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Is there a compact device which can trade flow rate for lift height without too many moving parts?

My particular application is a 10 meter deep and 10 centimeter wide well with shallow water level, therefore the usual high-powered well pumps run dry too quickly. Submersible pumps with low flow rate, high working lifetime and sufficient pressure do not seem to exist. But even if such pumps did exist, I would still be interested in an answer from an academic point of view. Maybe there is a solution without any moving parts at all? That would be neat!

Ideas I discarded so far:

  • A hydraulic ram pump seems to requires a high flow rate and long feed lines.

  • Daisy-chaining multiple small pumps with low pressure multiplies failure rate. (I tried five pumps of type AD20P-1230D with a head of 2 meter each, but the rated 50,000 hours lifetime is highly optimistic.)

  • A water wheel driving a chain pump sounds like a maintenance nightmare due to the mechanical nature of the chain pump and it is also not very compact (disregard the cow in the following illustration).

water wheel and chain pump

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    $\begingroup$ Has moving parts: an Archimedes screw. $\endgroup$
    – Solar Mike
    Feb 7, 2021 at 8:54
  • $\begingroup$ what is the exact height you need to lift the water? 10 m is too much to have suction pumpe outside the well, but when the water level is 7-8m below grade it just might work and allows more flexibility, as the pump doesnt have to fit down the well. $\endgroup$
    – mart
    Feb 8, 2021 at 16:04
  • $\begingroup$ fao.org/3/ah810e/AH810E06.htm has some ideas, but at a quick google I didnt find anyone seeling the positive displacement well pumps. How much flow rate do you need? $\endgroup$
    – mart
    Feb 8, 2021 at 16:19
  • $\begingroup$ also is it feasible to make the well larger (bore diameter), then you are more flexible in pump choice and can pick any sump pump. $\endgroup$
    – mart
    Feb 9, 2021 at 7:12
  • $\begingroup$ All you are looking for is a low flow high pressure pump. There are thousands of variations. You just can't find one under the "well pump" category. You could also just throttle the outlet. $\endgroup$
    – Tiger Guy
    Feb 9, 2021 at 21:54

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Here's a crackpot idea: Positive displacement pump with compressed air as the piston. I've seen these documented somwhere on the internet, and they are a common trade fair gimmick to show off check valves.

The basic idea is:

  • water flows freely into container through check valve (as large as fits)
  • pressurized air is pumped into container, water is pushed out through a pipe near the low end (and another checkvalve, probably DN15 or DN25 or so)
  • when water is pumped out, the air is allowed to escape from the container and water re-enters

The container can be a piece of pipe, DN80 or so. The tricky part is to actutate the compressed air - I've seen a device with two swimmers (again, don't know where anymore) that could fit down a narrow hole. With off the shelf components, probably two electic level switches and solenoid valve like you would use for a single acting pneumatic cylinder. when using flexible tubing for air and water, it should be easy to lift the whole device from the well.

Big downsides:

  • efficiency! compressed air is a rather expensive form of energy. You'd want a air supply with 1 bar + enough to overcome flow resistance, anything more is wasted energy. Even then total efficiency will be lower than a normal pump

  • it's a somewhat experimental project, not a tried and tested solution

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  • $\begingroup$ This is indeed a crazy, but also ingenious idea! It might be possible to increase efficiency by venting the emptied container back into the air compressor (if the compressor can handle wet air - most are probably not too happy with that). $\endgroup$
    – 983
    Feb 20, 2021 at 12:35

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