VEGA VEGAFLEX 67 (-40…+150°C) 4 … 20 mA_HART four-wire - Manual (Page 8)

l A rticle numbers, documentation
W ith the serial number, you can access the delivery data of the
instrument via www.vega.com, "VEGA Tools" and "serial number
search". In addition to the type label outside, you can also find the
serial number on the inside of the instrument.
3 .2 Principle of operation
VEGAFLEX 67 is a level sensor with coax, rod or cable probe for
continuous interface measurment.
I t is designed for industrial use in all areas of process technology and
can be used in liquids.
H igh frequency microwave impulses are guided along a steel cable or
rod or a rod inside a steel tube. When reaching the product surface, a
part of the microwave impulses is reflected. The other part passes the
upper product and is reflected a second time by the interface. The
running times to the two product layers are processed by the
instrument.
Upper medium (L2)
l T he upper medium must not be conductive
l T he dielectric figure of the upper medium must be known (input
required). Min. dielectric figure: rod version 1.7; coax version 1.4.
Y
ou can find a list with the dielectric figures on our home page:
www.vega.com
l T he composition of the upper medium must be stable, no varying
products or mixtures
l T he upper medium must be homogeneous, no stratifications within
the medium
l M in. thickness of the upper medium 100 mm
l C lear separation from the lower medium, no emulsion phase, no
mull layer
l I
f possible, no foam on the surface
Lower medium (L1)
l T
he dielectric figure must be 10 higher than the dielectric figure of
the upper medium, preferably electrically conductive. Example:
upper medium dielectric figure 2, lower medium at least dielectric
fi
gure 12
Application range
Functional principle
Prerequisites for inter-
face measurement
8 VEGAFLEX 67 • 4 … 20 mA/HART - four-wire
3 P roduct description
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