Absolute Pressure

Absolute pressure is a particular type of pressure measurement which is relative to the zero pressure in the empty, air-free space of the universe. This reference pressure is the ideal or absolute vacuum. This is why this measurement is independent of environmental influences such as weather or altitude.

Absolute pressure in fluids cannot be negative, and the smallest absolute pressure is zero. This type of pressure can be measured using an electronic diaphragm sensor, where the measured pressure is applied on one side of the diaphragm, while the other side of the diaphragm is exposed to a permanently sealed vacuum.

Absolute pressure ranges are often labelled with an ‘abs’ or ‘a’ suffix to the pressure units proceeding a pressure value, e.g. 1013.25 mbar abs or 1013.25 mbara.

Absolute pressure is the sum of gauge pressure and atmospheric pressure.