FISCHER DE44 Operating Manual
d e v elopi n g s o l u t i o n s
*09005077*
BA_EN_DE44
Rev.B
11/18
*09005077*
Table of Content
1 Safety guidelines
2 Intended use
3 Description of the product and functional description
4 Installation and assembly
5 Commissioning
6 Maintenance
7 Transport
8 Service
9 Accessories
10 Disposal
11 Technical data
12 Dimensional drawings
13 Order Codes
14 Declaration of Conformity
1 Safety guidelines
1.1 General Information
This operating manual contains instructions fundamental to the installation,
operation and maintenance of the in-
strument that must be observed unconditionally. It must be read by the assembler, operator and the specialized personnel in charge of the
device before it is installed and put into operation.
This operating manual is part of the product and
therefore must be kept close to the device in a
place that is easily accessible for the responsible
personnel.
The following sections, in particular the instructions
about assembly, commissioning and maintenance,
contain important safety information, nonobservance of which could lead to risks to people,
animals, the environment and objects.
1.2 Personnel Qualification
The instrument may only be installed and commissioned by specialized personnel familiar with the installation, commissioning and operation of this
product.
Specialized personnel are persons who can assess
the work they have been assigned and recognize
potential dangers by virtue of their specialized training, their skills and experience and their knowledge
of the pertinent standards.
1.3 Risks due to Non-Observance of Safety Instructions
Non-observance of these safety instructions, the intended use of the device or the limit values given in
the technical specifications can be hazardous or
cause harm to persons, the environment or the
plant itself.
Claims for damages from the manufacturer are excluded in this case.
1.4 Safety Instructions for the Operating Company and the Operator
The safety instructions on correct operation of the
device shall be observed. The operating company
must make them available to the installation,
maintenance, inspection and operating personnel.
Dangers arising from electrical components, energy
discharged by the medium, escaping medium and
incorrect installation of the instrument must be eliminated. For more information, please refer to the
applicable national and international regulations.
In Germany these are the DIN EN, UVV and, in industry-specific cases, the DVGW-, Ex-, GL-, etc.,
the VDE guidelines and the regulations of the local
power utility companies.
Operating Manual
DE44
Digital two-channel
Differential pressure switch / Transmitter
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 modifications / 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 maintenance and installation work
The safety instructions given in this operating manual, any nationally applicable regulations on accident 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 installation 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 necessarily required in specific situations.
2 Intended use
Display and switching device for differential pressure of gaseous media. The instrument is to be exclusively 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 overpressure, 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 diaphragm is in its idle state. In case of pressure difference, the force acting on the measuring membranes causes it to be moved towards the side of
the lower pressure. This movement of the diaphragm induces a change of resistance, which is
evaluated by the device's electronics and transformed into signals on the display, switch contacts
and an output signal.
The electronics analyses both sensor signals separately. The signal from the first sensor influences
the switching output 1 and the optional output signal, 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 wallmounting 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 integrated zero-point adjuster (see 5.3.3).
The enclosure protection type IP 65 is only guaranteed, if a suitable power supply cable is used.
If the device is intended for outdoor use, we recommend permanently protecting the membrane
keypad against UV radiation and using a suitable
enclosure or at least the erection of a sufficiently
dimensioned canopy as a protection measure
against constant rain or snow.
4.1 Process connection
• By authorized and qualified specialized person-
nel only.
• The pipes need to be depressurized when the
instrument is being connected.
• Appropriate steps must be taken to protect the
device from pressure surges.
• Check the suitability of the device for the media
to be measured.
• Check that the pressure connections do not
leak before commissioning.
• Maximum pressures shall be observed.
• Do not blow into the pressure connections!
The pressure connections are marked with (+) and
(-) symbols on the device. For differential pressure
measurements, the higher pressure is connected to
the (+) side and the lower pressure to the (-) side of
the device.
The pressure measuring lines must be installed on
a gradient so that no air pockets e.g. for liquid
measurements, water pockets or for gas measurements can be created. If the required incline is not
reached, water and/or air filters need to be installed
at suitable points.
