The significance of temperature compensation of ultrasonic level gauge

Ultrasonic level gauges are non-contact level measuring instruments controlled by a microprocessor. The ultrasonic wave of the ultrasonic level gauge is emitted by the probe (sensor and transducer), and the sound wave is reflected by the surface of the object and then received and converted into an electrical signal by the same probe, and the transmission time of the sound wave from emission to reception is used to calculate the probe to the liquid level to be measured. distance. The relationship between the distance value S and the speed of sound C and the transmission time T can be expressed by the formula: S=CxT/2.

Jiwei Uson-11 Ultrasonic Level Gauge Product Outline Drawing

Under atmospheric pressure, the propagation speed of ultrasonic waves in the air at room temperature is about 340m/s. The ultrasonic level gauge is used to measure the liquid level, which is based on the principle that the propagation speed C of ultrasonic waves in a certain medium is a certain value. measured. In fact, when the air temperature increases by 1°C, the speed of sound changes by about 0.6m/s. Therefore, if the speed of sound is calculated as a fixed value system, the measurement error of the liquid level will be very large. In order to meet the requirements of accuracy in industrial applications, the speed of sound must be corrected, and the method of sound speed correction mainly adopts the temperature compensation method.

Using temperature compensation for sound speed correction is to calculate the actual sound speed according to the approximate relationship between temperature and sound speed C=331.45+0.607*T(℃) or C=20.607*T1/2, so as to achieve the purpose of compensating the sound speed. The specific implementation method is to add a temperature sensor in the probe to measure the temperature change of the environment. When the ultrasonic level gauge is working, the ambient temperature value at that time is converted into a digital signal and transmitted to the single-chip computer, and then the single-chip computer calculates the actual sound speed at this temperature.

The significance of using the temperature compensation method for the ultrasonic level gauge is to help improve the accuracy of the system measurement and meet the requirements of industrial applications.

Because the ultrasonic level gauge adopts non-contact measurement, and the measurement is not affected by the density of the medium, dielectric constant, conductivity, etc., its application range is very wide, covering the water level measurement of rivers, lakes, and canals, as well as pools, troughs, and troughs. Measurement of sewage, oil and slurry such as tanks and tanks. At present, ultrasonic liquid level measurement technology plays an increasingly important role in more and more extensive fields. (The article is excerpted from: Please indicate the source for reprinting.)

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