Abstract: An improved diaphragm probe comprising a plate having a portion removed to form one or more cavities. At least two diaphragm strips sealed to close off each of the external openings of each of said one or more cavities. An incompressible fluid filling each cavity. A pressure sensitive instrument and means to transmit pressure changes at the diaphragms to said instrument in order to maximize the active diaphragm area with relation to the entry dimensions of the probe into a conduit.

Abstract: The disclosed pressure transducer assembly comprises a transducer for generating electrical signals in response to differential pressures; a structure for encasing the transducer, the encasing structure including first and second ports for communicating fluids at first and second pressures to the transducer; and a housing for enveloping the casing structure with fluid having a pressure at least approximately equal to the first or second pressure, the encasing structure being removably disposed within the housing.

Abstract: An isolator apparatus for coupling pressure from a pressurized fluid carried in a conduit to a pressure sensor in a pressure transmitter having an isolation diaphragm, isolation fluid, and a pressure sealing ring for providing an annular seal around an active region of the isolation diaphragm. The isolator apparatus includes a rigid support for spacing the pressure sealing ring away from the active region which reduces pressure measurement errors related to temperature-induced isolation fluid expansion, such that the annular seal overhangs the isolation diaphragm's active region.

Abstract: A differential pressure signal generator uses a pressure sensor arranged to sense differential pressure between a pair of right and left pressure measuring chambers in right and left portions of a signal generator body to which high and low pressure-side measured pressures are applied through respective barrier diaphragms and a center diaphragm arranged to define right and left pressure measuring chambers with the center diaphragm providing a pressure coupling to a fill fluid contacting the pressure sensor and being made of a material having a larger thermal expansion coefficient than the right and left portions of the generator body to provide an ambient temperature compensation by absorbing temperature induced volume changes in the full fluid. The temperature compensation is also applicable to an absolute pressure signal generator using a diaphragm to transmit a measured pressure to a sensor located within a body of the signal generator.

Abstract: Apparatus measures airflow when used with a hood to control the flow of air through the hood. The apparatus measures air velocity when used with a pitot tube, a probe, or a grid. Differential pressure is measured, and absolute pressure is also measured. A temperature probe and a humidity probe are used to obtain temperature and humidity measurements, and the measurements are used to correct airflow and air velocity measurements for the effects of temperature, humidity, and absolute pressure. Back pressure is compensated for when the hood apparatus is used for airflow measurements by utilizing a pair of movable flaps that are mechanically inserted into and removed from the airflow. A differential pressure circuit includes a voltage controlled oscillator which is linearized over a specific operating range, and the specific operating range depends on the differential pressure being measured.

Abstract: A pressure transmitter is coupled directly to an industry standard flange adapter union having a standard bolt hole spacing. Small diameter isolator diaphragms are positioned on the transmitter housing at locations so that the industry standard flange adapter union which couple fluid pressure sources to act on the isolator diaphragms without an intermediate large flange or manifold as is presently required and using the fasteners for the adapter union to complete the coupling. The smaller isolaters fit within the bolt hole spacing of the industry standard adapter union.

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 pneumatically operated pressure switch for monitoring the air pressure in a tire is provided with a second switch in its housing capsule. The second switch is connected to an oscillating circuit. This second switch changes the oscillating circuit upon sensing a change in the gas pressure in the reference pressure chamber. This leads to an error indication to the driver, and thereby provides a self-monitoring pressure switch for monitoring the air pressure in a tire.

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: Differential-pressure measuring apparatus comprising a casing providing a closed chamber filled with fluid and divided into two sections by a pressure-responsive element. The input pressures are applied to the two chamber sections respectively to develop a corresponding force on the pressure-responsive element. A sealed evacuated housing of non-magnetic material is in one chamber section and contains a double-tuning-fork (DTF) the resonant frequency of which varies with longitudinal tension force applied to the DTF. The force developed by the pressure-sensitive element is coupled by magnetic elements through the wall of the housing and to the DTF so as to control the resonant frequency of the DTF in accordance with the differential pressure to be measured. The DTF is activated to produce an output signal reflecting the differential pressure.

