Knick SensoGate WA131MH User manual

User Manual SensoGate WA131MH
Manual Retractable Fitting
www.knick.de
Read before installation.
Keep for future use.

SensoGate WA131MH
ii
Supplemental Directives
These supplemental directives explain how safety information is laid out in this document and what
content it covers.
Safety Chapter
This document's safety chapter is designed to give the reader a basic understanding of safety. It illus-
trates general hazards and gives strategies on how to avoid them.
Warnings
SensoGate WA131MH was subjected to a risk assessment. Nevertheless, not all risks can be sufficiently
reduced. This document uses the following warnings to indicate hazardous situations:
Symbol Category Meaning Remark
WARNING Designates a situation that can lead to death or serious
(irreversible) injury
The warnings contain
information on how
to avoid the hazard.
CAUTION Designates a situation that can lead to slight or moderate
(reversible) injury
Without NOTICE Designates a situation that can lead to property or environ-
mental damage
Symbols Used in this Document
Symbol Meaning
Cross-reference to content within this document
Interim or final results in instructions for action
Item number in figure
Item number in text

SensoGate WA131MH
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Table of Contents
1 Safety............................................................................................................................................. 5
1.1 Intended Use.......................................................................................................................................................... 5
1.2 Personnel Requirements.................................................................................................................................... 5
1.3 Safeguards .............................................................................................................................................................. 6
1.4 Residual Risks......................................................................................................................................................... 7
1.4.1 Environmental Influences .................................................................................................................... 7
1.4.2 Accidental Loosening of the Process Connection....................................................................... 7
1.5 Safety Accessories ................................................................................................................................................ 7
1.6 Hazardous Substances........................................................................................................................................ 8
1.7 Operation in Explosive Atmospheres............................................................................................................ 8
1.7.1 Possible Ignition Hazards During Installation and Maintenance........................................... 8
1.7.2 Possible Ignition Hazards During Operation................................................................................. 9
1.8 Safety Training....................................................................................................................................................... 9
1.9 Maintenance and Spare Parts .......................................................................................................................... 9
2 Product.......................................................................................................................................... 10
2.1 Package Contents................................................................................................................................................. 10
2.2 Product Identification......................................................................................................................................... 10
2.2.1 Example of a Version.............................................................................................................................. 10
2.2.2 Product Code............................................................................................................................................ 11
2.3 Nameplates............................................................................................................................................................. 12
2.4 Symbols and Markings ....................................................................................................................................... 14
2.5 Design and Function ........................................................................................................................................... 14
2.5.1 Retractable Fitting .................................................................................................................................. 15
2.5.2 Drives and Sensor Holders................................................................................................................... 16
2.5.3 Process Connections.............................................................................................................................. 16
2.5.4 Immersion Tube....................................................................................................................................... 17
2.6 Permissible Changes ........................................................................................................................................... 17
2.7 Limit Positions ....................................................................................................................................................... 18
2.7.1 SERVICE and PROCESS Position ......................................................................................................... 18
2.7.2 Limit Switch............................................................................................................................................... 19
3 Installation.................................................................................................................................... 20
3.1 Retractable Fitting: Installation ....................................................................................................................... 20
3.2 Safety Accessories: Installation........................................................................................................................ 20
3.3 Outlet Hose: Installation .................................................................................................................................... 21
3.4 Inlet Hose: Installation ........................................................................................................................................ 21
4 Commissioning............................................................................................................................. 22
5 Operation ...................................................................................................................................... 23
5.1 Moving into the PROCESS Position................................................................................................................ 23
5.2 Moving into the SERVICE Position.................................................................................................................. 24

