Which type of extinguisher is typically used for Class B fires?

• A. Water spray or foam
• B. CO2 extinguisher or dry chemical extinguisher
• C. Class D powder
• D. Halon alternative

Answer: (B)

When dealing with flammable-liquid fires, you want extinguishing methods that either smother the flame or interrupt the chemical reactions at the flame surface. Carbon dioxide extinguishers work by displacing the surrounding air, effectively suffocating the fire in small, enclosed areas, and they don’t leave conductive residue. Dry chemical extinguishers release powder that disrupts the chemical reactions taking place in the flame and creates a barrier on the liquid surface, helping to prevent vapor release and reignition. Together, these are practical, commonly available options for Class B fires because they directly address the fuel and the flame chemistry without complicating cleanup. Water spray or foam is less ideal for many hydrocarbon fires since water can spread flammable liquids and perpetuate the spread, Class D powders are for metal fires, and halon alternatives are typically used for electrical/equipment fires rather than regular Class B liquid fires.