WIKA GD-20 Series User manual

Operating instructions
Betriebsanleitung
Mode d'emploi
Manual de instrucciones
EN
DE
FR
ES
Gas density sensor, model GD-20
Gasdichtesensor, Typ GD-20
Capteur de densité de gaz, type GD-20
Sensor de densidad de gas, modelo GD-20
Examples/Beispiele/Exemples/Ejemplos

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WIKA operating instructions gas densitiy sensor, model GD-20
EN
DE
FR
ES
Operating instructions model GD-20 Page 3 - 32
Betriebsanleitung Typ GD-20 Seite 33 - 62
Mode d'emploi type GD-20 Page 63 - 94
Manual de instrucciones modelo GD-20 Página 95 - 125
Further languages can be found at www.wika.com.
© 09/2020 WIKA Alexander Wiegand SE & Co. KG
All rights reserved. / Alle Rechte vorbehalten.
WIKA®is a registered trademark in various countries.
WIKA®ist eine geschützte Marke in verschiedenen Ländern.
Prior to starting any work, read the operating instructions!
Keep for later use!
Vor Beginn aller Arbeiten Betriebsanleitung lesen!
Zum späteren Gebrauch aufbewahren!
Lire le mode d‘emploi avant de commencer toute opération !
A conserver pour une utilisation ultérieure !
¡Leer el manual de instrucciones antes de comenzar cualquier trabajo!
¡Guardar el manual para una eventual consulta!

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Contents
Contents
1. General information 5
2. Design and function 6
2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . 6
3. Safety 7
3.1 Explanation of symbols . . . . . . . . . . . . . . . . . . . . . 7
3.2 Intended use . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Improper use. . . . . . . . . . . . . . . . . . . . . . . . . 8
3.4 Personnel qualification . . . . . . . . . . . . . . . . . . . . . 8
3.5 Safety instructions for use in switchgear . . . . . . . . . . . . . . . 9
3.6 Labelling, safety marks . . . . . . . . . . . . . . . . . . . . . 10
4. Transport, packaging and storage 11
4.1 Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Packaging and storage . . . . . . . . . . . . . . . . . . . . . 11
5. Commissioning, operation 12
5.1 Mechanical mounting . . . . . . . . . . . . . . . . . . . . . . 12
5.1.1 Requirements for mounting point . . . . . . . . . . . . . . . . . 12
5.1.2 Installation using an adapter and measuring chambers . . . . . . . . . 12
5.1.3 Installing the instrument . . . . . . . . . . . . . . . . . . . . 13
5.2 Electrical mounting. . . . . . . . . . . . . . . . . . . . . . . 14
5.2.1 Connection assembly (model GD-20-D) . . . . . . . . . . . . . . 14
5.2.2 Pin assignment (model GD-20-D). . . . . . . . . . . . . . . . . 14
5.2.3 Requirements for shielding and grounding. . . . . . . . . . . . . . 14
5.2.4 RS-485. . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3 Modbus®. . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.4 Modbus®start-up kit . . . . . . . . . . . . . . . . . . . . . . 17
5.4.1 Establish connection to the computer . . . . . . . . . . . . . . . 17
5.4.2 Modbus®tool . . . . . . . . . . . . . . . . . . . . . . . 17
5.4.2.1 Factory settings . . . . . . . . . . . . . . . . . . . . . 18
5.4.2.2 Writing new parameters . . . . . . . . . . . . . . . . . . 18
5.4.2.3 Data logger . . . . . . . . . . . . . . . . . . . . . . . 19
5.4.2.4 Modbus®register and functional description . . . . . . . . . . . 19

