VEGA VEGAPULS 45 VBUS - Manual (Page 28)

28 VEGAPULS 42, 44 and 45 – VBUS
Mounting and installation
Sensor too close to the vessel wall
If the radar sensor is mounted too close to
the vessel wall, strong false echoes can be
caused. Buildup, rivets, screws or weld joints
superimpose their echoes onto the product
or useful echo. Please ensure sufficient dis-
tance from the sensor to the vessel wall.
In case of good reflection conditions (liquids
without vessel installations), we recommend
selecting the sensor distance so that there is
no vessel wall within the inner emission cone.
For products in less favourable reflection
environments, it is a good idea to also keep
the outer emission cone free of interfering
installations. Note chapter "3.1 General instal-
lation instructions".
Wrong orientation to the product
Weak measuring signals are caused if the
sensor is not directly pointed at the product
surface. Orient the sensor axis perpendicu-
larly to the product surface to achieve reliable
measuring results.
Foam generation
Conductive foam is penetrated by the radar
signals to different depths and generates a
number of single (bubble) echoes. The sig-
nals in the foam are also damped, like heat
radiation that tries to penetrate styrofoam.
Thick, dense, creamy foam, and especially
conductive foam, on the product surface can
cause incorrect measurements.
Foam generation
conductive
foam
Liquid
Direct sensor vertically to the product surface
Correct Wrong
Ladder
Ladder
Take measures to avoid foam, measure in a
bypass tube or use a different measuring
technology, e.g. capacitive electrodes or
hydrostatic pressure transmitters.
In many cases, VEGAPULS 54 radar sensors
with 5.8 GHz operating frequency achieve
considerably better and more reliable meas-
uring results in foam applications than type
40 sensors with 26 GHz technology.