Measuring Cell For Gauge Pressure, Front-Flush Membrane; Measuring Cell For Absolute Pressure From The Gauge Pressure Series - Siemens SITRANS P Operating Instructions Manual

Description
4.4 Functional principle
4.4.2.2

Measuring cell for gauge pressure, front-flush membrane

①
②
③
④
Figure 4-8
The inlet pressure (p
④
and the filling liquid
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.
Pressure transmitters with measuring span ≤ 63 bar measure the inlet pressure against
atmosphere, those with measuring spans ≥ 160 bar the inlet pressure against vacuum.
4.4.2.3

Measuring cell for absolute pressure from the gauge pressure series

①
②
③
Figure 4-9
34
Reference pressure opening
Measuring cell
Process connection
Seal diaphragm
Function chart of the measuring cell for gauge pressure, flush mounted diaphragm
) is transferred to the gauge pressure sensor
e
⑤
, displacing its measuring diaphragm. The displacement changes the
Measuring cell
Process connection
Seal diaphragm
Function chart of measuring cell for absolute pressure
⑤
Filling liquid
⑥
Gauge pressure sensor
p Inlet pressure
e
⑥
via the seal diaphragm
④
Filling liquid
⑤
Absolute pressure sensor
P Inlet pressure
e
SITRANS P320/P420 with 4 to 20 mA/HART
Operating Instructions, 11/2019, A5E44852162-AC