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Contents
Declarations of conformity can be found online at www.wika.com
5.4.2.5 Data register, measured values . . . . . . . . . . . . . . . . 20
5.4.2.6 Configuration . . . . . . . . . . . . . . . . . . . . . . 21
5.4.2.7 Status register . . . . . . . . . . . . . . . . . . . . . . 23
5.5 Electrical mounting of model GD-20-A . . . . . . . . . . . . . . . . 24
5.5.1 Requirements for voltage supply . . . . . . . . . . . . . . . . . 24
5.5.2 Requirements for electrical connection . . . . . . . . . . . . . . . 24
5.5.3 Pin assignment (model GD-20-A). . . . . . . . . . . . . . . . . 24
5.5.4 Requirement for shielding and grounding . . . . . . . . . . . . . . 24
5.5.5 Connecting the instrument . . . . . . . . . . . . . . . . . . . 24
5.5.6 Testing the output signal for model GD-20-A, with field case. . . . . . . . 25
6. Faults 26
7. Maintenance and cleaning 26
7.1 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.2 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8. Dismounting, return and disposal 27
8.1 Dismounting . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.2 Return . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . 28
9. Specications 29

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1. General information
■The gas density sensor described in the operating instructions has been designed
and manufactured using state-of-the-art technology. All components are subject
to stringent quality and environmental criteria during production. Our management
systems are certified to ISO 9001 and ISO 14001.
■These operating instructions contain important information on handling the instru-
ment. Working safely requires that all safety instructions and work instructions are
observed.
■Observe the relevant local accident prevention regulations and general safety regula-
tions for the instrument's range of use.
■The operating instructions are part of the product and must be kept in the immediate
vicinity of the instrument and readily accessible to skilled personnel at any time. Pass
the operating instructions on to the next operator or owner of the instrument.
■Skilled personnel must have carefully read and understood the operating instructions
prior to beginning any work.
■The general terms and conditions contained in the sales documentation shall apply.
■Subject to technical modifications.
■Further information:
- Internet address: www.wika.de / www.wika.com
- Relevant data sheet: SP 60.77
- Application consultant: Tel.: [phone]
Fax: [phone]
[e-mail]
1. General information

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2. Design and function
2.1 Overview
Electrical connection (depending on version)
Case, product label
Spanner flats
Process connection, thread (depending on version)
2.2 Description
The described gas density sensors are equipped with sensors for pressure and tempe-
rature. From this, the integrated microprocessor electronics calculate the status parame-
ters for the gas density of the insulating gas used using algorithms.
2.3 Scope of delivery
■Gas density sensor
■Operating instructions
Cross-check scope of delivery with delivery note.




2. Design and function

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3. Safety
3.1 Explanation of symbols
WARNING!
... indicates a potentially dangerous situation that can result in serious
injury or death, if not avoided.
CAUTION!
... indicates a potentially dangerous situation that can result in light injuries
or damage to property or the environment, if not avoided.
Information
... points out useful tips, recommendations and information for efficient
and trouble-free operation.
3.2 Intended use
These gas density sensors are designed for use in plants filled with SF6gas and alterna-
tive insulating gases.There, the status variables pressure and temperature are measured
permanently. From this, the gas density sensor calculates the gas density value to assess
the plant status. It is possible to read out all the specified parameters via the RS-485 inter-
face in the Modbus®protocol (only model GD-20-D) or only the compensated pressure
value (p at 20 °C [68 °F]) by means of a 4 ... 20 mA current signal (only model GD-20-A).
The model GD-20 gas density sensors are therefore used for permanently monitoring the
stated status parameters in gas tanks.
The use of the GD-20 in dangerous process fluids (cf. pressure equipment directive fluid
group 1, see 2014/68/EU, article 13) is excluded. For a suitable product, please contact
the technical support (→ contact information at www.wika.com).
Only use the instrument in applications that lie within the technical performance limits.
The manufacturer or operator of the machine or plant in which the instrument is used
must ensure the compatibility of the wetted parts with the medium used.
The technical specifications contained in these operating instructions must be obser-
ved. Improper handling or operation of the instrument outside of its technical specifica-
tions requires the instrument to be taken out of service immediately and inspected by an
authorised WIKA service engineer.
The manufacturer shall not be liable for claims of any type based on operation contrary
to the intended use.
3. Safety

