Kobold NBK-ATEX Series User manual

Operating Instructions
for
Bypass Level Indicator
Model: NBK-ATEX

NBK-03 to -33 ATEX
page 2 NBK-03 to -33 ATEX K10/0322
1. Contents
1.Contents ........................................................................................................ 2
2.Note .............................................................................................................. 3
3.Instrument Inspection .................................................................................... 4
4.Regulation Use ............................................................................................. 4
4.1Bypass Measuring Tube System ......................................................... 5
4.2Electrical Limit Switches (option) ......................................................... 5
4.3Reed Contact Resistance Chain
(ATEX: options ...2/...E/...R/...B/...4/...L/...K/...N) ................................. 5
5.Operating Principle ........................................................................................ 6
6.Mechanical Connection ................................................................................. 7
7.Electrical Connection .................................................................................... 9
7.1Limit contacts NBK-R, NBK-RT, NBK-RA ............................................ 9
7.2Wiring Diagram .................................................................................. 10
7.3Safety Instructions ............................................................................. 13
7.4Ground connection for ATEX models ................................................ 15
8.Commissioning............................................................................................ 16
9.Trouble Shooting ......................................................................................... 17
10.Maintenance ............................................................................................... 17
11.Technical Information .................................................................................. 18
12.Options ........................................................................................................ 26
13.Order Codes ............................................................................................... 31
14.Dimensions ................................................................................................. 32
15.EC Declaration of Conformance ................................................................. 37
16.Certificates .................................................................................................. 40
16.1NBK-EXAM ........................................................................................ 40
16.2Transmitter LOM ................................................................................ 48
16.3Limit contact RA (excerpt) .................................................................. 53
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim
Tel.: [phone]
Fax: [phone]
E-Mail: [email protected]
Internet: www.kobold.com

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 3
2. Note
Please read these operating instructions before unpacking and setting the unit into
operation. Follow the instructions precisely as described herein.
The instruction manuals on our website www.kobold.com are always for currently
manufactured version of our products. Due to technical changes, the instruction
manuals available online may not always correspond to the product version you
have purchased. If you need an instruction manual that corresponds to the
purchased product version, you can request it from us free of charge by email
([email protected]) in PDF format, specifying the relevant invoice number and
serial number. If you wish, the operating instructions can also be sent to you by
post in paper form against an applicable postage fee.
The devices are only to be used, maintained and serviced by persons familiar with
these operating instructions and in accordance with local regulations applying to
Health & Safety and prevention of accidents.
When used in machines, the measuring unit should be used only when the
machines fulfil the EC-guidelines.
Classification according to Pressure Equipment Directive 2014/68/EU
NBK-03 to NBK-33
Cate
g
or
y
assi
g
nment for dan
g
erous media
(
from dia
g
ram 1
)
Density
[kg/dm³]
PN
[bar
]
Category ML
[mm]
Category ML
[mm]
Category ML
[mm]
NBK-03
1,0
16
← Cat. II →
4711
← Cat. III →
6000 - / -
0,9/0,8/0,7/
0,6/0,54 4600 6000 - / -
NBK-06
1,0
40
1698 6000
← Cat. IV →
∞
0,9/0,8/0,7 1588 6000 ∞
NBK-07
1,0
63
1060 6000 ∞
0,9/0,8/0,7 950 6000 ∞
NBK-10
1,0
100
577 4084 ∞
0,9/0,8 467 3974 ∞
NBK-31
1,0
160
≤2090 5600
0,9 ≤2020 5600
0,8 ≤1900 5400
NBK-32
1,0
250
≤1180 5600
0,9 ≤1110 5600
0,8 ≤985 5400
NBK-33
1,0
320
≤1040 5600
0,9 ≤970 5500
0,8 ≤830 5400
ATTENTION! If the calculated bypass length is exactly within the range limit, then the stricter test method must be used

