DE700 pages

Differential Pressure Transmitter

FISCHER
MESS- UND REGELTECHNIK

Type DE 70
General Description
The type DE 70 differential
pressure transmitter uses a
capacitance type sensor and
modern microprocessor
technology. It is ideally suited for
differential pressure applications
such as measurement of
● positive pressure,
● differential pressure,
● liquid level
where a high degree of accuracy
is required.
It is optionally available in
versions certified for use in
hazardous locations.

Features
● robust, wear resistant sensor
● high resistance to corrosion
● low hysteresis
● not affected by fouling of
pressure chambers
● capacitance type
silicon sensor
● microprocessor technology

145 D/2/0601 E

Principles of Operation
The type DE 70 differential
pressure transmitter uses
a silicon capacitance sensor
with a bridge measuring circuit,
the output of which changes
when the pressure changes.
Modern microprocessor technology is used to convert the
bridge output to a standard
4-20 mA signal, which permits
the measured value to be transmitted over long distances.
A hart interface is also available,
using an optional communication
module installed in the transmitter. With the hart interface,
digitally transmitted pressure
measurements, as well as the
transmitter’s set-up data can be
read very accurately by simply
connecting a compatible terminal
device at any point along the
length of the signal output loop.
Also, the terminal device can
also be used to re-configure the
transmitter’s set-up parameters:
locally, or from a remote location.

Subject to technical changes

The Measuring System

The DE 70 transmitter uses a precision silicon capacitance type pressure
sensing element, which is manufactured under stringently controlled
conditions. This sensor is rugged, resistant to effects of fatigue and
overloading, and unaffected by pressure fluctuations. The sensor and
microprocessor based signal proccessing ensure the highest possible
accuracy and stability.