KROHNE DK37/M8 Wiring diagram

Variable area flowmeter
Equipment protection level (EPL) Gb and Db
in protection type intrinsic safety "i"
DK37/M8
DK37/M8DK37/M8
DK37/M8 Supplementary Instructions
Supplementary InstructionsSupplementary Instructions
Supplementary Instructions
© KROHNE 03/2019 - 4007510401 - AD DK37/M8 Exi INMETRO R01 en

CONTENTS
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DK37/M8
1 Safety instructions 3
1.1 General notes ................................................................................................................... 3
1.2 INMETRO approval ...........................................................................................................3
1.3 Approval according to the IECEx scheme ........................................................................ 3
1.4 Safety instructions............................................................................................................ 4
2 Device description 5
2.1 Device description ............................................................................................................ 5
2.2 Description code for type series DK37............................................................................. 5
2.3 Marking............................................................................................................................. 6
2.4 Flammable products ........................................................................................................ 7
2.5 Equipment category .........................................................................................................8
2.6 Types of protection ........................................................................................................... 9
2.7 Ambient temperature / temperature classes / product temperature .......................... 10
2.8 Surface temperature for equipment protection level Db .............................................. 12
2.9 Electrical data................................................................................................................. 12
3 Installation 13
3.1 Mounting ......................................................................................................................... 13
3.2 Special conditions........................................................................................................... 13
4 Electrical connections 14
4.1 General notes ................................................................................................................. 14
4.2 Power supply .................................................................................................................. 15
4.3 Inputs / Outputs .............................................................................................................. 15
4.4 Grounding and equipotential bonding............................................................................ 16
5 Operation 17
5.1 Start-up........................................................................................................................... 17
5.2 Operation ........................................................................................................................ 17
5.3 Electrostatic charge .......................................................................................................17
6 Service 18
6.1 Maintenance ................................................................................................................... 18
6.2 Dismantling .................................................................................................................... 18
7 Notes 19

SAFETY INSTRUCTIONS 1
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1.1 General notes
These additional instructions apply to explosion-protected versions of variable area flowmeter
with electrical built-ins with protection type intrinsic safety "i", equipment protection level
(EPL) Gb and Db.
They complete the standard manual for the non-explosion protected versions.
The information given in these instructions contains only the data relevant to explosion
protection.
The technical details given in the standard manual for the non-explosion protected versions
apply unchanged unless excluded or superseded by these supplementary instructions.
1.2 INMETRO approval
Conformity for use in hazardous areas with gas and dust was tested in accordance with the
"INMETRO Certification Scheme for Explosive Atmospheres" according to
ABNT NBR IEC 60079-0:2013 and ABNT NBR IEC 60079-11:2017.
Approval according to governmental regulation INMETRO no. 179/2010:
The "X" after the certificate number refers to special conditions for safe use of the device, which
have been listed in these instructions.
If needed, the INMETRO certificate can be downloaded from the manufacturer's website.
1.3 Approval according to the IECEx scheme
Conformity for use in hazardous areas with gas and dust was tested in accordance with the
"IECEx Certification Scheme for Explosive Atmospheres" according to
IEC 60079-0:2011, IEC 60079-15:2010 and IEC 60079-31:2013.
The number of the IECEx certificate is:
The "X" after the certificate number refers to special conditions for safe use of the device, which
have been listed in these instructions.
If needed, the IEC certificate can be downloaded from the manufacturer's website.
DNV 18.0135 X
DNV 18.0135 XDNV 18.0135 X
DNV 18.0135 X
IECEx KIWA 15.0020 X
IECEx KIWA 15.0020 XIECEx KIWA 15.0020 X
IECEx KIWA 15.0020 X

1 SAFETY INSTRUCTIONS
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1.4 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
explosion protection!
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.

DEVICE DESCRIPTION 2
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2.1 Device description
Variable area flowmeters measure and display the volume flow of flammable and non-
flammable gases and liquids.
2.2 Description code for type series DK37
The safety description code consists of the following elements *:
* positions which are not needed are omitted (no blank positions)
Figure 2-1: Available indicators
1 Indicator M8E.: one signal output 4...20 mA with a bargraph indicator
2 Indicator M8M.: up to two separately adjustable electrical limit switches
Figure 2-2: Safety description code
1 Type series of measuring unit DK
Type series of measuring unit DKType series of measuring unit DK
Type series of measuring unit DK
2 Type series of signal converter 37
Type series of signal converter 37Type series of signal converter 37
Type series of signal converter 37
3 Type series of indicators
Type series of indicatorsType series of indicators
Type series of indicators
M8M - mechanical indicator
M8E - electronic indicator
4 Design of indicator housing
Design of indicator housingDesign of indicator housing
Design of indicator housing
without - indicator housing in PPS
R - indicator housing in stainless steel
5 Optional differential pressure regulator
Optional differential pressure regulatorOptional differential pressure regulator
Optional differential pressure regulator
RE - inlet pressure regulator
RA - outlet pressure regulator
6 Limit switch (M8M version)
Limit switch (M8M version)Limit switch (M8M version)
Limit switch (M8M version)
K1 - one limit switch
K2 - two limit switches

