FISCHER DS21 User manual

Operating Manual
DS21
Differential pressure measuring and switching device
Flow guard in heat transfer oil systems in compliance with DIN 4754-2
and hot water systems according to VdTÜV Information sheet "Flow 100"
09005128 BA_EN_DS21 ST4-F 01/19 *09005128*

| Masthead FISCHER Mess- und Regeltechnik GmbH
2 / 40 BA_EN_DS21_ST4-F
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 GmbH 2015
Version history
Rev. ST4-A 09/14 Version 1 (first edition)
Rev. ST4-B 06/15 Version 2 (Correction)
Rev. ST4-C 01/16 Version 3 Flow 100, DIN CERTCO 4754-2
Rev. ST4-D 06/16 Version 4 New EU directives
Rev. ST4-E 09/16 Version 5 DIN 19216 replaces VDE/VDI 3512 sheet 1
Rev. ST4-F 01/19 Version 6 Order codes optional information (SIL)

FISCHER Mess- und Regeltechnik GmbH Table of contents
BA_EN_DS21_ST4-F iii
Table of contents
1 Safety notes................................................................................................................................................... 5
1.1 General....................................................................................................................................................5
1.2 Personnel Qualification ...........................................................................................................................5
1.3 Risks due to Non-Observance of Safety Instructions..............................................................................5
1.4 Safety Instructions for the Operating Company and the Operator ..........................................................5
1.5 Unauthorised Modification.......................................................................................................................5
1.6 Inadmissible Modes of Operation............................................................................................................5
1.7 Safe working practices for maintenance and installation work................................................................6
1.8 Pictogram explanation.............................................................................................................................6
2 Product and functional description............................................................................................................. 7
2.1 Use as intended ......................................................................................................................................7
2.2 Equipment versions.................................................................................................................................7
2.3 Function diagram.....................................................................................................................................9
2.4 Design and mode of operation ................................................................................................................9
3 Installation and assembly .......................................................................................................................... 10
3.1 General..................................................................................................................................................10
3.2 Assembly...............................................................................................................................................10
3.3 Process connection ...............................................................................................................................10
3.4 Electrical connections............................................................................................................................11
4 Commissioning ........................................................................................................................................... 13
4.1 General..................................................................................................................................................13
4.2 Display and control elements ................................................................................................................13
4.3 Lead seal...............................................................................................................................................13
4.4 Zero point correction .............................................................................................................................14
4.5 Switch point setting ...............................................................................................................................14
4.6 Function test..........................................................................................................................................14
5 Maintenance ................................................................................................................................................ 15
5.1 Wartung (maintenance).........................................................................................................................15
5.2 Transport ...............................................................................................................................................15
5.3 Service ..................................................................................................................................................15
5.4 Accessories ...........................................................................................................................................15
5.5 Disposal.................................................................................................................................................15
6 Technical data ............................................................................................................................................. 16
6.1 Input variables .......................................................................................................................................16
6.2 Output parameters ................................................................................................................................16
6.3 Measured Value Display .......................................................................................................................16
6.4 Electrical connection .............................................................................................................................16
6.5 Application conditions............................................................................................................................17
6.6 Construction design...............................................................................................................................18
6.7 Dimensional drawings ...........................................................................................................................19
7 Order Codes ................................................................................................................................................ 24

Table of contents FISCHER Mess- und Regeltechnik GmbH
iv BA_EN_DS21_ST4-F
8 Attachments .................................................................................................................................................26
8.1 EC Declaration of conformity..................................................................................................................26
8.2 EC type testing in compliance with 97/23/EC.........................................................................................28
8.3 EAC Declaration.....................................................................................................................................29
8.4 DIN CERTCO certification DIN 4754-2 ..................................................................................................30
8.5 Part test current 100...............................................................................................................................32
8.6 Type test flow limiter DIN EN 12952-11 .................................................................................................33
8.7 GL Certificate .........................................................................................................................................34
8.8 SIL Certificate.........................................................................................................................................35
8.9 RMRS Certificate....................................................................................................................................38

FISCHER Mess- und Regeltechnik GmbH Safety notes | 1
BA_EN_DS21_ST4-F 5 / 40
1 Safety notes
1.1 General
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
responsible 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 manufac-
turer 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.

1 | Safety notes FISCHER Mess- und Regeltechnik GmbH
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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).
a) 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).
a) 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).
a) Avoid danger by observing the valid safety regulations.
NOTICE Note / advice
This indicates useful information of advice for efficient and smooth operation.

