What is the preferred fire-fighting agent for flammable liquids?

The preferred fire-fighting agent for flammable liquids is AFFF Class B foam. This type of foam is specifically designed to extinguish fires involving flammable liquids by creating a blanket over the liquid surface, which not only suppresses the flames but also prevents the release of flammable vapors. The foam works by cooling the fuel and cutting off the oxygen supply, making it highly effective in preventing re-ignition.

In contrast, water can be problematic when dealing with flammable liquids, as it may spread the fire or even cause violent reactions with certain substances. Dry chemical powder is effective for suppressing fires but does not provide the vapor suppression that foam offers, which is crucial for preventing a resurgence of the flames. Carbon dioxide, while it can extinguish flames by displacing oxygen, may not effectively control the fire or prevent re-ignition for flammable liquid fires, especially on large or complex incidents. Thus, AFFF Class B foam is established as the best choice for such scenarios.