What type of combustibles does "Class A" foam extinguish?

"Class A" foam is specifically designed to extinguish ordinary combustibles, which include materials such as wood, paper, cloth, and some types of plastics. This type of foam creates a blanket that cools the burning material and suppresses vapor release, effectively suffocating the fire. The foaming agent in Class A foam aids in the reduction of surface tension of water, allowing it to penetrate deeply into burning materials and enhances its cooling capabilities.

The other types of combustibles are not suitable for Class A foam. For instance, electronics and flammable liquids might require specialized foams or extinguishing agents, while natural gas and propane fires require extinguishing methods that can effectively handle gas fires, which are significantly different from the behavior of solid materials. Similarly, electrical fires and metal fires necessitate specific approaches due to the nature of the materials involved, with carefully managed agents to prevent further risk. Therefore, Class A foam's primary focus is on ordinary combustibles.