FISCHER DS31 User manual

Operating manual
DS31
Differential pressure switch
09005344 • BA_EN_DS31 • Rev. ST4-C • 07/21 *09005344*

| Masthead FISCHER Mess- und Regeltechnik GmbH
2/20 BA_EN_DS31
Masthead
Manufacturer: FISCHER Mess- und Regeltechnik GmbH
Bielefelderstr. 37a
D-32107 Bad Salzuflen
Telephone: [phone]
Telefax: [phone]
eMail: [email protected]
web: www.fischermesstechnik.de
Technical editorial team: Documentation representative: T. Malischewski
Technical editor: R. Kleemann
All rights, also those to the translation, reserved. No part of this document may
be reproduced or processed, duplicated or distributed using electronic systems
or any other form (print, photocopy, microfilm or another process) without the
written consent of the company FISCHER Mess- und Regeltechnik GmbH, Bad
Salzuflen.
Reproduction for internal use is expressly allowed.
Brand names and procedures are used for information purposes only and do
not take the respective patent situation into account. Great care was taken
when compiling the texts and illustrations; Nevertheless, errors cannot be ruled
out. The company FISCHER Mess- und Regeltechnik GmbH will not accept any
legal responsibility or liability for this.
Subject to technical amendments.
© FISCHER Mess- und Regeltechnik 2020
Version history
Rev. ST4-A 08/20 Version 1 (first edition)
Rev. ST4-B 06/21 Version 2 (CE declaration updated)
Rev. ST4-C 07/21 Version 3 (order code/electrical connection corrected)

FISCHER Mess- und Regeltechnik GmbH Table of contents
BA_EN_DS31 3/20
Table of contents
1 Safety instructions .......................................................................................................... 4
1.1 General................................................................................................................................... 4
1.2 Personnel Qualification........................................................................................................... 4
1.3 Risks due to Non-Observance of Safety Instructions............................................................. 4
1.4 Safety Instructions for the Operating Company and the Operator ......................................... 4
1.5 Unauthorised Modification...................................................................................................... 4
1.6 Inadmissible Modes of Operation........................................................................................... 4
1.7 Safe working practices for maintenance and installation work............................................... 5
1.8 Pictogram explanation............................................................................................................ 5
2 Product and functional description ............................................................................... 6
2.1 Delivery scope........................................................................................................................ 6
2.2 Design and mode of operation ............................................................................................... 6
2.3 Intended use........................................................................................................................... 6
2.4 Function diagram.................................................................................................................... 6
2.5 Product summary ................................................................................................................... 7
3 Assembly.......................................................................................................................... 8
3.1 General................................................................................................................................... 8
3.2 Process connection ................................................................................................................ 8
3.3 Electrical connections............................................................................................................. 9
4 Start-up ............................................................................................................................. 11
4.1 General................................................................................................................................... 11
4.2 Switching point setting............................................................................................................ 11
5 Servicing........................................................................................................................... 12
5.1 Maintenance ........................................................................................................................... 12
5.2 Transport ................................................................................................................................ 12
5.3 Service.................................................................................................................................... 12
5.4 Disposal.................................................................................................................................. 12
6 Technical data.................................................................................................................. 13
6.1 General................................................................................................................................... 13
6.2 Input variables ........................................................................................................................ 13
6.3 Output parameters.................................................................................................................. 13
6.4 Measuring accuracy ............................................................................................................... 13
6.5 Electrical connection............................................................................................................... 13
6.6 Operating conditions............................................................................................................... 14
6.7 Construction design................................................................................................................ 14
7 Order codes...................................................................................................................... 16
8 Attachment ....................................................................................................................... 17

1 | Safety instructions FISCHER Mess- und Regeltechnik GmbH
4/20 BA_EN_DS31
1 Safety instructions
1.1 General
This operating manual contains basic instructions for the installation, operation
and maintenance of the device that must be followed without fail. It must be
read by the installer, the operator and the responsible specialist personnel be-
fore installing and commissioning the device.
This operating manual is an integral part of the product and therefore needs to
be kept close to the instrument in a place that is accessible at all times to the re-
sponsible personnel.
The following sections, in particular instructions about the assembly, commis-
sioning and maintenance, contain important information, non-observance of
which could pose a threat to humans, animals, the environment and property.
The instrument described in these operating instructions is designed and manu-
factured in line with the state of the art and good engineering practice.
1.2 Personnel Qualification
The instrument may only be installed and commissioned by specialized person-
nel 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.
The supplier of the equipment will not be liable for damage claims if this should
happen.
1.4 Safety Instructions for the Operating Company and the
Operator
The safety instructions governing correct operation of theinstrument must 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 device must be eliminated.
See the information in the applicable national and international regulations.
Please observe the information about certification and approvals in the Tech-
nical Data section.
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. Only the manufacturer
is authorised to make any modifications or changes.
1.6 Inadmissible Modes of Operation
The operational safety of this instrument can only be guaranteed if it is used as
intended. The instrument model must be suitable for the medium used in the
system. The limit values given in the technical data may not be exceeded.
The manufacturer is not liable for damage resulting from improper or incorrect
use.

