Abstract: A pressure transducer of the type employing a pressure-responsive diaphragm (11) with silicon piezoresistive strain gauges epitaxially deposited thereon is provided with integral digital thermal compensation of span shift and zero shift. The strain gauges are connected in a bridge circuit (30), and a differential voltage across the bridge circuit is amplified by an instrumentation amplifier (46). A temperature sensitive resistor (36) is deposited on the pressure-responsive diaphragm. This resistor is connected in a bridge circuit (35) the output of which is connected to an analog-to-digital (A/D) converter (54) which generates a digital number corresponding to the measured temperature of the piezoresistive strain gauges. This digital number is used to address pre-programmed correction data stored in a programmable read only memory (PROM) (53). The numerical correction data from the PROM is converted by a digital-to-analog (D/A) converter (55) to an analog correction signal.

Abstract: A drift compensating circuit cooperates with an air-pressure-to voltage transducer. The first input of a comparison circuit is connected to the transducer, while a reference voltage is connected to the second input. The reference voltage is provided by an up/down counter and a digital to analog converter. The comparison circuit has an output connected to the up/down counter to cause the counter to count up or down. The counter is enabled at predetermined intervals.

Abstract: A tubular metal sleeve having two annular welding end collars and a flexible intermediate sleeve portion between the collars is mounted in a bore of a housing. The sleeve permits passage of high temperature pressurized fluids impervious to the sleeve. The sleeve forms part of a gauge for detecting the pressure of the fluid. A spacer may be mounted in a space formed between the sleeve and the housing to reduce the quantity of pressure-transmitting liquid required to fill the space.

Abstract: A conditioning circuit for use with a pressure transducer is disclosed which provides a digitally readable electronic output signal indicative of capacitance sensed by the pressure transducer. The circuitry of the present invention utilizes an R-C charge/discharge circuit, thereby enabling the circuitry to be substantially more compact than previously utilized L-C circuits. The circuitry is usable with either pressure transducers having a single capacitance or those including a reference capacitance, and the circuitry provides a high resolution, high precision output.

Abstract: A pressure responsive apparatus having a Hall-effect detector is described. The apparatus preferably includes a pressure gauge having a Bourdon tube responsive to an external pressure. The Bourdon tube has mounted thereto a pair of magnets supported on, or attached to, an end thereof for generating a low power, magnetic flux field. The Hall-effect detector is mounted in proximity to the pair of magnets and generates an output voltage having values corresponding to movement of the magnets with respect to the detector. A processing circuit receives the output voltage from the Hall-effect detector, and in response thereto generates a plurality of output signals proportional to the sensed pressure variations in the Bourdon tube.

Abstract: A capacitive sensor is compensated for changes in the ratio of the capacitances of a pair of capacitors which result from changes in a relatively static background condition such as pressure. The compensation is achieved by providing a shunt capacitance for one of the sensor capacitors, the shunt capacitance being located such that it will not be effected by the background condition.

Abstract: A flange mounted pressure transmitter uses a filled assembly having pressure transmitting fill fluid in a sealed capillary extending between a barrier diaphragm exposed to a fluid being monitored and a pressure sensor located in a housing attached to one end of a protective extension tube containing the capillary and supporting the diaphragm at the other end thereof. A gasket ring and a transmitter mounting flange are located on the exterior surface of the protecting tube and are arranged to provide a means for attaching the extension tube to a housing containing the fluid being monitored. The gasket ring is arranged to be welded to the exterior surface of the extension tube at a selectable distance from the barrier diaphragm which is effective to produce a desired location of the extension tube and the diaphragm within the housing containing the fluid being monitored.

Abstract: An electronic control circuit for a bridge resistance circuit (10) of a transducer (20) has a switchable source of constant magnitude current (22) to direct current pulses of constant amplitude through the bridge circuit. A temperature setpoint detector (24) generates a temperature signal (TA) to a control logic circuit (26) when the circuit attains a predetermined temperature. The control logic circuit periodically turns on the current and directs a sample and hold network (32) to read the transducer output when the predetermined temperature is reached by enabling a gate (30). The control logic circuit turns off the current by applying a signal to the source of current after a reading of transducer output is taken. The current through the transducer develops its output, heats up the transducer and generates the temperature signal.

