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[[File:FireExtinguisherABC.jpg|thumb|right|A fire extinguisher]]A '''fire extinguisher''' is a handheld, typically cylindrical, device used to extinguish small [[fire]]s. Such devices contain a fire-suppressive agent, typically under pressure, and are used by spraying this suppressive agent over the base of a fire, smothering the fire out. Fire extinguishers are typically used in an emergency, and should not be wasted on routine, controlled fires (such as a [[campfire]]).

[[File:FireExtinguisherABC.jpg|thumb|right|A fire extinguisher]]A '''fire extinguisher''' is a handheld, typically cylindrical, device used to extinguish small [[fire]]s. Such devices contain a fire-suppressive agent, either under constant pressure or with the ability to quickly pressurize, and are used by spraying this suppressive agent over the base of a fire, smothering the fire. Modern extinguishers are almost always under constant pressure, but some (especially older types) use a chemical reaction to create a propellant gas.  This kind must be turned upside-down when used to create the needed pressure.  Fire extinguishers are generally used in an emergency, and should not be wasted on routine, controlled fires (such as a [[campfire]]).

Modern fire extinguishers are rated for the types of fires they are effective against:  

Modern fire extinguishers are rated for the types of fires they are effective against: