How does dry chemical extinguish a fire?

Dry chemical fire extinguishers work primarily by interrupting the chemical chain reaction that fuels the fire. Most fires require a combination of heat, fuel, and oxygen, known as the fire triangle. The dry chemical agent, typically a powder like monoammonium phosphate or sodium bicarbonate, is designed to disrupt this triangle specifically by interrupting the chemical reactions occurring within the flames.

When the dry chemical is discharged, it settles on the fuel and reacts with free radicals in the flames, effectively halting the combustion process. This is particularly effective against Class B (flammable liquids) and Class C (electrical) fires, where stopping the chemical reactions is crucial for extinguishment.

The other methods mentioned in the other options, such as soaking the fire, cooling the flames, or smothering with foam, represent different strategies used with various types of fire extinguishing agents. However, they do not capture the specific action that dry chemical agents take to address the fire by disrupting the chemical reactions actively occurring in the flame.