VEGA VEGAPULS 81 - Manual (Page 48)

48 VEGAPULS 64 and 81
Wrong directing to the product surface
A directing of the sensor which does not point
to the product surface will cause a weak
measuring signal. If possible direct the sensor
axis vertically to the product surface, to reach
optimum measuring results.
Mounting and installation: Installation fault
Sensor too close to the vessel wall
If the radar sensor is mounted too close to the
vessel wall, strong interfering signals can be
caused. Build-up, rivets, screws or weld joints
superimpose their echoes to the useful signal
or useful echo. Hence note a sufficient dis-
tance of the sensor to the vessel wall.
In case of good reflection conditions (liquids
without vessel installations) we recommend
you select the sensor distance so that there is
no vessel wall within the inner emission cone.
For liquids with worse reflection conditions it is
useful that there are also no interefering instal-
lations within the outer emission cone. Note
chapter “2.1 General installation instructions“.
Foam generation
Strong, dense and creamy foam on the prod-
uct can cause faulty measurements. Provide
measures to avoid foam or measure in a by-
pass pipe. Check if necessary the use of
another measuring principle e.g. capacitive
electrodes or hydrostatic pressure transmit-
ters.
Direct sensor vertically to the product surface
Correct Wrong
VEGAPULS 81 on a surge pipe: The polariza-
tion direction is in line with the casting nose.
The sensor must be directed with the castin
nose to the rows of holes or openings
Casting nose
Ladder
Correct Wrong