4th December 2019

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# What is absolute barometric pressure?

Absolute pressure is measured relative to a full vacuum. Alternatively, pressure that is measured against atmospheric pressure (also known as barometric pressure) is called gauge pressure. A full vacuum has an absolute pressure reading of 0 PSIA and average barometric pressure at sea level is ~14.7 PSIA.

Similarly, it is asked, what is the gauge pressure?

Gauge pressure is a relative pressure measurement which measures pressure relative to atmospheric pressure and is defined as the absolute pressure minus the atmospheric pressure. Most pressure measuring equipment give the pressure of a system in terms of gauge pressure as opposed to absolute pressure.

What does it mean to have negative gauge pressure?

Vacuum pressure is also measured relative to the local atmospheric pressure, but is used when the gage pressure is negative, i.e. when the absolute pressure falls below the local atmospheric pressure. (Positive vacuum pressure means that the gage pressure is negative.)