a sleeve portion, wherein the sleeve portion surrounds the rod portion and abuts the power end at an end and at least one of the pump bodies of the fluid end at an opposite end.

Abstract: A combination compressor and vacuum pump apparatus comprising a common drive mechanism, a compressor piston-cylinder unit mechanically coupled to the drive mechanism, the compressor piston-cylinder unit comprising a hollow first piston rod connected to the drive mechanism at a first free end substantially opposite a first piston operable within a first cylinder so as to form the compressor piston-cylinder unit, and a vacuum pump piston-cylinder unit mechanically coupled to the drive mechanism, the vacuum pump piston-cylinder unit comprising a hollow second piston rod connected to the drive mechanism at a second free end substantially opposite a second piston operable within a second cylinder so as to form the vacuum pump piston-cylinder unit, whereby air is pulled into the compressor piston-cylinder unit through the first piston rod for compression therein and air is exhausted from the vacuum pump piston-cylinder unit through the second piston rod.

Abstract: In at least some embodiments, a pump includes a turning member and a reciprocating member coupled to the turning member, the reciprocating member performing a pumping motion as the turning member turns. The pump also includes at least one stabilization component in contact with the reciprocating member to stabilize the pumping motion.

Abstract: A high-pressure cam driven open discharge pump system is provided, wherein a high-pressure output at a relatively constant pressure is formed. The pump system includes a plurality of pressurizing subassemblies, each subassembly including a cam follower retained by a cam follower support guided by guide bearings to induce linear motion of a connected piston rod. The piston rod is slidably received within a removable high-pressure cylinder assembly which retains a high pressure cylinder.

Abstract: A pressure wave generator (40) for driving one or more cryogenic refrigerator systems. The pressure wave generator (40) comprises a housing with one or more inlet/outlet ports (57,58) through which generated pressure waves of gas may pass through to drive a cryogenic refrigerator system or systems connected to the inlet/outlet ports (57,58). The pressure waves are generated by at least on pair of opposed diaphragms (41,42) located in the housing that are moveable in a reciprocating motion within the housing to create pressure waves in gas spaces (55,56) associated with each diaphragm (41,42). The gas spaces (55,56) each having associated inlet/outlet ports (57,58) through which the pressure waves may pass. An operable drive system is also provided to move the pair of diaphragms (41,42) in a reciprocating motion.

Abstract: A reciprocating compressor is provided with a reciprocating compressor frame which includes a central body and at least two crosshead guides extending from opposite sides of the central body. Additionally, the compressor frame has angled crosshead guide support structures extending outwardly from the central body along a respective crosshead guide.

Abstract: A reciprocating air pump with a frame and a pump for compressing air through a series of linear close-strokes and open-strokes between a first portion and a reciprocating portion. The pump includes plural cylinders, slideably and sealably engaged therein, and arranged as multiple-chambers defining multiple-stages, for compression of air. A manifold with an air inlet cavity and inlet vent, and a compressed air outlet cavity with outlet vent. An outlet valve body is disposed between the first portion and the manifold, with an outlet valve that directs high-pressure compressed air into the outlet cavity, and with an inlet port coupled to the inlet cavity. A reciprocating linear drive with an electric motor delivers linear force to the reciprocating portion. A control system sequentially alternated the direction of force of the reciprocating linear drive, thereby applying linear force to the reciprocating portion.

Abstract: A reciprocating-piston compressor having at least two working cylinders arranged in series, along a cylinder axis is described. The compressor includes a piston in each of the cylinders, guided in an axially movable manner, and a common axially actuated piston rod of the pistons, extending through a passage opening in a partition between the at least two working cylinders. The at least two working cylinders are sealed off with respect to one another in a region of the common axially actuated piston rod, exclusively by a non-contact seal. The axial seal has an axial gap seal formed between a radially outer circumferential surface of the common axially actuated piston rod and a radially inner circumferential surface of the passage opening.

Abstract: An air pump has a one-piece cylinder and a piston assembly. The one-piece cylinder has a body, a cap, a pedal and a base formed together by injection molding and welding process. The piston assembly is mounted in the one-piece cylinder and has a rod, a handle and a piston. The one-piece cylinder is structurally firm and provides excellent hermetic characteristics.

