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RBC Flume Accuracy

Clemens, Wahl, Box, and Replogle state the RBC flume’s accuracy to within +/-2%. However, practical considerations such as approach flow, installation, and dimensional tolerances make its free-flow discharge precision closer to +/-5%.  

RBC installations where the upstream / downstream / installation conditions are less than optimal or where the flume is out of dimension will exhibit accuracies less than above and may require field calibration.

RBC flumes that have experienced settling (or been installed at a slope) do not have corrections available and must be reset for accurate flow measurement.   

The above holds true for RBC flumes experiencing free-flow.  For installations where downstream conditions restrict the flow out of the flume, submergence may become a factor.  As submergence corrections are not available for RBC flumes, a submerged installation must either have the flume raised or the downstream conditions corrected.

RBC Flow

He = feet, Hm = mm

Flume Size



50 mm

657.9 (H +0.0025)1.853

0.001035 (H +0.75)1.853

75 mm

854.7 (H +0.0043)1.853

0.001347 (H +1.313)1.853

100 mm

1040 (H +0.0073)1.867

0.001514 (H +2.214)1.867

150 mm

1348 (H +0.0118)1.870

0.001929 (H +3.603)1.870

200 mm

1615 (H +0.0179)1.879

0.002189 (H +5.457)1.879

RBC Flume Flow Tables

Free-flow discharge tables for RBC flumes can be found in the Discharge Tables section.