The common method of measuring flow through an open channel is to measure the height or HEAD of the liquid as it passes over an obstruction (a flume or weir) in the channel.

Using ultrasonic level technology, Open channel flow meters include a non-contacting sensor mounted above the flume or weir.

By measuring the time from transmission of an ultrasonic pulse to receipt of an echo, the water level or “Head” is accurately measured.

Flumes and weirs are specially designed channel shapes that characterize the flow of water.

Common types are Rectangular Weirs, V-Notch Weirs, Parshall flumes and Palmer Bowlus flumes.

The choice of flume or weir type depends on the application: flow rate, channel shape and solids content of the water.

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## 2 comments

how to calculate open channel flow from parshall flume data ?

Good day! We are working on a project study that will prove Bernoulli’s Principle. Do we need to place two ultrasonic level sensors before and after it passes the weir? Where is the right place of the sensor for the second weir?