In the roll-on foam application, which of the following best describes where the foam is applied?

• A. Directs the foam stream directly onto the flames from above.
• B. Directs the foam stream on the ground near the front edge of the burning liquid pool.
• C. Directs foam to the far edge of the pool.
• D. Directs foam onto the surface of the pool only.

Answer: (B)

The key idea is that roll-on foam creates a protective blanket by starting at the outside edge of the burning liquid and spreading across the surface. In this method, foam concentrate is applied on the ground right at the front edge of the pool, just ahead of the liquid. The foam then blankets the surface and rolls inward, covering the liquid and forming a barrier between fuel and air while cooling the surface. This edge-start approach is what makes the foam blanket effective and prevents vapors from sustaining the fire.

Directing foam onto the flames, or only to the far edge or strictly on the surface without the edge blanket, wouldn’t establish that continuous rolling barrier, which is why those options aren’t as effective for roll-on suppression.