1.5
Unauthorised Modification
Modifications of or other technical alterations to the
instrument by the customer are not permitted. This
also applies to replacement parts. Any modifica-
tions / alterations required shall be carried out by
Fischer Mess- und Regeltechnik GmbH only.
1.6
Inadmissible Modes of Operation
The operational safety of this device can only be
guaranteed if it is used as intended. The device
model must be suitable for the medium used in the
system. The limit values given in the technical data
may not be exceeded.
1.7
Safe working practices for mainte-
nance and installation work
The safety instructions given in this operating man-
ual, any nationally applicable regulations on acci-
dent prevention and any of the operating company's
internal work, operating, and safety guidelines must
be observed.
The operating company is responsible for ensuring
that all required maintenance, inspection and instal-
lation work is carried out by qualified specialized
personnel.
1.8
Explanation of the symbols
WARNING!
… indicates a potentially dangerous
situation, non-observance of which
could endanger persons, animals, the
environment or objects.
INFORMATION!
… highlights important information for
efficient and fault-free operation.
TIP!
… highlights recommendations that
may be useful but which are not nec-
essarily required in specific situations.
2
Intended use
Display and switching device for differential pres-
sure of gaseous media. The instrument is to be ex-
clusively used for the applications agreed between
the manufacturer and user.
3
Description of the product and func-
tional description
3.1
Function diagram
3.2
Design and mode of operation
The device is based on two piezo-resistive sensor
elements that are suitable for measuring overpres-
sure, underpressure and differential pressure. The
pressures to be compared directly act on a silicon
diaphragm equipped with piezo-resistive resistors.
In case of equal pressure, the measuring dia-
phragm is in its idle state. In case of pressure dif-
ference, the force acting on the measuring mem-
branes causes it to be moved towards the side of
the lower pressure. This movement of the dia-
phragm induces a change of resistance, which is
evaluated by the device's electronics and trans-
formed into signals on the display, switch contacts
and an output signal.
The electronics analyses both sensor signals sepa-
rately. The signal from the first sensor influences
the switching output 1 and the optional output sig-
nal, the output signal from the second sensor, only
acts on the switching output 2.
4
Installation and assembly
The unit is designed for mounting on flat assembly
plates. For screw connection to the assembly plate,
the device features four assembly bores on its
back, which can be used for
3.5 mm tapping
screws.
Optionally, the device can be delivered with a wall-
mounting plate (see 13, order code).
At the factory, the device is calibrated for vertical
installation, but the installation position is arbitrary.
For installation positions deviating from the vertical,
the zero-point signal can be corrected by the inte-
grated zero-point adjuster (see 5.3.3).
The enclosure protection type IP 65 is only guaran-
teed, if a suitable power supply cable is used.
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