This testing makes my previous point. This scenario is not the same as dimensional lumber exposed to a constant temperature that allows the heat losses at the surface to be absorbed by an infinite heat sink with no measurable rise in the air temperature. This is the hypothesis that has been disproved at exposure temperature less than about 150 degree C.

I believe all of the previous incidents described involve some type of wood cavity. This is not an infinite heat sink and energy losses at the surface of the wood can be transfer to the air within the cavity and increase the exposure temperature with time. Not a constant exposure temperature as assumed in the current theory of the self-heating of wood.

In addition, assuming the end of the bolt is exposed in the cavity, it can also transfer thermal energy through convection and radiation to the air within the cavity. Do not confuse this scenario with the previous theory of the self-heating of wood exposed to a constant temperature.

An important note, 298 degree F is about 150 degrees C. Given the sensitivity of temperature in the theory of the self-heating of wood, 150 degrees C is a far cry from 77 or 100 degree C in terms of "low-temperature ignition of wood." The data in Bowes shows that 150 degrees C is well within the critical temperature cited for the self-heating of wood to thermal runaway. Depending on the critical dimensions, 150 degrees C is consistent with the theory of self-heating of wood without the need for any further inclusion of limitations on the hypothesis to include an insulated enclosure. Thus, these experiments, are reasonably consistent with the theory and do not disprove the hypothesis of the self-heating of wood to thermal runaway.

Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
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