Venturi water pump

thingiverse

Pumps water or slurries using garden hose pressure. The critical parameters for pumping efficiency and hose/pipe connections are parametrisable. Single piece, no moving parts. https://www.youtube.com/watch?v=QxKf6R1Fu88 I designed this thing because I unexpectedly needed to empty a pool filter. The filter is basically a large sphere filled with sand and water and a small hole on top. A normal pump would get killed by the sand and emptying it by hand is no fun. Instructions The default design fits into a 10x10x10cm print envelope. Print as is, no support material needed. Almost solid infill and many shells and solid layers to make it as waterproof as possible. It will work with a small amount of leakage though. ABS is the recommended material, because then the whole thing can be painted with ABS+Acetone paste for better waterproofing. The default settings are to match a standard 40mm PVC pressure pipe, which, for some reason, has an inner diameter of 43mm. It requires a 1 inch thread garden hose adapter, commonly found with spray nozzles. See pictures. The dimensions in the diagram above correspond to some of the parameters in the OpenScad file. These are the critical parameters for pump efficiency. Theory of operation The nozzle turns the garden hose pressure into high speed flow. The high speed water flow after the nozzle generates a vacuum which sucks in liquid. The nozzle offset from the throat should be selected to ensure that the flow diverges to throat diameter just inside the throat. Inside the throat, the liquid mixes with the high speed water and is accelerated by it. The longer the throat is, the better the impulse transfer, but a long throat also increases friction losses. The mixed flow expands after the throat. This slows the flow, but increases pressure. The ratio of throat area to pipe area is the factor that determines outlet pressure. By changing this ratio it is possible to select between high flow / low pressure or low flow / high pressure. Warning: The combination of high pressure and printed plastic can be more interesting than expected. To avoid injury, please always submerge pump before turning on the garden hose.