Hey all, I know several of you guys have made ram pumps before, so I thought I would see if I could get some input. I ordered parts to tie into my hydro penstock, which is usually shut down in the summer due to lack of water (I have not measured the flow yet, but it is quite a lot, just not enough to generate much power).
Here is the basic layout
I might have slightly more than 8 feet of head, should I use as much as possible, or will the pressure get too high if I overdo it? Also, since the penstock is closed for a long distance back up to the source, I am thinking I will need a standpipe to help the shock wave dissipate at the top of my 2" drive pipe?
I have started laying out my pump body, which is made of 1-1/2" iron pipe;
I made a custom T at the far left, onto which I will be affixing the waste valve. This is my thought for that (forgive the crude MS-Paint CAD drawing )
Basically there will be a restriction that the valve plate can shut against, and then in the upper section I will mount an inch of bushing to guide the shaft. How much clearance do you think I should leave around the edges of the plate? Should there be enough travel for the plate to drop all the way down into the perpendicular section? I will probably drill some holes so the water above the waste valve can drain out, but I have head some people say that water above the valve helps to make it self-priming by adding a little weight temporarily. I am thinking the shaft will be all-thread, so I can easily adjust the travel length and also add some weights to dial in the waste valve cycle.
I made my check valve out of 1/4 rubber sheet I had from another project.
The threaded end on the right of the pump body will go into a T, where I will connect the expansion tank, and a reduced down drive pipe. Inside the pressure vessel (old fire extinguisher) I put several sections of closed cell foam from some pipe insulation.
I will probably also include some robust mounting feet to bolt it down to a little concrete pad. Does anyone have any input before I start welding? I am hoping it will come together with a minimum of bought parts. I need to get going too, as summer has finally arrived, and it will be time to start irrigating soon!
After assembling everything, it dawned on me that the height of my T adds quite a bit of travel to the waste valve. I am not really sure how much water will flow until the flap drops down into the perpendicular pipe:
That means the flap needs to be raised like an inch and a half to get it to seal against the restriction.
I am not sure if that is too long of a stroke or not, or if I will be able to fine-tune the travel distance and weight to get a good frequency. I have heard people say anything from 60-150hz is what I am aiming for.
I guess now I need to get some pipe and actually test it out!
Sure enough, the first attempt was not a success. Here is the assembled pump:
I did get the penstock set up, and it seems to be working well. I decided to just add a valve to my 4" pipe and fill a tub at the top of the hill. I think I have almost 10 feet of head. When I open the valve at the top I get a torrent of water, which filled a 6 gallon bucket in about 6 seconds. I am not sure it could keep up that flow rate, but I will easily have 15 gpm, which is as much as I think my 1-1/2" pump will be able to use.
It was a nice sunny day, so I did spend some time just playing with it, and if I kept pushing the plunger down it would pump. I got it up to 21psi, and there was a tiny bit of water at the the outlet. There is just way too much travel, so the plunger goes to the top and just stays there. If I had several pounds of washers, it might have worked… I think I am going to take it back up to the shop, chop down the height, and switch it to a spring-loaded waste valve like the one above.
One thing to consider aside from excessive travel of the plunger: when the it goes to the top and stays there, it is (in part) being held there by pressure against it. In other words, the head pressure from water in the drive pipe doesn’t let the plunger drop.
Immediately after a power stroke, when the check valve closes, a water hammer pressure wave is reflected back up the drive pipe. When it dissipates, there is a moment of equal pressure on both sides of that waste valve plunger and it should fall at that time. If for some reason, that moment of equilibrium is too short, or the weights atop are too light (etc), the plunger won’t drop. However, you can cheat and give it a fighting chance by considering the use of a riser open to atmosphere in the drive pipe (a place for the pressure wave to go) and/or by increasing weight.
I think I made a few posts and pasted some links on this subject in kristjanL’s homestead thread.
Okay, I gave the waste valve another go. The Mexican design was super easy to make, and was really easy to adjust the tension to get it running on its own.
Here is my current setup.
The sandbags do a pretty lousy job of securing the pump, so it tries to jump around a bit with each stroke.
