VEGA VEGABAR 82 Save sensor - Operating Instructions - Manual (Page 9)

9
3 Product description
VEGABAR 82 • Slave sensor for electronic differential pressure
45050-EN-131011
•
Absolute pressure
•
Vacuum
Measured products are gases, vapours and liquids.
Depending on the process fitting and measurement setup, measured
products can be also viscous or contain abrasive substances.
Sensor element is the CERTEC ® measuring cell with robust ceramic
diaphragm. The process pressure deflects the ceramic diaphragm
and causes a capacitance change in the measuring cell. This capaci-
tance change is converted into an electrical signal and outputted as
measured value via the output signal.
The CERTEC
® measuring cell is available in two sizes:
•
ø 17.5 mm with small process fittings
•
ø 28 mm with large process fittings as well as all flange connec-
tions
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 following presentations show the installation of the CERTEC ®
measuring cell into the process fitting and the different seal concepts.
1
2
4
5
3
Fig. 3: Recessed installation of the CERTEC ® measuring cell
1 Measuring cell
2 Seal for the measuring cell
3 Diaphragm
4 Process fitting
5 Seal for the process fitting
Measured products
Measuring system
Pressure types
Seal concepts
Recessed installation