Abstract: A pressure transmitter assembly comprises a pressure transducer having a pair of inputs each connected to a separate pressure line. A valve is connected in each pressure line. A pressure equalizing line is connected between the pressure lines at a point between the valves and the pressure transducer. The pressure equalization line is provided with an equalization valve. All three valves are connected to a switching circuit which is controlled by a microprocessor. The switching circuit functions to open both of the valves in the pressure lines while closing the equalizing valves so that the pressure transducer is exposed to two separate pressure and generates a signal corresponding to a difference in two separate pressures. To zero the transducer and recalibrate the transmitter, the low pressure line valve is closed while the equalizing valve is opened. This equalizes the pressure between the two pressure lines so that any signal from the transducer corresponds to a zero pressure difference value.

Abstract: A one piece housing suitable for housing semiconductor chips is molded from a polymer material. Electrical leads pass through a molded one piece housing to provide electrical contact between the semiconductor die and external circuitry. A hole can be provided in the bottom of the package if the package is to be used as a unibody pressure transducer package.

Abstract: A digital differential pressure sensor with relatively low sensitivity to common mode line pressure errors. The sensor includes an airtight enclosure having a pair of pressure ports through which pressures are coupled to opposite sides of a pressure-sensing diaphragm, bellows, or Bourdon tube. The pressure-sensing elements generate torques which are transmitted by a shaft to stress-sensitive resonators which are isolated from the torque-producing elements by a sealed, flexible tube.

Abstract: Fluid density measuring apparatus and method for directly measuring fluid density or indirectly measuring force, acceleration, flow velocity, differential pressure and other parameters affecting the apparatus. The apparatus includes a bellows and a generally rigid hollow housing having openings through which fluid may flow to the interior of the housing, and a vibratory single-ended tuning fork mounted in the housing. The apparatus also includes circuitry for causing the tines of the tuning fork to resonate, for example, 180 degrees out of phase in a transverse direction, with the frequency of the tines varying with variation in the density of the fluid surrounding the tines. Circuitry is also included for determining the frequency at which the tuning fork tines resonate. When the density of the fluid into which the housing is placed changes, the frequency of vibration of the tines of the tuning fork is caused to change to provide a measure of the density change.

Abstract: A pressure difference measuring device having a semiconductor pressure sensor in a pressure pickup body which supports at each end face thereof a separating diaphragm with an adjacent supplemental diaphragm. On both sides of the semiconductor pressure sensor, a connecting canal is provided which leads in spur canals to the separating diaphragms and the supplemental diaphragms. In order to equip a pressure difference measuring device of this type with mechancial damping without adverse consequences for the operation of the overload protection, a damping element is arranged in at least one connecting canal. An equalizing diaphragm is associated with the semiconductor pressure sensor, the two sides of which are connected by the connecting canals in the region between the semiconductor pressure sensor and the damping element.

Abstract: A pressure gauge includes a cylindrical member having a flexible plate covering one end. Center flex of the plate is used to measure the force applied by fluid pressure. A low pressure transducer electrically measures the applied force. Pressure is transmitted from the flexible plate to the transducer by hydraulic fluid enclosed in the cylinder by a plastic boot. The boot is sealed to the cylinder by a sweat fit between the cylinder and a coaxial collar. The range of forces that can be measured is controlled by the thickness and diameter of the plate. In addition to pressure, the gauge can be used to measure temperature and orifice opening, and provide an indication of volumetric flow of the fluid.

Abstract: A differential pressure transmitter for process fluids is of the kind having a measuring transducer with a closed cell containing a filling liquid and a measuring diaphragm on both sides of which are arranged resistive, capacitive or inductive elements which are capable of converting a diaphragm deflection induced by differential pressure applied to the cell into electrical quantity changes. Inside the cell is provided at least one pressure sensitive component which is subjected to the pressure (s) of the filling liquid and is capable of providing an electrical output in accordance with the pressure values. This component is preferably a pasted carbon resistor, which permits output processed signal compensations in an electronic processing circuit to be made so as to minimize the effects of static pressure changes.

Abstract: Optical pressure transducers are used in devices for the measurement of the pressure of explosive gasses and liquids. In order to increase the sensitivity of the optical pressure transducer, the diaphragm (3) is made to be reflective on both sides. Two pairs of light conductors, each comprising a first light conductor (10, 11) for a light emission and a second light conductor (12, 13) for intercepting the light reflected by the diaphragm (3), are arranged on opposite sides of the diaphragm.

