pumping water with compressed air

Discussion in 'Shop Talk' started by Ed Norman, Nov 2, 2004.

  1. Ed Norman

    Ed Norman Well-Known Member

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    Next year I will have a windmill compressing air to get water from our well with the air-lift method. It will pump into a big holding tank. Then we will irrigate with it. Some can be used for flood or drip irrigation. No problem. But to get some pressurized to run a sprinkler is trickier. I'll have the big tank of compressed air. How can I use that? I had first thought of a small 12VDC solar pump and battery and panel, but the compressed air is right there waiting. Any thoughts? I have alot of ideas, but want to see what someone else thinks up.
     
  2. agmantoo

    agmantoo agmantoo Supporter

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  3. herefordman

    herefordman Well-Known Member

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    Agmantoo is right,
    Diaphragm pumps run off air and work extremely well, there are lots of manufacturers out there, Monarch is a good one as well, you can get them in plastic or Stainless, or whatever your choice.
     
  4. insanity

    insanity Well-Known Member

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    If your holding tank is big enough and or elevated (it doesn't take much of either!).You could plumb out of the bottom of it and use its pressure plus gravity to build up some un real water pressure.I once read an article about starting out with like 4inch pipe then reducing it down as it went along.At the end the size was less than 1/2 with some un-believable pressure. :eek:
    Id think that would be your cheapest,easiest way to go.Keeping the water toped off by the wind mill would also keep pressure constant.More pressure than volume would make it possible for the wind mill to keep up with the flow rate.Like a pressure washer.

    Not sure what you call this type method (gravity flow maybe?) but id look into it. ;)
     
  5. Ed Norman

    Ed Norman Well-Known Member

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    All very good ideas. The diaphragm pumps, especially the cheap ones, look great. I had also thought about using the pressure of the storage tank volume, but didn't know how much pressure I would get. I know when you pull the plug on a big tank, lots of water comes out fast.

    The land is flat. Many years ago it was flood irrigated alfalfa, but now it is bare. It is great soil, but years of drought have killed everything. And I can't see which way the ground slopes for flooding. I'm not sure how to tell.

    I got an old book on building an Arusha Windmill, a cheap way to pump water. They have a diaphragm pump in there, built from a 13" car tire. Screw a metal plate on each side to plug the holes. The bottom plate has two check valves to let water in and out. Set it in water, pull up on the top plate then release. Tire fills and empties. It showed a picture of one in use and water was flying out the outlet tube.
     
  6. insanity

    insanity Well-Known Member

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    I did some searching and finally found a short article/answer.For a tank ten ft off the ground you would get 4.3 pounds per square inch of water pressure,measured from the drain on the tank to the ground.For every ten ft of elevation add another 4.3 PSI.I'm thinking they measured that wrong.The higher the water level in the tank the more pressure at the drain already,correct? I figure you'd be closer measuring from the top of your water level in the tank to the ground..Anyway that gives you some idea of pressure, should you want to go that way.

    To tell which way the ground slops.You might try pulling a string out 20 or more ft.Drive two rods in the ground and tie the string tight between,and at an equal distance up the from the ground on each end.Hang a string line level on it or try holding regular level to it.You could possibly pull out ft or more string tight enough to hold the string level.Have some one pull one end up until level so you can see how much fall/tilt you have.
     
  7. mikell

    mikell Well-Known Member

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    1 PSI = 27.7" of water. Thats why water towers are soooo talllll. 50 PSI = about 115'


    mikell
     
  8. moopups

    moopups In Remembrance

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    Is the holding tank air tight? If so just put compressed air on top of the water.
     
  9. wtimmons

    wtimmons New Member

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    how much air is needed to pump water up10 ft? will one gallon of air atl 10 psi pump up one gallon of water up 10 ft? does anyone know how to calculate water flow rate?
     
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  10. moopups

    moopups In Remembrance

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    I can calculate this exactly if you can provide me with water hardness, type of pipe (different frictions) and diameter of pipe. My Ace Hardware pocket referance booklet gives 25 pages of this type info.
     
  11. joan from zone six

    joan from zone six Well-Known Member

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    isn't there a method of using compressed air without a pump? i seem to remember a magazine article about piping compressed air to the bottom of a well and letting air bubble up through the discharge line, carrying water along with the rising bubbles - the discharge pipe can terminate in a tank much higher than heighth of points of use and higher than the well-head - one of the points the mag article bragged about was that the compressor could be situated just about anywhere and piping compressed air to the well-head was a piece of cake -
     
  12. John Hill

    John Hill Grand Master

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    There are a couple of ways of lifting water with compressed air.

    A venturi can be useful especially if there is grit or rubbish mixed with the water. Some boat systems use venturi systems for keeping the bilge dry.

    It is easy to lift water from a shallow well with compressed air. Consider a well casing sunk 60' down that has a static water level of (for example) 40'. Now if compressed air can be introduced into the water near the bottom of the casing instead of having a 40' column of water you will have a column of water mixed with air, obviously this weighs less than water alone and with enough air the column will be light enough to reach the surface.

    No doubt there are other ways too.
     
  13. wtimmons

    wtimmons New Member

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    How would you calculate the upward flow of water in a 1.5 " pipe , 15 ft high at two different tank pressure levels, say 10psi and 15psi?

    Thanks for your help!