DeHaan, John. Spontaneous Ignition, Part I: What Really Happens. Fire
and Arson Investigator. Vol 46. No. 3. (March 1996). p 13-17.
Abstract: Spontaneous ignition can be defined as the onset of
burning when there is no external or ìpilotî source of ignition.
Since spontaneous combustion can be considered to be the ongoing process
of ignition throughout the mass of fuel, the ignition mechanism itself is
of the most critical interest to the fire investigator. If the conditions
are appropriate for spontaneous ignition to take place, once initiated,
it will develop into a growing combustion that can consume the entire fuel
mass. In solid fuels, the progression is from self-heating to smoldering
ignition of some or all of the fuel, followed in some cases by open flaming
combustion after some time delay. It is the flaming state that is most likely
to initiate a destructive fire. In premixed gas/air mixtures, ignition and
complete combustion are nearly simultaneous (i.e., very short time delay).
However, in solid materials the two events may be separated by minutes,
hours, or even weeks. Because the self-heating process is often so slow
as to be not readily observable, fire investigators are sometimes tempted
to regard spontaneous ignition as a myth that cannot happen. In addition
to considerable case documentation, there is also laboratory verification
of the processes and observed tests of spontaneous ignition. This paper
reviews the processes of self-heating and spontaneous ignition, describes
the thermodynamics of what is happening, and gives examples of the processes
involved; a second paper will discuss the investigation and documentation
of such cases.
For more information, contact:
International Association of Arson Investigators (IAAI)
300 Broadway Suite 100
St. Louis, MO 63102-2808