Wirtz Spiral Pump
Or, a quick lesson in trial and error!
I go on a river trip with family every June, and this time I wanted to make a river powered water pump. I chose the Wirtz Spiral Pump design because it only had one moving part, and seemed mostly doable with just what I had in the garden and garage.
Similar to a coil pump, a Wirtz Spiral Pump is a spiral of tubing that generates a head as the pump is turned in the correct direction. When powered from the flow of a river, it is an amazingly simple device for pumping water.
Before beginning, I used the model developed by Peter Tailor to make sure I would achieve a head of at least 3 meters. This was a bit more than the height from the river to where we make camp.
I began by heating an ABS drainage pipe, forming a bell on the end to act as a collector, then attaching it to a garden hose with a makeshift rotary joint made from a PVC pipe repair assembly. I tied this bundle to a wood cross to run it manually and check the head was what I wanted. It pumped up above 3 meters, so I started the spoke assembly. This project is almost exclusively from material found in dumpsters.
My initial plan was to mount the rotary joint in an ABS pipe and use some 3/4" PVC pipe as the spokes, but after running it for several minutes, I quickly determined the assembly wasn't going to be stiff enough.
In an effort to create a stiffer wheel, I ripped a few boards from an oak pallet to about 5 mm and used steam to bend them into a circle.
After fitting these together and wrapping the hose into the center, I decided I needed a bigger wheel for the amount of hose I had, and realized I could get an old tire from the tire shop down the road. Figuring it was worth it to see how the hose fit, I went and got one.
It was the perfect size, so I drilled holes so it wouldn't collect water, attached paddles (ABS pipe cut in half), and used paracord as the spokes.
Here I sliced some HDPE sheet to use as bearing blocks for the ABS axle, and used a pipe clamp to hold HDPE stops to keep the axle from moving axially out of the bearing blocks.
The biggest challenge of this project was coming up with a way to suspend the pump in the river while staying at the correct height as the level rises and falls. The difference over a 24 hour period was sometimes as much as the diameter of the wheel, so I needed to build a floating platform.
I first built a chassis with wood and aluminum reinforcements.
Finally, it needed some buoyancy, so I attached it to the top of two storage totes, and used corrugated PVC roofing to make them more hydrodynamic. The river flows very fast, and a flat front would quickly submerge the assembly.
In action!
2016