Abstract: A thermal conductivity gauge measures gas pressure within a chamber. A sensor wire and a resistor form a circuit coupled between a power input and ground, where the sensor wire extends into the chamber and connects to the resistor via a terminal. A controller adjusts the power input, as a function of a voltage at the terminal and a voltage at the power input, to bring the sensor wire to a target temperature. Based on the adjusted power input, the controller can determine a measure of the gas pressure within the chamber.

Abstract: A device for measuring pressure having at least one pressure sensor with at least one active sensor surface, an oscillating and/or variable temperature counter-surface arranged opposite the at least one sensor surface, wherein the sensor surface and the counter-surface are arranged in a hollow body, and the hollow body has at least one opening, and wherein at least one alternating signal amplifier is provided.

Abstract: An improved Pirani sensor uses a measuring element disposed within a fluid between a base plate and a cover. The measuring element is held by suspension members that are connected to the base plate. A heating element is thermally conductively connected to the suspension members. Using the sensor the characteristic of the fluid is determined by evaluating the heat transfer from the thermal element through the fluid into the cover when heating power is applied to measuring element. Parasitic conductive heat loss from the measuring element into the suspension members is compensated by applying power to the heating element.

Abstract: A slat disconnect sensor includes a base. First and second arms are spaced apart from one another and are operatively supported by the base. At least one of the first and second arms have an end mounted to the base and is rotatable relative thereto at a pivot between connect and disconnect conditions. A mechanical link includes first and second link portions respectively secured to the first and second arms. The link interconnects the first and second arms and includes a weakened area providing a frangible connection in the connect condition and is configured to break at the frangible connection in the disconnect condition. A fuse includes first and second fuse portions operatively mounted to the first and second arms. The fuse is interconnected between the first and second arms providing continuity in the connected condition, and continuity is broken between the first and second portions in the disconnect condition.

Abstract: An apparatus and method precisely measure gas pressure over a large dynamic range and with good immunity to temperature fluctuations, encompassing applications such as gas sensing, bolometer imaging and industrial process monitoring. The micro-thermistor gas pressure sensor assembly includes a suspended platform micro-thermistor sensor device exposed to the gas pressure of a given atmospheric environment, an electrical readout circuit connected to the suspended platform micro-thermistor sensor device, wherein the suspended platform micro-thermistor sensor device acts as a variable electrical resistance in the readout electrical circuit, a binary-wave voltage source connected to the suspended platform micro-thermistor sensor device, and an ohmmeter.

Abstract: An ionization vacuum gauge includes a cathode, an anode and an ion collector. The anode is surrounding the cathode. The ion collector is surrounding the anode. The cathode, the anode and the ion collector are concentrically aligned and arranged in that order. The anode comprises a carbon nanotube structure including a plurality of carbon nanotubes.

Abstract: A method for sensing gas composition and gas pressure, based on the thermal constants of a variable electrical resistor, is presented. The method for sensing gas composition and pressure includes monitoring a variable electrical resistor whose dynamic thermal response is determined by the thermal conductivity and thermal capacity of the surrounding gas of a given atmospheric environment. In the thermal domain, the sensor has a low-pass characteristic, whose phase delay is determined by the thermodynamic characteristics of the surrounding gas such as composition and pressure. The method can be used for sensing gas composition and can also be used for sensing gas pressure.

Abstract: A Pirani vacuum gauge in which a response to a rapid pressure rise is improved and restrictions on a mounting direction of a container on a chamber to be measured for pressure are eliminated is provided. The Pirani vacuum gauge includes a heat filament of metal wire and a support unit for supporting the heat filament in a container, wherein a gas pressure is measured based on an amount of heat conducted away from the heat filament by gas molecules colliding with the heat filament, characterized in that a body of the container is filled with metal material, but a first cylindrical bore and a second cylindrical bore extend through the body, the heat filament being inserted into the first cylindrical bore and the support unit being inserted into the second cylindrical bore.

Abstract: An apparatus and method precisely measure gas pressure over a large dynamic range and with good immunity to temperature fluctuations, encompassing applications such as gas sensing, bolometer imaging and industrial process monitoring. The micro-thermistor gas pressure sensor assembly includes a suspended platform micro-thermistor sensor device exposed to the gas pressure of a given atmospheric environment, an electrical readout circuit connected to the suspended platform micro-thermistor sensor device, wherein the suspended platform micro-thermistor sensor device acts as a variable electrical resistance in the readout electrical circuit, a binary-wave voltage source connected to the suspended platform micro-thermistor sensor device, and an ohmmeter.

