Which of the following is NOT a method for extinguishing Class B fires?

In firefighting, Class B fires involve flammable liquids such as gasoline, oil, grease, and solvents. The method chosen for extinguishing these types of fires must be appropriate to prevent the fire from spreading or rekindling.

Water fog, portable PKP (Potassium Bicarbonate Powder), and Halon 1301 are all recognized methods for extinguishing Class B fires. Water fog can help cool the surrounding area and displace oxygen, while PKP effectively interrupts the chemical reaction of the fire. Halon 1301, a gaseous fire suppression agent, also works by interrupting the chemical chain reaction and is effective in putting out Class B fires.

On the other hand, using water spray alone can be dangerous when dealing with Class B fires because water can spread the burning liquid, potentially exacerbating the fire instead of extinguishing it. For this reason, using water spray without additional agents or methods is not an effective means to combat Class B fires. Therefore, this option is not a valid method for extinguishing such fires, making it the correct choice.