PVC Maximum Flow Rate?

[mas985]

Just a word of caution. Some pump manufactures will simply change out the impeller of a 3/4 HP pump to 1/2 HP impeller but use the same 3/4 HP motor. The result is an under loaded motor which fairly inefficient. You can this is the case when the maximum current draw is the same for a 1/2 HP and 3/4 HP pump.

It sounds as though you have about 50 feet of head with your current pump. However, the head loss will change with a new pump depending on if the new pump has a higher or lower brakiing HP (BHP). A fairly good approximation for the head loss change is:

Head Loss New Pump = Head Loss Old Pump * (BHP(New)/BHP(Old))^2/3

[catnip]

Mark, thanks for the caution about the impeller vs. HP possibility. I checked that on the Sta-Rite Max-E-Pro line and there were both different impellers and different motors with different current draws for their 1/2 and 3/4 HP models.

I also appreciate the dynamic head loss vs. HP equation. I presumed there had to be some kind of change with HP since the term is "dynamic" after all!