Abstract: A pirani vacuum gauge in which a response to a rapid pressure rise is improved and restrictions on a mounting direction of a container on a chamber to be measured for pressure are eliminated is provided. The Pirani vacuum gauge includes a heat filament of metal wire and a support unit for supporting the heat filament in a container, wherein a gas pressure is measured based on an amount of heat conducted away from the heat filament by gas molecules colliding with the heat filament, characterized in that a body of the container is filled with metal material, but a first cylindrical bore and a second cylindrical bore extend through the body, the heat filament being inserted into the first cylindrical bore and the support unit being inserted into the second cylindrical bore.

Abstract: A Pirani vacuum gauge in which a response to a rapid pressure rise is improved and restrictions on a mounting direction of a container on a chamber to be measured for pressure are eliminated is provided. The Pirani vacuum gauge includes a heat filament of metal wire and a support unit for supporting the heat filament in a container, wherein a gas pressure is measured based on an amount of heat conducted away from the heat filament by gas molecules colliding with the heat filament, characterized in that a body of the container is filled with metal material, but a first cylindrical bore and a second cylindrical bore extend through the body, the heat filament being inserted into the first cylindrical bore and the support unit being inserted into the second cylindrical bore.

Abstract: A Pirani vacuum gauge in which dependency of temperature of a filament on variation of gas pressure is raised and the gas pressure can be measured with high accuracy. The Pirani vacuum gauge includes a cylindrical body 2 in which the interior communicates with a space to be measured for pressure; a filament 1 enclosed in the cylindrical body 2; and a pipe 7 surrounding the filament 1 in the cylindrical body, the least distance between the facing inner walls of the pipe being equal to less than 6 mm and the pipe 7 covering more than 80% of the length of the filament 1.

Abstract: A Pirani vacuum gauge in which a response to a rapid pressure rise is improved and restrictions on a mounting direction of a container on a chamber to be measured for pressure are eliminated is provided. The Pirani vacuum gauge includes a heat filament of metal wire and a support unit for supporting the heat filament in a container, wherein a gas pressure is measured based on an amount of heat conducted away from the heat filament by gas molecules colliding with the heat filament, characterized in that a body of the container is filled with metal material, but a first cylindrical bore and a second cylindrical bore extend through the body, the heat filament being inserted into the first cylindrical bore and the support unit being inserted into the second cylindrical bore.

Abstract: A Pirani pressure gauge comprises a heated, coiled sensing element formed from an alloy comprising platinum and iridium, for example, 90/10 Pt/Ir. This enables the gauge to be deployed in a corrosive environment and reliably measure pressures as low as 10?4 mbar over a prolonged period of time.

Abstract: A system for determining a gas pressure or gauging a vacuum in a hermetically sealed enclosure. One or more heater structures and one or more temperature sensor structures situated on a substrate may be used in conjunction for measuring a thermal conductivity of a gas in the enclosure. Each heater has significant thermal isolation from each sensor structure. Electronics connected to each heater and sensor of their respective structures may provide processing to calculate the pressure or vacuum in the enclosure. The enclosure may contain various electronic components such as bolometers.

Abstract: A Pirani vacuum gauge in which dependency of temperature of a filament on variation of gas pressure is raised and the gas pressure can be measured with high accuracy. The Pirani vacuum gauge includes a cylindrical body 2 in which the interior communicates with a space to be measured for pressure; a filament 1 enclosed in the cylindrical body 2; and a pipe 7 surrounding the filament 1 in the cylindrical body, the least distance between the facing inner walls of the pipe being equal to less than 6 mm and the pipe 7 covering more than 80% of the length of the filament 1.

Abstract: A vacuum gauge of the Pirani type for measuring the pressure of vaporized organic or inorganic material used in forming a layer of a device, comprising: an extended filament having a thickness of 5 microns or less and having a temperature coefficient of resistance greater than 0.0035/° C., the filament being subject to the vaporized organic or inorganic material; means for applying a current to the filament so that the temperature of the filament is less than 650° C. so as not to degrade the molecular structure of the organic material; and a structure responsive to a change in resistance or a change in current to determine heat loss from the filament, which is a function of the pressure of the vaporized organic or inorganic material.

