What is the function of CO2 as an extinguishing agent?

The role of carbon dioxide (CO2) as an extinguishing agent primarily involves its ability to displace oxygen in the environment where the fire is burning. Fires require three elements to sustain combustion: heat, fuel, and oxygen. By increasing the concentration of CO2 in the area of the fire, the available oxygen is effectively reduced, which interrupts the combustion process. This action suffocates the fire, leading to its extinguishment.

CO2 is particularly effective in extinguishing fires in enclosed spaces, as it is non-toxic in low concentrations and does not leave any residue, making it suitable for use on electronic equipment and valuable assets. This characteristic makes it a preferred choice in many scenarios, including in fire protection systems for data centers, laboratories, and other environments where water or foam might cause damage to sensitive equipment.

While cooling a fire and forming a vapor barrier are important tactics in fire suppression, they do not specifically describe the primary mechanism by which CO2 operates. CO2 does not cool the fire as effectively as water or other agents, nor does it form a vapor barrier; it functions mainly through the displacement of oxygen, making this the most accurate function for CO2 in fire suppression.