# Absolute Pressure

A pressure at absolute zero can only exist in a total vacuum and any pressure above this is called absolute pressure. Absolute pressure, abbreviated as \(p_a\), is the amount by which the measured pressure exceeds a perfect vacuum. It is specified as psia. Absolute pressure is equal to 0 psia or -14.7 psig.

\(\large{ p_a = p_g + p_{atm} }\) \(\large{ p_a = p_g + p_v }\) Where: \(\large{ p_a }\) = absolute pressure \(\large{ p_g }\) = gauge pressure \(\large{ p_{atm} }\) = atmospheric pressure \(\large{ p_v }\) = vacuum pressure Solve for: \(\large{ p_g = p_a - p_{atm} }\) \(\large{ p_{atm} = p_a - p_g }\) |

Tags: Equations for Pressure