What is the preferred extinguishing agent for Class Bravo fires, which involve flammable liquids?

For Class B fires, which involve flammable liquids such as gasoline, oil, and solvents, the preferred extinguishing agents are those that can effectively smother the fire and prevent re-ignition. Aqueous Film Forming Foam (AFFF) is highly effective because it forms a film over the burning liquid, cutting off the oxygen supply and preventing vapors from igniting. This makes AFFF particularly suitable for tackling flammable liquid fires.

Additionally, firefighting agents like Powdered Potassium Bicarbonate (PKP) and Carbon Dioxide (CO2) are also effective for Class B fires. PKP works by disrupting the combustion process, while CO2 displaces oxygen in the vicinity of the fire, effectively suffocating it.

Given that both AFFF and the combination of PKP and CO2 are preferred extinguishing agents for Class B fires, the response encompassing both AFFF and the other agents is the most comprehensive and accurate choice for extinguishing flammable liquid fires. This combination allows for flexibility in firefighting strategies depending on the specific circumstances of the fire.