A spiral tube water wheel is a method of pumping water by using an undershot water wheel which has a scoop connected to a spiral tube. As the wheel turns the scoop will alternatively introduce either water or air into the spiral tube. The pressure generated from the column of water introduced by the scoop is added to the pressure from previous scoops and so as the wheel turns it will increase the water pressure with every turn of the spiral. These wheels have only one moving part and have been known to pump water with no maintenance for several years.
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Examples
Several Spiral tube waterwheel pumps were built in Zimbabwe-Rhodesia in 1979. These ranged from one meter to four meters in diameter. See details written by Peter Morgan in the aquamor.info website (www.aquamor.info) A good example of a spiral tube water wheel can be found on the Rock Farm Estate in Belize, where, for several years, 25 gallons of water a minute are pumped from Roaring Creek by a wheel.
Tubing Coil Layout and Hydrostatic Head
Each coil of the tube helps increase the available head pressure, effectively increasing how high the water can be pumped. Successive coils are wound such that their outer diameter is slightly less than the inner diameter of the previous coil as the tubing spirals in. The diameter of the coil is much larger than the diameter of the tube, so the diameter of each additional coil decreases only a small amount. Due to the alternating water and air that is taken into the tubing the pressure of the previous coil gets added to the pressure in each coil. If the coils are about the diameter of the wheel the apparatus will pump water to a height of approximately the coil diameter multiplied by the number of coils. As an example 3 coils that average 4 meters in diameter could pump water up to about 12 meters above the water surface. At the outlet there will be alternating water then compressed air coming out of the water tubing.