Ultrasound is a kind of mechanical wave (frequency between 10 and 100kHZ), and its transmission speed is related to the medium and is a function of medium temperature and pressure. The influence of temperature on the speed can be compensated by setting the temperature sensor in the probe, but because its working principle is based on the piezoelectric effect of the element, pressure compensation cannot be performed at present. Therefore, ultrasonic level gauges are not ideal for high temperature and high pressure applications.
Since the receiving of the reflected wave can be used only after the piezoelectric crystal is stopped, the emission of the ultrasonic wave is discontinuous. Taking into account the stop time of the piezoelectric crystal and the emission time corresponding to the period of the acoustic wave, the ultrasonic level meter has a measurement blind zone, which is the minimum distance from the probe to the highest level. Under normal circumstances, the larger the measurement range, the smaller the beam's emission angle, the lower the sound wave frequency, and the smaller the mechanical wave attenuation, the larger the blind area.