Abstract: A corrosion proof differential pressure transducer includes a central disk and two thin diaphragms mounted close to but spaced from the disk on both sides thereof, with the diaphragms being intercoupled to move together. This may be accomplished, for example, by a rod passing through a hole in the center of the central disk which is secured to each of the diaphragms; or by a fluid such as silicone oil in the space between the diaphragms and flowing through one or more holes through the central disk. At least one of the diaphragms, the central disk and the rod (when one is used) are formed of alumina, quartz, or other inert, insulating material having substantially zero mechanical hysteresis. One of the diaphragms may be a thin, tough, flexible insulating membrane. Conductive plates providing variable capacitance with changes in pressure may be mounted on the inner surface one or both of the diaphragms and on the facing surface of the central disk.

Abstract: An improved gas density transducer which compares the resonant frequency of an enclosed, reference tuning fork crystal oscillator with the resonant frequency of a detector tuning fork crystal oscillator exposed to the surrounding gas. The frequency of oscillation of the detector crystal oscillator exposed will vary in accordance with the gas density because of the motional resistance of the gas to vibrations of the tuning fork oscillator. The frequency of the detector oscillator can be compared to the frequency of the reference oscillator to determine the gas density.

Abstract: A method and apparatus are disclosed for deriving digital signals from analog variations of different sensing elements in a transducer. Each sensing device controls the frequency of a variable frequency oscillator, which is energized when a reading is to be taken for that specific sensing device. The periodic signal is coupled to a first counter which counts a presettable total number of cycles so as to establish a variable time period proportioned to the value represented by the then existing state of the sensing device. Concurrently, a second counter is operated for a like time interval, but counts cycles from a fixed frequency clock source at a much higher frequency. The number of cycles counted by the second counter is proportional to the analog signal from the sensing device. This arrangement enables the analog signals from the sensing devices to be digitized in sequence with compact circuitry having low power drain.

Abstract: A capacitive pressure sensor that is fabricated by a batch process affords isolation for the sensing element and leads from the pressure media and provides stress isolation as well. The pressure sensor is made up of a sandwich construction including a silicon wafer which is etched from one side to make cavities in a plurality of desired locations to form deflecting diaphragms, one surface of which acts as a capacitor plate. A glass layer is metalized on both sides and has holes drilled in locations that align with the diaphragms formed on the silicon wafer. The glass layer is anodically bonded to the wafer to form capacitance gap of a few microns relative to the one surface of each diaphragm. The assembly of the metalized glass layer and the silicon wafer is in a preferred form sandwiched between two additional layers, and bonded together in a vacuum atmosphere. The four layer sandwich is then cut up into individual sensors.

Abstract: A pressure transducer, which includes a silicon diaphragm with ion-implanted resistors in Wheatstone Bridge configuration and in insulating layer covering the diaphragm, is provided with temperature compensation for differences in thermal expansion coefficients of the layers by depositing a layer of aluminum onto the central portion of the diaphragm.

Abstract: A remote seal-type pressure signal generator has a pressure measuring end having a sealing diaphragm facing a pressure to be measured, a pressure detector body connected to the pressure measuring end through a first capillary tube, the detector body having a pressure-receiving space in which a pressure transmitting medium is liquid-sealed and pressure detecting means for detecting an internal pressure of the pressure-receiving space by way of a pressure difference thereof with respect to a pressure of a second pressure-receiving space to which a second pressure is applied, and a flexible protective pipe covering the capillary tube between said detector body and said pressure measuring end, a second capillary tube is housed in the protective tube, and extending from the second pressure-receiving space in the detector body while having substantially the same length as the first capillary tube, and having a distal end closed in the vicinity of the pressure measuring end, with the pressure transmitting medium bei

Abstract: A pressure transducer system which uses a Wheatstone bridge circuit to produce an electrical signal which is proportional to the amount of pressure exerted on it by gas or liquids, is disclosed. The Wheatstone bridge circuit is thermally isolated from the external environment using two diaphragms which are separated by a reservoir of silicone oil. This allows pressure to be hydraulically conveyed to the Wheatstone bridge circuit while preventing thermal contamination of the electrical signals produced by the Wheatstone bridge circuit. The pressure transducer also contains support circuitry which allows adjustment of the signals to and from the Wheatstone bridge circuit to enable the pressure transducer to be used with various electrical measuring equipment which has different operational ranges.

Abstract: A pressure measuring element includes a plate-shaped substrate of ceramic material and a membrane deformable in response to pressure fluctuations. The membrane is made of ceramic material and is mounted to the upper side of the substrate. A pressure-sensitive resistor for measuring pressure is positioned inside the membrane. A heating resistor element is positioned on the underside of the substrate, which maintains the temperature of the substrate constant. A temperature sensor is also arrayed on the upper side of the substrate near the membrane.