SensoGate WA131MH
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5.3 Installing and Removing a Sensor.................................................................................................................. 25
5.3.1 Safety Instructions on Installing and Removing Sensors ......................................................... 25
5.3.2 Solid-Electrolyte Sensor, Short Immersion Depth: Installation .............................................. 25
5.3.3 Solid-Electrolyte Sensor, Short Immersion Depth: Removal ................................................... 26
5.3.4 Liquid-Electrolyte Sensor: Installation............................................................................................. 27
5.3.5 Liquid-Electrolyte Sensor: Removal.................................................................................................. 28
6 Maintenance ................................................................................................................................. 29
6.1 Inspection ............................................................................................................................................................... 29
6.1.1 Inspection and Maintenance Intervals............................................................................................ 29
6.1.2 Knick Premium Service.......................................................................................................................... 29
6.1.3 Immersion Lock Without a Mounted Solid-Electrolyte Sensor: Functional Test .............. 29
6.1.4 Immersion Lock Without a Mounted Liquid-Electrolyte Sensor: Functional Test............ 30
6.2 Maintenance .......................................................................................................................................................... 30
6.3 Corrective Maintenance..................................................................................................................................... 31
6.3.1 Corrective Maintenance Safety Instructions ................................................................................. 31
6.3.2 Drive Unit: Disassembly ........................................................................................................................ 31
6.3.3 Drive Unit: Assembly.............................................................................................................................. 32
6.3.4 Immersion Tube: Removal ................................................................................................................... 33
6.3.5 Immersion Tube: Installation .............................................................................................................. 34
6.3.6 Calibration Chamber: Removal .......................................................................................................... 35
6.3.7 Calibration Chamber: Installation ..................................................................................................... 36
6.3.8 Knick Repair Service ............................................................................................................................... 36
7 Troubleshooting ........................................................................................................................... 37
7.1 Malfunction States ............................................................................................................................................... 37
7.2 Retractable Fitting: Emergency Release....................................................................................................... 38
8 Removal from Operation ............................................................................................................. 39
8.1 Retractable Fitting: Removal............................................................................................................................ 39
8.2 Returns ..................................................................................................................................................................... 39
8.3 Disposal.................................................................................................................................................................... 39
9 Spare Parts, Accessories, and Tools............................................................................................. 40
9.1 Gasket Sets.............................................................................................................................................................. 40
9.2 Spare Parts .............................................................................................................................................................. 43
9.3 Accessories.............................................................................................................................................................. 44
9.4 Tools .......................................................................................................................................................................... 47
10 Dimension Drawings.................................................................................................................... 48
11 Specifications................................................................................................................................ 53
Appendix....................................................................................................................................... 54
Glossary......................................................................................................................................... 56
Index.............................................................................................................................................. 57

SensoGate WA131MH
5
1 Safety
The following safety instructions contain the necessary information for the safe use of the product. If
you have any questions, please contact Knick Elektronische Messgeräte GmbH & Co. KG using the in-
formation provided on the back page of this document.
1.1 Intended Use
SensoGate WA131MH is a retractable fitting for installation in boilers, tanks, and pipes. The product is
used to accommodate a sensor for measuring process parameters. SensoGate WA131MH allows the
sensor to move into the process medium. Moving to the SERVICE or PROCESS position must be per-
formed manually. While the process is in operation, the sensor can be replaced in the SERVICE position.
The defined operating conditions must be observed when using this product. ➜Specifications, p. 53
Thanks to its modular design, SensoGate WA131MH can be adapted to changed conditions by the
customer. ➜Permissible Changes, p. 17
Using the product improperly or for any purpose other than the product's intended purpose is not
permitted and may result in injury to persons or damage to objects or the environment.
The SensoGate WA131MH-X version is certified for operation in explosive atmospheres.
➜Operation in Explosive Atmospheres, p. 8
When installed, SensoGate WA131MH can be sterilized with steam. An independent testing institute
evaluated the product in terms of its sterilizability.1)
1.2 Personnel Requirements
The personnel must be authorized by the operating company and instructed in handling this product.
The operating company must ensure that personnel are sufficiently qualified in accordance with the
local and national codes and regulations that apply for the area in which the product is being used.
Knick recommends the following minimum personnel qualifications:
Qualified personnel Recommended minimum qualification
Operating personnel Installing and operating machines and industrial plants
Detecting and eliminating minor malfunction states
Ensuring the operability of technical systems based on product documentation
Installation and
maintenance
personnel
Assembling, disassembling, maintaining, monitoring, and repairing electrical machines,
drive systems, and components in the automation industry
Installing cables and electrical equipment as an authorized and licensed electrician
Systematically troubleshooting and eliminating errors in electrical systems
Assessing processes and equipment with respect to the applicable safety and environ-
mental codes and regulations
See also
➜Safety Training, p. 9
1) TNO report V7942 dated February 25, 2008, www.tno.nl

