
● The change in the resistance causes a bridge output voltage proportional to the absolute
pressure.
3.6.3.5
Measuring cell for absolute pressure from the gauge pressure series
① Measuring cell ④ Filling liquid
② Process connection ⑤ Absolute pressure sensor
③ Seal diaphragm ⑥ Inlet pressure
Figure 3-11 Function chart of measuring cell for absolute pressure
The inlet pressure (p
e
) is transferred to the absolute pressure sensor ⑤ via the seal diaphragm
③ and the fill fluid ④, displacing its measuring diaphragm. The displacement changes the
resistance of the four piezoresistors (bridge circuit) of the absolute pressure sensor. The
change in the resistance causes a bridge output voltage proportional to the inlet pressure.
3.6.3.6 Measuring cell for gauge pressure, front-flush membrane
① Reference pressure opening ⑤ Filling liquid
② Measuring cell ⑥ Gauge pressure sensor
③ Process connection p
e
Inlet pressure
④ Seal diaphragm
Figure 3-12 Function chart of the measuring cell for gauge pressure, flush mounted diaphragm
Description
3.6 Functional principle
SITRANS P, DS III series with HART
Operating Instructions, 09/2012, A5E00047092-08 29
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