Abstract: A pressure sensor which comprises one or more measuring elements situated in a housing and a plate membrane sealing the housing against the medium to be measured and being attached to the measuring element on order to transmit the pressure to be measured, the plate membrane having curved or conically-shaped part which extends into the interior of the housing and compensates for temperature shock drifting.

Abstract: Extinguisher provided with a temperature compensated pressure controller, comprising a propelling agent and an extinguishing agent under gaseous form, wherein it comprises a sealed chamber filled with a mixture having a thermodynamic characteristic similar to that of the two agents in the extinguisher, a system for measuring the differential pressure exisiting between the inside of the sealed chamber and the chamber per se and a device actuated by the system for measuring the differential pressure and generating an alarm signal when the differential pressure exceeds a threshold value.

Abstract: A capacitance transducer construction for borehole pressure measurements where the support for one of the capacitor plates sets is mounted in an independent structure which is attached through a temperature compensating means to the support for the other capacitor plates for eliminating stress effects. Electron bonding of materials having graduated coefficients of friction is utilized to minimize stress effects.

Abstract: A quartz pressure transducer is disclosed which includes four or five elements, three of which are diaphragms containing deposited metal electrodes on both sides thereof. Since the electrodes are all on the diaphragms, the transducer disclosed herein is highly resistant to errors caused by changes in temperature, while retaining excellent resistance to errors caused by acceleration or vibration forces. The transducer may be constructed as either an absolute pressure sensor or as a differential pressure sensor, and in the primary embodiment contains a reference capacitance which may be used by appropriate electronic circuitry to provide compensation for acceleration or vibration forces, making the output of the pressure transducer of the present invention a highly accurate, highly sensitive indication of pressure sensed.

Abstract: An inflation pressure indicator (100) for pneumatic tires for vehicles has a body (101) mountable on a wheel rim (149) to which a tire is fitted. A piston (122) is slidably mounted in a bore (102) in the body (101), and, at a preselected pressure, moves in the bore (102) against the compression spring (125) to a position adjacent a datum line (136) on the body (101). A tire valve (130) is fitted to the piston (122) to enable the tire to be inflated or deflated, when an air hose fitting is connected to the body (101). By selective injection moulding of the body (101) from polycarbonate, the length of the body (101) will increase with increased heat so that the indicator (100) will correctly indicate the cold tire pressure when the tire is hot.

Abstract: A capacitive displacement type transducer, wherein the oscillation frequency of a self-excited oscillator circuit including a pair of differential capacitors formed with a movable electrode disposed between two outer electrodes is counted by a counter, the output level of the counter is reversed each time a certain count is attained to cause the differential capacitances to be switched alternatively, and to make identical the respective reversal periods, and application voltage to be applied to the differential capacitors being controlled by an integrator, and a voltage relating to the output of the integrator being applied through a fixed impedance to the movable electrode, thereby eliminating fixed capacitances formed across the difference capacitors. Also, a voltage generated by dividing and averaging the output level of the counter by use of a certain pulse duration of a monostable circuit operating in synchronism with a counter, is used to compensate for static pressure changes.

Abstract: A physiological pressure sensing and monitoring system including a sterile throwaway pressure transducing device. The device includes a pressure transducer mounted together with a flow control valve in a housing. The device includes a first connector for connecting the device to a source of sterile solution, a second connector for electrically connecting the pressure transducer to a monitoring device, and a third connector for selectively connecting the device to a catheter inserted into a patient's circulatory system. The device, including the connectors, is made to be low cost so as to permit the entire device to be installed and discarded as a unit so as to constitute a throwaway pressure sensing and flow regulator. The pressure transducer includes a novel mounting of the strain gage beam to the isolator which has been found to effectively avoid cracking and breaking of the beam from the stress forces applied thereto in the operation of the device.

Abstract: A temperature-compensated Bourdon tube gauge for indicating a parameter of a pressurized fluid, including a support structure, a Bourdon tube having an open fixed end receiving the fluid and a free closed end carrying an indicating member, a dial member carrying a parameter scale disposed along the path of motion of the indicating member, and a temperature-responsive element for moving the dial member in accordance with a sensed temperature such that the indicating member indicates the fluid parameter on the dial member scale. The temperature-responsive element comprises a bimetallic element connected between the support structure and the dial member. The bimetallic element may be connected to the dial member by a lever having a "variable fulcrum" which varies along the length of the lever in accordance with the shape of a cam with which the lever is maintained in contact.

