What is the most effective method of controlling flammable liquid fires?

Using foam is considered the most effective method of controlling flammable liquid fires because it provides a protective blanket over the burning liquid, effectively suppressing the flames and preventing the release of flammable vapors. Foam works by displacing oxygen, which is necessary for combustion, and forming a barrier that isolates the fuel from the surrounding environment, thus helping to extinguish the fire.

In contrast, using large amounts of water can be ineffective for flammable liquid fires because water does not mix with these liquids and can instead spread the fire, causing it to become larger and more dangerous. Unmanned nozzles might provide some application of water or foam but lack the control necessary for effectively targeting the fire. Allowing the fire to burn undisturbed is a hazardous approach, as it poses significant risks to life and property. Therefore, foam is the most reliable method for safely and effectively managing flammable liquid fires.