The following are some terms used to define and describe fire activity.
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Fire Behavior Terms & Definitions
Boiling Point
The temperature of a substance where the rate of evaporation exceeds the rate of condensation.
British Thermal Unit (BTU)
The amount of heat needed to raise the temperature of one pound of water one degree F.
Calorie
The amount of heat needed to raise the temperature of one gram of water one degree Centigrade.
Centigrade (Celsius)
On the Centigrade scale, zero is the melting point of ice; 100 degrees is the boiling point of water.
Endothermic Heat Reaction
A chemical reaction where a substance absorbs heat energy.
Exothermic Heat Reaction
A chemical reaction where a substance gives off heat energy.
Fahrenheit
On the Fahrenheit scale, 32 degrees is the melting point of ice; 212 degrees is the boiling point of water.
Fire Point
The temperature at which a liquid fuel will produce vapors sufficient to support combustion once ignited. The fire point is usually a few degrees above the flash point.
Flammable or Explosive Limits
The percentage of a substance in air that will burn once it is ignited. Most substances have an upper (too rich) and a lower (too lean) flammable limit.
Flash Point
The minimum temperature at which a liquid fuel gives off sufficient vapors to form an ignitable mixture with the air near the surface. At this temperature, the ignited vapors will flash, but will not continue to burn.
Heat
The form of energy that raises temperature. Heat is measured by the amount of work it does.
Ignition Temperature
The minimum temperature to which a fuel in air must be heated in order to start self-sustained combustion independent of the heating source.
Oxidation
The complex chemical reaction of organic material with oxygen or other oxidizing agents in the formation of more stable compounds.
Source: Adapted from LBFD Training Division documentation.
