Measuring Cell For Differential Pressure And Flow Rate - Siemens SITRANS P DS III Operating Instructions Manual

3.7.3.2

Measuring cell for differential pressure and flow rate

①
②
③
④
⑤
Image 3-6
● Differential pressure is transmitted to the differential pressure sensor
diaphragms
● When measuring limits are exceeded, the seal diaphragm
diaphragm rests on the measuring cell body
thus protected against overloading since no further deflection of the overload diaphragm
⑥
● The seal diaphragm
changes the resistance of the four piezoresistors (bridge circuit) of the differential
pressure sensor.
● The change in the resistance causes a bridge output voltage proportional to the
differential pressure.
SITRANS P DS III/P410 with PROFIBUS PA
Operating Instructions, 02/2016, A5E00053276-08
Inlet pressure P
+
Pressure cap
O-ring
Measuring cell body
Differential pressure sensor
Function chart of the measuring cell for differential pressure and flow rate
⑧
and the filling liquid
is possible.
⑧
is displaced by the differential pressure. The displacement
⑥
Overload diaphragm
⑦
Filling liquid
⑧
Seal diaphragm
⑨
Inlet pressure P
⑦
.
⑧
④
. The differential pressure sensor
Description
3.7 Principle of operation
-
⑤
through the seal
is displaced until the seal
⑤
is
31