KROHNE BM 70 A Installation And Operating Instructions Manual page 20

An antenna extension should be added if the antenna does not project out of the fitting:
Antenna extensions are available from 100 to 2000 mm (3.94" to 78.74") in steps of 100 mm (3.94").
Several extensions can be joined up:
Exception:
When the tank fitting is sy mmetrical, the antenna may end in the fitting so as to enlarge the
measuring range (minimum dead zone to tank cover, see Sect. 3.3 "block distance" and Sect. 5.2
"error of measurement"):
Narrow tank fitting
If the inside diameter of the fitting is smaller than the diameter of the antenna, and the fitting is
accessible from inside the tank for mounting purposes, the antenna with extension can be mounted
from the inside (not for versions made of titanium or tantalum). The antenna extension should be
about 100 mm (3.94") longer than the height of the fitting.
Installation and operating instructions BM 70 A/P
Tank nozzle
Tank nozzle
Antenna
extension
Tank nozzle
Antenna
extension
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