FISCHER Mess- und Regeltechnik GmbH Safety instructions | 1
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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 mainten-
ance, inspection and installation work is carried out by qualified specialized per-
sonnel.
1.8 Pictogram explanation
DANGER
Type and source of danger
This indicates a direct dangerous situation that could lead to death or serious
injury (highest danger level).
1. Avoid danger by observing the valid safety regulations.
WARNING
Type and source of danger
This indicates a potentially dangerous situation that could lead to death or ser-
ious injury (medium danger level).
1. Avoid danger by observing the valid safety regulations.
CAUTION
Type and source of danger
This indicates a potentially dangerous situation that could lead to slight or seri-
ous injury, damage or environmental pollution (low danger level).
1. Avoid danger by observing the valid safety regulations.
NOTICE
Note / advice
This indicates useful information of advice for efficient and smooth operation.

2 | Product and functional description FISCHER Mess- und Regeltechnik GmbH
6/20 BA_EN_DS31
2 Product and functional description
2.1 Delivery scope
• DS31 Differential pressure switch
• Operating Manual
2.2 Design and mode of operation
Due to the pressure or differential pressure to be measured, a one-sided force
acts on the membrane. This force moves the membrane system against the
pre-tensioned measuring range spring. A switch tappet mounted on the mem-
brane actuates a micro switch.
The switch-point can be set with the setting button of the adjustment spindle.
One scale and a setting mark attached to the type plate show the respectively
set switch-point.
2.3 Intended use
The DS31 is a differential pressure switch for overpressure, underpressure and
differential pressure measurements. The uncomplicated and durable membrane
measuring mechanism is suitable for neutral fluid media, e.g. service water,
heating water, neutral gases and oils.
2.4 Function diagram
12 3 4 5
6
+
Fig.1: Function diagram
1 Micro-switch 2 Switch tappet
3 Diaphragm 4 Measuring range spring
5 Adjustment spindle with setting
button
6 Pressure chamber

FISCHER Mess- und Regeltechnik GmbH Product and functional description | 2
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2.5 Product summary
1
2
3 4 5
6
7
8
9
Fig.2: Product summary
1 Connection cable 2 Cable screw connection
3 Cover hood 4 Pressure chamber
5 Mounting foot 6 Scale
7 Setting button 8 Cutting ring screw connection
9 Type plate
2.5.1 Process connection
As standard, the device has a process connection G⅛ inch inner thread. How-
ever, the device can also be supplied with cutting ring screw connections for 6
or 8 mm tubes.
The maximum torque for the G⅛ inch inner thread is 5 Nm. The cutting ring
screw connections may only be mounted with counter brackets (cf. operating in-
structions/assembly).
2.5.2 Type plate
This type plate serves as an example of the information that is stated. The data
shown is purely fictive, but does correspond to the actual conditions. For more
information, please see the order code at the end of these instructions.
Type
Setting range
Prod.-No.
Switching rate 3A / 250V AC
Differential Pressure Switch
DS3101FM00A0
0 ... 0.6 bar
2006640.02.012
Order code
Serial number
Setting marking
Marking
Process connection
Fig.3: Type plate

3 | Assembly FISCHER Mess- und Regeltechnik GmbH
8/20 BA_EN_DS31
3 Assembly
3.1 General
The device is intended for installation on flat walls and mounting plates. The
device has a mounting foot for screwing to the mounting plate.
3.2 Process connection
• By authorized and qualified specialized personnel only.
• The pipes need to be depressurized when the instrument is being connec-
ted.
• Appropriate steps must be taken to protect the device from pressure surges.
• Check that the device is suitable for the medium being measured.
• Maximum pressures must be observed (cf. Tech. data)
The pressure lines must be installed at an inclination so that when fluids are
measured no air pockets are created or when measuring gases, no water pock-
ets are created. If the required inclination is not reached, water or air filters must
be installed at suitable places.
If water is used as a measuring medium, the unit must be protected against
frost.
The pressure lines must be kept as short as possible and installed without any
tight bends to avoid delays.
Pulsating pressure on the system side can lead to wear and functional prob-
lems. To safeguard this, we recommend installing absorption elements in the
pressure line.
The process connections are marked with (+) and (-) symbols on the device.
The pressure lines must be mounted according to these symbols.
1. Differential pressure measurement
Higher pressure
lower pressure
2. Pressure measurement
Pressure
open
3.2.1 Cutting ring screw connection
Counter-bracket
Cutting ring (pre-mounted)
Union nut
Precision tube
14 mm
14/17 mm
Fig.4: Process connection

