VEGA VEGAPULS 56K - Manual (Page 14)

14 VEGAPULS 56K
22915-EN-041227
Make sure the required upper vent hole in
the surge pipe is aligned with the marking
hole in the intermediate flange (polarisation
direction of the radar signals).
As an alternative to a surge pipe in the ves-
sel, a pipe antenna system outside the ves-
sel in a bypass tube is also possible.
Please note that when measuring in a surge
or bypass tube, the max. measuring range is
reduced by 5 … 20 % (e.g. DN 50: 16 m
instead of 20 m and DN 100 only 19 m in-
stead of 20 m).
Align the sensor such that the type label lies
on one axis with the tube holes or the tube
connection openings. The polarisation of the
radar signals enables a considerably stabler
measurement with this alignment.
Surge pipe welded to
the tank Surge pipe in the socket
piece
Pipe antenna system in the tank
Vent hole
Marking
hole in the
intermedi-
ate flange
Deflector
max.
min.
Reference plane
Mounting and installation
Mounting directly on flat vessel top
Sensor directly on the vessel top
If the stability of the vessel will allow it (sensor
weight), flat mounting directly on the vessel
top is a good and cost-effective solution. The
top side of the vessel is the reference plane.
3.3 Measurement in standpipe
(surge or bypass tube)
General instructions
Measurement in a standpipe is preferred in
vessels which contain many installations, e.g.
heating tubes, heat exchangers or fast-run-
ning agitators. Measurement is then possible
when the product surface is very turbulent,
and vessel installations can cause no false
echoes.
Due to the concentration of the radar signals
within the measuring tube, even products
with small dielectric constants (
ε
r
= 1.6 up to
3) can be reliably measured in surge or by-
pass tubes. Note the following instructions.
Surge pipes which are open at the bottom
must extend over the full measuring range
(i.e. down to 0% level), as measurement is
only possible within the tube.
It is advantageous to mount a deflector at the
tube end. This enables the minimum level of
the product to be reliably detected. This is
particularly important for products with a
dielectric figure < 5.