W + Conc (=Sol) + A + A = Foam (Foam is bubbles and Bubbles is Water)
Agitation is nothing more than scrubbing the Solution Air mixture to generate the bubbles.
In NAF – The agitation occurs in the aspirating nozzle just prior to the foam discharge. The nozzle usually has some type of obstruction method in the nozzle that agitates the mix. For example, it might be a series of screws or a screen or net over the end opening of the nozzle. {Photo examples coming soon!}
Agitation in CAF occurs in the fire hose. What most firefighters understand as friction loss from the hose, now becomes a more useful agitation of the Solution/Air mixture to form the Bubbles.
Agitation is necessary to get the Solution (W + Conc) and Air to thoroughly mix and stirred to form the bubbles. Without adequate agitation, only separate Solution and Air would escape the end of the nozzle.
While a fog nozzle seems like it would make a good agitator, when flowing CAF, the Foam, already mixed and agitated, flows into the nozzle which then pops the Bubbles. This is evident by the discharge sound from the nozzle – Solution + a loud rush of escaping Air already freed from the Bubbles. No Bubbles will flow from the nozzle, only drops. See CAF Nozzles.
