Cooperative Personnel Services Firefighter (CPS) Practice Exam

Class K fires involve combustible cooking media, such as oils and fats, which are commonly found in kitchens, particularly in commercial settings. The most effective type of extinguisher for these fires is the wet chemical extinguisher.

Wet chemical extinguishers contain a specialized agent that can effectively cool the fire and create a barrier between the heat source and the fuel. When discharged, the wet chemical agent reacts with the cooking oils and fats, forming a thick foam that helps to suppress the flames and prevent re-ignition. This specific mechanism makes wet chemical extinguishers particularly suited for handling the unique challenges posed by Class K fires, as they target the type of fuel involved and provide an effective means to extinguish the fire safely.

Using other types of extinguishers, such as dry chemical or carbon dioxide, may not address the specific combustion properties of cooking oils and could, in some cases, fail to adequately suppress or could even spread the fire due to the wrong method of suppression. Thus, the wet chemical extinguisher is recognized as the standard and safest option for Class K fire situations.