# Water pump question



## Amber (Jul 29, 2011)

I'm wondering, has anybody tried using goodall valves for the one way valves on a manual water pump? I kind of doubt that I'll be able to find any small check valves in the local plumbing departments of the local stores. I might get lucky, but just in case I don't, I might make a pair of goodall valves for the water pump. I know that water can be pushed through a goodall valve, but can it be pulled through one? Possibly an interesting experiment.


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## Semper Vaporo (Jan 2, 2008)

I can't think of any reason why it would not work. Just need large enough cavities for the business end of each valve, so the hose material can expand a wee bit to let water flow. Might make for a kind of klunky looking pump housing, but the one-way valves do not have to be immediately adjacent to the pump itself. Large cavities for the valve might make for a lot of air to be expelled before water moves, but once primed it "should" work... I think!


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## Amber (Jul 29, 2011)

I suppose it wouldn't hurt to put in a primer plug so that you won't have much air to pump out before it starts pumping water.


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## Phippsburg Eric (Jan 10, 2008)

I think the priming might be the issue. if you have a larger volume in the section of pipe etc containing the pump plunger (between the valves), when air is in that volume you will not get as much vacuum to suck water in to start the pumping process. 

The pump works by varying the volume of water in a section. as the pressure decreases when the volume increases (the plunger is pulled) water is sucked in through the inlet check valve. as the volume decreases (plunger pushed in) the pressure rises and water is allowed to exit through the outlet check valve. Because water is not compressible, it doesnt matter how much extra volume there is between the check valves. 

but with air, you can see that if the volume is larger ( in proportion to the plunger), the motion of the plunger only changes the volume a smaller percentage, thus the pressure would change a smaller amount too. If you can force water in through the inlet check valve, to fill the pump cavity, you should be all set. 

The Goodall valve system will require more vacuum (difference in pressure) to get flow than the ball type check valve. if you are making the valves, you may be able to play with things to reduce this necessary pressure difference. If you have to buy the valves, you might as well buy a pump or at least proper ball check valves. 

For your test use a spray bottle as a pump and one Goodall valve on the boiler...that is certain to be the cheapest solution, you can top up the boiler with the same rig when operating it under steam too!


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## David Leech (Dec 9, 2008)

My bet is that it will NOT work. 
The equal suction on the silicon tubing will not be enough to open up the passage way. 
Pushing water through a Goodall valve probably just bulges the tube on one side only. 
But, someone should try it and prove me wrong, and let us know. 
Then even if it does, the volume of water passing through may not be equal to a regular ball check valve. 
All the best, 
David Leech, Delta, Canada


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## steamboatmodel (Jan 2, 2008)

I think you would be better using a sprayer bottle or dissect a water pistol. 
Regards, 
Gerald.


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## Semper Vaporo (Jan 2, 2008)

I agree, a spray bottle, or water pistol would be more expedient (just not as much fun as making one from scratch). It is surprising how much pressure one can get out of a simple spray bottle. Surprising how strong the plastic is under such pressure! Of course the water is not HOT, so the plastic does not thermally deform! 

Just don't use one that was designed to displense only hand-soap! I tried that once and the spring inside was not stainless steel and it very rapidly (less than a day!) rusted and the water came out brown with tiny flakes of the spring in it! Any general purpose spray bottle should not have that problem (nor one for dispensing thin liquid cleansers, as they are mostly water so the spring would rust if it were not something that won't).


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## Amber (Jul 29, 2011)

I'm working on both a spray bottle pump and a manual piston pump right now, The spray bottle is fairly easy to set up to pump the water, but I don't know what the boiler connection looks like. Is it just a snug fit between a hole in the end of the goodall valve fitting and the tip on the hose line from the squirt bottle, or is it more complicated than that? Another question, how tight should the silicone tubing be on the outlet tube of the goodall valve? On the parts that I'm working with right now, the silicone tubing slides on the copper tube relatively easily. I'm not sure how it stays on the tube, or how tight the silicone tube is supposed to be on the copper tube. 
Another question, do the manual water pumps have a piston ring? I'm planning on putting an O ring on the piston to get a good seal on the pump barrel, I can see how the water would just be squirting out around the piston otherwise.


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## Steve Shyvers (Jan 2, 2008)

Amber, 

An alternative to an o-ring on the pump piston is to use a gland seal (like a faucet stem packing) where the piston enters the cylinder. Maybe do both. Usually the small hand pumps used for model steam locos use a length of constant-diameter round material for a combined piston and piston rod, instead of having a separate piston attached to a smaller diameter piston rod. Easier to fabricate, robust against side forces from the pumping process, and therefore easier to keep in alignment in the cylinder. For valves you could try using automobile (or bicycle) tire valves. I believe that they use an uncommon thread size, but maybe you could use a complete valve stem as the housing for the valve, plus some thickwall rubber tubing and hose clamps to adapt the valve assembly to your pump setup. 

