Hazardous materials classes and index to hazard class definitions.

The hazard class of a hazardous material is indicated either by its class (or division) number, its class name, or by the letters “ORM-D”. The following table lists class numbers, division numbers, class or division names and those sections of this subchapter which contain definitions for classifying hazardous materials, including forbidden materials.

Class No. Division No. (if any) Name of class or division 49 CFR reference for definitions None Forbidden materials 173.21 None Forbidden explosives 173.54 1 1.1 Explosives (with a mass explosion hazard) 173.50 1 1.2 Explosives (with a projection hazard) 173.50 1 1.3 Explosives (with predominately a fire hazard) 173.50 1 1.4 Explosives (with no significant blast hazard) 173.50 1 1.5 Very insensitive explosives; blasting agents 173.50 1 1.6 Extremely insensitive detonating substances 173.50 2 2.1 Flammable gas 173.115 2 2.2 Non-flammable compressed gas 173.115 2 2.3 Poisonous gas 173.115 3 Flammable and combustible liquid 173.120 4 4.1 Flammable solid 173.124 4 4.2 Spontaneously combustible material 173.124 4 4.3 Dangerous when wet material 173.124 5 5.1 Oxidizer 173.127 5 5.2 Organic peroxide 173.128 6 6.1 Poisonous materials 173.132 6 6.2 Infectious substance (Etiologic agent) 173.134 7 Radioactive material 173.403 8 Corrosive material 173.136 9 Miscellaneous hazardous material 173.140 None Other regulated material: ORM-D 173.144

[Amdt. 173-224, 55 FR 52606, Dec. 21, 1990, as amended at 57 FR 45460, Oct. 1, 1992; Amdt. 173-234, 58 FR 51531, Oct. 1, 1993]