Class A Explosives. Possessing detonating hazard, such as dynamite, nitroglycerin, picric acid, lead azide, fulminate of mercury, black powder, blasting caps, and detonating primers.
Class B Explosives. Possessing flammable hazard, such as propellant explosives, including some smokeless propellants.
Class C Explosives. Include certain types of manufactured articles which contain Class A or Class B explosives, or both, as components, but in restricted quantities.
29 C.F.R. §1926.914