FISCHER Mess- und Regeltechnik GmbH Assembly | 3
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CAUTION
Maximum tightening torque
The maximum torque for the G⅛ inch inner thread is 5 Nm. The cutting ring
screw connections may only be mounted with counter brackets.
Preparation
• Assembly is only possible with tubes that are cut off at right angles. The
usual tolerances for minimum tube length, angle and chamber apply.
• Pre-mount the cutting ring.
• Use a lubricant with stainless steel.
Assembly at the assembly site
• Place the pre-mounted tube end with the cutting ring and union nut into the
tube screw connection.
• Apply counter-pressure on the tube screw connection with a wrench.
• Use a wrench to tighten the union nut approx. 1/4 to 1/3 turns until a notice-
ableincrease inforceisfelt.
3.3 Electrical connections
• By authorized and qualified specialized personnel only.
• When connecting the unit, the national and international electro-technical
regulations must be observed.
• Disconnect the system from the mains, before electrically connecting the
device.
• Install the consumer-adapted fuses.
• Do not connect the connector if strained.
Cable screw connection without cables
1
2
Options micro-switch
1 2 1 2
Lid screw
3 mm
1.2 x 7 mm
0.4 x 1.2 mm
COM
NO
NC
Fig.5: Electrical connections

3 | Assembly FISCHER Mess- und Regeltechnik GmbH
10/20 BA_EN_DS31
With permanently wired numbered cables
Optionally, a numbered cable (see order code) is permanently wired. The cable
numbers correspond to the numbers of the terminals.

FISCHER Mess- und Regeltechnik GmbH Start-up | 4
BA_EN_DS31 11/20
4 Start-up
4.1 General
A prerequisite for commissioning is correct installation of all electrical supply
lines and the differential pressure lines. All connections are arranged so that
there are no mechanical forces acting on the device.
CAUTION
Leak test
The differential pressure lines need to be checked for leaks before commission-
ing.
In the case of fluid measuring media, the differential pressure lines must be
vented because different fluid columns in the lines will distort the measure-
ments.
If water is used as a measuring medium, the unit must be protected against
frost.
4.2 Switching point setting
The required switch point is set by turning the setting knob. The switch point
marking on the type plate shows the set value on the scale of the setting knob.
Scale
Setting button
Type
Setting range
Prod.-No.
Switching rate 3A / 250V AC
Differential Pressure Switch
DS3103FM00A0
0 ... 1.6 bar
2006640.02.012
Switch-point marking
Fig.6: Switching point setting

5 | Servicing FISCHER Mess- und Regeltechnik GmbH
12/20 BA_EN_DS31
5 Servicing
5.1 Maintenance
The instrument is maintenance-free. We recommend the following regular in-
spection to guarantee reliable operation and a long service life:
• Check the function in combination with downstream components.
• Check the leak-tightness of the pressure connection lines.
• Check the electrical connections.
The exact test cycles need to be adapted to the operating and environmental
conditions. In combination with other devices, the operating instructions for the
other devices also need to be observed.
5.2 Transport
The measuring device must be protected against impacts. It should be transpor-
ted in the original packaging or a suitable transport container.
5.3 Service
All defective or faulty devices should be sent directly to our repair department.
Please coordinate all shipments with our sales department.
WARNING
Process media residues
Process media residues in and ondismantled devices can be a hazard to
people, animals and the environment. Take adequate preventive measures. If
required, the devices must be cleaned thoroughly.
Return the device in the original packaging or a suitable transport container.
5.4 Disposal
Please help to protect the environment by always disposing of the work pieces
and packaging materials in compliance with the valid national waste and recyc-
ling guidelines or reuse them.

FISCHER Mess- und Regeltechnik GmbH Technical data | 6
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6 Technical data
6.1 General
Reference conditions (acc. to IEC 61298-1)
Temperature +15 to +25 °C
Relative humidity 45 … 75 %
Air pressure 86 to 106 kPa 860 to 1060 mbar
Installation position User-defined
6.2 Input variables
Measuring
range
Adjustment
range
Nominal
pressure
Bursting
pressure
10 … 100% SI unit
0 to 400 mbar 4 to 400 mbar 0.4 to 40 kPa PN16 64 bar
0 to 0.6 bar 0.06 to 0.6 bar 6 to 60 kPa
0 to 1 bar 0.10 to 1.0 bar 10 to 100 kPa
0 to 1.6 bar 0.16 to 1.6 bar 16 to 160 kPa
0 to 2.5 bar 0.25 to 2.5 bar 25 to 250 kPa
0 to 4 bar 0.40 to 4.0 bar 40 to 400 kPa
0 to 6 bar 0.60 to 6.0 bar 60 to 600 kPa
6.3 Output parameters
Micro-switch AC DC
Max. switching voltage 250 V 30 V
Max. switching current 3 A 0.4 A
Min. switching current 0.1A 0.1A
Max. switching output 250 VA 10 W
Mech. life span 106 switching cycles
6.4 Measuring accuracy
Switch point adjustment range 10 … 100 % of the adjustment range
Switch point accuracy 3% of the adjustment range
Hysteresis 5% of the adjustment range
6.5 Electrical connection
Hard-wired, silicone and halogen-free number cable
Core number 2 + PE
Conductor nominal cross-section 0.75 mm2
AWG 19
Outer diameter 7.1 mm
Cable screw connection without cables
Internal connection terminal 2
Earthing Connection screw for M4 ring cable lug
Conductor nominal cross-section 1 … 2.5 mm2
Cable screw connection M16x1.5
Terminal range 5.0 … 10 mm

