IICRC Health and Safety Technician (HST) certification Practice Exam

The classification of fire extinguishers is based on the types of materials that are involved in the fire. Fires involving cooking oils and fats are categorized as Class K fires. Class K extinguishers are specifically designed to combat kitchen fires that arise from these combustible cooking agents, as they have distinct properties and require specialized methods for effective suppression.

Class K extinguishers typically contain agents such as wet chemical agents that not only extinguish the flames but also create a barrier which safely cools and prevents re-ignition of the hot oils. This effectiveness is essential in a kitchen environment where cooking oils can reach high temperatures and become flammable.

In contrast, Class A extinguishers are meant for ordinary combustibles such as wood, paper, and cloth; Class B is designed for flammable liquids like gasoline; and Class C is used for electrical fires. Therefore, while all these classes serve specific purposes, Class K is uniquely tailored for the risks associated with cooking oils and fats, making it the correct choice for addressing fires of that nature.