Fire/Arson Investigations : Fire/Arson Investigations
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Re: My 2 cents for 921
Posted by: PMK140 (IP Logged)
Date: April 06, 2007 09:55AM
Doug,
I wrote: “Oddly enough, nearly all of these ‘Old Wives’ Tales’ have a basis in science." Bad choice of words. What I should have written was: “Oddly enough, nearly all of these ‘Old Wives’ Tales’ have SOME basis in science.”
1. “Negative Corpus” – “I have eliminated all other innocent fire causes; therefore all that is left is arson.” IF IN FACT ALL OTHER IGNITION SOURCES CAN BE ELIMINATED AN OPEN FLAME COULD BE REASONABLY INFERRED AS THE IGNITION SOURCE. HOWEVER, I BELIEVE THAT THE “INTENT” OF THE FIRE-SETTER, CAN SELDOM BE DIVINED FROM THE IGNITION SOURCE ALONE. IGNITION SOURCE AND FIRE CAUSE ARE CLEARLY NOT SYNONYMOUS.
2. The presence of a “For Sale” sign in front of the building is evidence of a possible motive for arson. (Read: Motive proves Arson). MOTIVE CAN ONLY BE USED TO HELP IDENTIFY AN ARSONIST ONCE AN INCENDIARY CAUSE HAS BEEN ESTABLISHED, BUT NEVER FOR THE DETERMINATION OF A FIRE CAUSE.
3. Burning on the floor is an indicator of an ignitable liquid fire (arson). BURNING ON THE FLOOR CAN BE CAUSED BY AN IGNITABLE LIQUID, BUT IS NOT THE ONLY SOURCE OF FLOOR BURNING.
4. Holes burned through the floor are indicative of liquid fuels (arson). HOLES BURNED IN THE FLOOR CAN BE CAUSED BY AN IGNITABLE LIQUID, BUT IGNITABLE LIQUIDS ARE NOT THE ONLY SOURCE OF SUCH HOLES.
5. Accelerated fires burn faster, hotter, at higher temperatures, (take your choice) than “normal” fires. ACCELERATED FIRES, PARTICULARLY THOSE FROM IGNITABLE LIQUIDS, DUE TEND TO BURN WITH HIGHER HEAT RELEASE RATES THAN CLASS “A” FIRES, BUT NOT NECESSARILY HIGHER TEMPERATURES.
6. Fires “seek” oxygen. FIRES BURN BETTER WHEN SUFFICIENTLY OXYGENATED AND IN AREAS NEAR SOURCES OF OXYGEN. THIS DOES NOT EQUATE WITH FIRE “SEEKING” ANYTHING. FIRES ARE INANIMATE RESULTS OF CHEMICAL AND PHYSICAL REACTIONS. THEY DO NOT “SEEK, NEITHER DO THEY “FIND.”
7. The presence of spalling on concrete means “Arson” (i.e. the use of an ignitable liquid). SPALLING OF CONCRETE CAN BE CAUSED BY THE PRESENCE OF IGNITABLE LIQUIDS, BUT IGNITABLE LIQUIDS ARE NOT EXCLUSIVE CAUSES OF SPALLED CONCRETE.
8. Wide “V’s” indicate slow fires; Narrow “V’s” mean fast fires. THE ANGLES OF THE LINES OF DEMARCATION OF A “V” PATTERN ARE GOVERNED BY MANY FACTORS NOT THE LEAST OF WHICH ARE CEILING HEIGHT, VENTILATION, MAXIMUM RATE OF HEAT RELEASE, AND TOTAL TIME OF BURNING. OTHER THAN IN SOME MODELING ISSUES THE TERMS “FAST FIRE” AND “SLOW FIRE” ARE NOT REALLY DEFINED IN FIRE INVESTIGATION PARTICULARLY WHEN DEFINING PLUME PATTERN SHAPE. RHETORICAL QUESTION: IN DEFINING A FLAME PLUME SHAPE, WHAT IS THE DIVIDING POINT BETWEEN A SLOW FIRE AND A FAST FIRE?
9. In an explosion, walls blown out from the bottom indicate heavier than air fuels [specific gravity (air), vapor density, greater than 1]: while walls blown out from the top indicate lighter than air fuels [specific gravity (air), vapor density, less than 1]. IN DIFFUSE FUEL EXPLOSIONS, THE ALTITUDE AT WHICH INDIVIDUAL WALLS DISASSOCIATE THEMSELVES FROM HORIZONTAL STRUCTURAL COMPONENTS IS AS MUCH OR EVEN MORE DEPENDANT ON THE NATURE OF CONSTRUCTION OR THE HEIGHT OF THE IGNITION SOURCE THAN THE VAPOR DENSITY OF THE FUEL/AIR MIXTURE.
10. Relative “expertise” can be judged by number of years of experience as a fire investigator. THE FACT THAT AN “OLD SCHOOL” INVESTIGATOR HAS BEEN DOING IT WRONG FOR A LONGER PERIOD OF TIME THAN ANOTHER IS NOT A CRITERION FOR EXPERTISE – QUITE THE CONTRARY.
On a personal note, I can't tell you how much I enjoy being publically quizzed by you on a statement that I thought was pretty self-evident. I must say that I am quite surprised that you don’t know this stuff and had to ask.
