Which foam application method is best for a pool of flammable liquid on open ground?

The roll-in method is considered the most effective for applying foam on a pool of flammable liquid on open ground. This technique involves directing the foam at the edge of the liquid, causing it to roll across the surface in a way that gently blankets the entire area. This helps to reduce the potential for ignition by effectively smothering the vapors and preventing them from escaping into the atmosphere.

In situations involving flammable liquids, creating a blanket of foam over the surface is critical to suppressing flare-ups and protecting nearby exposures. The roll-in method allows for a concentrated application of foam, maximizing its contact with the burning surface and minimizing turbulence, which could disturb burning vapors and re-ignite the fire.

Other methods, such as bounce-off and bank-down, may disperse foam in a way that is less effective for surface coverage. The rain-down application could lead to excessive turbulence and allows vapors to escape, making it less ideal for containing and extinguishing flammable liquid fires. Therefore, roll-in strategically blankets the fuel, providing optimal fire suppression.