VEGA VEGAPULS 41 4 … 20 mA; HART compact sensor - Manual (Page 23)

VEGAPULS 41 – 4 … 20 mA 23
26620-EN-041227
Pipe antenna: The surge pipe open to the bottom
must have a ventilation or equalisation hole at the
upper end
Correct Incorrect
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 series
40 sensors with 26 GHz technology.
Standpipe installation mistakes
Pipe antenna without ventilation hole
Pipe antenna systems must be provided with
a ventilation hole on the upper end of the
surge pipe. If this hole is absent, incorrect
measurements will result.
Foam generation
Conductive
foam
Liquid
Mounting and installation
If there are good reflection conditions (liquids
without vessel installations), we recommend
locating the sensor where there is no vessel
wall within the inner emission cone. For prod-
ucts in less favourable reflection environ-
ments, it is a good idea to also keep the outer
emission cone free of interfering installations.
Note chapter "3.1 General installation instruc-
tions“.
Foam generation
Conductive foam is penetrated to different
depths by the radar signals and generates a
number of individual (bubble) echoes. At the
same time, the signals are damped in foam,
similar to the way heat radiation is damped
by Styrofoam. Thick, dense, creamy and
conductive foam can cause incorrect meas-
urements.
Provide preventative measures against foam
or measure in a bypass tube. Check, if nec-
essary, the possibility of using a different
measuring technology, e.g. capacitive elec-
trodes or hydrostatic pressure transmitters.