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I have a micro hydro setup with about 400 meters of 2" white stripe irrigation pipe, putting out 8 amps @ 12v which is great at keeping the batteries topped up in times of cloud.
The problem is every time the creek rises the pipe either gets washed out or clogged with debris, these are the times i most need the electricity!(54ml of rain last night and its stopped again)
Any ideas? i think part of the problem is when the creek rises there is a lot of air bubbles in the water so the pipe gets an airlock possibly.. need some sort of DIY filter for the pipe end.
Hya happyantix
..
I have a 2"poly pipe as well that is mostly for gravity feed irrigation that I plan to also hook a water wheel too.
Over the last couple of years I have dealt with just your sort of dilema. I do have good quality take up screen at the inlet end that I have anchored with a star picket horazontally between 2 huge boulders in the middle of waterway. Attached to this is a short length of stainless steel cable. this sits in only a small pool in the middle of a turbulent creek. Air locks can become a problem but I have a purge line that after heavy rain I open up fully and any air,sand or derbris gets flushed out. Also the pipe is settled in amongst some rock and kept at least 6 inches below the surface..just upstream I manevoured a few rocks around to reduce the surface velocity thus reducing the bubbles getting down to the screen.
Now I know how hard it is to get 400 metres of gravity feed going again and for this I have a high pressure low volume 12 volt pump that I can run off a gen set or even a car battery. While this is refilling the poly pipe I head up and check the lines for air and either shake out or find the closest coupling and re purge from that point...just be sure that where the pipe leaves the creek needs to be temporar dropped to push out the air at the top end. after about 30 mins of priming generally there is enough (siphon" to get it running again.
Invest in a good quality screen for up the top as this will solve most of your problems as these can be fitted with the proper coupling directly to your polypipe and will hold via the steel cable and anchored star picket
Mud is just wet dust
VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539
Posted: 01:39am 25 Oct 2010
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Hi Happy
The filter I used with success was conical stainless steel, made from a sheet of heavy gauze they use for irrigation suction line for the pump, the holes where about 3mm. It was rolled into a cone about 12 inches in diameter with the large end welded to a plate. the outlet was at the bottom of the circle so it lets the air bubbles escape above the hole. The gauze came in 3 ft wide sheet by six foot long, so one sheet makes 3-4 filters.
The outlet was 6 inches round with a reducer about 12 inches away to the four inch pipe size, this was to reduce the water intake velocity to let any bubbles rise so not so much air was sucked into the pipe.
The cone was 3 ft long so it had a good surface area to let the water in without to much suction to attach debris to the outside, and the conical shape was better at self cleaning as there isn't any flat surface to attach leaves and junk, even so it needed cleaning off every week and after heavy flows.
On the point of the cone, the support rod from the back plate had a ring attached that was used as an anchor attachment.
This unit was used on a pelton wheel with 3 10mm jets with approx 30 meters fall over 1050 meters pip run.
There is no way to avoid air bubbles in the pool i have the pipe in currently, it is very small right under a waterfall, there is another pool i could use but the elevation is a meter or two lower, i'm not sure if that would affect the pressure much, but i could try it as it is a huge deep pool, if i could anchor it to the bottom (steel cable is a great idea, rope just stretches and breaks).
I will look into a filter, and get some photos as well to give you a better idea, thanks again for the help :)
Jacob
Barry T Coles Senior Member Joined: 30/07/2009 Location: AustraliaPosts: 109
Posted: 08:14am 25 Oct 2010
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Hi Happy
A couple of metre head loss wont make a great deal of difference to your pressure (about 14.5 PSI/metrehead)the difference will be in not having to reprime from air locks.
Cheers
BarryI need to learn from the mistakes of others.
I dont have the time to make them all myself.
I will give that a try, luckily the waterline runs alongside the hydro line, and runs into it with a valve, so i can prime it from the waterline if its stopped from airlocks.
I will post back with photos and some updates, i appreciate the assistance :)
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 10:16am 25 Oct 2010
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I remember seeing an interesting intake filter solution on 'the inventors' a while back.
It basically looked like 2 plough disks facing each other so they looked like a clam.
Water got in at the narrow slit (a few mm's) around the circumference and was drawn from the center of one disk. The other disk needs the center hole welded shut.
While I have not tried this idea it looks rather clever and promising, besides being easy to build. Just weld a few spacers to keep the disks the required distance apart.
No mesh to clog up either, the narrow slot limits what can enter and bigger debries just get washed away.
Klaus
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 02:00am 28 Oct 2010
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happyantix
Something else you might want to give some thought to is this:
As much trouble as it might be to get a concrete meter box up to the top of the hill, still, digging out a spot for it amongst the smaller rocks at the bottom of your pool and placing the box so it both holds down the screened end as well as acts as a covered housing, it might be enough to dissuade both debris as well as air from entering the pipe.
To make it more effective as well as just a bit lighter, you could drill several 1/2" holes in all 4 sides as well as the concrete lid to allow more water entry.
Cutting a concave notch in the bottom side would allow it to fit snugly over the pipe. I'd use some of the larger small rocks to "filter" water entering from under the box as well.
Just a thought.
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
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