VEGA VEGAPULS 81 - Manual (Page 32)

32 VEGAPULS 64 and 81
Mounting and installation
4 Mounting and installation
4.1 General installation instructions
Measuring range
The reference pane for the measur-
ing range of the radar sensors is
always the lower part of the sensor.
The measuring range of both instru-
ment series (VEGAPULS 64 and
VEGAPULS 81) is generally
0 … 20 m. Optionally sensors with a
measuring range of 0 … 35 m can
be supplied. For measurements in
surge or bypass pipes (pipe an-
tenna) the max. measuring distance
is reduced by appr. 20%. Please
note for measurements where the
products are filled up to the sensor
flange, that build-up on the antenna
can cause faulty measurements.
Measuring range (operating range) and maximal
measuring distance
Emission cone of a horn antenna on the
DN 100 flange
full empty
18 m
2 m
Measuring range
max. measuring distance 20 m
(optionally 35 m)
0
10 m
20 m
30 m
0 m
35 m
30°
40°
100%
50%
9,4 9,4 12 12
m
5,3 5,3
Measuring
distance
Emission cone and false reflections
The radar signals are focused by the antenna
system. The signals leave the antenna, similar
to a light beam of a headlight, in the form of a
cone. This emission cone depends on the
antenna used.
Each object in this emission cone causes a
reflection of the radar signals. Especially dur-
ing the first meters of the emission cones,
pipes, struts etc. cause strong false reflec-
tions. E.g. in a distance of 6 m the false signal
of a pipe is 9 time more than in a distance of
18 m.
The energy of the radar signal spreads in case
of interfering surfaces which are further away
than a larger surface, so that reflected false
signals are weaker and hence more uncritical
than in the narrow range.