VEGA Capacitive electrodes EK Profibus PA - Manual (Page 16)

16 Capacitive electrodes EK - Profibus PA
Mounting
Lateral load
2 Mounting
2.1 Mounting instructions
General
Different mediums and measurement
requirements make different installation
positions necessary. Please note the
following points.
Lateral load
Make sure that the electrode is not subjected
to strong lateral forces. Mount the electrode
in a position in the vessel where no disturbing
factors such as e.g. stirrers, filling openings
etc. are present. This is especially important
for very long rod and cable electrodes.
In such cases, use a rod electrode for short
meas. distances, since a rod is usually more
stable. If, due to the length or the installation
position, a cable elctrode is necessary, the
electrode should not be fixed but simply
provided with a gravity weight to allow the
cable to more easily follow the product
movements. Make sure that the electrode
cable does not touch the vessel wall.
Pressure
If there is gauge pressure or underpressure
in the vessel, the mounting boss on the
thread must be sealed. Use the attached
seal ring. Check whether the seal ring is
resistant against the medium.
Insulating measures, such as e.g., covering
the thread with Teflon tape, can interrupt the
necessary electrical connection in metal
vessels. For this reason, ground the
instrument on the vessel.
Shortening the electrode
Fully insulated electrodes have fixed
dimensions which must not be modified in
any way. Any modification will destroy the
instrument.
Partly insulated cable or rod electrodes can
be shortened if necessary. The basic
capacitance of the electrodes is
compensated automatically at adjustment
time. Because of this, the electrodes can be
shortened by any desired amount.
Cable electrode EK 31 can also be
shortened. Loosen the two pins on the
gravity weight (hexagon socket) and remove
them. Pull the cable out of the gravity weight.
Extracting forces
In case of strong extracting forces, e.g. due
to material inflow or material slide, high tensile
loads can occur.