Abstract: An air compressor system having an actuator for controlling the energization of the primary and start windings of the compressor motor and the state of a relief valve is disclosed. No power is applied to either of the windings and said valve is closed when the actuator is disposed in the first position. Movement of the actuator to the second position energizes both of the windings and opens the relief valve so that the motor and compressor can reach full speed before a load is applied. When the actuator is released and moved to the third position, the start winding is deenergized and the relief valve is closed to allow an air storage tank to be filled.

Abstract: A stock liquor pressure pulsation absorbing apparatus of an active type is able to absorb pressure pulsations in an ordinarily demanded frequency range of 0.01 to 100 Hz. A by-pass pipe (2) extracts a portion of a stock liquor from a master pipe (1) for supplying the stock liquor to a paper machine headbox. A control pump (7) returns a portion of the stock liquor so extracted into the by-pass pipe. A detector (3) detects a stock liquor pulsation pressure at a branch point, or on an upstream side thereof, of the by-pass pipe and master pipe for controlling the control pump. The pressure pulsation, including the low frequency range, of the stock liquor is thereby absorbed accurately and precisely, variations in the basis weight are made small and a stable supply of final products with a high quality can be attained.

Abstract: First liquid pumping apparatus for containing a first quantity of first liquid, second liquid pumping apparatus for containing a second quantity of second liquid and control apparatus for alternately connecting the first liquid pumping apparatus and second liquid pumping apparatus to pressurized liquid utilization apparatus and for causing the first and second liquid pumping apparatus to alternately deliver the respective liquids to the liquid utilization apparatus at a substantially constant flow or substantially constant pressure; the first and second liquids may be the same liquid or different liquids.

Abstract: A water system uses a pressure reservoir of extremely small size. A valve device is placed between a water pump and the pressure reservoir. The valve device has a constant outlet pressure to limit the flow from the pump at high pressures. The pump is turned on and off by a pressure on/off switch. The valve device maintains the pressure to the reservoir at or below the on switch pressure except for a dribble flow. The dribble flow fills the reservoir when there is little or no water usage from the reservoir. The dribble flow is achieved by a notch in the valve surfaces of the valve device. Each time the valve opens any debris in the notch is washed from the notch thereby keeping the notch free of debris.

Abstract: A method for detecting the occurrence of surge in a centrifugal compressor includes the step of calculating a time rate of change of a discharge pressure of the fluid discharged from the compressor. In one preferred embodiment, the time rate of change of the discharge pressure is calculated by initially setting PREV PRESS and RATE PRESS variables equal to zero (0), and commencing a RATE PRESS subroutine having a time limit for cycling therethrough. The RATE PRESS subroutine includes the steps of obtaining a discharge pressure reading for the fluid discharged from the compressor, subtracting the discharge pressure reading from the PREV PRESS variable to establish the RATE PRESS variable, and resetting the PREV PRESS variable equal to the value of the discharge pressure reading. After the RATE PRESS variable has been determined, the RATE PRESS is compared with an acceptable set time point rate of change for the discharge pressure.

Abstract: The construction and operation of the control of this invention is designed to minimize pressure changes at pump changeover by sampling pump pressure characteristics for each pump cycle, calculating a compensating motion profile and applying the profile to the motor which drives the pump. This control can be used with any pump which has the following characteristics: positive displacement, repeating cycle characteristics, rotary motor drive and an output pressure cycle curve which never falls to zero.

Abstract: An in-tank fuel pump apparatus includes an elongated motor-pump unit having a motor and pump unit connected in end-to-end relation. An outer cam has a substantially constant diameter enclosing the motor-pump unit and projecting axially outwardly therefrom and defining a control chamber immediately adjacent the one end of the motor-pump unit. A control tower is secured to the end of the motor-pump unit from which the motor cam extends. The control tower includes a body member having a closure plate abutting the motor pump unit, an outlet passageway extending axially from the motor-pump unit to the exterior of the motor cam, a pressure sensor secured within the body member having an inlet connected to a sensing passage connected to the output of the motor pump unit in an outermost circuit board forming the outermost end of the tower unit.

Abstract: A system is provided for proceeding with automated filtration of liquids in a manner which allows for quantitative collection of desired filtrates or permeates. The system, as well as its associated method, monitors various parameters which are fed to a processor-controlled pump unit. This pump unit has several alternative modes of operation, including controlling the rate of flow through the pump unit. Data are received from one or more pressure sensors and preferably also from a scale. The processor-controlled pump unit operates on these data to control flow velocity and/or filter back pressure within the system.

