Typical upstream distance is around 6 times the throat width.The sensor (ultrasonic, bubble tube, etc.) should be placed 2/3 of the distance of the throat width upstream from the beginning of the throat.

The formula for calculating flow rate for Parschall Flume is :take the square root of the cube of the height, in percent., to obtain percent of full flow.The full flow should be specified in the design of the Flume.A flow data chart should have been included if this is a manufactured flume, rather than a field fabricated unit.

Is this for influent, or effluent flow? If so, be aware that foam can sometimes create errors with certain ultrasonic sensors.

Does this help?

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