Abstract: A device for the pick-up of measured values having a frame forming a first measurement reference and an element movable relatively to the frame and forming a second measurement reference. The device includes a carrier connected to the element forming the second measurement reference and a mechanical/electrical conversion system connected between the frame and the carrier. The conversion system produces a magnetic field directed at right angles to the direction of movement of the carrier and has at least one air gap within which the carrier is arranged to move at right angles to the magnetic field. Two pairs of field plates are arranged in the air gap and when the carrier is moved the extent of penetration of the pairs of the field plates by the magnetic field is changed. The device also includes a bridge circuit by which the field plates are connected. The bridge circuit includes in one diagonal thereof a device for the display of measured values and is connected across the other diagonal thereof to a d.c.

Abstract: A transducer device for translating increments of linear displacement by means of opto-electronic sensing into increments of units expressed into units of volts. The device comprises an opto-electronic system, having a pair of co-planar, adjacently disposed radiation sensitive surfaces of square configuration, and a thereto facing, closely spaced surface of rectangular configuration being designed to emit a uniform pattern of radiation over its entire active surface. Wherein, the geometry of the emissive and sensing surfaces during relative movement provide a ratio of produced volt equivalent to the ratio of relative displacement between the emissive and sensing surfaces.

Abstract: A differential pressure gauge comprises a balance beam (3) acting upon a vibrating blade (6). The beam (3) and the blade (6) are disposed in a rigid chamber 4 under vacuum. The beam (3) is acted upon by a force, resulting from the deformation of a flexible or expansible chamber (7) subjected to a pressure P.sub.T and disposed in a second rigid chamber (5) subjected to a pressure P.sub.S. A flexible or expansible seal element (9) isolates the chambers but transmits the forces without disturbing them. This gauge has a high precision and delivers information in digital form, particularly useful in aeronautics.

Abstract: A mass air flow sensor (10) has a vortex generator (12) positioned in the air flow for generating two streams of vortices. Spaced vortex detectors (20), (22) are each positioned the same distance downstream of vortex generator (12) in one of the two streams of vortices. Vortex detectors (20), (22) are coupled to a differential amplifier (24) which reduces noise signals applied equally to vortex detectors (20), (22) and enhances vortex signals alternately applied to vortex detectors (20), (22).

Abstract: An improved construction is provided for fluid pressure responsive electrical switching apparatus, which achieves physical miniaturization, quick response time, sensitivity to relatively low levels of change or differential in fluid pressures, adaptability for employment in corrosive environments and under a very wide range of temperature conditions, simplicity and economy of fabrication and assembly, reliability of operation and general versatility for utilization in diverse applications. The improved apparatus involves, besides suitable housing structure that may provide for installation accommodating to various pressure and other conditions dictated by the application, a thin, wafer-like laminated switch assembly peripherally sealed in the housing structure and disposed for direct fluid communication with the fluid whose pressure is to be monitored for the purpose of controlling actuation of the switch assembly.

Abstract: The pressure-measuring device comprises a first chamber subjected to the pressure to be measured and a second chamber connected to the first through an opening fitted with a valve. The device further comprises a valve-control circuit and an element for detecting the instants at which the pressure difference between the two chambers attains a predetermined increment or decrement or a zero value. The detection element consists of a deformable pressure-tight wall placed between the two chambers and adapted to produce action on an optoelectronic, piezoelectric or electromechanical element which converts the deformation directly to logical signals. A bidirectional counter is provided for forward or backward counting of the increments and decrements obtained.

Abstract: A differential pressure sensing device is fully implanted beneath the skin in the living body such that its pressure responsive means, such as a diaphragm means, senses the difference in pressure between an internal bodily pressure and the pressure on the skin which is just above the sensor. The sensor has a stop, or a mechanical contact means, for the diaphragm means so that the diaphragm will be pressed against the stop when an externally applied pressure on the skin equals or exceeds the internal pressure. The sensor also has a means with a detectable parameter that can be detected outside the body by external apparatus. The external apparatus also converts the parameter to an audible sound or audio signal. The parameter has a specific response when the diaphragm is near the stop position, and this response can be heard via the audio signal.

