Vega VEGAPULS 62 Operating Instructions Manual page 22

Foam generation
Measurement in the
standpipe (surge or by-
pass tube)
VEGAPULS 62 - 4 ... 20 mA/HART
Fig. 13: Agitators
Through the action of filling, stirring and other processes
in the vessel, dense foams can be generated on the
product surface which damp the emitted signal consi-
derably.
If foams can cause measurement errors, biggest
possible radar antennas and low frequency radar
sensors, e.g. VEGAPULS 65/66 (C-band) should be
used.
VEGAFLEX sensors with guided microwaves are not
influenced by foam generation and are particularly
suitable for such applications.
By the use of a standpipe, influences of vessel
installations and turbulence can be excluded. Under
these requirements, the measurement of products with
low dielectric values (from DK value 1.6) is possible.
Surge or bypass tubes must extend all the way down to
the requested min. level, as measurement is only
possible within the tube.
Mounting
21