Carbon dioxide (CO2) is the gas most commonly used for extinguishing fires.
While fire needs oxygen to burn (fueling the combustion process), CO2 is used to suffocate the fire by displacing the oxygen. This reduction in oxygen concentration smothers the flames and helps to prevent reignition by cooling the fuel.
Here's a breakdown of why CO2 is effective as a fire suppressant:
- Oxygen Displacement: CO2 is heavier than air. When released, it settles around the fire, displacing the oxygen that fuels it.
- Cooling Effect: The rapid expansion of CO2 when released from a pressurized container cools the surrounding area, further inhibiting combustion.
- Non-Combustible: CO2 itself does not burn or support combustion.
- Versatility: CO2 extinguishers are effective on Class B fires (flammable liquids) and Class C fires (electrical fires) because it is a non-conductive gas.
However, it's important to note that other gases and chemicals are also used in fire suppression systems depending on the specific application. Some examples include:
- Nitrogen: Used in some inert gas fire suppression systems, similar to CO2 in displacing oxygen.
- Argon: Another inert gas used in fire suppression, often in combination with nitrogen.
- Clean Agent Fire Suppressants (e.g., FM-200): These are chemical agents that interrupt the combustion process and are often used in areas where water damage from sprinkler systems would be problematic, like data centers.
Therefore, to be perfectly clear, while fire requires oxygen to burn, CO2 is used to put out fires.