NBK-03 to -33 ATEX
page 4 NBK-03 to -33 ATEX K10/0322
Classification according to Pressure Equipment Directive 2014/68/EU
NBK-03 to NBK-33
Cate
g
or
y
assi
g
nment for not dan
g
erous media
(
from dia
g
ram 2
)
Density
[k
g
/dm³]
PN
[bar]
Kategorie ML
[mm]
Category ML
[mm]
Category ML
[mm]
Category ML
[mm]
NBK-03
1,0
16
← Cat. I →
4711
← Cat. II →
6000
← Cat. III →
6000 - / -
0,9/0,8/0,7/
0,6/0,54 4600 6000 6000 - / -
NBK-06
1,0
40
1698 6000 6000 - / -
0,9/0,8/0,7 1588 6000 6000 - / -
NBK-07
1,0
63
1060 6000 6000
← Cat. IV →
∞
0,9/0,8/0,7 950 6000 6000 ∞
NBK-10
1,0
100
577 4084 6000 ∞
0,9/0,8 467 3974 6000 ∞
NBK-31
1,0
160
≤2090 5600 - / -
0,9 ≤2020 5600 - / -
0,8 ≤1900 5400 - / -
NBK-32
1,0
250
≤1180 4410 5600
0,9 ≤1110 4340 5600
0,8 ≤985 4220 5400
NBK-33
1,0
320
≤1040 4090 5600
0,9 ≤970 4010 5500
0,8 ≤830 3870 5400
ATTENTION! If the calculated bypass length is exactly within the range limit, then the stricter test method must be used
3. Instrument Inspection
Instruments are inspected before shipping and sent out in perfect condition.
Should damage to a device be visible, we recommend a thorough inspection of the
delivery packaging. In case of damage, please inform your parcel service /
forwarding agent immediately, since they are responsible for damages during
transit.
Scope of delivery:
The standard delivery includes:
 Bypass Level Indicator model: NBK-…
4. Regulation Use
Any use of the Bypass level Indicator, model: NBK, which exceeds the
manufacturer’s specification, may invalidate its warranty. Therefore, any resulting
damage is not the responsibility of the manufacturer. The user assumes all risk for
such usage.
The NBK Bypass Level Indicator is used for continuous measurement, indication,
and monitoring of liquids in tanks, vessels, reservoirs, basins etc. The indication
occurs via a magnetically coupled roller indicator.

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 5
4.1 Bypass Measuring Tube System
The bypass tube is attached at the side of the vessel with a connecting flange or a
threaded pipe. The installation position is always vertical. The NBK should only be
used for liquids with the medium density specified on the nameplate. Otherwise the
indication will deviate (float too high or submerged).
Vessel inner pressure and medium temperature should not exceed the specified
maximum values, as this can lead to the destruction and malfunction of the bypass
system. It is imperative that the materials used are compatible with the liquid being
measured.
Proper operation is also impaired by:
 high degree of soiling
 suspended solids
 crystallisation
 ferrite particles
4.2 Electrical Limit Switches (option)
The optional electrical limit switches serve to signal a preset level.
For ATEX: NBK-RA: Bistable changeover contact as encapsulated proximity
switch fitted in metallic cast housing with 3 m connection cable.
4.3 Reed Contact Resistance Chain
(ATEX: options ...2/...E/...R/...B/...4/...L/...K/...N)
The optional reed contact resistance chain (model: MM..., see separate EC-Type
Examination Certificate LOM14ATEX2075X) converts the liquid level to a
resistance value. It serves to electrically transfer the level value. An optional
available transmitter converts the resistance value into a standard signal (e.g. 4-
20 mA).
Please pay attention to the maximum medium and ambient temperatures.

