Dry powder is the preferred agent for which type of fire?

• A. Interior fire
• B. Fuel fire
• C. 3D fire
• D. Brake fire

Answer: (D)

Dry powder is most effective for brake fires because it can reach and cover the hot, confined brake assembly where flames and embers persist. The fine powder blankets the brake lining, rotor, hydraulic fluid residues, and surrounding components, cooling the surfaces and interrupting the chemical reactions that keep the fire going. It also penetrates crevices and voids in the brake system where heat and fuel can hide, reducing the chance of reignition. In addition, powder is non-conductive and creates a physical barrier that helps prevent the ignition of any residual fluids without the risk of splashing or spreading burning liquids, which can be a concern with water or foam near hydraulic components. Interior fires typically require agents that spray and cool inside compartments, and fuel fires are best smothered or cooled with foam where possible; brake fires demand the crusting, penetrating action of dry powder to extinguish the flames in a tightly packed, high-heat area.