Level Measurement
Level sensors are basically divided into
two different measuring systems. One system
functions on the basis of propagation time
measurement of an airborne ultrasonic signal
sent out and then reflected by the stored goods.
The particular advantage of this system is
that the level of solids in silos can also
be measured as this method operates on a
"non-contact" basis. A disadvantage of this
measuring technique is that the accuracy of
the measurement depends on the reflection
properties of the stored materials. The
received signal is dependent on part of the
radiated wave reaching the transducer
again. If the wave front is scattered
too much or absorbed by the stored materials, no
useful measurement is possible. The second
measuring principle used for level sensing
are the so-called immersible transducers.
The self-resonant frequency of a metal
tuning fork is excited by a piezoceramic. This self-resonant
frequency depends on the surrounding medium.
If for example the tuning fork is immersed
in a liquid or a powder, the resonant frequency
of the system will change. This change in
frequency is detected by the evaluating
electronics. The disadvantage of this system
is that no analog measurement is possible. The
sensor only informs whether a particular level
has been exceeded or not reached. This drawback
can be overcome by positioning several of these
sensors at different levels in the tank. The
advantage of the system is that the existing
charge is very reliably detected and the sensor
is largely unsusceptible to interference.
Designs: Round disk, perforated disks other special forms
Material: SONOX® P 4, SONOX® P 5