FISCHER Mess- und Regeltechnik GmbH Product and functional description | 2
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2 Product and functional description
2.1 Use as intended
The unit is exclusively designed for the purpose defined by the manufacturer in
the data sheet or operating instructions.
Differential pressure measuring and switching device
The DS21 is a measuring and switch unit for measuring differential pressure
under difficult measuring conditions such as: pressure surges, vibrations, fre-
quent switching and high demands on the switching output. Please contact the
manufacturer before using this unit with dirty or aggressive media because the
unit needs to be adapted in terms of the parts that come into contact with the
media.
Flow assurance
The units in this series are used as flow guards in heat transfer oil systems in
compliance with DIN 4754-2 and hot water systems in compliance with VdTÜV
information sheet 'Flow 100'. The flow guards comprise a differential pressure
transducer, e.g. a measuring orifice, the differential pressure measuring and
switch unit and shut-off fittings. The respective installation instructions must be
observed for this application case. All units of the series DS21 satisfy these re-
quirements.
NOTICE The type tests in compliance with DIN 4754-2 and VdTÜV information sheet
"Flow 100" only apply in conjunction with a differential pressure transducer, not
for a differential pressure measuring and switching device alone.
The successful type test of the series DS21 was confirmed by means of the fol-
lowing test symbols:
▪ for flow guards in compliance with DIN 4754-2 :
DIN CERTCO registration number 10S001
▪ according to VdTÜV Information sheet "Flow 100" :
Part code TÜV . SW/SB . 15 – 020
2.2 Equipment versions
The DS21 can be supplied iwth the following different pressure chambers:
▪ Aluminium
▪ Stainless steel 1.4305
The aluminium pressure chambers can also be supplied with a HART COAT®
coating. The following shows the various unit versions. On the left-hand side
are casings with hoods (IP 55) and on the right-hand side casings with bayonet
rings (IP 65).
NOTICE Installation of front panel
Please note that the switch points of devices with bayonet rings need to be set
before mounting the front control panel. When installed, the unit can no longer
be opened.
Please see the order code [}24] for the process connection options.

2 | Product and functional description FISCHER Mess- und Regeltechnik GmbH
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2.2.1 Pressure chamber in aluminium
Pressure chamber
Hood
Process connection
Electrical connection
Bayonet ring
Pressure equalisation element
Switch panel installation kit
Assembly foot
Fig.1: DS21_Pressure chamber in aluminium [Standard]
2.2.2 Pressure chamber in stainless steel
Pressure chamber
Assembly foot
Fig.2: DS21_Pressure chamber in stainless steel [Standard]

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2.2.3 Electro connection variants
All pressure chamber types are available optionally with a permanently wired
number cable, a cable connection socket or a cable connector. The cable con-
nector has the same dimensions as the cable socket.
GL models are an exception. These are only supplied with a cable socket in-
cluding a 3 m long connection cable. The associated wiring diagrams are
shown on the type plate and in the section 'Installation and assembly'.
Numbered cables Cable connection socket
Fig.3: DS21_EL-connection variants [Standard]
2.3 Function diagram
2
1
3
4
5
6
1
7
Fig.4: DS21 Function diagram [Standard]
1 Pressure chamber 2 Motion train
3 Tappet 4 Micro-switch
5 Switch point setting 6 Measuring diaphragm
7 Measuring springs
2.4 Design and mode of operation
The basis for this measurement and switch unit is a sturdy non-sensitive dia-
phragm measuring unit that is suitable for measuring differential pressure, and
over and under-pressure. The unit uses the same measuring principle for all
three measuring applications.
In the idle position, the spring forces are equalised on both sides of the measur-
ing diaphragm. The pressure that is to be measured or the differential pressure
creates a one-sided force on the measuring diaphragm that moves the dia-
phragm system against the measuring range springs until the spring forces are
equalised. In the case of overload, the measuring diaphragm is supported by
metallic contact surfaces.
A central tappet transfers the movement of the diaphragm system onto the dis-
play mechanism and, at the same time, onto the actuation elements of the mi-
cro-switches. The switch points are set via the setting screws and refernec
value scale.

