konandrew 's List: Fluid Mechanics

  

Home-made Hydraulic Ram Pump

 

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Pump Plans	Assembly Notes	Performance	Links
How It Works	Operation	Test Installation

  

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This information is provided as a service to those wanting to build their own hydraulic ram pump.  The data from our experiences with one of these home-made hydraulic ram pumps is listed in Table 4 near the bottom of this document. The typical cost of fittings for an 1-1/4" pump is currently $120.00 (U.S.A.) regardless of whether galvanized or PVC fittings are used.

  

 
 Click here to see a picture of an assembled ram pump

  

Table 1.  Image Key

                                                                                           

1	1-1/4" valve	10	1/4" pipe cock
2	1-1/4" tee	11	100 psi gauge
3	1-1/4" union	12	1-1/4" x 6" nipple
4	1-1/4" brass swing check valve (picture)	13	4" x 1-1/4" bushing
5	1-1/4" spring check valve	14	4" coupling
6	3/4" tee	15	4" x 24" PR160 PVC pipe
7	3/4" valve	16	4" PVC glue cap
8	3/4" union	17	3/4" x 1/4" bushing
9	1-1/4" x 3/4" bushing

  

All connectors between the fittings are threaded pipe nipples - usually 2" in length or shorter. This pump can be made from PVC fittings or galvanized steel. In either case, it is recommended that the 4" diameter fittings be PVC fittings to conserve weight.

  

Conversion Note: 1" (1 inch) = 2.54 cm; 1 PSI (pound/square inch) = 6.895 KPa or 0.06895 bar; 1 gallon per minute = 3.78 liter per minute. PR160 PVC pipe is PVC pipe rated at 160 psi pressure.

 

Click here to see an image-by-image explanation of how a hydraulic ram  pump works

 

Click here to see a short  mpeg movie of an operating ram pump
 (Note - this is a 6.2 mb movie clip.  On slower systems (11 mbps,  etc.), it will load "piece-meal" the first time.  Allow it to finish  playing in this fashion, then press the play button again to see it in full  motion with no "buffering" stops.  Dial-up users may have to download the  file to see it - simply right-click on the link, then select "Save Target As..."  to save it to your computer.  Downloading may take considerable time if you  are on a slower dial-up system.)

  

Assembly Notes:

  

 

Pressure Chamber - A bicycle or "scooter tire" inner tube is placed inside the pressure chamber  (part 15) as an "air bladder" to prevent water-logging or air-logging. Inflate the tube  until it is "spongy" when squeezed, then insert it in the chamber. It should not  be inflated very tightly, but have some "give" to it.  Note   that water will absorb air over time, so the inner tube is used to help   prevent much of this absorbtion.  You may find it necessary, however,   to drain the ram pump occasionally to allow more air into the chamber.   (The University of Warwick design (link below, pages 12-13) suggests the   use of a "snifter" to allow air to be re-introduced to the ram during   operation.  Their design, however, is substantially different from the   one offered here and provides a location (the branch of a tee) where the   addition of a snifter is logical.  This design does not.  Also,   correctly sizing the snifter valve (or hole as the case may be) can be   problematical and may allow the addition of too much air, resulting in air   in the drive pipe and ceasing of pumping operation.  For these reasons   we have elected not to include one in this design.)

 

According to information provided by the University of Warwick (UK) (    http://www.eng.warwick.ac.uk/dtu/pubs/tr/lift/rptr12/tr12.pdf , page   14), the pressure chamber should have a minimum volume of 20 times the   expected delivery flow per "cycle" of the pump, with 50 times the expected   delivery being a better selection.  The chart below provides some   recommended minimum pressure chamber sizes based on 50 times the expected   delivery flow per "cycle."  Note that larger pressure chambers will   have not have any negative impact on the pump performance (other than   perhaps requiring a little more time to initially start the pump).    Some of the lengths indicated are quite excessive, so you may prefer to use   two or three pipes connected together in parallel to provide the required   pressure chamber volume.  Well pump pressure tanks will also work well   - just make sure they have at least the minimum volume required.