Abstract: The present invention provides a pressure sensor. The pressure sensor comprises a substrate with several support structures attached to the substrate. The pressure sensor further includes a strut structure integrated with a heating element. The strut structure is engaged with the support structures so as to create an air gap between the heating element and the substrate. The heating element has an electrical resistance proportional to changes in air pressure in the air gap.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and has temperature response and physical characteristics substantially matching those of the resistive sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element for applying current to heat the sensing element relative to the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and has temperature response and physical characteristics substantially matching those of the resistive sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element for applying current to heat the sensing element relative to the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: A pressure sensor has a baseplate and a support plate with a membrane. Layers on the membrane and the support plate are connected to a circuit for capacitively measuring pressure to generate a first pressure signal. A thermal conductivity measuring element that generates a second pressure signal has a heating element connected to the baseplate adjacent the support plate at a location opposite from the membrane for protecting the membrane from thermal effects. The method uses the sensor apparatus to generate an output signal representing a measured result when the measured result is above a transition value, on the basis of the first pressure signal and, when the pressure falls below a threshold value, any offset of the first pressure signal is compensated in such a way that determination of the output signal on the basis of the first pressure signal leads to the same result as determination of the output signal on the basis of the second pressure signal.

Abstract: A pressure transducer assembly includes a transducer member supporting a transducer element for measuring pressure within an environment. The transducer member has a sealing surface surrounding the transducer element. A housing having an integral resilient member resiliently supports the transducer member and exerts a sealing force on the transducer member against a mating member secured to the housing.

Abstract: A digital pressure gauge comprises a power supply, an input button unit, a pressure sensor, a display unit, a warming unit, and a control unit. The control unit counts an operation times and/or operation duration of the digital pressure gauge and generates alarm through the display unit and the warming unit when the counted operation times and/or operation duration of the digital pressure gauge exceeds a threshold.

Abstract: A vacuum gauge of the cold cathode type has a gauge head which includes a cathode discharge cell and an anode a portion of which is located within the cathode discharge cell. An electrically operated ignition device is located adjacent the cathode discharge cell which ignition device is protected from being operated at high pressure by an auxiliary pressure sensor.

Abstract: Two resistance elements (3, 6) are used for eliminating the influence of wall temperature on the gas pressure in a vessel, determined by a Pirani manometer. The first resistance element (3) is present in a first branch of a Wheatstone bridge (1), and the voltage is tapped by means of a voltage divider (7). The second resistance element (6) is present with a series resistance (5) in the second branch and is adjusted to a lower temperature. The changes in the voltages tapped at the branches are essentially identical for identical temperature changes at the resistance elements (3, 6), so that the Wheatstone bridge (1) remains balanced. The adjustment is improved by a constant current source (11).

Abstract: A pressure gauge device that is operated as a thermal conduction manometer contains a measuring resistor (131) that is arranged in layer form on a self-supporting carrier foil and is in defined thermal contact with a gas whose pressure is to be measured. The thermal contact with the gas is through the carrier foil (11), a thermal conducting layer (123) and optionally through an extra absorber layer (124). The resistance, dependent on gas pressure, of the measuring resistor (131) is detected by a bridge circuit in which each measuring resistor (131) is assigned a reference resistor (136) whose resistance itself is dependent on or independent of pressure.

Abstract: An improved Pirani gauge has a small-diameter wire sensing element, coplanar with a small-diameter wire compensating element, with two parallel flat thermally conductive plates spaced from the sensing and compensating elements. The sensing and compensating elements and their connections have the same physical dimensions, thermal properties and resistance properties. The connections have large thermal conductances to a uniform temperature region and the elements are located in the same vacuum environment. A DC heating current is used and confined to only the sensing element. A relatively small AC signal is used to sense bridge balance. A simplified three-dimensional pressure compensation formula provides accurate compensation while simplifying the collection of calibration data. The improved gauge provides significant advancements in Pirani gauge accuracy, production cost, and package size.

Abstract: An improved Pirani gauge has a small-diameter wire sensing element, coplanar with a small-diameter wire compensating element, with two parallel flat thermally conductive plates spaced from the sensing and compensating elements. The sensing and compensating elements and their connections have the same physical dimensions, thermal properties and resistance properties. The connections have large thermal conductances to a uniform temperature region and the elements are located in the same vacuum environment. A DC heating current is used and confined to only the sensing element. A relatively small AC signal is used to sense bridge balance. A simplified three-dimensional pressure compensation formula provides accurate compensation while simplifying the collection of calibration data. The improved gauge provides significant advancements in Pirani gauge accuracy, production cost, and package size.

Abstract: An apparatus (10) allows atmospheric pressure into an environmentally sealed enclosure for creating an equilibrium that allows a sensor (28) make a proper measurement. A slot or opening (26) in the cover (14) exposes outside atmospheric air to a restricted portion of a gas permeable membrane (18). The membrane (18) allows a selected gas to pass through the membrane (18) creating the equilibrium in the housing (12). A gasket (16) positioned between the cover (14) and housing (12) seals the housing in an air tight manner except for the gases allowed in through the membrane (18). Pressure sensor (28) can then make a more accurate measurement. Apparatus (10) finds particular utility in a low pressure tire management system.