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1.3 Safeguards
1
2
Dismount Guard for the Solid-Electrolyte Sensor
When using SensoGate WA131MH versions for solid-electrolyte
sensors, sensors can only be removed in the SERVICE position.
➜Limit Positions, p. 18
When in the SERVICE position, the sensor is located in the protec-
tion sleeve (1) or the extension (2) and is not accessible.
Immersion Lock Without a Mounted Solid-Electrolyte Sensor
A mechanical lock prevents a SensoGate WA131MH without a
mounted solid-electrolyte sensor from being moved into the
PROCESS position.
The safety lock button cannot be depressed. The rotating collar is
mechanically locked and cannot be rotated.
Information on the immersion lock is provided on a safety label.
The safety label is attached to the strain relief bracket of the
SensoGate WA131MH.
1
2
Immersion Lock Without a Mounted Liquid-Electrolyte Sensor
The safeguard is only available with special version V.
➜Product Code, p. 11
The immersion lock can be seen at the yellow indicator ring (2)
above the bellows(1). If the yellow indicator ring (2) is missing, the
safeguard function is not available.
A mechanical lock prevents a SensoGate WA131MH without a
mounted liquid-electrolyte sensor from being moved into the
PROCESS position.
The safety lock button cannot be depressed. The rotating collar is
mechanically locked and cannot be rotated.
1
2
Leakage Bores
The calibration chamber (1) is provided with three radial leakage
bores (2).
Process medium escaping from the leakage bores (2) is indicative
of damage to the calibration chamber’s O-rings. This damage can
be detected and repaired.

SensoGate WA131MH
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The availability of safeguards is in part dependent on the version of SensoGate WA131MH.
➜Product Code, p. 11
Environmental influences may affect the functionality of safeguards (e.g. components stuck together
by process medium). ➜Residual Risks, p. 7
1.4 Residual Risks
The product has been developed and manufactured in accordance with generally accepted safety
rules and regulations. However, it is not possible to rule out all risks.
1.4.1 Environmental Influences
The effects of moisture, ambient temperature, chemicals, and corrosion can negatively impact the safe
operation of the product. Please observe the following instructions:
• Only operate SensoGate WA131MH in compliance with the stated operating conditions.
➜Specifications, p. 53
• If possible, install the product inside a protected area of the plant. Alternatively, take appropriate
measures to protect the SensoGate WA131MH (e.g. install ZU0759protective cap 1)).
➜Accessories, p. 44
• If using aggressive chemical process media, adjust the inspection and maintenance intervals
accordingly. ➜Inspection, p. 29
• Adhering and sticky process media can impact the functionality of SensoGate WA131MH (e.g.,by
causing components to stick together). Adjust the inspection and maintenance intervals accord-
ingly. ➜Inspection, p. 29
1.4.2 Accidental Loosening of the Process Connection
The coupling nut of the screw joint on process connections with a thread may become loose by acci-
dent. This may be caused by manual rotation of the rotating collar when moving to the limit positions
or by process-related vibrations.
Pressurized process medium may escape. Use of an appropriate retainer clamp or locking clamp is
strongly recommended. ➜Safety Accessories, p. 7
Operating SensoGate WA131MH without a retainer or locking clamp is at the risk of the operating
company. The operating company must take action to rule out the possibility of the screw joint cou-
pling nut accidentally loosening.
1.5 Safety Accessories
Specially developed accessories are available to increase safety. ➜Accessories, p. 44
ZU0818 Retainer Clamp for Ingold Socket, 25 mm
The retainer clamp prevents the coupling nut of the Ingold socket (25 mm) screw
joint from accidentally loosening.
The wires of the retainer clamp connect SensoGate WA131MH to the customer’s
process port. A locking lug on the retainer clamp engages in the groove of the
coupling nut (form-fit).
1) The ZU0759 protective cap protects against the effects of weather exposure and prevents the ingress of external
liquids or particles into the area of the sensor connections.

