Glossary: Common Terms Used in Fire Investigation

Accelerant: An agent, often an ignitable liquid, used to initiate a fire or increase the rate of growth or spread of fire.

Area of Origin: A structure, part of a structure, or general geographic location within a fire scene, in which the “point of origin” of a fire or explosion is reasonably¬† believed to be located.

Backdraft: An explosion resulting from the sudden introduction of air (i.e., oxygen) into a confined space containing oxygen-deficient superheated products of incomplete combustion.

Cause: The circumstances, conditions, or agencies that bring together a fuel, ignition source, and oxidizer (such as air or oxygen) resulting in a fire or a combustion explosion.

Combustible Liquid: A liquid having a flash point at or above 100 degrees F (37.8 degrees C).

Combustion: Capable of burning, generally in air under normal conditions of ambient temperature and pressure, unless otherwise specified. Combustion can occur in cases where an oxidizer other than the oxygen in the air is present (e.g., chlorine, fluorine, or chemicals containing oxygen in their structure.

Conduction: Heat transfer to another body or within a body by direct contact.

Convection: Heat transfer by circulation within a medium such as a gas or a liquid.

CFEI: Certified Fire and Explosion Investigator

CCFI: Canadian Certified Fire Investigator

CTT: Certified Technician/Technologist

 EIT: Engineer in Training

Fire: A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities.

Fire Analysis: the process of determining the origin, cause, development, and responsibility as well as the failure analysis of a fire or explosion.

Fire Dynamics: the detailed study of how chemistry, fire science, and the engineering disciplines of fluid mechanics and heat transfer interact to influence fire behavior.

Fire Investigation: The process of determining the origin, cause, and development of a fire or explosion.

Fire Scene Reconstruction: The process of recreating the physical scene during fire scene analysis through the removal of debris and the replacement of contents or structural elements in their pre-fire positions.

Flame: The luminous portion of burning gases or vapors.

Flammable Liquid: A liquid having a flash point below 100 degrees F (37.8 degrees C).

Flash Point of a Liquid: The lowest temperature of a liquid, as determined by specific laboratory tests, at which the liquid gives off vapors at a sufficient rate to support a momentary flame across its surface.

Fuel: A material that yields heat through combustion.

Fuel Load: the total quantity of combustible contents of a building, space, or fire area, including interior finish and trim, expressed in heat units or the equivalent weight in wood.

Heat: A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state.

Heat of Ignition: The heat energy that brings about ignition.

IAAI-CFI: International Association of Arson Investigators – Certified Fire Investigator

Ignitable Liquid: Any liquid or the liquid phase of any material that is capable of fueling a fire, including a flammable liquid, combustible liquid, or any other material that can be liquefied and burned.

Ignition: The process of initiating self-sustained combustion.

Material First Ignited: The fuel that is first set on fire by the heat of ignition.

NFPA 921: Guide for Fire and Explosion Investigations: A component document of the National Fire Codes promulgated and published by the National Fire Protection Association. The National Association of Fire Investigators considers NFPA 921 as the definitive standard on fire investigation methodology, technology, and science. NFPA 921 is written by the NFPA Technical Committee on Fire Investigations. The Technical Committee consists of up to thirty principal (voting) members and their alternates, appointed by the NFPA Board of Directors from those “vitally interested, qualified, and active” in the area of fire and explosion investigation.

Point of Origin: The exact physical location within the area of origin where a heat source and the fuel interact, resulting in a fire or explosion.

Pyrolysis: A process in whcih material is decomposed, or broken down, into simpler molecular compounds by the effect of heat alone; pyrolysis ofter precedes combustion.

Radiant Heat: Heat energy carried by electromagnetic waves longer than light waves and shorter than radio waves; radiant heat (electromagnetic radiation) increases the sensible temperature of any substance capable of absorbing the radiation, especially solid and opaque objects.

Radiation: Heat transfer by way of electromagnetic energy.

Rekindle: A return to flaming combustion after apparent but incomplete extinguishment.

Scientific Method: The systematic pursuit of knowledge involving the recognition and formulation of a problem, the collection of data through observation and experiment, and the formulation and testing of a hypothesis.

Smoke: An airborne particulate product of incomplete combustion suspended in gases, vapors, or solids and liquid aerosols.

Smoldering: Combustion without flame, usually with incandescence and smoke.

Spalling: Chipping or pitting of concrete or masonry surfaces.

Spontaneous Heating: Process whereby a material increases in temperature without drawing heat from its surroundings.

Spontaneous Ignition: Ignition resulting from self heating. Synonymous with spontaneous ignition.

Vapor: The gas phase of a substance, particularly of those that are normally liquids or solids at ordinary temperatures.

Venting: The escape of smoke and heat through openings in a building.