NBK-03 to -33 ATEX
page 6 NBK-03 to -33 ATEX K10/0322
5. Operating Principle
Kobold Bypass Level Indicators are used for continuous measurement, display and
monitoring of liquid levels. The bypass tube is attached onto the side wall of the
vessel.
According to the law of communicating tubes the level in the bypass tube equals
the level in the vessel. A float with embedded circular magnets in the bypass tube
follows the liquid level and transfers it in a non-contacting manner to a display or a
monitoring device fitted outside the tube. The following indication and monitoring
devices are available:
Magnetic roller indicator
As the float passes by, the red/white rollers are rotated in succession by 180°
around their own axes. The rollers change from white to red as the level rises and
from red to white as the level falls. The advantage of ball displays is the higher
protection category, good visibility of 180 ° and higher vibration resistance with
filled version. The level in a tank or a mixer is continuously displayed as a red
column, even when the power supply fails.
Transmitter
To remotely transmit the level a transmitter with an immersible magnetic probe
(chain of resistors) or a magnetostrictive transducer can be mounted outside the
bypass tube. The contacts of a reed contact chain are connected or disconnected
via the float movement in a non-contacting manner. Depending on the level the
number of connected resistors changes and as a consequence the output of the
total resistor value. A continuous standard signal of 4 to 20 mA is generated by
means of a fitted transmitter. This standard signal can then be displayed on
analogue or digital indicating devices.
Limit contacts
One or more reed contacts for limit-value acquisition or also for level control can
be attached to the bypass tube.
ATEX-version only NBK-03...NBK-10
The bypass level indicators are ATEX approved. For level evaluation, limit switches
and a magnetic submersible probe (reed contact chain) with ATEX approval are
offered. The electrical add-on parts have their own ATEX approval.
ATEX approval:
Bypass-level indicator: II 2G Ex mb IIC T5/T6 Gb
Limit contact NBK-RA: II 2D Ex mb IIIC IP67 T 105 °C Db
Reed Contact Resistance Chain: II 1GD Ex ia IIC T6 Ga
II 1/2G Exd II C T6 Ga/Gb
II 1/2D Ex tb IIIC T85 °C Da/Db

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 7
6. Mechanical Connection
Remove the bottom flange from the
bypass tube, and insert the
cylindrical float in the NBK bypass
tube with the designation "TOP"
upturned. Reposition the gasket
and close the bottom flange again;
firmly tighten with screws.
Mount the bypass tube to the
vessel to be monitored via the
process connection and seal with
an appropriate device. Normally it
is sufficient to fix the complete NBK
with both process connections.
However the NBK should be
subjected to constant shock or
strong vibrations it is
recommended that the instrument
is secured with rubber-damped
tube clips. No welding is allowed on
the bypass tube.
Mount and tighten the magnetic
roller indicator - if not already
mounted - on the bypass tube with
the two provided ribbon clamps.
Mount and tighten the reed switch - if available - on the bypass tube at the opposite
side of the roller indicator with the provided ribbon clamps (ex contact: two ribbon
clamps). The height of the switch contacts may be selected at will. The cable connec-
tion must point downwards. The switch must be attached close to the bypass tube. The
switching function of the switch is impaired by an enlarged air gap.

NBK-03 to -33 ATEX
page 8 NBK-03 to -33 ATEX K10/0322
Mount and tighten the remote sensor -
if available and not already mounted - on
the bypass tube with the ribbon clamps.
The remote sensor must fully cover both
process connections. The cable terminal
box is situated at the top.

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 9
7. Electrical Connection
7.1 Limit contacts NBK-RA
Attention!
Observe the allowed electrical ratings for the limit switch.
Maximum values
NBK-RA
ATEX-
contact
Switching capacity: 45 W/VA
Switchin
g
current: 0,6
A
Switching voltage: 230 VAC/DC
Install the switch (if available) according to the diagram and connect it to the
electrical controller.
When switching inductive loads, such as contactors, relays, etc., electrical limit
values should not, also temporarily, be exceeded by e.g. voltage peaks. The use
of a contact protection relay is recommended to avoid overloading the reed
contacts.
Valid regulations for hazardous areas and regulations for installation (DIN/VDE
0165) should be observed when installing the NBK level indicator in zone 1 or 2
hazardous areas (no combustible liquids).
Note to NBK-RA:
Protect the circuit of the limit contact with a fuse. This fuse
must tolerate the permitted nominal current of the switching
contact and must have a deactivating ability according to the
possible short circuit current of the power system at the place
of installation. The contact is activated by the North Pole of a
magnet and deactivated by its South Pole.
NBK-RA
A
TEX- contact
brown
blue
black

