Recently, an industrial plant needed an accurate means to measure flow from a tank. Since most commonly used flow equations for weirs rely on a sharp-crested weir plate, the thick tank sidewall presented an issue. We were uneasy with assumptions, no flow chart, and exactly how to convert level to flow rate. Too, windy conditions often created turbulence in this corner of the tank; further complicating initial attempts at flow measurement.
Instead, we chose to mount a 2.0’ H-flume. The H-flume has excellent resolution from just a few GPM to several thousand – we call it “from a trickle to a torrent”. A stilling well was attached to tranquilize the water surface at the Ha head measurement location.
After a little reprogramming, their existing flow meter started registering flow and reporting to the plant’s DCS system. A calculated staff gage allows operators to confirm accurate level measurement and conversion to flow rate.