13
4 Mounting
VEGACAL 62 • Profibus PA
30025-EN-160331
The process fitting must be sealed if there is gauge or low pressure in
the vessel. Before use, check if the seal material is resistant against
the measured medium and the process temperature.
The max. permissible pressure is specified in chapter "
Technical
data
" or on the type label of the sensor.
Insulating measures, such as e.g. covering the thread with teflon tape,
can interrupt the necessary electrical connection with metal vessels.
For this reason, ground the probe on the vessel or use a conductive
seal material.
Metal vessel
Make sure that the mechanical connection of the probe to the vessel
is electrically conductive to ensure sufficient grounding.
Use conductive seals, such as those made of copper or lead, etc.
Insulating measures, such as covering the thread with Teflon tape,
can interrupt the necessary electrical connection with metal vessels.
For this reason, ground the probe on the vessel or use a conductive
seal material.
Non-conductive vessels
In non-conductive vessels, e.g. plastic tanks, the second pole of the
capacitor must be provided separately, e.g. in the form of a concentric
tube.
If possible, the capacitive probe should be mounted vertically or par-
allel to the counter electrode. This applies particularly to applications
in non-conductive products.
In cylindrical tanks, spherical tanks or other asymmetrical tank forms,
nonlinear level values are generated due to the varying distance to
the vessel wall.
Use a concentric tube in non-conductive products or linearize the
meas. signal.
If condensate forms on the vessel top, the run-off liquid can cause
bridging and hence measurement errors.
For this reason, use a screening tube or a longer insulation. The
length depends on the amount of condensate and the drain-off be-
haviour of the product.
Metric threads
In the case of instrument housings with metric thread, the cable
glands are screwed in at the factory. They are sealed with plastic
plugs as transport protection.
You have to remove these plugs before electrical connection.
NPT thread
In the case of instrument housings with self-sealing NPT threads, it is
not possible to have the cable entries screwed in at the factory. The
free openings for the cable glands are therefore covered with red dust
protection caps as transport protection.
Pressure/Vacuum
Vessel material
Vessel forms
Condensation
Cable entries - NPT
thread
Cable glands
