What are the differences between radar level gauges and ultrasonic level gauges? What are the measurement principles of these two types of gauges? What are the working conditions for radar level gauges and ultrasonic level gauges? What is the measurement accuracy of radar level gauges and ultrasonic level gauges? Let's explain these two types of level gauges with you below.

　　Radar level gauges use a transmit-reflect-receive operating mode. The antenna of the radar level gauge emits electromagnetic waves, which are reflected by the surface of the measured object and then received by the antenna. The time it takes for the electromagnetic wave to travel from transmission to reception is proportional to the distance to the liquid level. The relationship is as follows:

　　D=CT/2

　　Where D is the distance from the radar level gauge to the liquid level

　　C is the speed of light

　　T is the electromagnetic wave running time

　　The radar level gauge records the time the pulse wave takes, and since the transmission speed of the electromagnetic wave is a constant, the distance from the liquid level to the radar antenna can be calculated, thus determining the liquid level.

　　In practical applications, radar level gauges come in two types: frequency-modulated continuous wave and pulse wave. Level gauges using frequency-modulated continuous wave technology have high power consumption, require a four-wire system, and have complex electronic circuits. Level gauges using radar pulse wave technology, however, have low power consumption, can use a two-wire 24VDC power supply, are easy to achieve intrinsic safety, have high accuracy, and have a wider range of applications.

　　Ultrasonic uses sound waves, while radar uses electromagnetic waves; this is the biggest difference. Moreover, ultrasonic waves have much stronger penetration ability and directionality than electromagnetic waves, which is why ultrasonic detection is now more popular.

　　Main application differences:

　　1. Ultrasonic accuracy is not as good as radar.

　　2. Radar is relatively more expensive.

　　3. When using radar, the dielectric constant of the medium must be considered.

　　4. Ultrasonic waves cannot be used in vacuum, high steam content, or foamy liquid level conditions.

　　5. The radar measurement range is much larger than that of ultrasonic waves.

　　6. Radar has horn, rod, and cable types, and can be applied to more complex working conditions compared to ultrasonic waves.

　　We generally refer to sound waves with frequencies exceeding 20kHz as ultrasonic waves. Ultrasonic waves are a type of mechanical wave, which is a propagation process of mechanical vibrations in an elastic medium. Its characteristics are high frequency, short wavelength, small diffraction phenomenon, good directionality, and the ability to become a ray for directional propagation. Ultrasonic waves have very little attenuation in liquids and solids, so they have strong penetration ability, especially in opaque solids, where ultrasonic waves can penetrate tens of meters. When they encounter impurities or interfaces, there will be significant reflection. Ultrasonic level measurement utilizes this characteristic.

　　In ultrasonic detection technology, regardless of the type of ultrasonic instrument, it is necessary to convert electrical energy into ultrasonic waves and emit them, then receive them and convert them back into electrical signals. The device that performs this function is called an ultrasonic transducer, also known as a probe. As shown in the figure, the ultrasonic transducer is placed above the liquid to be measured and emits ultrasonic waves downwards. The ultrasonic waves pass through the air medium and are reflected when they encounter the water surface. They are then received by the transducer and converted into electrical signals. After the electronic detection part detects this signal, it converts it into a level signal for display and output.

　　According to the principle of ultrasonic wave propagation in a medium, if the pressure, temperature, density, and humidity of the medium are constant, the speed of ultrasonic wave propagation in that medium is a constant. Therefore, when the time required for the ultrasonic wave to travel from emission to reflection from the liquid surface and reception is measured, the distance traveled by the ultrasonic wave can be calculated, and the level data is obtained.

　　Ultrasonic waves have a blind zone. When installing, the distance between the sensor installation position and the measured liquid must be calculated and reserved.