Which method involves directing foam onto the surface near the edge of a burning liquid spill so that it rolls across the surface?

• A. Direct method
• B. Roll-on method
• C. Bank-down method
• D. Rain-down method

Answer: (B)

Roll-on foam application creates a rolling blanket across the surface of a burning liquid spill. By directing foam onto the edge, the foam flows out and spans the surface, forming a continuous layer as it rolls. This blanket cools the fuel, displaces vapors, and keeps air from reaching the liquid, which helps suppress the fire and reduces the chance of reignition. It’s especially effective for large spills because it rapidly covers a wide area with a persistent layer, using the foam’s movement to push coverage from the perimeter toward the center. Other methods exist—direct application targets the flames for quick knockdown, rain-down pours foam from above for broad coverage with less control, and bank-down builds a barrier along the edge—but they don’t deliver the same rolling surface blanket across the spill.