Abstract: A corrosion proof differential pressure transducer includes a central disk and two thin ceramic diaphragms mounted close to but spaced from the disk on both sides thereof, with the diaphragms being intercoupled to move together. This may be accomplished, for example, by a rod passing through a hole in the center of the central disk which is secured to each of the diaphragms; or by a fluid such as silicone oil between the diaphragms and flowing through one or more holes through the central disk. The diaphragm, and disks and the rod are formed of alumina, quartz, or other inert, insulating material having substantially zero mechanical hysteresis. Conductive plates providing variable capacitance with changes in pressure are mounted on the inner surface one or both of the diaphragms and on the facing surface of the central disk. A housing and associated gaskets direct pressures from two different fluids to the two diaphragms, so that the differential pressure is measured.

Abstract: Physiologic pressure transducers convert an applied pressure (e.g., blood pressure) into an electric signal, which can be displayed by a monitor as a numerical value or continuous waveform. While reusable pressure transducers have been used for a number of years, innovations in solid-state technology have made disposable transducers feasible. In particular, disposal transducers which are impedance matched for use with monitors formally used for reusable transducers are disclosed. The pressure transducer is rugged due to the careful mounting of the transducer diaphragm and integral compensation circuitry. In addition, the geometric configuration of the flow path is uniform such that debubbling of the unit is easy.

Abstract: A pressure sensing device including a single crystal of silicon configured to have a diaphram portion, a frame portion and associated circuitry formed on the crystal is described. Piezo-resistive elements on the boundary of the frame and the diaphram portions of the crystal responds to changes in pressure. The piezo-resistive elements, associated elements, and connecting conducting paths are formed by thin film and/or doping techniques to provide a monolithically integrated circuit. The elements are passive and require only application of input voltages and detection of output signals to provide an operative component. Trimmable resistors are provided for compensation and resistive adjustment, and at least one resistive element provides temperature compensation.

Abstract: A device is provided for the very accurate measurement of fluid pressures, comprising a vertical cylinder (2), a piston (1) adapted for sliding in this cylinder with viscous friction, the pressure to be measured being applied to the upper face (23) of the piston in an upper enclosure (22), means for rotating said piston in said cylinder, a precision electromagnetic dynamometric display balance (B) comprising a piece (3) to which the force to be measured is applied and means for transmitting to the piece of the balance the force applied to the piston by the pressure to be measured, with limitation of the maximum forces, a lower sealed enclosure (22a, 44A-44d), this lower enclosure being able to be evacuated or pressurized to a desired pressure (the atmospheric pressure or that of a fluid), and means for permanently supplying the clearance between the piston (1) and the cylinder (2) with fluid.

Abstract: A circuit arrangement for compensating for the temperature dependence of the sensitivity and of the null point of a piezoresistive pressure sensor having a temperature sensor thermally coupled thereto. The temperature sensor is coupled to an auxiliary amplifier, in the output circuit of which the feed diagonal of the pressure sensor is connected. The output diagonal of the pressure sensor is connected to an output amplifier, to which a temperature-dependent correction voltage can be applied on the input side via a resistor arrangement. To perform the compensation of the temperature dependence of the sensitivity independently of the temperature dependence of the null point, the resistor arrangement is connected directly to the output of the temperature sensor, preferably via jumpers.

Abstract: Disclosed is a pressure transducer comprising a pressure sensitive silicon die having a front side exposing piezoresistive means and a back side for receiving pressure from a pressure medium. The transducer further comprises a pressure vessel having an aperture and apparatus including a hermetic seal for mounting the die with the front side of the die facing the aperture. In this manner, the die is compressed toward the pressure vessel when positive pressure is applied to the back side of the die by the pressure medium.

Abstract: A measuring diaphragm (1) separates in a pressure-tight manner two half chambers (9, 10) suitable for being respectively subjected to two pressures to be compared. In a central zone of the diaphragm (1) there are two magnetic cores (118, 127) which are disposed on opposite sides of the diaphragm in respective ones of the half chambers and which are displaced with the diaphragm when the faces of the diaphragm are subjected to different pressures. The cores are movable inside respective simple inductors (132, 133 ), thereby varying their impedances. By measuring this impedance variation it is possible to determine the position of the cores in the associated inductors, and consequently to establish the difference between the pressures being applied to respective faces of the measuring diaphragm (1). The above arrangement provides for automatic zero correction in an inductive differential pressure sensor.

