What role do dry chemical extinguishers serve in fighting Class B fires?

Dry chemical extinguishers are specifically designed to fight Class B fires, which primarily involve flammable liquids such as gasoline, oil, and grease. The correct answer highlights that these extinguishers work by interrupting the chemical reaction that sustains the fire and smothering the flames.

When a dry chemical extinguisher is deployed, it releases a fine powder, typically composed of substances like sodium bicarbonate, potassium bicarbonate, or monoammonium phosphate. This powder effectively coats the fuel, displacing oxygen and preventing it from continuing to burn. By interrupting the chain reaction that is necessary for combustion, the dry chemical extinguishers effectively suppress the flames and help extinguish the fire.

Understanding this mechanism is crucial for effective fire safety and response, particularly in environments where Class B fire hazards are present. The primary focus of using dry chemical extinguishers is to eliminate the fuel from sustaining the fire, rather than cooling it or adding more materials that could exacerbate the situation.