Steve


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## Amber (Jul 29, 2011)

The pictures of the small hand pumps that I looked at showed the piston coming out of the back of the pump cylinder and having a slot in it for the pump handle, as you said, so that's what I was planning on doing. It certainly looks easier to make using just 1 piece of rod for the piston and the push rod. Cutting the slot on the back end of the piston for the handle shouldn't be too hard. If the stainless rod won't cut very easily with a hack saw, it'll cut with a cutoff disk in the angle grinder.  
Making a gland seal at the back end of the pump cylinder might be a bit tricky, but it might be easier than cutting a slot in the piston for an O ring seal. Now that you've mentioned it, I think I may have a workable idea for a gland seal, depending on what I can find at the hardware store. 
I think a large goodall valve should work pretty well for the out valve for the pump, for the in valve, I'm not so sure. I'm going to try it just to see what happens, but I probably should look for a small check valve for 1/8th pipe thread, or 1/4 inch pipe thread. Either one would work.


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## Nutz-n-Bolts (Aug 12, 2010)

I have been doing a lot of thinking on building a water pump as well. Mine will be servo driven for my ruby. In my search for check valves I turned these up:

http://www.specialtymfg.com/check_valves_brass/212_check_valve/default.asp

Using them means I only need fabricate a manifold and piston for the pump. I haven't attempted to order any yet. So I'm not sure of price. 


I also found this one at grainger:

http://www.grainger.com/Grainger/CDI-CONTROL-DEVICES-Compact-Check-Valve-6D917?Pid=search

I'm curious to see what you guys think of their use in our application. 


Also for a typical "rod and gland" type pump discussed above what kinds of clearances are involved? What would the OD of the rod/shaft be and the ID of the bore?




PS: I just noticed the Grainger vales I listed are pneumatic their hydraulic ones don't seem to come that small.


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## Steve Shyvers (Jan 2, 2008)

Randy, 

In theory the gap between the cylinder wall and the cylindrical combined piston/shaft, which is often called a "ram", is not critical, because it is the volume displacement of the ram moving in and out of the cylinder that provides the pumping action, provided the gland seal remains tight. However the smaller the gap the easier it is for the gland seal to do its job, the less space there is to get an air bubble trapped in there (which will kill the pump's effectiveness), and the more support there will be for the ram. If you can achieve close to the clearance between two pieces of telescoping K&S brass tubing then you are doing well. 

For a hand pump a ram diameter of 5/16" or 3/8" should work. You don't want it too big if the check valves and piping won't allow a corresponding volume of water to pass through them. You don't want it so small either that you have to pump like mad to fill the boiler. 

Steve


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## Amber (Jul 29, 2011)

I got a bit more done on the water pump build tonight. I cut the stainless rod to length for the ram, and then cut the notch in the end of the ram for the handle. This stainless is easier to work with than I had expected, I was able to cut it with a hack saw, both for the length and the notch. I finished the notch with a small file. I still need to drill the hole for the handle pin. I still need to find the part that I need for the gland seal retainer, and the right size of O ring for the gland. I also have to make the handle and the mounting parts for it. I have 1 of the goodall valves for the pump half built, I just need to block the end of the tube and drill the outlet hole. 
I'm going to have to find out if I can run a tap into this stainless rod, I'm planning on using pieces of it for the pistons for my steam engine and I want to thread the piston rod into the piston.


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## Phippsburg Eric (Jan 10, 2008)

I think you will be able to make a very nice pump either way, the goodall valve system for a hand pump should work fine. I think it wouldnt work for a really small pump like an axle pump but a bigger hand pump should be fine. If you can get commercial valves they will work well too if you can plumb them in.


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## Amber (Jul 29, 2011)

I shouldn't have any problem plumbing in the commercial valves if I end up using them. I'm using 1/4 inch brass plumbing parts to build the hand pump. I'm using a tee for the end of the pump body and a short piece of 1/4 inch brass pipe for the pump cylinder. The valves will be connected to each end of the tee for the inlet and outlet. Interestingly enough,a 5/16ths diameter rod fits inside the 1/4 inch pipe pretty snugly. I think that the piece of pipe that I bought for the pump cylinder was slightly out of round, or perhaps slightly bent from being threaded, I had to run a drill bit through the pipe to straighten it out so the stainless rod would slide smoothly al the way through the pipe. It would get stuck on one end of the pipe. I also had to cut the end of the rod off, it was out of round from being cut at the factory. I still need to figure out how to attach the pivot for the handle. I think I'm going to have to silver solder something onto the tee fitting to attach the handle pivot bars to. With a commercially made pump, that attachment point is part of the casting at the other end of the pump from the handle. 
By the time I'm done with this, I probably will have enough money into the parts of the pump that I could have just bought one,but where's the fun in that?


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## Semper Vaporo (Jan 2, 2008)

I have made many items for the sheer joy and utter satisfaction of having done it myself







... then gone out and bought a commercial one so I can have something that works.


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## Amber (Jul 29, 2011)

Yes, that thought did occur to me...


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## iceclimber (Aug 8, 2010)

Posted By Amber on 14 Apr 2012 09:26 PM ...could have just bought one,but where's the fun in that?  


Much fun if you bought an Aster kit. Then while building you can learn a great deal of how things work and what you may or may not be able to fabricate differently.


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## Nutz-n-Bolts (Aug 12, 2010)

Posted By Semper Vaporo on 14 Apr 2012 09:55 PM 
I have made many items for the sheer joy and utter satisfaction of having done it myself







... then gone out and bought a commercial one so I can have something that works.










Doing something for you self is the best education you will ever receive. Buying one that work shows you smart enough to admit temporary defeat, because I'm sure you tried to build again!


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