Which class of fire is involved when someone drops a lighted cigarette into a can of paint thinner?

The situation described involves a lighted cigarette coming into contact with paint thinner, a flammable liquid. This scenario falls under Class B fires, which are related to flammable and combustible liquids, such as gasoline, oil, paint, and solvents.

Class B fires typically involve substances that can ignite and burn, and paint thinner is highly flammable. The presence of an ignition source, in this case, the lighted cigarette, can easily cause a Class B fire to ignite, leading to a potentially dangerous situation. Understanding the classification of fire types is crucial for effective fire prevention and response strategies, especially for security personnel who may encounter such risks in their environments.

Classes A, C, and D refer to different types of materials and situations; for instance, Class A fires involve ordinary combustibles like wood and paper, Class C is for electrical fires, and Class D pertains to fires involving combustible metals. Thus, they do not apply to the scenario of a lighted cigarette igniting a flammable liquid.