Abstract: A control system for automatically controlling the operation of a hydraulic system for heavy construction equipment. The system of this invention provides a controller optimally connected to sensors and to control devices on the hydraulic system so that it automatically and optimally preheats the engine coolant and the hydraulic fluid of the heavy construction equipment before a normal starting operation in order to reach to an optimal operating temperature in a relatively short time. The control system automatically checks the operating temperature of the engine coolant and the hydraulic fluid by temperature sensors, and alarms the operator to any overheat condition by an alarm device. The control system also automatically controls the operational mode in order to remove the overheat condition thus preventing the temperature of the engine coolant and the hydraulic fluid from rising above a predetermined temperature.

Abstract: A fixed fluid capacity fluid coupling comprises a main bypass chamber and an auxiliary bypass chamber. The output wheel includes at least one hole and an offtake channel connecting the working circuit to the auxiliary bypass chamber uses this hole. Applications include fixed fluid capacity fluid couplings for driving high-inertia loads.

Abstract: A regenerator for a fluid power system is arranged to control flow rates while converting pressure drops accompanying resulting changes in flow rates into useful work. A gang of displacers are incorporated into a fluid flow network that also includes an array of selectable flow paths through the displacers. A control system, responsive to changes in demand for the flow of fluid, selects among the flow paths to operate the displacers in various combinations as motors, pumps, and recirculators for dividing the flow of fluid into two variably sized portions. One portion of the flow is sized to match the demand for fluid flow, and the other portion of the flow is converted into useful work.

Abstract: In a pressure-control device for affecting the closing behavior of powershift clutches (K.sub.1 -K.sub.X) in a powershift transmission, a regulating valve (1) cooperates with a damping device (2) as pressure-control valve. Chokes (4, 40, 400) for a more or less smooth connection are arranged in combination with pressure lines (P.sub.S, P.sub.R) over the pressure cycle when the clutch concerned (K.sub.1 -K.sub.X) is engaged. The travel of the damper piston (21) in a direction toward the regulating valve (1) is shortened by a pressurizing piston device (3) cooperating with the piston (21) of the damping device (2). Thus the time for the slipping phase in the engaged clutch concerned is shortened and, together with a higher initial pressure after the clutch is filled, the friction is limited.The limitation of the friction can also be obtained by adding a second choke in parallel in the control pressure line (Pr) by which the choked cross section is increased.

Abstract: A valve apparatus (30) of a hydraulic valve system has a plurality of directional control valves (78, 79) that control the flow of the hydraulic fluid to a plurality of actuators (34, 35). Check valves (59, 60) are provided for taking out, as a first control pressure, a maximum load pressure among load pressures of the plurality of actuators, first pressure generating devices (89, 91) for generating second control pressures different from the first control pressure, and second pressure generating devices (90, 92) for generating third control pressures different from said first and second control pressures.

Abstract: An airless hand held hydraulic pump unaffected by gravity continuously maintains pressure on the fluid in a dynamic reservoir chamber to enable pumping into a dynamic pressure chamber for actuating a forcing rod irrespective of the orientation of the pump. A release valve permits fluid return from the pressure chamber into the reservoir chamber. The pump can be fitted with a tool such as a door forcer.

Abstract: In a master cylinder, a communicating passage is formed in a piston guide which is disposed in a cylinder housing so that the communication passage is in communication with the through hole in said piston guide for supplying oil, and an annular spacer is interposed between the annular seal disposed at the side of the piston guide and the piston guide, an annular spacer which has a plurality of projections protruding outward from the external surface at intervals, so that the annular spacer is positioned in the cylinder housing with the projections of the annular spacer abutting the internal surface of the cylinder housing, and an oil passage is formed between the external surface of the annular spacer excluding the projections and the internal surface of the cylinder housing.

Abstract: An air fuel mixer is disclosed having a mixing duct, a shroud surrounding the upstream end of the mixing duct having contained therein a fuel manifold in flow communication with a fuel supply and control means, a set of inner and outer counter-rotating swirlers adjacent the upstream end of the mixing duct, hollow vanes in at least the outer swirler having passages therethrough in fluid communication with the fuel manifold to inject fuel into the mixing duct, and a hub separating the inner and outer swirlers to allow independent rotation thereof, wherein high pressure air from a compressor is injected into the mixing duct through the swirlers to form an intense shear region and fuel is injected into the mixing duct from the swirler vanes so that the high pressure air and the fuel is uniformly mixed therein so as to produce minimal formation of pollutants when the fuel/air mixture is exhausted out the downstream end of the mixing duct into the combustor and ignited.

