UN number

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UN numbers or UN IDs are four-digit numbers that identify hazardous substances, and articles (such as explosives, flammable liquids, toxic substances, etc.) in the framework of international transport. Some hazardous substances have their own UN numbers (e.g. acrylamide has UN2074), while sometimes groups of chemicals or products with similar properties receive a common UN number (e.g. flammable liquids, not otherwise specified, have UN1993). A chemical in its solid state may receive a different UN number than the liquid phase if their hazardous properties differ significantly; substances with different levels of purity (or concentration in solution) may also receive different UN numbers.

UN numbers range from UN0001 to about UN3506 and are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods. They are published as part of their Recommendations on the Transport of Dangerous Goods, also known as the Orange Book. These recommendations are adopted by the regulatory organization responsible for the different modes of transport.

There is no UN number allocated to non-hazardous substances. These will simply not have a UN number.

For more details, see List of UN Numbers.

NA numbers (North America), also known as DOT numbers are issued by the United States Department of Transportation and are identical to UN numbers, except that some substances without a UN number may have an NA number. These additional NA numbers use the range NA8000 - NA9999.

Hazard identifiers[edit]

Associated with each UN number is a hazard identifier, which encodes the general hazard class and subdivision (and, in the case of explosives, their compatibility group). If a substance poses several dangers, then subsidiary risk identifiers may be specified. It is not possible to deduce the hazard class(es) of a substance from its UN number: they have to be looked up in a table.

UN hazard identifiers
class division description
Class 1 Explosives
Division 1.1 Explosives with a mass explosion hazard
Division 1.2 Explosives with a projection hazard
Division 1.3 Explosives with predominantly a fire hazard
Division 1.4 Explosives with no significant blast hazard
Division 1.5 Very intensive explosives with a mass explosion hazard
Division 1.6 Extremely insensitive articles
Class 2 Gases
Division 2.1 Flammable gases
Division 2.2 Non-flammable, non-toxic (non-poisonous) gases
Division 2.3 Toxic (poisonous) gases
Class 3 Flammable liquids (and Combustible liquids [U.S.])
Class 4 Flammable solids; Spontaneously combustible materials; and Dangerous when wet materials/Water-reactive substances
Division 4.1 Flammable solids
Division 4.2 Spontaneously combustible materials
Division 4.3 Water-reactive substances/Dangerous when wet materials
Class 5 Oxidizing substances and Organic peroxides
Division 5.1 Oxidizing substances
Division 5.2 Organic peroxides
Class 6 Toxic (poisonous) substances and Infectious substances
Division 6.1 Toxic (poisonous) substances
Division 6.2 Infections substances
Class 7 Radioactive materials
Class 8 Corrosive substances
Class 9 Miscellaneous hazardous materials/Products, Substances, or Organisms

See also[edit]

External links[edit]