Class B extinguisher ratings: what does 1-B to 140-B indicate about the extinguishing capacity?

• A. Each 1-B can extinguish 1 square foot
• B. Each 1-B can extinguish 0.25 square meters
• C. Each 1-B can extinguish 2 square feet
• D. Each 1-B can extinguish 1 square foot or 0.09 m2

Answer: (D)

Class B ratings express the area of a hydrocarbon fire that a standard extinguisher can handle. For each B unit, the tested extinguishing area is about 1 square foot, which is roughly 0.093 square meters. So the rating 1-B to 140-B means the extinguisher can cover areas from about 1 ft2 up to about 140 ft2, with the basic unit being about 1 ft2 (0.09 m2). That makes the statement that one B unit extinguishes 1 square foot or 0.09 m2 the correct interpretation. Other options don’t align with the standard area-based rating (they mix up metric conversions or square-foot values).