# Specific Gravity of Gas

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

## Specific Gravity of Gas formula

$$G = \frac{\rho_g} {\rho_a}$$

$$G = \frac{M_g} {M_a}$$

Where:

$$G$$ = gas gravity

$$\rho_g$$ = density of the gas, dimensionless $$\;\left( \frac{lb}{ft^3}\right)$$

$$\rho_a$$ = density of the air, dimensionless $$\;\left( 0.075 \frac{lb}{ft^3}\right)$$

$$M_g$$ = molecular weight of the gas

$$M_a$$ = molecular weight of air, dimensionless (28.9625)