Description
3.6 Principle of operation
SITRANS P DS III with PROFIBUS PA
32 Operating Instructions, 06/2013, A5E00053276-07
Measuring cell for absolute pressure from the differential pressure series
Seal diaphragm on the measuring cell
Measuring cell filling liquid
Figure 3-10 Function chart of measuring cell for absolute pressure
● Absolute pressure is transmitted to the absolute pressure sensor ⑤ through the seal
diaphragm
② and the filling liquid ⑦.
● When measuring limits are exceeded, the overload diaphragm
⑥ is displaced until the
seal diaphragm
② rests on the measuring cell body ④. The seal diaphragm thus
protects the absolute pressure sensor
⑤ from overload.
● The difference between the inlet pressure (p
e
) and the reference pressure ⑧ on the
negative side of the measuring cell displaces the seal diaphragm
②. 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 absolute
pressure.
To Next Page
Loading...
