The Combustion Process
What makes a fire burn? Why is one fire a roaring inferno while another barely creeps along? Fire is a chemical reaction in which energy in the form of heat is produced. When forest fuels burn, there is a chemical combination of the oxygen in the air with woody material, pitch and other burnable elements found in the forest environment. This process in known as �Combustion.� Combustion is a chain reaction chemically similar to photosynthesis in reverse.
Photosynthesis requires a large amount of heat which is furnished by the sun. The Combustion process releases this heat. The tremendous amount of heat that is produced in the burning process is the major reason that the suppression of wildfires is such a difficult task and why the use of prescribed fire is a complex and exacting process requiring knowledgeable and experienced people.
The combustion process or �fire� is sometimes called �rapid oxidation.� It is similar to the formation of rust on iron or the decay of dead wood in the forest, except that the process is drastically speeded up.
Fire begins with ignition. The match is a common ignition device. Friction creates sufficient heat to ignite the phosphorus on the end of the match. Combustion occurs and the match flames.
Heat is necessary to begin the combustion process. Once started, fire produces its own heat. Wild land fires originate from such sources of heat as matches, embers from cigarettes, cigars or pipes, campfires, trash fires, exhaust sparks from railroad locomotives, sparks from brake shoes or �hot-box� on railroad cars. lightning, spontaneous combustion, hot ashes and arson.