Ive been lurking for about a year I planned and built a pond useing
this group as my main resource thank you.
I went through a gorman-rupp pump class at work, great pumps, but much
too expensive for me. Anyway I learned a little.It was mostly about
rebuilding their pumps but there was some troubleshooting. They had a
pump setup with a clear suction pipe.They varied the inlet with a
valve to show the effects of suction head. When increasing suction
head bubbles formed in the suction pipe. They werent bubbles but steam
pockets formed by the vacuum pulled on the inlet and the G-R guys said
it will pit impellers .Also they had an ammeter on the power and
increased suction head increased amps by more than double .
The G-R guys varied the output and the pump banged. They said this
causes clean straight brakes in the impeller shaft. We use these pumps
to spray waste water and we break shafts often .The bang was hard to
detect but was there.We increased orfice size, no broken shafts so
far.
This class helped me at home because I have a clear primeing pot on my
home bluegill pond pump and had steam pockets. I redone my strainer
and got rid of the steam pockets the pump runs quiter, cheaper and
smoother and I hope has a long life. I hope this helps someone
somewhere. Ive read all this before but seeing it demonstrated made me
believe it.