Abstract: A constant pressure variable speed inverter control booster pump system including a control unit, an inverter controlled by the control unit to change output frequency subject to the pressure of the water supply pipe, a motor controlled by the inverter to drive a pump, a pressure transmitter installed to detect the pressure in the water supply pipe, and a pump controlled by the motor to pump water through the water supply pipe, wherein the control unit detects the change of pressure in the water supply pipe, and provides an analog signal DC 0V-10V to the inverter subject to the detection result, causing the inverter to change output frequency to the motor, so as to control the speed of the motor under a constant range.

Abstract: An apparatus for performing endoscopic surgical procedures within an internal body cavity. The apparatus includes an imaging unit for viewing the internal body cavity. In addition, the apparatus includes an intra-articular unit for providing a flow of fluid into the internal body cavity as well as for controllably withdrawing fluid from the internal body cavity. The apparatus further includes a cart which allows electrical intercommunication between the imaging unit and the intra-articular unit whereby the operation of the imaging unit and the intra-articular unit are interdependent.

Abstract: A fuel filter assembly of modular form is adapted to incorporate a lift pump or an automatic primer. The lift pump is mounted to the filter base by means of a lock ring. Fuel supplied to the filter base inlet is supplied to a rotary vane-type or gerotor pump which may be electrically activated from the vehicle console or a location remote from the fuel filter assembly. The lift pump regulates the fuel pressure to provide a sufficient fuel flow through the supply system and the filter for ultimate delivery to the fuel injection pump or engine. The pump/filter flow sequence is bi-directional and may be selected by the angular position of an adapter.

Abstract: An in-tank motor-pump unit includes a motor driven gear pump, a pressure transducer, and a control module as a single integrated package establishing fuel flow at a constant pressure by creating a pulse-modulated motor drive having a fixed "off" and a variable "on" period. A permanent magnet DC motor drives a rotary pump with the required torque operating over the specified speed range and without stalling out at low flow demand. An integrated circuit board includes an IC timing chip, operating in an astable mode, has an input connected to the transducer and an output connected to a MOSFET switch which connects the motor to a power supply. A series resistor connects an amplified voltage signal of the transducer to charge the capacitor and discharge resistor separately connects the capacitor to the input of the timing chip to generate a constant "off" period and a variable operative "on" period of the MOSFET.

Abstract: An auxiliary system for insuring adequate water supply during peak periods from a well with a low recovery rate. A gravity storage tank is replenished at a rate equal to or slightly lower than the recovery rate of the well. A float-controlled air shutoff valve prevents overfilling and allows water to drain from the storage tank to supply a pressure-responsive pump. The pump, together with a diaphragm pressure tank, supplies normal household use at varying flow rates, drawing its peak requirements from the gravity storage tank.

Abstract: A control system for an aircraft's electrically driven hydraulic pump. An electronic motor controller having closed loop feedback is utilized to directly control the prime mover speed in response to pump loading.

Abstract: Apparatus comprising a flow carrier connectable in a liquid flow system including an electric motor-pump unit and a conduit for conveying a pumped liquid to a liquid utilization apparatus. The flow carrier is connectable in the conduit and includes an opening which exposes the liquid flowing through the carrier. A heat sink or cold plate is located on the carrier over the opening, the heat sink covering the opening and having a wet side exposed to the liquid. The heat sink further includes a dry side, and heat generating electrical control components are secured to the dry side. A sensor is also mounted on the heat sink and responds to a characteristic, such as the pressure, of the liquid. A heat insulating layer extends around the control components and the sensor and covers the dry side of the heat sink, the layer preventing condensation. The sensor and the control components are operable to control the motor-pump unit.

Abstract: The high pressure system 10 is provided for outputting pressurized fluid to a source, such as a blasting gun 26. The system includes mechanical transmission 14 interconnecting a diesel engine 12 with a positive displacement pump 20. A programmable controller 30 is provided for receiving signals from a pressure transducer 34 and for controlling operation of an engine controller 44, a clutch controller 42, and a transmission shifter 46 to obtain the desired fluid pressure level output from the pump. The controller preferably communicates by wireless transmission technology, so that the controller 30 may be exterior of a sound abatement enclosure 28 surrounding the engine 12 and the transmission 14. Controller 30 may be operated to automatically shift the transmission in response to fluid pressure output from the pump. Alternatively, controller 30 may receive input instructions from the operator to shift the transmission to a desired gear.

