Since late 1960’s, the capacitance manometer is widely used. Deflections of the diaphragm as small as 10-10 m can be sensed.The corresponding pressure change is 10-6 torr.

Thermal Conduction GaugesThermal conductivity gauges operate in the pressure range where the energy transport in the gas phase between two elements at different temperatures take place by gaseous conduction.

At higher pressure convection becomes the dominant transport mechanism. At pressure below the operating range of thermal conduction gauges, energy is primarily transported by irradiation and possible conduction along elements.

Ii = Ie × S × P Ii = ion current Ie = electron currentP = pressure (Pa) S = sensitivity (Pa-1)