KROHNE GA24 Wiring diagram

Variable area flowmeter
Equipment protection level Gb
in protection type intrinsic safety "i"
GA24
GA24GA24
GA24 Supplementary Instructions
Supplementary InstructionsSupplementary Instructions
Supplementary Instructions
© KROHNE 10/2020 - 4000836703 - AD GA24 Exia Gb R04 en

CONTENTS
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GA24
1 Safety instructions 3
1.1 General notes ................................................................................................................... 3
1.2 EC conformity ................................................................................................................... 3
1.3 Safety instructions............................................................................................................ 3
2 Device description 4
2.1 Device description ............................................................................................................ 4
2.2 Safety description code ....................................................................................................4
2.3 Marking............................................................................................................................. 5
2.4 Flammable products ........................................................................................................ 7
2.5 Equipment category .........................................................................................................8
2.6 Types of protection ........................................................................................................... 8
2.7 Ambient temperature / temperature classes.................................................................. 9
2.8 Electrical data................................................................................................................. 10
3 Installation 11
3.1 Mounting ......................................................................................................................... 11
3.2 Special conditions........................................................................................................... 12
4 Electrical connections 13
4.1 General notes ................................................................................................................. 13
4.2 Grounding and equipotential bonding............................................................................ 13
5 Operation 14
5.1 Start-up........................................................................................................................... 14
5.2 Operation ........................................................................................................................ 14
5.3 Electrostatic charge .......................................................................................................14
6 Service 16
6.1 Maintenance ................................................................................................................... 16
6.2 Dismantling .................................................................................................................... 16
7 Notes 17

SAFETY INSTRUCTIONS 1
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1.1 General notes
This additional instruction applies to explosion-protected versions of variable area flowmeter
with electrical built-ins with protection type intrinsic safety "i", equipment protection level (EPL)
Gb.
It completes the standard manual for the non explosion-protected versions.
The information given in this instruction contains only the data relevant to explosion protection.
The technical details given in the manual for the non explosion-protected versions remain
unchanged unless they will be excluded or replaced by this supplementary instruction.
1.2 EC conformity
The manufacturer declares with the EU declaration of conformity on his own responsibility
conformity with the protection goals of directive 2014/34/EU for use in hazardous areas with gas.
The EU type examination certificate of the Physikalisch Technische Bundesanstalt (PTB) forms
the basis of the EU declaration of conformity. Conformity with harmonised standards was
checked in accordance with EN IEC 60079-0:2018 and EN 60079-11:2012.
The "X" after the certificate number refers to special conditions for safe use of the device, which
have been listed in these instructions.
If necessary, the EU type examination certificate can be downloaded from the manufacturer's
website.
1.3 Safety instructions
If these instructions are not followed, there is a risk of explosion.
Assembly, installation, start-up and maintenance may only be performed by personnel trained in
personnel trained inpersonnel trained in
personnel trained in
explosion protection
explosion protectionexplosion protection
explosion protection!
PTB 05 ATEX 2025 X
PTB 05 ATEX 2025 XPTB 05 ATEX 2025 X
PTB 05 ATEX 2025 X
CAUTION!
The operator or his agent is responsible for observing any additional standards, directives or
laws if required due to operating conditions or place of installation.
This applies in particular to the use of easily detachable process connections when measuring
flammable media.
CAUTION!
When an equipment fault is detected the device shall be de-energised and send back to the
manufacturer for repair.

