For some reason the photos are upside down here, but rightside up on my computer. Hmmm.
I needed a hand-powered water pump for a kid's toy, but the hardware store version cost $30 and was the wrong size. This one costs around $10, depending on what scrap supplies you have lying around.
The basic problem is to make two "check valves" as cheaply as possible. These are 1-way valves, in this case operated by superballs I liberated from the kids' toy basket.
Here's your parts list, most bought from Home Depot. Total cost: $10.47.
- 1 1/4" x 1/2" PVC bushing, screw type on 1/2" end (2)
- 1 1/4" PVC Tee (1)
- 1 1/4" x 1" PVC bushing, pressure fit both ends (1)
- 1 1/4" x 1/2" PVC bushing SPGXS (1)
- 1/2" x 3/4" PVC male adapter SXMPT (1)
- 1 1/4" PVC elbow (1)
- 1 1/4" x 2' PVC pipe
- superballs, small enough to fit inside 1 1/4" PVC pipe with some room to play (2)
- dowel rod or square wood rod to serve as plunger, as large as possible to fit easily inside 1 1/4" PVC pipe
- rubber or rubberized foam source to seal plunger. I cut up an old foam floor mat. An old sandal would work, too.
- screws to hold superballs and plunger seal in place (3)
- Optional: PVC primer and cement, depending on how permanent you want your pump to be
Step 1: Layout of Parts
Step 2: Secure Balls in Place
1/2-way through the T and the elbow worked well for me.
Step 3: Assembly
After each step, use a rubber mallet to tap pieces into tight fit.
If you plan to cement it together, I recommend dry fitting first, about 1/2-way inserting each part to test you have it all right.
Look to notes in the photo mouse-overs for details on how each piece fits.
Step 4: Making the Plunger
Screw it to the end of your dowel.
Trim it stepwise until it fits snug, so no water can escape around the plunger but so it's still easy to slide. A disk or drum sander will make this trimming easy, if you have one.
You may wish to drive a screw into the side of your plunger dowel rod to limit how deeply it can pass into the plunger pipe.
And you're done!
This gives you a general purpose pump, that can be adapted with screw-in fittings for any other pipe or hose you wish to attach. Though I started this for a children's toy, it's actually quite robust, and with the rubber balls as valves, should last for years. The plunger is the most fail-prone part I bet, but also the easiest to replace/repair.
I see no reason this could not be scaled up to whatever volume of pump you want, by extending the length of the plunge pipe or using different diameter PVC pipes with larger balls.
Step 5: Fully Assembled
This is just a photo of how I put it to use, in a toy pump for my kids. It easily squirts water 20'.