Siemens SITRANS Series - Measuring Cell for Absolute Pressure, Front-Flush Membrane

● 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.
4.4.3.4 Measuring cell for absolute pressure, front-flush membrane
S
H





① Measuring cell ④ Filling liquid
② Process connection ⑤ Absolute pressure sensor
③ Seal diaphragm p
e
Inlet pressure
Figure 4-10 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
4.4 Functional principle
SITRANS P320/P420 (mA/HART)
Operating Instructions, 06/2018, A5E44852162-AA 33