1. Sound waves are mechanical waves, which will be reflected at the interface with large density change (gas-liquid-solid). Sound wave propagation depends on medium. Temperature and pressure have great influence on measurement, so temperature compensation is needed. Ultrasonic liquid level meter is generally not suitable for high temperature or pressure measurement. First of all, the ultrasonic liquid level meter is with a temperature limit. The temperature at the probe should not exceed 80℃. The speed of sound wave is greatly influenced by temperature. Secondly, the ultrasonic liquid level meter is greatly influenced by pressure. Generally, work environment of ultrasonic liquid level meter is required to be within 0.3MPa, because ultrasonic waves are emitted by the vibration of piezoelectric substances, and the sounding parts will be affected when the pressure is too high.
2. Radar level meter is not suitable for measuring environment with heavy fog or dust. The radar probe sends out high-frequency pulses and propagates along the cable. When the pulses meet the material surface, they are reflected and received by the receiver in the instrument, and the distance signals are converted into level signals. As detection signal, electromagnetic is reflected at the interface where the dielectric constant changes. Electromagnetic wave can propagate in vacuum, which is basically not affected by temperature and pressure changes. Therefore, radar level meter is suitable for high-temperature and high-pressure occasions, and is not suitable for measuring media with very low dielectric constant.
Radar level meter uses electromagnetic waves, which cannot be affected by vacuum degree. It has a wide range of application to medium temperature and pressure. The appearance of high frequency radar makes its application more extensive. Therefore, radar is a very good choice in level measurement.
1. The measuring range of radar is much larger than that of ultrasonic wave. The emission angle of radar is larger than that of ultrasonic wave, so it is not recommended to use non-contact radar in small containers or slender containers. Guided wave radar is generally recommended.
2. There are horn type, rod type and cable type of radar level meters. Compared with ultrasonic liquid level meters, radar level meters can be applied to more complex working conditions.
3. Ultrasonic wave is not as accurate as radar, so high-precision radar is used on storage tank, instead of ultrasonic wave.
4. The relative price of radar is higher. Under normal circumstances, the price of ultrasonic liquid level meter is lower than that of radar level meter. Of course, the prices of some ultrasonic liquid level meters with large range are also very high, such as the range of 6 ~ 70 meters. Radar cannot reach it, so we can only choose ultrasonic waves.
5. You should consider the dielectric constant of medium when using radar level meter.
6. Ultrasonic liquid level meter cannot be applied to working conditions such as vacuum, high steam content or foam on liquid surface.