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3 Product description
VEGABAR 82 • Profibus PA
45031-EN-220624
16 µm
1
2
3
Fig. 4: Configuration of the CERTEC
®
measuring cell
1 Process diaphragm
2 Glass joint
3 Base element
The measuring cell is available in two sizes: CERTEC
®
(ø 28 mm) and
Mini-CERTEC
®
(ø 17.5 mm).
Temperature sensors in the ceramic diaphragm and on the ceramic
body of the CERTEC
®
measuring cell or on the electronics of the
Mini-CERTEC
®
measuring cell detect the current process tempera-
ture. The temperature value is output via:
•
The display and adjustment module
•
The current output or the additional current output
•
The digital signal output
Even extreme jumps in process temperature are immediately de-
tected by the CERTEC
®
measuring cell. The values in the ceramic
diaphragm are compared with those on the ceramic base body. Within
a few measuring cycles, the intelligent sensor electronics compen-
sates for otherwise unavoidable measurement deviations caused by
temperature shocks in the range. Depending on the adjusted damp-
ing, these cause only slight and brief changes in the output signal.
The measuring cell design depends on the selected pressure type.
Relative pressure
: the measuring cell is open to the atmosphere.
The ambient pressure is detected in the measuring cell and compen-
sated. It thus has no influence on the measured value.
Absolute pressure
: the measuring cell contains vacuum and is
encapsulated. 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 examples for the installation of the
ceramic measuring cell into the process fitting and the different seal
concepts.
Measuring system tem-
perature
Pressure types
Seal concepts