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Originally Posted by MaxxxRacer
... it could pump much much furter.. but stil there is a point when the resistance of the water in the tube will cuase the pump to stop flowing even if the tubing is horizontal. this is just because the water would be so heavy that the pump could not start moving it.
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??
If the tubing is horizontal, the resistance is from friction. Friction goes up as velocity goes up (so it also goes up as tubing diameter goes down). It's a bit complicated because there's an interplay between laminar effects and eddy flow. I don't claim to understand that part particularly well.
However, the weight of the water
doesn't come into it, except in the sense of inertia, which is an issue with flow start and stop. This is not intermittent flow so we are
not dealing with start and stop.
Here's a thought experiment (well, you can do it, if you like).
Take two 100' lengths of horizontal pipe. One has 1/32" ID, the other one 1" ID. The water in the pipe weighs more in the 1" ID pipe. (calculating weight of water in each pipe left as an exercise for the student).
Start out with the water pressure at one end exactly the same for both sizes of tubing. You can do this with an essentially unlimited size reservoir with water level a set distance above the pipe, a pump, whatever - and put a measuring bucket at the far end. Let the water run until the output at the far end reaches a steady rate, whatever that rate might be.
OK: So now you're saying that there will be more flow into that bucket with the 1/32" ID tubing, because the cylinder of water being moved is lighter than the one in the 1" pipe.
Really?