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Oxidation

The combination of oxygen with another substance to produce new substances, often releasing energy.

Energy

The ability of a system to do work; can take forms such as heat and light.

Exothermic Reaction

A reaction that releases more heat energy than is required to initiate it.

Ignition Point

The minimum temperature needed to spontaneously ignite fuel.

Heat of Combustion

The energy released as heat and light when a substance burns.

Fire

A chain reaction that sustains itself through heat, fuel, and oxygen.

Flash Point

The lowest temperature at which a liquid gives off enough vapor to ignite.

Pyrolysis

The decomposition of solid materials by heat to produce flammable gases.

Glowing Combustion / Smoldering

Burning at the fuel-air interface, like in cigarettes or embers.

Conduction

Heat transfer through a solid object (e.g., metals in structures).

Radiation

Heat transfer by electromagnetic waves (e.g., paper igniting at 451°F).

Convection

Heat transfer through movement in gases or liquids (e.g., hot air rising).

Accelerant

A substance used to speed up the spread of fire (e.g., gasoline, kerosene).

Streamers

Materials used to intentionally spread fire from one area to another.

Point of Origin

The location where a fire began, typically showing the most intense burn and located lowest.

Ignition Device

Tool or object used to start a fire (e.g., matches, cigarettes, Molotov cocktails).

Flashover

When all combustible materials in an area ignite at once, engulfing a structure in fire.

Substrate Control

A control sample of similar but uncontaminated material collected at a fire scene.

Headspace

The vapor area inside a sealed container that holds debris samples for accelerant detection.

Charcoal Strip Method

A technique using charcoal to absorb vapors from fire debris for lab analysis.

Gas Chromatograph (GC)

An instrument used to separate and analyze chemical substances in fire debris.

Hydrocarbon

A compound made of only carbon and hydrogen; common in fuels and accelerants.

Ignitable Liquids Reference Hydrocarbon Collection (ILRC)

Online resource of chromatographic patterns for known accelerants.

Explosion

A chemical or mechanical reaction that produces heat and rapid gas expansion.

Explosives

Substances that undergo rapid oxidation to release gas and pressure; classified as high or low.

Low Explosives

Substances like black powder and smokeless powder that deflagrate (burn rapidly).

Deflagration

The rapid burning of a substance, characteristic of low explosives.

High Explosives

Substances like TNT or RDX that detonate and create shock waves.

Detonation

A rapid explosion producing a supersonic shock wave.

Primary Explosives

Highly sensitive materials used to initiate secondary explosives (e.g., blasting caps).

Secondary Explosives

More stable explosives that require a primary explosive to detonate (e.g., TNT, RDX).

TATP (Triacetone Triperoxide)

A volatile homemade explosive made from acetone and peroxide.

RDX

A powerful military explosive commonly found in plastic explosives like C-4.

Ion Mobility Spectrometer (IMS)

A tool for detecting explosive residues by analyzing ion movement through an electric field.

Crater

A depression formed at the explosion's point of origin; evidence is collected from inside.

Color Spot Tests

Chemical tests for detecting explosive residues by color change.

Thin-Layer Chromatography (TLC)

A technique for separating components of explosives or residues.

Gas Chromatography/Mass Spectrometry (GC/MS)

A confirmatory test that identifies substances by mass fragmentation patterns.

IR Spectrophotometry

A technique for confirming explosives by identifying molecular fingerprints.