Ultrasonic Level Measurement

The most widely used principle of level measurement is based on propagation time measurement of air ultrasound pulse, emitted and then reflected by the filling medium. The piezo transducers are placed outside the medium to be detected and work as a transmitter and receiver. They send ultrasound pulses that are reflected by the filling medium. The required propagation time is a measure of the distance traveled in the empty part of the container.



Noncontact Level Measurement

This method also allows noncontact measurements, in which the filling level of liquids, but also of solids, e.g. in grain elevators, can be measured through distance measurement. The resolution or accuracy depends on how well the ultrasonic pulse is reflected by the respective surface.



  • Noncontact measurement
  • No contamination of the filling medium or of the sensors




Level Measurement Using Submersible Transducers or Tuning-Fork Sensors

Filling levels can also be measured using so-called submersible transducers or tuning-fork sensors. This method uses piezo elements as level switches. They are placed at different container heights.

The piezo transducers excite a tuning fork at its natural frequency. When in contact with the medium to be measured, the resonant frequency shifts. This method is very reliable and independent of the type of filling medium.


  • Robust measurement device
  • Measurement independent of the type of filling medium



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Success Story: PI Ultrasonic Piezo Elements for Sensor Applications

From Level Measurement to Adaptive Systems Technology
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