Pat Kennedy, CFEI, CFPS, MIFireE
Fire and Explosion Analyst
Sarasota, Florida
[www.kennedy-fire.com]
I wrote: “Oddly enough, nearly all of these ‘Old Wives’ Tales’ have a basis in science." Bad choice of words. What I should have written was: “Oddly enough, nearly all of these ‘Old Wives’ Tales’ have SOME basis in science.”
1. “Negative Corpus” – “I have eliminated all other innocent fire causes; therefore all that is left is arson.” IF IN FACT ALL OTHER IGNITION SOURCES CAN BE ELIMINATED AN OPEN FLAME COULD BE REASONABLY INFERRED AS THE IGNITION SOURCE. HOWEVER, I BELIEVE THAT THE “INTENT” OF THE FIRE-SETTER, CAN SELDOM BE DIVINED FROM THE IGNITION SOURCE ALONE. IGNITION SOURCE AND FIRE CAUSE ARE CLEARLY NOT SYNONYMOUS.
2. The presence of a “For Sale” sign in front of the building is evidence of a possible motive for arson. (Read: Motive proves Arson). MOTIVE CAN ONLY BE USED TO HELP IDENTIFY AN ARSONIST ONCE AN INCENDIARY CAUSE HAS BEEN ESTABLISHED, BUT NEVER FOR THE DETERMINATION OF A FIRE CAUSE.
3. Burning on the floor is an indicator of an ignitable liquid fire (arson). BURNING ON THE FLOOR CAN BE CAUSED BY AN IGNITABLE LIQUID, BUT IS NOT THE ONLY SOURCE OF FLOOR BURNING.
4. Holes burned through the floor are indicative of liquid fuels (arson). HOLES BURNED IN THE FLOOR CAN BE CAUSED BY AN IGNITABLE LIQUID, BUT IGNITABLE LIQUIDS ARE NOT THE ONLY SOURCE OF SUCH HOLES.
5. Accelerated fires burn faster, hotter, at higher temperatures, (take your choice) than “normal” fires. ACCELERATED FIRES, PARTICULARLY THOSE FROM IGNITABLE LIQUIDS, DUE TEND TO BURN WITH HIGHER HEAT RELEASE RATES THAN CLASS “A” FIRES, BUT NOT NECESSARILY HIGHER TEMPERATURES.
6. Fires “seek” oxygen. FIRES BURN BETTER WHEN SUFFICIENTLY OXYGENATED AND IN AREAS NEAR SOURCES OF OXYGEN. THIS DOES NOT EQUATE WITH FIRE “SEEKING” ANYTHING. FIRES ARE INANIMATE RESULTS OF CHEMICAL AND PHYSICAL REACTIONS. THEY DO NOT “SEEK, NEITHER DO THEY “FIND.”
7. The presence of spalling on concrete means “Arson” (i.e. the use of an ignitable liquid). SPALLING OF CONCRETE CAN BE CAUSED BY THE PRESENCE OF IGNITABLE LIQUIDS, BUT IGNITABLE LIQUIDS ARE NOT EXCLUSIVE CAUSES OF SPALLED CONCRETE.
8. Wide “V’s” indicate slow fires; Narrow “V’s” mean fast fires. THE ANGLES OF THE LINES OF DEMARCATION OF A “V” PATTERN ARE GOVERNED BY MANY FACTORS NOT THE LEAST OF WHICH ARE CEILING HEIGHT, VENTILATION, MAXIMUM RATE OF HEAT RELEASE, AND TOTAL TIME OF BURNING. OTHER THAN IN SOME MODELING ISSUES THE TERMS “FAST FIRE” AND “SLOW FIRE” ARE NOT REALLY DEFINED IN FIRE INVESTIGATION PARTICULARLY WHEN DEFINING PLUME PATTERN SHAPE. RHETORICAL QUESTION: IN DEFINING A FLAME PLUME SHAPE, WHAT IS THE DIVIDING POINT BETWEEN A SLOW FIRE AND A FAST FIRE?
9. In an explosion, walls blown out from the bottom indicate heavier than air fuels [specific gravity (air), vapor density, greater than 1]: while walls blown out from the top indicate lighter than air fuels [specific gravity (air), vapor density, less than 1]. IN DIFFUSE FUEL EXPLOSIONS, THE ALTITUDE AT WHICH INDIVIDUAL WALLS DISASSOCIATE THEMSELVES FROM HORIZONTAL STRUCTURAL COMPONENTS IS AS MUCH OR EVEN MORE DEPENDANT ON THE NATURE OF CONSTRUCTION OR THE HEIGHT OF THE IGNITION SOURCE THAN THE VAPOR DENSITY OF THE FUEL/AIR MIXTURE.
10. Relative “expertise” can be judged by number of years of experience as a fire investigator. THE FACT THAT AN “OLD SCHOOL” INVESTIGATOR HAS BEEN DOING IT WRONG FOR A LONGER PERIOD OF TIME THAN ANOTHER IS NOT A CRITERION FOR EXPERTISE – QUITE THE CONTRARY.
On a personal note, I can't tell you how much I enjoy being publically quizzed by you on a statement that I thought was pretty self-evident. I must say that I am quite surprised that you don’t know this stuff and had to ask.
Pat Kennedy, CFEI, CFPS, MIFireE
Fire and Explosion Analyst
Sarasota, Florida
[www.kennedy-fire.com]
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