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Water Pump Selection

  1. May 14, 2012 #1
    I need to select a pump that will remove all the salt water from the inside of a hollow driven pile. The pile 1500mm diameter and is 30m in length probably containing around 20m sea water.
    does anyone have any ideas on how i go about choosing the right pump for the job?
    I have no experience with pumps so any help at all would be apprectiated.
  2. jcsd
  3. May 14, 2012 #2


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    Gold Member

    Hi, Bert;
    Unfortunately, I know just about nothing in regard to this subject. It does seem to me, however, that more information would be helpful.
    Is this a one-time deal, or a continuous operation? What sort of drive mechanism do you have in mind (electric of what wattage, gas, diesel, goats on a treadmill...)?
    Does the term "salt water" mean raw seawater, or something with even higher salinity? That might make a difference when choosing materials for your equipment.
    How far, and at what angle, do you have to move the efflux?
    There are more considerations, but this is just a bit of a "heads up" to get you prepped.
  4. May 14, 2012 #3
    I'd google salvage pump manufacturers and talk to their technical sales people
  5. May 14, 2012 #4
    I would guess that you have over 1000 cubic feet (7500 U.S. gallons) of water in the pile, and because of its depth, you will have to lower an electric pump down into the pile. The pump has to be roughly 5 meters or less above the water surface. The pump could be operated either off the local utility, or off an alternator. So if you pumped 7.5 gpm, it would take ~100 hours. What is your timescale?
  6. May 14, 2012 #5
    Some more info,
    We are going to have to do this over and over, thesea water in the pile needs to be pumped vertically up the pile and out into the water.
    We will be using a submersible pump, we can supply power from a generator we have nearby.
    I suppose what I need to know is what calculations do I have to do to chose the right pump (ie a big enough one 10kW, 5 kW etc)
    When I calculate the pressure head how do i know that my chosen pump will be able to perform the task effectively a number of times.
  7. May 14, 2012 #6


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    look up "sump pump". Not sure whether they have any problem w/ salt water.
  8. May 14, 2012 #7
    Here is a very crude estimate of the power required to pump 10 gpm (gallons per minute) up 30 meters (worst case).
    Assume 60% pump electrical to mechanical efficiency
    Assume pump 60% hydraulic efficiency
    10 gallons = 38 kg
    W =38 x 30 x 9.81/(0.6 x 0.6) = 31,000 joules per minute = 520 watts

    You can scale from this.
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