Abstract: A heat machine comprising a displacer reciprocating within a housing. The displacer incorporates first and second independent, co-axial, overlapping regenerators. A first working volume is formed between the displacer and the housing at a hot end of the heat machine. Second and third working volumes are formed between the displacer and the housing at a cold end of the heat machine. A partition separates the second and third working volumes. A gas flow path exists from the first working volume to the third working volume via the first regenerator, the second working volume, a gas path within the partition, and the second regenerator.

Abstract: For air fractionation by two-stage rectification with subsequent production of crude argon, a component stream of the crude argon stream (25, 31) withdrawn from the crude argon column (2) is condensed (35) in indirect heat exchange (34) with a liquid oxygen product stream (40) from the medium pressure column (4), the oxygen product stream (40) being partially vaporized. The condensed crude argon (35) is then recycled into the crude argon column (20). A second component stream of the crude argon is obtained as the product (24).

Abstract: The present invention is an improvement to a process for the cryogenic distillation of air to produce both nitrogen and oxygen products carried out in a single distillation column system wherein a feed air stream is distilled thereby producing a nitrogen overhead and a liquid oxygen bottoms. The improvement is characterized in that: (a) operating the single distillation column at a pressure between 70 and 300 psia [480 and 2,070 kPa.sub.

Abstract: The present invention is a liquid nitrogen reflux means improvement capable of allowing the operation of conventional dual and triple reboiler air separation cycles at elevated pressures.

Abstract: A single pass ambient air heat exchanger for vaporizing and heating cryogenic liquids includes a plurality of vertically mounted and parallel connected heat exchange tubes. Each tube has plurality of external fins and a plurality of internal peripheral passageways symmetrically arranged about and in fluid communication with a central opening, preferably circular in cross section. A solid bar or rod extends within the central opening for a predetermined length of each tube to increase the rate of heat transfer between the cryogenic fluid in its vapor phase and the ambient air as compared to the rate of heat between the fluid in its vapor phase and the air in an unblocked tube so that the fluid is raised from its boiling temperature at the bottom of the tubes to a temperature at the top suitable for manufacturing and other operations.

Abstract: A vehicle air conditioning system has means for measuring a first physical quantity related to air conditioning system load to produce a first signal and means for measuring a second physical quantity related to air conditioning system cooling capacity to produce a second signal. Said first and second signals are used to calculate a predicted refrigerant charge for detection of, and protection from, an inadequate refrigerant charge.

Abstract: A thermistor is mounted between the fins of an evaporator. The thermistor senses the temperature about the evaporator when a blow fan mounted at the evaporator is driven and when it halts. The two sensed temperatures are compared, so that when the difference of the two temperatures is below a first set value, a defrost operation starts. When the temperature about the evaporator is above a second set value, the defrost operation is completed.

Abstract: A refrigeration appliance having at least two refrigeration compartments, each compartment having its own access door, is provided wherein there is a first evaporator for the first compartment the first evaporator operating at a first pressure level and a second evaporator for the second compartment, the second evaporator operating at a pressure level higher than the first pressure level. There is a control device for directing refrigerant to a selected one of the evaporators from a condenser and for preventing a flow of refrigerant into the first evaporator when refrigerant is being directed into the second evaporator to cool the second compartment. Around the first compartment is placed insulation having a higher thermal resistance than that placed around the second compartment since the first compartment is kept at a lower temperature that the second compartment. A phase change material may be used in association with one or both of the evaporators.

Abstract: In a multi-stage cold accumulation type refrigerator including a compressor disposed at an ordinary temperature, a helium gas as a common operating fluid to be compressed by the compressor, and one or more expansion chambers and cold accumulators of different temperature levels; a cold accumulating member of the cold accumulators is formed of an alloy or compound containing a rare earth metal, so that the efficiency of the refrigerator can be improved. Further, a heat generation quantity due to sliding resistance of a seal is set to be smaller than a theoretical generated refrigeration quantity to be obtained on the assumption of isothermal expansion in the expansion chambers, so that the refrigerating capacity can be improved. The refrigerator is applied to a cooling device for cooling a superconducting magnet, SQUID, superconducting computer, infrared telescope, etc.

