A pre-requisite to making the pump will be 2 homemade check valves. You can learn how to make these cheap PVC check valves here!
Step 1: Watch the Video!
Step 2: What You'll Need
I thought it might be good to build a simple pump, mainly for learning purposes, and I wanted to do it with low cost materials.
I've wanted to build a PVC water pump for awhile, but the check valves were around $10.00 each. That seemed a little steep for a PVC build, so I made my own, which you can see in a different project.
I was inspired on the pump piston and chamber by a picture I saw on a google image search by someone who used the 1-1/4" and 1" sizes of tubes, and he mentioned he cut the grooves for the O-rings on a table saw. That was a new idea to me and gave me the inspiration to put this together.
The materials I used are outlined in detail in the picture.
Step 3: Making the Piston
There is just a little gap, but we actually need this to be air-tight to make a proper piston.
The best way that I know of to make an air-tight seal, is by using some rubber O-rings.
To cut grooves for the rings, I used a table saw, and adjusted the blade by holding the pipe flat on the table top, and lowering the blade until I could see that it would only cut about halfway through the plastic. The goal is to make a nice groove for the O-ring, but not to compromise the structural integrity of the PVC pipe too much.
I cut 2 grooves for redundancy. One at 1", and another at 2" marks.
I used some wooden braces to keep the pipe steady, and made the cuts by using one hand to hold the pipe on the blade, and the other hand to rotate the pipe slowly. Of course safety and caution are top priorities when working around power tools and open cutting blades.
The O-rings fit perfectly into place.
This end of the pipe also needs to be capped off to seal it air tight.
You can't really tell in the picture, but I've glued on an end plug that is solid. In the diagram I said it was a 1" plug, but in reality it was a 3/4" plug that I sanded down to fit inside the end of this 1" pipe.
Now this end of the tube is completely sealed.
Step 4: Finishing the Piston and Chamber
I got a 1-1/4" slip cap and used a 1-3/8" forstner bit to drill a hole in the center.
An O-ring was added into the inside of the cap around the hole, and put to the side for a minute.
To insert the piston, the O-rings need some lubrication, or the friction on the inside walls of the pipe will damage them. I used Vaseline, but some people have suggested Vaseline will eat the O-rings over time, and that some type of silicon grease would be better.
To the bottom of the 1-1/4" pipe I cemented on the coupling, 3/4" reducer bushing, short riser, and threaded Tee.
With the 2 O-rings lubricated, the piston should push air-tight into the larger pipe.
The modified slip cap can be cemented on top now, and when the piston is bottomed out, there should just be a couple of inches of pipe poking out the top.
Step 5: Painting and Cementing
The handle is made from 2 pieces of 4-1/2" x 1" PVC pipe cut from the scraps off of the piston.
Everything is cemented together as shown in the picture, and when the handle is complete, it cements onto those couple of inches of piston pipe sticking out of the hydraulic piston chamber.
This completes the piston, and adding 2 check valves to the threaded Tee at the bottom will complete the pump!
Note: Make sure your check valves are pointing the right way :)
Step 6: Testing the Pump
Using additional PVC pipe and fittings opens up many different options. The imagination is the limitation.
You could try making this into a pump to move water vertically, or leverage it with your feet for more of a bilge pump type approach.
This pump seemed to move just over 2 cups of water per cycle.
With the vertical pump approach, I could pump around 3 gallons per minute.
With the horizontal approach, I could move over 5 gallons per minute because I could put my weight into it and move it faster.
Step 7: Additional Features
The pump has an intake side, and an outflow side. If you hook up to the intake, you create a vacuum.
I blew up a balloon and attached it to the intake side, and on every stroke it got smaller and smaller until it was actually sucked inside the tube.
I tried blocking the valves from both directions, and when I pulled back on the piston I was met with a strong vacuum in the chamber, which pulled the piston back inside with considerable force when I let go.
Because the piston isn't physically attached to anything, the handle can rotate a full 360 degrees.
If you need to clean the piston, or add some more lubrication, you can pull the whole handle out like an oversized plunger. It goes back in the same way it came out.
I'm planning to use this piston design in future projects that require pneumatic and hydraulic pistons.
In my testing, the valves work great with air and water. I didn't have any gauges to test the strength of the vacuum so can't say how strong the vacuum would be, but it certainly does create one.
Step 8: Final Thoughts
If you haven't seen the video yet, you can still see it below.
If you liked this project, perhaps you'll like some of my others.
Check them out at www.thekingofrandom.com