Accurate point level detection is crucial for ensuring safe and efficient industrial processes across all industries. The vibronic measuring principle offers a robust solution for reliably identifying whether liquids or bulk solids are present at a defined level, for example to prevent overfilling.
This technology operates using a piezoelectrically excited tuning fork that vibrates at its natural resonant frequency in air. When it comes into contact with a liquid, the oscillation is damped or in bulk solids, the resonant frequency shifts. These changes are precisely detected and converted into a switching signal for process control.
The vibronic measuring principle works independently of medium properties such as conductivity, density, pressure, or temperature. It is also unaffected by foam, turbulence, or bubbles, ensuring reliable operation even under challenging conditions.
Watch the video to learn how the vibronic measuring principle works.
Advantages of Liquiphant and Soliphant at a glance
- Universal measuring principle for liquids and bulk solids.
- Precise detection regardless of medium properties.
- Unaffected by foam, turbulence, or bubbles.
- Simple installation and operation.
- Robust design with minimal maintenance requirements.
The most varied media are filled into and drained from storage tanks every day. Examples are potable water, fruit juices, oils and fuels, acids, brines or even solids like grain, plastic pellets or powders. Since these media can have completely different properties, there are different measuring principles to detect them. For example, point level measurement in liquids or bulk solids according to the vibronic principle, called also tuning fork principle.
The tuning fork, which John Shore designed more than 300 years ago, served as a basis for the vibronic principle invented by Endress+Hauser in 1967. This principle uses the direct correlation between oscillation and damping in media. Let's have a closer look at how this measuring method works.
Vibronic instruments monitor point levels in tanks, containers and pipes. A sensor in form of a tuning fork is excited to its resonant frequency. The vibronic measuring principle in liquids is based on the resonant shift of a piezoelectrically excited oscillation system. There are two different piezoelectric drives, the Bimorph drive in standard instruments and the Stack drive in coated instruments.
The Bimorph drive consists of two disks: a piezo and a ceramic disk, which are connected to each other. At the same voltage the piezos are compressed and the ceramic disk is bent. At different voltages the piezos expand again. This causes the oscillations of the fork. The stack drive, however, stacks and fixes several piezo discs with changing polarization on top of each other.
The application of a respective alternating voltage also causes the piezos to oscillate. As the piezos expand, the membrane is bent to the outside. The ends of the tuning fork, which is attached to the membrane, are pushed apart. As the piezo contracts again, the membrane is bent to the inside. The ends of the tuning fork attached to it are pulled together. As the tines of the fork are covered in a tank as a liquid rises, the resonant frequency of the tuning fork changes.
The immersion into the liquid reduces the frequency. This frequency change is analyzed and converted into a switching signal. In solids measurement, only the piezoelectric stack drive is used. As the bulk solids cover the fork, the oscillation is damped. This change is the amplitude of the oscillation. The change is analyzed and converted into a switching signal.
The vibronic measuring principle of Endress+Hauser enables the point level detection unaffected by the physical properties of the medium, for example, conductivity, dielectric constant, density changes, pressure or temperature. Turbulences, the formation of foam or bubbling liquids do not impair the point level detection either.
We have an appropriate solution for any application. Endress+Hauser.