2 DEVICE DESCRIPTION
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2.3 Marking
The marking of the entire device is clearly visible on the indication unit, in accordance with the
designation code.
Additional markings on the housing cover:
•SN - serial number
•SO - sales order / item
•PA - production order
•Vxxx - product configurator code
•AC - article code
Additional plate
The association of the housing cover to the device is confirmed by an additional plate with the
serial number on the interior of the indicator part.
Figure 2-3: Examples of the nameplates
1 Device designation
2 Manufacturer and manufacturer address
3 Manufacturing year
4 Rating data: temperature & pressure rating
5 PED data
6 Ex data according to notified body
7 Electrical connection data (depending on built-in equipment)
8 QR code
9 Safety instructions, disposal and data matrix

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.

2 DEVICE DESCRIPTION
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2.5 Equipment category
Variable area flowmeters are designed in accordance with the standards ABNT NBR IEC 60079-0
and ABNT NBR IEC 60079-11 in equipment protection level (EPL) Gb for use in zone 1.
Depending on the device version, variable area flowmeters are also designed in equipment
protection level (EPL) Db for use in zone 21.
The inside of the measuring unit is also approved for zone 1.
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.
Definition of zone 21:
An area in which an explosive atmosphere may occasionally occur in the form of a cloud of
flammable dust in the air under normal operation.

DEVICE DESCRIPTION 2
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2.6 Types of protection
The variable area flowmeter is designed with protection type intrinsic safety "i" according to
ABNT NBR IEC 60079-11.
The identification for equipment protection level (EPL) Gb is:
Ex ia IIC T6...T3 Gb
Ex ia IIC T6...T3 GbEx ia IIC T6...T3 Gb
Ex ia IIC T6...T3 Gb
The marking contains the following information:
The additional identification of the version for the equipment protection level (EPL) Db is:
Ex ia IIIC T75
Ex ia IIIC T75Ex ia IIIC T75
Ex ia IIIC T75°C...T200
C...T200C...T200
C...T200°C Db
C DbC Db
C Db
The marking contains the following information:
Ex ia
Ex iaEx ia
Ex ia Explosion protection through intrinsic safety, protection level "ia"
IIC
IICIIC
IIC Gas group, suitable for gas groups IIC, IIB and IIA
T6...T3
T6...T3T6...T3
T6...T3 Temperature class range, suitable for temperature classes T6...T1
Gb
GbGb
Gb EPL, suitable for zone 1 and zone 2
Table 2-1: Description of the marking
INFORMATION!
For the equipment protection level (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.
Ex ia
Ex iaEx ia
Ex ia Explosion protection through intrinsic safety, protection level "ia"
IIIC
IIICIIIC
IIIC Dust group, suitable for groups IIIC, IIIB and IIIA
T75
T75T75
T75°C...T200
C...T200C...T200
C...T200°C
CC
CMaximum surface temperature at +65°C / +149°F ambient temperature
Db
DbDb
Db EPL, suitable for zone 21 and zone 22
Table 2-2: Description of the marking
INFORMATION!
For the equipment protection level (EPL) Db, 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.

2 DEVICE DESCRIPTION
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2.7 Ambient temperature / temperature classes / product temperature
Due to the influence of the product temperature, variable area flowmeters with built-in electrical
equipment (electric variants) are not assigned to any fixed temperature class. The temperature
class of these devices is rather a function of the product temperature and ambient temperature
that is present and the specific device version.
The classification is shown in the following tables.
The tables take into account the following parameters:
•Built-in equipment
•Maximum values I
i
and P
i
for K1 and K2
•Ambient temperature T
amb
•Product temperature T
m
•Heat resistance of the connecting cable
When using more than one installed equipment, the data of the most unfavourable equipment
should be used.
For certain device versions, lower values apply due to differing boundary conditions (e.g. liner
materials). Here the user should consult the technical data sheet.
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 manufacturer's
installation instructions.
• It must be ensured that the flowmeter is not heated by the effects of additional heat radiation
(sunshine, neighbouring 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.