2 DEVICE DESCRIPTION
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2.1 Device description
Variable area flowmeters measure and display the flow of flammable and non-flammable gases
and liquids. Up to two separately adjustable electrical limit switches can be mounted to the local
indication.
2.2 Safety description code
The safety description code consists of the following elements*:
* positions which are not needed are omitted (no blank positions)
Figure 2-1: Safety description code GA24
1 Material of connection
Material of connectionMaterial of connection
Material of connection
R - stainless steel
PTFE - stainless steel with PTFE
2 Limit switches / signal output
Limit switches / signal outputLimit switches / signal output
Limit switches / signal output
K1 - one limit switch
K2 - two limit switches
Figure 2-2: Safety description code TG21
1 TG - immersion limit switch
2 21 - version 21
Figure 2-3: Safety description code MS14
1 MS - Magnetic switch
MS - Magnetic switchMS - Magnetic switch
MS - Magnetic switch
2 14 - Reed cartridge 14
14 - Reed cartridge 1414 - Reed cartridge 14
14 - Reed cartridge 14
3 Limit switch
Limit switchLimit switch
Limit switch
without - limit switch with cable tail
A - limit switch with connection box (standard)

DEVICE DESCRIPTION 2
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2.3 Marking
The marking of the entire device is on the indication unit, where the following identification plate
can be found.
Figure 2-4: Example of a nameplate
1 Device type
2 Manufacturer
3 Disposal symbol
4 Identification number of the notified body ATEX & PED
5 Note to observe the documentation, China RoHs and data matrix code
6 Marking according to the notified body
7 Serial number
8 Year of manufacture
9 PED data
Figure 2-5: Example of marking of limit switch TG21
1 Device type
2 Manufacturer
3 Electrical connection data
4 Built-in equipment
5 Note to observe the documentation, disposal and China RoHs

2 DEVICE DESCRIPTION
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No Ex marking for MS14 and MS14/A, because the Reed limit switch operates as a simple device
and complies to intrinsic safety EN 60079-11, paragraph 5.7.
Figure 2-6: Example of a nameplate for the limit switch MS14
1 Device type
2 Manufacturer
3 Ambient temperature
4 Internet site
5 Electrical connection data
6 Note to observe the documentation
Figure 2-7: Example of a nameplate for the limit switch MS14/A
1 Device type
2 Manufacturer
3 Ambient temperature
4 Internet site
5 Electrical connection data
6 Note to observe the documentation

DEVICE DESCRIPTION 2
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2.4 Flammable products
Atmospheric conditions:
Atmospheric conditions:Atmospheric conditions:
Atmospheric conditions:
The standard atmospheric conditions under which it may be assumed that Ex equipment can be
operated are:
•Temperature: -20...+60°C / -4...+140°F
•Pressure: 80...110 kPa (0.8...1.1 bar) / 11.6...15.9 psi
•Air with normal oxygen content, typically 21%v/v
Ex equipment operating outside the standard temperature range must be tested and certified
(e.g. for ambient temperature range -40...+65°C / -40...+149°F).
Ex equipment operating outside the standard atmospheric pressure range and standard oxygen
content is not permitted.
Operating conditions:
Operating conditions:Operating conditions:
Operating conditions:
The measuring unit of variable area flowmeters operate outside the standard atmospheric
pressure range, which means that explosion protection, regardless of the zone assignment, is
fundamentally not applicable for the measuring unit (piping).
WARNING!
Operation with flammable products is only permitted as long as no explosive fuel/air mixture
builds up inside of the piping at the same time the atmospheric conditions are exceeded.
The operator is responsible to ensure that the flowmeter is operated safely in terms of the
temperature and pressure of the products used. In case of operation with flammable products
the measuring units must be included in the periodic pressure tests of the piping.
For additional information regarding electrostatics to be observed refer to Electrostatic charge
on page 14
.

