What type of fire is used for the Class B Fire Rating test?

The Class B Fire Rating test specifically measures the effectiveness of fire extinguishers on flammable liquids, which includes substances like oil and gasoline. n-heptane is a hydrocarbon that is commonly used in testing because it burns easily and represents the characteristics of Class B fuels. This makes n-heptane an ideal choice for evaluating the fire suppression capability of extinguishers designed for flammable liquid fires.

The other types of fires mentioned do not fit the Class B criteria. Wood fires correspond to Class A, which involves ordinary combustibles such as paper and wood. Oil fires could be viewed as more specific instances of Class B fires, but they do not provide the same standardized testing conditions offered by n-heptane. Electrical fires are classified as Class C and involve energized electrical equipment, necessitating different extinguishing agents to prevent electrical shock risks. Thus, n-heptane serves as the standard for testing effectiveness against Class B fires, reinforcing why it is the correct answer.