3 | Installation and assembly FISCHER Mess- und Regeltechnik GmbH
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3 Installation and assembly
3.1 General
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.
3.2 Assembly
The standard unit is designed for wall mounting. In the case of units with an alu-
minium pressure chamber, there are three mounting feet. Units with stainless
steel pressure chambers are mounted using the rear attachment plate that also
acts as a mounting foot.
A control panel installation set can be ordered for each unit that allowed install-
ation on the front of the unit.
The unit is set for vertical installation ex-works. Only this installation poistion is
allowed. To ensure safety during installation and maintenance, we recommend
installing a suitable shut-off valve on the system.
3.3 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)
Fig.5: Differential pressure con-
nection
The differential pressure connections are marked with (+) and (-) symbols on
the device. The differential pressure connection lines must be mounted accord-
ing to these symbols.
▪ (+) Higher pressure
▪ (-) Lower pressure
The differential 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 pockets are created. If the required inclination is not reached, water or air
filters must be installed at suitable places.
The differential pressure lines must be kept as short as possible and installed
without any tight bends to avoid delays.
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.
3.3.1 Installation regulations for flow guards in heat transfer units in
compliance with DIN 4754-2
In the case of differential pressure transducers in compliance with DIN 1952/
VDI 2014, the measurement must be set up in compliance with DIN 4752-2
Sec. 4.3.4.

FISCHER Mess- und Regeltechnik GmbH Installation and assembly | 3
BA_EN_DS21_ST4-F 11 / 40
Shut-off valves in differential pressure lines may only be activated with tools.
Threaded screw connections in these lines must be designed so that they re-
main tight without any sealing agent, or the connection must be welded or hard-
soldered.
The clear diameter and length of differential pressure lines must be dimen-
sioned so that wen the line is cold (approx. 20 °C), the response time of the unit
is no longer than 5 sec.
Differential pressure lines must be made of metal. Their clear width may not un-
dercut 4 mm and the stretched length must be at least 500 mm. If arranged with
block valves, the differential pressure line between the valve block and differen-
tial pressure transducer must be at least 500 mm.
Locking and unlocking conditions must be ensured during installation via the
following electrical lines.
3.3.2 Installation regulations for flow limiters in steam boilers and hot
water systems
Differential pressure transducers in compliance with DIN 1952/VDI 2041, Itabar
or Annubar probes must be used as measuring elements. The measurement
must be taken in compliance with DIN19216:1995-08.
It must be possible to block the differential pressure lines with a 5x valve block
in front of the differential pressure unit and must be designed to allow blow-out.
Shut-off valves in differential pressure lines may only be activated with tools.
Threaded screw connections in these lines must be designed so that they re-
main tight without any sealing agent, or the connection must be welded or hard-
soldered.
The differential pressure lines must be made of metal and have a clear width of
at least 8 mm. The stretched length of the differential pressure lines must be at
least 500 mm.
3.4 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.
No Contact Switch
1 Make contact NO
Switch 1
2 Break contact NC
3 Joint COM
4 Joint COM
Switch 2
5 Make contact NO
6 Break contact NC
Ground connection

3 | Installation and assembly FISCHER Mess- und Regeltechnik GmbH
12 / 40 BA_EN_DS21_ST4-F
Lid screw
Lid
Seal
Middle part
Connection terminals
Pressure screw
Pressure washer
Cutting ring
Clamping ring
Ground terminal
Seal (view from above)
Fig.6: Cable socket
Lid screw
Lid
Seal
Middle part
Plug part (socket)
Pressure screw
Pressure washer
Cutting ring
Clamping ring
Ground terminal
12
3
4
6
5
(view from below)
Fig.7: Cable plug
For models with numbered cables, the cable numbers correspond with the
presented terminal numbers.
GL version
In models with one switch, a cable (0.6/1KV 4Gx1.5) with the following color
code is connected:
Ter-
minal
Wire ID
1 grey
2 brown
3 black
green/yellow
In models with two switches, a cable (0.6/1KV 7Gx1.5) with numbers for identi-
fying the wires must be connected. The numbers of the cable correspond to the
terminal numbers of the cable socket.

FISCHER Mess- und Regeltechnik GmbH Commissioning | 4
BA_EN_DS21_ST4-F 13 / 40
4 Commissioning
4.1 General
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.
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.
4.2 Display and control elements
The illustration shows an example because the measurement scale and there-
fore also the reference value scale depend on the respective measuring range.
The position and form of the control elements are at least similar to the illustra-
tion.
Switch point setting
Switch 1
Switch point setting
Switch 2
Setting screw for the
zero point correction
Standard
value scale
Measurement scaleMeasurement display
Fig.8: Control elements [DS21]
4.3 Lead seal
It is possible to secure the unit against removal and adjustment of the switch
points by means of a lead seal. This seal may not be removed. The device can
be sealed on site or ex-works. In the latter case, the device is supplied with a
pre-setting. After this, it is no longer possible to adjust the switch point setting or
correct the zero-point.