Abstract: A process and device for plasma etching a thin layer. The process includes the steps of identifying a plateau in gas pressure that occurs slightly before the end of etching and then detecting a pressure variation (increase or decrease) from the plateau pressure. Etching is stopped at a predetermined time interval after the variation following the plateau begins. The device includes one or more pressure sensors and means for determining the plateau and subsequent pressure variation.

Abstract: The interior of a differential pressure cell is exposed to the pressure in the intake pipe of an internal combustion engine. An absolute pressure cell is exposed to the ambient air pressure. The movable membrane of the differential pressure cell carries a plate on which are mounted two permanent magnets whose North poles face one another. A Hall generator fastened to the center of the movable membrane of the absolute pressure cell moves in the gap between the two magnets. The effective magnetic field applied to the Hall generator thus varies with the relative position of the Hall generator and the magnets. Adjustment of the spring constants of the two membranes allows any linear combination of differential and absolute pressure to be formed. Embodiments of different complexity and different degrees of linearity are illustrated.

Abstract: An altitude difference measuring apparatus for measuring the difference between the altitudes at a first and second points on the basis of the barometric difference between the points, having an air pressure holding section with an electromagnetic valve for hermetrically containing an amount of air. At the first place an amount of the ambient air is held hermetrically in the air pressure holding section, and at the second place the barometric difference between the air pressure in the air pressure holding section and the ambient air pressure is converted into an electric signal, and in accordance with the electric signal the difference between the altitudes at the first and second points is indicated.

Abstract: The pressure difference across a pneumotach restriction is sampled with a gas chopper connected across a pressure difference detecting transducer. The gas chopper alternates the pressures backward and forward in application to the transducer so that the latter develops an AC sampling signal, the strength of which is related to flow. This AC signal is sampled in synchronism over intervals having a duration related to the power line frequency to develop an integrated value of the pressure difference free of drift caused by power line interference. The resultant signal is smoothed and summed in alternating response at double the gas chopper sampling rate to give a smooth output which is then multiplied by a linearizing circuit to obtain a flow signal which is proportional to the pressure difference. Specific gas flow structures and electronic sampling circuitry are disclosed.

Abstract: A hybrid sensor for simultaneously sensing pressure and temperature in non-interacting manner, includes an insulative substrate having a temperature-sensitive printed thick film resistor fabricated thereon. A conductive plate is insulatively spaced above the resistor and supported by a pressure-tight insulative barrier. The distributed capacitance between the plate and the resistive pattern is a function of the pressure applied to the exterior face of the plate, while the resistance of the resistive thick film is a function of temperature of the surrounding environment.

Abstract: A distance measuring apparatus and a differential pressure transmitter utilizing the same having an ultrasonic element reflector mounted between a pair of ultrasonic transducers. The alternate operation of the ultrasonic transducers produces a pair of transducer energizing signals which are related to the relative separation of the reflector element from the transducers. In one embodiment, the reflector element is mounted within a closed pressure vessel divided internally by an ultrasonic reflector diaphragm with a pair of fluid inlet lines admitting respective pressurized fluids to corresponding sides of the reflector diaphragm.

Abstract: A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates with the internal pressure of the body to be measured on one side and the atmospheric pressure on the other, the latter communicated through the intact skin and a nearly coplanar membrane. The movable element's differential pressure dependent displacement changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit, and the change is detected external to the body by a radiating detector system, such as a frequency swept radio frequency oscillator, by which the internal pressure is read out.

Abstract: A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates on one side with the internal pressure to be measured and on the other side with an external pressure which is applied by an external pressurizer-control system and which is communicated to the sensor through the intact skin. An imbalance of the two opposing pressures causes a displacement of the movable element which changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit. This change is detected outside the body by an external detection system, such as a frequency swept radio frequency oscillator. The external pressure is varied until the external detector senses that the pressures are balanced on the movable element, at which point the external pressure equals the internal pressure, and the former is measured and read out.

Abstract: An indicating device for a vacuum cleaner having means which operates as a result of the pressure difference between the inside of a filter dust container and the outside thereof and is provided with means for communicating the degree of clogging of the dust container through a signalling device in the form of a light source or light sources that gives a visual indication of the amount of clogging of the paper dust container.

