Principles of Foam Fire Fighting (1st Edition)
Chapter 1 Terms
Important Fire Behavior Considerations Related to Foam Applications

Backdraft
Condition created by a sudden inflow of fresh air to an oxygen-deficient smoldering fire which creates an explosion.

British Thermal Unit
The amount of heat required to raise one pound of water one degree Fahrenheit.

Class C Fire
Fires involving energized electrical equipment.

Class D Fire
Fires involving combustible metals.

Conduction
Transfer of heat through direct contact between two objects or through contact with an intervening medium that transfers heat.

Conductivity
The ability of a substance to conduct an electrical current.

Convection
Transfer of heat by the movement of fluids such as air or water.

Density
Weight per unit volume of a substance which is obtained by dividing the weight by volume.

Explosive Limit
Percentage of a substance in air that will burn once ignited.  Synonymous with Flammable Limit.

Explosive Range
The range between the upper flammable limit (UEL) and lower flammable limit (LEL) in which a substance can be ignited.  Synonymous with Flammable Range.

Fire Tetrahedron
Model of the four elements required to have a fire in which the four sides represent fuel, heat, oxygen, and chemical chain reaction.

Fire Triangle
Plane geometric figure in which the three sides of an equilateral triangle represent oxygen, heat, and fuel, the elements necessary to sustain combustion.

Flammable Limit
Percentage of a substance in air that will burn once ignited.  Synonymous with Explosive Limit.

Flammable Liquid
Any liquid having a flash point below 100^oF and having a vapor pressure not exceeding 40psi absolute.

Flashover
Stage of fire at which all surfaces and objects within a space have been heated to their ignition temperature and flame breaks out almost at once over the surface of all objects in the space.

Foam
Extinguishing agent formed by mixing foam concentrate with water and aerating the solution for expansion.  Also known as finished foam.

Free-Burning Phase
Generally considered the phase of the fire where sufficient oxygen and fuel are available for fire growth and open burning to a point where total involvement is possible.  Synonymous with Steady-State Phase.

Hot-Smoldering Phase
Phase of combustion when the level of oxygen in a confined space is below that needed for flaming combustion and is characterized by glowing embers, high heat at all levels of the room, and heavy smoke and fire gas production.

Immiscible
Not capable of mixing together.

Incipient Phase
First phase of the burning process where the substance being oxidized is producing some heat, but the heat has not spread to other substances nearby and the oxygen in air has not been significantly reduced.

Incompressible
Inability to be compressed into a smaller space.

Inorganic Acid
An acid that generally does not contain carbon and will not burn.

Joule
The amount of heat energy provided by one watt flowing for one second.

Miscible
The ability to mix together.

Organic Acid
An acid that contains carbon and will burn.

Oxidation
Chemical reaction in which oxygen combines with other elements.

Oxidizer
Substance that yields oxygen readily and may simulate the combustion of organic and inorganic matter.

Polar Solvents
Flammable liquids that have an attraction to water.

Positive Heat Balance
Situation in which heat is fed back to the fuel.

Purge
The process of emptying.

Pyrolysis
Chemical decomposition caused by heat that generally results in the lowered ignition temperature of a material.

Radiation
Transfer of heat through heat waves (infrared).

Radiative Feedback
Radiant heat providing energy for continued vaporization.

Residual Fuel
Unburned fuel left behind after a fire.

Rollover
Unburned superheated combustible gases released during the incipient or early steady-state phase that accumulate at ceiling level and are pushed, under pressure, away from the fire area and into uninvolved areas where they mix with oxygen and ignite once reaching their ignition temperature resulting in flames rolling across the ceiling.

Solubility
Degree to which a solid, liquid, or gas dissolves in a solvent.

Specific Gravity
Weight of a substance compared to the weight of an equal volume of water at a given temperature.

Steady-State Burning Phase
Generally considered the phase of the fire where sufficient oxygen and fuel are available for fire growth and open burning to a point where total involvement is possible.  Synonymous with Free-Burning Phase.

Surface-to-Mass Ratio
The ratio of the surface area of a fuel in relation to the mass of the fuel.

Vapor Density
Weight of a given volume of gas or vapor compared to the weight of and equal volume of air at the same temperature and pressure.

Vaporization
Passage from a liquid to a gaseous state.

Viscosity
A liquid's thickness or ability to flow.

Volume
The space occupied by a substance.