What should be used to extinguish a Class B fire?

To effectively extinguish a Class B fire, which involves flammable liquids and gases, the use of specialized agents is critical. AFFF (Aqueous Film Forming Foam) fire extinguishers and chemical powder extinguishers are both suitable for managing Class B fires due to their ability to smother and suppress the fire.

AFFF extinguishers create a barrier between the fuel and the oxygen, thus preventing the fire from spreading. This is particularly effective for liquid fires since AFFF can float on top of the liquid and form a film that suppresses vapor emissions and cools the surface.

Chemical powder extinguishers, on the other hand, work by interrupting the chemical reaction of the fire. The powder can smother the flames and is often formulated to be effective against a range of flammable liquids.

Using both types of extinguishers provides versatility and enhances the chance of effectively putting out a Class B fire, which is why selecting both AFFF and chemical powder as extinguishing agents is the correct answer.