Fire investigation involves the examination of all fire-related incidents once firefighters have extinguished the fire. The practice is similar to the examination of crime scenes in that the scene must be preserved and evidence collected and analysed, but with numerous additional difficulties and dangers. The investigation will include closely surveying the damaged scene to establish the origin of the fire and eventually establishing the cause.
However in order to effectively examine and evaluate a fire scene, it is imperative that the investigator has a detailed knowledge of the chemistry and behaviour of fire and its effects.
Nature & Chemistry of Fire Fire occurs due to the exothermic reaction of combustion (burning), producing heat and light. In order for a fire to occur, three vital components must be present: a fuel source, an oxidant (often O2) and a sufficient amount of energy in the form of heat. Together these make up the fire triangle. More recently a fourth factor has been described – a self-sustaining chemical chain reaction – to produce the fire tetrahedron. The absence of any of these conditions will result in a fire not starting or extinguishing through smothering (oxygen removal), cooling (heat removal) or starving (fuel removal).