6 | Technical data FISCHER Mess- und Regeltechnik GmbH
14/20 BA_EN_DS31
6.6 Operating conditions
Ambient temperature range -10 to +70 °C
Storage temperature range -10 to +80 °C
Medium temperature range
(for non-freezing media)
-10 to +80 °C
Low-Voltage Directive EN 61010-1:2010 +A1:2019+A1:2019/
AC2019
RoHS EN IEC 63000:2018
Protection class IP 65 acc. to EN 60529
Materials of the parts that come into contact with the surroundings
Lid, setting button POM
Pressure chamber CW614N
Cable screw connection Polyamide
Connection cable PVC halogen-free, flame-retardant
Mounting foot Galvanised steel and passivated
Materials of the parts that come into contact with the measuring medium
Pressure chamber CW614N
O-rings and membrane Stainless steel 1.431 NBR or FKM
(acc. to order key)
Adjustment spindle, membrane plate CW614N
Switch fields 1.4310
Other parts CW614N, PTFE
6.7 Construction design
All dimensions in mm unless otherwise stated
5.5
26
125
47.5
50 43
Cable screw connection
M16 x 1.5
Fig.7: Dimension drawing

FISCHER Mess- und Regeltechnik GmbH Technical data | 6
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T
ØD2
ØD1
L2
L1
AF1
AF2
Fig.8: Cutting ring screw connection
D ØD1 ØD2 L1 L2 A/F 1 A/F 2
G⅛ 6 mm 14 mm 8 mm 23.5 mm 14 mm 14 mm
G⅛ 8 mm 14 mm 8 mm 24.5 mm 14 mm 17 mm
32
60°
1.5
6
Ø4.2
30°
30 20
5.5
10
18
50
60
Fig.9: Mounting foot

7 | Order codes FISCHER Mess- und Regeltechnik GmbH
16/20 BA_EN_DS31
7 Order codes
Process connection
Rated pressure
Version of the measuring system
Switching elements
Electric connection
Type
Measuring range
Code no.
FD S 3 1
1 2 5 6 7 83 4
[1.2] Measuring range Adjustment range
83 0 to 400 mbar 4 to 400 mbar
01 0 to 0.6 bar 0.06 to 0.6 bar
02 0 to 1 bar 0.10 to 1.0 bar
03 0 to 1.6 bar 0.16 to 1.6 bar
04 0 to 2.5 bar 0.25 to 2.5 bar
05 0 to 4 bar 0.40 to 4.0 bar
06 0 to 6 bar 0.60 to 6.0 bar
[3] Nominal pressure
FPN16
[4] Measuring system
MPressure chamber: brass Seals: NBR
NPressure chamber: brass Seals: Viton
[5.6] Process connection
00 Inner thread G⅛
20 Cutting ring connection in brass for 6 mm pipe Material steel
21 Cutting ring connection in brass for 8 mm pipe Material steel
28 Cutting ring connection in brass for 6 mm pipe Material: brass
29 Cutting ring connection in brass for 8 mm pipe Material: brass
[7] Switching Elements
A1 adjustable micro-switch Function: NO contact
B1 adjustable micro-switch Function: NC contact
[8] Electrical connection
0M16 Cable screw connection without cables
11.0 m long number cable, hard-wired
22.5 m long number cable, hard-wired
55.0 m long number cable, hard-wired

FISCHER Mess- und Regeltechnik GmbH Attachment | 8
BA_EN_DS31 17/20
8 Attachment
Fig.10: CE_DE_DS31

FISCHER Mess- und Regeltechnik GmbH
18/20 BA_EN_DS31

FISCHER Mess- und Regeltechnik GmbH
BA_EN_DS31 19/20

Mess- und Regeltechnik GmbH
Bielefelder Str. 37a
D-32107 Bad Salzuflen
Tel. [phone]
Fax [phone]
www.fischermesstechnik.de
[email protected]
Technische Änderungen vorbehalten. Subject to technical changes. Sous réserve de modifications techniques.