Which of the following is NOT a recognized class of foam according to NFPA 403?

• A. AR-AFFF
• B. AFFF
• C. Fluoroprotein foam
• D. PCA foam

Answer: (D)

PCA foam is not recognized as a class of foam according to NFPA 403, which sets standards for fire protection services—specifically for airport firefighting operations. The relevant classes of foam specified in NFPA 403 include AR-AFFF (Alcohol-Resistant Aqueous Film Forming Foam), which is designed to fight flammable liquid fires, AFFF (Aqueous Film Forming Foam), and fluoroprotein foam, which contains protein and fluorinated surfactants for enhanced fire suppression capabilities.

These recognized types of foam are integral to firefighting strategies in the aviation sector, particularly because they can effectively address the unique challenges posed by aircraft fires. In contrast, PCA foam does not have the same level of recognition or application in the standards established by NFPA 403, and as such, it is not considered a standard class of firefighting foam within this framework.