DOT Hazard Classification System

The hazard class of dangerous goods/commodities is indicated either by its class (or division) number or name. Placards are used to identify the class or division of a material. The hazard class or division number must be displayed in the lower corner of a placard and is required for both primary and subsidiary hazard classes and divisions, if applicable.

First responders in the U.S. are trained to help identify a hazardous material during the first 15 minutes of an incident, based on the U.S. DOT/Pipeline and Hazardous Materials Safety Administration (PHMSA) Emergency Response Guidebook. The following is from Page 6.

Class 1 - Explosives

Division 1.1      Explosives which have a mass explosion hazard

Division 1.2      Explosives which have a projection hazard but not a mass explosion hazard

Division 1.3      Explosives which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard

Division 1.4      Explosives which present no significant blast hazard

Division 1.5      Very insensitive explosives with a mass explosion hazard

Division 1.6      Extremely insensitive articles which do not have a mass explosion hazard

Class 2 - Gasses

Division 2.1      Flammable gases

Division 2.2      Non-flammable, non-toxic* gases

Division 2.3      Toxic* gases

Class 3 - Flammable liquids (and Combustible liquids [U.S.])

Class 4 - Flammable solids; Substances liable to spontaneous combustion; Substances which, on contact with water, emit flammable gases

Division 4.1      Flammable solids, self-reactive substances and solid desensitized explosives

Division 4.2      Substances liable to spontaneous combustion

Division 4.3      Substances which in contact with water emit flammable gases

Class 5 - Oxidizing substances and Organic peroxides

Division 5.1      Oxidizing substances

Division 5.2      Organic peroxides

Class 6 - Toxic* substances and Infectious substances

Division 6.1      Toxic* substances

Division 6.2      Infectious substances

Class 7 - Radioactive materials

Class 8 - Corrosive substances

Class 9 - Miscellaneous dangerous goods/hazardous materials and articles

Download an expanded guide to the DOT Hazmat Classes

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*The words “poison” or “poisonous” are synonymous with the word “toxic”.[1]