Measuring Cell For Absolute Pressure From The Differential Pressure Series - Siemens SITRANS P DS III Operating Instructions Manual

3.7.3.4

Measuring cell for absolute pressure from the differential pressure series

①
②
③
④
⑤
Image 3-8
● Absolute pressure is transmitted to the absolute pressure sensor
diaphragm
● When measuring limits are exceeded, the overload diaphragm
seal diaphragm
protects the absolute pressure sensor
● The difference between the inlet pressure (p
negative side of the measuring cell displaces the seal diaphragm
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 absolute
pressure.
SITRANS P DS III/P410 with PROFIBUS PA
Operating Instructions, 02/2016, A5E00053276-08
Pressure cap
Seal diaphragm on the measuring cell
O-ring
Measuring cell body
Absolute pressure sensor
Function chart of measuring cell for absolute pressure
②
and the filling liquid
②
rests on the measuring cell body
⑥
Overload diaphragm
⑦
Measuring cell filling liquid
⑧
Reference pressure
p Pressure input variable
e
⑦
.
④
. The seal diaphragm thus
⑤
from overload.
) and the reference pressure
e
Description
3.7 Principle of operation
⑤
through the seal
⑥
is displaced until the
⑧
on the
②
. The displacement
33