With a foam solution, which nozzle type is used to produce a low expansion, short-lasting foam?

• A. A mechanical blower
• B. A solid bore nozzle
• C. A water-aspirating foam
• D. An adjustable fog

Answer: (D)

Controlling how much air gets into the foam solution determines how much the foam expands. An adjustable fog nozzle lets you dial in the pattern and the amount of air that mixes with the foam. For low expansion and foam that doesn’t last long, you set the nozzle to a tighter pattern with minimal air entrainment, which keeps the expansion small and the foam short-lived. Other options tend to force more air into the mix or don’t offer the same adjustable control over air entrainment, leading to higher expansion foams or less predictable performance.