What plastic pipe to use for a hydro power scheme

We are often asked to supply pipework for hydro power systems, especially micro units and have a lot of experience in advising the right solution for you. So here are our top tips:

1. The pressure rating of your pipe should increase the further down your line. At the start of your line, the pressure will be much lower than that at the end, so great savings can be made by installing a lower pressure rating of pipe at the start of your line, increasing the pressure rating as you go down the line. The lower the pressure rating, the the thinner the pipe wall and so the less plastic is used = cheaper pipe.

2. With the above in mind, survey the entire line so you can make an informed decision on when you need to change up pipe pressure. 10m elevation (in other words 10m down a hill) adds 1 bar of pressure.

3. Materials choice tends to come down to PVC or PE, with PE being the preferred, and usually, cheapest option. PVC is only usually chosen in very remote locations as it can be installed without specialist equipment / engineers, which can be very costly. As well as lower cost, PE pipe has the advantage of being more flexible and impact resistant. a PE pipe will happily flex and follow the landscape, whereas a PVC pipe is far more rigid and, in an undulating landscape, will need support.

4. Keep the friction loss of your pipe in mind. Small scale hydro schemes are littered with instances where someone has a nice head, but then puts in a pipe too small, which creates a lot of friction and reduces the pressure by the time it gets to the generator. Our free online PIPEFLOW CALCULATOR tool will help you work out the right size of pipe. Basically - go too small and you will lose efficiency, go too big and you will spend unessesarily on your pipe.

5. When you are installing valves, install full bore type valves like gate valves and ball valves. Butterfly valves will increase friction loss and reduce efficiency, even when they are fully open.

6. When installing bends, tees etc. try to make the flow pattern as smooth as possible. Use wide radius bends rather than sharp elbows and where possible, 45 degree tees rather than 90 degree ones.

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