SensoGate WA131MH
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1.6 Hazardous Substances
In certain situations (e.g. sensor replacement or corrective maintenance), personnel may come into
contact with the following hazardous substances:
• Process medium
• Calibration or cleaning medium
• Lubricant
The operating company is responsible for conducting a risk assessment.
See the relevant manufacturer’s safety data sheets for hazard warnings and safety instructions on
handling hazardous substances.
1.7 Operation in Explosive Atmospheres
The SensoGate WA131MH-X is certified for operation in explosive atmospheres.
• EU-Type Examination Certificate KEMA07ATEX0065
Exceeding the standard atmospheric conditions within the manufacturer’s specifications, such as am-
bient temperature, process pressure and temperature, does not impair the durability of the retractable
fittings.
Related certificates are included in the product’s scope of delivery and are available at www.knick.de
in the current version.
Observe all applicable local and national codes and standards for the installation of equipment in ex-
plosive atmospheres. For further guidance, consult the following:
• IEC60079-14
• EU directives 2014/34/EU and 1999/92/EC(ATEX)
1.7.1 Possible Ignition Hazards During Installation and Maintenance
To avoid mechanically generated sparks, handle the SensoGate WA131MH-X with care and apply suit-
able measures, e.g., use covers and pads.
The metallic parts of the SensoGate WA131MH-X must be connected to the plant’s equipotential
bonding using the metallic process connection and the grounding connection provided for that pur-
pose.
When components are replaced with genuine Knick spare parts made of other materials (e.g. O-rings),
the information given on the nameplate may deviate from the actual version of the SensoGate
WA131MH-X. The operating company must assess and document this deviation.
➜Nameplates, p. 12
Electrostatic charging
The drive unit of specific versions of the SensoGate WA131MH-X contains housing components made
of non-conductive plastic. Due to their surface, the housing components may build up an electrostatic
charge. To prevent this charge from becoming an effective ignition source in Zone0, ensure that the
following conditions are met:
• Highly efficient charge generating mechanisms are excluded
• Non-metallic components are cleaned with a moist cloth only

SensoGate WA131MH
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Mechanically generated sparks
Single impacts on metal parts or collisions between metal parts of the SensoGate WA131MH-X are not
a potential ignition source only if the following conditions are met:
• Possible impact velocity is less than 1 m/s
• Possible impact energy is less than 500 J
If these conditions cannot be ensured, the operating company must reassess single impacts on metal
parts or collisions between metal parts as potential sources of ignition. The operating company must
implement suitable risk minimization measures, e.g., by ensuring a non-explosive atmosphere.
1.7.2 Possible Ignition Hazards During Operation
When using non-water-based cleaning, rinsing, or calibration media with a low conductivity of less
than 1nS/m, electrostatic charging of internal, conductive components may occur. The operating
company must assess the associated risks and implement appropriate measures.
The sensors that are used must be approved for operation in hazardous locations. Further information
can be found in the sensor documentation.
1.8 Safety Training
Upon request, Knick Elektronische Messgeräte GmbH & Co. KG will provide safety instruction and
product training during initial commissioning of the product. Further information is available from the
relevant Knick representatives.
1.9 Maintenance and Spare Parts
Preventive Maintenance
Preventive maintenance can keep the product in good condition and minimize downtimes. Knick pro-
vides recommended inspection and maintenance intervals. ➜Maintenance, p. 29
Lubricants
Only lubricants approved by Knick have the necessary properties to ensure trouble-free operation of
the SensoGate WA131MH. Special applications or upgrades to special lubricants are available on re-
quest. ➜Maintenance, p. 30
Tools and Mounting Aids
Special and accessory tools help maintenance personnel to replace components and wear parts safely
and professionally. ➜Tools, p. 47
Spare Parts
Genuine Knick spare parts are available for professional corrective maintenance of the SensoGate
WA131MH. ➜Spare Parts, p. 43
Repair Service
The Knick Repair Service offers professional corrective maintenance on the SensoGate WA131MH to
the original quality. Upon request, a replacement unit can be obtained for the period of the repair.
Further information can be found at www.knick.de.

