Carbon dioxide fire extinguishers, or CO2 fire extinguishers, are so named because they contain carbon dioxide, which can be used to put out fires. Because CO2 cannot displace enough oxygen to put out an ordinary fire, such as a fire burning wood or paper, they are not recommended for these types of fires. However, CO2 fire extinguishers are useful for putting out other types of fires.
Flammable Liquids
You can use a CO2 fire extinguisher to put out fires that are burning flammable liquids, according to Fire Extinguisher 101. These are known as "class B" fires, and usually involve a liquid such as gasoline or kerosene. CO2 fire extinguishers or other chemical fire extinguishers are preferred for these types of fires because water is more likely simply to spread a flammable liquids fire than to extinguish it.
Electrical Fires
Electrical fires, or "class C" fires, are those that start in electrical systems. They may involve the wiring in a house or in any appliance or item that uses electricity, such as toasters or stereos. While several different types of chemical fire extinguisher can be used to handle an electrical fire, CO2 fire extinguishers are often preferred because they leave behind no chemical residues that can harm electrical equipment.
Fires in Closed Spaces
According to the U.S. Environmental Protection Agency, or EPA, CO2 fire extinguishers and fire systems containing CO2 are preferred in some enclosed spaces, such as on Navy vessels and in manufacturing plants. They are regularly used, for example, in aluminum manufacturing plants. CO2 fire extinguishers have the benefit of not using compressed gas, which makes them less likely to explode if accidentally heated or punctured. However, the concentration of CO2 needed to put out a large fire in a closed space can be lethal to anyone still in the space.