DEVICE DESCRIPTION 2
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The maximum product temperature is shown in the following tables.
Temperature
class
Ambient temperature
up to
Maximum permissible product temperature / maximum value
Type DK37/M8E/.. Type DK37/M8M/..K.
at 64 mW
Type DK37/M8M/..K.
at 169 mW
[°C] [°F] [°C] [°F] [°C] [°F] [°C] [°F]
T6 +40 +104 +70 +158 +85 +185 +40 +104
+50 +122 --+85 +185 - -
+60 +140 --+75 +167 - -
T5 +40 +104 +100 +212 +100 +212 +90 +194
+50 +122 +95 +203 +100 +212 +65 +149
+60 +140 +75 +167 +100 +212 - -
+65 +149 --+100 1+212 2- -
T4 +40 +104 +135 +275 +135 +275 +135 +275
+50 +122 +135 +275 +135 +275 +135 +275
+60 +140 +115 1+239 2+135 1+275 2+110 1+230 2
+65 +149 +100 1+212 2+135 1+275 2+100 1+212 2
T3 +40 +104 +160 +320 +200 1+392 2+160 +320
+50 +122 +140 +284 +190 1+374 2+135 +275
+60 +140 +115 1+239 2+150 1+302 2+110 1+230 2
+65 +149 +100 1+212 2+135 1+275 2+100 1+212 2
Table 2-3: Maximum permissible product temperature
1Temperature resistance of the cable ≥+80°C
2Temperature resistance of the cable ≥+176°F

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The permissible ambient temperature range is indicated on the nameplate; depending on the
device version it is
T
amb
= -40...+65°C / -40...+149°F or T
amb
= -25...+65°C / -13...+149°F.
The permissible minimum product temperature is -40°C/-40°F.
2.8 Surface temperature for equipment protection level Db
For use in areas with flammable dust it should be noted that the indicated maximum surface
temperature of T75°C at an ambient temperature of +65°C / +149°F and a product temperature
of +75°C / +167°F is valid without a dust coating.
For higher product temperatures the maximum surface temperature is defined by the product.
2.9 Electrical data
Built-in equipment for the variable area flowmeter may only be connected to separate
intrinsically safe circuits with the following maximum values:
Type Electrical built-ins Min. ambient temperature
DK37/M8E/../.. Signal output 4...20 mA -40°C/-40°F
DK37/M8M/../.. SC2-N0 -25°C/-13°F
DK37/M8M/../.. I7S2002-N
SJ2-SN -40°C/-40°F
DK37/M8M/../.. Without electrical built-ins -40°C/-40°F
Table 2-4: Minimum permissible ambient temperature depending on electrical built-ins
Maximum values
Device version U
i
[V] I
i
[mA] P
i
[mW] C
i
[nF] L
i
[μH]
DK37/M8E/../.. 30 120 1000 0~ 0
DK37/M8M/../..
SC2-N0... 16 25 64 165 150
52 169
DK37/M8M/../..
SJ2-SN 16 25 64 45 100
52 169
DK37/M8M/../..
I7S2002-N 16 25 64 165 120
52 169
Table 2-5: Maximum values for intrinsically safe circuits
WARNING!
Also, when operating the variable area flowmeter outside of the hazardous area, the connection
must be made to an intrinsically safe circuit.
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 by
qualified personnel trained in explosion protection. The information given in the manuals and the
supplementary instructions must be observed at all times.
Variable area flowmeters must be installed in such a way that
•there is no danger from mechanical impact effects.
•no external forces are affecting the indication unit.
•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.
3.2 Special conditions
Electrostatics
For painted versions, risks due to electrostatic charge must be minimized.
Observe additional information regarding electrostatics. For further information refer to
Electrostatic charge on page 17.
Thermal and electrical data
Observe the maximum ambient and product temperatures and electrical data.
For further information refer to
Ambient temperature / temperature classes / product
temperature
on page 10 and refer to Surface temperature for equipment protection level Db on
page 12 and refer to
Electrical data on page 12.
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.
DANGER!
Components made of titanium in oxygen applications
Components made of titanium in oxygen applicationsComponents made of titanium in oxygen applications
Components made of titanium in oxygen applications
Variable area flowmeters with titanium components are NOT
NOTNOT
NOT suitable for use in explosion-
protected areas in conjunction with oxygen applications (products with an oxygen content which
is significantly above the oxygen content in the earth's atmosphere)!

