I Different principles of application.
An ultrasonic level meter is a digital level instrument controlled by a microprocessor. In the measurement, pulsed ultrasonic waves are emitted by the sensor (transducer), and the sound waves are reflected by the surface of the object and then received by the same sensor and converted into an electrical signal. The distance from the transducer to the object to be measured is calculated from the time between the emission and reception of the acoustic wave. Due to the use of non-contact measurement, the measured medium is almost unlimited and can be widely used in a variety of liquid and solid material height measurements.
Ultrasonic level meters use sound waves and radar uses electromagnetic waves, which is the biggest difference between the two. Since ultrasonic penetration ability and directionality are much stronger than electromagnetic waves, this is the reason why ultrasonic detection is more popular nowadays.
The Radar Level Gauge utilizes a circuit design with a high-frequency microstrip line structure, where the internal circuitry generates microwave pulse signals at 25 GHz. Based on the design principle of the high-frequency waveguide, the microwave pulses are emitted from the end of the antenna through a PTFE transmitter. When the emitted pulse touches the surface of the measured medium, part of the energy is reflected and received by the same antenna. Through the principle of time dilation technique, the time interval between the transmitting and receiving pulses is calculated to further deduce the distance from the antenna to the surface of the measured medium.
II The application of different occasions
Due to the difference in the measurement principles of ultrasound and radar, they are used in different applications.
- The radar level meter is an electromagnetic wave, by the measured material dielectric constant, and ultrasonic waves are mechanical waves, by the measured density of the medium. So if the measurement of dielectric constant is very low, the measurement effect of radar level meter should be greatly reduced, which is not suitable for the use of radar level meter measurement.
- The measurement range of a radar level meter is much larger than that of an ultrasonic level meter. Radar emits electromagnetic waves, which can be measured without the help of propagation media. And ultrasonic waves are acoustic and mechanical waves, that need to spread with the help of propagation media. Therefore, ultrasonic level gauges can not be used in a vacuum, if the steam content is too high or the liquid surface has foam and other conditions.
The ultrasonic level meter has temperature limitations, generally, the temperature at the probe can not exceed 80 degrees, and the speed of the sound wave is greatly affected by the temperature. The ultrasonic level meter is greatly affected by the pressure, generally requiring 0.3MPa or less, because the sound wave relies on vibration to send out, and the pressure is too large when the sound components are affected. When the measurement environment is very foggy or dusty, the ultrasonic level meter can’t measure well.
In contrast, the radar is electromagnetic waves, not affected by the vacuum, and the medium temperature and pressure of the applicable range is very wide, with the emergence of high-frequency radar, the scope of its application is even more extensive, ultrasonic level meter is more restricted.
III. The two waves are emitted in different ways
- Ultrasonic waves are emitted through the vibration of the piezoelectric material, so the ultrasonic level gauge can not be used in higher pressure or negative pressure occasions, generally only used in atmospheric pressure vessels. While the radar level meter can be used in the process of high pressure.
- The radar launch angle than ultrasonic, in small containers or long thin containers are not recommended to use non-contact radar, generally recommended guided wave radar. The last is the problem of accuracy, of course, the accuracy of the radar is certainly higher than the ultrasonic wave, in the tank is certainly a high-precision radar, and will not choose the ultrasonic wave.
- The radar level meter has horn type, rod type, and cable type, and can be applied to different measurement conditions, so relative to the ultrasonic level meter, the radar level meter can be applied to more complex conditions.
- In terms of price, compared with the ultrasonic level meter, the radar level meter price is relatively high. Of course, some of the large range of ultrasonic prices are not low, such as the 6 to 70 meters range, a large range of radar level meter can not reach, only the ultrasonic level meter.
IV. Differences in measurement accuracy
Radar level meter and ultrasonic level meter measurement accuracy level is different, radar level meter accuracy is much higher than the ultrasonic level meter accuracy value. Therefore, the price difference between the two liquid level meters is also slightly higher.
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