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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Investigation => Topic started by: kurnal on June 09, 2007, 11:07:03 PM
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I think I remember reading of the spontaneous ignition of timber after repeated exposure to heat such as adjacent to sauna heaters and steam pipes in factories.
I think it was mentioned in either the IFE fire investigation handbook or chemistry and combustion but have mislaid my copies.
Before I recommend to an acquaintance that they buy these books, please could anyone confirm whether my memory is correct or whether there are any other sources of information on this topic? Cant seem to find anything relevant on google.
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There is a section in the booklet "A pocket guide to Arson and Fire Investigation" produced by the Fire Service College which talks about steam pipes.
It states "When heat is applied to cellulose materials (e.g. Wood), a pyrophoric action, which absorbs oxygen and leads to self heating, can occur. Also, wood in this condition will ignite at a lower tem[perature than normal."
My copy is dated 1994 so I don't know if there have been any updates or changes.
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Updated in 2001, Available from FM Global who produce it.
web is www.fmglobal.com If you are from a fire and rescue service they send it free
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This phenomenon has been given the name “pyrophoric carbon” by some and it is somewhat controversial, most of the discussion being in the USA.
Ignition of wood has been reported where hot water pipes penetrate timber members over a long period of time and the temperatures involved may be as low as 75°C. Some say that, because this has never been reproduced in the laboratory and there has never been a generally accepted theory, it does not exist.
Others point out that seeing it happen in the laboratory or the existence of an accepted theory is not a problem if there is a reasonable body of evidence that it has taken place – and there have been many such incidents reported. I subscribe to this view. There is a good treatment of the subject in Vyto Babrauskas’s Ignition Handbook.
The important thing to remember is that wood does not have a specific ignition temperature, ignition depends on temperature and the time that the temperature is maintained. It seems reasonable therefore that very long exposures may result in ignition at quite low temperatures.
One word of warning though, you should not put this forward as a source unless you have some pretty good evidence to support it.
Hope this is helpful.
Stan
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Most timbers are treated either with preservative, paint or stain etc. How much contributory factor of these giving off vapours which may be absorbed into the wood is there?
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Yes Stan,
The problem with lab tests is that they usually involve a fairly small number of tests under controlled conditions. Compared to the outside world where there are a vast number of tests being carried on over protracted periods under uncontrolled conditions.
I go with the Sherlock Holmes principal "Once you have eliminated the possible whatever is left must contain the answer"