Author Topic: ram pump and pelton wheel  (Read 8001 times)

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beau

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ram pump and pelton wheel
« on: August 10, 2016, 11:02:43 PM »
I have a site that has a low head(1.5meters) good flow etc but floods.
I have been considering a 100mm ram pump coupled to a pelton wheel for 24volt dc
any comments.
beau (Australia)

keithturtle

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Re: ram pump and pelton wheel
« Reply #1 on: August 11, 2016, 12:53:30 AM »
That low of head will not produce pressure for a pelton wheel.  If you have enough flow you could turn a poncelet undershot wheel https://en.wikipedia.org/wiki/Poncelet_wheel

Even a reaction turbine requires several meters of head to work

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Harold in CR

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Re: ram pump and pelton wheel
« Reply #2 on: August 20, 2016, 01:34:04 PM »

 One of my many projects I have going, involves using 2 motorcycle wheels that have PVC pipe halves bolted all the way around, like paddle wheels, and they will power an antique piston water pump. Both wheels will turn a single shaft that will be chain or cog belt drive to the piston shallow well pump.

 From experience, i KNOW a 1/4-1/3 HP electric motor will pump water over 120' elevation which I will use to help keep my reservoir pond have enough water for sporatic 250W generation, depending on the rains for 9 month rainy season in my area.

 The wheels and pump will be mounted on 2 pontoons from an old gold suction dredge, and tied off to trees, so water rise from heavy rains will still allow the wheels to turn while not washing the whole device downstream.

 If this system interests you, I can post a few photos of the wheels and the pump in a disassembled stage, for references for you.

 My steady supply of 20-40 gal/minute won't generate electricity, but 24 hours of pumping water 120' uphill will have some effect on how much I can drain down 170' to my generator turbine for a 24V semi off grid system, as I continue to add more generation. Lack of a metal lathe has been my holdup, but, I have a lathe almost built, so, hopefully I can make serious progress now.

 Damn electric just went off again while typing this reply.  >:(  Keep us posted and good luck.

DenverDave

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Re: ram pump and pelton wheel
« Reply #3 on: August 10, 2018, 08:12:00 PM »
I'm certainly not an expert, but it seems to me that either the ram pump or the water wheel (Pelton or other), are two approaches to use the power of water to pump water and would not likely be used at the same time for the same application.  I'm not sure what the trade-offs are or when you would use one or the other.

That said, I'm amazed at how little is being done or at least talked about to use water to pump water.

Adriaan Kragten

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Re: ram pump and pelton wheel
« Reply #4 on: August 12, 2018, 04:18:28 AM »
I assume that your main goal is to pump water. The advantage of generating electricity and using the electric energy to drive the motor of an electric pump is that the electric energy can also be used for other goals than pumping. In my report KD 598 (see my website: www.kdwindturbines.nl) I describe a small floating water turbine which can be placed in a river. The same idea can also be used if only a small head is available.

Assume that parallel to the main river you make a channel under an angle of 30° or larger with the horizon. At the top of this channel you have the PM-generator above the water level with the generator shaft also positioned under the same angle. At the bottom of the channel you have the turbine rotor. In stead of an open channel it might also be possible to use a big tube. The advantage of this option above a floating water turbine is that you will get much higher water speeds and that therefore you can generate a lot of power even for a small rotor diameter. But certainly you will need a much bigger generator than as used in KD 598. It might be possible to use a 34-pole generator as described in KD 560 or a 46-pole generator as described in KD 624 and connect this generator directly to the asynchronous motor of a centrifugal pump.
« Last Edit: August 12, 2018, 07:25:56 AM by Adriaan Kragten »

DenverDave

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Re: ram pump and pelton wheel
« Reply #5 on: August 12, 2018, 07:09:12 PM »
I was going to ask the trade-offs between ram pumps and Pelton wheels, but now I'm wondering if anyone has a Pelton wheel that pumps a smaller amount of water to a higher location or if they are just used for generating electricity?

mab

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Re: ram pump and pelton wheel
« Reply #6 on: August 13, 2018, 06:46:05 AM »
Peltons are normally selected for high head low volume hydro - so by definition you wouldn't use one to pump a small amount of water to a height as you already have water where you want it.

Unless they're an over-unity nut who thinks they can use a pelton to drive a pump to drive a pelton...

Harold in CR

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Re: ram pump and pelton wheel
« Reply #7 on: August 13, 2018, 10:47:34 AM »
Mab is correct. A ram pump wastes a lot of water and runs slow. 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.

 Centrifugal pumps are high RPM and will need a much higher maintenance schedule due to very fine sand particles scouring the internal parts. A piston pump doesn't care about the fine sand.

 Many years ago, there were "Mud Hog" brand trash pumps. These were a diaphragm pump with a 2 cycle gasoline engine, and they ran with a Grunt sound as the diaphragm was oscillated as it shoved the water, mud, sand,and small rocks from construction sites. They pumped volumes of water but I have no idea what elevations could be achieved. 

This is why I chose the old piston pumps. Water can be pumped a long ways and to higher locations with the gearing and positive displacement pumps. We had 1 piston pump pushing water for 2 households, but, both houses used conservative amounts of water.

 A multiple of pumps would also allow for down time maintenance while other (s) would be in operation.

 You may be well aware of what needs to be done. I just get carried away with ideas from 65+ years ago. Yeah, I'm that old. 75 in Nov.

keithturtle

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Re: ram pump and pelton wheel
« Reply #8 on: August 13, 2018, 11:55:49 PM »

 I just get carried away with ideas from 65+ years ago. Yeah, I'm that old. 75 in Nov.

