A Class K agent's effect on fuel is known as?

A Class K agent's effect on fuel is known as?

• A. Hydration
• B. Oxidation
• C. Saponification
• D. Combustion

Answer: (C)

For Class K fires involving fats and oils, the extinguishing action on the fuel is a chemical reaction called saponification. The alkaline components in the agent react with the fats in the oil to form soap (and glycerin), creating a soapy layer on the surface. This layer cools the fuel, emulsifies the oil, and helps smother the flame by separating the fuel from the air, reducing vapor formation and flame spread. Hydration would introduce water, which is unsafe for grease fires and can cause splattering; oxidation and combustion describe burning processes, not the fuel-altering action used to stop the fire. So the fuel’s effect is to undergo saponification.