The pressure sensing lines need to be kept as short
as possible and installed without sharp bends to
avoid interfering delay times.
If the pressure sensing lines are already
pressurised at the time of commissioning, zero-point control and adjustment
cannot be performed. In such cases, the
device should be only connected to the mains without the pressure sensing lines.
4.2 Electronic connection
• By authorized and qualified specialized person-
nel only.
• The electrical connection of the device shall be
performed according to relevant VDE and local
electricity board regulations.
• Disconnect the system from the mains before
connecting the device.
• Add a fuse adapted to the energy requirements.
Connector 1: Power supply and output signal
Connector 2 : Switching outputs
The nominal supply voltage and the permissible
range can be found in the technical data.
The admissible load / resistance for the signal output is stated in the technical data.
The connection "Signal ground“(-Sig) is connected
internally to the supply ground. It only serves as the
ground connection for the output signal. This means
that the output signal is free of interference levels
on the power supply lines.
bridged internally
Signal
-Sig
Power supply
U
b
Signal +Sig
n.c.
Power supply
+U
b
SP1 SP2 SP2 SP1
5 Commissioning
All electrical supply, operating and measuring lines,
and the pressure connections must have been correctly installed before commissioning. All supply
lines are arranged so that there are no mechanical
forces acting on the device.
Check that the pressure connections do not leak
before commissioning.
5.1 Display
• The 3.5 digit LCD display represents the cur-
rent differential pressure in normal mode.
• The selected measuring unit is illuminated on
the right of the display.
The units shown in the picture may vary from
the actual model.
• Two light diodes and above the display in-
dicate the status of the switching outputs. As
soon as the switch is closed, the respective
LED shines.
• On the left side, P1 and/or P2 show which
channel is currently being displayed.
When the parameters are being set, the display either shows the respective menu item or the associated parameter value. The device continues to
function whilst the parameters are being set; apart
from two exceptions, the changes come into effect
instantly.
The exceptions are firstly a change of switching
times – here, the previously valid time needs to
have ended and a change to the support point table
(see 5.3.8 or 5.3.9). Here all output signals and
switching states are frozen until the changes have
been completed.
5.2 Operating keys
The operating keys have the following function:
ÿ
Page down menu
Reduce value
û
Enter key
þ
Page up menu
Increase value
5.3 Configuration
For commissioning there is a multitude of setting
options for optimum adaptation of the device to the
measuring point and task at hand. This section covers these options step by step.
Depending on the device model 1 some menu items
may not be available. For example, all characteristic
curve functions are faded out in the menu if the device does not have a signal output.
It is possible to completely configure the
device using a PC adapter at the PC.
Here all parameters are directly visible
and accessible. Also, the entire configuration can be loaded, saved and documented as a
printout. For more information about this program,
please refer to the program documentation (cf. Accessories).
5.3.1 General points
Connect the device to the power supply and ensure
that it is not under any pressure (if necessary, disconnect any pressure lines).
Proceed as follows to set a parameter:
• Press the enter key û to switch to the menu.
ESc will appear on the display.
• Use the arrow keys ÿ þ to select a parameter
from the list.
• Press the enter key û to call up the parameter.
• Use the arrow keys ÿ þ to set the required val-
ue.
• Press the enter key û to save the value.
After setting all parameters, leave the menu as fol-
lows:2
• Use the arrow keys ÿ þ to set the ESc parame-
ter. You will find these at the start and also at
the end of the list of parameters.
• Press the enter key û to leave the menu.
5.3.2 Selecting the pressure unit
First select the pressure measuring unit. The unit
that is currently valid is illuminated to the right of the
number displays. Press the middle key û to make
the setting and then search for the parameter EIN
using the right-hand key þ. Press û again an then
change the displayed value using þ or ÿ.
1 = top
2 = middle
3 = bottom
1
with regard to the transmitter signal, voltage output, current
output, etc.
