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Fire

A state, process, or instance of combustion in which fuel or other material is ignited and combined with oxygen, producing heat, light, and flame.

Cold Fire

Fire that burns below a temperature of 400°F; these fires are cooler-than-normal, such as an alcohol flame.

Fire Triangle

The classic representation of the elements needed for fire: heat, oxygen, and fuel.

Heat (in fire context)

The energy necessary to raise the temperature of fuel to its ignition point to initiate combustion.

Oxygen

A critical component of combustion, typically found in air at about 21%; necessary for sustaining a fire.

Chemical Chain Reaction (Fire Tetrahedron)

An additional component necessary for fire that sustains the heat needed for combustion.

Ignition

The stage of fire development when the elements required for combustion combine and a fire starts.

Glowing Combustion

A type of combustion where solid fuels do not produce enough gas to sustain a flame.

Flaming Combustion

The most recognizable type of combustion, involving gaseous fuel sources with visible flames.

Spontaneous Combustion

Ignition of material without an external flame, caused by internally generated heat from rapid oxidation.

Explosive Combustion

A type of combustion resulting from vapors or gases that ignite when mixed with air.

Fire Gases

Byproducts of combustion in gaseous form, including carbon monoxide (CO) and carbon dioxide (CO₂).

Smoke

The visible product of incomplete combustion, a mixture of various gases and fine particulate matter.

Flash Point

The lowest temperature at which a liquid produces enough vapor to ignite when exposed to a flame.

Fire Point

The lowest temperature at which a liquid can maintain continuous combustion.

Auto-Ignition Point

The temperature at which a flammable liquid can spontaneously ignite without an external flame.

Oxidation

A chemical change where a fuel reacts with an oxidizer, typically oxygen, resulting in burning.

Pyrolysis

The thermal decomposition of materials at elevated temperatures in the absence of oxygen, producing flammable gases.

Thermal Energy

Energy possessed by a material due to molecular activity; related to the temperature of the material.

Thermal Imbalance

The condition created by the turbulent circulation of smoke and steam, potentially misleading investigators.

Specific Gravity

The ratio of the weight of a solid or substance to the weight of an equal volume of water.

Vapor Density

The weight of a volume of pure gas compared to the weight of an equal volume of dry air at the same temperature and pressure.

Vapor Pressure

The pressure exerted by vapor molecules in equilibrium with its liquid.

Luminous Flame

An orange-red flame indicative of incomplete combustion, emitting soot and lower temperatures.

Non-Luminous Flame

A blue flame indicating complete combustion, producing higher temperatures without soot.

Laminar Flame

A flame where the flow of particles follows a smooth, steady path.

Turbulent Flame

An irregular flame characterized by erratic flows, often resulting from increased physical size or gas velocity.