To measure the flow of an open channel we have to make the flow pass through obstructions. The flow is measured from this obstruction like Weirs and Flumes. A special method used to measure the flow is using Open Channel Flow Meter other than pitot tube and measurement using float.
Weirs have a defined cross-section area and hence computation of discharge is simple. Weir used to maintain an upstream level or for measuring discharge
Weir should be build rigid, water tight normal to the flow direction. The site chosen for weir should have less chance of sediment growth. And we must avoid conditions for sedimenting sludges, weeds in the channel.
Flume is another flow measuring structure made along the flow channel. Flume makes flow constriction in a channel.Just like venturi, the flume is narrow constriction. So a unique stage-discharge relationship exists independent of the downstream condition.
Open Channel Flow monitor，using ultrasonic propagation in the air to measure the level of liquid height, and continue to liquid level information transmitted to the host, the host through the computing system, automatic measurement of instantaneous flow and cumulative flow and storage. With different built-in algorithmus, the product supports weirs or notches of different standards in various countries and can be widely used for measurement or monitoring of total water drainage. The measurement result is not affected by the water qulity, it can be connected with various systems and with GPRS wireless module, realize the industrial remote monitoring and control.