Basics of Fire Cause Investigation Flashcards
What are the 3 reasons why we investigate fires?
It is the law required by international fire code
To determine the unsafe products/procedures that may be causing/creating a danger to the community
To determine incendiary fires and investigate until the responsible party/s have been brought to prosecution
What is the definition of fire?
The rapid, self sustaining oxidation process usually accompanied by the evolution of heat and light in varying intensities
What is the fire tetrahedron?
O2
Fuel
Heat
Uninhibited chain reaction
What are the 3 methods of heat transfer on the power point?
Conduction
Convection
Radiation
What is conduction?
Heat transfer by direct contact of one body to another
What is convection?
Heat transfer by circulating medium
Can be gas or liquid
What form of heat transfer is most responsible for the spread of heat in structural fires?
Convection
What is radiation?
Heat transfer from one area to another without direct contact with the area and without any circulating hot gases to help “bathe” the area in heat
It’s in the form of energy which travels through space or materials as waves
What is flashover?
Contained fire where exposed surfaces simultaneously ignite from thermal radiation
Stage of fire when room or other area becomes heated to the point when flames flash over the entire area
What is backdraft?
An explosion or rapid burning of heated gases resulting from the introduction of O2 when air is admitted into a building heavily charged by smoke from a fire that has depleted O2 content of the building
What is the temperature range for the growth/incipient stage? O2 content?
300-600
21%
What is the temperature range for the free burning stage? O2 content?
1200-2000
18%
What is the temperature range for the smoldering stage? O2 content?
800-1000
13-15%
What are the 4 combustion by products listed on the powerpoint?
Fire gases
Heat
Flame
Smoke
What is the “point of origin”?
The place of the fire’s beginning
Normally, the fire cause will be found at…
At or very near the point of origin
Fires often burn ____ near the point of origin
Longer
Evidence of _____ is often recovered near the point of origin.
Incendiarism
Evidence of fire spread/direction of fire travel may be noted/confirmed after locating the ____ __ ___.
Point of origin
The point of origin may ___ or ____ the stories of owners/occupants/suspects
Confirm or contradict
Investigators must usually work ____ in relation to the fire’s travel or spread, working toward the point of origin.
Backwards
Fire cause investigation is commonly referred to as a ____ investigation
Backward
With fire cause investigation… what 2 things are you looking at on the exterior of the structure?
Note areas damaged by heat and smoke
Fire damage to building exterior
(Isn’t that the same thing? Whatever…)
Ceiling damage and floor damage may help to locate the ___ __ ___
Point of origin
What might the lack of soot (carbon) in a heavily burned area indicate?
The area of origin
You can look at structural damage from fire as an indicator of…
Fire’s travel
The depth of charring can be an indicator of travel and the point of origin.
Fire penetrates into wood 1” every ___ minutes at approx ____ degrees F
45 minutes
1400
What does light staining on glass objects indicate?
Limited fire or intense heat and/or rapid fire growth
What does heavy staining on glass objects indicate?
Slow fire build up or remote distance from point of origin
What is the exception with heavy staining on glass objects?
Heavy petroleum based fire load
What is the melting temp of aluminum?
1200F
What is the melting temp of copper?
2000F
What is the melting temp of window glass?
900F when exposed for 10 minutes
On the interior of a structure, ____ is necessary to properly determine the point of origin
Reconstruction
What are the 2 things listed on the power point under “reconstruction”?
Locating the proper position of items within the fire scene
Identification and use of “protected areas”
Reconstruction allows the investigator to do what 3 things?
Determine the lowest level of burning
Determine V patterns
Evaluate the fuel load and burning sequence within an area
What are the “three elements of fire” on the fire cause poiwer point?
Heat source
Fuel
An event which brings together the heat source and the fuel