Vega VEGAPULS 66 Operating Instructions Manual page 19

Measurement in the
standpipe (surge or by-
pass tube)
VEGAPULS 66 • 4 ... 20 mA/HART - two-wire
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.
Note:
Measurement in a standpipe is not recommended for extremely
adhesive products.
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").
Fig. 13: Pipe antenna system in a tank. The vent hole in the surge pipe must be
in one plane with the polarisation marking on the sensor.
1 Marking of the polarisation direction
2 Vent hole max. ø 5 mm (0.2 in)
If possible, the diameter of the sensor antenna should correspond
to the inner diameter of the tube. With VEGAPULS 66 this is approx.
50 mm (1.969 in) depending on the antenna. The sensor can be used
with tube diameters between 50 ... 250 mm (1.969 ... 9.843 in).
Bypass pipe
As an alternative to the surge pipe in the vessel, a tube system out-
side of the vessel is possible as a bypass tube. Select during setup
the function "Bypass tube".
Align the sensor in such a way that the polarisation marking on the
sensor flange is in the same plane as the tube holes or the tube con-
nection openings (see illustration: "VEGAPULS in a bypass tube").
max.
1
2
min.
4 Mounting
19