Which is the correct nozzle to use with medium-expansion foam?

The appropriate nozzle to use with medium-expansion foam is an air-aspirating nozzle. This type of nozzle is specifically designed to introduce air into the foam solution, allowing for the formation of larger foam bubbles which are crucial for effective extinguishment. Medium-expansion foam aims to create a blanket over flammable liquids, cutting off oxygen and helping to cool the fire.

Air-aspirating nozzles operate by drawing air into the foam solution stream, which enhances the expansion and stability of the foam blanket during firefighting operations. This results in better coverage and improved fire suppression capabilities against flammable liquids.

In contrast, other nozzle types such as adjustable fog and water-proportioning nozzles do not have the same capacity to generate foam expansion. A water-aspirating nozzle may provide some expansion but is not as effective as air-aspirating nozzles in creating medium-expansion foam specifically designed for flammable liquid hazards.