Abstract: A diaphragm arranged between two pressure chambers is coupled through a diaphragm plate to a leaf spring. The leaf spring is fixed at one end and is provided with an actuating boss. A free end of the leaf spring serves as an armature which cooperates with a measurement transducer operating on the contactless principle. The measurement transducer delivers a constant electrical output signal as the input signal of a constant regulator or, alternatively, for switching a two-threshold regulator. Due to the low mass of such a leaf spring, the sensor incorporating the transducer is largely independent of orientation and insensitive to mechanical shock.

Abstract: A pressure-biased, temperature sensor means utilizing a cooperating pair of aligned bellows operators in a chamber communicating with a fluid system. One of the bellows expanding in response to an elevated temperature of said fluid and the second bellows expanding in response to a decrease in fluid pressure. Both of the bellows operate to move a diaphragm operator to close a switch means in a signal circuit thereby completing the circuit and energizing a signal means.

Abstract: Thermal shift in Wheatstone bridge-type transducers is reduced by providing a diaphragm of semiconductor material accepting formation of strain gages therein having a uniform temperature coefficient of resistance therethrough. That diaphragm is supported in a mechanically floating condition, such as by interposing a cushion of compliant material between the diaphragm and a support which is subject to mechanical strains. An amount of unbalance required for balancing the strain gages on the diaphragm is determined. One of these strain gages is provided with a series balance equal to one-half of that determined amount, while an adjacent one of the strain gages is provided with a shunt balance equivalent to one-half of that determined amount.

Abstract: A method and apparatus are described for converting variations in a measured variable (such as pressure) to corresponding variations in an electrical output signal. The preferred method utilizes a capacitive sensor whose capacitance changes to reflect changes in the measured variable. The changes in capacitance are preferably used to vary the gain of a switched-capacitor amplifier whose signal input receives a relatively constant DC reference voltage. The amplifiers' output may be sampled and further amplified to provide an output signal which is indicative of the value of the measured variable.

Abstract: A fire suppression bottle having a state-of-change indicator constructed to include two separate bellows arranged in opposed relationship. Each bellows is isolated from the other bellows, such that failure of either bellows has a fail-safe effect. The use of springs or other mechanisms that would affect the accuracy of the indicator is avoided.

Abstract: A capacitive type converter device, such as used for measuring pressure, comprising first and second rectifying circuits, each including an operational amplifier with a non-inverting input terminal connected to a reference point, to which a variable condenser is connected, the variable condenser having a capacitance which varies in response to a force being measured, such as pressure, and to which a reference condenser is connected, the reference condenser having a capacitance which is fixed independent of the force being measured.

Abstract: In a quartz barometer untilizing the temperature dependence of the resistance of a quartz oscillator at resonance, the present invention is directed to provide a circuit which compensates for the temperature change of the resistance at resonance by connecting a temperature-dependent resistor in series with a quartz oscillator thereby enabling said quartz barometer to measure gas pressure much more accurately.

Abstract: A checker for air conditioner with a pressure gauge, which comprises an auxiliary dial plate placed on the pressure gauge panel rotatable coaxially therewith. The auxiliary dial plate has an indicator zone and a temperature correction graduation arranged in such a manner, that the existing stand of charge of the coolant is indicated by the pressure gauge needle directly on the indicator zone, when the ambient temperature is set on the temperature correction graduation at a reference mark disposed on the gauge panel adjacent the temperature correction graduation.

Abstract: A pressure-temperature sensor for monitoring a fluid system for an over-temperature, an under-pressure or an over-pressure condition. The sensor includes a bellows operator enclosed in a fluid-filled housing with a normally-closed, first switch means and a normally-open second switch means. A diaphragm operator and a bellows are responsive to changes in temperature and pressure to, respectively, operate the first and second switches to indicate an over-temperature, an under-pressure or an over-pressure condition.

Abstract: A pressure-biased, temperature sensor for monitoring a fluid system for either an over-temperature or under-pressure condition. The sensor includes a bellows operator immersed in the fluid of a coolant system. The bellows operator expands in response to changes above a predetermined temperature or below a predetermined pressure to complete a signal circuit and energize a signal means.

Abstract: Disclosed is an externally loaded pressure sensor using a pair of SAW devices formed on the wall of an interior cavity. The difference frequency of these devices is used as a temperature-compensated measure of hydrostatic pressure on the sensor exterior. The termal response time of the sensor is shortened by matching to each other the sensor wall thicknesses adjacent the two SAW devices, e.g., by making these wall thicknesses approximately the same by means of forming an external flat on the sensor body.

