What is pirani gage?

A Pirani gauge is a type of pressure gauge used to measure low pressures in vacuum systems. It works based on the thermal conductivity of gases, which decreases as pressure decreases. The gauge consists of a heated filament that is sealed within a cylindrical glass or metal tube. When a vacuum is created in the tube, the filament loses heat to the gas molecules present in the tube. The rate of heat loss is a function of the pressure in the tube, and this information can be used to calculate the pressure using a calibrated scale. The Pirani gauge is widely used in a variety of industries, including semiconductor manufacturing, aerospace, and scientific research. It is a cost-effective and reliable method for measuring low vacuum pressures.