Question 28 QMED02 - Electrician-Refrigerating Engineer

The Correct Answer is B. Aqueous Film Forming Foam (AFFF) is a synthetic firefighting foam designed specifically for extinguishing Class B fires (flammable liquids and gases), particularly hydrocarbon fuels like gasoline, diesel, and oil. AFFF works by rapidly spreading an aqueous film over the fuel surface, which suppresses flammable vapor release and cools the liquid. Engine room bilges are areas where leaking oils and fuels often collect, making them highly susceptible to deep-seated Class B fires. AFFF’s ability to flow across the fuel surface and establish a vapor-sealing film makes it exceptionally suitable for fighting such liquid fuel fires in enclosed or confined spaces. **Why the other options are incorrect:** * **A) any class D fire:** Class D fires involve combustible metals (e.g., magnesium, titanium). These fires require specialized dry powder extinguishers (like sodium chloride or graphite-based powders) that do not react with the metal. Applying AFFF or water to a Class D fire can exacerbate it, cause violent reactions, or spread molten metal. * **C) class C fires in paint lockers:** Class C fires involve energized electrical equipment. While a paint locker (which contains Class A and Class B combustibles) might also contain electrical equipment, the defining characteristic of a Class C fire is the presence of electricity. AFFF is generally conductive, meaning it should not be used on energized electrical fires unless explicitly rated for such use (and even then, it is better to use CO2 or dry chemical). Furthermore, AFFF's primary strength is tackling Class B, not Class C. * **D) all of the above:** Since AFFF is unsuitable for Class D fires (A) and is not the primary agent for Class C fires (C), this option is incorrect. AFFF is specifically suitable for hydrocarbon liquid fires (Class B).