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technical article
Introduction to the dead zone of ultrasonic level gauge
2012-2-13 11:05:51

Blind zone of ultrasonic level meter: When transmitting ultrasonic pulse, ultrasonic level meter cannot detect reflected echo at the same time. Because the transmitted ultrasonic pulse has a certain time width and the sensor still has aftershock after transmitting the ultrasonic wave, the reflected echo cannot be detected during the period. Therefore, a short distance from the probe surface downward cannot be detected normally. This distance is called the blind zone. If the measured highest level enters the blind zone, the meter will not be able to detect it correctly and errors will occur. If necessary, the level gauge can be installed higher.


的盲区,根据量程的不同,盲区也不同。 The dead zone of the ultrasonic level gauge is different depending on the measuring range. The smaller the range, the smaller the blind zone, and the larger the range, the larger the blind zone. But generally it is between 30cm-50cm. Therefore, the blind spot must be considered when installing the ultrasonic level gauge. In special occasions, the blind zone is required to be small. At this time, a small blind zone ultrasonic level gauge can be considered, and the blind zone is generally only 4-6cm. But its range is very small, only 0.6m. In many areas of liquid level measurement, because of space constraints and installation conditions, ultrasonic level gauges with small blind spots are required. Market demand, ultrasonic level gauge and level gauge supplied by Anhui Secco Environmental Technology will meet your requirements. The working principle of the ultrasonic level gauge / level gauge is based on the transmission and reception of ultrasonic waves. The transmission speed of ultrasonic waves in the air is constant. The ultrasonic waves are emitted, and then the waves reflected from the liquid surface or the object surface are received, and the timing is controlled from the start of transmission to the end of receiving the echo. The timing of the transmission of ultrasonic waves in the air is determined. Distance L = speed (S) * time (T), because it is a round trip, the actual distance is half the distance L. The depth of the tank or the height of the tank is constant. The actual liquid level is the depth of the tank minus the distance measured by the ultrasonic wave, which is the height of the liquid level or the material level. As a result, ultrasonic or liquid level measurement is achieved. Ultrasonic level gauges have blind spots. Just like human eyes, blind spots are when objects are very close to the eyes, but they are not clearly visible. This distance is called a blind spot. The dead zone of the ultrasonic level gauge is different depending on the measuring range. The smaller the range, the smaller the blind zone, and the larger the range, the larger the blind zone. But generally it is between 30cm-50cm. Therefore, the blind spot must be considered when installing the ultrasonic level gauge. In special occasions, the blind zone is required to be small. At this time, a small blind zone ultrasonic level gauge can be considered, and the blind zone is generally only 4-6cm. But its range is very small, only 0.6m.

在发射超声波脉冲时,不能同时检测反射回波。 When the ultrasonic level gauge emits ultrasonic pulses, it cannot detect reflected echoes at the same time. Because the transmitted ultrasonic pulse has a certain time width and the sensor still has aftershock after transmitting the ultrasonic wave, the reflected echo cannot be detected during the period. Therefore, a short distance from the probe surface downward cannot be detected normally. This distance is called the blind zone. If the measured highest level enters the blind zone, the meter will not be able to detect it correctly and errors will occur. If necessary, the level gauge can be installed higher. When the ultrasonic level gauge is installed, the transmitter probe must be about 50 cm above the maximum liquid level. Only in this way can the accurate monitoring of the liquid level and the safety of the ultrasonic level gauge be ensured. In actual use, due to inadequate consideration during installation, the level gauge is flooded with water, causing the level gauge to be completely damaged. Features: low price, small size, light weight, can be used in food, chemical, semiconductor and other industries for liquid and bulk solid non-disconnected level measurement, can be used for remote level monitoring and pump control machinery installation should pay attention to: installation It should be perpendicular to the surface of the object to be measured. Avoid using it to measure foamy objects. Avoid installing it at a distance from the surface of the measurement object that is less than the blind zone distance. The blocking material does not meet the nozzle and the container wall. When detecting large solid objects, the orientation of the probe should be adjusted to reduce measurement errors.

工作时,高频脉冲声波由换能器(探头)发出,遇被测物体(水面)表面被反射,折回的反射回波被同一换能器(探头)接收,转换成电信号。 When the ultrasonic level gauge works, high-frequency pulse sound waves are emitted by the transducer (probe). When the surface of the measured object (water surface) is reflected, the returned reflected echo is received by the same transducer (probe) and converted into an electrical signal. . The time between the sending and receiving of pulses (moving time of the sound wave) is proportional to the distance from the transducer to the surface of the object. The relationship between the distance S of the sound wave transmission and the speed of sound C and the time T can be expressed by the formula: S = CT / 2 Installation of ultrasonic liquid level timer must consider the blind spot problem of ultrasonic liquid level meter. When the liquid level enters the dead zone, the ultrasonic transmitter cannot measure the liquid level, so when determining the range of the ultrasonic level meter, a margin of 50 cm must be left.