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# Significance of Temperature Compensation to Ultrasonic Level Meter

The propagation speed of ultrasonic wave is easily affected by air temperature, humidity, pressure and other factors, among which temperature has the greatest influence. Therefore, in order to obtain more accurate measurement results, it is necessary to compensate the temperature of ultrasonic level meter.

At present, many ultrasonic level meters in the market are with the function of "temperature compensation". So why do ultrasonic level meters need temperature compensation? Where is temperature compensation used?

It should be explained from the principle of ultrasonic level measurement.

## 1. Measuring principle of ultrasonic level meter

Ultrasonic level meter uses the time difference between sound wave transmission and reception, and the sound wave propagation speed to calculate the liquid level height. Ultrasonic level meter adopts non-contact measurement technology, which can be stably and reliably applied to continuous liquid level measurement of various open storage tanks such as sewage pond, water conservancy and hydrology and industrial wastewater.

## 2. The relationship between sound velocity correction and temperature compensation of ultrasonic level meter

At atmospheric pressure and normal temperature, the propagation speed of ultrasonic wave in air is about 340 m/s. In the process of measuring liquid level by ultrasonic liquid level gauge, it is based on the principle that the propagation speed C of ultrasonic wave is a certain value in a certain medium.

However, in practice, when the air temperature rises by 1, the sound speed of ultrasonic wave will change by about 0.6 m/s. Therefore, if the sound velocity is calculated as a fixed value system, the error of ultrasonic level measurement will be very large.

Therefore, in order to meet the precision requirements in industrial applications, the sound velocity must be corrected, and the method of sound velocity correction mainly comes from the temperature compensation method.

Using temperature compensation to correct sound velocity is to calculate the actual sound velocity according to the approximate relationship between temperature and sound velocity, so as to compensate the sound velocity. C=331.450.607 * T () or C=20.607*T1/2

It is realized by adding a temperature sensor inside the probe to measure the temperature change of the environment. When the ultrasonic level meter works, the ambient temperature at that time is converted into a digital signal and transmitted to the MCU, and then the MCU calculates the actual sound velocity at that temperature.

## 3. Significance of temperature compensation to ultrasonic level meter

The significance of temperature compensation to ultrasonic level meter is to improve the accuracy of ultrasonic level measurement and meet the requirements of industrial application.

Ultrasonic level meter adopts non-contact measurement and is not affected by medium density, dielectric constant and conductivity. Therefore, it has a wide range of applications, covering the water level measurement of rivers, lakes and canals, as well as the measurement of sewage, oil, mud and other industries such as tanks and canals.

Facing these different environments, working conditions and media, the temperature compensation function of ultrasonic level meter is particularly critical to obtain accurate ultrasonic level measurement results.

At present, with the continuous maturity of technology, ultrasonic level measurement technology plays an increasingly important role in more fields.