Pirani gauge
About Pirani gauge
Pirani gauge is similar to a
thermocouple gauge but has a heated element which consists of four
coiled tungsten wires connected in parallel. Two identical tubes are
normally used, connected in a bridge circuit with one containing the
gas at unknown pressure and the other evacuated to a very low
pressure. Current is passed through the tungsten element, which
attains a certain temperature according to the thermal conductivity of
the gas. The resistance of the element changes with temperature and
causes an imbalance of the measurement bridge. Thus the Pirani gauge
avoids the use of a thermocouple to measure temperature (as in the
thermocouple gauge) by effectively using a resistance thermometer as
the heated element. Such gauges cover the pressure range 10-5
mbar to 1 mbar.
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Pressure Measurements
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