Abstract: In order to cover a large measuring range extending from about 10.sup.-6 mbar to about 10 bar, a simple, compact and economically producible pressure sensor (3) arranged in a protective tube (1) has, on a support plate (5), a ceramic membrane (6) which, together with the support plate (5), forms a capacitive measuring element for the determination of pressures between about 0.1 mbar and 10 bar, and two measuring wires (11, 12) which are arranged adjacent to the membrane (6) and constitute a Pirani measuring element with substantial compensation of the effect of the wall temperature, for the determination of pressures between about 10.sup.-6 mbar and 1 mbar. The membrane (6) is shielded from the radiation of the measuring wires (11, 12) by a protective ring (16).

Abstract: The invention relates to a process for operating a controlled heat conductance vacuum gauge with a measuring cell (18) comprising a Wheatstone bridge (1) with supply voltage (12, 13) and measurement voltage terminals (14, 15), a power supply and measuring instrument (21) and a connecting cable (19) containing several conductors and to a circuit therefor; in order to prevent errors of measurement caused by connecting cables (19) of different lengths and to automate cable length equalization it is proposed that the voltage of a power supply terminal (12, 13) of the Wheatstone bridge (1) in the measuring cell (18) be recorded without current via one (26) of the conductors of the connecting cable (19) and taken into account in the formation of the measurement value.

Abstract: The invention is a method and apparatus for a pirani pressure sensor. The apparatus consists of a current supply and current receiving means affixed to a substrate. Bridging the current supply means and current receiving means is an electrically conductive polymer. The pirani pressure sensor may be made using conventional photolithographic techniques.

Abstract: The invention relates to a process for operating a regulated heat conduction vacuum gauge with a Wheatstone bridge (1) powered by a controllable supply voltage and a gauge filament (6) and a resistance (9) as two of its components among others, designed to be temperature-dependant to compensate for interference effects of the ambient temperature on the gauge filament (6) and to a suitable circuit for implementing this process; it is proposed, in order to improve and simplify the temperature compensation, that, by linking various electrical measurements of the bridge (1) or by equivalent approximation systems, the value or the temperature of the temperature-dependant resistance (9) be found and taken into account in determining the pressure measurements (drawing FIG. 2).

Abstract: A microvacuum sensor has an expanded sensitivity range, wherein a thin membrane having poor thermal conductivity is freely suspended on a semiconductor single-crystal. A thin metallic heating layer, preferably of aluminum, is arranged on the membrane. The membrane surface is suspended by at least one web of the membrane material. The heating layer has an extremely low emissivity of less than 0.1 in the near infrared range. A film resistor having the same temperature coefficient as the metallic heating layer is arranged on the sensor chip in the region of the solid silicon for temperature compensation of temperature fluctuations. Members having a planar mirrored wall are arranged parallel to the surfaces of the membrane at a spacing of less than 5 .mu.m from the membrane. These members act as a heat sink relative to the membrane. Gas from the environment of the sensor can freely circulate between the membrane and the wall surfaces.

Abstract: Particularly for the combination of cold-cathode ionization sensors and Pirani sensors, for obtaining a one-to-one measuring range which is significantly expanded compared to the measuring ranges of the respective sensor types, a weighting technique is provided in a transition range .DELTA.P of the respective sensor measuring ranges by which the characteristic sensor curves can constantly be guided into one another in a one-to-one manner.

Abstract: A miniaturized silicon based thermally controlled vacuum sensor uses thin film resistors on a membrane in a minute measuring chamber to accurately detect vacuum pressures in the range of 760 Torr to 1.times.10.sup.-5 Torr. The configurations of the measuring chamber and gas diffusion port of the sensor structure insure that heat transfer from the membrane is predominately conductive over the pressure detection range to provide linear output up to 0.1 Torr. A microprocessor is used to control and measure power required to maintain a predetermined temperature differential between a sensing resistive element on the membrane and an ambient temperature sensing element of the sensor base from analog voltage and current values. Pressure detection errors introduced by ambient temperature variations are minimized by measuring power dissipated into the gas. Analog and digital converters for both current and voltage signals use a .SIGMA.-.DELTA.

