EvMiBo
VictoriaConcordiaCrescit
IMO a non pressure pump gets good results, if you need to turn down the incoming air with a needle valve whats the use of going with a pressure pump ( the reason of going with a pressure pump is to draw more air)
If you're getting ideal air flow [which seems to be 20-22 SCFH I think] by choking it down with a needle valve at lower flow rates are you therefore getting longer contact time? In theory (for me anyway) you are, and that's why a pressure rated pump is more favorable. Or am I off?