What is the difference between Class A fires and Class B fires?

• A. They Are The Same
• B. Class A Fires Require Water; Class B Fires Require Foam
• C. Class A Fires Involve Ordinary Combustibles; Class B Fires Involve Flammable Liquids
• D. Class B Fires Involve Metals

Answer: (C)

The difference being tested is the type of fuel that feeds the fire. Fires that involve ordinary combustibles—things like wood, paper, cloth, and cardboard—are Class A. Fires that involve flammable liquids—gasoline, oil, solvents—are Class B. This distinction matters because it guides how you fight the fire: on Class A fires, cooling with water is effective because it lowers the material’s temperature and stops the burning; on Class B fires, water can spread the liquid and spread the fire, so extinguishing agents that blanket or separate the fuel from the air (like foam, dry chemical powders, or vapor-suppressing agents) are used instead. Metals require a different classification and special extinguishing methods, so they’re not included in Class B. So, the correct understanding is that one class involves ordinary combustibles and the other involves flammable liquids.