Abstract: A system for providing intermittent cooling for personnel wearing protective garments and working in a hot contaminated environment is described which comprises a large flow capacity air control plenum operatively connected to an air conditioner of prescribed capacity and to suitable filters and blower for supplying about 20 cfm per person of air at a pressure of about 11 inches of water, wherein at least 80% of the system throughput is recirculated in providing the desired flow.

Abstract: An apparatus and method for conditioning air in deep, underground mines. The apparatus includes an air passageway connecting an air inlet for ambient air and an air outlet for conveying dried air to the mine's working level. The air passageway provides for dehumidification of the air by passing it through activated adsorbent particles, preferably zeolite, and for reactivating the particles by reverse heating cycles, or revolving the adsorbent beds through separate air flows, one for dehumidification of the air, and the other for regeneration of the adsorbent particles. The dehumidification unit contained within the air passageway is sufficiently efficient to reduce the moisture content of the air to less than 0.001 kilograms of water per kilogram of air. A humidifier at the mines's working level receives the dried air at an increased pressure and temperature due to the mine's depth, and by evaporative cooling reduces the air temperature so that it is cooled to 25.degree. C. dry bulb/20.degree. C.

Abstract: A reversible flow thermal expansion valve for use in a heat system is disclosed wherein the thermal expansion valve includes a valve body having a flowpath therethrough with an inlet and outlet, an expansion port within the flowpath, and an expansion valve to open and close the expansion port. An internal by-pass flow path by-passes the expansion port for reverse flow through the expansion valve. A check valve in the by-pass flow path prevents refrigerant from by-passing the expansion port during regular, forward flow through the expansion valve. The check valve has a spring to bias the check valve normally closed, and a bypass port communicating between a check valve guide path chamber and a check valve outlet in order to relieve pressure in the guide path chamber and increase the flow rate through the check valve.

Abstract: A beer keg cover constructed of wet or dry fabric and foam composite materials for scuba divers includes a top lid with an elastic edged opening to snap fit over the dispensing pipe of the keg, a circular zipper closure with a hinge attachment for the lid with a vertical slip opening closed by a zipper to open the cylindrical covering. The cover also includes openings aligned with the standard hand grips opening through the top vertical flange of the keg with sealing flaps to reduce heat transfer.

Abstract: The baffle for preventing the recirculation of discharged air into the intake grille of a packaged terminal air conditioner is provided with means for attaching it to the grille structure without fasteners. A plurality of flexible fingers with snap latches on the ends thereof are inserted between a pair of spaced ribs on the grille, with the fingers being flexed inwardly during the insertion process and then flexing outwardly to engage the snap latches with a front edge of the vertical ribs when the baffle is in place.

Abstract: A knit run cam for vertically moving a needle when fabrics are knitted. There is provided a knit run cam comprising two cams having a needle butt lowering bevel overlapped in a range of at least a part of the same phase in a moving direction of a carriage, one cam having a needle butt lowermost position higher than the other cam.

Abstract: The thread guide structure for double-cylinder circular knitting machines comprises a thread guide body which has an elongated configuration and has, proximate to one of its longitudinal ends, a thread dispensing passage. The thread guide body has a first part and a second part which are mutually articulated proximate to an intermediate region of the thread guide body. The first part, which is provided with the thread dispensing passage, is oscillatable with respect to the second part about an oscillation axis which is arranged transversely to the longitudinal extension of the thread guide body.

Abstract: An apparatus is provided for a bicycle lock assembly. A housing has an annular outer wall with a cable access slot and an integral rear wall. The rear wall supports a tubular inner wall that extends from the rear wall coaxially with the outer wall to define a torus shaped interior space. A reel provides a tubular core that is rotatably mounted onto the inner wall. The core supports a pair of spaced-apart guide walls which define a coiling space therebetween. A flexible cable is wound onto the reel between the guide walls. One end of the cable is fixed to the core. The other end of the cable extends through the access slot and includes a first lock mechanism. A coil spring has one end fixed to the annular outer wall and the other end fixed to the core of the reel. The spring lays in a spiral form adjacent to one of the guide walls such that rotation of the reel to unreel the cable causes the coil spring to tighten. Similarly, rotation of the reel to reel-in the cable causes the coil spring to loosen.