2
All set parameter values are only valid once you leave the
menu via the ESC parameter.
Switching output 1
Switching output 2
3.5 character LED display
Operating keys
Measuring unit
Channel no.
Once the value has been selected, save it with û
and EIN will appear again in the display.
Then leave the setting mode. Press ÿ until Esc and
the û appear. The current measured pressure is
shown again. The correct pressure unit is now illuminated to the right of this.
The display can only show up to ±1999.
Therefore in some cases it may not be
possible to select all stated pressure
units.
5.3.3 Display settings
Due to the fact that the DE44 has two independent
pressure measuring systems but only one display,
you can use the dSP parameter to select whether
you want to have only the first channel (dSP = 0.0),
only the second channel (dSP = 0.1) or both channels alternately (dSP = 0.2 to 99.9) displayed. From
0.2 s upwards, the value simply determines the retention period (0.2 s to 99.9 s per channel). So that
it is clear which value is currently being displayed,
the symbols P1 for the 1st channel and P2 for the
2nd channel are shown accordingly on the left edge
of the display.
It is advisable for the other settings to initially select a slow switching time (e.g. 3
s). This saves you the effort of having to
switch between P1 and P2 manually.
5.3.4 Zero point control and adjustment
Ensure that the device is not under any pressure (if
necessary, disconnect any pressure lines).
If the device does precisely indicate zero at this
point of time, parameter OF1 enables you to adjust
the measuring value exactly to zero. To do so, you
have to set the measuring value indicated below OF1
to zero.
Due to the fact that the DE44 has two independent
pressure measuring systems, there is also an offset
correction parameter OF2 for the second measuring
channel. The function and effect is identical to OF1.
After zero-point adjustment, the pressure sensing
lines can be reconnected.
5.3.5 Damping and zero-point stabilising
If there are unsteady pressure readings at this point
of time or during operation, you can use parameters
DAM and NP to stabilise the reading (and the output
signal).
The parameter DAM functions like a capillary throttle.
However, it only acts on the display, output signal
and switch points but not on the measuring cell itself. This parameter can be used to set the reaction
time to the pressure jumps. The value range is 0.0 s
to 100.0 s.
But with maximum attenuation, it will
take more than 2 minutes for the reading to also reach zero after a pressure
jump from nominal pressure (100 %) to
zero!
In many cases, unsteady readings are not a problem during normal operating mode, but this is not
true for the idle state, i.e. if zero (differential) pressure is expected.
In such situations, parameter NP can be applied. Its
value defines a measuring value range around zero. Within this range, the measuring value is set to
zero.
Example:
A value of 0.08 mbar 3 is entered for NP. In this
case all pressures within the range of -0.08
mbar to +0.08 mbar are set to zero. The reading will only not indicate zero anymore if the
pressure exceeds these limits. However, the
pressure value and display do not correspond
to one hundred percent. The measuring pressure and reading match again when the double
value, in this case 0.16 mbar, is reached again.
5.3.6 Setting the output signal
The transmitter output signal primarily depends on
the sensed pressure. However, you have the option
of adjusting the output signal to a large extent to
suit your requirements.
However, the basic measuring range
(indicated on the type label) and the
type of output signal (voltage / current)
are not variable.
Parameters MA (start of measuring range) and ME
(end of measuring range) define the two pressures
between which the output signal can generally
change. Both values are adjustable across the entire basic measuring range. The set values always
refer to pressure (in the relevant measuring unit)
and are converted when the measuring unit is
changed.
The assigned signal values for MA and ME are invariable (type label, e.g. 0…10 V or 4…20 mA).
If the parameter MA and/or ME is
changed, a support point table that is
active at this time will be deleted (cf.
5.3.8 or 5.3.9).
If MA is smaller than ME this is referred ´to a rising
characteristic curve. The output signal grows as the
pressure increases.
If ME is smaller than MA, this is a decreasing characteristic curve and the output signal decreases
with the falling pressure.
3
0.08 mbar ≙ 8 Pa
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