Which of the following statements about foam application is NOT true?

• A. Aqueous Film Forming Foam can be effectively applied through a standard fog nozzle.
• B. Air aspirating foam nozzles or foam nozzle adaptors on standard fog nozzles produce effective, high quality foam.
• C. Fog nozzles are recommended for use with protein and fluoroprotein foam.
• D. Foam concentrates cannot be used with fog nozzles.

Answer: (C)

Foam effectiveness depends on how air is entrained into the foam concentrate to create a stable, expanding blanket on the fire. Fog nozzles deliver a fine spray, but they don’t reliably introduce enough air into the foam solution to produce the large, stable bubbles required by protein and fluoroprotein foams. Those concentrates need an air-entraining nozzle or a fog nozzle equipped with a foam adaptor that promotes air mixing to achieve the proper expansion and film formation. Without that air entrainment, the foam from a fog nozzle tends to be weak and short-lived, which is why using fog nozzles for protein and fluoroprotein foam is not recommended. The other statements reflect typical practice: certain foams can be used with air-aspirating nozzles or adapters to improve quality, and foam concentrates can be used with fog nozzles when appropriately equipped, though not as ideal as using an air-entraining nozzle.