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3.3 Improper use
WARNING!
Injuries through improper use
Improper use of the instrument can lead to hazardous situations and
injuries.
▶Refrain from unauthorised modifications to the instrument.
▶Do not use the instrument within hazardous areas.
The operator must ensure the compatibility of the fluid with the materials used.
Any use beyond or different to the intended use is considered as improper use.
WARNING!
Physical injuries and damage to property and the environment
through exceeding the performance limits
Exceeding the performance limits can destroy the instrument and lead to
danger in the end-use application.
▶Use the instrument only in applications within the technical performance
limits (→ for performance limits, such as derating (maximum current
supply at a corresponding medium temperature), see chapter 9 “Specifi-
cations”).
▶Any permanent operation in the overload range is not permitted. Above
the highest permissible operating pressure, up to the overload limit, the
gas density sensor is operating outside its specification.The overload
range is intended to prevent damage to the gas density sensor, as part
of a pressure vessel system, during the pressure containment test.
▶The overload limit must never be exceeded, even when failures occur
in the end-use application. Loads above the overload limit can cause
irreversible damage, which can lead, for example, to permanent
measuring errors.
▶The manufacturer or operator of the machine or plant in which the
product is used must ensure the compatibility of the materials of the
wetted parts with the medium used.
▶The gas density sensor should not be used with abrasive or unstable
fluids, in particular not with hydrogen.
3.4 Personnel qualification
WARNING!
Risk of injury should qualification be insufficient
Improper handling can result in considerable injury and damage to property.
▶The activities described in these operating instructions may only be
carried out by skilled personnel who have the qualifications described
below.
3. Safety

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Skilled personnel
Skilled personnel, authorised by the operator, are understood to be personnel who,
based on their technical training, knowledge of measurement and control technolo-
gy and on their experience and knowledge of country-specific regulations, current
standards and directives, are capable of carrying out the work described and indepen-
dently recognising potential hazards.
Special operating conditions require further appropriate knowledge, e.g. of aggressive
media.
3.5 Safety instructions for use in switchgear
WARNING!
Residual media on the dismounted gas density sensor can result in
a risk to persons, the environment and equipment.
▶Take sufficient precautionary measures.
▶Aggressive media may be present should a failure occur.
The plant operator must ensure that the handling of SF6gas is only carried out by
a qualified company or by qualified persons who have been specially trained in
accordance with IEC 61634, section 4.3.1 or IEC 60480, section 10.3.1.
Installation and plant status which can lead to the formation of atomic hydrogen in the
connection channel of the transmitter must be completely avoided.
The maximum permissible pressures must be complied with.
Valid standards and guidelines for SF6gas
Installation, assembly, commissioning:
■BGI 753 (SF6plants and equipment in Germany)
■IEC 61634 (Handling of the SF6gas)
■IEC 60376 (New SF6gas, technical grade SF6gas)
■IEC 60480 (Used SF6gas)
■CIGRE report 276, 2005 (Practical SF6gas handling instructions)
Leaks during operation:
■IEC 60376 (New SF6gas, technical grade SF6gas)
■IEC 60480 (Used SF6gas)
■CIGRE 2002 (“SF6gas in the electrical industry”)
Repair work and maintenance:
■IEC 61634 (Use and handling of SF6gas in high-voltage switchgear and controlgear)
■CIGRE 1991 (Handling of SF₆ gas)
■CIGRE report 276, 2005 (Practical SF₆ gas handling instructions)
■CIGRE report 163, 2000 (Guide for SF₆ gas mixtures)
3. Safety