SensoGate WA131MH
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2 Product
2.1 Package Contents
• SensoGate WA131MH in the version ordered
• Outlet hose
• Inlet hose 1)
• User Manual
• As applicable, supplementary datasheet for special versions 1)
• EU Declaration of Conformity
• EU-Type-Examination Certificate 1)
2.2 Product Identification
The different versions of the SensoGate WA131MH are coded in a product code.
The product code is stated on the nameplate, the delivery note, and the product packaging.
➜Nameplates, p. 12
2.2.1 Example of a Version
Basic device with manual drive, stainless steel, hygienic WA131MH – X 0 E H H 1 A A 2 2 – 0 0 0
Explosion protection ATEX Zone0 X –
Sensor Sensor, Ø 12mm with PG 13.5 0 –
Gasket material EPDM – FDA E –
Wetted materials 1.4404 / 1.4404 / 1.4404 H –
Process connections Ingold socket, hygienic, 1.4404, 25mm H 1 –
Immersion depth Short A –
Electrical limit signal Without A –
Rinse media connection Inlet G1/8 (female) and inlet hose, complete(5m),
outlet G1/8(female) with outlet hose, complete(3m) 2 –
Housing material Stainless steel / PEEK (<10bar operating pressure) 2 –
Special version Without – 0 0 0
1) Delivery is dependent on the ordered version of SensoGate WA131MH ➜Product Code, p. 11

SensoGate WA131MH
11
2.2.2 Product Code
Basic device with manual drive, stainless steel, hygienic WA131MH –__________–___
Explosion protection ATEX Zone 0 X –
Without N –
Sensor Sensor, Ø 12mm with PG 13.5 0 –
pH sensor Ø 12mm with pressurization unit,
pressure chamber for compressed air supply 1 –
Optical sensor, Ø 12mm with PG 13.5 4 –
pH sensor Ø 12mm with PG 13.5 and
lateral electrolyte refill opening 9 –
Gasket material EPDM – FDA E –
FKM – FDA F –
FFKM / EPDM – FDA G –
FFKM – FDA H –
EPDM – FDA – USP VI1) U –
FFKM – FDA – USP VI1) W –
Wetted materials2) 1.4404 / 1.4404 / 1.4404 H –
Process Connections Ingold socket, 1.4404, 25mm H 0 –
Ingold socket, hygienic, 1.4404, 25mm H 1 –
Ingold socket, 1.4435, 25mm, groove: 45mm1) H Z –
Dairy pipe DN 40 C 0 –
Dairy pipe DN 50 C 1 –
Dairy pipe DN 65 C 2 –
Dairy pipe DN 80 C 3 –
Dairy pipe DN 100 C 4 –
Clamp 1.5", 1.4404 J 1 –
Clamp 2", 1.4404 J 2 –
Clamp 2.5", 1.4404 J 3 –
Clamp 3", 1.4404 J 4 –
Clamp 3.5", 1.4404 J 5 –
Clamp 4", 1.4404 J 6 –
BioControl, 1.4404, DN 50 L 1 –
BioControl, 1.4404, DN 65 L 2 –
Varivent 1.4404 (≥ DN 50) V 1 –
Varivent 1.4404 (≥ DN 65 short, ≥ DN 80 long) V 2 –
Varivent 1.4404, inclined 12° (≥ DN 50)1) V 4 –
Immersion depth Short A –
Long B –
Electrical limit signal Without A –
With B –
Rinse media connection Inlet G1/8 (female),
outlet G1/8 (female) with outlet hose, complete(3m) 1 –
Inlet G1/8 (female) and inlet hose, complete(5m),
outlet G1/8(female) with outlet hose, complete(3m) 2 –
1) Special option, lead time on request
2) Material combinations: process-wetted part of calibration chamber / rinse-wetted part of calibration chamber / im-
mersion tube

