KROHNE DK32 Series Wiring diagram

Variable area flowmeters
without electrical built-ins
Type series DK32, DK34, DK37 M8M, DK37 M8MR, H250 M8MG, H250 M8MGR,
H250 M40, H250 M40R, DK46, DK47, DK48, DK800, GA24, VA40
Equipment category II 2G, II 2D
VA FLOWMETERS Supplementary Instructions
© KROHNE 09/2022 - 4000419908 - AD VA Mech Ex Gb-Db R08 en

CONTENTS
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VA FLOWMETERS
1 Safety instructions 3
1.1 General notes ................................................................................................................... 3
1.2 EU conformity ................................................................................................................... 3
1.3 UK conformity................................................................................................................... 3
1.4 Safety instructions............................................................................................................ 4
2 Device description 5
2.1 Device description ............................................................................................................ 5
2.2 Designation code .............................................................................................................. 5
2.3 Marking............................................................................................................................. 8
2.4 Flammable products ...................................................................................................... 11
2.5 Equipment category ....................................................................................................... 12
2.6 Types of protection ......................................................................................................... 12
2.7 Ambient temperature / Product temperature ............................................................... 13
2.8 Surface temperature...................................................................................................... 15
2.9 Ignition hazard assessment / protective measures ...................................................... 16
3 Installation 17
3.1 Mounting......................................................................................................................... 17
3.2 Special conditions........................................................................................................... 17
3.3 Grounding and equipotential bonding............................................................................ 18
4 Operation 21
4.1 Start-up........................................................................................................................... 21
4.2 Operation ........................................................................................................................ 21
4.3 Static electricity.............................................................................................................. 21
4.3.1 Electrostatic charge caused by ambient conditions ............................................................ 21
4.3.2 Charging non-conductive external parts by cleaning .......................................................... 22
4.3.3 Process dependent charging................................................................................................ 22
5 Service 23
5.1 Dismantling .................................................................................................................... 23
5.2 Maintenance ................................................................................................................... 23
6 Notes 25

SAFETY INSTRUCTIONS 1
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1.1 General notes
These additional instructions apply to explosion-protected versions of variable area flowmeters
with protection type "design safety c", category II 2G, category II 2D.
They complete the standard documentation 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 manual for the non explosion-protected versions remain
unchanged unless they will be excluded or replaced by this supplementary instruction.
1.2 EU conformity
The manufacturer declares with the EU declaration of conformity on his own responsibility
conformity with the requirements of directive 2014/34/EU for use in hazardous areas with gas
and dust.
Conformity with the regulations was checked by the manufacturer in accordance with
ISO 80079-36:2016 und ISO 80079-37:2016.
Third party certification is not required in accordance with the conformity assessment procedure
for non-electrical equipment group II according item 13, section 1b (ii) of the directive
2014/34/EU (ATEX).
The technical documentation has been stored at the Physikalisch- Technische Bundesanstalt
(PTB), Braunschweig, Germany under the registration number:
The "X" after the registration number refers to special conditions for safe use of the device,
which have been listed in these instructions.
1.3 UK conformity
The manufacturer declares with the UK declaration of conformity on his own responsibility
conformity with the requirements of UKSI 2016:1107 (as amended by UKSI 2019:696 –
Schedule 3A, Part 6) for use in hazardous areas with gas and dust.
Conformity with the regulations was checked by the manufacturer in accordance with
ISO 80079-36:2016 und ISO 80079-37:2016.
Third party certification is not required in accordance with the conformity assessment procedure
for non-electrical equipment group II according amendment to regulation 39.
PTB 03 ATEX D127 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 flow of flammable and non-flammable gases
and liquids.
2.2 Designation code
The safety designation code consists of the following elements *:
Figure 2-1: Safety designation code for the type series of DK32 / DK34
1 Type series of measuring unit DK
32 - with valve and horizontal connection
34 - without valve and vertical connection
2 Optional flow regulator
RE - for variable inlet pressure
RA - for variable outlet pressure
3 High-temperature version
HT - high-temperature version
4 Version
Ex - explosion-protected equipment
Figure 2-2: Safety designation code for the type series of DK37/M8M
1 Type series of DK37, optional with needle valve
2 Type series of M8M, mechanical indicator
3 Design of indicator housing
without - indicator housing in PPS
R - indicator housing in stainless steel
4 Optional flow regulator
RE - for variable inlet pressure
RA - for variable outlet pressure