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SF₆ gas is a colourless and odourless, chemically neutral, inert and
non-flammable gas which is approx. five times heavier than air, non-toxic
and not harmful to the ozone layer. Detailed information is given in IEC
60376 and IEC 61634.
3.6 Labelling, safety marks
Product label (example)
Model
Measuring range compensated pressure
Density equivalent of the full scale of the compensated pressure
Pin assignment
Logos
Coded date of manufacture
Temperature range
Communication
Supply voltage
Gas mixture
P# article number
S# serial number
Before mounting and commissioning the instrument, ensure you read
the operating instructions!
GD-20-A
DE-63911 Klingenberg
Made in Germany







11
11
3. Safety

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4. Transport, packaging and storage
4.1 Transport
Check the gas density sensor for any damage that may have been caused by transport.
Obvious damage must be reported immediately.
CAUTION!
Damage through improper transport
With improper transport, a high level of damage to property can occur.
▶When unloading packed goods upon delivery as well as during inter-
nal transport, proceed carefully and observe the symbols on the
packaging.
▶With internal transport, observe the instructions in chapter 4.2
“Packaging and storage”.
4.2 Packaging and storage
WARNING!
Physical injuries and damage to property and the environment
caused by hazardous media
▶Before storing the instrument (following operation), remove any residual
media.This is of particular importance if the medium is hazardous to
health, e.g. caustic, toxic, carcinogenic, radioactive, etc.
Do not remove packaging until just before mounting.
Keep the packaging as it will provide optimum protection during transport (e.g. change
in installation site, sending for repair).
Permissible conditions at the place of storage:
■Storage temperature: -40 ... +70 °C [-40 ... +158 °F]
■Humidity: 95 % relative humidity (no condensation)
Avoid exposure to the following factors:
■Direct sunlight or proximity to hot objects
■Mechanical vibration, mechanical shock (putting it down hard)
■Soot, vapour, dust and corrosive gases
■Hazardous environments, flammable atmospheres
Store the gas density sensor in its original packaging in a location that fulfils the condi-
tions listed above. If the original packaging is not available, pack and store the instru-
ment as described below:
1. Wrap the instrument in an antistatic plastic film.
2. Place the instrument, along with the shock-absorbent material, in the packaging.
3. If stored for a prolonged period of time (more than 30 days), place a bag containing
a desiccant inside the packaging.
4. Transport, packaging and storage

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5. Commissioning, operation
WARNING!
Physical injury and/or damage to property due to the selection of
the wrong instrument version
▶Before installation, commissioning and operation, ensure that
the appropriate gas density sensor has been selected in terms of
measuring range, design and specific measuring conditions.
5.1 Mechanical mounting
Prior to commissioning, the gas density sensor must be subjected to a visual inspection.
■Leaking fluid is indicative of damage.
■Only use the gas density sensor if it is in perfect condition with respect to safety.
5.1.1 Requirements for mounting point
The mounting point must meet the following conditions:
■Sealing faces are clean and undamaged.
■Sufficient space for a safe electrical installation.
■Protected from weather influences. Permanent exposure to UV light/sunlight can lead
to a change in the colour of the plastic parts.
■Under corrosive environmental conditions (such as salty, humid air), reductions in
the gloss level of the metal surfaces, or even corrosion on the instrument, may occur,
which make readability of the product label more difficult.
■For information on tapped holes and welding sockets, see Technical information IN
00.14 at www.wika.com.
■Permissible ambient and medium temperatures remain within the performance
limits. Consider possible restrictions on the ambient temperature range caused
by mating connector used.
→ For performance limits see chapter 9 “Specifications”
The measuring location should preferably be positioned directly at the gas
compartment. The measurement at the end of measuring lines prevents
optimal results (unwanted temperature differences to the main tank).
5.1.2 Installation using an adapter and measuring chambers
CAUTION!
If model GD-20 is delivered with an adapter or measuring chamber, it
is completely mounted and tested for leak tightness in our company.
Dismounting compromises the leak tightness of the measuring assembly
and renders it unserviceable!
▶The process connections of the available adapters and/or measuring
chambers are to be properly sealed and connected to the measuring
location.
5. Commissioning, operation

