spontaneous combustion

Spontaneous combustion or spontaneous ignition is a type of combustion which occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self heating which rapidly accelerates to high temperatures) and finally, autoignition. Cause and ignition Spontaneous combustion can occur when a substance with a relatively low ignition temperature (hay, straw, peat, etc.) begins to release heat. This may occur in several ways, either by oxidation in the presence of moisture and air, or bacterial fermentation, which generates heat. The heat is unable to escape (hay, straw, peat, etc. are good thermal insulators), and the temperature of the material rises above its ignition point (even though much of the bacteria are destroyed by ignition temperatures). Combustion begins if sufficient oxidizer, such as oxygen, and fuel are present to maintain the reaction into thermal runaway. Thermal runaway can occur when the amount of heat produced is greater than the rate at which the heat is lost, so materials that produce a lot of heat may combust in relatively small volumes, while materials that produce very little heat may only become dangerous when well insulated or stored in huge volumes. Most oxidation reactions accelerate at higher temperatures, so a pile of material that would have been safe at a low ambient temperature may spontaneously combust during hotter weather. Affected materials