type of pipe for penstock

[dscheckman]

Hello all, I'm working towards a small hydro installation and right now I'm obsessing on ways to save money on pipe for the penstock.[ 500ft.] There is 38ft of head and max. 150 gal per minute flow. [ a good bit less some times of the year] 4" pipe seems about right. I might use 5 or 6 if it came my way but it seems to be right on the margin and 4" is so much cheaper. It's a very narrow ravine, pretty hard to get to, I think plastic pipe is a must. All the work will be by hand, no possibility of getting equipment to the site. Will sdr 35 [ green] work or is schedule 40 a must? Is there any type of affordable flexible 4" pipe that can work? Not much salvage available in our rural area. Lowest cost that will work is important. Thanks for any help.

David Scheckman

Vermont

[wdyasq]

38' head is less than 20psi pressure - IIRC.  You codld plan around that and make sure it can drain incase it has to go through a freeze.

Ron

[Nando]

David:

38. feet = 11.8 meter head
    
150. GPM= 9.45 liter/sec
     
     

Expected power would be 11.8 * 9.45 * 9.81 = 1094 watts of power

For 500 feet = 153 meters of pipe with 12 meter head you may use a 4 inch Drain pipe without any problem, cheaper indeed !!.

4 inch is very good for your water volume and head, indeed, larger diameter may add a few % additional power due to less friction losses.

If you find 4 inch flexible pipe, let us know the source, Please

What is the distance from the Turbine to the load ?.

1 KW may give you around 600 watts at the load - my suggestion is to have AC instead of DC for the Capability of using the AC straight without conversion and of course you may have a battery bank for additional immediate available power.

Nando

[dscheckman]

Thanks for the responses, Does anyone know how much pressure sdr 35 green sewer pipe is rated for? I can't seem to find any , I think because it's normal use is un-pressurised. My guess is its way over the less than 20lbs psi I'll have, hopefully enough over for possible air hammers. Nando, Its about 500 ft. from the turbine to my house. My current plan is:

orange spoon turgo wheel[homemade with spoons from Joe H.]

Smart drive configured to 48volts dc

48 volt battery bank

grid interactive inverter so I can still use a little grid power [ which we have now ]when needed.

What do you think?

I'm also looking for suggestions/references for dam set ups. The site is quite narrow with a lot of sandy sediment moving through. I'm thinking something like a double dam. First dam to trap sediment, second to house the inlet. Any good designs out there for self-cleaning inlet boxes? Thanks again, David

[wdyasq]

David,

'Water-Hammer' occurs when water changes direction or stops. When the mass of water is required to stop or change direction the inertia of the water causes things to break.  In high-pressure high volume pipelines it can get interesting.  

I would suggest good blocking for hard turns and the power station itself.  In short, any there is an abrupt change.  Also, you should have a valve at the head and foot of the project. To fill, have both valves closed. Open the head valve slowly and let the pipe fill. Once you believe the pipe is full, leave the top valve open and fully open the lower valve to get all the air out.  You will want to open and close the valves slowly when doing so.  Especially at the final stop or start of flow. According to my calculations you will have approximately 11,000 pounds of water (500lf of 4" pipe).

Good luck,

Ron

 

[Nando]

Drain pipe has 40 PSI rating.

Can you calculate the RPM and the Diameter of the Turgo ?.

Joe can assist you there, well,

It may be necessary to have a special Turgo plate.

Since you are planning to use a Smart Drive and the distance is 500 Feet let me suggest NOT to modify the S&D windings and leave them as coming from the factory.

Use 3 transformers to bring the Voltage down to the necessary voltage ( 65 to 85 Volts) and use a MX60 to attain the maximum power available.

A bit more expensive but the power harvesting would be at its maximum.

To get the 1000 watts you will need to run the S&D at around 1100 RPM, so get a motor(1.0, 0.8 or 0.60 Size ) that gives the output voltage the transformers need.

This way the transmission loses would be at a minimum and a # 12 Size, 3 wire will do the job, wire that is a commodity throughout the world

Regards

Nando