What is the preferred method for extinguishing a Class B fire?

The preferred method for extinguishing a Class B fire, which involves flammable liquids such as gasoline, oil, or grease, is to use foam or dry chemical extinguishers. These types of extinguishers effectively interrupt the chemical reaction of the fire or create a barrier that is effective at suppressing the flames. Foam can smother the fire by forming a blanket over the liquid, preventing the vapors from igniting, while dry chemical extinguishers can disrupt the combustion process, effectively putting out the flames.

Using water to cool the flames is not effective for Class B fires, as it can spread the burning liquid, making the situation worse. Similarly, using sand or dirt might help to smother smaller Class B fires but is not the most effective or reliable method in most cases, especially with larger fires involving flammable liquids. A fire blanket could potentially work on smaller flames, but it is not practical for larger Class B incidents, where specialized extinguishers are required to tackle the flames effectively and safely.