What is the most effective method to extinguish a Class B fire?

The most effective method to extinguish a Class B fire is by cutting off the oxygen supply or removing the fuel source. Class B fires involve flammable liquids or gases, such as gasoline, oil, and solvents. To effectively suppress these types of fires, it is crucial to eliminate either the fuel or the oxygen, as both are essential components of the fire triangle (fuel, heat, and oxygen).

By removing the fuel source, you prevent the fire from having any material to burn. Alternatively, cutting off the oxygen supply can be done by using materials that can effectively smother the fire, which is why methods such as using a blanket may also be relevant, but this is essentially part of the broader strategy of controlling oxygen levels.

Pouring water directly on a Class B fire is dangerous and not effective, as water can cause flammable liquids to spread and exacerbate the fire. Using a Class A extinguisher is inappropriate for Class B fires, since it is designed for ordinary combustible materials and does not address the unique needs of flammable liquids. Thus, the approach of cutting off the oxygen supply or removing the fuel source ensures that the fire cannot sustain itself, making it a reliable method for extinguishing a Class B fire.