Which classes of fire extinguishers include numbers in their classification?

Which classes of fire extinguishers include numbers in their classification?

• A. A & B
• B. A, B, C
• C. A only
• D. B only

Answer: (A)

Numbers on extinguisher ratings show how much fire each device can handle for that class. For ordinary combustibles like wood and paper, the rating uses a number to reflect the extinguisher’s capacity in terms of water equivalence—the higher the number, the more solid fuel it can suppress. For flammable liquids, the rating also uses a number, indicating the size of a flammable-liquid fire it can control; again, a larger number means greater capability. Other fire types—electrical, metal, and kitchen oils—are labeled with letters alone and don’t carry a numeric rating. So the classes that include numbers are the ones dealing with ordinary combustibles and with flammable liquids.