How a Hydraulic Ram Pump works
Here's how the hydraulic ram pump actually works, step-by-step:
(4) At some point this pressure (green arrows) becomes low enough that the flapper in the waste valve (#4) falls back down, opening the waste valve again. (Click here to see an actual image of a ram pump for this step.)
(5) Most of the water hammer high pressure shock wave (red arrows) will release at the drive pipe inlet, which is open to the source water body. Some small portion may travel back down the drive pipe, but in any case after the shock wave has released, pressure begins to build again at the waste valve (#4) simply due to the elevation of the source water above the ram, and water begins to flow toward the hydraulic ram again.
(6) Water begins to flow out of the waste valve (#4), and the process starts over once again.
Steps 1 through 6 describe in layman's terms a complete cycle of a hydraulic ram pump. Pressure wave theory will explain the technical details of why a hydraulic ram pump works, but we only need to know it works. (One American company has been manufacturing and selling hydraulic rams since the 1880ís). The ram pump will usually go through this cycle about once a second, perhaps somewhat more quickly or more slowly depending on the installation.
Each "pulse" or cycle pushes a little more pressure into the pressure chamber. If the outlet valve is left shut, the ram will build up to some maximum pressure (called shutoff head on pumps) and stop working.
The ram is
quite inefficient. Usually 8
gallons of water must pass through the waste valve for each 1 gallon of
water pumped by the ram. That is
acceptable for a creek or river situation, but may not be a good option
for a pond that does not have a good spring flow.
(Page and images copyright 2007 Bryan Smith. All rights reserved.)