John:

In your law article you state, “It is a never-proven hypothesis that on continued exposure to a heat source below its ignition temperature, the ignition of wood is lowered to a point where a heat source of only 200ºF might ignite it.”

Babrauskas cite a case in Canada where it was documented the temperature of the pipe passing through the wood was 170ºF. It is not known the length of time of this exposure, but it was known it was not a continuous exposure. I spoke directly with the investigator on this fire and he told me that he did determine the temperature of the water coming from the heater.

There was a paper published addressing the heating of wood inside of a wall in a commercial kitchen. There was a cheese melter of some type on the wall. There was no potential source of heat inside of the wall where the fire originated in three different restaurants. Independent testing found that the heat from the cheese melter and other cooking appliances in operation resulted in a wall temperature averaging 254ºF. In those same experiments the manufacturer of one of the units reported smoldering combustion within 30 minutes at 298ºF.

Jim Mazerat
Forensic Investigations Group