Which agent is preferred for brake fires?

• A. Water
• B. Foam
• C. Dry chemical
• D. Dry powder

Answer: (D)

Brake fires are driven by extreme heat in a confined brake area mixed with burning hydraulic fluid, so you want an agent that can quickly blanket and smother the flame in tight spaces. Dry powder is best here because it flows into the crevices around the brake disks and calipers, coats the hot surfaces, and forms a crust that isolates the fuel from the air while absorbing heat. This helps prevent re-ignition and sticks where other agents might wash away or fail to penetrate the gaps. Foam can blanket and cool, but it often struggles to reach all the hotspots inside the wheel well’s narrow geometry. Water cools but can spread burning hydraulic fluid and doesn’t smother as effectively. Dry chemical can extinguish, but dry powder’s tendency to cling to surfaces and penetrate tight areas makes it more reliable for brake assemblies.