Abstract: This invention provides a reciprocating pump system having means for determining the cylinder head pressure of at least one cylinder of each pump in the system. A control circuit continually determines the average cylinder head pressure, estimates the pump bearing life that has been consumed and the remaining pump bearing life from the pressure head information. The control circuit also controls the operation of the pumps as a function of cylinder head pressure. A temperature sensor coupled to the pump system provides temperature of the pump oil. The control circuit controls the operation of the pump as function of the pump oil temperature. The pump speed is decrease when the pump oil temperature exceeds a predetermined value. A vibration sensor coupled to the pump provides vibration level to the control circuit, which controls the pump operation in response thereto.

Abstract: An ambulatory volumetric pump apparatus includes a housing defining a channel therethrough having an inlet for receiving a fluid and an outlet for discharging a fluid, a pump operable to pump fluid through the channel, a motor for operating the pump in response to control signals, and a programmable microprocessor for selectively supplying control signals to the motor to cause the motor to operate. The programmable microprocessor is "programmed" by manually setting rotatable knobs having faces which extend through but are generally flush with the housing exterior surface. The knobs include indicia to provide a visual display of the setting of the knobs and thus of the parameters of operation of the pump. An under-pressure sensor is disposed after the inlet of the channel to detect a suction or vacuum in the channel and to signal the microprocessor if such condition is detected.

Abstract: A vacuum system and a method of operating a vacuum system. The system comprises a vacuum line, a pump, a pump motor, a pressure adjusting assembly, a pressure sensor and a control means. The pump is connected to the vacuum line for drawing fluids therefrom, and the motor is connected to the pump to drive the pump. The pressure adjusting assembly is connected to the vacuum line for conducting fluid into that line at an adjustable rate. The pressure sensor is connected to the vacuum line to generate a pressure signal representing the pressure in the vacuum line. The control means receives the pressure signal and generates a system control signal that is used to adjust the pressure in the vacuum line. The specific manner in which the pressure in the vacuum line is adjusted depends on the value of that pressure, and in particular, whether that pressure is in a first range or a second range.

Abstract: A method and an apparatus are provided for stopping a motor-driven pressure generating pump of a system for coating workpieces with atomized liquid coating material in case of an empty material reservoir or a leakage in a material supply from a material reservoir to the pump or from the pump to an atomizer. The pressure and/or the volume flow at the pump outlet and/or the speed of the pump piston or a value dependent thereon are continually measured. The measured values are then converted to electric signals to be input to an electronic analyzer and analyzed therein. If, during operation, the pressure and/or the volume flow drops below a predetermined value and/or the speed of the piston exceeds a predetermined value, the electrically controlled driving connection between motor and pump or the power supply to the pump motor will be cut-off by output signals from the electronic analyzer.

Abstract: An infusion apparatus includes a pump powered by a source of battery power and capable of operating in a plurality of infusion modes and operating in a power savings mode. The infusion apparatus further includes sensors which sense various conditions of the pump. A controller is programmed to periodically operate in a power-savings mode of operation and also selectively causes each sensor to be connected to the battery power only when the sensor is to detect a condition, thus further conserving battery power.

Abstract: A multiple electric motor hydraulic oil pump power system including a programmable controller having electric motor starting and stopping circuitry for hydraulic oil flow control. The circuitry having means to compare each electric motor running hours and select the motor with the least running hours to adjust oil flow to the desired amount. The system monitors oil pressure and flow, comparing such pressure and flow with the desired value and automatically adjusting the system to accomplish the correction. The controller also maintains safety sensing devices for high and low oil reservoir levels, oil filter condition limits, oil temperature limits, and means to maintain a constant oil pressure under load with load flow rates varying from very low to very high.

Abstract: The invention relates to a process and to a device for regulating a multiphase pumping assembly that includes notably at least one multiphase pump (1), a device (6) for determining a parameter representative of a working instability of multiphase pump (1) and at least one programmed processing assembly (7) allowing to store at least the determined parameter and initial parameter values, and to compute the new value of the speed of said multiphase pump in order to bring the working point of the pump back into its operating range.

Abstract: A control system 10 for monitoring operation of a high pressure plunger pump 12 includes a microprocessor-based controller 40 and a plurality of sensors. Inlet pressure transducers 48 output electrical signals to the controller at intervals of less than 1 millisecond, indicative of the instantaneous inlet pressure to the pump. The controller 40 shuts down pump operation if a number of instantaneous pressure signals within a selected time period exceeds a predetermined value, or if the average inlet pressure signal exceeds a preselected value. The control system 10 is substantially tamperproof, and stored data indicative of tampering, pump startup, pump shutdown, and pump alarm conditions are recorded in a memory for subsequent retrieval and analysis. The serial interface 82 allows communication between the system operating computer 68 and a setup/processing computer 84, which may optionally be remote from the control system by use of a modem.

