AKKAMAAN
Veteran Member
AkkaMaan...you posted up one of these nomograms/charts that showed that a 3/4" hose and it only makes sense. I mean Prince offers these valves with 3/4" working ports and it specifically states (on Northern's website) that this valve is designed for use with 5" cylinders and up to 16gpm pumps. So I can only believe that there is no harm in using 3/4" pressure line. Are you pulling those nomograms from somewhere online that you could share or is it a scan from a book you own? Thanks for your knowledge.
You gotta pay some attention about these nomograms...some of them shows flows in UK gpm, 1 UK gpm = 1.2 US gpm.....Kuriyama is one of them...If the also show litre/min, then it is easy to figure out if the show UK os US gpm....

You can find these nomogram using Google.....
I have my own little tool .....a spread sheet that calculates the velocity for all different sizes....just enter the flow in US gpm and you got it....
It is recommended to stay below
20 ft/sec in pressure lines
10 ft/sec in return lines
4 ft/sec in suction lines