Mab is correct. A ram pump wastes a lot of water and runs slow.
That water is not wasted (even though it exits by what's called a "waste gate"). Releasing it at a lower level is what's providing the power to lift the payload water.
A Rife Ram Pump is made with cast iron. They are rated at 7 times the elevation per foot of head. The modern version of PVC pipe Ram pump will never reach that comparison, simply because the PVC will expand from the pulses of air that forces the water uphill.
Really? I was under the impression that a ram pump could lift water essentially arbitrarily high, at progressively lower flow. That a ram pump of a given size might be rated for a given flow at a height at a given multipler of its input head, but that if you were willing to accept half that output flow you could get twice the lift with the same input flow. And you can keep this up until the pressure is so high that the check valve, waste gate valve, or material fail, the parameters make the oscillation stop (though you can adjust them and get it back), or parasitic losses like leakage or mechanical imperfections prevent further pressure rise.
If you map water flow to current and pressure to voltage, a ram pump is an EXACT analogy of a boost switching voltage converter:
- The ram pipe is the input inductor and the momentum of the water in it is the inductance.
- The waste gate is the switch transistor.
- The hydraulic forces on it from water pressure and flow (including the inverted reflection of the shock of its closing from the discontinuity at the far end of the ram pipe), its mass, and its weight or spring are the driving oscillator.
- The check valve is the output diode.
- The pressure dome is the output capacitance.
- (If it doesn't have an air bladder, the snifter hole provides replacement for air lost into solution, to avoid its "breakdown" and maintain its design "capacitance", in a way that an electronic capacitor does not need.)
- The output flow is the output current, at a pressure that is the output voltage.
Run a switching voltage booster at a given duty cycle with no feedback, and as you reduce the output current the voltage will rise until it's high enough to stop, during the switch-off time, the current that build up in the coil during the switch-on time. Same thing happens with flow and pressure in a ram.
When that waste gate closes the water in the pipe is flowing, with a mass and speed comparable to a small vehicle. The only thing that can stop it is the pressure on the output side of the check valve, and (like an oncoming train) some water is going to flow through the valve until the pressure slows it to a stop (or the valve opens and you do another cycle).
That momentum, times the liquid's velocity, is ENERGY, and it's going somewhere. There's nothing for it to do but pump water against pressure. Higher pressure, less water, but the product remains the same - and it's the same (less losses from non-ideal components) as the product of the pressure across and delta flow through the ram pipe on the other half of the cycle.
Now I haven't actually MADE one of these puppies. So can you tell me if/where I'm wrong? Or can somebody with experience tell us of whether they were able to get output head of substantially more than seven times the input head of a ram, or failed while trying?