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Figure 2-3: Safety designation code for the type series of H250/M8MG
1 Type series of measuring unit H250
2 Materials / versions
RR - stainless steel
C - PTFE or PTFE with ceramic liner
HC - Hastelloy®
Ti - Titanium
MO - Monel
IN - Inconel
F - Food
3 Type series of indicators - M8
4 Design of indicator M8
MG - mechanical indicator
5 Design of indicator housing
without - indicator housing in PPS
R - indicator housing in stainless steel
6 Version
Ex - explosion-protected version
Figure 2-4: Safety description code for the type series of H250 M40
1 Type series of measuring unit H250
H250 - standard version, vertical upwards
H250H - horizontal orientation
H250U - vertical downwards
2 Measuring unit materials / versions
RR - stainless steel
C - PTFE or PTFE/ceramics
HC - Hastelloy® C
Ti - Titanium
MO - Monel
IN - Inconel
F - Food
3 Heating jacket version
blank - without heating jacket
B - with heating jacket
4 Signal converter version
M40 - aluminium housing, painted (standard)
M40R - stainless steel housing
5 High-temperature version
blank - without HT extension
HT - with HT extension
6 Version
Ex - explosion-protected version

DEVICE DESCRIPTION 2
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* positions which are not needed are omitted (no blank positions)
Figure 2-5: Safety designation code for the type series of DK glass
1 R - with integrated inlet pressure regulator (DKR46 only)
2 Device type
46 - Overall length of measuring cone 65 mm / 2.6"
47 - Overall length of measuring cone 150 mm / 5.9"
48 - Overall length of measuring cone 300 mm / 11.8"
800 - Overall length of measuring cone 100 mm / 3.9"
3 Material for top and bottom fittings
N - brass
R - stainless steel
PV - PVDF
4 Flow regulator
RE - flow regulator for variable inlet pressure
RA - flow regulator for variable outlet pressure
Figure 2-6: Safety designation code GA24
1 Material of connection
R - stainless steel
PTFE - stainless steel with PTFE
Figure 2-7: Safety designation code VA40
1 Connection type
V - screw connection
S - tube socket
F - flange connection
A - aseptic connection, conforming to food standards
2 Material of connection
R - stainless steel 1.4404 (316 L)
ST - steel, electroplated and chromised
PV - plastic PVDF

2 DEVICE DESCRIPTION
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2.3 Marking
The flowmeters are identified by the following nameplates (examples are not to scale):
Nameplate DK32, DK34, DK32 .. HT, DK34 .. HT
Figure 2-8: Example of a nameplate for DK32 HT (ATEX)
Nameplate DK32, DK34, DK32 .. HT, DK34 .. HT
Figure 2-9: Example of a nameplate for DK32 HT (UKCA)
DK32 ... HT
P/A: 123456789.001
S/N: D################
TS: 200°C
PS: ... bar Ptmax: ... bar
PED/G1/4.3/SEP
Luft / air
0.0181 mPa s 1.013 bar abs.
1.293 kg/Nm3
20°CTag-No: ###################
Reg.No.PTB03ATEXD127X
II2G Ex h IIC T6...T3 Gb
II2D Ex h IIIC T200°C Db
Tamb -25°C ... +200°C
IP: 66/68
MD: 20##
PESR/G1/8/SEP

DEVICE DESCRIPTION 2
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Nameplate H250/M40, DK37/M8M, DK37/M8M/R, H250/M8MG, H250/M8MG/R
Figure 2-10: Example of a nameplate for H250 M40 (ATEX)
Nameplate H250/M40, DK37/M8M, DK37/M8M/R, H250/M8MG, H250/M8MG/R
Figure 2-11: Example of a nameplate for H250 M40 (UKCA)

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•SN - serial number and/or PA - production order number
•MD - manufacturing date
•PS - max. operating pressure (Pressure Specified)
•PT max. - max. test pressure (Pressure Test max.)
•TS - max. operating temperature (Temperature Specified)
•PED / PESR - Pressure Equipment Directive / Pressure Equipment Safety Regulation
•Tag-No. - tag identifier
•Reg.No. - registration number
•Tamb. - max. ambient temperature
•VG - V number, Germany
•SO - order number
•PA - production order number
•AC - article code
Nameplate VA40, GA24, DK46, DK47, DK48, DK800
Figure 2-12: Example of a nameplate for VA40 (ATEX)
Nameplate VA40, GA24, DK46, DK47, DK48, DK800
Figure 2-13: Example of a nameplate for VA40 (UKCA)
XXXXXXXXX
XXXXXXXXX/XXX XXXXXXXXX XXXXXXXXXXXXXX
XXXXXXXXXXXXXX
XX
XXXXXXXXXX /XX/XX/XX
XXXXXX XXX
10020
CAUTION!
The values stated on the nameplates (indicated with XXX) vary according to the individual device
versions and can be found on the respective nameplate or standard manual for the device.

