At common so-called mechanical vacuum gauges (BOURDONVAC, DIAVAC, capsule vacuum gauges) the pressure is determined directly by recording the force acting on the surface of a diaphragm. In this case of direct (or absolute) pressure measurements, the readings obtained through the vacuum gauge are independent of the type of gas and the pressure which is to be measured. The pressure range is approx. from 1000 mbar (atmospheric pressure, 750 Torr) to 1 mbar (0,75 Torr).