Himani: The penstock should have a valve and at the same time a T with a piece of pipe above the intake level for cleaning purposes, there are many pipes that are clogged with algae and debris, specially if a good filter is not installed to the intake, also at the end of the pipe run another valve to close the system when in repairs or maintenance, in some cases a T has been installed with a valve for a secondary use of the pressured water.
The added cost of the upper arrangement is minimum compared the usefulness of the posterior use of it. Closing or opening either valve should be done slowly for at least 10 seconds for about every 20 meters of head and pipe run. Regards Nando ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, June 02, 2005 4:52 PM Subject: Re: [microhydro] Gates/Valves at top of penstock > Himani, > > It might be best to have two valves, one at the top of the penstock for > isolation and one at the bottom for the control that you mention. It is difficult > and extremely unwise to try and control from the valve at the top of the > penstock, like trying to push a string. The likely scenario would be to > partially drain the penstock and then open the valve at the top. When the water > columns collide you will develop a water hammer such as you have never seen and > don't want to see. If you don't have enough money for two valves go with a > single valve at the bottom of the penstock. S l o w l y is operating rule number > 1, avoid shutting the valve down too rapidly. Some of my big penstocks require > 1/2 hour to make a major rate change. Your small Hydro is a bit more > forgiving but the same physics apply. Good luck. > > Bob > > Robert K. Weir P.E. > Hydroscreen CO. > _www.hydroscreen.com_ (http://www.hydroscreen.com) > > > [Non-text portions of this message have been removed] > > > > > > > Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! > > NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. > > More information on micro hydropower at http://microhydropower.net > > To unsubscribe: send empty message to [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> In low income neighborhoods, 84% do not own computers. At Network for Good, help bridge the Digital Divide! http://us.click.yahoo.com/EA3HyD/3MnJAA/79vVAA/FGYolB/TM --------------------------------------------------------------------~-> Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/microhydro/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