Abstract: A differential-pressure measuring instrument comprising a main body assembly with a pair of diaphragms each subject to a respective fluid pressure. The diaphragms enclose a sealed chamber containing a fill-liquid surrounding a non-magnetic vibratable wire which is tensioned in accordance with the applied differential pressure. A magnetic field passes transversely through the wire, and electrical current is supplied to the wire by electronic circuit means to produce a vibratory force on the wire as a result of interaction between the electrical current and the magnetic field.

Abstract: A differential-pressure measuring instrument comprising a main body assembly with a pair of diaphragms each subject to a respective fluid pressure. The diaphragms enclose a sealed chamber containing a fill-liquid surrounding a non-magnetic vibratable wire which is tensioned in accordance with the applied differential pressure. A magnetic field passes transversely through the wire, and electrical current is supplied to the wire by electronic circuit means to produce a vibratory force on the wire as a result of interaction between the electrical current and the magnetic field.

Abstract: An optical pressure transducer utilizing a deformable diaphragm having a reflective surface in which a fiber optic bundle having at least 100 optical fibers is randomly divided at one end into two bundles consisting of a light source bundle, the end of which is irradiated by a light source, and a reflected light bundle, the end of which conveys light reflected from a pressure-sensitive diaphragm to a light detection means.

Abstract: A method and apparatus for protecting the transducer in a liquid-filled differential pressure transmitter having stroke limited, isolation diaphragms from exposure to overrange pressure are disclosed. Bidirectional overrange pressure protection is provided through the use of a single, preloaded bellows that is restrained by a preloaded stop means preferably including a preloaded mechanical spring. The bellows remains stationary when the differential pressure transmitter is exposed to a normal, operational differential pressure. When an overrange pressure is applied to the transmitter, the bellows expands or contracts to accommodate the liquid displaced by either of the isolation diaphragms thereby protecting the transducer from the overrange pressure. Upon removal of the overrange pressure condition, the protection apparatus automatically resets itself.

Abstract: Apparatus for measuring a pressure differential in a fluid carrying conduit characterized by a digital representation of the rate of fluid flow and a high degree of accuracy is disclosed. The sensor portion of the apparatus includes two identical electrically driven piezoelectric crystals. One crystal provides a series of pulses at its resonant frequency for use as a reference signal. The second crystal provides a series of pulses at a frequency which is inversely related to a force applied thereto. The sensor further includes two (minimally) arcuately curved stainless steel sealing diaphragms urged in opposing directions by two pressures acting in opposing directions. The movement of the two diaphragms, which are rigidly connected to one another, and which is directly related to the difference in magnitude of the two pressures, is used to apply the force to the second crystal.

Abstract: Apparatus for displaying pressure in digital form including a plurality of pressure-sensitive transducers arranged in a vertical linear array within a liquid container, from a most sensitive position to a least sensitive position. Electronic matrix means responsive to actuation of the transducers provide an output signal indicative of the least sensitively positioned transducer that has been actuated. A digital display device is coupled to the output of the electronic matrix means and is responsive to the output signal, for displaying in digital form the pressure in the container.

Abstract: A fluid pressure transducer comprises a chamber; one or more matched, plate-like crystals within the chamber; electrical means for exciting each of the crystals and means for transmitting forces originating from fluid pressures on two diaphragms located on the chamber to the crystal or crystals so as to produce a change in the resonant frequency of the crystal or crystals. This change is a measure of the difference in fluid pressures applied to the two diaphragms. SPThis application is a continuation-in-part of my copending application Ser. No. 499,489 filed Oct. 22, 1974, now U.S. Pat. No. 4,020,448 issued Apr. 26, 1977. The specification and drawings of that prior application are hereby incorporated into this application by reference.

Abstract: A method and apparatus for analyzing a damped structural specimen permits undamped mobility values and modal accelerations to be determined. The specimen is excited by vibrations in conventional fashion, and both actual and modified mobility response curves or characteristics are determined from measured responses. The modified mobility curve is produced by adding to a signal representing the vibratory force applied to the specimen an artificial force signal generated electronically. The generated artificial force signal simulates the addition or subtraction of mass at the point on the specimen where responses are measured. An undamped mobility value of the damped specimen is determinable at resonant frequencies indicated by the modified mobility curve. From the undamped mobility value and the corresponding frequencies, it is possible to determine modal accelerations for the various vibratory modes of the specimen.