SensoGate WA131MH
12
Basic device with manual drive, stainless steel, hygienic WA131MH –__________–___
Housing material Stainless steel / PP (< 6bar operating pressure),
not for superheated steam 1 –
Stainless steel / PEEK (<10bar operating pressure) 2 –
Special version Without – 0 0 0
Equipped with special grease (provided by customer) – 0 0 1
Customer-specific special datasheet – 0 0 F
Immersion lock for fitting without mounted sensor.
For immersion depths A, B, and pH sensor type 1. – 0 0 V
2.3 Nameplates
The SensoGate WA131MH is identified on the drive unit and the process unit by nameplates. The infor-
mation provided on the nameplates varies according to the version of the SensoGate WA131MH.
Nameplate, Version Without Ex Approval
Note: The figure shows a nameplate for the SensoGate WA131MH-N version by way of example.
Type
Made in Germany
SensoGate ®
No.
Insertion fitting
Tamb Made in Germany
-10 to 70 °C
Type
No.
SensoGate®
Retractable probe / Drive unit
WA131MH-N0E***AA*1-000
2203715 / 1909
WA131MH-N*EHH1**1*-000
2203713 / 1906
1
2
3
4
5
10
9
8
7
6
10
8
7
5
3
4
9
1Drive unit nameplate 6Permissible ambient temperature
2Process unit nameplate 7Serial number / year and week of production
3Product name 8Model designation (product code)
4CE marking 9Assembly designation
5Designation of origin 10 Name of manufacturer

SensoGate WA131MH
13
Nameplate, Version With Ex Approval
Note: The figure shows a nameplate for the SensoGate WA131MH-X version by way of example.
0044
Made in Germany
For Ex specs see drive unit
KEMA 07 ATEX 0065
SensoGate®
Type
No.
Insertion fitting
WA131MH-X*EHH1**2*-000
2203712 / 1906
WA131MH-X0E***AA*2-000
2203714 / 1909
1
2
3 4
3 6
5
6
7
8
7
5
17
18
17
16
15
14
13
18
16
15
11
12 11 10 9
12 8
1Drive unit nameplate 10 ATEX scope of application, zone, explosion group
2Process unit nameplate 11 Designation of origin
3Product name 12 EU-Type-Examination Certificate test number
4IP protection 13 Information on explosion protection
5ATEX marking 14 Permissible ambient temperature
6Special conditions and danger points 15 Serial number / year and week of production
7CE marking with identification number 16 Model designation (product code)
8Reference to additional information 17 Assembly designation
9Address of manufacturer 18 Name of manufacturer