Abstract: An anti-theft device for coupling a seat back and a steering wheel of an automobile including a lock pivotally coupled to the seat back of the automobile and having a hook pivotally engaged on the lock for engagement on the steering wheel of the automobile, whereby, a person is prevented from quickly sitting on the driver seat of the automobile.

Abstract: A lock assembly for a gear shifter of a vehicle includes a base plate mounted to a floor of the vehicle adjacent to the gear shifter, a base frame mounted on the base plate, and a motor mounted on the base frame and having an output bevel gear. A pair of mount plates are spaced on the base frame. A hollow holder is movably mounted on two guiding bars which parallelly extend between the mount plates. A holder block is provided inside the hollow holder. A guiding sleeve mounted on the base plate receives a screw therein. An end of the screw extends out of the guiding sleeve and engages with a holder for securely holding the gear shifter and for moving therewith. A screw member is rotatably mounted in one of the mount plates. The screw member includes a bevel gear end which meshes with the bevel gear of the motor, a right hand thread portion which engages with the hollow holder, and a left hand thread portion which engages with the holder block.

Abstract: A lock for front-mounting through a panel opening in a panel, the lock having a face plate, a barrel extending transversely from the face plate, and a shaft extending from the barrel to receive a cam. The lock has a retaining spring with a base and two legs, the base and legs being formed of spring steel and being integral with one another, the base having a central opening receiving the shaft and being so dimensioned as to be able to pass through the panel opening when the base is mounted on the shaft, each of the legs having two sides of different lengths so that the outer ends of the legs are angular. The legs extend generally transversely of the base with the outer ends being spaced apart a greater distance than the size of the panel opening, so that when the lock is pressed through the panel opening the face plate will engage with one side of the panel and the outer ends will engage with the other side of the panel, securing the lock in position.

Abstract: The method and material of this invention eliminates the necessity of removing imbedded particles remaining after shot blasting by providing a method for surface finishing an orthopaedic implant wherein the blasting medium is bioactive. The surface finishing with bioactive material may also be used to clean the porous surface after sintering or diffusion bonding. Since the particles are made from bioactive material, it is not a concern if particles remain in the porous surface after blasting.

Abstract: A calibration system includes a transducer 36 positioned proximate to a physical disturbance monitoring system sensor 20. A test signal generator 34 causes the transducer 36 to produce an acoustic signal simulating a physical disturbance proximate to the sensor 20. The output of the sensor 20 responsive to the acoustics simulation signal may be compared to a predetermined reference signal to verify the calibration of the sensor 20.

Abstract: A housing for a fast exhaust gas sensor for cylinder-selective lambda measurements in an internal combustion engine comprises a hollow-cylindrical housing having at least two slot shaped openings that are arranged rotationally symmetrical over the circumference of the wall of the housing and extend parallel to the axis of the housing. Each of the slot shaped openings have edges that are overlapping in the fashion of a venetian blind so that the rotational symmetrical arrangement of the openings allows the housing and the exhaust gas sensor mounted within the housing to be integrated in an arbitrary rotational attitude relative to the exhaust gas stream in a pipe of a system.

Abstract: Disclosed herein is a test device for a stern drive motor of the type having a transom assembly including a bellows located between a inner transom portion and an outer transom portion, the device comprising: an inner sealing plug to seal against the inner transom portion; an outer sealing plug to seal against the outer transom portion, the inner and outer sealing plugs establishing a substantially air tight chamber within the inner and outer housing portions and the bellows. The device being further arranged to pressurize the bellows in order to detect leakage thereof.

Abstract: An apparatus for pressure testing a penetration seal between a process pipe and surrounding penetration sleeve of larger diameter, where the process pipe passes through the wall of a containment structure. A wrap-around elastomeric boot connects the penetration sleeve with the process pipe and defines a chamber communicating with the penetration seal to be tested. Inner and outer collar sets, each formed of an opposed pair of semi-cylindrical collar segments, are mounted over the process pipe and penetration sleeve and secured together in surrounding relation to the elastomeric boot. Wrap-around, pneumatically inflatable clamping rings are interposed between the respective collar sets and the ends of the elastomeric boot, to tightly and sealingly clamp the boot to the process pipe and penetration sleeve.

Abstract: Inner and outer welded steel protective tanks are separated by a space containing a granular insulating material such as perlite preventing excessive heating of fuel in a storage space in the inner tank, even when there is a fire at the site. The inner tank is subdivided into portions by a partition defining a storage space and an overfill containment space receiving overflow from the storage space portion, with a sensor detecting overflow. The overflow containment space is also arranged to collect separated fuel when the tank system is used with a vapor recovery system. The granular insulating material acts as an explosion suppressant by dissipating heat and fuel vapors which may be present in the insulation space as a result of leakage from the inner tank.

