Gas Sonic Velocity calculation

Piping Systems
Equivalent length key pipe components
Singularity coefficient key pipe components
Partially filled pipe
Sonic Velocity
Valves types
Valves Cv
Control valve sizing for gases
Pressure safety valves
Colebrook correlation
Churchill correlation
Velocity in pipes
Flow regimes
Orifice calculations

1. Introduction

Calculating the sonic velocity is necessary for different design activities. It is also handy to be able to determine under which pressure drop a gas flow will reach sonic conditions.

2. Sonic Velocity Calculation

Vs = (K g R T)0.5
With :
Vs = Sonic velocity (ft/s)
K = Cp/Cv around 1.4 for most diatomic gases
g = 32.2 ft/s2
R = 1544 mol
T = Absolute temperature (°R)

3. Critical pressure ratio

[2/(K+1)]K/(K-1)

K = Cp/Cv around 1.4 for most diatomic gases


Source
[1] Rules of Thumbs for Chemical Engineers, Brannan, Gulf, 2005