VEGA VEGAFLEX 61 4 … 20 mA_HART four-wire User Manual
Page 12
keep in mind that measurement down to the tip of the probe is not
possible. The exact value of the min. distance (lower dead band) is
stated in chapter "Technical data".
Fig. 3: Vessel with conical bottom
P
lastic vessel/Glass vessel
T
he guided microwave principle requires a metal surface on the
process fitting. Therefore use in plastic vessels etc. an instrument
version with flange (from DN 50) or place a metal sheet (ø > 200 mm/
8
in) beneath the process fitting when screwing it in.
M
ake sure that the plate has direct contact with the process fitting.
I
n bypass tubes of plastic, a metal screen must be provided on the
outside. You can glue metal foil, for example, on the outside along the
entire length of the tube. This metal screen must be connected to the
ground terminal on the instrument.
W
hen installing rod or cable probes without metal vessel wall, e.g. in
plastic vessels, the measured value can be influenced by strong
electromagnetic fields (emitted interference according to EN 61326:
class A).
I
n this case, use a probe in coax version.
Vessel type
12
VEGAFLEX
61 • 4 … 20
mA/HART four-wire
4 M
ounting
31834
-EN
-100426