ISI Investigations
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ACCELERANT
In chemistry, a catalyst (a compound that may speed up a chemical process). In fire investigation, the term is used to describe liquids and compounds utilized by arsonists in the setting of fires, such as alcohol, gasoline, charcoal lighter fluid, and paint thinner.
ACETYLENE
A colorless hydrocarbon gas, C 2 and H 2, that is produced by the action of water upon certain carbon compounds and used principally in welding and cutting operations.
ALERT
The action the canine makes to indicate to the handler that an accelerant has been located.
ALERT POINT
The point where a canine indicates that an accelerant is located.
ALLIGATORING
Describes visual patterns showing the degree of the carbonizing process of wood when exposed to flame or sufficient heat. This results in structural deterioration of the wood, characterized by cracks and ridges resembling the back of an alligator.
AMPERAGE
The strength of a current measured in amps.
AMPERE (AMP)
A unit of rate of flow of electricity. Flow of electricity depends upon the pressure in volts and resistance, identified as impedance, in alternating current circuits.
ANNEAL
Removal of tension from spring steel through the application of heat. An example would be coil springs that have collapsed within themselves and will not spring back after being exposed to heat and fire.
ARC/ARCING
Either intentionally (by a switch), or accidentally (because of a loosened terminal), heating that results from high resistance when an electric current is interrupted. The degree of heat or intensity of the arc depends upon the amount of current in the circuit. Electric arcs can ignite combustibles because of sparks being thrown in the general vicinity of the fault, whereas fault type heating alone, in an overloaded conductor, may result in the ignition of insulation and of combustibles in the immediate proximity of the conductor. Either of the above conditions can result without opening the circuit breaker or other circuit safety device.
AREA OF ORIGIN
The term used by fire investigators to describe the general area where a fire started. It is not limited to the specific point of origin. The term may describe an entire building in a multibuilding fire or a room in a structure.
ARSON
To willfully and maliciously burn or cause to be burned, or aid, counsel or procure the burning of any structure, forest land or property. Does not include a person burning own property unless there is intent to defraud or there is injury to another person or damage to another person's property.
AUTO-IGNITION TEMPERATURE
The minimum temperature to which material must be heated to initiate or create self sustained combustion, independent of any outside heat source. The term is also used in the discussion of spontaneous heating resulting from physical, chemical, and biological reactions.
BEADING
A condition found on electrical wiring when arcing has occurred. The electrical wire ends appear beaded or formed into a series of melted round balls.
BRITISH THERMAL UNIT (BTU)
The amount of heat necessary to raise the temperature of one pound of water one degree Fahrenheit (F), measured at 60 degrees F. One BTU equals 252 calories. It is important to recognize the difference between heat and temperature. Heat is quantity of measurement whereas temperature is the measure of intensity. Specific heat or thermal capacity of a substance is the number of BTUs required to raise the temperature of one pound of the substance one degree F or the number of calories to raise one gram of the substance through one degree Centigrade.
BURNING POINT
The temperature which a substance must attain before it will ignite on the application of an ignition source or a flame. Pre-heated materials ignite more quickly when a flame is introduced because it may have already reached the burning point.
BURN PATTERN
Used in defining and illustrating the progress of a fire by means of visible charring, decomposition, and displacement. It may be used to define carbonization from luminous and non-luminous combustion, spontaneous ignition process, and pyrolysis. It may be used in describing major fire progress or limited progress inside walls or isolated areas and spaces. When used by experts, they should be required to define the concept behind its use.
BUSS FUSE
Device used for overcurrent protection. May also be called plug fuse.
To download a PDF version of the Glossary of Fire Investigation Terms click here.