Abstract: An ink jet printing system having an ink accumulator holding a supply of ink for delivery under pressure to printheads of the system, the volume of the supply decreasing as ink is delivered to the printheads, and a pump operable intermittently to pump ink from a supply to the accumulator when the volume in the accumulator decreases to a lower limit, operation of the pump being terminated when the volume in the accumulator increases to an upper limit.

Abstract: An automated control system for an engine-powered pump system. The pump system includes an engine with a battery and a pump. A control unit includes: a display, engine sensors, pump sensors, fluid level sensors, engine controllers, pump controllers, strobe light status display, and a battery recharge system.

Abstract: A calibration apparatus and method for calibrating a hydraulic control valve connected to an electronic controller. The electronic controller selects control signals and reads corresponding hydraulic pressure outputs of the hydraulic control valve and selectively records values corresponding to control signals that produce desired calibration pressures.

Abstract: A method and apparatus for evacuating a vacuum system which includes an evacuating portion comprising first and second vacuum pumps which are connected in series. The method and the apparatus are characterized in that the first vacuum pump is operated in a range from reverse rotation to forward rotation, and the second vacuum pump is rotated unidirectionally, thereby enabling pressure control of the vacuum system over a wide range.

Abstract: A method and apparatus are disclosed for controlling a multicompressor station so that the overall work requirement of the station is minimized while maintaining the compressors in a non-surge conditions. The apparatus includes interconnected control loops for controlling the turbine speed of variable speed compressors or the throttling valves of constant speed compressors that determine a set of criterion for computing the value and sign of the first derivative of work performed by the station. The speed of each compressor is then set to reduce overall system work while maintaining discharge pressure of the station and maintaining the compressors in a non-surge operating format. The method includes the steps of computing the criterion, computing the value and sign of the first derivative of the work function and adjusting the compressor speed to minimize station work while maintaining the compressors in a non-surge condition.

Abstract: A DC powered compressor system that uses a series of 12 volt batteries to provide multiple units of 12 volts power to a compressor motor as needed. A circuit arrangement comprises: a series of 12 volt batteries, a charging unit for the batteries when they are not powering the motor, and several switches to connect the batteries to the compressor motor when low pressure is detected. The arrangement allows the batteries to power the motor with a voltage equal to the sum of the batteries in series when low pressure in the compressor is detected and to allow a charging unit to charge the batteries when the motor is not being powered. A pressure switch in connection with the tank of the compressor activates the switches which disconnect the batteries from the charger and reconnects them to the motor upon detecting a drop in pressure in the tank.

Abstract: A scroll-type machine is disclosed which is particularly well suited for use as a compressor in refrigeration and air conditioning systems and incorporates a unique arrangement for modulating the capacity thereof. In one group of embodiments the capacity of the scroll-type machine is modulated by relative axial movement between the scroll members so as to form a leakage path across the wrap tips and opposed end plates. In another group of embodiments, modulation is achieved by reducing the orbital radius of one of the scroll members to thereby form a leakage path across the flank surfaces of the wraps. Both types of scroll separation may be accomplished in a time pulsed manner to thereby enable a full range of modulation with the duration of the loading and unloading periods being selected to maximize the efficiency of the overall system.

Abstract: The invention relates to a reaction chamber, which includes a cylindrical vessel, with at one end, at least one inlet or outlet tube or lead-through fitted with a valve for a liquid or gaseous component. The other end of the vessel is open. The reaction chamber further comprises a plunger, which performs a reciprocating movement within the cylindrical vessel in axial direction through the open end of the vessel. The plunger tightens against the inner wall of the cylindrical vessel, and has at least one channel, in substantially axial direction, fitted with a valve or connected to a tube fitted with a valve. The invention relates also to an assay method based on the use of the reaction chamber.

Abstract: A device for constant, automatic regulation of water pressure and flow in a water supply plant, comprising an electric pump fitted in the main water pipe, an adjustable pressure switch connected to the main water pipe, and an electronic control unit, which switches the pump on if the pressure falls short of a predetermined level or switches it off if a predetermined pressure level is exceeded. The device is characterized in that a turbine, incorporated in the water pipe, acts as a sensor, cooperating with a rotation signal transmitter which is connected to the electronic control unit in order to keep the pump switched on as long as the sensor detects a flow of water.

