Siemens SITRANS P DS III - Remote Seal

Description
3.7 Remote seal
SITRANS P DS III with PROFIBUS PA
Operating Instructions, 06/2013, A5E00053276-07
35
The inlet pressure (p
e
) is transferred to the absolute pressure sensor ⑤ via the seal
diaphragm
③ and the filling liquid ④, and displaces its measuring diaphragm. 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 inlet pressure.
3.7
Remote seal
Product description
● A remote seal measuring system comprises the following elements:
– Remote seal
– Transmission line, e.g. capillary line
– Transmitter.
Note
Malfunction of the remote seal measuring system
If you separate the components of the remote seal measuring system, this results in
malfunctioning of the system.
Do not separate the components under any circumstances.
● The measuring system based on a hydraulic principle is used to transfer pressure.
● The capillary line and the remote seal diaphragm are the most sensitive components in
the remote seal measuring system. The material thickness of the remote seal diaphragm
is only ∼ 0.1 mm.
● The smallest of leakages in the transmission system leads to the loss of transmission
fluid.
● The loss of transmission fluid results in inaccuracies in the measurement and failure of
the measuring system.
● In order to avoid leaks and measuring errors, please observe the installation and
maintenance instructions in addition to the safety notes.