Syphoning Down a Lake
Syphoning Down a Lake
(OP)
As part of our process I will have to reduce the level in a small lake that forms on top of our waste rock containment by about 1 meter. The average inflow is 900 US GPM and the water will only have to be piped a short distance overt he final spill way. How would I get the flow started? I assume I will have to run the discharge to a lower elevastion than the suction, just enough to cover the head loss in the pipe?





RE: Syphoning Down a Lake
Can you dig a channel? That would be better or you could put in a permanent drain pipe. You could alos pump it out. Flow in a siphon is usually fairly slow, in the order of 2-5 gpm, depending on the installation. The larger ID of the pipe and the greater the difference in elevation the larger the flow.
Regards
Dave
RE: Syphoning Down a Lake
Definitely sounds like a job too big for rubber hose and mouth suction. Still, the principles would be the same. Discharge lower than outlet, get air out of the pipe.
Perhaps a pipe over the spillway, with a small booster pump to fill the pipe, and vents to eliminate air in the pipe. Once air is out of the pipe, flow should go naturally (you could leave the pump on, if desired).
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RE: Syphoning Down a Lake
The max "hump" that you can siphon over might be worth checking as well - you don't want to vaporize the water.
RE: Syphoning Down a Lake
If a hose is too large in diameter for the length, or flow is too slow, the hose won't run "full", and air can go back up the hose and release the vacuum. If this happens, you can submerge the outlet end of the hose in some small container that is filled with water.
The maximum height you can siphon over is determined by the lowest pressure you can get in the water without boiling it. For 70 degrees F (arbitrary number), this 0.37 PSI, and you should be able to siphon up to 33' or so, maximum. Somewhat less if you're at higher elevations.
This all assumes the hose is good for full vacuum (as opposed to a fire hose, which collapses flat without pressure in it).
RE: Syphoning Down a Lake
RE: Syphoning Down a Lake
RE: Syphoning Down a Lake
Your idea is interesting. But will the siphoning really start as soon as the water lever reaches the hump? What happens to the air that has entered the pipe? Have you tried this or is this just your theory?
RE: Syphoning Down a Lake
One quibble with an earlier post - the requirement isn't "discharge lower than inlet" - it's "discharge lower than surface of the reservoir"
A.
RE: Syphoning Down a Lake
So, what you're saying is maybe it's okay for the inlet to be above the surface of the reservoir? If you can accomplish that, then you are truly an amazing engineer.
RE: Syphoning Down a Lake
RE: Syphoning Down a Lake
For people who didn't visit other forum, it was suggested by a member to put valves at both ends and a vent valve(also a provision for priming) at the highest point of the pipeline.
Regards,
RE: Syphoning Down a Lake
RE: Syphoning Down a Lake
pump bhp = (GPM x Ft wg. pump head)/(3960 x .65)
The above formula assumes 65% pump efficiency.
You would be in the 10 hp range. You should pump & get the job over with as quick as possible since time cost money!