Fire
Produced when a substance undergoes rapid oxidation involving heat and light.
Fire Triangle
Shows the three elements needed to produce and sustain a fire.
Flash point
The lowest temperature to which a substance must be heated in order for the substance to give off vapors which will burn when exposed to a flame or ignition source.
Point of Origin
The location where the fire started.
Burn patterns
-Noticeable patterns created by the fire as it burns.
Accelerants
Substances, such as gasoline, paint thinner, and alcohol, that accelerate the burning process
Arson
A fire started deliberately.
fire triangle
represents the three elements needed for fire to occur: heat, fuel, and oxygen
heat
is the energy necessary to increase the temperature of the fuel to a point where sufficient vapors are given off for ignition to occur.
fuel
can be any combustible material in any state of matter - solid, liquid, or gas. Most solids and liquids become a vapor or gas before they will burn.
Fire requires an atmosphere with at least 16% oxygen
16% oxygen
The air we breathe is about
21% oxygen.
Char Patterns
Created by very hot fires that burn very quickly and move fast along its path, so that there can be sharp lines between what is burned and what isn't.
Point of Origin
Burn patterns and other damage can help determine the point of origin, or the location where the fire started.
A char pattern on a door would help an investigator determine
which side of the door the fire was on.
A char pattern on the floor would help investigators determine
the use of an accelerant and its path.
V-Patterns
Fire burns up, in a V-shaped pattern, so a fire that starts at an outlet against a wall leaves a char pattern that points to the origin.
A very narrow V-shape might indicate a fire that was
hotter than normal, such as one helped along by an accelerant.
A wide V-shape might indicate a fire that was
slow burning
A U-shape could indicate that there was a
pool of origin" rather than a point of origin, such as might be caused by, say, a puddle of gasoline.
Heat Shadows
Occur when heavy furniture shields part of a wall; can help determine the origin point.
Light bulbs tend to melt toward
the heat source, so the "direction of melt" can indicate the direction of the fire.
Glass
Glass fragments, windows, and light bulbs can provide clues to a fire.
The shattered or cracked glass of the windows can provide indications as to
how a fire burned.
Chimney Effect
where the fire ignites at a point, the superheated gases rise upward and form a fireball, which continues straight up to burn a hole in the ceiling. If the roof is not entirely burnt, and the fire investigator finds such a hole, the origin of the fire cou
Color of smoke
Determine what type material was burning
Color of flames
Indicates at what temperature the fire was burning.
Crime concealment
To conceal another crime such as murder, burglary, or vehicle.
Revenge or spite
To get back at someone for a perceived injustice
Monetary Gain
Arson-for-Profit fires are set to burn a building, vehicle, or some other object in order to gain profit from the fire. The profit may come in several forms; from insurance coverage on the property, or from putting a competitor out of business.
Malicious Vandalism
Fire set to someone's property, just to destroy it. Malicious vandalism fires account for the largest percentage of arson fires. These fires are frequently set by juveniles.
Mentally Disturbed
Some persons have been found to have an irresistible impulse to set fires.