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: Fire Origin Pattern Persistence
Posted by: dcarpenter (IP Logged)
Date: October 31, 2016 07:51AM
I would put fourth that there are two thoughts on the use of fire patterns and origin determination.The first is the traditional thought that the analysis of fire patterns will yield the location of the area or volume of origin.
In general, there are some inherent problems with this methodology at the onset.
What if there is no adjacent surface to the fire origin for which the pattern can be produced on?
What if the adjacent surface to the fire origin for which the pattern can be produced on is consumed in a characteristic time frame much shorter than the time frame for post-flashover compartment fires? For example, cardboard boxes in center of the room or in high rack storage.
In the testing of this concept, one knows which pattern is the "origin pattern." How can someone identify that a pattern is the "origin pattern" of interest in compartment fires that are not part of testing? Fire patterns do not inherently have a time stamp that allows a historical record of when a fire pattern is produced. At best, one may be able to use fire dynamics to show the specific sequential order of the production of the fire patterns.
The second thought is that the patterns are data. This data can be used as evidence to test different origin hypotheses with respect to the growth and development of a fire using the Scientific Method. That is, can the patterns be produced as a result of the start of the fire at the hypothesized area of origin including the initial fuels and subsequent fuels distributed through out the area? This "test" of the origin hypothesis has always been part of the reliable application of the Scientific Method. This concept was expanded in NFPA 921 when the origin chapter was rewritten a few editions ago.
Given the current state of the combustion and fire sciences, reliable application can be had with the second method of use of fire patterns. Post-flashover compartment fires that burn for duration on the order the time frame for establishing a positive water supply and the onset of active fire suppression may not allow the "origin pattern" to "persist." A couple of minutes of post-flashover burning, as opposed to tens of minutes, may not be sufficient to reliably conclude that these patterns can persist.
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
In general, there are some inherent problems with this methodology at the onset.
What if there is no adjacent surface to the fire origin for which the pattern can be produced on?
What if the adjacent surface to the fire origin for which the pattern can be produced on is consumed in a characteristic time frame much shorter than the time frame for post-flashover compartment fires? For example, cardboard boxes in center of the room or in high rack storage.
In the testing of this concept, one knows which pattern is the "origin pattern." How can someone identify that a pattern is the "origin pattern" of interest in compartment fires that are not part of testing? Fire patterns do not inherently have a time stamp that allows a historical record of when a fire pattern is produced. At best, one may be able to use fire dynamics to show the specific sequential order of the production of the fire patterns.
The second thought is that the patterns are data. This data can be used as evidence to test different origin hypotheses with respect to the growth and development of a fire using the Scientific Method. That is, can the patterns be produced as a result of the start of the fire at the hypothesized area of origin including the initial fuels and subsequent fuels distributed through out the area? This "test" of the origin hypothesis has always been part of the reliable application of the Scientific Method. This concept was expanded in NFPA 921 when the origin chapter was rewritten a few editions ago.
Given the current state of the combustion and fire sciences, reliable application can be had with the second method of use of fire patterns. Post-flashover compartment fires that burn for duration on the order the time frame for establishing a positive water supply and the onset of active fire suppression may not allow the "origin pattern" to "persist." A couple of minutes of post-flashover burning, as opposed to tens of minutes, may not be sufficient to reliably conclude that these patterns can persist.
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.