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CLASS 2 GASES
2.1 A gas is a substance which:
.1 at 50°C has a vapour
pressure greater than 300 kPa; or
.2 is completely gaseous at 20°C at a standard pressure of 101.3 kPa.
2.2. The transport condition of gas is described according to its physical state as:
.1 Compressed gas - a gas (other than in solution) which, when packaged under pressure for transport, is entirely gaseous at 20°C;
.2 Liquefied gas - a gas which, when packaged for transport, is partially liquid at 20°C;
.3 Refrigerated liquefied gas - a gas which, when packaged for transport, is made partially liquid because of its low temperature; or
Refrigerant means a gas used as a cooling substance in the refrigeration process, such as refrigerating machinery UN 2857 in this case.
.4 Gas in solution - compressed gas which, when packaged for transport, is dissolved in a solvent.
2.2.1 This class comprises compressed gases; liquefied gases; gases in solution; refrigerated liquefied gases; mixtures of gases; mixtures of one or more gases with one or more vapours or substances of other classes; articles charged with a gas; tellurium hexafluoride; aerosols.
2.3 Class subdivisions
Class 2 is subdivided further according to the primary hazard of the gas during transport, namely:
2.3.1 Class 2.1 Flammable gases
Gases which at 20°C and a standard pressure of 101.3 kPa:
.1 are ignitable when in a mixture of 13% or less by volume with air; or
.2 have a flammable range with air of at least 12 percentage points regardless of the lower flammable limit. Flammability should be determined by tests or calculation in accordance with methods adopted by the International Organization for Standardization (see ISO standard 10156:1996). Where insufficient data are available to use these methods, tests by a comparable method recognized by a national competent authority may be used.
Note: UN 1950 AEROSOLS and UN 2037 RECEPTACLES, SMALL, CONTAINING GAS (GAS CARTRIDGES) should be regarded as being in class 2.1 when the criteria in Special Provision 63 in 3.3.1 of IMDG Code 2000 Edition are met.
2.3.2 Class 2.2 Non-flammable, non-toxic gases
Gases which are transported at a pressure not less than 280 kPa at 20°C, or as refrigerated liquids, and which:
.1 are asphyxiant - gases which dilute or replace the oxygen normally in the atmosphere; or
.2 are oxidizing - gases which may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does; or
.3 do not come under the other classes.
2.3.3 Class 2.3 Toxic gases
Gases which:
.1 are known to be so toxic or corrosive to humans as to pose a hazard to health; or
.2 are presumed to be toxic or corrosive to humans because they have a LC50 value (as defined in 2.6.2.1 of IMDG Code 2000 Edition) equal to or less than 5,000 ml/m3 (ppm).
Note: Gases meeting the above criteria owing to their corrosivity are to be classified as toxic with a subsidiary corrosive risk.