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5.1.3 Installing the instrument
The max. torque depends on the mounting point and must be observed (e.g.
material and shape). If you have any questions, please contact our applica-
tion consultant.
→ For contact details see chapter 1 “General information” or the back page
of the operating instructions.
Spanner flats
1. Seal the sealing face (→ see “Sealing variants”).
2.At the mounting point, screw the gas density sensor in hand-tight.
3.Tighten with a torque spanner using the spanner flats.
Sealing variants
The sealing and instrument must be checked at regular intervals by the operator.
Spanner flats
Parallel threads
Seal the sealing face with flat gasket, lens-
type sealing ring or WIKA profile sealing.
per EN 837 per ISO 1179 (formerly 23852-E)


Tapered threads
Wrap threads with sealing material
(e.g. PTFE tape).
NPT, R and PT
5. Commissioning, operation

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5.2 Electrical mounting
WARNING!
The instrument shield does not act as a protective conductor for protection
of personnel, rather as a functional ground in order to shield the instru-
ment from electromagnetic fields.
5.2.1 Connection assembly (model GD-20-D)
■Use a cable consisting of shielded twisted pair data lines with suitable characteristics
for the particular operating conditions.
■Select a cable diameter that matches the cable bushing of the connector. Make sure
that the cable gland of the mounted plug has a tight fit and that the seals are present
and undamaged.Tighten the threaded connection and check that the seal is correct-
ly seated, in order to ensure the ingress protection.
■Make sure that no moisture enters at the cable end.
Installation example for model GD-20-D
5.2.2 Pin assignment (model GD-20-D)
Circular connector M12 x 1 (5-pin)
1 - -
2 U+Supply voltage
3 U-Mass
4 A Signal RS-485
5 B Signal RS-485
5.2.3 Requirements for shielding and grounding
■Only use shielded cables and connect the shield on one side to the read-out unit.
■The gas density sensor must be grounded via the process connection.
■Ensure that no earth circuits can occur.
End piece Y-connector 5 m cable
Sensors
Gateway
5. Commissioning, operation

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Electromagnetic interferences
Common mode interferences
Interferences in the common mode can be compensated by the cable shield or the earth
potential of the sensor.
T-connector Communication
module
Power
supply
Gateway
Sensor
Gas tank
5. Commissioning, operation

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Differential mode
Interferences in the differential mode can be compensated by a network of decoupling
capacitors that are located in front of the read-out unit.
5.2.4 RS-485
The physical layer for the Modbus®protocol is the serial RS-485 interface per EIA/
TIA-485.The differential signal between pins 4 and 5 (A and B) is evaluated with a
2-wire system (half-duplex).
5.3 Modbus®
The Modbus®communication protocol is based on a master/slave architecture.The
protocol implemented in the model GD-20 gas density sensor is Modbus®-RTU with
serial transmission via a 2-wire RS-485 interface.
T-connector
Sensor
Gas tank
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The Modbus®protocol is a single-master protocol.This master controls the entire data
transfer and monitors any possible timeouts (no reply from the addressed instrument).The
connected instruments may only send telegrams after request by means of the master.
Modbus®RTU (RTU: Remote Terminal Unit) transmits the data in binary form, guarante-
eing a good data throughput.
Detailed information on the protocol under www.Modbus.org
5.4 Modbus®start-up kit
The gas density sensor, with the optionally available start-up kit (order no. 14075896),
can be configured for operation at the measuring location.
A further function is an integrated data logger, showing measured data in a specific
cycle or writing it in a file.
The start-up kit consists of:
■Power supply unit
■Interface converter (RS-485 to USB)
■USB cable type A to type B
■Sensor cable with M12 x 1 connector
■Adapter cable for GDM-100-TI
■Modbus®tool
5.4.1 Establish connection to the computer
5.4.2 Modbus®tool
The software can be downloaded free of charge from the WIKA homepage: https://
de-de.wika.de/download_software_gas_density_sensors_de_de.WIKA
RS-485 USB
+
-
Interface converter
Voltage supply
5. Commissioning, operation

