Ammonium Phosphate
An extinguishing agent used in dry-chemical fire extinguishers that can be used on Class A, B, and C fires.
Aqueous Film-Forming Foam (AFFF)
A concentrated aqueous solution of one or more hydrocarbon and/or fluorochemical surfactants that forms a foam capable or producing a vapor-suppressing aqueous film on the surface of hydrocarbon fuels (NFPA 403).
Carbon Dioxide (CO2) Fire Extinguisher
A fire extinguisher that uses carbon dioxide gas as the extinguishing agent. It is rated for use on Class B and C fires.
Cartridge/Cylinder Fire Extinguisher
A fire extinguisher that has the expellant gas in a separate container from the extinguishing agent storage container. The storage container is pressurized by a mechanical action that releases the expellant gas.
Class A Fire
A fire in ordinary combustible materials, such as wood, cloth, paper, rubber, and many plastic (NFPA 10).
Class B Fire
A fire in flammable liquids, combustible liquids, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, alcohols, and flammable gases (NFPA 10, 2007).
Class C Fire
A fire that involves energized electrical equipment (NFPA 10).
Class D Fire
A fire in combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and potassium (NFPA 10).
Class K Fire
A fire in cooking appliance that involves combustible cooking media (vegetable or animal oils and fats) (NFPA 10).
Clean Agent
Electrically nonconducting, volatile, or gaseous fire extinguishment that does not leave a residue upon evaporation (NFPA 2001).
Cylinder
The body of the fire extinguisher where the extinguishing agent is stored.
Dry-Chemical Fire Extinguisher
An extinguisher that uses a mixture of finely divided solid particles to extinguish fires. The agent is usually sodium bicarbonate, potassium bicarbonate, or ammonium phosphate based, with additives being included to provide resistance to packing and mois
Dry-Powder Extinguishing Agent
An extinguishing agent used in putting out Class D fires. Common examples include sodium chloride and graphite-based powders.
Dry-Powder Fire Extinguisher
A fire extinguisher that uses an extinguishing agent in powder or granular form. It is designed to extinguish Class D combustible-metal fires by crusting, smothering, or heat-transferring means.
Extinguishing Agent
A material used to stop the combustion process. Extinguishing agents may include liquids, gases, dry chemical compounds, and dry powder compounds.
Extra (High) Hazard Locations
Occupancies where the total amounts of Class A combustibles and Class B flammables are greater than expected in occupancies classes as ordinary (moderate) hazards.
Film-Forming Fluoroprotein (FFFP) Foam
A protein-based foam concentrate incorporating fluorinated surfactants that forms a foam capable of producing a vapor-suppressing, aqueous film on the surface of hydrocarbon fuels (NFPA 403).
Fire Load
The weight of combustibles in a fire area (measured in ft squared and m squared) or on a floor in buildings and structures, including either contents or building parts, or both (NFPA 914).
Halogenated-Agent Fire Extinguisher
An extinguisher that uses a halogenated extinguishing agent.
Halogenated Extinguishing Agent
A liquefied gas extinguishing agent that puts out fires by chemically interrupting the combustion reaction between the fuel and oxygen.
Halon 1211
A halogenated agent whose chemical name bromochlorodiflueoromethane, CBrClF2; it is a multipurpose, Class ABC-rated agent effective against flammable liquid fires (NFPA 408).
Handle
A trip used for holding and carrying a portable fire extinguisher.
Horn
The tapered discharge nozzle of a carbon dioxide-type fire extinguisher.
Hydrostatic Testing
Pressure testing of a fire extinguisher to verify its strength against unwanted rupture (NFPA 10).
Ignition Point
The minimum temperature at which a substance will burn.
Incipient Stage
The initial or beginning stage of a fire, in which it can be controlled or extinguished by portable extinguishers or small amounts of dry extinguishing agents, without the need for protective clothing or breathing apparatus (NFPA 484).
Light (Low) Hazard Locations
Occupancies where the total amount of combustible materials is less than expected in an ordinary hazard location.
Loaded-Stream Fire Extinguisher
A water-based fire extinguisher that uses an alkali metal salt as a freezing-point depressant.
Locking Mechanism
A device that locks an extinguisher's trigger to prevent its accidental discharge.
Multipurpose Dry-Chemical Fire Extinguisher
A fire extinguisher rated to fight Class A, B, and C fires.
Nozzle
A constricting appliance attached to the end of a fire hose or monitor to increase the water velocity and form a stream (NFPA 1965).
Ordinary (Moderate) Hazard Locations
Occupancies that contain more Class A and Class B materials than are found in light hazard locations.
PASS
Acronym for the steps involved in operating a portable fire extinguisher: Pull pin, Aim nozzle, Squeeze trigger, Sweep across burning fuel.
Polar Solvent
A water-soluble flammable liquid such as alcohol, acetone, ester, and ketone.
Pressure Indicator
A gauge on a pressurized portable fire extinguisher that indicates the internal pressure of the expellant.
Pump Tank Fire Extinguisher
A nonpressurized, manually operated water extinguisher that is rated for use on Class A fires. Discharge pressure is provided by a hand-operated, double-acting piston pump.
Rapid Oxidation
A chemical process that occurs when a fuel is combined with oxygen, resulting in the formation of ash or other waste products and the release of energy as heat and light.
Saponification
The process of converting the fatty acids in cooking oils or fats to soap or foam; the action caused by a Class K fire extinguisher.
Self-Expelling Fire Extinguisher
A fire extinguisher in which the agents have sufficient vapor pressure at normal operating temperatures to expel themselves (NFPA 10).
Stored-Pressure Fire Extinguisher
A fire extinguisher in which both the extinguishing material and the expellant gas are kept in a single container, and that includes a pressure indicator or gauge (NFPA 10).
Stored-Pressure Water-Type Fire Extinguisher
A fire extinguisher in which water or a water-based extinguishing agent is stored under pressure.
Tamper Seal
A retaining device that breaks when the locking mechanism is released.
Trigger
The button or level used to discharge the agent from a portable fire extinguisher.
Underwriters Laboratories, Inc (UL)
The U.S. organization that tests and certifies that fire extinguishers (among many other products) meet established standards. The Canadian equivalent is Underwriters Laboratories of Canada.
Wet-Chemical Extinguishing Agent
An extinguishing agent for Class K fires. It commonly consists of solutions of water and potassium acetate, potassium carbonate, potassium citrate, or any combination thereof.
Wet-Chemical Fire Extinguisher
A fire extinguisher for use on Class K fires that contains a wet-chemical extinguishing agent.
Wetting-Agent Water-Type Fire Extinguisher
An extinguisher that expels water combined with a chemical or chemicals to reduce its surface tension; it is used for Class A fires.
Wheeled Fire Extinguisher
A portable fire extinguisher equipped with a carriage and wheels, which is intended to be transported to the fire by one person (NFPA 10).