2 DEVICE DESCRIPTION
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2.5 Equipment category
Variable area flowmeters are designed according to EN 60079-0 and EN 60079-11 in
equipment protection level (EPL) Gb for use in zone 1. The inside of the measuring unit is also
approved for zone 1.
2.6 Types of protection
The variable area flowmeter is designed in type of protection "intrinsic safety", protection level
"ia" according to EN 60079-11.
The marking is: II 2G Ex ia IIC T6...T1 Gb
II 2G Ex ia IIC T6...T1 GbII 2G Ex ia IIC T6...T1 Gb
II 2G Ex ia IIC T6...T1 Gb
The marking contains the following information:
INFORMATION!
Definition of zone 1:
An area in which an explosive atmosphere, as a result of the mixture of flammable substances in
the form of gas, steam or mist with air, under normal operation may occasionally occur.
II
IIII
II Explosion protection, group II
2
22
2Equipment category 2
G
GG
GGas explosion protection
ia
iaia
ia Intrinsically safe, level of protection "ia"
IIC
IICIIC
IIC Suitable for gas groups IIC, IIB and IIA
T6...T1
T6...T1T6...T1
T6...T1 Temperature class range, suitable for temperature classes T6...T1
Gb
GbGb
Gb EPL, suitable for zone 1 or zone 2
Table 2-1: Description of the marking
INFORMATION!
The temperature class of the device depends on the product temperature.
INFORMATION!
For the equipment category II 2 G or EPL Gb, connection to an intrinsically safe circuit with
protection level "ib" is required.
When connecting the variable area flowmeter to an intrinsically safe circuit with protection level
"ia", a higher protection level is given.

DEVICE DESCRIPTION 2
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2.7 Ambient temperature / temperature classes
Due to the influence of the product temperature, no fixed temperature class is assigned to
variable area flowmeters. The temperature class of these devices is rather a function of the
present product temperature and ambient temperature. There is no distinction between devices
with one or two contacts. The classification is outlined in the following tables.
The tables take into account the following parameters:
•Maximum values P
i
•Ambient temperature T
amb.
•Product temperature T
m
•Limit switch TG21 or MS14
Maximum permissible product and ambient temperatures for TG21
Maximum permissible product and ambient temperatures for MS14/.
The maximum product and ambient temperature is +85°C / +185°F.
These values may be limited by the information contained in the standard manual.
The maximum values listed in the manual must be taken into consideration.
Minimum product temperature for all versions
The minimum product temperature is -20°C/-4°F.
INFORMATION!
The maximum permissible product temperatures listed in the tables are valid under
the following conditions:
• The measuring device is installed and operated in accordance with the installation
instructions in the standard manual.
• It must be ensured that the flowmeter is not heated by the effects of additional heat radiation
(sunshine, neighboring system components) and thus operated above the permissible
ambient temperature range.
• Insulation must be limited to the piping.
Unobstructed ventilation of the indicator part must be ensured.
Supply Type 1 [ ≤34mW] Type 2 [ ≤64mW] Type 3 [ ≤169mW]
Temperature class T6 T5 T4...T1 T6 T5 T4...T1 T6 T5 T4...T1
Max. product temperature
[°C] 70 85 95 60 75 95 35 50 70
Max. product temperature
[°F] 158 185 203 140 167 203 95 122 158
Table 2-2: Max. permissible product and ambient temperatures TG21

2 DEVICE DESCRIPTION
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2.8 Electrical data
Limit switch TG21
The built-in intrinsically safe NAMUR limit switch TG21 may only be connected to isolation
switching amplifiers with separated intrinsically safe circuits to EN 60947-5-6 with the following
max. values:
When connecting to intrinsically safe circuits, take into consideration the following maximum
values per circuit for the energy stores.
Limit switch MS14
Built-in limit switch MS14 may only be connected to separate intrinsically safe circuits with the
following maximum values:
When connecting to intrinsically safe circuits, take into consideration the following maximum
values per circuit for the energy stores.
Supply P
i
[mW] U
i
[V] I
i
[mA]
Type 1 34 16 25
Type 2 64 16 25
Type 3 169 16 52
Table 2-3: Maximum values of the power supply units
C
i
[nF] L
i
[µH]
165 150
Table 2-4: Maximum values per circuit
P
i
[W] U
i
[V] I
i
[mA]
130 100
Table 2-5: Maximum values of the power supply units
C
i
[nF] L
i
[µH]
0 0
Table 2-6: Maximum values per circuit
WARNING!
Also, when operating the variable area flowmeter outside of the hazardous area, the connection
must be made to intrinsically safe circuits.
When connecting to non-intrinsically safe circuits, there is a risk of damage to the safety-
defining components.

