Compressed air foam system

A compressed air foam system is used in firefighting to deliver fire retardant foam for the purpose of extinguishing a fire or protecting unburned areas. Typical components include a water source, a centrifugal pump, foam concentrate tanks, a direct-injection foam proportioning system on the discharge side of the pump, a mixing chamber or device, a rotary air compressor, and control systems to ensure the correct mixes of concentrate, water, and air.

Source: Wikipedia — Compressed air foam system (CC BY-SA 4.0)