# Reynolds Number for Gas

on . Posted in Fluid Dynamics

## Reynolds Number for Gas Formula

$$\large{ Re = 20,100 \; \frac{ SG \; Q }{ d \; \eta } }$$
Symbol English Metric
$$\large{ Re }$$ = Reynolds number $$\large{ dimensionless }$$
$$\large{ Q }$$ = flow rate of gas $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$
$$\large{ SG }$$ = gas specific gravity relative to water (water = 1) $$\large{ dimensionless }$$
$$\large{ d }$$ = inside diameter of pipe $$\large{ in}$$ $$\large{ mm }$$
$$\large{ \eta }$$  (Greek symbol eta)  = viscosity of gas $$\large{\frac{lbf - sec}{ft^2}}$$ $$\large{Pa-s}$$