Pure gases, gas mixes, and also mixes of gases with liquid or rigid substances belong to this class. Gases can be nonflammable and flammable, chemically stable and unstable, toxic and nonpoisonous in any combination of these properties.
The main danger of gases directly depends on their pressure. The compressed and liquefied gases with a critical temperature about 20 °C, the cooled liquefied gases, gases dissolved under pressure or in solvent, and also aerosol sprays, and also any products containing gas under pressure can be very dangerous.
- Division 2.1: Non-flammable, non-toxic gases
- Division 2.2: Toxic gases
- Division 2.3: Flammable gases
- Division 2.4: Flammable and toxic gases