Which material should never be used to extinguish a Class B fire?

A Class B fire involves flammable liquids such as gasoline, oil, and grease. Using water to extinguish a Class B fire is highly dangerous because water is denser than most flammable liquids; when water is thrown on a burning liquid fire, it can cause the burning liquid to splatter and spread the fire, potentially leading to larger flames and more hazardous conditions. This creates a risk of flashback and can endanger both the person trying to extinguish the fire and those nearby.

In contrast, materials like sand, baking soda, and chemical foam are more appropriate for handling a Class B fire. Sand can smother the flames by cutting off the oxygen supply, baking soda can help extinguish small fires by releasing carbon dioxide when heated, and chemical foam is specifically designed for creating a barrier between the fuel and the fire, effectively preventing re-ignition. Understanding the proper methods for extinguishing different classes of fires is essential for safety and efficiency in fire control.