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How do I size a hydraulic motor to fit a 12 propeller to move water?

by skuhler
Tags: hydraulic motor, water pump
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Feb28-13, 10:44 AM
P: 3
I have a 35 HP diesel motor direct driving a hydraulic pump producing 16 GPM at 2000 psi. The hydraulic pump would be connected with hoses to a water pump inserted in a pipe.

I want to design/build a water pump using a 12" or larger propellor attached to a hydraulic motor inserted in a tube. This pump would be attached to a larger smooth bore pipe inserted in an earthen levee, pushing against a varying total dynamic head from 1 foot up to 18 feet.

I see many hydraulic motors for sale at that describes the motors based on displacement. What is the largest motor I can put in this design to move the greatest amount of water in the shortest period of time?

I'm not an engineer or a physicist, just a man with a plan! Thanks in advance for your help.

Steve K
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Feb28-13, 04:06 PM
P: 35
Hi Steve,
Surplus will have better prices than Grainger. The only reservation I have about this plan is the fact that every time you change power from one form into another yoiu lose efficiency.

"pushing against a varying total dynamic head from 1 foot up to 18 feet. "

Pertinent question: Are you pumping water through your pipe into the bottom of this reservoir through a check valve?
I hope to have some time to do a little calculating this evening.
Feb28-13, 04:34 PM
P: 3
Thanks for your speedy reply. Here's the scenario; I want to pump water that accumulates inside the levee structure into the river, when the flap gate to the tube is shut because of rising water. As the river rises, when it gets about 2 feet over the tube it closes and the gravity drainage is stopped. The river can continue to rise up to 18 feet over the tube. At 19 feet over the tube, the levee is overtopped and drainage is not necessary, you might say!

Feb28-13, 04:44 PM
P: 3
How do I size a hydraulic motor to fit a 12 propeller to move water?

Also, thanks for the tip on Surplus Center, I'll check that out. I'm looking at a motor that uses 11.9 cu in/revolution, max pressure 3000 psi, max rpm 477, with a shaft size of 1.25 in. diameter. According to my calculations, producing 16 gpm should get me about 300 revolutions a minute. Now, I know that the pitch on the blades can vary, is it possible to use a standard prop off a large boat to move the water, and how much water is moved per revolution of the prop?

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