Abstract: A radial piston pump having external loading. The radial piston pump has an inner eccentric which is attached to a rotatable driveshaft, a cylinder block which has positionally fixed cylinder bores aligned radially with respect to the driveshaft, and displacement pistons which are mounted in a longitudinally movable manner in the cylinder bores. The displacement pistons have a piston head with a short casing height, and are mounted with their piston base on the eccentric, in such a way that the piston head, during its longitudinal movement, pivots in a predetermined angle range (??) about the longitudinal central axis of the associated cylinder bore.

Abstract: A dual rocking piston pump which includes a first piston with a first connecting rod eccentrically mounted to a rotor shaft and a second piston with a second connecting rod eccentrically mounted to the rotor shaft. The rotor shaft passes through a first bearing and a second bearing before being connected to a rotor body. The rotor body is disposed within a stator. The first and second bearings and stator are supported by a bracket. The bracket includes a hub which, in turn includes a first end connected to a wall at an opening in the wall. The hub also includes a second end. The first end of the hub supports the first bearing at the wall and the second end of the hub supports the second bearing. Both the first and second bearings are disposed in front of the motor or in front of both the rotor and stator.

Abstract: A piston pump having a piston longitudinally movable in a housing. A first pressure chamber is delimited by the piston element and a component affixed to the housing. The first pressure chamber is connected to a suction region via an inlet valve and is operationally connected to a delivery side via an outlet valve. A compensation piston unit has a working piston chamber connected to the delivery side. A stroke volume of the first pressure chamber is twice the size of a stroke volume of the working piston chamber. The piston element and a component affixed to the housing delimit a second pressure chamber connected to the suction region which is operationally connected to the first pressure chamber during a suction stroke of the piston element whose volume varies by half the stroke volume of the first pressure chamber and expands with a delivery stroke of the piston element.

Abstract: A hand-held vacuum device includes a housing to hold an electrical motor operable to drive a piston pump that is configured to draw a substantially continuous vacuum for each complete cycle of the piston pump. The hand-held vacuum device also includes an expansion chamber releasably connected to and in fluid communication with the housing and a vacuum interface that has a vacuum connector in fluid communication with the expansion chamber and is configured to releasably couple to a valve disposed on a container. The expansion chamber separates air and liquid from a fluid drawn into the expansion chamber.

Abstract: A flexible impeller pump includes first and second component housings. The first component housing includes a first flexible impeller and the second component housing includes a second flexible impeller. As these impellers rotate within their respective housings, they draw in and expel individual components into a common receiving chamber. In a particular application, one component is a foamable liquid, and the other component is air, and a mixture of foamable liquid and air is thus created in the common receiving chamber.

Abstract: A mechanism for moving elements in a fluid filled housing a pump with the element to be moved attached rigidly to the pump or to a port assembly connected to the pump. The pump assembly or port assembly moves as a result of differential pressure created between a first and a second chamber separated from each other by the pump assembly or port assembly. Movement of the fluid in one direction increases or decreases pressure, the pressure change resulting in a net force in one direction or the other.

Abstract: A double-acting compressor to compress liquid or gaseous fluids includes a cylinder having a piston head that reciprocates between opposite ends of the cylinder; a fluid discharge and suction passages defined in at least one of the opposite ends of the cylinder; a fluid suction and compression chamber connected to each end of the cylinder; fluid suction and fluid discharge valves connected to each one of the opposite ends of the cylinder; and pulling device connected to each end of said piston head. The pulling device extends along the cylinder and project out of the ends of the cylinder. The pulling device includes at least one flexible string having fastening means for the manual operation of the compressor.

Abstract: A multiple-chamber, multiple-stage reciprocal pump for compressing air through a series of up-strokes and down-strokes. The pump includes an upper reciprocal portion and a fixed portion. The fixed portion further includes a base housing with an ambient air inlet cavity and a compressed air outlet cavity formed therein. It further includes an outlet valve body fixed to the base housing with an outlet valve pneumatically coupled to direct high-pressure compressed air into the outlet cavity. The outlet valve body also has an inlet port pneumatically coupled to the inlet cavity, and there are plural cylinders coupled to the outlet valve body, which slideably and sealably engaged with the upper reciprocal portion, thereby enabling the series of up-strokes and down-strokes to compress air.

