Levelprox series sensors of the hottest Turck

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The levelprox series sensors of Turck are used for liquid level detection in the industry.

there are two main methods for liquid level detection. In addition to the float type or tuning fork type sensor, there is also a detection device that does not need to be in direct contact with the detected liquid. This special sensor can detect the liquid level of its internal liquid through the metal wall

turck's levelprox series sensors use high-frequency ultrasound to achieve this detection. The new T50 sensor has two working modes to meet the needs of a wider range of applications

liquid level detection in industry

liquid level detection is very important for many automatic control schemes in today's industrial field. The choice of sensors is as diverse as its application. The key to select the correct sensor is to consider the relationship between the sensor and the measured medium. Most level control sensors need to be in contact with the measured medium. These products include float switches, electrodes and tuning fork level sensors. However, in some industrial occasions, direct contact between the sensor and the measured medium is not allowed, such as the food and pharmaceutical industries. To meet stringent hygiene standards, the sensor must be completely sealed in a container. In addition, all parts in contact with the medium will also encounter the same problems, such as the material of the inner wall of the container and its surface finish. Such sensors are also affected by the agitator. In addition, the liquid level sensor in contact with the medium will also encounter problems during repair and maintenance. When the sensor needs to be replaced, the container has to be opened, resulting in production interruption

the ultrasonic sensor that uses air as the transmission medium to detect the liquid level directly above the liquid does not need to contact the measured liquid, but its ultrasonic transducer still needs to be installed in the container. As a result, the materials of such devices are difficult to meet the requirements of the food industry like those of contact detection equipment

the capacitive sensor can detect the liquid level through the vessel wall. However, the stainless steel containers often used in the food industry can not be penetrated by the electric field of capacitive sensors

the most ideal liquid level detection device for the food and pharmaceutical industries should be able to detect the internal medium through the outer wall of the stainless steel container. In addition, it should also be able to be easily installed on the outer wall of the container, with easy maintenance and reliable performance. Turck's "levelprox" series products provide a simple and reliable liquid level detection scheme that can meet all the above requirements. The unique dual working mode makes its application scope broader

working principle

there are many ways to use ultrasonic wave to detect the liquid level through the outer wall of the container. However, all the technologies are based on high-frequency ultrasonic pulse, which is coupled to the outer wall of the container through coupling glue. In the reflection mode, the reflected echo of the container wall on which the sensor is installed will be detected and calculated

this pulse will propagate in the vessel wall until it reaches the inner surface of the vessel wall. If the container is filled with gas, the sound wave will be almost completely reflected back to the sensor. At this time, it will be reflected again and the pulse will be reflected back to the inner surface of the container, and so on. If the container is filled with liquid, part of the sound wave will be absorbed by the liquid. The absorption of sound wave will lead to two results: the anti monofilament must be quenched after leaving the machine head to make it become amorphous, and the reflection wave disappears, and part of the ultrasonic wave propagates to the opposite inner wall of the container through the liquid. The new levelprox series sensor lpre-t50 can use the above two effects to generate switching signals

reflection mode

in this mode, the reflection of supergenerated wave pulse will be calculated. The longer the reflection, the less liquid in the container. A brief reflection indicates that the container is full. In this mode, the reflected echo of the inner surface of the container where the sensor is installed will also be calculated, so the situation inside the container is no longer important

this method has special advantages for the detection of heterogeneous media (mixed or containing large bubbles). This mode is also the best choice if a mixing device is installed. However, the reflection method can not be used for those cases where there is residue attached to the inner wall of the container in the empty state. Since the reflected echo will be weakened by even a thin layer of medium, it will cause the sensor to incorrectly indicate that the container is full

echo mode

echo mode will calculate the ultrasonic wave propagating in the liquid and the echo reflected from the inner wall of the opposite container. If the ultrasonic pulse hits the inner surface of the container nearly vertically, the echo will return along the same path and be detected by the sensor. In this mode, the liquid containing large bubbles or the use of a stirring device will affect the detection. If the echo has sufficient strength when reaching the sensor, the sensor indicates that the container is full. If the echo is too weak, the sensor indicates an empty state. Even if the medium is attached to the inner wall of the container to enhance gas exchange, it can be correctly indicated

adapt to specific installation environment

whether echo mode is adopted, this technology can produce attractive packaging product type or reflection mode. The type of container, the installation position of sensor and the characteristics of the measured liquid are all key factors. Levelprox products need to learn the sound wave with/without liquid before detecting the liquid level. Therefore, in the teaching mode of the sensor, the empty and full states of the container must be taught by pressing the teaching button. Levelprox will then automatically adapt to the surrounding acoustic environment. Depending on the standard curve detected in the teaching mode, the corresponding output signal is given. The same method can also be used to detect incorrect or poor coupling with the vessel wall. This error is indicated by a red LED and an alarm output


the working mode of lpre-t50 levelprox series sensor can be selected through dip switch: reflection mode or echo mode. You can also select the normally open/closed mode of the switch through dip, lock the teaching button, and set the on/off delay. In echo mode, the reflected echo from the inner wall of the opposite container will be calculated


the sensor can be conveniently installed on the outer wall of the container through the three jaw snap ring, which is widely used in the food industry. Snap ring adapters can be welded or pasted on the outer wall of the container. Then insert the sensor into the adapter, put on the snap ring sealing washer, and finally fix it in place through the snap ring. The sealing gasket can isolate the sensor and the external environment, so as to ensure its hygiene. The head of the ultrasonic transducer is elastically supported to ensure proper pressure. During correct installation, no matter what the diameter of the container is, it shall be ensured that the sensor is tightly attached to the outer wall of the container with a certain prestress

the coupling medium is silica gel with medical hygiene. Ultrasonic wave can be well coupled to the outer wall of the container, and it can maintain its viscosity and non-toxic even at high temperature

more applications

levelprox is an ideal sensor for detecting liquid level through metal walls. It can be used not only in the food industry, but also in systems and mechanical engineering. For example, it is used to indicate the empty/full status of paint containers, waste water and hydraulic oil tanks. Since the paste installation method is available, the later maintenance and adjustment can be easily completed. The sensor can be disassembled and assembled at the existing installation position. In addition, the modification of the operating parameters of the switching point can also be 3 Plastic tensile testing machine: the tensile strength of plastic is greater than that of rubber. It is realized by simply repositioning the sensor. In the future, there will be more shapes and electrical designs to enrich the levelprox product family. (end)

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