What is the primary use of a carbon dioxide (CO2) extinguisher?

The primary use of a carbon dioxide (CO2) extinguisher is to displace oxygen. CO2 extinguishers work by releasing carbon dioxide gas, which does not support combustion. When the gas is deployed onto a fire, it creates an atmosphere that is deficient in oxygen, thus suffocating the flames. This method is particularly effective for certain types of fires, such as electrical and flammable liquids, because CO2 does not leave a residue, making it safe for use on sensitive equipment and in environments where cleanliness is important.

While other options mention related processes, they do not accurately describe the primary function of CO2 extinguishers. For example, CO2 does not primarily absorb heat (which is more characteristic of water-based extinguishers), nor does it cool flames in the conventional sense. It also smothers flames, but the distinguishing factor is that its ability to displace oxygen is what ultimately prevents combustion. Understanding this fundamental property of CO2 is vital for effectively utilizing this type of extinguisher in firefighting scenarios.