Abstract: Centrifuged material layer measurements are made in an evacuated glass or clear plastic tube which contains a float. When possibly contaminated materials, such as blood, are being tested the use of the evacuated tube allows the measurements to be made without the technician being exposed to the blood. The tubes are large enough to hold approximately one ml of blood, and are filled with an inert gas at low pressure. The floats are formed with a through passage into which the cell bands to be expanded will settle during centrifugation.

Abstract: A method and apparatus for determining the contents of salt and water in a water-in-oil type emulsified product are disclosed herein. In the method, two kinds of physical quantities which are related to the contents of water and salt in the water-in-oil type emulsified product and are capable of being measured in a short time are measured. Then, values of the contents of water and salt are calculated from the two physical quantities measured, by use of a bivariable multiple regression equation wherein the two physical quantities are used as explanatory variables and the contents of salt and water are used as objective variables.

Abstract: A novel method for determining a coefficient of moisture expansion of a single, identified workpiece or coupon. The method includes the steps of positioning the workpiece in a chamber having known environmental parameters; determining a workpiece length change .DELTA.L caused by a chamber induced change in the workpiece moisture content .DELTA.M, by positioning first and second transformers to opposite ends of the single workpiece; and, measuring a chamber induced change in the workpiece moisture content .DELTA.M, by weighing the workpiece.

Abstract: Disclosed is a self-diagnosis apparatus in a fuel evaporation gas scattering preventing system in an internal combustion engine.

Abstract: Devices and means to suspend scaled flying crafts during test and training flights, in a controlled environment space with a cable/string from a high point in the space, consisting of an electrical slack sensor on the cable/string and a radio controlled electrical system to automatically adjust the slack in the cable/string with the help of an electrically driven winch, permitting the flying craft to fly safely and freely under its own power.

Abstract: A tool which is capable of measuring parameters of a multi-phase flowstream without substantially restricting the flow in the wellbore is disclosed. The tool is comprised of a plurality of extendable arms which are radially spaced around and pivotably mounted in a housing so that each arm is extendable from the housing into the flowstream in the wellbore. Various types of sensors, e.g. flow sensors, capacitance sensors, temperature sensors, etc., can be used either alone or in combination which are carried at or near the outer ends of each of the arms whereby the sensors will be deployed from the housing into the flowstream by the arms without substantially restricting the flowstream through the wellbore.

Abstract: An improved drive shaft for a positive displacement type water meter includes a flexible spring arm formed on one end of the shaft for engaging the drive spindle of a nutating disk measuring element disposed within a water meter. The other end of the drive shaft is connected to a magnetic drive which, in turn, is magnetically coupled to a conventional mechanical register. Under normal conditions, the nutating disk measuring element and drive spindle oscillate in the water meter at a rate proportional to water meter flow. The drive spindle engages the spring arm of the drive shaft causing the drive shaft and magnet to rotate. The magnet is coupled through the water meter casing to a second magnet in the register. Rotation of the second magnet is used to drive the mechanical register to register water consumption. In the event the first magnet within the meter casing becomes frozen to the casing because of external freezing conditions, the drive spindle will snap past the flexible spring arm.

Abstract: An anemometer having a substrate onto which a temperature-dependent surface resistor is deposited. The active surface of the surface resistor is spaced from the leading edge of the substrate. A covering layer extends over the surface resistor and extends to the substrate at least in the area of the active surface.

Abstract: An acoustic fuel (or other liquid, powder or solid) sensor is disclosed. The sensor measures the volume of fuel in a container of known size. The air within the container is excited by an acoustic transducer. The transducer is driven by a frequency scanning source, and the frequency response of the air cavity within the container is monitored. This frequency response is then processed to determine the volume of air in the container, and the fuel volume is determined to be the total container volume less the air volume. In one embodiment, a tube connects the transducer through an orifice to the air volume, and the frequency response is observed to determine the resonant frequency of the air cavity within the container. The volume of the air cavity is then determined from the resonant frequency. The volume of the fuel is then determined from the tank volume minus the volume of the air cavity.