Abstract: Disclosed is an externally loaded pressure sensor using a pair of SAW devices formed on the wall of an interior cavity. The difference frequency of these devices is used as a temperature-compensated measure of hydrostatic pressure on the sensor exterior. The cavity wall immediately adjacent the long sides of at least one of the SAW devices is rounded, to improve pressure sensitivity without unacceptable increase in stresses or other adverse effects.

Abstract: For measurement of gas pressure a gas-friction vacuum meter is used in whose measuring head a rotating body is suspended in a magnetic field contact-free between electromagnetic drive coils. The rotating body is set in motion with the aid of the drive coils and maintained at a rotational speed above a preset minimum rotational speed. The speed reduction of the rotating body occurring on account of gas friction is continually or intermittently balanced with current flows from a three-phase generator to the drive coils. In the measuring head rotational speed sensors are arranged and positioned, which detect and respond to the rotational frequency of the rotating body, and further transmit output signals to an electronic analyzer unit, which determines the pressure from the timely change of the rotation frequency.

Abstract: A pressure gage particularly suitable in a variable temperature environment includes a body carrying two force rods. One of the force rods is coupled to the source of pressure to be measured while the second, of similar length and parallel to the first, is separated from the pressure to be measured. The total strain on both rods is affected by the same factors except that the rod coupled to the source of pressure is also affected by that source of pressure. When the strain of the two rods are subtracted the resultant strain is attributed only to the measured pressure.

Abstract: A pressure fluid reservoir comprising a cylinder with a reservoir connection, a piston displaceable in the cylinder and non-contact switch means for indicating piston positions. Between the reservoir connection and the piston, the cylinder encloses a pressure fluid chamber, which is intended for storing a pressure fluid such as hydraulic oil, brake pressure fluid or the like. Opposite the pressure fluid chamber, the piston defines a gas chamber. The non-contact switch indicating means comprise Reed contacts, for example, and are disposed outside the cylinder such that they are longitudinally adjustable along the cylinder. Adjustment is effected by a temperature-dependent adjusting means, embodied for instance as an expansion element. Permanent-magnet actuating means, for actuating the Reed contacts in a non-contacting manner are fixed in recesses in one side of the piston.

Abstract: Methods and apparatus are provided for thermally compensating pressure determinations of pressure gauges through the use of a fast responding thermal device which is attached to the gauge and a dynamic model of the pressure gauge resonator which assumes that the temperature is not uniform throughout the resonator when temperature transients are present. The pressure gauge is subjected to known temperature and pressure conditions so that the parameters of a dynamic thermal model of the resonator may be determined, as well as a frequency and temperature to pressure mapping. The gauge may then be used to make measurements and provides a frequency output. The thermal device provides temperature readings. The temperature readings are input into a dynamic system using the dynamic thermal model to provide a correction to the frequency output of the pressure gauge such that the corrected frequency may be input into the frequency and temperature to pressure mapping to provide the thermally corrected pressure reading.

Abstract: A semiconductor-type pressure transducer is disclosed in which the pressure change is detected as a resistance change by use of a bridge circuit including at least a gauge resistor changing with an external force. Each gauge resistor is made of a PN junction of a semiconductor. The pressure transducer further comprises an amplification factor compensator for cancelling the effect of the temperature change of the gauge resistors making up the bridge circuit on the amplification factor of the amplification circuit for amplifying the output of the bridge circuit.

Abstract: A differential pressure transducer assembly for measuring flow in dirty and solids bearing fluids utilizes small barrier diaphragms located at the pressure taps of a flow measuring restriction. The barrier diaphragms are of minimum size and minimum thickness with a minimum volumetric compliance and are connected to a pressure receiving body by equal length capillaries of minimum i.d. A measuring transducer with a diaphragm having low volumetric displacement for measured differential pressures and having minimum volume diaphragm cavities is connected to the capillaries by equal and minimum volume cavities in the pressure receiving body.

Abstract: A differential pressure sensor senses a difference in pressure between a first input (low) pressure or "reference pressure" and a second input (high) pressure and provides a differential sensor signal representative of the difference in pressure. The reference pressure is sensed by a reference pressure sensor which provides a reference signal representative of the reference pressure. The differential sensor signal and the reference signal are provided to a correction circuit. The correction circuit, which is preferably a digital computer, adjusts the reference signal and provides an improved output signal as a function of the differential sensor signal and the adjusted reference signal.