Abstract: A pool pump controller includes a pneumatic pressure sensor having at least one port disposed to react to negative pressure within a pool's pump intake chamber. The sensor input port, which includes a check valve, is connected to a pump control switch through a pneumatic tube. The pump control switch combines aspects of a diaphragm switch and an opto-interrupter to provide high-reliability control of the pump motor in a watery environment.

Abstract: A pressure regulated electric pump is characterized by a positive displacement double acting reciprocating pump driven by an electric motor through a planetary roller screw. A controller senses the pressure of liquid at an outlet from the pump and varies the speed of the motor in a manner to maintain the pressure substantially constant. At a constant flow demand from the pump the motor is operated at a substantially constant speed. As flow demand rises and falls the instantaneous pump outlet pressure falls and rises. The changing pressure is sensed by the controller which makes incremental changes in the speed of the motor to cause the motor to speed up during a pressure fall and to slow down during a pressure rise, in such manner as to maintain pump outlet pressure substantially constant.

Abstract: Paint spraying equipment having an electric motor, gear reducer and fluid section for pressurizing paint and a pressure control module utilizing a combined fluid manifold and pressure control component mounting frame formed of a single die casting and including an access port for servicing a pressure transducer and further including a paint relief aperture in the cover for directing leakage of paint to the exterior of the assembly.

Abstract: In a magnetically suspended type pump, an operating state of the pump can be obtained without using a pressure gauge and a flowmeter. In addition, in the case where the magnetically suspended type pump is applied to a blood pump, in order to reduce the number of connections in a flow path and to avoid thrombus formation, a correlation between current flowing in a motor and flow or a correlation between current flowing in the motor and pressure is obtained in advance, and the speed of rotation of motor is varied by a speed of rotation control circuit in response to an instruction from a CPU circuit, based on the obtained correlation between current and flow or between current and pressure, whereby flow or pressure is controlled.

Abstract: A centrifugal pump is of the type having a diffuser (1) with upstream and downstream ends (1a, 1b), a delivery body (3) fixed to the downstream end and including a delivery chamber, a suction body (2) fixed to an upstream ends (1a) of said diffuser (1) and including a suction chamber. A jacket (8) is fixed between the suction body and said delivery body, defining a space within. The pump includes a multi-functional chamber communicating with said jacket, a first auxiliary outlet communicating between said multi-functional chamber communicating and said suction chamber, a second auxiliary outlet communicating between said multi-functional chamber communicating and the external space, and outlet plugs for opening and closing the two outlets independently of one another. The pump is suitable for different pumping functions.

Abstract: A pump having a three-way valve has a motor for generating a turning effect by an electric power applied thereto. The pump pressurizes a fluid by using an impeller. The three-way valve is installed to the inlet side of the pump. A magnetic plate and ball swing between the first inlet and second inlet by means of load switches as many as a predetermined angle. The pump and three-way valve are integrally formed to require no separate piping between the three-way valve and pump. Thus, the manufacturing processing of the boiler is reduced while enhancing productivity. An installation space is shrunken to decrease the external dimensions of a product such as boilers.

Abstract: The present invention relates to a pumping method utilizing two suction inlet holes spaced a predetermined distance apart by an extension robe. In a variant, the pumping method utilizes two pump barrels cooperating each with the two inlet holes. In another variant, the pumping method utilizes a pump barrel and control for controlling the flow rates of effluents coming from the two inlet holes. Application of the method is preferable when pumping effluent from subhorizontal drain holes.

Abstract: A fluid pressure control system which is usable to control pressure in a fluid distribution system includes a variable speed drive coupled to a pump. A hydropneumatic tank is coupled to the distribution system. In normal operation, the variable speed drive actuates the pump so as to maintain pressure in the system. Under low flow conditions, a control unit, using the variable speed drive energizes the pump so as to pump fluid into and pressurize the hydropneumatic tank. The control unit then shuts off the pump. Pressure is maintained in the system, until a predetermined, lower, set point is reached as a result of pressure in the hydropneumatic tank.

Abstract: A safety device for avoiding entrapment at a water reservoir drain by using a vacuum operated switch to interrupt power to the reservoir pump whenever a blockage occurs. In addition, a manual reset switch requires human intervention to re-activate the reservoir pump once the blockage condition is removed.

