Types of Fire Extinguishers

The fire extinguisher is a portable, pressurized container that can be used to combat a small fire. Fire extinguishers come in different types and sizes and are designed to put out specific types of fires. It is important to choose the correct type of fire extinguisher for a given situation, and to know how to properly operate one in an emergency.

Internationally, there are several accepted classification methods for hand-held fire extinguishers. Class A extinguishers are designed for solid combustibles, such as wood, paper and cloth. Class B extinguishers are designed for flammable liquids, such as gasoline and oil. Class C fires are caused by electrical hazards, such as faulty wiring and overheated appliances. Class K fires are caused by cooking oils and fats.

Each fire extinguisher is labeled with a picture of a common fire and the specific types of fire it can be used to fight. In addition, the fire extinguisher should have a pressure gauge on it so that the user can determine when it is low or has been used. It is also important to know that not all fires can be put out by a fire extinguisher and to evacuate the area as soon as possible after the fire starts.

In 1912 Pyrene pioneered carbon tetrachloride (CTC) fire extinguishers, which dispensed the liquid from a brass or chrome canister, typically of 1 imperial quart (1 L) or 1 imperial pint (0.6 L) capacity, onto a fire to extinguish it by interfering with the chemical reaction. This was the first fire extinguisher marketed for home use. The vapor and combustion by-products were highly toxic, however, and deaths did occur in confined spaces. Chlorobromomethane (CBM), which was slightly less toxic and more effective than CTC, was introduced in the 1940s and became very popular until the 1960s. Methyl bromide, which is even less toxic than CBM and works by inhibiting the chain reaction, was introduced in the 1970s.

Dry chemical fire extinguishers, commonly referred to as ABC or tri-class, contain powdered materials that separate the three elements of the fire triangle: heat, fuel and oxygen. Monoammonium phosphate is the preferred agent for home fires, but many other types of dry chemical are available.

Ensure that the fire extinguisher is labeled for the type of fire it is meant to be used on, and that it has been tested by an independent testing laboratory. Always keep the manual with the fire extinguisher and read it before each use. Before using the fire extinguisher, move back from the fire so that you are standing a safe distance away, ideally 1.8 to 2.4 m, and aim the nozzle at the base of the fire. Pull the pin at the top of the fire extinguisher to unlock the operating lever and release the agent. Sweep the nozzle from side to side over the fire until it appears to be out. Then, carefully watch the area to see if the fire re-ignites.