Abstract: A method and apparatus for convening a measured signal which, at least in a first approximation, is related to a quantity of interest by the equation (a): ##EQU1## where y is the quantity of interest, x is the measured signal, and k, k.sub.N, k.sub.Z are constants, into a signal that is a function of the quantity of interest. The method implements the function (b):ln y=prop. ([ln (x-k.sub.N)-ln (k.sub.Z -x)])wherein prop. means proportional, and where the function is implemented in an approximated manner by at least two bipolar transistors that have base emitter voltages that are dependent on collector currents of the bipolar transistors for receiving an output signal according to the equation (c): y'=ln y, with y' being the output signal.

Abstract: A thermocouple vacuum gauge includes a first thermocouple element spaced below a second thermocouple element. The two thermocouple elements are electrically connected in series in a back-to-back manner by connecting together their respective negative ends. A pulse generator supplies a pulsing on-off current only to the first thermocouple element. During the off intervals, a switch connects the positive ends of both thermocouple elements to a voltage measuring and comparing circuit which measures a thermally generated voltage signal between the positive ends of the thermocouple elements and compares the measured voltage signal to a reference signal. The result of the comparison is used to vary the output current of the pulse generator so as to supply an amount of current to the first thermocouple element sufficient to cause the measured voltage signal to approach the reference signal.

Abstract: A new structure of a vacuum meter with good designs of temperature compensation and stabilization, The structure comprises a floating plate made by a micro-machining technique and a thermal sensitive element installed on the floating plate, The floating plate has a number of suspending arms extending outward to supporting the floating plate in a cavity of a semiconductor substrate for good heat isolation. The area of the floating plate and the length and width of the suspending arm has a specific ratio for an optimized sensitivity. A dummy resistor for temperature compensation is composed by a serial connection of a constant resistor with almost zero temperature coefficient and the thermal sensitive elements in a specific ratio. The vacuum meter further overlap on a temperature-controlled thermoelectric cooling device and is covered by a thermal shield so that the temperatures on and circumferential to the floating plate can be maintained stably.

Abstract: The present invention provides a vacuum gauge having two integrated circuits connected in a half bridge circuit to register subatmospheric gas pressure from a change in thermal gas conductivity. One of the integrated circuits serves to generate an electrical current proportional to the ambient temperature and a function of its power output conducted by the gas. The other of the integrated circuits acts as a reference to generate an electrical current proportional to ambient temperature. The half bridge circuit acts to subtract the currents so that subatmospheric pressure can be read on an ammeter as a function of gas thermal conductivity.

Abstract: A vacuum gauge for measuring pressure of environmental gas includes a quartz resonator disposed in the gas, and undergoing oscillation having a resonant frequency dependent on its body temperature which is dependent on relatively low pressure and having a resonant current which is dependent on relatively high pressure. Heat source is disposed adjacent to the resonator for supplying heat to the resonator so as to maintain the body temperature thereof and resonant frequency thereof according to the pressure of environmental gas, and producing an first output signal representative of value of the pressure in relatively low pressure range. A converter converts the resonant current of resonator into a corresponding second output signal representative of value of the pressure in relatively high pressure range. A meter indicates the value of pressure according to the first and second output signals.

Abstract: A process for measuring pressure, preferably vacuum is described. The measuring signals from a heat conduction gauge and the measuring signals from a gas friction gauge are processed to a common measuring signal preferably by multiplication. They are linearly superimposed or added. The heat conduction gauge is preferably a Pirani gauge and the gas friction gauge is preferably a tuning fork quartz gauge.

Abstract: A pressure or vacuum gauge measures pressure of gas within a chamber. A quartz oscillator is disposed within the chamber for undergoing oscillation having a frequency dependent on a body temperature thereof. A constant heat source is disposed in spaced relation to or directly on the temperature-dependent quartz oscillator for heating the same to hold the body temperature thereof which is dependent on the pressure of surrounding gas. The oscillating frequency of the quartz oscillator is converted into a signal indicative of the pressure of the gas.

Abstract: A pressure differential measuring apparatus (25) wherein the direction of fluid flow (5) is determined by calculating the ratio between pressures of two discrete fluid masses (3, 4). The device includes two tandem thermal sensors (7, 6), the upstream sensor creating a thermal wake which is carried past the downstream sensor, thereby slowing the downstream sensor's nominal cooling rate. A venturi (8) is utilized to create desired flow characteristics in the region of the sensors.

Abstract: A conduction-responsive meter head has a device having electrical conduction responsive to a condition such as pressure to be metered. The device communicates with the condition to provide its electrical-conduction response to a bridge electrically including the device. A power supply has two terminals on the meter head for providing electrical power to the bridge. The measurement signal from the bridge is provided, however, to a third terminal by a lead from the bridge.