Which mechanism is used by carbon dioxide to extinguish a fire?

Carbon dioxide extinguishes a fire primarily by displacing oxygen, which is essential for combustion. When carbon dioxide is released into an area where a fire is burning, it reduces the concentration of oxygen in the vicinity of the flames. Since fire needs a specific amount of oxygen to sustain combustion, reducing the oxygen level below the threshold necessary for fire to continue burning effectively suffocates the flames. This method is particularly effective in enclosed spaces where oxygen can become depleted quickly.

In contrast, mechanisms such as cooling the fuel or creating a vapor barrier do not apply to carbon dioxide’s extinguishing method. Cooling, for instance, typically involves the use of water or other agents that absorb heat, while a vapor barrier is commonly associated with agents that disrupt the vaporization of the fuel rather than simply displacing oxygen. Removing the fuel refers to eliminating the combustible materials from the fire triangle, which is not directly relevant to the action that carbon dioxide takes in fire suppression. Thus, the displacement of oxygen is the key principle behind how carbon dioxide effectively extinguishes fires.