What type of extinguisher is preferred for combating a Class B fire?

The preferred choice for combating a Class B fire, which involves flammable liquids such as gasoline, oil, and grease, is foam or dry chemical extinguishers. Foam extinguishers work by creating a barrier between the fuel and the fire, effectively suppressing the flames and preventing re-ignition. Dry chemical extinguishers are also highly effective as they work by interrupting the chemical reaction of the fire, forming a blanket over the burning liquid to smother the flames.

Using a water extinguisher is generally ineffective and potentially dangerous on Class B fires, as water can spread the flammable liquid and exacerbate the fire. CO2 extinguishers can be used on Class B fires, but they may not provide sufficient cooling effect or prevent re-ignition as effectively as foam or dry chemical options. Halon extinguishers are effective but are less commonly used today due to environmental concerns. Therefore, foam and dry chemical extinguishers are the most reliable and safest options for addressing Class B fires.