
The inlet pressure (p
e
)
is transferred to the gauge pressure sensor ⑥ via the seal diaphragm
④ and the filling liquid ⑤, displacing its measuring diaphragm. The displacement changes
the resistance of the four piezoresistors (bridge circuit) of the gauge pressure sensor. The
change in the resistance causes a bridge output voltage proportional to the inlet pressure.
Transmitters with measuring span ≤ 63 bar measure the inlet pressure against atmosphere,
those with measuring spans ≥ 160 bar against vacuum.
3.6.3.7 Measuring cell for absolute pressure, front-flush membrane
① Measuring cell ④ Filling liquid
② Process connection ⑤ Absolute pressure sensor
③ Seal diaphragm p
e
Inlet pressure
Figure 3-13 Function chart of the measuring cell for absolute pressure, flush mounted diaphragm
The
inlet pressure (p
e
) is transferred to the absolute pressure sensor ⑤ via the seal diaphragm
③ and the filling liquid ④, and displaces 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.
Description
3.6 Functional principle
SITRANS P, DS III series with HART
30 Operating Instructions, 09/2012, A5E00047092-08
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