Hi Jack,
Really depends on which machine your using.
Portables have less flow rate than most T/Ms,
The CFR type of tool I have is one that was cobbled together by a mate I once knew. The valve I have fitted is rated at 500 psi but at times it will blow the rubbers, this could have something to do with the flow rate of my machine though. Normally I run the tool at between 150 and 200 psi