Which of the following defines a Class B fire?

A Class B fire is specifically defined as a fire that involves flammable liquids, which include materials such as petrol, oil, solvents, and paints. These substances can ignite and produce a significant amount of heat and flammable vapors, which can spread quickly and make the fire more challenging to control. Understanding this classification is crucial for selecting appropriate firefighting methods and materials. For instance, certain fire extinguishers are explicitly designed for use on Class B fires, often using foam or dry chemical agents that are effective in smothering the flames and preventing the vapor from igniting.

In contrast, the other options refer to different classes of fires. Fires involving solids like wood or paper are classified as Class A fires, whereas fires that involve flammable gases fall under a different classification. Fires involving metals, known as Class D fires, require specific extinguishing agents due to the unique properties of burning metals. Recognizing these categories is essential for effective fire safety management and response strategies.