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

Description
3.6 Functional principle
3.6.3.2

Measuring cell for differential pressure and flow rate

①
②
③
④
⑤
Figure 3-8
● Differential pressure is transmitted to the differential pressure sensor
diaphragms
● When measuring limits are exceeded, the seal diaphragm
diaphragm
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.
28
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
②
rests on the measuring cell body
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
.
④
. The differential pressure sensor
Operating Instructions, 06/2013, A5E00047092-09
-
⑤
through the seal
⑧
is displaced until the seal
SITRANS P DS III with HART
⑤
is