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 UN3518 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 Lists 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.

Class 1: Explosives
Information on this graphic changes depending on which, "Division" of explosive is shipped. Explosive Dangerous Goods have compatibility group letters assigned to facilitate segregation during transport. The letters used range from A to S excluding the letters I, M, O, P, Q and R. The example above shows an explosive with a compatibility group "A" (shown as 1.1A). The actual letter shown would depend on the specific properties of the substance being transported.

For example, the Canadian Transportation of Dangerous Goods Regulations provides a description of compatibility groups.

  • 1.1 Explosives with a mass explosion hazard
  • 1.2 Explosives with a severe projection hazard.
  • 1.3 Explosives with a fire, blast or projection hazard but not a mass explosion hazard.
  • 1.4 Minor fire or projection hazard (includes ammunition and most consumer fireworks).
  • 1.5 An insensitive substance with a mass explosion hazard (explosion similar to 1.1)
  • 1.6 Extremely insensitive articles.

The United States Department of Transportation (DOT) regulates hazmat transportation within the territory of the US.

1.1 — Explosives with a mass explosion hazard. (nitroglycerin/dynamite)
1.2 — Explosives with a blast/projection hazard.
1.3 — Explosives with a minor blast hazard. (rocket propellant, display fireworks)
1.4 — Explosives with a major fire hazard. (consumer fireworks, ammunition)
1.5 — Blasting agents.
1.6 — Extremely insensitive explosives.
Class 1: Explosives Hazardous Materials
Class 1: Explosives
Class 1.1: Explosives Hazardous Materials
Class 1.1: Explosives

Mass Explosion Hazard
Class 1.2: Explosives Hazardous Materials
Class 1.2: Explosives

Blast/Projection Hazard
Class 1.3: Explosives Hazardous Materials
Class 1.3: Explosives

Minor Blast Hazard
Class 1.4: Explosives Hazardous Materials
Class 1.4: Explosives

Major Fire Hazard
Class 1.5: Blasting Agents Hazardous Materials
Class 1.5: Blasting Agents

Blasting Agents
Class 1.6: Explosives Hazardous Materials
Class 1.6: Explosives

Extremely Insensitive Explosives
Class 2: Gases
Gases which are compressed, liquefied or dissolved under pressure as detailed below. Some gases have subsidiary risk classes; poisonous or corrosive.
  • 2.1 Flammable Gas: Gases which ignite on contact with an ignition source, such as acetylene, hydrogen, and propane.
  • 2.2 Non-Flammable Gases: Gases which are neither flammable nor poisonous. Includes the cryogenic gases/liquids (temperatures of below -100 °C) used for cryopreservation and rocket fuels, such as nitrogen, neon, and carbon dioxide.
  • 2.3 Poisonous Gases: Gases liable to cause death or serious injury to human health if inhaled; examples are fluorine, chlorine, and hydrogen cyanide.
Class 2.1: Flammable Gas Hazardous Materials
Class 2.1: Flammable Gas
Class 2.2: Nonflammable Gas Hazardous Materials
Class 2.2: Nonflammable Gas
Class 2.3: Poisonous Gas Hazardous Materials
Class 2.3: Poisonous Gas
Class 2.2: Oxygen (Alternative Placard) Hazardous Materials
Class 2.2: Oxygen (Alternative Placard)
Class 2.3: Inhalation Hazard (Alternative Placard) Hazardous Materials
Class 2.3: Inhalation Hazard (Alternative Placard)
Class 3: Flammable Liquids
Flammable liquids included in Class 3 are included in one of the following packing groups:
  • Packing Group I, if they have an initial boiling point of 35°C or less at an absolute pressure of 101.3 kPa and any flash point, such as diethyl ether or carbon disulfide;
  • Packing Group II, if they have an initial boiling point greater than 35°C at an absolute pressure of 101.3 kPa and a flash point less than 23°C, such as gasoline (petrol) and acetone; or
  • Packing Group III, if the criteria for inclusion in Packing Group I or II are not met, such as kerosene and diesel.

Note: For further details, check the Dangerous Goods Transportation Regulations of the country of interest.

Class 3: Flammable Liquids Hazardous Materials
Class 3: Flammable Liquids
Class 3: Combustible (Alternate Placard) Hazardous Materials
Class 3: Combustible (Alternate Placard)
Class 3: Fuel Oil (Alternate Placard) Hazardous Materials
Class 3: Fuel Oil (Alternate Placard)
Class 3: Gasoline (Alternate Placard) Hazardous Materials
Class 3: Gasoline (Alternate Placard)
Class 4: Flammable Solids
Class 4.1: Flammable Solids Hazardous Materials
Class 4.1: Flammable Solids

4.1 Flammable Solids: Solid substances that are easily ignited and readily combustible (nitrocellulose, magnesium, safety or strike-anywhere matches).
Class 4.2: Spontaneously Combustible Solids Hazardous Materials
Class 4.2: Spontaneously Combustible Solids

4.2 Spontaneously Combustible: Solid substances that ignite spontaneously (aluminium alkyls, white phosphorus).
Class 4.3: Dangerous when Wet Hazardous Materials
Class 4.3: Dangerous when Wet

4.3 Dangerous when Wet: Solid substances that emit a flammable gas when wet or react violently with water (sodium, calcium, potassium, calcium carbide).
Class 5: Oxidizing Agents and Organic Peroxides
Class 5.1: Oxidizing Agent Hazardous Materials
Class 5.1: Oxidizing Agent

5.1 Oxidizing agents other than organic peroxides (calcium hypochlorite, ammonium nitrate, hydrogen peroxide, potassium permanganate).
Class 5.2: Organic Peroxide Oxidizing Agent Hazardous Materials
Class 5.2: Organic Peroxide Oxidizing Agent

5.2 Organic peroxides, either in liquid or solid form (benzoyl peroxides, cumene hydroperoxide).
Class 6: Toxic and Infectious Substances
Class 6.1: Poison Hazardous Materials
Class 6.1: Poison
  • 6.1a Toxic substances which are liable to cause death or serious injury to human health if inhaled, swallowed or by skin absorption (potassium cyanide, mercuric chloride).
  • 6.1b (Now PGIII) Toxic substances which are harmful to human health (N.B this symbol is no longer authorized by the United Nations) (pesticides, methylene chloride).
Class 6.2: Biohazard Hazardous Materials
Class 6.2: Biohazard
  • 6.2 Biohazardous substances; the World Health Organization (WHO) divides this class into two categories: Category A: Infectious; and Category B: Samples (virus cultures, pathology specimens, used intravenous needles).
Class 7: Radioactive substances Class 8: Corrosive substances Class 9: Miscellaneous
Class 7: Radioactive Hazardous Materials
Class 7: Radioactive

Radioactive substances comprise substances or a combination of substances which emit ionizing radiation (uranium, plutonium).
Class 8: Corrosive Hazardous Materials
Class 8: Corrosive

Corrosive substances are substances that can dissolve organic tissue or severely corrode certain metals:
Class 9: Miscellaneous Hazardous Materials
Class 9: Miscellaneous

Hazardous substances that do not fall into the other categories (asbestos, air-bag inflators, self inflating life rafts, dry ice).

See also[edit]

External links[edit]