Abstract: A fluid delivery system for delivering a metered dose of fluid from a supply tank (28) to a downstream chamber or vessel (10), comprises a pump apparatus (20) comprising a pump plunger (32) which is operable to perform a pumping stroke under the control of an electromagnetic actuator (36), including a solenoid (36a), to effect delivery of the fluid and a control unit (24) for supplying an input signal (58) to the solenoid (36a) to initiate a current flow to the solenoid (36a) and thereby initiate movement of the pump plunger (32). An electronic device (54) provides an output signal to indicate that movement of the pump plunger has stopped at the end of the pumping stroke, and a timer determines a time difference between the input signal (58) being supplied to the solenoid (36a) and the output signal being output by the electronic device (54).

Abstract: A high pressure radial piston fuel pump is featured having an hydraulic head with two or three individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where a rotating eccentric drive member with associated actuation ring are situated. A rolling interaction is provided between the actuation ring and the inner ends of the pistons for intermittent actuation. Relative rotation is provided between the actuation ring and the drive member. Respective inlet and outlet valve trains are situated in the head. The head is attachable to a removable mounting plate, and the drive member is rigidly carried by a drive shaft that is supported by two bushings, one located in the mounting plate and the other in the hydraulic head.

Abstract: Converting the dynamic energy of a fluid to generate electrical power may be accomplished by a variety of systems, processes, devices, and techniques. In particular, implementations, the movements of a gaseous fluid body may be used for generating electrical power by driving a pump using the motion of a flow-driven moveable member that rotates in response to movement of the fluid body. The driving of the pump may pressurize a pumping fluid with pistons located in multiple chambers of the pump, and the pressurized pumping fluid may be conveyed to an electrical power generator mechanism that generates electrical power using the pressurized pumping fluid.

Abstract: A high-pressure water pump for a pressure washer system includes an elliptical cam, a piston, and an unloader. The elliptical cam is designed to be powered by a prime mover, and is rotatable between a first orientation and a second orientation. The piston is designed to be driven within a chamber by the elliptical cam. During operation of the water pump, a flow of water enters the chamber through an inlet when the elliptical cam rotates to the first orientation. The flow of water exits the chamber at an increased pressure through an outlet when the elliptical cam rotates to the second orientation. The flow of water then exits the water pump through the unloader, which is designed to control pressure fluctuations in the flow of water, and is attached to the outlet of the chamber.

Abstract: Disclosed is a device for conveying liquid and/or gaseous media, comprising at least two pumping chambers whose volumes change periodically during operation. Each pumping chamber is provided with at least one intake and discharge valve while all pumping chambers are fitted with a common main inlet and a common main outlet. A drive unit which is configured such that the volumes of the pumping chambers change at a phase shift of 2?/number of chambers is allocated to the pumping chambers. Also disclosed is a device for conveying liquid and/or gaseous media, comprising at least two pumping chambers whose volumes change periodically during operation. Said pumping chambers are embodied and disposed such that at least two adjacent pumping chambers encompass a joint wall which is configured so as to modify the volume of the adjacent pumping chambers. The invention further relates to a method for conveying liquid and/or gaseous media with the aid of the disclosed device.

Abstract: This invention relates to a method of fabricating or machining the fluid end of a high pressure pump and a fluid end produced by the method. The method includes sculpturing the front side of the fluid end which results in a non-planar surface. In this manner the internal stresses can be varied at critical points within the fluid end.

Abstract: A reciprocating piston compressor for use in a refrigerant compression circuit comprises first and second intake manifolds, first and second reciprocating piston compression units, an outlet manifold and a first pulsing valve. The intake manifolds segregate inlet flow into the compressor. The first and second reciprocating piston compression units receive flow from the first and second intake manifolds, respectively. The outlet manifold collects and distributes compressed refrigerant from the compression units. The first pulsing valve is mounted externally of the first intake manifold to regulate refrigerant flow into the first intake manifold. In another embodiment, a second valve is mounted externally of the second intake manifold to regulate flow into the second intake manifold, and the first and second valves are operated by a controller. The controller activates the first valve with variable width pulses having intervals less than an operating inertia of the refrigerant compression circuit.

Abstract: A high pressure radial piston fuel pump is featured having an hydraulic head with two individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where a rotating eccentric drive member with associated actuation ring are situated. A rolling interaction is provided between the actuation ring and the inner ends of the pistons for intermittent actuation. Relative rotation is provided between the actuation ring and the drive member. Each piston has a piston bore that has a centerline that intersects the actuation ring but is offset (X) from the drive axis as viewed in cross section perpendicularly to the drive axis and the piston bore centerlines are parallel to each other but offset (Y) from each other as viewed in longitudinal section along the drive axis.

