What technique is recommended for foam application over open ground?

The recommended technique for foam application over open ground is the Sweep or Roll-on method. This technique involves applying foam in a sweeping motion, which helps to effectively cover the surface of the fire and create a barrier between the flames and any potential fuel sources. The application is done from the lowest point of the fire upward and across the area to ensure the foam coats and smothers combustible materials, preventing reignition.

The Sweep or Roll-on method is particularly effective in controlling surface fires because it allows for a more even distribution of foam, which is critical in maximizing its extinguishing effectiveness. This method also helps in avoiding the disruption of the foam blanket that might occur with more aggressive application techniques. By using this method, firefighters can create a protective film that aids in cooling the area while simultaneously smothering the flames.

In contrast, the other methods either do not provide the same level of coverage, may not effectively suppress the fire, or are better suited for different scenarios. The Rain-down method could disperse foam over a wider area but may not concentrate its effectiveness directly on the fuel. The Bank-down method is generally used for vertical surfaces or walls and is not ideal for open ground fires. Direct application can work, but it may lead to less efficient foam distribution