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High GPM Pump Installers

Discussion in 'Irrigation' started by SPEEDSKI, Sep 23, 2011.

  1. txgrassguy

    txgrassguy LawnSite Gold Member
    Messages: 3,083

    Ski, you don't need a cycle stop valve - what you need is a VFD controller and motor.
    No reason to replace the pump end as long as it is still operating with-in the performance curve.
    You are going to have to hill-billy the section wiring by identifying total gpm per zones that are similar then slave those to the controller to operate near the rated capacity of the pump.
    Place a rather large pressure relief valve on the mainline adjacent to the water edge to dump the excess volume back into the water source.

    Any way you look at the pump being set up for the "all or nothing start" to use your phrase, volume differential per section is going to seriously shorten the pump and motor usable life unless you do something to address the discrepancies.

    The good thing about the VFD controllers are they have come way down in price. However, I have no idea what a 10hp controller and motor would cost but since you are stuck with correctly repairing what those hacks installed - you are stuck with a real maintenance headache unless you do something.

    Personally, the hill-billy set-up is the absolute last thing I would suggest.

    Price out the VFD controller and motor as well as the new pressure relief valve making sure the operating threshold is correct for your application (remember not all PRV's fit all applications) and inform the client accordingly. The good thing with the VFD is you usually will not require a PRV as long as the VFD is programmed for all 177 sections.

    Regarding the PRV, if you go this route, make sure you have one that has: 1 - sufficient volume to handle excessive water when the smaller capacity section(s) operate (meaning the overflow discharge is at least three inches otherwise you'll have sharp pressure spikes causing shortened pipe/system components); 2 - has the ability to regulate the pressure without "fluttering" which is what happens when a pressure valve has the set-valve opened essentially all the way particularly when the PRV has the wrong operating pressure threshold.
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,579

    What about using some specialty valves? Maybe a Cla-Val PRV and relief could work.

    What if the pump was operated by way of the flow sensor? And maybe a pressure tank added as a "shock absorber"
  3. stebs

    stebs LawnSite Senior Member
    Messages: 498

    Ditto, although base it off pressure...

    Get yourself one of these (minus the spider of course :laugh: )....

    System runs off pressure and has a Cla valve relief valve to handle excess pressure when zones shut down while the pumps throttle back.
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,579

    If a VFD isn't in the picture, a Cla-Val PRV would do the same thing as a Cycle-Stop Valve. There had to be workable combinations of valves and sensors/switches in common practice, before the VFD's of today.

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