p1

(bar) Input pressure (relative atmosphere)

p2

(bar) Output pressure (relative atmosphere)

p1_{abs}

(bar) Input absolute pressure

p2_{abs}

(bar) Output absolute pressure

b

Critical pressure ratio Ratio of output pressure p2_{abs} and input pressure p1_{abs} which marks the transition from choked flow (sonic velocity in narrowest section) to subsonic flow

C

The Cvalue (l/(s*bar)). Flow sonic conductance Ratio of volume flow Q and input pressure p1_{abs} for choked flow C=Q/p1_{abs}
