transducer
•
sized by max. depth of flume
•
approach is preferably rectangular, matching width and depth for distance 3 to 5
times the depth of the flume.
•
flow range 100:1
•
may be installed in channels under partial submergence (ratio of downstream level to
head).
Typically: -1% error @ 30% submergence
-3% error @ 50% submergence
•
for rated flows under free flow conditions, the head is measured at a point
downstream for the flume entrance. Refer to the following table.
Flume Size Point of Measurement
(D ft) cm Inches
0.5 5 1-3/4
0.75 7 2-3/4
1.0 9 3-3/4
1.5 14 5-1/2
2.0 18 7-1/4
2.5 23 9
3.0 28 10-3/4
4.5 41 16-1/4
•
H flumes come with flat or sloping floor. Same flow table can be used as error is less
than 1%.
•
position the transducer such that it is centered over the flow at a minimum height of
30 cm (12") above the maximum head
point of
measurement
plan
front
side
D
Q
H FLUMES, P-40 = 3
(as developed by the U.S. Department of Agriculture, Soil Conservation Service)
PL-399 6 – 40
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