How does a Class D extinguisher extinguish a Class D fire?

A Class D extinguisher is specifically designed to combat fires involving combustible metals, such as magnesium, titanium, and sodium. It operates by smothering the fire, which means it forms a barrier between the burning material and the oxygen in the air. This type of extinguisher often contains a dry powder agent that is effective in preventing the fire from receiving the oxygen necessary for combustion.

Unlike other classes of fire, where cooling (like in water-based extinguishers) or displacing oxygen (like in CO2 extinguishers) may be effective, Class D fires require a unique approach since water can react violently with some combustible metals. Class D extinguishers interrupt the combustion process by smothering the fire with the powder, effectively choking off the fire's access to oxygen needed to sustain the reaction.

Understanding that the mechanism behind a Class D extinguisher is smothering is crucial for proper fire safety and prevention strategies when dealing with flammable metals.