Proper Installation of Ultrasonic Open Channel Flowmeter Prevents False Readings [Dayu Electronics]
Ultrasonic open channel flowmeter needs to be installed on the mounting bracket of a Parshall flume. A standard Parshall flume is verified by national authorities and has a reliable head-discharge relationship curve.
By measuring the water level at the inlet zone of the Parshall flume and combining it with the flume's dimensional settings, the instantaneous flow rate can be calculated. Over time, the cumulative flow is derived.
Why do some customers experience inaccurate readings, no signal, or wildly fluctuating data? Even when the water flow is stable, the flow reading may jump.
The first common issue is that the meter shows flow when there is none. This is likely due to incorrect installation height. This problem often occurs with Parshall flumes, especially sizes 1 to 4, because they come with a bracket for mounting the device. If the ultrasonic open channel flowmeter is mounted on this bracket, the ultrasonic waves may hit the side walls of the flume or the bracket itself. In such cases, either remove the bracket and lower the probe, or reposition the probe to avoid hitting the bottom of the probe. See Figure 4.
The second issue is data fluctuation. For instance, the normal reading is 200 L/s, but the display might show 200 L/s one second and 500 L/s the next. This can be caused by over-tightening the flange, leading to resonance from temperature changes at night. After adjusting the bracket to a height of 20 cm and changing the probe type to 1 to reduce signal strength, the false readings were eliminated.