AFFF extinguishing agents are primarily used for which classes of fires?

Aqueous Film Forming Foam (AFFF) extinguishing agents are designed primarily for use on Class B fires, which involve flammable liquids such as gasoline, oil, and other hydrocarbons. However, AFFF can also provide effective firefighting capabilities on Class A fires, which involve ordinary combustibles such as wood, paper, and textiles.

The unique properties of AFFF allow it to suppress both classes of fires effectively. For Class B fires, the foam creates a barrier on the surface of the flammable liquid, which helps prevent the vapors from igniting. In the case of Class A fires, AFFF not only cools the burning material but also forms a film that enhances water's effectiveness in soaking and penetrating the material.

While the question presents options that involve combinations of fire classes, AFFF's versatility in addressing both Class A and Class B fires makes this the most appropriate response. It is important to note that AFFF is not suitable for Class C fires, which involve live electrical equipment, or Class D fires, which involve combustible metals, due to the different demands and safety protocols required for those specific situations. This further reinforces the significance of selecting Class A and B as the primary areas where AFFF is effectively utilized.