VEGA VEGAPULS 43 Profibus PA - Manual (Page 20)

20 VEGAPULS 43 – Profibus PA
Seals on tube connections and tube ex-
tensions
Microwaves are very sensitive to gaps in
flange connections. If connections are made
without proper care, distinct false echoes as
well as increased signal noise can result.
Observe the following points:
• The applied seal should correspond to the
tube inner diameter.
• If possible, conductive seals such as con-
ductive PTFE or graphite should be used.
• There should be as few seal positions as
possible in the guide tube.
Flange connections on bypass tubes
Adhesive products
With non-adhesive or slightly adhesive prod-
ucts, use a surge pipe with a nominal width of
e.g. 50 mm. VEGAPULS 43 radar sensors
with 26 GHz technology are for the most part
insensitive to buildup in the measuring tube.
Nevertheless, buildup should not block the
measuring tube.
For products with somewhat heavier buildup,
the use of a DN 80 to max. DN 100 standpipe
or surge pipe can make measurement possi-
ble despite buildup. But with extremely adhe-
sive products, measurement in a standpipe
is not possible at all.
Mounting and installation
Guide tube in existing surge or bypass tubes
Extended guide tube
Guide tube
To increase the min. distance, the guide tube
can project out of the surge or bypass tube.
This can be done by welding a flat welding
flange on the outside of the extended guide
tube. In both cases, an appropriate breather
hole is necessary.