Abstract: A pump primarily for liquid paint includes first and second pistons reciprocable rectilinearly in respective first and second cylinders. The first and second pistons are moved relative to their respective pistons by operation of an A. C. electric motor the rotary output shaft of which is coupled to the first and second pistons by a constant velocity cam and a cam follower mechanism converting rotary motion of the output shaft into reciprocatory motion of the first and second pistons 180° out of phase with one another.

Abstract: A multiplex fluid pump assembled from a plurality of pump bodies connected side by side between opposing end plates with a plurality of fasteners tightened to compress the pump bodies between the end plates. Raised surfaces on opposite exterior side surfaces of each pump body are engaged with an adjacent end plate or an adjacent pump body to apply a pre-compressive force at the raised surfaces and thereby inhibit the initiation of fatigue cracks.

Abstract: A method for operating a reciprocating positive displacement pump for the simultaneous low-pulsation discharge of a plurality of liquids, having for each liquid at least two pump chambers and displacement devices capable of movement therein, of which the one displacement device takes in liquid during the actual discharge phase of the other displacement device, and at the end of its intake stroke reverses its direction of movement, and, in a pre-compression phase, pre-compresses the liquid taken into the associated pump chamber and when a predeterminable pre-compression pressure has been achieved comes to a standstill, and remains at the standstill until the other displacement device has ended its liquid discharge, and, subsequent to this discharge, begins its own discharge. The method includes the steps of carrying out a pressure compensation during the subsequent discharge stroke preventing a pressure compensation between the individual pump chambers during the subsequent discharge stroke.

Abstract: A dialysis machine valve manifold assembly includes a plurality of pneumatic valves; a plate including a first side and a second side, the plurality of pneumatic valves mounted to the first side of the plate, the second side of the plate defining a plurality of pneumatic flow paths; and a port header mounted removably to the plate, the port header including a plurality of ports configured to connect sealingly to pneumatic tubing, the ports in fluid communication with the pneumatic valves via the pneumatic flow paths defined in the plate.

Abstract: The new system is characterized by the fact that the displaced volume and the relative position of the intake, exhaust ports (31,30), sparkplugs, etc. in relation to the displacers (1,1? and 3,3), may be varied by modifying the angular and linear distance between the geometric axes of the double crankshaft (11), allowing this oscillating movement of varying speed, and the geometric axis of the arms (6,7) attached to the rotor with their respective displacers. By placing the double crankshaft (11) or the positive displacement machine on a chute (13) or sliding axes and change by means of a spindle (14) the distances between the geometrical axes, modify also the level of maximum and minimum distance among the displacer's. By modifying the angular distance between the fixed parts of the chamber and the double crankshaft the position of the intake and exhaust ports is also changed, this alteration can be operated with the system detained or in movement in a manual form or motorized and computerized form.

Abstract: A fluid pump assembly includes a double acting fluid cylinder with a housing, a piston reciprocally disposed within the housing, and a piston rod carrying the piston and extending from the housing. The piston rod has an end. A pump includes a pump body, a pressure loaded seal and a wiper seal. The pump body has a fluid inlet, a pump chamber and a rod port. The inlet is configured for receiving a fluid to be pumped and is in fluid communication with the pump chamber. The piston rod extends through the rod port and the end is positioned within the pump chamber. The pressure loaded seal is positioned within the rod port around the piston rod and has a pressure loaded end face toward the pump chamber. The wiper seal is positioned within the rod port around the piston rod on a side of the pressure loaded seal opposite from the pump chamber. The pump body further has a scavenging groove in an area between the pressure loaded seal and the wiper seal.

Abstract: The invention relates to a pump system for conveying a first fluid using a second fluid, said system comprising at least a first pump, said first pump comprising at least a first rigid outer casing defining a first interior space, a first flexible tube structure accommodated in the first interior space, wherein the interior of the first flexible tube structure is arranged for receiving one of said first or second fluids, wherein the region of the first interior space surrounding the first flexible tube structure is arranged for receiving said other of said first and second fluids, and wherein the first flexible tube structure is movable between laterally expanded and collapsed conditions for varying the volume of the interior of the first flexible tube structure, thereby imparting sequential discharge and intake strokes on said first fluid.

Abstract: A reciprocating compressor is provided. In one embodiment, a reciprocating compressor frame includes a central body and at least two crosshead guides extending from opposite sides of the central body. Additionally, the compressor frame crosshead guide support structures extending outwardly from the central body along a respective crosshead guide. Other embodiments of compression systems, devices, and frames of such systems are also provided.

