UN/DOT Classification System for Hazardous Materials
Explosives—Class 1. The symbol is an exploding sphere on an orange background, and there are six subclasses:
- 1.1 Explosive with mass explosion hazard (detonation)
- 1.2 Explosive with projection hazard (detonation or deflagration)
- 1.3 Explosive with fire, minor blast or minor projection hazard
- 1.4 Explosive device with minor explosion hazard
- 1.5 Very insensitive explosives
- 1.6 Extremely insensitive explosives
Today placards, other than radioactive, do not contain the words designating the hazard class; they are referred to as "wordless placards."
Compressed Gas—Class 2. There are three subclasses: flammable gas, poison gas, or nonflammable nonpoisonous gas. The flammable gas placard is red with a flame symbol at the top. The nonflammable gas placard is green with a compressed gas cylinder symbol at the top. The poison gas placard is white with a skull and crossbones symbol at the top.
- 2.1 Flammable gas
- 2.2 Nonflammable gas
- 2.3 Poison gas
Flammable Liquid—Class 3. There are no subclasses in Class 3. Placards are red with a symbol of a flame at the top.
Flammable Solid—Class 4. Flammable solid, spontaneously combustible and dangerous when wet materials are included in this hazard class. The flammable solid placard has red and white vertical "candy" stripes with a flame at the top. The spontaneously combustible placard is white on the top half, and red on the bottom half, with a flame symbol at the top. The dangerous when wet placard is blue with a flame symbol at the top.
- 4.1 Flammable solid
- 4.2 Spontaneously combustible
- 4.3 Dangerous when wet
Oxidizer—Class 5. This class includes two subclasses: oxidizer and organic peroxide. These placards are yellow with the symbol of a flaming sphere at the top.
- 5.1 Oxidizer
- 5.2 Organic peroxide
Poison—Class 6. This class includes two subclasses: poison and infectious substance. The poison placard is white with a skull and crossbones at the top. There are also variations of this placard such as stowing away from foodstuffs, with a stalk of wheat with an "X" through it and a half placard with "Marine Pollutant" on it.
- 6.1 Poison
- 6.2 Infectious substance
Radioactive—Class 7. Placards in this class contain materials that carry the Radioactive III label. The placard is white on the top half and yellow on the bottom half. The radioactive propeller symbol is located at the top of the placard. The word "Radioactive" MUST appear on the placard. There are no subclasses.
Corrosive—Class 8. This class contains both acids and bases. The placard is white on the top half and black on the bottom half. The hand and metal corrosion symbol is at the top. There are no subclasses.
Miscellaneous Hazardous Materials—Class 9. This class contains materials not covered by other classes. The placard has black and white vertical stripes on the top half with a white bottom half. There is no wording on the placard. There are no subclasses.
Dangerous Placard. This placard indicates a mixed load of other hazard classes, excluding Table 1 materials. The placard has a red background with a white center portion with the word "Dangerous."