IATA Class 2 Gases

According to the DGR, a gas is defined as "a substance which at 50° C (122° F) has a vapor pressure greater than 300 kPa (3.0 bar) or is completely gaseous at 20° C (68° F) at a standard pressure of 101.3 kPa (1.01 bar)."

There are five physical states of gas, when packaged under pressure for transport, described as follows:

Compressed gas is entirely gaseous at -50° C (-58° F). This includes all gases with a critical temperature less than or equal to -50° C (-58° F).

Liquefied gas is partially liquid at temperatures above -50° C (-58° F). High-pressure liquefied gases have a critical temperature between -50° C (-58° F) and +65° C (149° F). Low-pressure liquefied gases have a critical temperature above +65° C (149° F).

Refrigerated liquefied gas is made partially liquid because of its low temperature. This is also referred to as cryogenic liquid.

Dissolved gas is dissolved in a liquid phase solvent.

Absorbed gas is absorbed into a solid porous material that results in an internal receptacle pressure of less than 101.3 kPa at 20° C (68° F) and less than 300 kPa at 50° C (122° F).

Class 2 dangerous goods include compressed gases, liquefied gases, absorbed gases, dissolved gases, refrigerated liquefied gases, mixtures of one or more gases (even if one or more vapors is from a different class), articles charged with a gas, and aerosols.

To learn more about IATA Dangerous Goods Regulations visit our IATA DGR Online Training Certification Courses web page.