Co2 Fire Extinguisher

Carbon dioxide fire extinguishers are filled with the non-flammable gas under high pressure. These are primarily used for Class B fires (flammable liquids that are miscible with water) and electrical fires. The CO2 fire extinguisher is a popular choice of portable fire-suppressant as they became a natural replacement for Halon ones when they were taken out of general use.

This type of fire extinguisher can be identified in several ways. Older versions will be black in colour, while newer versions will be red with a black logo somewhere near the top of the canister. CO2 extinguishers have no visible pressure gauge and the exit nozzle is distinguishable as it is a large black horn. They can vary in size from 5lbs to 100lbs or more, and the horn in larger sizes will be attached to a flexible hose.

Co2 Fire ExtinguisherIn a fire where electricity is involved, carbon dioxide is the best choice of extinguisher as unlike dry powder, it leaves no residue behind, so does no damage to equipment such as computers and photocopiers. The gas is capable of entering the body of the equipment involved and thus putting out the fire. It is also often used in restaurants (for Class F fires not involving deep fat cooking fires) as it will not contaminate food or cooking equipment. CO2 is not suitable for Class F fires as it has such a powerful discharge that it could cause a splashback of the hot oil onto the operator.

Other locations where a CO2 extinguisher is suitably placed includes laboratories, mechanical rooms, kitchens and areas with flammable liquids are stored.

CO2 extinguishers are not recommended for Class A fires involving flammable solids as it is unlikely that it will be able to displace enough of the oxygen, so the fire could just re-ignite. For that reason CO2 fire extinguishers are also not recommended for outdoor fires. At the opposite end of the spectrum, this type of extinguisher is also not recommended for fires in confined spaces, as the oxygen depletion could cause asphyxiation in the operator.

How to use a CO2 fire extinguisher

Before operating a CO2 extinguisher, the user must move the discharge horn upwards until it is at a right angle with the canister. The horn itself should not be held during operating as the release of the gas could make a metal horn so cold a human hand will freeze to it. When releasing a CO2 fire extinguisher, always aim the gas at the base of the fire where the gas is being released in order to have the maximum effect. The release of CO2 will also be very noisy.

Like all extinguishers, CO2 fire extinguishers should have a regular visual inspection and also be serviced on an annual basis. Unlike most other types of extinguisher, CO2 canisters will also need to have an overhaul once every ten years. A basic maintenance schedule for a CO2 extinguisher involves checking to see if the extinguisher has been used, if it is damaged, that instructions are still legible, and that all exits on the canister are not blocked. An overhaul is more in depth as it involves a test discharge and a pressure test of the shell of the canister.

Category: Fire Extinguisher Types