Class B fires involve which materials?

Class B fires involve which materials?

• A. Fires involving energized electrical equipment
• B. Flammable liquids
• C. Combustible metals
• D. Ordinary combustibles such as wood and paper

Answer: (B)

This question tests how fires are categorized by the fuel involved. Fires that involve flammable liquids fall into the liquid fuels category. These include gasoline, kerosene, solvents, oils, and other hydrocarbon fuels. The reason this category is distinct is that liquid fuels release vapors that continuously feed the flame and can spread across a surface, making the fire behave differently from solid fuels. Water is generally not effective here because it can spread the liquid and keep the fuel hot, prolonging the burn. Effective suppression targets the liquid surface by cooling, or by using agents like foam or dry chemical powders that blanket the fuel and cut off the vapors or the flame’s access to air. In contrast, other fire types involve different fuels and require different suppression approaches (for energized electrical equipment, metals, or ordinary combustibles).

This question tests how fires are categorized by the fuel involved. Fires that involve flammable liquids fall into the liquid fuels category. These include gasoline, kerosene, solvents, oils, and other hydrocarbon fuels. The reason this category is distinct is that liquid fuels release vapors that continuously feed the flame and can spread across a surface, making the fire behave differently from solid fuels. Water is generally not effective here because it can spread the liquid and keep the fuel hot, prolonging the burn. Effective suppression targets the liquid surface by cooling, or by using agents like foam or dry chemical powders that blanket the fuel and cut off the vapors or the flame’s access to air. In contrast, other fire types involve different fuels and require different suppression approaches (for energized electrical equipment, metals, or ordinary combustibles).