DEVICE DESCRIPTION 2
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2.4 Flammable products
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:
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.
The max. allowable operating pressure PS printed on the nameplate is to be considered.
The following versions require dust-free gases or liquids. Gases containing solid particles or
liquid droplets are not permitted. The products must reach the stated minimum conductivity.
The limit of the stated maximum nominal flow rate must be observed.
Device type Minimum conductivity in µS/m Maximum flow rate Qmax
H250/C... 0.01 -
VA40 0.001 5-times
GA24 - 10-times
DK46 / DK47
DK48 / DK800 - 20-times
DK46PV / DK47PV
DK48PV / DK800PV 0.001 20-times
Table 2-1: Minimum conductivity of product and maximum flow for the device type

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2.5 Equipment category
Variable area flowmeters are designed in category II 2G / II 2D for use in zone 1 or zone 2 or
zone 21 or zone 22. The inside of the measuring unit is also approved for zone 1.
2.6 Types of protection
Non-electrical variable area flowmeters are designed in the protection type "design safety c" in
accordance with ISO 80079-37.
The marking of the non-electrical versions for the device type is:
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.
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 type Gas range Dust range
DK32 / DK34 / DK37 II 2G Ex h IIC T6...T3 Gb II 2D Ex h IIIC T150°C Db
DK32 HT / DK34 HT
H250/M8MG II 2G Ex h IIC T6...T3 Gb II 2D Ex h IIIC T200°C Db
H250/M40 / H250/M40R II 2G Ex h IIC T6...T2 Gb II 2D Ex h IIIC T300°C Db
H250/M40 HT / H250/M40R HT II 2G Ex h IIC T6...T1 Gb II 2D Ex h IIIC T450°C Db
DK46 / DK47 / DK48 / DK800
VA40 II 2G Ex h IIC T6...T5 Gb II 2D Ex h IIIC T100°C Db
GA24 II 2G Ex h IIC T6...T4 Gb II 2D Ex h IIIC T120°C Db
Table 2-2: Marking of the non-electrical versions for the device type
II Explosion protection, group II
2 Equipment category 2
G Gas explosion protection
D Dust ignition protection
Ex h Non-electrical device - Protection through design safety
IIC Gas group, suitable for gas groups IIC, IIB and IIA
IIIC Dust group, suitable for groups IIIC, IIIB and IIIA
T6...T2 Temperature class range, suitable for temperature classes T6...T1
T300°C Maximum surface temperature of measuring unit
Gb EPL, suitable for zone 1 and zone 2
Db EPL, suitable for zone 21 and zone 22
Table 2-3: Description of the marking

DEVICE DESCRIPTION 2
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2.7 Ambient temperature / Product temperature
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.
The correlation of the temperature class as a function of the ambient temperature and the
process temperature is shown separately for each type series in the following table.
The permissible ambient temperatures and process temperatures can be reduced for functional
reasons.
Device type Temp.
class
Surface
temperature
Maximum permissible
Ambient temperature
in °C
Product temperature
in °C
DK32 / DK34 T6 T85°C -40...+70 -40...+85
T5 T100°C -40...+100
T4 T135°C -40...+135
T3 T150°C -40...+150
DK32 HT / DK34 HT T6 T85°C -25...+85 -25...+85
T5 T100°C -25...+100 -25...+100
T4 T135°C -25...+135 -25...+135
T3 T200°C -25...+200 -25...+200
DK37 / M8M T6 T85°C -40...+70 -40...+85
T5 T100°C -40...+100
T4 T135°C -40...+135
T3 T150°C -40...+150
H250 / M8MG T6 T85°C -40...+70 -40...+85
T5 T100°C -40...+100
T4 T135°C -40...+135
T3 T200°C -40...+200
H250 / M40
H250 / M40R
H250 / M40 HT
H250 / M40R HT
T6 T85°C -40...+70 -40...+85
T5 T100°C -40...+100
T4 T135°C -40...+135
T3 T200°C -40...+200
H250 / M40 T2 T300°C -40...+50 -40...+300
H250 / M40R -40...+65
H250 / M40 HT
H250 / M40R HT -40...+70
H250 / M40R HT -40...+120
Stainless steel type plate
H250 / M40 HT
H250 / M40R HT T1 T450°C -40...+70 -40...+450
H250 / M40R HT -40...+120
Stainless steel type plate
DK46 / DK47
DK48 / DK800 T6 T85°C -20...+85 -5...+85
T5 T100°C -20...+100 -5...+100