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After wiring and installing the software of the interface converter or copying the
Modbus®tool software, the program can be started.
System requirements
At least Microsoft®Windows®7 (32-bit)
Windows is a registered trademark of Microsoft Corporation in the United States and other countries.
5.4.2.1 Factory settings
The COM port allocated by the interface converter on the PC must be set for access
to the gas density sensor. Upon delivery, the address is set to 247 and the baud rate is
configured to customer specification.
With these settings, the gas density sensors can be read via the button “Read from
instrument”.
Configuration
■Tag number: WIKA
■Address: 247
■Baud rate: Customer-specific
■Parity: Customer-specific
5.4.2.2 Writing new parameters
Take note of the new communication parameters before writing them, as the parameters
will be required again for any new access to the gas density sensor.
Write the new values in the right fields (below the button “Write on instrument”).
Designation Valid values
Tag number 16 characters in ASCII code
Address 1 ... 247
Baud rate 1,200 ... 115,200
Parity None, even
By pressing the button “Write on instrument” the data in the fields is transmitted to the
instrument register. To finish the writing operation, interrupt the voltage supply of the gas
density sensor after the transmission before restoring it.
Afterwards, during the reading operation, the entered data becomes visible on the left-
hand side.
If Windows®is used with non-Latin character sets (e.g. Chinese), the area
settings of the system control must be changed to English (USA), since
otherwise, communication problems might occur.
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5.4.2.3 Data logger
The data logger is used for recording measured values over a certain time span.
After setting up COM ports, the baud rate and the min./max. address or interval, the
recording can be started. For continuous recording, it is possible to record the measured
data in the selected interval in a text file divided by tabs.
The recording is started with the green start symbol. Stop the recording using the red
stop symbol.
5.4.2.4 Modbus®register and functional description
The following documents (available under www.Modbus.org) are recommended for
understanding the Modbus®architecture which the following chapters will refer to.
■Modbus APPLICATION PROTOCOL SPECIFICATION
■Modbus over Serial Line Specification and Implementation Guide
The register structure is described in the following.
Communication via messages
General form of the messages
Instrument
address
Function Data CRC check
8 bit 8 bit n x 8 bit 16 bit
In accordance to Modbus®specification, separate messages must be divided by a
break of at least 3.5 characters.
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The characters within one message may not have spacing of more than 1.5 characters.
Examples of a typical transmission:
Intermission Message 1 ▶Intermission Message 2 ▶Intermission Message 3 ...
Valid function calls
Function Designation Description
03 Read holding registers Reading of one or more register values or the instru-
ment configuration
04 Read input register Reading a register value or the instrument configuration
06 Write single register Writing a register value or the instrument configuration
16 Write multiple registers Writing of one or more register values or the instrument
configuration
08 Diagnostic -
Sub code 00
Diagnostic function
23 Read/write multiple
registers configuration
Writing or reading of one/several register values or the
instrument configuration
5.4.2.5 Data register, measured values
Measured values can only be read and not written.
Model GD-20
Register Measurand Unit Based on
00000 Pressure (abs.) p bar Absolute pressure
00002 Pressure (abs.) p MPa Absolute pressure
00004 Pressure p Pa Absolute pressure
00006 Pressure p kPa Absolute pressure
00008 Pressure p psi Absolute pressure
00010 Pressure p N/cm² Absolute pressure
00012 Temperature T °C
00014 Temperature T K
00016 Temperature T °F
00018 Gas density rho g/l
00020 Gas density rho kg/m³
00022 Pressure standar-
dised to 20 °C [68 °F]
p20 bar Absolute pressure at 20 °C [68 °F]
5. Commissioning, operation