What is the primary mechanism by which carbon dioxide extinguishers operate?

Carbon dioxide extinguishers operate primarily by displacing oxygen in the environment around the fire, effectively smothering it. Fire requires three elements to sustain combustion: heat, fuel, and oxygen, commonly known as the fire triangle. By reducing the available oxygen to below what is needed for combustion, carbon dioxide extinguishers interrupt this critical part of the triangle, leading to the suppression of the fire.

When carbon dioxide is released from the extinguisher, it expands and cools, but its primary role is in displacing oxygen rather than absorbing heat or cooling the fire as an active method of extinguishment. The dense cloud of carbon dioxide creates an inert atmosphere, which prevents the fire from continuing to burn.

While other mechanisms like cooling the fire or breaking the chemical chain reaction are effective for different types of extinguishers (such as water or dry chemical agents), carbon dioxide specifically targets the oxygen supply, making that its primary method of operation.