HazMat Segregation and Incompatible Materials
Certain HazMat classes must be separated from each other in transport to prevent catastrophic chemical reactions if a release occurs. The segregation rules are codified in 49 CFR 177.848 (segregation table). Key incompatible combinations: Explosives (Division 1.1, 1.2) cannot be loaded with: other Class 1 explosives (except under specific conditions), flammable liquids, corrosives, oxidizers, or poisons. The risk is initiation of an explosive detonation chain. Poisons (Division 6.1 and Division 2.3) cannot be loaded with: food, feed, or other edible substances — contamination risk even through package failure. Oxidizers (Class 5.1) must be separated from flammable liquids, flammable solids, and organic peroxides — oxidizer contact with flammable material dramatically accelerates combustion. Chlorine (and other Division 2.3 poison gases) cannot be loaded with anhydrous ammonia (also a toxic gas). The mixing products are extremely hazardous. The segregation table uses four categories: Stow Away From (no specific distance, but in different areas of the vehicle), Separated By (specific distance between packages), Separated From (different compartments or separated by bulk quantity), and May Not Be Co-Loaded (absolute prohibition). Drivers have the right and responsibility to refuse co-loading prohibited material combinations.