An assessment of hot metal fragments from heavy mechanical equipment as a potential ignition source for forest litter

Abstract

The presence of metal particles, produced by rock strikes with heavy mechanical equipment, has come to be considered as evidence of fire causation in the investigation of forest fires. I report here the results of a series of experiments where direct thermographic measurements were made of the temperatures of the fragments that are created by repeatedly driving a bulldozer over rocks under extreme conditions. It is apparent, from these experimental determinations, a theoretical evaluation of the process that gives rise to them and comparison with published data, including the ignition of cellulose fuel beds by steel particles, that the minimum requirements for the ignition of kindling are not being met and that such fragments are not in fact a viable source of ignition for forest litter.