4 | Commissioning FISCHER Mess- und Regeltechnik GmbH
14 / 40 BA_EN_DS21_ST4-F
4.4 Zero point correction
1. Load the pressue chamber with the existing static system pressure.
2. Open the unit either by removing the hood or the bayonet ring and the front
disk. Use a wrench to mount or remove the bayonet ring to prevent damage
to the casing.
3. Set the measurement display with the setting screw for correcting the zero-
point to the zero-point of the measurement scale.
4. Close the unit.
4.5 Switch point setting
1. Open the unit either by removing the hood or the bayonet ring and the front
disk. Use a wrench to mount or remove the bayonet ring to prevent damage
to the casing.
2. Use a screwdriver to set the required switch points in compliance with the
markings on the standard value scale.
3. Close the unit.
NOTICE Setting accuracy
The achieveable setting accuracy with the standard value scale is ± 5 %.
A higher level of precision can only be achieved using suitable units such as
test manometers, ohmmeters etc. Optionally, these devices can be pre-installed
ex-works.
4.6 Function test
Open the unit either by removing the hood or the bayonet ring and the front
disk.
If the unit has two switch points, the stated test steps must be carried out for
both switches.
After the test, the switch points need to be reset (see above).
NOTICE Lead seal
It is possible to secure the bayonet ring or the hood against removal by means
of a lead seal. This seal may not be removed. A function test can only be car-
ried out in this case by changing the operating pressure (see below).
4.6.1 Checking the switch points in a depressurized state
No measurement is shown and the measurement display point to zero.
Turn the switch point setting button toward the zero-point until the micro-switch
is activated.
4.6.2 Checking the switch points when the system is operational
A measurement is shown. If despite operational pressure, no measurement is
shown, you can generate a differential pressure by blocking the differential
pressure line on one side.
Turn the switch point setting button toward the measurement until the micro-
switch is activated.
4.6.3 Checking the switch points by changing the operartional pressure
If the unit is sealed or the switch point setting cannot be changed for any other
reason, you can carry out a function test by changing the operational pressure.
Set the differential pressure so that the micro-switch(es) are activated.

FISCHER Mess- und Regeltechnik GmbH Maintenance | 5
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5 Maintenance
5.1 Wartung (maintenance)
The unit is maintenance-free apart from regular cleaning of the surface of the
casing.
WARNING Dust deposits
The casing of the unit must be cleaned regularly with a damp cloth to prevent
heat accumulation, as this can lead to the surface overstepping the maximum
allowed temperature (T70 °C). The cleaning frequency depends on the amount
of dust in the location.
To ensure reliable operation and a long service life, we recommend carrying out
the following test on a regular basis:
▪ Check the reading.
▪ Checking the switch function in connection with the downstream compon-
ents.
▪ Checking the differential pressure lines for leaks.
▪ Checking the electrical connections (terminal connection of the cable).
The precise test cycles and operating and ambient conditions need to be adjus-
ted. If several components of the unit interact, all operating instructions of the
other units also need to be observed.
5.2 Transport
The measuring device must be protected against impacts. It should be trans-
ported 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 Accessories
Recommended shut-off fitting
▪ DZ23 Three-spindle equalisation and shut-off valve
Art.No. DZ2300H ###
For casing material and pressure connection, see data sheet
▪ DZ23 Four-spindle equalisation and shut-off valve with venting valve
Art.No. DZ2400H ###
For casing material and pressure connection, see data sheet
5.5 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.

6 | Technical data FISCHER Mess- und Regeltechnik GmbH
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6 Technical data
Please also observe the order code here.
6.1 Input variables
Measuring variable Differential, over and under-pressure for gaseous and fluid media.
Measurement range Measurement range Allowed static operating pressure
0 … 250 mbar 6 bar
0 … 400 mbar 6 bar
0 … 0.6 bar 10 bar
0 … 1 bar 16 bar
0…1.6 bar 16 bar
0…2.5 bar 16 bar
0 … 4 bar 16 bar
0 … 6 bar 16 bar
Rated pressure of the
measuring system
25 bar
Max. pressure load Over-pressure-proof on one side up to rated pressure of the measuring system,
(+) and (-) sides, under-pressure-proof
6.2 Output parameters
Switching outputs 1 or 2 micro-switches with 1-pin changeover contact.
Switch point setting After opening the casing using the setting screw and reference value scale.
Smallest settable value approx. 5% of the end value of the measuring range.
Reproducibility The reproducibility of the switch-point setting corresponds to the measuring pre-
cision.
Switch hysteresis approx. 2.5% of the upper range value
Load data/contact AC DC
Max. switching voltage Umax 250V 30V
Max. switching current Imax 5A 0.4A
max. switching output Pmax 250 VA 10 W
6.3 Measured Value Display
Anzeige Indicator with measurement scale
Measurement accuracy ± 2.5% of the upper range value
6.4 Electrical connection
▪ Cable socket
screw terminal up to 1.5 mm2 with wire protection
Contact material Ms gold-flashed
Cable screw connection M20 x 1.5
▪ Cable connector
screw terminal up to 1.5 mm2 with wire protection
Contact material Ms nickel-plated
Cable screw connection M20 x 1.5
▪ Number cable
4 x 0.75 mm2 YSLY-JZ
strand end with clip, wire ID 1,2,3, gn/ge

