What is a Torr gauge?
A Torr gauge is an absolute pressure gauge and operates on the principle of an altimeter. The Gauge case is evacuated by the vacuum from the process and exerts a negative pressure on a hermetically sealed capsule. The lowering of the pressure in the gauge case causes the capsule to expand thereby causing the gauge movement to turn the pointer. The Torr gauge is highly sensitive and accurate in the lower pressure regions (0-100 mm Hg).