Conical Weir
Conical Weir
(OP)
I'm working on the rehabilitation of an elevated storage tank. There is a 6-foot diameter conical overflow that necks down to an 18-inch overflow pipe and then down to the ground.
How do I calculate the maximum flow over a circular weir? My maximum head above the lip is 6-inches.
I was planning to calculate it as a broad crested weir.
Q=(2/3)(C1)(b)(SQRT(2g))H^(3/2)
C1 = 0.5 to 0.57
After the water goes over the weir it drops 150-feet by gravity, straight down, so I think my weir length is my limiting factor.
Any thoughts?
Thanks.
Chuck
How do I calculate the maximum flow over a circular weir? My maximum head above the lip is 6-inches.
I was planning to calculate it as a broad crested weir.
Q=(2/3)(C1)(b)(SQRT(2g))H^(3/2)
C1 = 0.5 to 0.57
After the water goes over the weir it drops 150-feet by gravity, straight down, so I think my weir length is my limiting factor.
Any thoughts?
Thanks.
Chuck





RE: Conical Weir
Q=CLH^(3/2)
C=3.2 to 4.6
Brater and King, (5-34) and table 5-2
RE: Conical Weir
For inward flow over a circular weir Lowenstein (Chem Eng., 61, 224 (Oct 1954)) gave the formula
W = 187.2 x L x (H^1.4)
where
W is flow rate lb/sec
L is length of wetter perimeter of the crest of the weir, ft
H is height of head above the crest, ft
I have seen simlar installations where the angle of the cone is quite shallow, and in that case your assumption of a broad crested weir may be better than a sharp crest. I would calculate the flows for the various different assumptions - i.e. straigh sharp weir, straight broad weir and circular weir and see what range I got.
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