Ultrasonic level meter is an excellent non-contact interface measurement equipment, suitable for petroleum, chemical, tap water, sewage treatment, water conservancy and hydrology, steel, coal mining, electricity, transportation and food processing industries. It is easy to install and operate, has wide applicability and low price. It is a high-quality and low-cost material and liquid level measurement equipment.

Its principle: Installed on the upper part of the container, under the control of the electronic unit, the probe emits a beam of ultrasonic pulses to the object to be measured. The sound wave is reflected by the surface of the object, and part of the reflected echo is received by the probe and converted into an electrical signal. The time from the ultrasonic emission to the re-reception is proportional to the distance from the probe to the object to be measured. The electronic unit detects this time and calculates the measured distance based on the known sound speed. The distance from the probe to the bottom of the tank - the distance from the probe to the liquid level = the actual liquid level or the material level height. The liquid level height is converted into a 4~20mA current signal and a 1~5V voltage signal output. Or it can be transmitted to the control center through 485 communication, Hart communication, and GPS communication. Since temperature has a great influence on the sound speed, the instrument should measure the ambient temperature and correct the sound speed.

Installation precautions for ultrasonic level meters when used on site

1. Vertical

When installing the transducer, ensure that the emitting surface of the transducer is parallel to the plane to be detected, so that the sound wave can be emitted vertically to the surface of the object to be measured. This can ensure the maximum energy return.

Tips: If there is steam in the on-site environment, it is easy to form water droplets on the surface of the probe, and the probe volume is much larger than the actual distance to be measured. Then it can be tilted about 3 degrees to avoid the influence of water droplets condensation.

2. Blind area

The distance from the highest liquid level to the surface of the ultrasonic level meter probe should be greater than the blind area of the probe.

It should be noted here that our blind area is measured under relatively ideal conditions. Therefore, if we install a closed tank, it is best to increase the blind area value by 20%. If a long conduit is used for installation because the liquid will stir, then the blind area value is also best increased by 20%. In order to avoid blind areas, we often use extended conduits to avoid blind areas. When using extended conduits for installation, the angle AOB must be guaranteed to be the sharp angle of the probe.

3. Tank wall and obstacles

If the tank wall is smooth and there is no material hanging when the liquid level is lowered, then most of the time it can be installed at a distance of 30 cm from the tank wall. If the tank wall is rough, the probe should be installed away from the tank wall. If the tank bottom is not flat, there may be mismeasurement at zero liquid level. If it is a conical bottom, you can consider installing the probe just above the top of the cone. For round crossbars, as long as the distance exceeds 1m and the diameter does not exceed 5cm, the impact is not great. Otherwise, try to avoid it. But for flat crossbars, if there is a right angle to the tank wall, try to avoid it.

4. There is stirring and fluctuation

If there is stirring or fluctuation, you can use an extended catheter for installation. The catheter is directly inserted into the bottom of the liquid level. The diameter of the catheter only needs to be larger than the radiation surface of the probe, but it is necessary to ensure that the inner wall of the catheter is smooth, and there is no material hanging during the liquid level rise and fall process, and the liquid inside the tube is consistent with the outside of the tube. If the large range is not suitable for installation with a catheter, you can reduce the range. The specific reduction depends on the size of the wave.