FISCHER Mess- und Regeltechnik GmbH Technical data | 6
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1
6
54
3
2
Fig.9: Cable socket / cable plug
No Contact Switch
1 Make contact NO
Switch 1
2 Break contact NC
3 Joint COM
4 Joint COM
Switch 2
5 Make contact NO
6 Break contact NC
Ground connection
GL version In models with one switch, a cable (0.6/1KV 4Gx1.5) with the following color
code is connected:
Ter-
minal
Wire ID
1 grey
2 brown
3 black
green/yellow
In models with two switches, a cable (0.6/1KV 7Gx1.5) with numbers for identi-
fying the wires must be connected. The numbers of the cable correspond to the
terminal numbers of the cable socket.
6.5 Application conditions
Ambient conditions Allowed ambient temperatures -10 °C … +70 °C
Allowed temperature of the medium -10 °C … +85 °C *)
Enclosure protection class
(depending on model)
IP 55 or
IP 65 in compliance with DIN EN
60529
*) The temperature in the unit may not exceed +70 °C.
EC Declaration of conform-
ity
Low-Voltage Directive 2014/35/EU
Pressurised Vessel Directive 2014/68/EU
RoHS Directive 2011/65/EU

6 | Technical data FISCHER Mess- und Regeltechnik GmbH
18 / 40 BA_EN_DS21_ST4-F
Certificates Type testing (Module B) No. 07 202 1081 Z 9142/13/H
Quality assurance system (Module D) No. 07/202/1081 /Z/0095/18/D/001
EAC Declaration No TC RU д-DE.AB71.B.09656
DIN CERTCO DIN 4754-2:2015-03
No. 10S001
VdTÜV Data sheet flow 100
TÜV SW/SB 15-020
DNV GL No. 93 823 – 88 HH
SIL 2**) Nr. 44 799 13759902
**) Only for devices with the order code for SIL (optional information).
6.6 Construction design
Process connection Inner thread G¼
Cutting ring screw connection in steel for 6, 8, 10, 12 mm pipe
Cutting ring screw connection in stainless steel 1.4571 for 6, 8, 10, 12 mm pipe
Measuring system Pressure spring measuring diaphragm system
Weight Pressure chamber in aluminium: approx. 1.2 kg
Pressure chamber in CrNi steel: approx. 3.5 kg
6.6.1 Materials
Pressure chamber Aluminium Gk-AlSi10Mg, painted black
Aluminium Gk-AlSi10MG with HART-COAT© Surface protection
CrNi steel 1.4305
Measuring diaphragm Fabric-reinforced VITON®
Gaskets VITON®
Inner parts in contact with
the medium
CrNi-steel 1.4310, 1.4305
Hood Polycarbonate (PC) Makrolon®
Bayonet ring CrNi-Steel 1.4305
Front pane Safety laminated glass
6.6.2 Assembly
Wall mounting
Mounting the control panel

FISCHER Mess- und Regeltechnik GmbH Technical data | 6
BA_EN_DS21_ST4-F 19 / 40
6.7 Dimensional drawings
(All dimensions in mm unless otherwise stated)
6.7.1 Pressure chamber in aluminium
Cable screw connection
plastic M16x1.5
Cable screw connection
plastic M20x1.5
Cutting ring
screw connection
Process connection
inner thread
min.
17
Ø5
77
30°
30°
82
Ø127
Bolt circle - Ø116
44
Ø104
26
101
108
92
G¼
Ø21
0.8
13.5
96
min. 3
10
Bolt circle - Ø116
Cutout - Ø104
Ø132
Fig.10: Pressure chamber in aluminium (IP55)

6 | Technical data FISCHER Mess- und Regeltechnik GmbH
20 / 40 BA_EN_DS21_ST4-F
Cable screw connection
plastic M20x1.5
Cutting ring
screw connection
Process connection
inner thread
Ø5 73
79
60°
89 77
Ø127
Bolt circle - Ø116
17
26
108
Ø101
min. 3
102
Bolt circle - Ø116
Cutout - Ø104
Ø132
13.5
0.8
G¼
Ø21
Fig.11: Pressure chamber in aluminium (IP65)