INSTALLATION 3
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3.1 Mounting
Mounting and setup must be carried out according to the applicable installation standards
(e.g. IEC 60079-14) by qualified personnel trained in explosion protection.
The information given in the manual and the supplementary instructions must always be
observed.
Variable area flowmeters must be installed in such a way that
•there is no danger from mechanical impact effects.
•there are no external forces affecting the indicator part.
•the device is accessible for any necessary visual inspections and can be viewed from all sides.
•the nameplate is clearly visible.
•it can be operated from a location with secure footing.
CAUTION!
The manufacturer is not liable for any damage resulting from improper use or use other than the
intended purpose. This applies in particular to hazards due to insufficient corrosion resistance
and suitability of the materials in contact with product.
WARNING!
Mounting of limit switches
Mounting of limit switchesMounting of limit switches
Mounting of limit switches
Mounting the limit switches ensures the electrostatic connection to the indicator. Make sure that
they are properly mounted and that the mounting elements fit properly.

3 INSTALLATION
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3.2 Special conditions
Equipotential bonding
The variable area flowmeters type GA24/.... /K. must be connected to the equipotential bonding
system of the hazardous area.
For further information refer to
Grounding and equipotential bonding on page 13.
Flammable products
In case of operation with flammable products the measuring units must be included in the
periodic tests of the pipelines and fittings.
Electrostatics
Observe additional information regarding electrostatics.
For further information refer to
Electrostatic charge on page 14.
Thermal data
Observe the maximum ambient and product temperatures.
For further information refer to
Ambient temperature / temperature classes on page 9.
DANGER!
Operation with flammable products outside of atmospheric conditions (-20
° C ≤T ≤+60 ° C and
0.8 bar ≤P ≤1.1 bar) is only permissible if no explosive product/air mixture is formed inside of
the flowmeter.
The operator is responsible to ensure that the measuring system is operated safely in terms of
the temperature and pressure of the media used.

ELECTRICAL CONNECTIONS 4
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4.1 General notes
The separate intrinsically safe signal circuits of protection level "ia" or "ib" are electrically
connected in the terminal compartment of the plug housing for the limit switch type TG21 and
MS14. The limit switch MS14 is connected to the strandes wires. The terminal housing must have
a protection class of min. IP20. Take note of the polarities given for the limit switch TG21.
Connecting cable
Connecting cableConnecting cable
Connecting cable
The connecting cables must be selected according to prevailing installation standards
(e.g. EN 60079-14). The outer diameter of the connecting cables must be within the sealing
range of the cable entry. The connecting cables must be fixed and laid so they are sufficiently
protected against damage.
All cores that are not used must be carefully insulated against each other and against ground
(test voltage ≥500 V
eff
).
4.2 Grounding and equipotential bonding
If the device is not sufficiently electrostatically grounded via the process pipes, an additional
ground connection 1must be established using the ground terminal. The location of the ground
connection 1on the back of the housing is shown below. This connection only ensures
electrostatic grounding of the device and does not meet the requirements for equipotential
bonding.
The conductive parts of the limit switches are connected to the variable area flowmeter housing.
Ensure proper mounting and fit of the mounting elements.
Figure 4-1: Grounding and equipotential bonding
1 Grounding connection