At the top of the hill I have a tub, and you can feel the pulses come flying up the pipe and dissipate.
Here is the outlet.
I am only pumping about a gallon every 3 minutes, so it should move about 480 gallons per day. I estimated that I was putting something like 6-10 gpm into my tub, so my efficiency is not good.
I added a rubber gasket to my waste valve after the first picture was taken, but it seems it was too small. The edges are not staying flat, so the seal it makes with each stroke is not very tight. Edit: Rewatching the video I can hear it hiss after each “clunk,” which is probably the sound of the water I should be pumping escaping out the gasket. I am hoping that between fixing that and casting a heavy base to bolt it to, I can squeeze a little more flow out of it. I took a short video of it running, I will post it in a few.
Got to love a simple machine doing real work. There is another variable, the pressure vessel, it would be interesting to see how that influences performance, I would think a larger vessel will slow down the stroke rate, but maybe increase the efficiency at low head?
There is also an issue of friction and water surface tension in that equation.
Amen Garry. I think you are right about the bladder tank.
Also, that manual you posted is excellent. I really like that series of pamphlets. I have used a couple of them. There is a whole series, I wish I could find a complete set.
I glued the rubber flap to the steel washer with superglue, and that seems to have done the trick. The valve still leaks a little, but it is much better. I took some measurements: I am putting 12gpm into my tub, and I am now getting 1.5gpm at my outlet! I will take another video tomorrow of the new setup.
I experienced some strange behavior when I failed to get the drive pipe fully purged of air, like super fast pulses, and what I think was cavitation at the top of my drive pipe. It stalled at some point during the day when the nut holding the valve worked itself off, so I am not sure yet on what to expect in terms of dependability. I am trying again with 2 nuts. I am hoping it will still be pumping tomorrow morning when I go down to take pictures.
The pressure tank seems to be providing enough buffering capacity, but the pressure climbs really fast with the new valve. I started it running with like 10PSI and my delivery valve shut, and it was up to 40PSI in a few seconds. I am a little curious how high it would go, but I dont know how much pressure closed cell foam can handle… 40PSI is getting pretty close to being able to pump to the highest ground on my property anyway.
Its what l use. Preety much indestructible and all you do is use one stock for the non return valve and flip the other around with the plunger spring inside removed. The geometry and weight of the flunger is somehow ideal.
One wery important thing people tend to forget is the hydraulic shock wawe not only creates a positive spike but allso a negative one! If the geometry and weight of the waste valve is right the negative shockwawe will open the valve and aid to reliability.
Well the pump did not run overnight, and had stalled with the valve open. I loosened up the spring a bit, and now it is cycling a bit faster, but still pumping the same quantity of water. I counted about 170 cycles per minute.
Fingers crossed that it keeps going this time. Have any of you others had problems with a pump stalling?
The changes to the spring tension seem to have done the trick. I am past 24hrs of run-time, and the pond level has come up about 3 inches. I know that there is a leak somewhere, but I guess I am going to find out if it can drain more than 1.5 gpm! Has anyone here had success sealing a leaking pond?
Are you thinking of bentonite? It is what they use in kitty litter, and is just a very absorbent clay. Disposable diapers use super absorbent polymers, i believe. Not sure what they make those polymers out of, but we decided to just stick with cloth diapers. We got a couple dozen free diapers, and it was amazing how much garbage they produced. But yeah, I have changed a lot of diapers. And done a lot of laundry.
That polimer is what l was talking about. My guess is the plan is for the grains to get in the cracks of a pond then swell and plugg them. I think that polymer can absorb up to 40 times its weight of water!
You are brave. We too tryed washable dipers. But gave up soon. It was a huge chore that we culd not cope with at the time. Specialy later with 2 diper fillers!
Luckly both are diper free now. What a releaf on time, money and dumpster space!
Bentonite clay is very sticky. Well drillers use it to seal sand collapses when drilling wells. Also a slurry is pumped around the outside of leaking basements sometimes. A thin slurry of it will do a lot of sealing. It can commonly be found at feed mills and farm coops. There it is used in small quantities as a binder when making different feeds.