Abstract: A check valve, for use in a vacuum accumulator. The check valve includes a movable gate, which blocks fluid flow. The gate carries a first electrical contact, which mates with a second electrical contact, when the gate closes, thereby issuing a signal which indicates closure. The invention eliminates the need for a separate pressure sensor, for sensing pressure within the accumulator.

Abstract: Disclosed is a mobile hydraulic system with a hydraulic pump, which is powered by a battery powered motor and fed from a hydraulic reservoir, whereby the pump, the battery, the motor and the hydraulic reservoir are a compact, portable hydraulic unit, to which a working tool, which is separated from the portable hydraulic unit and is exchangeable, can be connected via a hydraulic connecting line of the hydraulic pump.

Abstract: The device comprises: a branch (5) from the outlet (M) of the pump to a cavity (7) partially delimited by a membrane (14); a moving element (16, 22, 24) in a casing (9); a spring (36) pushing said element (16, 22, 24) toward the membrane (14) and capable of yielding under the action of a relatively restricted pressure of the water which reaches said cavity (7) and acts on the membrane; and moving electrical contacts (26) on said element (16, 22, 24), interacting with fixed contacts (28) of a supply circuit of the pump, to enable the pump to be switched on and to switch it off in the absence of pressure acting on the membrane (14).

Abstract: An apparatus and method for monitoring and controlling a motor driven sump pump. The apparatus and method includes a power supply which powers the apparatus, a sensing portion which detects the level of the liquid within the sump, a control portion which turns the motor either off or on in response to the level of the liquid, and an alarm portion cooperating with the sensor which activates an alarm when a preselected level has been reached. The apparatus and method also includes power failure detection portion cooperating with the alarm portion which activates an alarm when a power failure occurs, a fault detection portion cooperating with the alarm portion which activates an alarm when the fault condition occurs, and a disabling portion which disables the pump when the fault detection portion detects a fault condition in the pump.

Abstract: In a pump in which dual plunger is reciprocated with cams attached to the rotating shaft of a motor, the delivery pressure of liquid is measured during a certain period in each cycle of the pump. By setting the pressure during the certain period as a standard pressure value, the motor is controlled so that the delivery pressure during the remaining period in each cycle approaches to the standard pressure value. In this pump, rotating-speed-priority control and pressure-priority control are alternatingly performed to decrease pulsation during delivering liquid.

Abstract: An electric pump is turned ON and OFF by a main drive circuit including a negative pressure sensor for detecting a negative pressure in an accumulator, a first relay and a control device, and also turned ON and OFF by a back-up drive circuit including a negative pressure switch for detecting a negative pressure in an accumulator, and a second relay. For a period from the starting of the electric pump by the back-up drive circuit to the stopping of the electric pump by the main drive circuit, there is a period during which the electric pump is being driven only by the back-up drive circuit and a period during which the electric pump is being driven only by the main drive circuit. For each of these periods, a trouble of the main drive circuit and/or the back-up drive circuit can be determined by reference to a check signal indicative of the operational state of the electric pump. Thus, it is possible to reliably detect a trouble with the driving of the electric pump connected to the accumulator.

Abstract: A double-displacement pump is compact, has a modular fluid subassembly made up a substantially cylindrical pump body and a piston reciprocally driven within the pump body. An outlet fluid cavity is formed between the pump body and a surrounding housing structure, enabling the subassembly to be removed as a unit without the need to disconnect auxiliary systems, such as a pressure control system or a priming system. In a preferred embodiment, the subassembly is retained within the housing structure by an inlet fitting which includes a check valve. A second check valve is then provided in the piston itself, which has a stem threadingly engaged with a reciprocal drive element. A sleeve received over the stem serves to compress a fluid sealing structure against a flange of the piston when the stem is fully engaged with the drive element.

Abstract: In order to reduce the overall size of serial pump arrangements, several block-disk-like building elements are used. These building elements are made of a non-metallic material and lie against each other with their control surfaces in a sandwich like stack. Two of the block-disk-like building elements have displacement chambers oriented transversely to the axis of the stack, in each of which is guided a push piston. Inflow and outflow bores in which the high pressure mass flow, for example a chemical buffer, is created, extend parallel to the stack axis. Both building elements form two serially arranged pumping units of the serial pump arrangement and ensure a constant and continuous mass flow. Check valves are provided at the suction and delivery sides of both pumping units. Besides saving space, this arrangement ensures a highly constant and continuous mass flow, as the throughflow paths are as short as possible.