Which extinguisher is most effective on Class B and Class C fires?

• A. Water Type
• B. Carbon Dioxide Type
• C. Halogenated Hydrocarbon Type
• D. Halon 1301 Type

Answer: (B)

Carbon dioxide extinguishers are especially effective for fires involving flammable liquids and electrical equipment because they work by displacing the surrounding air and starving the flame of oxygen, while being non-conductive. This combination means rapid knockdown on Class B fires (flammable liquids) without leaving residue that could contaminate or damage sensitive equipment, and it allows safe use on live electrical equipment (Class C) since CO2 does not conduct electricity and won’t create a conductive residue. While other types can also suppress these fires, they either rely on cooling or chemical inhibition and can pose risks to people in occupied spaces or to sensitive gear, or require careful handling due to environmental concerns. The ability to quickly suppress the flame in enclosed areas without residue makes CO2 the best overall choice for these fire classes.