Now let's address your latest post:
No doubt that this works for you, but is simpler and "FF proof" using a selectable fog nozzle 95-250 gpm, you'll ever have all the components at hand, nor you've to thread out and then in a new tip.
Why? Set a target flow and buy a nozzle that will do that. My #1 POC FD selected 200 gpm at 75 psi nozzles. We can underpump to get 160 gpm which is our starting flow, call for more water and go to 200 gpm, or get rid of the combo tip and go to 300 gpm through a 1 1/4 slugtip. The changes in pressure are made at the pump not by dialing the nozzle.
Besides, whats if that day the FF does not have the tip, or the thread is fooled with matter, mud, etc?.
With the slug tip it is ALWAYS on the nozzle and all you haveto do is spin off the combo tip.
Do you fight a lot of structure fires with mud inside the building?
You need 150 gpm?, you only have to put the volume ring in 150, do you need 200 gpm, the same and so on.
Nonsense. If the pump operator is pumping the line to supply you with 150 gpm at 100 psi turning the volume ring to 200 will NOT give you 200 gpm until the pump operator boosts the pressure to overcome the increased friction loss. You will not get 150 gpm simply by turning the volume control ring from 200 to 150 if the pump operator is pumping you for 200 gpm. The nozzle will be over pumped and the nozzle will get a higher pressure and thus a higer nozzle reaction. Your nozzle with the volume control ring still calls for coordination with the pump operator to ensure that the proper pressure is being pumped for the proper flow. Add to the the possibility that the pump operator is pumping one gpm and the nozzle is set for another. Belive me it happens. We used to run Akron Turbojets, one of my favorite nozzles, and they were supposed to be set at 125 and straight stream when on the engine. We found them at 30, 60, 95, 125, and the wrong pattern, all the time. The possibility for error is much higher.