Ultrasonic level gauge/ ultrasonic level sensor blind zone problems and installation precautions

The Ultrasonic level gauge also called ultrasonic level sensor is a low-cost, easy-to-install level gauge with a wide range of applications: pool, tank level monitoring, river level, lake level, sewage depth, tank level, etc.

Principle of ultrasonic level gauge: The ultrasonic pulse sent out by the transmitter meets the surface of the measured medium and is reflected back, and the reflected echo is received by the same transmitter and converted into an electrical signal. Ultrasonic pulses travel at the speed of sound waves.

 

The blind zone of the ultrasonic level gauge is unavoidable in the measurement process. So, what is the blind zone of the ultrasonic level gauge? How did it come about?

 

Just like the human eye, when the object is very close to the eye, it cannot be seen clearly. This distance is called the blind spot. According to the working principle of the ultrasonic level gauge, the ultrasonic level gauge measures the liquid level according to the transmission and reception of ultrasonic waves. The speed of ultrasonic transmission in the air is fixed. The ultrasonic wave is emitted, and then the wave reflected from the liquid surface or the object surface is received, and the specific position of the liquid level can be calculated by controlling the timing from the start of transmission to the end of receiving the echo.\

Under normal circumstances, when the range is the same, the blind area of ​​the ultrasonic level gauge is proportional to the intensity of the transmitted wave. The stronger the transmitted wave, the stronger the received echo signal, but the larger the residual vibration and the larger the blind area. Conversely, the weaker the transmitted wave, the smaller the blind spot. In the case of the same transmitted wave intensity, the closer the detection distance, the stronger the received echo signal, and the larger the blind area of ​​the ultrasonic level gauge.

 

When the range is different, the blind zone is also different. If the range is small, the blind zone is small; if the range is large, the blind zone is large. But generally speaking, the blind zone of the ultrasonic level gauge is between 30cm-50cm.

 

on some special occasions, due to the limitation of space and installation conditions, the blind area of ​​liquid level measurement will be required to be small. At this time, the small blind area ultrasonic level gauge should be considered. The blind area is generally only 4-6cm, but its range is relatively small. only 60cm.

 

Through a specific analysis of the measurement accuracy and the reasons for the formation of the blind zone, the size of the blind zone of the ultrasonic level gauge is mainly related to the strength of the transmitted wave and the method of echo detection. Therefore, when installing the ultrasonic level meter, in order to ensure the accuracy of the measurement, the blind area of ​​the ultrasonic level meter must be taken into account, and the highest measured liquid level should not be higher than the blind area of ​​the ultrasonic level meter. When it comes to the blind spot, it mainly starts from the above two aspects.

 

Precautions for on-site installation of ultrasonic level gauge:

 

1. The wave emitted by the ultrasonic probe is a diffusion process, that is, there is a direction angle. Pay attention when installing it, otherwise, it may hit the protrusions on the pool wall or the edge of the channel. affect the measured value.

 

2 The installation position of the probe should try to avoid the position where the liquid level fluctuates violently, such as the inlet and outlet directly below.

 

3 If the wall of the tank wall is not smooth, the installation position of the instrument should be more than 0.3m away from the tank wall or the tank wall.

 

4. It is recommended to install a sun visor when the instrument is installed outdoors to prolong the service life of the instrument.

 

5. Wires and cable protection tubes should be sealed to prevent water accumulation.

 

6 Although the meter has its own lightning protection device, it is recommended to install a special lightning protection device at the inlet and outlet ends of the meter when the meter is used in a lightning-prone area.

 

7 When the instrument is used in a particularly hot and cold place, that is, when the ambient temperature may exceed the working requirements of the instrument, it is recommended to add high and low-temperature devices around the liquid level instrument.