What is the smell associated with Class B fires?

Class B fires involve flammable liquids, gases, and flammable solids. The characteristic smell associated with these types of fires is that of burnt oil or petrol, which is often accompanied by black smoke. This is due to the nature of the materials involved in these fires, such as solvents, paints, and fuels that emit strong, acrid scents when ignited. Recognizing this distinct odor can be crucial for emergency responders in identifying the type of fire and determining the appropriate actions and extinguishing agents to use.

In contrast, the other options are more aligned with different types of fires. For instance, burnt wood or ashy smells are predominantly associated with Class A fires, which involve solid combustibles like wood, paper, and textiles. Fresh gasoline has a distinct smell that can indicate a dangerous situation but is not characteristic of the burn smells from a Class B fire specifically. Hence, the correct association is with the burnt oil/petrol smell, which aligns with the burning of flammable liquids and gases found in Class B fires.