Foam is defined as?

• A. A stable aggregation of bubbles of lower density than oil or water.
• B. A chemical concentrate used for firefighting.
• C. A type of sprinkler head.
• D. A mixture of foam and water.

Answer: (A)

Foam is a stable aggregation of gas bubbles dispersed in a continuous liquid phase. In firefighting, those bubbles are gas trapped within a thin liquid film formed from water plus a foam concentrate, making the foam lighter than the surrounding liquid so it can blanket surfaces. The stability comes from surface-active agents in the foam concentrate that lower surface tension and create a film around each bubble. So the best description is a stable collection of bubbles with lower density than the liquids around them. It’s not just the concentrate by itself, not a sprinkler head, and not simply a mixture of foam and water.