FISCHER DE49 A Series, Operating Manual

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FISCHER Mess- und Regeltechnik GmbH Product and functional description | 2
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2.5 Design and mode of operation
The multifunctional differential pressure transmitter with 2-conductor technology
allows the measurement of under-pressure, over-pressure and differential pres-
sure in liquid and gaseous media. The basis is a piezoresistive pressure sensor
that is attached to a base with glass openings on the inside of a metal case.
The pressures that are to be compared are fed to the inner and outer side of the
sensor membrane via a pressure transfer liquid. The separating membranes
transfer the medium pressure to the pressure transfer liquid.
Piezo resistors are diffused into the silicone membrane. The force resulting from
the differential pressure changes acts on the membrane and changes the resist-
ance. This is measured and processed by the analysis electronics. The meas-
ured value is shown on the LC display and illustrated as an analogue 4-20 mA
signal in the supply circuit.