# Reynolds Number for Gas

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

### Reynolds Number for Gas Formula

$$\large{ Re = 20,100 \; \frac{ SG \; Q_g }{ d \; \eta } }$$

Where:

$$\large{ Re }$$ = Reynolds number

$$\large{ Q_g }$$ = flow rate of gas

$$\large{ SG }$$ = gas specific gravity relative to water (water = 1)

$$\large{ d }$$ = pipe inside diameter

$$\large{ \eta }$$  (Greek symbol eta)  = viscosity of gas