W + Conc (=Sol) + A + A = Foam (Foam is Bubbles and Bubbles is Water)
The Air is fairly simple.
When making NAF, atmospheric air is pulled into the Solution (W+Conc) at the aspirating nozzle.
For CAF, a high pressure system, typically a compressor, adds the air just after the Solution Discharge Valve and just prior to entering the fire hose.
There are different types of compressors and different methods used to power compressors. Some compressors have involved cooling systems (as compression generates heat). See Compressors – {Link coming soon}. In this section, it is only important to know that the operator should become very familiar with the system on the engine.