NBK-03 to -33 ATEX
page 10 NBK-03 to -33 ATEX K10/0322
7.2 Wiring Diagram
 Ensure that the electrical supply lines are powerless.
 To avoid faults caused by electrical fields from other circuits, the cables should not
be installed adjacent to other high voltage power lines.
 Unscrew cover and run supply lines through cable gland.
 Connect the remote sensor to the electronics according to the following table.
7.2.1 Reed Contact Chain Resistor Output
(ATEX options ...2/...4)
Resistance value
increases
proportionally
with level
increase.
Resistance value
decreases
proportionally
with level
increase.
Signal
Internal* White Brown Green
Models with box Clamp 1 Clamp 2 Clamp 3
*Please note: The colours of internal cables are for internal connections
only and therefore are only visible in transmitters with terminal
connection box

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 11
7.2.2 Reed Contact Chain TRANSMITTER Output
(Options ...E/...R/...B/...L/...K/...N)
7.2.3 Reed Contact Chain TRANSMITTER Output with display
LED display (option …L/…K + option LE or KE)
LCD display (option ...L/...K +option LC or KC)
(ii) For programming instructions of different transmitter models please
consult separate instruction manuals of respective transmitters.

NBK-03 to -33 ATEX
page 12 NBK-03 to -33 ATEX K10/0322
Electrical connection in intrinsically safe mode Ex ia
Electrical connection in explosion-proof safe mode Ex d

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 13
7.3 Safety Instructions
7.3.1 Area of validity
These safety instructions apply to MM…E Series of magnetic level switch for use in
explosion-proof atmospheres conforming to CE certificate LOM 06ATEX2054 X and
MM…F Series conforming to CE certificate LOM 14ATEX2075 X
7.3.2 Guidelines
These safety instructions must be applied to the MM…E and MM…F Series used in
gas explosion hazard environments.
It is necessary to follow carefully the instructions from the hazardous areas where
the MM...E or MM…F will be installed, as well as, the safety instructions included in
this manual and the safety regulations of the ATEX certificate (see appendix).
In models with transmitter and/or display, the intrinsically safe specific parameters
are:
Ci total: Ci (sensor) + Ci (transmitter) + Ci ( display)
Li total: Li (sensor) + Li (transmitter) + Li ( display)
It must be considered the minimum value of Pi, Ii and Ui, in all components used in
the assembly.
Temperature class and/or surface temperature relates only to a device operated at
ambient temperature. On installation, the actual temperature class for process
operation has to be determined.
Inlet bushing and cable glands must conform to the certification for their type in
accordance with the directive.
The use in zone 0 of heads made of aluminium should be restricted to locations
where the risk of ignition due to mechanical impact is not probable.
Verify that all data written on the label of the device matches the data required for
the installation.
Verify that there is no mechanical stress or deformation due to installation in the
tank.
Remove power supply and verify that no explosion risk is present before opening
the housing cover and check that the cover is correctly mounted before applying
power to the instruments MM…F Series.
The installation of instruments in hazardous areas must be exclusively done by
trained staff.

NBK-03 to -33 ATEX
page 14 NBK-03 to -33 ATEX K10/0322
7.3.3 Protection against ESD (Electro Static Discharges)
Instruments with plastic parts that can produce Electro Static Discharges, have a
label for it.
It is important to follow some rules to avoid ESD:
- Avoid rubbing the device.
- Never clean the device in dry.
- Do not install the device near material airflows or near steam outlets.
7.3.4 Chemical resistance
Ensure that the device construction materials have chemical resistance sufficient
to prevent mechanical deformations that may affect the device. The responsibility
for suitability and intended use lies solely with the operator.
7.3.5 Maintenance and repairs
The instrument does not require maintenance or servicing. By measuring
substances, which tend to deposit and contamination, cleaning may be necessary.
Repairs must be only carried out by Kobold Mesura (manufacturer).
7.3.6 Storage
Measuring instruments should be protected against humidity and dust.
Storage temperature: -5…+55 ºC

