Fire Extinguisher Chemicals Explained

A fire extinguisher is a necessity in all offices and homes. They are safety devices that can protect you in a case of emergency. It is important to place a fire extinguisher in every area of your home, so no matter where the fire starts, you will have on nearby. Fire extinguishers contain various chemicals that help in putting out the fire effectively. The following will help you understand how each unique type of fire extinguisher works.

Handled fire extinguishers

Handled fire extinguishers contain chemicals like carbon dioxide and nitrogen that force a stream of fire-squelching agent on the fire. You can easily get a handled fire extinguisher in a local hardware store to use in your kitchen and garage.  The material used can be a powder such as potassium bicarbonate (KHCO₃), an evaporating fluorocarbon, liquid water or the propelling agent itself.

Earlier, handled fire extinguishers contained the most effective fluorocarbon called bromochlorodifluoromethane, which was banned in 1994 by the international agreement. The main reason behind this was that the bromine and chlorine atoms present in these chemicals affected the stratosphere, depleting the ozone layer.

Simple fire extinguisher

The simple fire extinguishers contain sodium bicarbonate and sulphuric acid that produce carbon dioxide to extinguish fire. Sodium bicarbonate is a regular dry chemical which is non-conductive, non-toxic and non-corrosive. These fire extinguishers contain a small pouch that carries the acid. The small pouch averts the contact between sodium bicarbonate and the acid. Once the bottle is shaken, the chemical comes in contact with the acid, liberating carbon dioxide and water that help in extinguishing the fire. Simple fire extinguishers with sodium bicarbonate are used in laboratories, household kitchens and garages.

Fire extinguisher containing Carbon Tetrachloride

Another type of fire extinguisher uses compressed Carbon Tetrachloride. This fire extinguisher works when the nozzle is pressed and an aerosol of carbon tetrachloride is passed out that extinguishes the fire. The main advantage of this chemical is that it can be used to extinguish fire of electric circuits and oils.

Water fire extinguishers

Water sprinklers are another form of fire extinguishers. They are the most common and reliable. They are a fixed system which is safe to use and also safe for people. However, water cannot be used for large fires because it is conductive. It is impractical and occasionally ineffective when space is limited, like in airplanes. Water sprinklers are used in schools, stockrooms; offices etc. In places where space is limited, fire extinguishers use different materials which flood a protected section with fire-fighting gas. Even carbon dioxide works well in such situations, but it is avoided in the presence of people as it can prove to be fatal.

Manufacturers have also introduced other chemicals free from bromine and chlorine called hydrofluorocarbons (HFCs) having similar physical properties like halons and are not harmful to the ozone layer. However, hydrofluorocarbons do not extinguish fire like chlorine and bromine. They extinguish fire in the same manner as carbon dioxide and nitrogen oxide by soaking up the heat in the fire and reduce oxygen.