Fire/Arson Investigations : Fire/Arson Investigations
A place to ask questions and add to probative and informative discussions associated with the various aspects of the field of fire investigation. -- FORUM RULES---BE CIVIL AND NO NAME CALLING, NO BELITTLING, NO BERATING, NO DENIGRATING others. Postings in violation of these rules can be removed or editted to remove the offending remarks at the discretion of the moderators and/or site administrator.
Re: Ignition temperature of wood
Posted by: dcarpenter (IP Logged)
Date: September 28, 2020 12:36PM
This hypothesis has been tested. Wood was exposed to long-term heating and then tested for its ignition properties. The work disproved this hypothesis.
While there is evidence that self-heating to thermal runaway for dimensional lumber for exposure temperatures of around 200 degrees C, I have not seen any evidence produced by trying to reproduce self-heating to thermal runaway in any testing at much lower temperatures.
It is my hypothesis that there are conditions associated with this phenomenon that are not being accounted for in the testing. The enclosure of dimensional lumber may provide a means to increase the exposing temperature with time. Instead of self-heating of the dimensional lumber, there may be self-heating of the entire enclosure. When looking at the self-heating to thermal runaway theory, the control volume for the energy balance may not be on the surface of a single piece of dimensional lumber. Rather the control volume is on the outside of the enclosure and would account for any heating of the air that is exposing the wood to a higher temperature with time. This hypothesis needs to be tested.
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)
www.csefire.com
While there is evidence that self-heating to thermal runaway for dimensional lumber for exposure temperatures of around 200 degrees C, I have not seen any evidence produced by trying to reproduce self-heating to thermal runaway in any testing at much lower temperatures.
It is my hypothesis that there are conditions associated with this phenomenon that are not being accounted for in the testing. The enclosure of dimensional lumber may provide a means to increase the exposing temperature with time. Instead of self-heating of the dimensional lumber, there may be self-heating of the entire enclosure. When looking at the self-heating to thermal runaway theory, the control volume for the energy balance may not be on the surface of a single piece of dimensional lumber. Rather the control volume is on the outside of the enclosure and would account for any heating of the air that is exposing the wood to a higher temperature with time. This hypothesis needs to be tested.
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)
www.csefire.com
Sorry, only registered users may post in this forum.