NICET Special Hazards key terms

A volatile or gaseous fire extinguishing agent that does not leave a residue and is safe for use in occupied spaces when applied at its listed design concentration. Examples include HFC-227ea, FK-5-1-12, and IG-541.

A fire suppression system that discharges carbon dioxide to displace oxygen and absorb heat. Because CO2 can injure or kill people, it is typically limited to unoccupied spaces with warning signs and lockout controls.

A system that proportionally mixes foam concentrate with water and discharges expanded foam onto flammable liquid fires, forming a blanket that seals vapors and cools the fuel.

A water-based system with open sprinklers or nozzles; a detection system opens a deluge valve to discharge water simultaneously from all connected devices over the protected area.

A sprinkler system where the piping is normally dry and a detection event opens a valve to fill the pipe before sprinkler operation; double-interlock versions also require a sprinkler to fuse.

A system that discharges a powdered extinguishing agent, usually sodium bicarbonate or monoammonium phosphate, to interrupt the combustion chain reaction, commonly used for flammable liquid or gas hazards.

A system that discharges an alkaline liquid agent onto cooking media fires, saponifying fats and cooling the surface. Typically installed for commercial cooking equipment and exhaust hoods.

A system that discharges very fine water droplets to extinguish or control fire through cooling, oxygen displacement, and surface wetting while using less water than conventional sprinklers.

A system that generates a suspended aerosol of solid particles, often from a condensed or dispersed aerosol generator, to interrupt the flame chemistry in an enclosed space.

A system that detects a developing explosion and rapidly discharges extinguishing agent into the protected volume to stop the pressure rise before it reaches damaging levels.

A fire involving cooking oils and fats in commercial cooking equipment, requiring a wet chemical agent that saponifies the fuel and cools it below its auto-ignition temperature.

A condition where finely divided solid particles can ignite and propagate a deflagration, often requiring explosion prevention, suppression, or venting in addition to extinguishing systems.

A detection method using a cable or tubing that responds to a rise in temperature along its length, useful in special hazard spaces such as cable trays and storage areas.

A detection method that continuously draws air from a protected area through tubing to a sensitive detector, providing early warning in spaces where point smoke detectors are impractical.

The concentration of extinguishing agent, specified by the listing or manufacturer, that is required to extinguish a fire in the protected space and is used to calculate agent quantity.

The period during which a clean agent concentration must remain above the minimum design concentration in an enclosure, typically measured after discharge to ensure extinguishment.

The time allowed for a system to release its extinguishing agent after actuation, established by the applicable standard and used to size piping, nozzles, and agent supply.

A door fan or pressurization test that measures air leakage of a protected room to verify it can hold the design concentration for the required hold time.

A device installed in a protected enclosure that relieves the pressure increase created by agent discharge and prevents damage to walls, doors, or other building components.

A calculation that determines pipe sizes, flow rates, and pressure losses through a system so the required agent or water delivery rate reaches each nozzle.

The process of mixing foam concentrate with water at a controlled percentage, such as 3% or 6%, to produce a foam solution for discharge.

The ratio of the volume of finished foam to the volume of foam solution from which it is made, used to classify low-, medium-, and high-expansion foams.

The amount of extinguishing agent or water applied per unit area or volume over a given time, used to size a special hazard system for the expected fire.

A system with fixed design, components, and pipe/nozzle limits that is listed as a unit and installed without calculating the design for each application.

A detection arrangement where two independent detectors must both actuate before the system discharges, reducing false discharges while still providing rapid response.

A test conducted after installation to verify that the system performs as designed, including detection, actuation, discharge, and alarm functions, before the system is placed in service.

A periodic pressure test of an agent cylinder to verify it can safely contain pressure; performed at the interval specified by the applicable standard or manufacturer.

A test that operates the system's actuation and release mechanism, often without discharging agent, to confirm valves, linkages, and controls function correctly.

A documented process for taking a system out of service, notifying affected parties, providing alternative protection, and restoring and testing the system before it is returned to service.

The standard for clean agent fire extinguishing systems, covering agent selection, design concentration, enclosure requirements, installation, testing, and maintenance.

The standard for low-, medium-, and high-expansion foam systems, covering foam concentrate selection, proportioning, discharge devices, and system design and testing.

The standard for carbon dioxide extinguishing systems, covering design, installation, operation, and maintenance for total-flooding and local application systems.

The standard for wet chemical extinguishing systems, primarily covering commercial cooking equipment, including design, installation, and maintenance requirements.

The standard for water mist fire protection systems, covering design, installation, acceptance testing, and maintenance, including system types and nozzle requirements.

The standard for explosion prevention and protection systems, covering deflagration prevention, suppression, venting, and related controls for combustible dust and gas hazards.

The formal certification by an approved testing organization that a product or system meets a published standard and is suitable for its intended use.

The organization or individual responsible for enforcing code requirements and approving installations, tests, and plans for a special hazard system.

A written description of how the system responds to each detection or alarm event, including alarm signaling, valve operation, agent discharge, and shutdown actions.

Drawings prepared after installation that document the actual locations of piping, nozzles, detectors, and equipment, used for future maintenance and modifications.