This glossary has been compiled by the National Fire Protection Association (  


Authority having jurisdiction. A term used in many standards and codes to refer to the organization, office, or individual responsible for approving equipment, procedures, and construction in a town, county, city or state.

Automatic Sprinkler System
A sprinkler system of pipes with water under pressure that allows water to be discharged immediately when a sprinkler head operates


Carbon monoxide. A toxic gas, odorless and colorless, that produced when substances are incompletely burned.

Combustible. Capable of reacting with oxygen and burning if ignited.

Conduction. Heat transfer within an item or from one to another by direct contact.

Convection. Heat transfer by circulation within a gas or liquid.


Detection Devices
Electrical, pneumatic, thermal, mechanical, or optical sensing instruments, or subcomponents of such instruments, whose purpose is to cause an automatic action upon the occurrence of some preselected event.

Detection System
A system consisting of detectors; controls; control panels; automatic and manual actuating mechanisms; all wiring, piping, and tubing; and all associated equipment that is used to actuate an extinguishing system.


Egress.  A way out or exit.


Fire code. A set of legally adopted rules and regulations designed to prevent fires and protect lives and property.

Fire devil. A small, burning cyclone that results when heated gasses from a fire rise and cooler air rushes into the resulting areas of low pressure; usually occurs during forest and brush fires but also in free-burning structural fires.

Flame over (rollover). The rapid spread of flame over surfaces.

Flammable.  Capable of being readily ignited.

Flashover.  The stage of fire when all surfaces and objects are heated to their ignition temperature (flash point) and flame breaks out almost at once over the entire surface.

Flashpoint. The lowest temperature at which a liquid or solid releases enough vapor to ignite when mixed with air.


H.A.D. Heat actuating devices thermostatically controlled and used to activate fire equipment, alarms, or appliances.

Head of the fire. The main or running edge of a fire, the part of the fire that spreads fastest.

HID Lighting. Lighting, high efficiency & long life high-intensity discharge lighting.

High-Pressure Sodium (HPS). Lamps deliver low operating costs and energy-efficient performance.


IDLH: Immediate Danger to Life and Health. An atmospheric concentration of any toxic, corrosive or asphyxiant substance that poses an immediate threat to life or could cause irreversible or delayed harm to health. There are three IDLH atmospheres: toxic, flammable and oxygen-deficient.

Ignition point. The minimum temperature at which a substance will burn.

Ignition temperature. The minimum temperature at which a fuel, when heated, will ignite in air and continue to burn; the minimum temperature required to for a self-sustained combustion.

Incendiary fire. An intentionally set fire.

Incident Management System. A management structure that can be quickly adapted to any situation, a standard approach with predefined roles, responsibilities, procedures and terminology.

Inspection Testing and Maintenance Services
A service program provided by a qualified contractor or qualified owner’s representative in which all components unique to the property’s systems are inspected and tested at the required times and necessary maintenance is provided. This program includes logging and retention of relevant records.


Life Safety Code.  NFPA 101, the code that describes the structures, equipment, and behaviors that can protect life if there is a fire, such as size and location of exits and the need for regular fire drills.

Lighting Inverters. Converts LED and fluorescent fixtures into code-compliant emergency lighting. It provides an emergency power output of 100W maximum and will support the lighting load for 90 minutes.


National Fire Incident Reporting System, or NFIRS System.  A system by which fire departments provide computerized records of fires and other fire department incidents in a uniform manner.

Notification Appliance
A fire alarm system component such as a bell, horn, speaker, light, or text display that provides audible, tactile, or visible outputs, or any combination thereof.

Nuisance Alarm 
Any alarm caused by mechanical failure, malfunction, improper installation, or lack of proper maintenance, or any alarm activated by a cause that cannot be determined.


Oxidation. A chemical reaction in which an element combines with oxygen. All fires are a form of oxidation.

The Occupational Safety and Health Administration of the U.S. Department of Labor.


Products of combustion. Heat, smoke and toxic gasses.

Protective Systems, Equipment, or Apparatus
Automatic sprinklers, standpipes, carbon dioxide systems, clean agent systems, automatic covers, and other devices used for extinguishing fires.

Pyrolysis. The chemical decomposition of a compound into one or more other substances by heat alone; pyrolysis often precedes combustion.


Radiation. Heat transfer through electromagnetic waves, without objects or gasses carrying it along. Radiated heat goes out in all directions, unnoticed until it strikes an object.

Rollover. The rapid spread of flame over surfaces (also called flame over).


Thermal column. A cylindrical area above a fire in which heated air and gasses rise and travel upward. The magnitude and intensity of a fire can often be judged from the thermal column.

Thermal imaging device. An electronic device that detects differences in temperature based on infrared energy and then generates images based on that data. Commonly used in obscured environments to locate victims.


UPS. An uninterruptible power system, or UPS, is a power source that provides a steady flow of power to an electrical load without interruption until the system can be safely shut down.