The first Department of Transportation/United Nations (DOT/UN) hazard class deals with explosives. The DOT defines an


in 49 CFR 173.50 as “any substance or article, including a device, which is designed to function by explosion or which, by chemical reaction within itself, is able to function in a similar manner even if not designed to function by explosion.” This definition only applies to chemicals designed to create explosions. Another definition, taken from the

National Fire Academy Tactical Considerations Student Manual

, is “a substance or a mixture of substances, which, when subjected to heat, impact, friction, or other suitable initial impulse, undergoes a very rapid chemical transformation, forming other, more stable, products entirely or largely gaseous, whose combined volume is much greater than the original substance.”