Pirani Gauge working principle, application & advantages

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here we know Pirani gauge application, Pirani gauge working principle and advantages of the Pirani gauge. here we take complete information about Pirani Gauge.

Pirani gauge application

Pirani gauge is a device used to measure pressure in the pressure range from 0.5 Torr to 10−4 Torr.

Pirani Guage working principle

pirani gauge circuit

The Pirani gauge consists of a metal filament (usually platinum ) suspended in a tube which is connected to the system whose vacuum is to be measured. The connection is usually made either by a ground glass joint or flanged metal connector, sealed with an o- ring. The filament is connected to an electrical circuit from which, after calibration, a pressure reading may be taken.

A conducting wire (platinum filament) gets heated when electric current flows through it. This wire suspended in a gas will lose heat to the gas as its
molecules collide with the wire and remove heat. As the gas pressure is reduced the number of molecules present will fall proportionately, the conductivity of the surrounding media will fall and the wire will lose heat more slowly.

Measuring the heat loss is an indirect indication of pressure.

The electrical resistance of the wire varies with its temperature, so the measurement of resistance also indicates the temperature of the wire. Now the change in resistance of the filament is determined using the bridge.

This change in resistance of the Pirani gauge filament becomes a measure of the applied pressure when calibrated. The gauge may be used for pressures between 0.5 Torr to 10 − 3 Torr. The thermal conductivity and heat capacity of the gas may affect the readout from the meter, and therefore the apparatus may need calibrating before accurate readings are obtainable. For lower pressure measurement other instruments are used.

Advantages of Pirani gauge

>> These gauges are rugged, inexpensive and usually more accurate than thermocouple gauge.

>> Pressure reading range is wider.

>> Fast response to the change in pressure.

>> The possibility of process control and remote reading.

Disadvantages of Pirani gauge

>> Calibration is non-linear and varies from one gas to another.

>> Require calibration against some pressure standards.

>> Poor transient response.

>> Operation requires electrical power.

conclusion

Hope now you know everything about Pirani gauge. Pirani gauge is used for measuring pressure. In the previous article, we also see different pressure transducers which are used for pressure measurement. here we cover Pirani gauge. if you have any doubt regarding this article kindly comment below.


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