What has been shown regarding the performance of Class A foams when used with a standard fog nozzle at concentrations over 0.5%?

• A. Significant improvement is noted
• B. Little or no performance improvement is shown
• C. Performance is only effective at 1%
• D. It's ineffective below 0.5%

Answer: (B)

Using Class A foams with a standard fog nozzle at concentrations over 0.5% shows little or no performance improvement. Research has demonstrated that while Class A foams can enhance the extinguishing effectiveness of water, increasing the concentration beyond a certain point does not significantly enhance performance. The optimal performance for these foams generally occurs at lower concentrations, and excess foam can lead to unnecessary waste and complications in application. Therefore, the understanding is that above 0.5%, the advantage gained does not proportionately reflect the increase in concentration, thus leading to the conclusion that little or no performance improvement is achieved at higher concentrations.