Density, Specific Weight and Specific Gravity
NTP Normal Temperature and Pressure defined as 20 o C ( K, 68 o F) and 1 atm ( kN/m2, kPa, psia, 0 psig, 30 in Hg, 760 torr); Molecular weights can be used to calculate Specific Gravity if the densities of the gas and the air are evaluated at