Fire Behavior and Combustion

Topics: Thermodynamics, Heat, Energy Pages: 5 (998 words) Published: July 23, 2013
Unit 1 Assignment: Critical Terms Study Guide

FS101: Fire Behavior and Combustion

Unit 1

Unit 1 Assignment: Critical Terms Study Guide

Auto-ignition temperature The minimum temperature to which a material must be raised before combustion will occur. Also called “ignition temperature.”

Backdraft A sudden, violent reignition of the contents of a closed container fire that has consumed the oxygen within the space when a new source of oxygen is introduced. The introduction of oxygen results in an immediate smoke explosion.

Boiling point (BP) The temperature where a liquid will convert to a gas at a vapor pressure equal to or greater than atmospheric pressure.

British thermal unit (BTU) The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.

Class A fires Fires involving ordinary combustibles.

Class B fires Fires involving flammable liquids.

Class C fires Fires involving energized electrical equipment or wires.

Class D fires Fires involving combustible metals.

Class K fires Fires involving cooking oils.

Combustion A chemical process between fuel and oxygen with the evolution of light either as a glow or flame and heat. Some of the heat energy is radiated back into the fuel, releasing more fuel to allow the combustion process to continue.

Conduction The transfer of heat energy by the movement of the heat-agitated atoms colliding with each other, transmitting some of the energy or heat.

Convection The movement of heat energy by the agitation of air molecules reduces the density of molecules making heated air lighter than cooled air. In a heated enclosed compartment, the heated air rises and pulls in cooled air below the flaming level.

Decay stage (burnout phase) The stage at which fire has consumed all the available fuel, and the temperature begins to decrease as the fire reduces in intensity.

Endothermic The type of reaction in which energy is absorbed when the reaction takes place.

Evaporation The process of air moving over the surface of water while picking up water vapor. Water vapor is simply water in a gaseous state, and is an important ingredient in fire behavior.

Exothermic The type of reaction that will release or give off energy.

Explosive range The range of concentrations of the gases or materials (dusts) in the air, which will permit the material to burn.

Fire A rapid, self-sustaining oxidation process that involves heat, light, and smoke in varying quantities. It is often an unplanned or uncontrolled event, as in most cases the fuels are not selected or even known in advance. See also combustion.

Fire point The lowest temperature at which a liquid produces a vapor that can sustain a continuous flame.

Fire tetrahedron A four-sided model describing the heat, fuel, oxygen, and chemical reaction necessary for combustion.

Fire triangle An older three-sided model used to describe the heat, fuel, and oxygen necessary for fire. This model is now revised with the introduction of the fire tetrahedron model.

Firing out

Flame over (rollover) The flames that travel through or across unburned gases in the upper portions of the confined area during the fire’s development.

Flammable range The numerical difference between a flammable substance’s lower and upper explosive limits in air.

Flashover fire A sudden event that occurs when all of the contents of a room or enclosed compartment reach their ignition temperature almost simultaneously, producing an explosive fire.

Flash point The lowest temperature at which a liquid produces a vapor that can sustain a continuous flame.

Growth stage Where the fire increases its fuel consumption and heat generation.

Heat Heat may be defined as energy in transit from a high temperature object to a lower temperature object. 

Heat Flux Heat flux or thermal flux is the rate of heat energy transfer through a given surface . The SI derived unit of heat...
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