Level Measurement

Vibration fork point level switch

Vibration sensing is only suitable for point measurement. The vibration switch working principle is based upon detecting the change in harmonic vibration frequency of the sensing element as a result of the presence of the target media.



The vibration switch consists of an oscillating or tuning fork which is made to resonate in the air. The turning fork is installed in the tank at a level which the level is to be sensed. The electrically simulated vibration fork vibrated at a particular frequency. The resonance of the fork is caused by the piezoelectric crystal. Another piezoelectric crystal measures the frequency of the vibration.

When the level of liquid in the tank increases the fork will be covered by liquid. The resonance frequency will be reduced when the fork is brought into contact with the product because the dambing effect is produced. The change in resonance frequency is measured by the piezoelectric sensors and which is amplified to measure.




The change in measure activates alarming systems. The type of fork used and its resonant frequency depends on the material to be measured.


  • Wide range of applications
  •  Inexpensive
  • No adjustment or maintenance required


  • Grain limited to 10mm in size
  • Same limitation for particles suspended in liquids
  • Vibration level switches are limited to point or level detection


Instrumentation Engineer

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