Abstract: Piston systems comprise a housing including a first piston chamber and a second piston chamber therein. A first piston is movably disposed within the first piston chamber and a second piston is movably disposed within the second piston chamber. A flow path extends between and couples the first piston chamber and the second piston chamber. Reciprocating pumps comprising a flow path between a plurality of piston chambers and methods of driving reciprocating pumps are also disclosed.

Abstract: A pump includes a base and a cylinder installed on the base. The base defines a pumping channel. The cylinder defines a first chamber and a second chamber with a diameter different from that of the first chamber. The first and second chambers are in communication with the pumping channel. A first check valve only allows air to travel into the pumping channel from the first chamber. A second check valve allows air to travel into the pumping channel from the second chamber. A first piston is movable in the first chamber. A second piston is movable in the second chamber. A control device prevents the venting of air from the chambers in a first mode, vents air from the second chamber without traveling through the pumping channel in a second mode, and vents air from the first chamber without traveling through the pumping channel in a third mode.

Abstract: A feedback control loop for a high pressure pump modifies the accumulator velocity and pressure during solvent transfer. The accumulator velocity is adjusted to maintain the system pressure equal to the expected pressure to thereby eliminate the effect of the flow deficit created by a thermal effect.

Abstract: A multi-chambered pumping system is provided comprising an input cylinder configured to pump a source substance into a vessel and an effluent cylinder configured to receive an effluent from the vessel. The cylinders regulate the pressure of the source substance input into the vessel and recover the pressure of an effluent output from the vessel to pump additional quantities of source substance into the vessel. In each cylinder, a piston creates a boundary between two sections: a fluid section configured to receive working fluid and an effluent or input process section to receive the same. The fluid sections of the cylinders are in fluid communication. A guide rod is attached to each piston and may be operably sized to compensate for a pressure difference between a pressure at which the source substance is pumped into a vessel and the pressure at which an effluent is output from the vessel.

Abstract: A link mechanism provided between a lug plate and a cam plate in a variable displacement compressor includes a first transmitting portion for transmitting rotation of a lug plate to a cam plate and a second transmitting portion for transmitting compression reactive force from the cam plate to the lug plate, which are arranged along a rotational direction of the drive shaft. The first transmitting portion includes a first transmitting surface and a first receiving surface. The link mechanism also includes a movement restrictor arranged between the first and second transmitting portions. The movement restrictor includes a restricting surface formed in the lug plate and a restricted surface formed in the cam plate and restricts the first receiving surface to move away from the first transmitting surface in the rotational direction of the drive shaft in such a manner that the restricted surface comes into contact with the restricting surface.

Abstract: A modular system, the modular system including multiple inflatable modules, each of the multiple inflatable modules comprising: (a) an inflatable body that is adapted to be inflated from a contracted state to inflated state; and (b) multiple connectors, connected to the inflatable body, for connecting the inflatable module to at least one other inflatable module.

Abstract: A machine such as an external combustion engine in an electrical power and heat cogeneration unit comprises multiple cylinders, each driving an independent load or being independently driven, and a balance shaft comprising one or more off-centre balancing mass(es) to counteract rocking motion created by the piston motion and thereby assist in dynamically balancing the machine.

Abstract: A reciprocating compressor is provided. In one embodiment, the reciprocating compressor includes a frame having a central body and a crosshead guide extending from the central body. The compressor may also include a crosshead disposed within the crosshead guide and coupled to a crankshaft disposed within the central body of the frame. Additionally, the compressor may include at least one support structure extending from the crosshead guide to the central body, comprising an oblique support structure formed at an angle with respect to the horizontal and vertical dimensions of the crosshead. Other embodiments of compression systems, devices, and frames of such systems are also provided.

Abstract: A reciprocating pump assembly having a block body, a cylinder chamber in the block body, a plunger reciprocatingly disposed in the block body, an opening in the block body adjacent the cylinder chamber, and a cover plate in the opening. Threads on the outer periphery of the cover plate engage threads formed within the opening. The threaded outer periphery of the cover plate extends into the cylinder chamber and past the threaded portion of the opening so that the load on the cover plate transfers from fully formed threads on the cover plate to threads formed on the opening.