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VA40 T6 T85°C -20...+85 -20...+85
T5 T100°C -20...+100 -20...+100
GA24 T6 T85°C -20...+85 -40...+85
T5 T100°C -20...+100 -40...+100
T4 T120°C -40...+120
Table 2-4: Temperature class and surface temperature in °C
Device type Temp.
class
Surface
temperature
Maximum permissible
Ambient temperature
in °F
Product temperature
in °F
DK32 / DK34 T6 T185°F -40...+158 -40...+185
T5 T212°F -40...+212
T4 T275°F -40...+275
T3 T302°F -40...+302
DK32 HT / DK34 HT T6 T185°F -25...+185 -25...+185
T5 T212°F -25...+212 -25...+212
T4 T275°F -25...+275 -25...+275
T3 T392°F -25...+392 -25...+392
DK37 / M8M T6 T185°F -40...+158 -40...+185
T5 T212°F -40...+212
T4 T275°F -40...+275
T3 T302°F -40...+302
H250 / M8MG T6 T185°F -40...+158 -40...+185
T5 T212°F -40...+212
T4 T275°F -40...+275
T3 T392°F -40...+392
H250 / M40
H250 / M40R
H250 / M40 HT
H250 / M40R HT
T6 T185°F -40...+158 -40...+185
T5 T212°F -40...+212
T4 T275°F -40...+275
T3 T392°F -40...+392
H250 / M40 T2 T572°F -40...+122 -40...+572
H250 / M40R -40...+149
H250 / M40 HT
H250 / M40R HT -40...+158
H250 / M40R HT -40...+248
Stainless steel type plate
H250 / M40 HT
H250 / M40R HT T1 T842°F -40...+158 -40...+842
H250 / M40R HT -40...+248
Stainless steel type plate
DK46 / DK47
DK48 / DK800 T6 T185°F -20...+185 -5...+185
T5 T212°F -20...+212 -5...+212
Device type Temp.
class
Surface
temperature
Maximum permissible
Ambient temperature
in °C
Product temperature
in °C

DEVICE DESCRIPTION 2
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2.8 Surface temperature
It is to be assumed that a combustible fuel / air mixture can be in contact with the outer wall of
the measuring tube and process connections. Any temperature gradient between the internal
wall in contact with the product (product temperature) and the outer surface is not taken into
consideration.
The actual maximum surface temperature does not depend on the device itself, but instead on
the operating conditions. The device itself does not generate heat and, for this reason, the
surface temperature is determined by the product temperature and, in versions with heating
jackets, by the heating medium temperature as well.
The nameplate shows the maximum values of the temperature classes and the maximum
surface temperature. Depending on the device version, these values may not be reached.
The maximum permitted ambient and product temperatures can be found in the standard
manual.
VA40 T6 T185°F -20...+185 -20...+185
T5 T212°F -20...+212 -20...+212
GA24 T6 T185°F -20...+185 -40...+185
T5 T212°F -20...+212 -40...+212
T4 T248°F -40...+248
Table 2-5: Temperature class and surface temperature in °F
Device type Temp.
class
Surface
temperature
Maximum permissible
Ambient temperature
in °F
Product temperature
in °F

