Potential Failure of Ultrasonic Liquid Level Gauge

The ultrasonic waves emitted by the ultrasonic level gauge are invisible to the human eye. In addition to the failure of the level gauge itself, there are some other reasons for the abnormal situations.

Ⅰ. Measuring while stirring will affect the accuracy of the ultrasonic level meter

1. Fault: No signal or severe data fluctuation.

2. Reason: The measuring distance of several meters mentioned by the ultrasonic level gauge refers to the calm water surface. For example, an ultrasonic level gauge with a range of 5 meters generally means that the distance to a calm water surface is 5 meters, but the actual distance from the factory will be 6 meters. In the case of stirring in the container, the water surface is not calm, and the reflected signal will be reduced to less than half of the normal signal.

3. Solutions:

(1) Choose a larger range ultrasonic level meter. If the actual range is 5 meters, then use a 10m or 15m ultrasonic level gauge to measure.

(2) If you don't change the ultrasonic level meter and the liquid in the container is not viscous, you can also install a wave guide, and place the probe of the ultrasonic level gauge in the wave guide to measure the height of the level gauge, because the liquid level in the wave guide is basically stable.

(3) Change the two-wire ultrasonic level gauge to a four-wire system.

Ⅱ. There is foam on the liquid surface of the ultrasonic level meter

1. Fault: The ultrasonic liquid level gauge is always searching, or it fails to detect ultrasonic wave.

2. Reason: The foam will absorb the ultrasonic wave, which causes the echo signal to be very weak. Therefore, when more than 40-50% of the surface of the liquid is covered with foam, most of the signal emitted by the ultrasonic level gauge will be absorbed, causing the level gauge to fail to receive the reflected signal. This problem has nothing to do with the thickness of the foam, but the area covered by the foam.

3. Solutions:

(1) Install the stilling wave tube. Place the probe of the ultrasonic level gauge in the stilling wave tube to measure the height of the level gauge, because there will be less foam in the stilling wave tube.

(2) Instead of using the ultrasonic level meter, you could use a radar level gauge for measurement, which can penetrate bubbles within 5 cm.