When trying to extinguish a fire, which method is typically ineffective for Class B fires?

Water application is typically ineffective for Class B fires, which involve flammable liquids such as gasoline, oil, and solvents. The use of water on these types of fires can be dangerous for a couple of reasons. First, water is denser than many flammable liquids, causing it to sink and allowing the flammable liquid to continue burning on the surface. This can lead to the fire spreading rather than being extinguished.

Additionally, water can cause a phenomenon known as a "flashing" effect when it is applied to a burning liquid. This is especially true for burning liquids that flash or vaporize at low temperatures, which can create a larger area of fire and increase the hazardous conditions for firefighters. Therefore, while water might be effective for Class A fires (which involve ordinary combustibles like wood and paper), it is not suitable for Class B fires and can complicate the firefighting efforts.

In contrast, foam suppression, dry chemical suppression, and carbon dioxide usage are effective methods for extinguishing Class B fires. Foam creates a blanket over the burning liquid, cutting off the oxygen supply and preventing vapor release. Dry chemical agents interrupt the chemical reaction of the fire. Carbon dioxide displaces oxygen in the vicinity of the fire, also helping to extingu