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Pressure Reducer on Submersable pump?

Discussion in 'Irrigation' started by tomcl, Mar 22, 2006.

  1. tomcl

    tomcl LawnSite Member
    Messages: 43

    Has anyone used pressure reducers on submersable pumps, or do you need a pressure tank--The pump puts out around 125psi?

    Thanks for any help on this
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,246

    You need a pressure tank, even if it's a small one, and you're not supplying a house's water usage. You also need the data on the well installation, along with the make and model of the pump. If you have the performance curve of the pump, or can find it online, you can design a system to match the well-and-pump output.
  3. brookviewlawncare

    brookviewlawncare LawnSite Senior Member
    Messages: 378

    why must he use i pressure tank if system design is correct for pump output why cant he just use a pump start ?
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,246

    Since pump output is on a curve, the OP's description of the pump's performance as "puts out around 125psi" suggests to me that the performance curve isn't known. At least not yet. I sure hope the pump isn't running at 125 psi with poly-pipe for the output. And, if I did have to operate with 125 psi from a well, I'd want the 'shock absorber' effect of a pressure tank, even if all I used was a tiny top-of-the-pump tank you sometimes see on shallow-well jet pumps. The use of a tank also dovetails neatly with a pressure switch.

    The thinking here isn't "what do I need to make it operate" so much as "what do I need in case things malfunction" - a pressure relief valve could also be added to the arrangement, for an additional level of protection.
  5. brookviewlawncare

    brookviewlawncare LawnSite Senior Member
    Messages: 378

    what would be the need for the pressure relif valve if he uses a tank and pressure switch? i agree about the 125 psi and the curve but you would have to be nuts to be design a system on that side of the pump curve
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,246

    I've never seen a pressure-switch-controlled submersible without one, since most of those multi-stage pumps can develop enough pressure to blow their poly drop pipes if they run into a closed valve. Come to think of it, I do remember a submersible pump installation that had no pressure relief valve. It so happened that the pressure switch did fail, and the pump had enough pressure to burst the poly main line of the old sprinkler system it supplied. To the homeowner's distress, the break was underneath the concrete deck of the swimming pool that was put in after the sprinkler system.
  7. brookviewlawncare

    brookviewlawncare LawnSite Senior Member
    Messages: 378

    never new that I have never installed a pressure relif valve on any sub smaller than a 5hp
  8. Critical Care

    Critical Care LawnSite Bronze Member
    Messages: 1,654

    How about using a cycle stop valve?

  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,246

    I always thought that was a lazy-man's method, instead of matching system performance to water supply. With interchangeable rotor nozzles, the matching is pretty simple. Still, the device can have its uses.

    Also, notice the presence of both pressure switch and pressure relief valve in the diagram. For all pumps, a pressure relief is cheap insurance, compared to what it protects.
  10. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Reminds me of the time we were having problems with one of our BIG pumps at one of the high schools. We were standing in the area of the backflow off to the side of the pressure tank when I heard a rumbling sound. I backed up through the gate as the relief valve opened and dumped water all over two other guys. :laugh:

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