5 OPERATION
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5.1 Start-up
Make the following checks before starting up the device:
•Suitability of the materials used for the measuring unit and for the gaskets for adequate
resistance to corrosion from the product.
•Correct connection of the built-in electrical equipment for the electrical variant.
•Fit of the mounting elements of the limit switches.
•Electrostatic grounding of the device.
5.2 Operation
Adjusting the limit switch during operation is permitted.
To do this, loosen the fastening screws on the mounting device.
Tighten the fastening screws again immediately after the switching point on the limit switch has
been set.
Additionally the switching behaviour of the limit switch TG21 is to adjust in its terminal box.
Close the terminal compartment immediately after adjustment.
The switching function of the MS14/. is determined by the fitting position of the Reed contact
cartridge. A changing of the position during operation is permitted. Close the limit switch
housing immediately afterwards.
5.3 Electrostatic charge
In order to avoid ignition hazards due to electrostatic charge, variable area flowmeters
may not be used in areas with:
•processes that generate strong charges,
•mechanical friction and cutting processes,
•spraying of electrons (e.g. in the vicinity of electrostatic painting systems) or
•pneumatically conveyed dust is exposed.
To minimise danger due to electrostatic discharge, the variable area flowmeters type
GA24/./ .. /K/ may not be used in areas in which there are processes that generate strong
charges.
In variable area flowmeters, it is possible under field conditions for charge separation to occur in
the measuring tube due to the transport of non-conductive fluids and/or when the flow comes
into contact with non-conductive built-ins.
In glass devices, it is basically possible for the electrostatic field generated inside the measuring
tube to "punch through" to the outside of the device. For that reason, variable area flowmeters
need to be permanently grounded by the operator via the process connections in order to allow
discharge of electrostatic charge.
The operator is also responsible for continuing the complete grounding of the process line.
CAUTION!
Ignition risks caused by pressure surges, impact or friction must be avoided for floats.

OPERATION 5
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If grounding cannot be made via the process connections, e.g. top and bottom connection blocks
are made of plastic, the flowmeter should be connected to the local ground potential via the
connection to ground described in the section "Grounding and equipotential bonding".
This connection only ensures electrostatic grounding of the device and does not meet the
requirements for equipotential bonding.
When dust-free gases or liquids are measured, the flow rate should not exceed 10 times the
nominal flow rate. The max. allowable operating pressure PS printed on the nameplate is to be
considered.
WARNING!
Electrostatic charging of the housing surface by friction must be avoided. The devices must not
be dry cleaned.

6 SERVICE
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6.1 Maintenance
Maintenance work of a safety-relevant nature within the meaning of explosion protection may
only be carried out by the manufacturer, his authorised representative or under the supervision
of authorised inspectors.
For systems in hazardous areas, regular checks are required in order to maintain the proper
condition.
The following checks are recommended:
•Check the housing, the cable entries and the feed lines for corrosion and/or damage.
•Check the measuring unit and the piping connections for leakage of the glass cone.
•Check the measuring unit and the indicator for dust deposits.
•Include the flowmeter in the periodic pressure test of the process line.
6.2 Dismantling
Electrical connection
Dismantling should take place in a de-energised state, if at all possible. If that is not possible,
the basic conditions for intrinsic safety (e.g. no grounding or connection of different intrinsically
safe circuits) must be observed during dismantling.
CAUTION!
• Pressurised pipes have to be depressurised before removing the measuring unit.
• In the case of environmentally critical or hazardous products, appropriate safety precautions
must be taken with regard to residual liquids in the measuring unit.
• New gaskets have to be used when re-installing the device in the piping.

NOTES 7
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7 NOTES
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NOTES 7
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KROHNE –Products, Solutions and Services
• Process instrumentation for flow, level, temperature, pressure measurement
and process analytics
• Flow metering, monitoring, wireless and remote metering solutions
• Engineering, commissioning, calibration, maintenance and training services
Head Office KROHNE Messtechnik GmbH
Ludwig-Krohne-Str. 5
47058 Duisburg (Germany)
Tel.: [phone]
Fax: [phone]
[email protected]
© KROHNE 10/2020 - 4000836703 - AD GA24 Exia Gb R04 en - Subject to change without notice.
The current list of all KROHNE contacts and addresses can be found at:
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