IMO Classes for Dangerous Goods
Subclass 2.1 - Flammable Gas
454 kg (1001 lbs) of any material which is a gas at 20°C (68°F) or less and 101.3 kPa (14.7 psi) of pressure (a material which has a boiling point of 20°C (68°F) or less at 101.3 kPa (14.7 psi)) which:
1. Is ignitable at 101.3 kPa (14.7 psi) when in a mixture of 13 percent or less by volume with air; or
2. Has a flammable range at 101.3 kPa (14.7 psi) with air of at least 12 percent regardless of the lower limit.
Subclass 2.2 - Non-flammable, Non-poisonus Gas
This division includes compressed gas, liquefied gas, pressurized cryogenic gas, compressed gas in solution, asphyxiant gas and oxidizing gas. A non-flammable, nonpoisonous compressed gas (Division 2.2) means any material (or mixture) which:
1. Exerts in the packaging an absolute pressure of 280 kPa (40.6 psia) or greater at 20°C (68°F), and
2. Does not meet the definition of Division 2.1 or 2.3.
Subclass 2.2 - Oxygen Gas
This is an optional placard to the 2.2 Non-flammable Gas placard for compressed Oxygen in either the gas or liquid state. Oxygen is considered a non-flammable because it in and of itself does not burn. It is, however, required for combustion to take place. High concentrations of oxygen greatly increases the rate and intensity of combustion.
Subclass 2.3 - Poison Gas
Gas poisonous by inhalation means a material which is a gas at 20°C or less and a pressure of 101.3 kPa (a material which has a boiling point of 20°C or less at 101.3kPa (14.7 psi)) and which:
1. is known to be so toxic to humans as to pose a hazard to health during transportation, or
2. in the absence f adequate data on human toxicity, is presumed to be toxic to humans because when tested on laboratory animals it has an LC50 value of not more than 5000 ml/m³.