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 15
7.4 Ground connection for ATEX models
The bypass has to be integrated into the potential equalisation system of the
installation. This can be carried out through the earth terminal which is shown in
the following drawing:
Potential equalisation

NBK-03 to -33 ATEX
page 16 NBK-03 to -33 ATEX K10/0322
8. Commissioning
Because of the setting behaviour of seals, all screw connections must be
retightened.
Fill vessel and switch on electrical controller, if available. If there are gate valves
between bypass process connection and tank, first slowly open the upper valve
(pressure equalisation) and then the lower valve (liquid side). If vent and drain
valves have been installed, close them before filling.
The liquid that now enters the bypass tube raises the float until the level between
tank and bypass tube is balanced. The roller indicator indicates the liquid level.
Commissioning electrical reed switches NBK-RA
Function of switches
All switches have three connection poles (black (2), blue (1) and brown (3)).
The black wire (2) is the common pole for both switching functions
(N/C and N/O contact).
The float must pass the switch once in both directions so that the switching function
is in line with the terminal connection diagram and table below.
These instructions are often ignored when an alarm lamp is connected directly with
the result that the alarm lamp incorrectly indicates a fault.
When the switch has been passed, it is ready for operation and requires no
maintenance.
black
(
2
)
/ blue
(
1
)
black
(
2
)
/ brown
(
3
)
float above open closed
float below closed open
Hysteresis
Hysteresis is the difference between contact closing and opening points. A
hysteresis of approximately 15 mm float travel is achieved by factory tuning of the
float magnet and contact strength.

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 17
9. Trouble Shooting
Error: The tank is full but there is no indication
 Check that both flanges (process connection), top and bottom, are open to the
vessel, and that the bypass tube fills with liquid.
 Check that there is a float in the system.
 When the float is installed, check whether it is being blocked by foreign objects
or dirt deposits.
Error: The tank is full but the indication is too low.
 Check that the density of the liquid is the same as the density given on the
nameplate.
 Check that the float has been correctly installed with the marking "TOP"
upturned.
 Check if dirt deposits in the bypass tube are blocking the float.
10. Maintenance
The drain plug should be opened occasionally, to wash out any deposits in case
the liquid to be measured contains dirt particles, which could settle in the bypass
tube.
If crust formation or crystallisation has taken place, the tank must be emptied or
shut off; the lower cover flange must then be removed. The float should then be
taken carefully out of the bypass. The bypass tube can now be mechanically
cleaned.
The inspection window for the roller indication is made of high-quality plexiglass
(glass for high-temperature display). It should be cleaned with a suitable cleaning
agent.
The indicator requires no further maintenance.

NBK-03 to -33 ATEX
page 18 NBK-03 to -33 ATEX K10/0322
11. Technical Information
Process Connection: flange DIN EN 1092-1, type 11, form B,
DN 15, DN 20, DN 25, DN 32
DN 40, DN 50,
Flange ASME B 16.5 RF-2009
½”, ¾”, 1”, 1¼”, 2”
R-Thread DIN EN 10226-1
½“, ¾”, 1”, 1¼”
NPT ANSI/ASME B1.20.1
½“, ¾”, 1”, 1¼”
Bypass tube: Ø 60,3 mm, 1.4571 (NBK-03/.../10)
Ø 71,0 mm, 1.4571 (NBK-31)
Ø 76,1 mm, 1.4571 (NBK-32/33)
NBK-03,-06,-07: flat gasket: <200 °C: PTFE;
≥200 °C: Klinger SIL®
NBK-10: reinforced graphite
NBK-31/32/33: RTJ-seal
Operating pressure: PN 16/40/63/100/160/250/320
Operating temperature: -40 °C...+400 °C (ceramic rollers)
-20...+120 °C (POM rollers)
-104...+200 °C (ball display)
-60...+100 °C (NBK-31, -32, -33)
Viscosity: max. 200 mm2/s standard
(Option: up to max. 460 mm2/s for NBK-03)
Max. measuring length: up to 5500 mm: single-part,
longer two-part or multipart
Overall length: see dimension drawing
Roller display RP (max. length 5500 mm)
Material roller: POM
Display glass: PMMA
Carrier frame material: Aluminium, black anodised
Operat. temperature: -20 °C...100 °C
Protection: IP54
Approval: ATEX
Roller display RK (max. length 5500 mm)
Material roller: Ceramic
Display glass: Borosilicate glass
Carrier frame material: Aluminium, black anodised
Operat. temperature: -40 °C...400 °C
Protection: IP54
Approval: ATEX