SensoGate WA131MH
14
2.4 Symbols and Markings
Special conditions and danger points! Observe the safety information and instructions on safe use of the
product as outlined in the product documentation.
CE marking with identification number of the notified body involved in the production control.
ATEX marking1) of the European Union for operation of SensoGate WA131MH-X in explosive atmos-
pheres. ➜Operation in Explosive Atmospheres, p. 8
IP66 protection: The product is dust-tight and offers complete protection against contact as well as pro-
tection against strong water jets.
Safety lock button marked “PRESS”. Used to unlock the SensoGate WA131MH at the limit positions for the
purpose of moving to the SERVICE or PROCESS position.
Symbol indicating the direction of rotation to move the SensoGate WA131MH to the PROCESS position.
➜Moving into the PROCESS Position, p. 23
Symbol indicating the direction of rotation to move the SensoGate WA131MH to the SERVICE position.
➜Moving into the SERVICE Position, p. 24
Outlet symbol marking the outlet port of the SensoGate WA131MH.
Inlet symbol marking the inlet port of the SensoGate WA131MH.
2.5 Design and Function
SensoGate WA131MH consists of two main assemblies:
• Drive unit
• Process unit
The drive unit is connected to the process unit with a coupling nut. The drive unit and process unit can
be separated. ➜Drive Unit: Disassembly, p. 31
Various different versions of drive and process unit can be combined. ➜Permissible Changes, p. 17
The process connection is used to fasten the SensoGate WA131MH to the process port.
Manually rotating the rotating collar makes the drive unit move SensoGate WA131MH to the SERVICE
or PROCESS position. ➜Limit Positions, p. 18
1) Availability is dependent on the ordered version. ➜Product Code, p. 11

SensoGate WA131MH
15
2.5.1 Retractable Fitting
Note: The figure shows an example version of the SensoGate. ➜Product Code, p. 11
1
2
14
13
12
3
4
5
6
7
8
9
10
11
1Drive unit 8Inlet port
2Process unit 9Immersion tube
3Protection sleeve 10 Process connection (e.g., Ingold socket)
4Strain relief bracket (with grounding connection) 11 Calibration chamber, base
5Rotating collar 12 Calibration chamber, top
6Coupling nut 13 Leakage bore
7Outlet port 14 Safety lock button

SensoGate WA131MH
16
2.5.2 Drives and Sensor Holders
Note: The figure shows a selection from the product line. ➜Product Code, p. 11
1 2
1Drive, short ID 1), solid-electrolyte sensor (225mm) 2Drive, short ID 1), liquid-electrolyte sensor (250mm)
2.5.3 Process Connections
Note: The figure shows a selection from the product line. ➜Product Code, p. 11
1 2 3
4
5
1Dairy-pipe screw joint 4BioControl
2Tri-Clamp 5Ingold socket
3Varivent
1) ID = immersion depth

SensoGate WA131MH
17
2.5.4 Immersion Tube
1
1Stainless steel immersion tube 1.4404(135mm)
2.6 Permissible Changes
SensoGate WA131MH can be adapted to changed conditions by the customer. Prior to making any
changes, contact Knick Elektronische Messgeräte GmbH & Co. KG. The following are examples of possi-
ble changes:
• Change to a different process connection ➜Process Connections, p. 16
• Replacement of gaskets with other material characteristics ➜Product Code, p. 11
• Modification of the sensor holder to fit another sensor type ➜Drives and Sensor Holders, p. 16
• Retrofit of safeguards, e.g. “Immersion lock without a mounted liquid-electrolyte sensor”
➜Safeguards, p. 6
Any changes may result in deviations between the information on the nameplate and the actual ver-
sion of the SensoGate WA131MH. The operating company is responsible for evaluating the permissi-
bility of the changes and for documenting and identifying the modified version.
It is recommended that changes to the SensoGate WA131MH are carried out by the Knick Repair Ser-
vice. After making the necessary changes, a functional and pressure test is carried out and, if neces-
sary, a modified nameplate is attached.
More information on changes can be found in the related supplementary datasheet. Maintenance in-
structions with detailed instructions for action are available on request.
See also
➜Corrective Maintenance, p. 31
➜Knick Repair Service, p. 36

