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Pump system Fail Guards

Discussion in 'Professional Discussions' started by ArTurf, Jun 25, 2020.

  1. ArTurf

    ArTurf LawnSite Fanatic
    Male, from Ark
    Messages: 6,760

    For systems that use an on demand pump, no pressure tank or regulating devices what are some simple ways to avoid damage in the event a valve doesn't open beyond the simple pressure relief valve? I know a flow meter with auto shutdown would work but let's say it's not practical to incorporate in an existing system.
     
  2. Sprinkus

    Sprinkus LawnSite Silver Member
    Messages: 2,512

    For pumps up to 3HP a Munro Smartbox with thermal protection would be a fairly simple, yet professional option.

    An even simpler device could be a pressure switch wired in series with the pump start circuit. Set the pressure switch cut-off high enough to not shut down the pump during proper operation but shut it off if the pressure gets high enough, as in a deadhead condition.

    For large pumps a simple "Murphy" switch system can be wired into the magnetic starter circuit to shut down the pump in the event of an under pressure or over pressure condition.

    Of course a properly installed and programmed VFD can protect against deadhead, dry run, and many other issues that affect pumps.
     
    RhettMan likes this.
  3. Sprinkus

    Sprinkus LawnSite Silver Member
    Messages: 2,512

  4. RhettMan

    RhettMan LawnSite Gold Member
    from Texas
    Messages: 3,121

    Thanks Sprink
     
  5. RhettMan

    RhettMan LawnSite Gold Member
    from Texas
    Messages: 3,121

    do guages fail often?
    The other day:

    I gauged 20 psi dynamic on a 10GPM system at a "garden hose-bib" 20 ft from tank, while distant zone in operation, at the moment that the pump was turning off and the gauge between pump and tank read 70 psi.

    In the end, it appear someone had adjusted the pressure switch stops in synchronicity with the pump to tank gauge.

    A new gauge read alot different than old gauge.
    Iv had a bib gauge fail on me before, and its embarrassing when it happens.

    Are there "primo gauges" ?
     
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 53,005

  7. Sprinkus

    Sprinkus LawnSite Silver Member
    Messages: 2,512

    I've been using the liquid-filled Merrill gauges, sold by our local "horned" irrigation supply house, with good success.
     
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 53,005

    One thing not covered in detail, maybe because it's a bit complicated, is that a standard pressure relief valve is not easy to apply to a straight centrifugal pump, on account of the opening of that relief valve happens gradually as the pressure rises. In order to be fully open at 50 psi, it might have to be partially open at 40 psi. This spread introduces some difficulty dialing in a compromise setting on the relief valve.
     

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