Which technique produces the desired foam quality and blankets the surface of a burning liquid?

• A. Roll on technique
• B. Sub-surface injection technique
• C. Drizzle-on technique
• D. Blitz technique

Answer: (A)

Foam extinguishment hinges on creating a stable, continuous film that blankets the liquid surface, cooling the fuel and cutting off the flame’s access to air. The roll-on technique delivers foam as a thick, cohesive layer that spreads across the surface and blankets the entire burn. This produces the right foam quality—stable and viscous enough to hold its shape and spread evenly—so the surface is fully covered and vapor release is suppressed. The blanket remains on the surface, providing effective cooling and sealing of the fuel from air. Other approaches don’t form that long-lasting surface film: injecting foam under the surface doesn’t create a surface blanket, sprinkling or drizzle-on yields a lighter, less stable layer that may not cover the liquid, and high-expansion blitz foam tends to be airy and volumes-focused rather than forming a solid surface seal.