Absolute Pressure

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

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