VEGA VEGABAR 81 4 … 20 mA - Operating Instructions - Manual (Page 9)

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3 Product description
VEGABAR 81 • 4 … 20 mA
45025-EN-131010
Measured products are gases, vapours and liquids.
The chemical seal systems of VEGABAR 81, which are optimally
adapted to the process, also allow measurement of highly corrosive
and hot products.
The process pressure acts on the sensor element via the stainless
steel diaphragm and an internal transmission liquid. The process
pressure causes a resistance change which is converted into a cor-
responding output signal and outputted as measured value.
Measuring ranges up to 16 bar: piezoresistive sensor element, meas-
uring ranges up to 25 bar: strain gauge (DMS) sensor element.
1
3 4
2
Fig. 3: Configuration of the piezoresistive measuring cell
1 Sensor element
2 Base element
3 Diaphragm
4 Silicone oil filling
The measuring cell design depends on the selected pressure type.
Relative pressure: the measuring cell is open to atmosphere. The
ambient pressure is detected in the measuring cell and compensated.
It thus has no influence on the measured value.
Absolute pressure: the measuring cell is evacuated and encapsu-
lated. The ambient pressure is not compensated and does hence
influence the measured value.
Relative pressure, climate-compensated: the measuring cell is
evacuated and encapsulated. The ambient pressure is detected
through a reference sensor in the electronics and compensated. It
thus has no influence on the measured value.
The measuring system is completely welded and hence sealed
against the process. The sealing of the process fitting against the
process is carried out by a seal provided on site.
3.3 Packaging, transport and storage
Your instrument was protected by packaging during transport. Its
capacity to handle normal loads during transport is assured by a test
based on ISO 4180.
The packaging of standard instruments consists of environment-
friendly, recyclable cardboard. For special versions, PE foam or PE
Measured products
Measuring system
Pressure types
Seal concept
Packaging