17
4 Mounting
VEGAPULS 66 enamel • 4 … 20 mA/HART - four-wire
31954-EN-141215
ing reflections from the agitators are saved with the blades in different
positions.
Fig. 11: Agitators
Through the action of filling, stirring and other processes in the vessel,
dense foams which considerably damp the emitted signals may form
on the product surface.
If foams are causing measurement errors, the biggest possible radar
antenna should be used.
As an alternative, sensors with guided microwave can be used. These
are unaffected by foam generation and are best suited for such ap
-
plications.
By using a standpipe, the influence of vessel installations and turbu
-
lence can be excluded. Under these prerequisites, the measurement
of products with low dielectric constant (from 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.
Surge pipe
Make sure you provide the necessary upper vent hole in the surge
pipe. The hole must be aligned so that it and the polarisation marking
on the sensor flange are in the same plane (see illustration: "
Pipe
antenna system in a tank
").
Foam generation
Measurement in the
standpipe (surge or by-
pass tube)
