
● Flange connection in accordance with EN 61518
●
Flush-mounted process connections
3.6.3.1 Measuring cell for gauge pressure
① Reference pressure opening ⑤ Filling liquid
② Measuring cell ⑥ Gauge pressure sensor
③ Process connection p
e
Inlet pressure
④ Seal diaphragm
Figure 3-7 Function chart of measuring cell for gauge pressure
The
inlet pressure (p
e
) is transferred to the gauge pressure sensor ⑥ via the seal diaphragm
④ and the fill fluid ⑤, displacing its measuring diaphragm. The displacement changes the
resistance of the four piezoresistors (bridge circuit) of the gauge pressure sensor. The change
in the resistance causes a bridge output voltage proportional to the inlet pressure.
Transmitters with measuring span ≤ 63 bar measure the inlet pressure against atmosphere,
those with measuring spans ≥ 160 bar against vacuum.
Description
3.6 Functional principle
SITRANS P, DS III series with HART
Operating Instructions, 09/2012, A5E00047092-08 25
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