bypass

[thirteen]

I know there is cost in everything but I have read in this section of alot of people haveing hammering of the water in there pipes sometimes bursting a jiont or section of pipe. I am going to put my system in next year and am planning on putting in a bypass so when I am working on my gen. or just servicing the power unit it will still flow. I should be able to slow down the flow or bypass everything. It will cost me another valve and some jionts. Would a preasure release valve near the end of the pipe help or would the reaction time be to late to stop hammering in the pipes. I'll have 750 ft of 4 in. pipe  buried fron 2 ft to 8 ft but only 34 ft of head. It will be used only 8 months per year for there is not enough water during the late summer.  

[wpowokal]

You will only get water hammer when sudden changes are made to flow, in the case you describe two possibilities arise.

I would place a shut off valve just upstreem (in the pipe) of the turbine for maintaining your unit, and a smaller air purge valve upstream of that. When closing this do so slowly and no water hammer will occure.

When first filling the line do so with the turbine end valve closed and air purge open then slowly allow the water to enter, how you achieve this is up to you, it could be as simple a a piece of board across the entrance such that only a small opening is made.

allan down under

[zeusmorg]

 Some people put a valve on the upper end of the penstock to shut the flow off for servicing. This will allow you to shut the system down without fear of the hydraulic pressure becoming too great for your pipes.  

[chainsaw]

I don't think you will have any trouble with water hammer if you close the valve slowly. You might consider a pressure gauge up stream from shut off so you can monitor the pressure as you shut down. The gauge will be invaluable to monitor your static, dynamic pressures and also to detect air in your system.

[fungus]

The key is just to turn it off slowly, you'll still get some small pressure surges but it'll be fine ..

Here's a video I took when I was in CAT in wales with a group early in the summer, if you look carefully at the pressure gauge at the end you can see it pulsing ..

[fungus]

D'oh .. forgot to post the link

http://video.google.com/videoplay?docid=3517305932752466411&hl=en