What is the main extinguishing agent in a CO2 fire extinguisher?

The main extinguishing agent in a CO2 fire extinguisher is carbon dioxide. CO2 works effectively by displacing oxygen in the area of the fire, which is crucial because fire needs oxygen to sustain combustion. By reducing the available oxygen, CO2 interrupts the chemical reaction in the fire triangle (heat, fuel, and oxygen), which ultimately suppresses the fire.

Additionally, CO2 extinguishers are particularly suitable for fires involving electrical equipment and flammable liquids, as they do not leave any residue and do not conduct electricity. This makes them a preferred choice in environments where protecting equipment and preventing contamination is important. The high density of carbon dioxide allows it to smother the fire rapidly, enhancing its effectiveness as an extinguishing agent.