An earlier concept drawing of the pump impeller contained a higher number of fins.

For a project on my engineering course we were required to develop a water pump for use in a power drill driven irrigation system. I have put together some pictures from the deign and manufacture stages of making a prototype.

Centrifugal pumps use a spinning impeller to accelerate water outwards from a central point. They allow a high flow rate, but do not offer as high a pressure as some positive displacement pump designs. However, due to their simplicity and very their low number of moving parts we decided to develop this design for our pump.

The original concept had the shaft going the whole way through the pump, and the water coming into the pump through a slot in the front plate. However, the design was modified to have the shaft being held by a bearing in the back casing which means that the back casing will not have to be sealed to prevent water leakage making it more efficient and easier to manufacture. The shaft will be supported at the front of the casing by a hole in the front plate. The new design also has a series of holes around the input of the shaft instead of one slot, and then the entire pump submerged. This will mean that less time and accuracy will be needed on priming and sealing, so again making the manufacturing of the pump simpler.

Ease of manufacture was an important factor to consider in our design, although a greater number of vanes provides a higher pump efficiency we have chosen to have only four; allowing for a more simple assembly and manufacturing stage.

We just have a few small modifications to make before we can test it out for the first time, hopefully in the next week. In total the pump construction time was around 6 hours, from raw materials to final assembled pump.