Abstract: The invention relates to a compressor (1) for gaseous and/or cryogenically liquefied media comprising a first compressor piston (6) and a second compressor piston (7), which are operatively connected to an eccentric shaft (2), wherein the second compressor piston (7) is arranged substantially opposite to the first compressor piston (6) relative to the eccentric shaft (2). To solve the object of providing such a compressor with a small space requirement and low construction costs, it is proposed according to the invention for the compressor (1) to be embodied as an oscillating piston-type compressor, wherein the first compressor piston (6) is arranged on an eccentric ring (4), which is effectively connected to the eccentric shaft (2) and wherein the second compressor piston (7) is fastened to a pivot lug (8), which is effectively connected to the eccentric ring (4).

Abstract: A pair of dual chamber mixing pumps are combined which allow for a constant dispense rate profile using motor speed modulation. Each pump is divided into two chambers, the proximal chamber and the distal chamber. The chambers are defined in part by a piston having proximal and distal ends and recessed sections. The pump utilizes one common driving mechanism to axially rotate and laterally reciprocate the piston to provide continuous pumping of fluids with reduced pulsations. Each fluid enters through its own pump inlet and outlet. The pumps are operated 90° out of phase with respect to each other.

Abstract: The present invention provides a double-piston mechanism of an emulsion squeeze head, having an actuating syringe and a suction pipe. A top of the suction pipe is connected to a pressing head, while an elastic resetter is arranged between the bottom of the suction pipe and the bottom wall of the actuating groove. The suction pipe is also provided with a piston set. The piston set includes a first piston, with a first connecting portion and a first flange, and a second piston. The first connecting portion is assembled onto the suction pipe, and the first flange is abutted on the wall of the actuating groove. The second piston, placed at one end of the first piston, includes a second connecting portion and a second flange. The second connecting portion is assembled onto the first piston, and the second flange is abutted on the wall of the actuating groove.

Abstract: Herein described is a frame (10) for a fluid machine of the reciprocating type. The frame (10) bears one or more cylinders (12) moving inside each of which, with a reciprocating movement, is a piston operated by a crankshaft (14). The frame (10) is made up of one or more modules (20) of the same size and shape, within each one of the modules (20) being provided a single chamber (16) adapted to accommodate the crank mechanisms of each single cylinder (12). Each module (20) is further provided with a pair of opposite side walls (22, 24) and with one or more fixing means (26) which allow rigid coupling to each other, adjacently arranging their respective side walls (22, 24), of two or more of the identical modules (20) for providing a frame (10) for fluid machines provided with two or more cylinders (12).

Abstract: A hydraulic pump assembly including a fluid reservoir, a body defining a fluid inlet and a fluid outlet, the fluid inlet being in fluid communication with the fluid reservoir, and a radially opposed piston pump assembly at least partially housed within the body and including a first piston pump mechanism and a second piston pump mechanism, the first piston pump mechanism being in fluid communication with the fluid inlet and having a first pump outlet, the second piston pump mechanism being in fluid communication with the fluid inlet and having a second pump outlet, wherein the first pump outlet and the second pump outlet are both in fluid communication with the fluid outlet.

Abstract: A dual piston-pump apparatus is provided having a pump chassis that includes a pair of spaced-apart, elongated piston bores, and a lead screw shaft. This shaft includes a motor driven end, and another portion thereof rotatably mounted to the chassis for rotation about a screw rotational axis. A piston drive member threadably cooperates with the lead screw shaft for selective reciprocating movement longitudinally along the screw rotational axis thereof between a first position and a second position. The drive member includes a pair of spaced-apart piston shafts, each piston shaft of which includes a respective piston head slideably received in a respective piston bore of the chassis. As the drive member is driven along the screw shaft between the first position and the second position, each piston head is simultaneously reciprocated between a dispensing condition and an aspiration condition.

Abstract: A pumping system comprising a pump (21) for conveying a pumped fluid using an actuating fluid. The pump comprising a rigid outer casing (25) defining an interior space (26), a tube structure (27) accommodated in the interior space (26), the tube structure (27) being flexible and substantially inelastic. The interior of the tube structure (27) defines a pumping chamber (28) for receiving pumped fluid. The tube structure (27) is movable between laterally expanded and collapsed conditions for varying the volume of the pumping chamber (28) thereby to provide discharge and intake strokes. The region of the interior space (26) surrounding the tube structure (27) defines an actuating region for receiving and accommodating actuating fluid. The pumping chamber (28) is adapted to receive pumped fluid to cause the tube structure (27) to move towards the expanded condition and the pumping chamber (28) thereby undergoing an intake stroke.