Abstract: A sensor element intended for a gyro, comprises an elongated body including at least one elongated element defining a tine and having a first and a second end. The first end is freely vibratable in two planes perpendicular to each other, designated as the X-Y plane and the Y-Z plane. The second end is fixedly secured in a body rotatable about a longitudinal axis which coincides with the planes. Drive and sensor electrodes are provided for piezoelectrically detecting vibrations of the first end, the drive electrodes providing vibrations in a plane perpendicular to the plane in which the sensor electrodes detect the vibrations, the drive and sensor electrodes covering substantial portions of the first vibratable end of the elongated element. The elongated element, at its second, fixedly secured end includes a transitional portion and an anchorage portion which do not participate in the vibration to any appreciable degree.

Abstract: A rotary accelerometer has capacitively coupled rotary and fixed thin film electrodes fixed to a substrate. The rotary electrode is angularly flexible and has a central hub secured to the substrate and spoke electrodes radially extending from the hub. Elongated electrodes are fixed to the substrate in circumferential positions on each side of each spoke electrode and in the same plane as the spoke electrodes. The rotary electrode, having a mass and being angularly flexible, responds to angular acceleration to differentially change the gaps between its spoke electrodes and the adjacent fixed electrodes. The fixed electrodes are energized with rectangular wave voltages of opposite phase. The sum of these voltages in the spoke electrodes is a function of the difference in the gaps which, in turn, is a function of the angular inertia of the rotary electrode.

Abstract: A semiconductor accelerometer comprising a semiconductor base member and an acceleration response member having a semiconductor beam integrally extending from the base member and a semiconductor weight integrally formed at a tip end of the beam so as to deflect the semiconductor beam when the weight is subjected to acceleration. At least one gauge diffusion resistor is formed in the semiconductor beam. The at least one gauge diffusion resistor includes a contact diffusion region which is formed at each end of the at least one gauge diffusion resistor and which has a diffusion concentration higher than that of the at least one gauge diffusion resistor. The contact diffusion region formed at each end of the at least one gauge diffusion resistor is connected to a wiring conductor.

Abstract: A method for measuring texture of metal plates or sheets using non-destructive ultrasonic investigation includes measuring the velocity of ultrasonic energy waves in lower order plate modes in one or more directions, and measuring phase velocity dispersion of higher order modes of the plate or sheet if needed. Texture or preferred grain orientation can be derived from these measurements with improves reliability and accuracy. The method can be utilized in production on moving metal plate or sheet.

Abstract: An apparatus for acoustically coupling an ultrasonic transducer with a body along whose surface waves are to be transmitted includes a wedge having a first surface for acoustically contacting a subject surface area of a body to be measured, on which surface waves are to be transmitted, and a second surface for accoustically contacting an ultrasonic transducer. The wedge includes a cylinder in which the second surface is present and which is movably disposed in a recess in a block in which the first surface is present, for orienting the first surface and the second surface relative to each other so that ultrasonic waves emitted by the ultrasonic transducer generate surface waves which travel on the subject surface area of the body when the ultrasonic transducer is in acoustic contact with the second surface and the first surface is in acoustic contact with the subject surface area of the body.

Abstract: An apparatus and a method for ascertaining the relative amount of two or more phases present in a multiphase flow, such as produced petroleum, through a pipe. Multiphase flow is temporarily diverted into a test section. Normal flow is then restored with fluids trapped in the test pipe. One or more floats of proper densities inside the test pipe are allowed to float to and stabilize at positions representative of the phase interfaces. An electromagnetic, radioactive, acoustic, or other sensor is used from outside the test pipe to locate the interfaces as indicated by the position of the floats. The relative amount of the various phases is then calculated. In an alternative embodiment, the velocity of a piston located inside the test section is also measured to give the total flow rate of the multiphase flow. The total volumetric flow rate, along with the relative phase amounts gives the absolute volumetric phase flow rates.

Abstract: A fluid flow measuring device having a positive displacement piston in a precise bore glass flowtube, with flexible diaphragms at opposite ends of the flowtube, to seal the flowtube from the ambient environment. The flowtube is filled with a pure fluid or gas for uncontaminated operation of the piston. Movement of the piston within the sealed flowtube is controlled by controlling the movement of each diaphragm. The diaphragms are supported in a housing connected to each opposite end of the flowtube, with a plenum chamber in communication with each diaphragm, and with means for the ingress and egress of the fluid under flow measurement with the plenum chamber.