Carbon dioxide extinguishes work by displacing oxygen, or taking away the oxygen element of the fire triangle. The carbon dioxide is also very cold as it comes out of the extinguisher, so it cools the fuel as well.

Properties of Carbon Dioxide as a Fire Extinguisher:

1. Inert Gas:
Carbon dioxide is an inert gas, which means it does not undergo chemical reactions easily. When carbon dioxide is released onto a fire, it displaces oxygen, which is necessary for combustion. By removing oxygen from the fire, carbon dioxide effectively extinguishes it.

2. High Density:
Carbon dioxide is denser than air, allowing it to form a blanket over the fire. This blanket prevents oxygen from reaching the fuel source, suffocating the fire and stopping it from spreading.

3. Coolant Effect:
When carbon dioxide is released, it absorbs heat from the fire, reducing the temperature of the fuel source. This cooling effect helps to further suppress the flames and prevent reignition.

4. Non-Conductive:
Carbon dioxide is non-conductive, making it safe to use on electrical fires. It does not conduct electricity, allowing it to be used on live electrical equipment without the risk of electric shock.
Overall, the combination of being an inert gas, having a high density, providing a cooling effect, and being non-conductive makes carbon dioxide an excellent fire extinguisher for a wide range of fire types. Its effectiveness and safety in suppressing fires have made it a popular choice in fire protection systems across various industries.