help with system

Discussion in 'Irrigation / Sprinkler Forum' started by cameron, Jun 12, 2008.

  1. cameron

    cameron New Member

    Messages:
    16
    I am currently running 3/4 hp submercible pump 500 ft of 1in pipe at 50 ft elevation rise above water, getting at the end about 14 gallons a minute. I can run 2 of my impact sprinklers large type rated to reach 100 ft diameter, my question is I have a 1hp jet pump rated at 22 gallon per minute. Can this be used as a booster pump or will it suck the submersible dry, I hooked up the jet at water source about 5ft above water but had very little water at top of the hill 500 ft. so I removed it should this have worked here or not. What suggestion do you have to get the most of what I have.
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,418
    Location:
    Lubbock, Texas
    You can use the jet pump to boost pressure as long as you are using less than 14 GPM. You still can't get more water than the sub will deliver. The jet pump by itself won't deliver as much pressure as the sub.
  3. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    There have been installations of large tank(s) in basements (of large homes) that were filled by a low-flow deep well, and a jet-pump atop the tank draws water and delivers higher flow into a lawn sprinkler system. What elevations are there on this property? How large is the property?
  4. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    If you put the jet pump on the discharge of the submersible it will cause the submersible to deliver more flow because it will be working against less pressure. Proper design of such a system should be based on knowledge of the pump GPM/head characteristic and the depth to water in the well.

    You want to be sure that you don't operate the submersible beyond its range or you could overload it with too much flow.

    Get the pump curve (or post the make and model number of the pump) so we can see the maximum rated flow for the pump. That maximum rated flow, often about 150% of the nameplate rating of the submersible pump, is the maximum that you should take out of the submersible.

    As long as you don't exceed the GPM limit of the pump, the submersible/jet system will operate an a point where you will get increased flow at the same pressure or increased pressure at the same flow.

    NOW TO THE RISKS!!!
    If the flow is shut off or restricted you will probably blow up the jet pump!

    Submersibles have a nasty characteristic of VERY HIGH PRESSURE when the flow is restricted. Add that to the boost from the jet pump and it will almost certainly fail the jet pump or the lines on the discharge of the jet pump, whichever is weakest.

    You should have a relief valve on such a system that will discharge enough flow so the submersible will never approach shutoff pressure (less than 25% to 50%of it's flow rating).
  5. valveman

    valveman Moderator Staff Member

    Messages:
    4,418
    Location:
    Lubbock, Texas
    I have done this many times. If you restrict the output of the jet pump with a valve of any kind, you will have the combined shut off head of the submersible and the jet pump. The only problem I have ever had is if the seal or volute gasket in the jet pump is not rated for that much pressure. If you never restrict the pump, you don't have this problem.
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