How does Class K extinguishing differ from Class B/B:C extinguishers?

• A. Class K uses wet chemical to saponify fats, specifically for cooking oils, while Class B/B:C extinguishers use other agents for flammable liquids or electrical fires.
• B. Class K uses dry chemical to absorb oil; Class B uses water.
• C. Class K works on electrical panels; Class B does not.
• D. Class K is for metal fires; B/C are for cooking oils.

Answer: (A)

The key idea is the extinguishing method and the fires they’re designed for. Class K uses a wet chemical agent that saponifies fats in cooking oils. When this agent meets the oil, it converts the fat into a soapy layer that cools the oil and forms a barrier on the surface, smothering the flame and preventing reignition. This specialized approach is specifically for kitchen oil fires.

Class B and B:C extinguishers use different agents (like dry chemical, foam, or CO2) designed for flammable liquids and, in the B:C case, energized electrical fires. They don’t saponify fats and aren’t intended for cooking-oil fires. Using water-based or inappropriate agents on oil fires can spread the oil and worsen the fire.

So, the distinguishing point is the wet-chemical saponification mechanism for cooking-oil fires versus the other extinguishing methods used for flammable liquids and electrical fires.