SensoGate WA131MH
18
2.7 Limit Positions
2.7.1 SERVICE and PROCESS Position
SensoGate WA131MH can assume two limit positions (SERVICE or PROCESS position).
SERVICE position
• The sensor is not in contact with the process medium.
• The sensor can be installed, removed, and, as necessary, cleaned while the process is running.
• The measuring system can be calibrated and adjusted.
PROCESS position
• The sensor is in contact with the process medium.
• The desired process parameters can be measured.
When using versions of SensoGate WA131MH with electronic limit signal, a contact is closed when a
limit position is reached at the limit switch. An electrical signal, e.g. at the control center, can be dis-
played when the limit position is reached. ➜Limit Switch, p. 19
The limit positions are indicated in different ways depending on the version of SensoGate WA131MH
used.
Solid-electrolyte sensor,
short immersion depth
Liquid-electrolyte sensor,
short immersion depth
1
2
3
1
2
4
SERVICE PROCESS SERVICE PROCESS
In the SERVICE position, the sensor head (3) is visible at
the top end of the protection sleeve.
In the SERVICE position, the bellows (4) are expanded.
In the PROCESS position, the sensor head (3) is retracted
into the protection sleeve.
In the PROCESS position, the bellows (4) are compressed.
In both limit positions, the rotating collar(2) is locked
and the safety lock button (1) is not depressed.
In both limit positions, the rotating collar(2) is locked
and the safety lock button (1) is not depressed.

SensoGate WA131MH
19
2.7.2 Limit Switch
Note: The limit switch is only available on versions of SensoGate WA131MH with electronic limit
signal. ➜Product Code, p. 11
The limit switch(1) is a “simple apparatus” as defined in EN 60079-11 for use in explosive atmospheres
up to Zone0.
The limit switch(1) includes two reed switches (normally-open contacts), each of which is protected
by a 30Ω series resistor.
Note: Reed switches are sensitive to transient overruns of the limit values (e.g., due to cable capaci-
tance or inductance).
The limit switch(1) has the following characteristics:
• Need not be marked according to EN60079
• For connection to intrinsically safe circuits only
• Connection and ambient conditions:
◦Ui = 30V
◦Ii = 100mA
◦Pi = 750mW
◦Ci = negligibly low
◦Li = negligibly low
Temperature class T6 T6 T5 T5
Equipment protection
level
Ga Gb Ga Gb
Ambient temperature
range
-10°C ... +45°C
14°F … 113°F
-10°C ... +60°C
14°F … 140°F
-10°C ... +57°C
14°F … 134.6°F
-10°C ... +70°C
14°F … 158°F
• Isolation voltage: 500VAC between housing and terminals
• When installed, its stainless steel housing is grounded via the SensoGate WA131MH.
• Verify the intrinsic safety before connecting the limit switch(1) to an intrinsically safe circuit.
• M12 connector to EN 60947, 4-pole
43
1 2
1
1
4
3
30 Ω
2
30 Ω
M12
PROCESS
SERVICE

SensoGate WA131MH
20
3 Installation
3.1 Retractable Fitting: Installation
WARNING! Risk of explosion from mechanically generated sparks when used in explosive at-
mospheres. Take measures to prevent sparking. Follow the safety instructions.
➜Operation in Explosive Atmospheres, p. 8
Note: The possible installation angle is 10° above the horizontal plane. An installation angle of 360°
(i.e., upside down) is only permitted if using sensors approved for upside-down installation.
10°
10°
01. Check scope of delivery of the SensoGate WA131MH for completeness. ➜Package Contents, p. 10
02. Check the SensoGate WA131MH for damage.
03. Ensure the required sensor installation clearances. ➜Dimension Drawings, p. 48
04. Fasten the SensoGate WA131MH to the process port using the process connection.
05. Optional: If using the product in explosive atmospheres, connect the grounding connection of
SensoGate WA131MH to the plant’s equipotential bonding system.
See also
➜Operation in Explosive Atmospheres, p. 8
➜Commissioning, p. 22
3.2 Safety Accessories: Installation
Consult the related instructions for information on installing the safety accessories (e.g., ZU0818
retainer clamp).
See also
➜Safety Accessories, p. 7