Air compression and expansion
Compressed air in industry

It varies from place to place. Pure, dry air can be considered a perfect gas because its components are, at the pressures generally used, far from the critical point (≈ 150 K and 50 bar). This is the ideal case.

The physical constants of typical dry air, as defined by the International Civil Organization (ICAO), are as follows:

• molar mass: M = 28.9644 kg/kmol ;

• atmospheric pressure at sea level: 101 325 Pa ;

• temperature at sea level: 15 °C ;

• density at sea level: 1.225 kg/m ³ ;

• universal perfect gas constant: R...