What numerical ratings are associated with Class B fire extinguishers?

Class B fire extinguishers are designed to combat fires involving flammable liquids, gases, and greases. The numerical ratings associated with these extinguishers indicate their effectiveness against Class B fires. The ratings stem from standardized testing processes to determine how much area the extinguisher can cover and how effectively it can extinguish fires in that category.

In this context, the numerical ratings of 1B and 640B are significant. A rating of 1B means that the extinguisher can effectively put out a fire covering an area of 1 square foot of flammable liquid. Conversely, a rating of 640B indicates a much greater capacity, signifying that the extinguisher can handle fires covering an area of 640 square feet. This range of ratings allows users to select the appropriate extinguisher based on the size of the potential fire hazard.

The other options, while containing numbers, do not correspond to the recognized rating standards for Class B fire extinguishers. Understanding these ratings is crucial for ensuring that individuals have the right equipment to respond effectively to Class B fire incidents.