NBK-03 to -33 ATEX
NBK-03 to -33 ATEX K10/0322 page 19
Ball display model KP (max. length 3800 mm one-piece)*
Material ball: PA
Sight tube: PMMA
Sealing plug: Aluminium
Seal: NBR
Ball support rail: Aluminium, black anodised
Carrier frame: Stainless steel 1.4301
Scale: PVC, stainless steel 1.4301 (option MV)
Medium temperature: -20...+80 °C
Ambient temperature: -20...+80 °C
Protection: IP66
Ball display model KM (max. length 3800 mm one-piece)*
Material ball: PA – high temperature strength
Sight tube: PC
Sealing plug: Aluminium
Seal: FKM
Ball support rail: Aluminium, black anodised
Carrier frame: Stainless steel 1.4301
Scale: PVC, stainless steel 1.4301 (option MV)
Medium temperature: -60...+120 °C
Ambient temperature: -20...+80 °C
Protection: IP66
Ball display model KF (max. length 3800 mm one-piece)*
Filling: silicone oil
Material ball: PA – high temperature
Sight tube: PC
Sealing plug: Stainless steel, 1.4571
Seal: FKM
Ball support rail: Aluminium, black anodised
Carrier frame: Stainless steel 1.4301
Scale: PVC, stainless steel 1.4301 (option MV)
Medium temperature: -104...+120 °C
Ambient temperature: -20...+80 °C
Protection: IP66
Ball display model KG (max. length 3000 mm one-piece)*
Material ball: PA – high temperature strength
Sight tube: Borosilicate glass
Sealing plug: Stainless steel, 1.4571
Seal: FKM
Ball support rail: Aluminium, black anodised
Carrier frame: Stainless steel 1.4301
Scale: stainless steel 1.4301
Medium temperature: -20...+200 °C
Ambient temperature: -20...+200 °C
Protection: IP66
* in case of multi port design, a display length from 32 mm is not readable

NBK-03 to -33 ATEX
page 20 NBK-03 to -33 ATEX K10/0322
ATEX approval
ATEX limit contact, model NBK-RA
Contact operation: bistable changeover contact encapsulated
Switching hysteresis: approximately 15 mm
Max. switching capacity: 45 VA; 230 V
AC/DC
; 0.6 A
Temperature class: T5 / T6
Max. ambient temperature: 70 °C / 85 °C
Connection: 3 m PVC cable
Housing: metallic, cast (GD-ZN AI 4 Cu1)
Protection: IP 67
ATEX marking: II 2G Ex mb IIC T5/T6 Gb
II 2D Ex mb IIIC IP67 T105°C Db
ATEX reed contact resistor chain model: …2...
In protection type intrinsically safe Ex ia IIC only for connection to a
certified intrinsically safe current loop with the following maximum values:
Total resistance: 0.7...7 kΩ
Max. voltage: U
I
= 24 V
Max. capacity: Pi = 1.2 W
Temperature class: T6
Resolution: 10 mm
Housing: Aluminium pressure cast
Protection: IP65
ATEX marking: Ex II 1GD Ex ia IIC T6 Ga
ATEX immersible reed contact resistor chain options E/R/B only in
connection with external intrinsically safe power supply