Self-reactive substance

In the GHS, self-reactive substances and mixtures are a separate class. They are not the same as explosives, oxidizers or organic peroxides, though the classification criteria treat them similarly. Types are lettered from the most dangerous to the least, based on how the material behaves in testing.

The key fact is that the reaction feeds on the chemical itself. Warming can speed decomposition, and decomposition releases more heat. In a container that cannot vent, pressure and temperature can climb until the container ruptures. This is the same self-accelerating pattern seen with many organic peroxides.

Self-accelerating decomposition temperature is a figure often found in the supplier documentation. It describes the lowest temperature at which the packaged material can begin to decompose this way. Storage must stay below the stated limits, away from heat sources and direct sun, and some products need temperature-controlled storage.

Because the specific hazard varies from product to product, rely on the current SDS. Do not assume that similar-looking materials share the same limits, and do not repack them into other containers unless the supplier says it is acceptable.