VEGA Capacitive electrodes EK … with signal conditioning instrument - Manual (Page 18)

18 Capacitive electrodes EK with signal conditioning instrument
Mounting
Fig. 2.1 Lateral load
2 Mounting
2.1 Mounting instructions
General
Different mediums and requirements to the
measurement require various installations.
Hence the following instructions should be
noted.
Length of the level electrode
Note when ordering the electrode, that the
electrode must be sufficiently covered ac-
cording to the electrical features of the me-
dium (DK-value).
E.g. an electrode for level detection in oil
e
r
~ 2) requires a considerably higher cover-
ing than in water (
e
r
~ 81).
Lateral load
Note that the electrode is not subjected to
strong lateral forces. Mount the electrode in a
position in the vessel where no interfering
influences such as e.g. stirrers, filling open-
ing etc. occur. This is mainly valid for very
long rod and cable electrodes.
Extraction forces
In case of strong extraction forces e.g. dur-
ing filling or settling of solids, high tensile
loads can be caused.
In these cases use for short measuring dis-
tances a rod electrode, as a rod is generally
more stable. If due to the length or the mount-
ing position a cable electrode should be
necessary, the electrode should not be
strained, but only equipped with a gravity
weight as then the cable can more easily
follow the product movements. Note that the
electrode cable does not touch the vessel
wall.
Pressure
In case of gauge or low pressure in the ves-
sel, the mounting boss must be sealed at the
thread. Use the attached seal ring. Check if
the seal ring is resistant against the medium.
Isolating measures such as e.g. the covering
of the thread with Teflon tape can interrupt the
electrical connection in case of metal vessels.
Hence earth the electrode on the vessel.