In article ,
"Tom Gardner" wrote:

We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

30 starts an hour has got to be hard on a bunch of things.

I wonder if you might be better off with one of the 4 running a bit
slower on a smaller motor and continuously - ie - 3-4hp - and then use
the other 3 as needed when the draw is larger. Don't know for sure, but
seems more likely to be efficient to have one pumping all the time (or
nearly) than to have it pumping and unloaded and pumping with a bigger
motor.

I am prone to overcomplicate things at times, but a setup where you had
that, and then as that started to be overcome you switched in a 7.5, and
when/if the pair got to pressure you shut down the smaller one and let
the 7.5 carry the larger load, unless/until it was unloaded for a long
period of time, when you'd switch it off and go back to the smaller one
when the pressure dropped again...

Seems like something that a PLC could manage for you most efficiently.

Getting the leaks should help, certainly - that's just money out the
window.

--
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