4 ELECTRICAL CONNECTIONS
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4.1 General notes
The built-in equipment is connected electrically in the indication unit. The circuits are designed
in protection type "intrinsically safe" and galvanically isolated from ground (test voltage
≥500 V
eff
).
The connecting cables should be selected according to the applicable installation standards and
the maximum operating temperature.
Ensure that no residual current can form between separate intrinsically safe signal circuits.
•The connecting cables must be fixed and laid so they are sufficiently protected against
damage.
•Not used cores must be securely connected to the earth potential of the hazardous area or
carefully insulated against each other and against earth (test voltage ≥500 V
eff
).
•Lay cables so as to ensure that there is sufficient distance between surfaces of the
measuring unit and the connecting cable.
•If the blind plugs / cable entries supplied separately on customer request, the influence of
the components on the IP protection class of the housing or the thermal data must be
validated.
Recommendation:
IP protection class: ≥IP66/67 according to IEC 60529
Temperature range: -40...+80°C / -40...+176°F
•The outer diameter of the connecting cable must be within the sealing range of the cable
entry (plastic PG 3...7 mm / 0.12...0.28", metal PG 6...10 mm / 0.24...0.39").
•Unused cable entries are to be closed (>IP66/67).
Ensure that the gaskets and incised gasket ring are tight.

ELECTRICAL CONNECTIONS 4
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Connection diagrams
4.2 Power supply
The variable area flowmeter does not require a separate power supply. The necessary power for
the built-in electrical equipment is supplied via the signal circuits.
4.3 Inputs / Outputs
The terminal assignment of the built-in electrical equipment is described in the product
documentation. The signal circuits of the variable area flowmeters may only be connected to
certified intrinsically safe slave units or circuits. For more information refer to chapter
"Electrical data".
Figure 4-1: Connection diagram for indicator M8M - M8MG
1 Connection Kmin
2 Connection Kmax
Figure 4-2: Connection diagram for indicator M8E - M8EG
1 Connection signal output 4...20 mA

4 ELECTRICAL CONNECTIONS
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4.4 Grounding and equipotential bonding
If the device is not sufficiently electrostatically grounded via the process pipes, an additional
ground connection must be established using the ground terminal 1. The position of the ground
terminal is illustrated below. The connection only ensures an electrostatic connection of the
device and does not comply with the requirements of an equipotential bonding connection.
Any existing cable shields and all cores that are not used must be carefully insulated against
each other and against ground (test voltage ≥500 V
eff
) according to applicable installation
regulations.
Figure 4-3: Position of the ground terminal

OPERATION 5
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5.1 Start-up
Start-up is only permitted when the variable area flowmeter:
•is correctly installed in the system and connected.
•has been checked for the proper state with regard to its installation and connection
requirements.
•has been properly sealed in the electronic compartment or there is no explosive atmosphere
present.
The user of the system must have it checked before start-up in compliance with the national
regulations for checks before startup.
5.2 Operation
Variable area flowmeters must be operated in such a way that they remain within the maximum
and minimum permissible temperatures and pressures and the electrical limit values.
Variable area flowmeters may only be operated if the equipment parts necessary for safety are
effective in the long run, and are not rendered inoperable during operation.
Adjusting the limit switch and operating the display during operation is permitted. To do so,
remove the housing cover. Close the housing cover immediately after the adjustment of the limit
switches or the operation of the display.
For more information refer to chapter "Dismantling".
5.3 Electrostatic charge
In order to avoid ignition hazards due to electrostatic charge, painted versions of the
variable area flowmeter DK37 M8. R.... may not be used in areas where the following
appear:
•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.
WARNING!
Ignition risks caused by pressure surges, impact or friction must particularly be avoided when
titanium measuring units are used.
INFORMATION!
Versions with plastic housing are equipped with an electrostatically conductive plastic.
CAUTION!
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 tests 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.
•Checking the piping connections and the measuring unit as well as the needle valve, if
necessary, for leakage.
•Include the flowmeter in the regular pressure testing of the process line.
The cover is to be closed following maintenance work on the indicator.
6.2 Dismantling
Replacing the display
Replacing the displayReplacing the display
Replacing the display
Due to the modular design of the variable area flowmeters, from a safety perspective the
complete display can be replaced with identical spare parts.
Exchanging the entire device
Exchanging the entire deviceExchanging the entire device
Exchanging the entire device
The dismantling and installation is within the responsibility of the operator.
Exchanging and dismantling should take place in a de-energised state, if at all possible. If this is
not possible, the basic conditions for intrinsic safety (e.g. no grounding or connection of different
intrinsically safe circuits to one another) must be observed during dismantling.
CAUTION!
There may be a loss of measuring accuracy!
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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47058 Duisburg (Germany)
Tel.: [phone]
Fax: [phone]
[email protected]
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