Pressure sensing apparatus in which a mounting structure carrying a thin, pressure sensitive resistance wire is lodged in a gas passageway extending through an outer member. The mounting includes a relatively large end portion which extends substantially across the passageway to both shield the wire from direct impact by passing gas, and limit the flow of such gas by occluding the passageway. The secure wire mounting apparatus makes possible the use of very thin wires and a corresponding increase in pressure sensitivity resulting from temperature and gas thermal conductivity. The wire diameter is no more than about 0.00005 inch, making possible results comparable to much more expensive mass spectrometer techniques. An overall pressure sensing system is described in which the sensor is coupled with electric circuitry to produce transient and/or absolute pressure readings over an approximately nine decade pressure range. Transient readings of gas temperature and thermal conductivity may also be made.
A measuring head for a vacuum gauge. An essentially cylindrical housing encloses a measuring cell which is sealed in a vacuum tight manner against the surrounding atmosphere and is connectable with an evacuatable cavity. A measuring filament for producing an electrical signal corresponding to the pressure in the measuring cell is disposed in the measuring cell. The measuring filament is disposed approximately perpendicularly to the axial direction of the housing.
A density monitoring assembly for use in monitoring the gas density within a high voltage circuit breaker tank is disclosed. The density monitoring assembly is coupled directly to an exterior surface of said tank and provides electrical signals indicative of the density of gas within the tank. The assembly comprises a cover that encloses the density monitoring device. The device itself is used to retain the cover. A ball valve and a shraeder type valve are provided to allow testing of the device.
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.
The output characteristics of the sensing device or the control quantity of the sensing element can be adjusted by extracting an adjusting terminal in addition to a power source terminal, a ground terminal, an output terminal and the like outside a housing containing and protecting an electronic circuit. Further, by arranging the adjusting terminal inside a connector housing containing terminals such as the power source terminal, the ground terminal, the output terminal and the like, it is possible to prevent contact of foreign objects to the adjusting terminal and to water-proof the terminals for preventing corrosion since an associated connector is attached to the connector when the sensing device is actually used.
The output characteristics of the sensing device or the control quantity of the sensing element can be adjusted by extracting an adjusting terminal in addition to a power source terminal, a ground terminal, an output terminal and the like outside a housing containing and protecting an electronic circuit. Further, by arranging the adjusting terminal inside a connector housing containing terminals such as the power source terminal, the ground terminal, the output terminal and the like, it is possible to prevent contact of foreign objects to the adjusting terminal and to water-proof the terminals for preventing corrosion since an associated connector is attached to the connector when the sensing device is actually used.
