The Department of Transportation (DOT) has regulations under Title 49 CFR and before any type of material is transported it must have its hazards identified. Once identified it must be labeled onto the packaging and if it enters bulk packaging it will require placarding. Along with bulk packages, vehicles must also be placarded when transporting hazardous materials to warn people on the road of the potential hazards that are being transported.
There are 9 different classifications which are split between classes and divisions. Classes will have a single whole number, while a division will have a number with a decimal followed by another number.
Class 1 – Explosives
- Division 1.1 – Explosives which have a mass explosion hazard
- Examples: lead azide, TNT, silver fulminate
- Division 1.2 – Explosives which have a projection hazard but not have a mass explosion hazard
- Examples: mines with bursting charge, ammunition, grenades
- 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
- Examples: flash powder, rocket propellants
- Division 1.4 – Explosives which present no significant blast hazard
- Examples: fireworks, flares, tracers
- Division 1.5 – Very insensitive explosives with a mass explosion hazard
- Examples: blasting agents
- Division 1.6 – Extremely insensitive articles which do not have a mass explosion hazard
- Examples: restricted to military weapons and munitions
Class 2 – Gases
- Division 2.1 – Flammable gases
- Examples: acetylene, propane, dimethylamine (anhydrous), hydrogen
- Division 2.2 – Non-flammable gases
- Examples: carbon dioxide, helium, nitrogen, argon
- Division 2.3 -Toxic gases
- Examples: ammonia, methyl mercaptan, chlorine, phosphorus pentafluoride
Class 3 – Flammable Liquids
- Examples: ethanol, hexanes, methyl methacrylate
Class 4 – Flammable Solids, Substances liable to spontaneous combustion, Substances liable to spontaneous combustion
- Division 4.1 – Flammable solids, self-reactive substances and solid desensitized explosives
- Examples: magnesium, paraformaldehyde, sulfur, metal hydrides
- Division 4.2 – Substances liable to spontaneous combustion
- Examples: white phosphorus, titanium trichloride, tributyl phosphane, butyllithium
- Division 4.3 – Substances which in contact with water emit flammable gases
- Examples: potassium, cesium, lithium aluminum hydride, calcium carbide, aluminum phosphide
Class 5 – Oxidizing Substances and Organic Peroxides
- Division 5.1 – Oxidizing substances
- Examples: ammonium nitrate, bromine pentafluoride, ammonium perchlorate, sodium permanganate
- Division 5.2 – Organic peroxides
- Examples: benzoyl peroxide, tert-butyl hydroperoxide, methyl ethyl ketone peroxide
Class 6 – Toxic substances and Infectious Substances
- Division 6.1 – Toxic substances
- Examples: aniline, arsenic, mercuric chloride, pesticides
- Division 6.2 – Infectious substances
- Examples: Ebola, patient blood, regulated medical waste
Class 7 – Radioactive Materials
- Examples: americium-241, phosphorus-32, iodine-125, uranium, uranyl acetate
Class 8 Corrosive Substances
- Examples: antimony trichloride, nitric acid, stannic chloride, gallium, thionyl chloride
Class 9 Miscellaneous Dangerous Goods/Hazardous Materials and Articles
- Examples: lithium ion batteries, dry ice, asbestos
Sometimes a hazardous material can have two hazard classes and/or divisions. The primary hazard class and a subsidiary hazard class. This is indicated by the primary hazard class followed by the subsidiary hazard class in parentheses.
An example is boron trifluoride, CAS# 7637-07-2, it is a 2.3(8). So looking at the list, it is a toxic gas as its primary hazard and its subsidiary hazard is corrosive.
Depending on the chemical, some materials are forbidden from transport or forbidden if it is dry or not desensitized.
An example is lead azide, CAS# 13424-46-9, it has a hazard class of 1.1A, which means it is forbidden from transport unless it is wetted or in an alcohol-water mixture. This is due to lead azide’s extremely high shock and friction sensitivity.
If you’re curious about the DOT hazard classes for a chemical, you can refer to the DOT’s Hazardous Materials Table in 49 CFR Part 172.101 or go to any SDS for the chemical and look at Section 14: Transport Information.
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