What is the difference between high energy and low energy foam systems in terms of the foam solution?

• A. Water only is used
• B. Foam concentrate is added
• C. Oxygen is added
• D. Compressed air is introduced prior to discharge

Answer: (D)

The key idea is how air gets into the foam mix. In a high-energy system, compressed air is introduced into the foam solution before it leaves the apparatus, which creates a highly expanded foam and delivers it quickly to the fire. In contrast, low-energy systems rely on air being drawn in or entrained at the nozzle rather than being added to the solution beforehand, resulting in less foam expansion.

Remember, foam solution is always made from water and foam concentrate; oxygen isn’t used in forming the foam, and water-only would not produce foam. So the defining difference is the pre-discharge introduction of compressed air.