With age comes wisdom, usually.  Thanks for sharing

Turtle
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Adriaan Kragten

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Re: ram pump and pelton wheel
« Reply #9 on: August 20, 2018, 03:37:17 AM »
The disadvantage of using a single acting piston pump driven by a crank mechanism is that you get a very fluctuating flow and torque. In my report KD 544 I have described a double piston pump for which the pistons are driven by a cam with such a shape that the upwards speed of a piston is constant for half the time. This results in a constant flow and a constant torque.

Ungrounded Lightning Rod

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Re: ram pump and pelton wheel
« Reply #10 on: August 23, 2018, 12:29:22 AM »
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.

Quote
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?
« Last Edit: August 23, 2018, 12:44:18 AM by Ungrounded Lightning Rod »

Simen

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Re: ram pump and pelton wheel
« Reply #11 on: August 23, 2018, 01:17:45 AM »
Quote
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.

Seen as energy, this is true, but it is 'wasted' in the way that you don't get to pump all the water you collect. :)

I've made a small ram pump out of 1" brass fittings, but i've only tested it at a small test site where i managed a fall of 1.2 meters over 7 meters length, and the maximum pressure i managed there, was 1.5 bar (21 psi) (12x the fall).
This was with a stiff 1" pvc-hose as a supply pipe, and it was clear in the way that the hose jerked with each pulse, power was lost...

I'm guessing that the '7 times elevation' for the Rife Pumps, are just a maximum for those pumps while they still deliver within specs. ;)
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Ungrounded Lightning Rod

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Re: ram pump and pelton wheel
« Reply #12 on: August 23, 2018, 09:30:01 PM »
Quote
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.

Seen as energy, this is true, but it is 'wasted' in the way that you don't get to pump all the water you collect. :)

You gotta get the energy from SOMEWHERE. :)

Ram pumps get it from the "waste" water.  If you have a little stream and need to harvest more than a small fraction of it, that's a situation where external power sources are needed.  Get your energy somewhere else and you get to keep that water a ram pump drains of energy and discards.

Quote
I've made a small ram pump out of 1" brass fittings, but i've only tested it at a small test site where i managed a fall of 1.2 meters over 7 meters length, and the maximum pressure i managed there, was 1.5 bar (21 psi) (12x the fall).

12x > 7x Q.E.D.  :)

Quote
This was with a stiff 1" pvc-hose as a supply pipe, and it was clear in the way that the hose jerked with each pulse, power was lost...

There's supposed to be pressure variation up the ram pipe.  Shutting the waste gate sends a back pressure pulse up the pipe, and when it hits the opening the flow keeps going, and the discontinuity sends an inverted low-pressure pulse back DOWN the pipe toward the valves.  The low pressure pulse's arrival helps pull the waste gate back open and keep the oscillation going in a snappy fashion.

Even without that, the flow in the ram pipe ramps up while the waste gate is open, down while it's closed.  If you ran a hose straight to the valve assembly, all that flow variation will result in a side-force variation on every curve of the hose.  Lots of wiggling.

If you want to eliminate that (and are really far from the source, where a hose is a good idea), try installing a couple stiff pipes, bigger than the hose and several feet long, for the last few feet to the valves.  One pipe from the valves, for several feet, then a sudden transition to a larger one, with a bend into a standpipe rising about twice the height of the incoming water and with the length from the joint to the if-it-weren't-oscillating water level in the standpipe about twice the length of the last stage pipe to the valves.  Then most of your oscillation flow will occur in these pipes and not bother your feed hose.

I'd feed it with a right-angle fitting into a pressure node, so all that back-and-forth energy stays in the ram pipes and the flow and pressure in the supply line is about constant. That should occur about midway along the double-length pipe's path from the size-change joint to the average standpipe water level.

But this might be serious overdesign.  And I'm not sure it would do the right thing.  :(

Quote
I'm guessing that the '7 times elevation' for the Rife Pumps, are just a maximum for those pumps while they still deliver within specs. ;)

That was my impression as well.
« Last Edit: August 24, 2018, 12:03:15 AM by Ungrounded Lightning Rod »

Harold in CR

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Re: ram pump and pelton wheel
« Reply #13 on: August 25, 2018, 01:13:41 PM »
Quote
That was my impression as well.
Yes, this is real time observations.

  My Dad used to collect old Ram pumps, Hit & Miss and throttle and governor engines, which is what Steve is using with his steam experiments. We dug them out of the ground more than 3 feet below surface. I have no comments or arguments with the complete write up from ULR. It's entirely possible that springs and such were weaker than when new, valves might have had small leakage, etc. We didn't rebuild them, just cleaned them up to working condition and sell them.

 I might have an old photo of a guy that used to make models and would have an action display using a small pool of water and showing the normal discharges, at one of the old Steam and Gas engine shows on the East Coast of the USA.

Harold in CR

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Re: ram pump and pelton wheel
« Reply #14 on: September 10, 2018, 08:35:39 PM »
 Now, here is mostly what is involved with making a PVC Ram correctly, and an actual "Rife Ram" of modern vintage. We dealt with the old round air chamber cast iron Ram Pumps which were also made by the Goulds Pump Co . The video maker is " Engineer 775", maybe a real engineer ?? Anyway, he has a 4 part series and shows in great detail the formulas involved and the pumps in use.

https://www.youtube.com/watch?v=4y_WWxWdn5A

 Hopefully this will clear up some confusion in this thread.
« Last Edit: September 14, 2018, 05:28:31 PM by JW »