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2.9 Ignition hazard assessment / protective measures
Non-electrical variable area flowmeters were subject to an ignition hazard assessment in
accordance with ISO 80079-36. The following table lists the ignition hazards considered and the
protective measures carried out or to be carried out by the operator.
Device type Ignition hazard Constructive protective
measures
Construction site protective measures
(note special conditions!)
All versions Electrostatics Electrostatic connection
between conductive
components, ground
connection device
Include device in the equipotential bonding of
the hazardous area.
For installations in hazardous areas of
group IIC, observe the notes for the
elimination of electrostatic charge.
Impact of
sparking in
measuring units
Float stop in measuring unit Eliminate pressure surges in pipelines.
Impact of
sparking on
surfaces
Materials (without titanium) None
Shock
resistance
Glass cones
Tests with low energy If the degree of mechanical risk is higher,
protective measures on-site must be taken.
Shock
resistance
Metal cones
Tests with high energy None
Surface
temperatures None, as no self-warming occurs Note max. permissible product and ambient temperatures.
Oxygen in
conjunction with
titanium
measuring units
None Products with an oxygen content higher than
21% V/V are not permitted.
H250 M40 / H250
M8MG Impact of sparking on
titanium
surfaces
Marking in the type marking
(Ti) Equipment with titanium surfaces may only be used in shock-resistant areas.
DK32 / DK34 /
DK37 Marking with material code (e. g. 3.7025, 3.7035 or 3.7055)
on the measuring unit
H250/C... Electrostatics Minimum conductivity of the
medium ≥10-8 S/m
Note the minimum conductivity of the
medium.
VA40 Min. conductivity for liquids
≥10-9 S/m
Flow rate ≤5 * Vmax with dust-
free gases and liquids
Note the minimum conductivity of the
medium.
Note the maximum flow rate.
GA24 Flow rate ≤10 * Vmax with
dust-free gases and liquids
Note the maximum flow rate.
DK46 / DK47
DK48 / DK800 Flow rate ≤20 * Vmax with
dust-free gases and liquids
DK46PV / DK47PV
DK48PV / DK800PV Min. conductivity for liquids
≥10-9 S/m
Flow rate ≤20 * Vmax with
dust-free gases and liquids
Note the minimum conductivity of the
medium.
Note the maximum flow rate.
DK3x HT.. Corrosion None Exclude corrosive environmental conditions.
Table 2-6: Ignition hazard assessment / protective measures

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 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.
3.2 Special conditions
Equipotential bonding
Variable area flowmeters must be included in the equipotential bonding of the hazardous area.
For further information refer to
Grounding and equipotential bonding on page 18.
Electrostatics
If the installation takes place in hazardous areas of group IIC, the instructions for electrostatics
must be observed.
For further information refer to
Static electricity on page 21.
Mechanical tests
All-metal design:
Variable area flowmeters are tested on measuring units, optional valves and controllers for
shock resistance with 4 Joules in accordance with ISO 80079-36 for device group II with a low
degree of mechanical risk. The sight glass is not tested on all-metal variable area flowmeters.
The integrity of the sight glass is not relevant to explosion protection on these devices. If the
degree of mechanical risk is higher, additional protective measures must be taken on-site.
Glass devices:
Variable area flowmeters are tested on measuring units, transparent sight glasses and
controllers and protective covers for shock resistance with 4 or 2 Joules in accordance with
ISO 80079-36 for device group II with a low degree of mechanical risk. If the degree of
mechanical risk is higher, additional protective measures must be taken on-site.
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
Variable area flowmeters with titanium components are 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)!

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Flammable products
Observe the safety instructions when operating with flammable products.
For further information refer to
Flammable products on page 11.
Measuring units with titanium components
Observe the information regarding installation and safe operation.
For further information refer to
Mounting on page 17 and refer to Operation on page 21.
Unpainted indicators
Unpainted DK3x..HT indicators must not be used in corrosive environments.
3.3 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 ①or ②.
The location of the ground terminal is shown below according to type. This connection only
ensures electrostatic grounding of the device and does not meet the requirements for
equipotential bonding.
Figure 3-1: Ground terminal for DK3. mechanical flowmeter or DK32 with ESK3x transmitter
Figure 3-2: Ground terminal for H250/M40

INSTALLATION 3
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Figure 3-3: Ground terminal for DK37/M8M
Figure 3-4: Ground terminal for H250/M8MG
INFORMATION!
The indicator housing of M8M is made of conductive plastic. Friction cannot cause electrostatic
charge.
Figure 3-5: Ground terminal for DK46 / DK47 / DK 48 / DK800

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Figure 3-6: Ground terminal for VA40
Figure 3-7: Ground terminal for GA24
INFORMATION!
The grounding ①and ②are equivalent.
INFORMATION!
The temperature at the electrostatic equalisation connector on the DK32, DK34 and DK37
measuring units corresponds to the process temperature. It is thus the responsibility of the
operator to select the connecting cable according to the process temperature.