Using Pipe as a Weir
Using Pipe as a Weir
(OP)
How do you calculate the head over a pipe when used as a weir, and at what point does it not fucntion as a weir.
Thanks.
Thanks.
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RE: Using Pipe as a Weir
The head at the inlet of the pipe would just be equal to the height of the liquid level in the vessel. The head at the outlet would be zero, unless the pipe would be liquid full all the time, but then you'd be in danger of creating a siphon and emptying your vessel. The pipe would have to go up to an overflow pot or something.
OR...
Are you talking about a riser inside a vessel that comes up inside to a certain height?
The head on that one would be zero.
RE: Using Pipe as a Weir
If the tank was being filled at 100 gpm and was going past the height of the overflow pipe, what would the head over that pipe be?
I was just emailed some handy graphs on circular weir flow from 1964 by F. Caplan. Wish I knew how to post them.
RE: Using Pipe as a Weir
Look at this FAQ: FAQ238-1161: This how to post pictures in your post.
There's advice in a thread by BigInch somewhere, but this works
Patricia Lougheed
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RE: Using Pipe as a Weir
For a nozzle in the side of the tank the best reference is P.D. Hills which was published in Chemical Engineering, Sept 5, 1983, pgs 111-114.
If you are looking at a circular weir formed by the open top of a vertical pipe then an easy-to-find reference is Perry's Chem Eng Handbook. The reference I have here is to the 4th Ed pg 18-9, but I am sure the newer editions will have it too. The Hills article gives some guidelines on when the head over this type of weir is sufficient to flood it and stop it working as a weir.
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