The hottest level sensor and its application

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Level sensors and their applications

level sensors can be divided into two categories: one is a continuous level sensor that continuously measures level changes; The other is the switch type level sensor for point measurement, i.e. level switch. At present, the switch level sensor is more widely used than the continuous level sensor. It is mainly used for threshold, overflow and idling prevention of process automatic control. Continuous level sensor is mainly used to predict product performance through simulation, continuous control and warehouse management. Sometimes it can also be used in multi-point alarm system. The following introduces several practical level sensors and their applications

l. capacitive level sensor

the capacitive level sensor has two conductor electrodes (usually the container wall is used as one electrode). The static capacitance changes due to the gas, fluid or solid between the electrodes, so it can be sensitive to the level. There are three types of sensitive elements, namely, rod-shaped, linear and plate-shaped. Its working temperature and pressure are mainly limited by insulating materials. The capacitive level sensor can be controlled by microcomputer to realize automatic sensitivity adjustment, and has the function of self diagnosis. At the same time, it can detect the damage of sensitive elements, the reduction of insulation, cable and circuit faults, etc, And can automatically report "We are glad to see that the business of the telecommunications industry is not only the growth of the improvement of rubber materials, but also the realization of highly reliable information transmission. Because the capacitive level sensor has no mechanical movable part, and the sensitive element is simple, the shape and structure are free to be large, and the operation is convenient, it is the most widely used level sensor.

2. It is floating in the automatic balance level sensor, which detects the balance float Measure the liquid level according to the change of buoyancy. It can be equipped with a microcomputer, which has the functions of self inspection, self diagnosis and remote transmission. It can be used to measure the liquid level of a large span with high precision

3. Generally, the pressure level sensor adopts the semiconductor capsule structure, and the metal sheet is used to bear the liquid pressure, which is transmitted to the semiconductor strain gauge through the sealed silicone oil conduction pressure to measure the liquid level. Due to the improvement of the performance of solid-state pressure sensors (piezoresistive bridge type) and the development of micro processing technology, pressure level sensors are more and more widely used. In recent years, the pressure level sensor with small volume, wide temperature range, good reliability and high precision has been developed. At the same time, its application range has been continuously expanded

4. Ultrasonic level sensor is a non-contact level sensor, which is widely used in many fields. Its working principle is that when it works, it emits a beam of ultrasonic wave to the liquid surface or powder surface, which is reflected by it, and then the sensor receives the reflected wave. If the sound speed is fixed, the distance from the absorber to the liquid level (powder surface) can be calculated according to the round-trip time of the sound wave, that is, the position of the liquid level (powder surface) can be measured. There are two kinds of sensitive elements, one is composed of coil, magnet and film, and the other is composed of piezoelectric magnetostrictive material. The former generates 10kHz ultrasonic wave, while the latter generates 20~40khz ultrasonic wave. The lower the frequency of ultrasonic wave, the smaller the attenuation with distance, but the reflection efficiency is also small. Therefore, the ultrasonic sensor used shall be determined according to the measurement range, material level surface condition and surrounding environmental conditions. High performance ultrasonic level sensor is controlled by microcomputer. Feature adjustment and function detection with compact hardware. It can accurately distinguish signal wave and noise, so it can measure the material level under any working condition of the agitator. In addition, it can also detect the level at high temperature or blowing, especially the level of high viscosity liquid and powder

5. The laser level sensor is a non-contact high-precision level sensor with excellent performance. Its working principle is the same as that of ultrasonic level sensor, except that the ultrasonic wave is replaced by light wave. The laser beam is very thin. As a level sensor, even if the level surface is extremely rough, the reflected beam is only widened to 20mm, but this is still within the range that the laser level sensor can receive. The laser level sensor generally uses near-infrared light. The laser emitted by the optical flow is processed by the semi transmission mirror. One part is input to the time transmitter as the reference signal, and the other part is processed by the optical system into a parallel beam with a certain width through the semi transmission mirror to irradiate on the object surface. The reflected wave arrives at the sensor receiving part and is converted into an electrical signal. Because the time from irradiation to acceptance is very short, the sampling circuit is expanded to the order of nanoseconds to facilitate signal processing and time measurement. The microcomputer is used for data processing, and the analog output signal of the digital display level value is changed, and then the software is used to detect the reliable part of the signal. If the measurement system fails, the alarm will be given. The sensor can be used to measure the liquid level of hot metal in sand mold of continuous casting equipment in iron and steel industry. At the same time, it can also be applied to narrow open containers and high-temperature, high-precision liquid level detection

in addition, in recent years, with the development of high technology, our machine can withstand the visits of the majority of users. There has been a digital intelligent level sensor, which is an advanced digital level measurement system. The measurement component technology is combined with the calculation function of microprocessor to make the level measurement instrument to the control instrument a full digital system. The comprehensive performance index and actual measurement accuracy of the digital intelligent level sensor are 3-5 times higher than those of the traditional analog level sensor. In short, with the development of sensor technology, the form of level sensor will be various, and its form should focus on non-contact. Its development direction is to further improve the overall performance through the wide application of high-tech electronic technologies such as microcomputer. At the same time, it will also develop in the direction of miniaturization, intelligence and multifunction

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