Page 1
Operating Instructions
for
Bypass Level Indicator
Model: NBK
Page 2
NBK
page 2 NBK K01/0906
1. Contents
1. Contents........................................................................................................2
2. Note ..............................................................................................................3
3. Instrument Inspection....................................................................................4
4. Regulation Use..............................................................................................4
4.1. Bypass Measuring Tube System .........................................................4
4.2. Electrical Limit Switches (option) .........................................................5
4.3. Remote Sensor with Reed Contact Chain of Resistors
(option ..M.. / option ..W..) ...................................................................5
4.4. Remote Sensor with Magnetostrictive Pick-Up (option ..T..)................ 5
5. Operating Principle........................................................................................5
6. Mechanical Connection.................................................................................7
7. Electrical Connection ....................................................................................9
7.1. Limit contacts NBK-R, NBK-RT ...........................................................9
7.2. Remote Sensor: Reed Contact Chain of Resistors (option ..W..) ......10
7.3. Remote Sensor: Chain of Resistors with 2-wire Transmitter
(option ..M..).......................................................................................11
7.4. Remote Sensor: Magnetostrictive Sensor with 4-wire Transmitter
(option ..T..) .......................................................................................12
8. Commissioning............................................................................................13
9. Trouble Shooting.........................................................................................14
10. Maintenance ...............................................................................................14
11. Technical Information..................................................................................15
12. Options........................................................................................................ 17
13. Order Codes ...............................................................................................18
14. Dimensions .................................................................................................19
15. Declaration of Conformance .......................................................................20
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim
Tel.: +49(0)6192-2990
Fax: +49(0)6192-23398
E-Mail: info.de@kobold.com
Internet: www.kobold.com
Page 3
NBK
NBK K01/0906 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 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 EWG-guidelines.
as per PED 97/23/EG
Model
Total bypasslength
p
max
[bar]
Medium non
dangerous
(Diagr. 2)
Medium dangerous
(Diagr. 1)
NBK-01 <= 645 16 Art.3, Para.3 Art.3, Para.3
NBK-01 <= 1270 16 Art.3, Para.3 I
NBK-01 <= 5040 16 I II
NBK-01 >= 6420 16 II III
NBK-03 <= 645 16 Art.3, Para.3 Art.3, Para.3
NBK-03 <= 1270 16 Art.3, Para.3 I
NBK-03 <= 5040 16 I II
NBK-03 >= 6420 16 II III
NBK-04 <= 645 16 Art.3, Para.3 Art.3, Para.3
NBK-04 <= 1270 16 Art.3, Para.3 I
NBK-04 <= 5040 16 I II
NBK-06 <= 250 40 Art.3, Para.3 Art.3, Para.3
NBK-06 <= 500 40 Art.3, Para.3 I
NBK-06 <= 2000 40 I II
NBK-06 <= 6500 40 II III
NBK-07 <= 167 64 Art.3, Para.3 Art.3, Para.3
NBK-07 <= 335 64 Art.3, Para.3 I
NBK-07 <= 1341 64 I II
NBK-07 <= 6500 64 II III
NBK-10 <= 107 100 Art.3, Para.3 Art.3, Para.3
NBK-10 <= 215 100 Art.3, Para.3 I
NBK-10 <= 858 100 I II
NBK-10 <=4292 100 II III
NBK-10 <= 6500 100 III IV
NBK-12; 13; 14 <= 1470 6 Art.3, Para.3 Art.3, Para.3
NBK-12; 13; 14 <= 2974 6 Art.3, Para.3 I
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NBK
page 4 NBK K01/0906
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
• Operating Instruction
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.
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
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NBK K01/0906 page 5
4.2. Electrical Limit Switches (option)
The optional electrical limit switches serve to signal a preset level.
NBK-R: Bistable changeover contact fitted in a polycarbonate housing with 3m
connection cable
NBK-RT200/-RT400: Bistable changeover contact fitted in an aluminium die cast
housing with terminal connectors
4.3. Remote Sensor with Reed Contact Chain of Resistors
(option ..M.. / option ..W..)
The optional remote electrical sensor converts the liquid level to a resistance
value, which serves to transmit the level as a varying electrical signal. Downstream control electronics transform the signal to a standard analogue value
(e.g., 4–20 mA), or control the level.
4.4. Remote Sensor with Magnetostrictive Pick-Up
(option ..T..)
Remote level transmission can be achieved by mounting a magnetostrictive
sensor outside the bypass tube. A continuous standard 4 to 20 mA signal is
obtained with a built-in transmitter. This signal can then be displayed on analogue
or digital indicators.
Please pay attention to the maximum medium and ambient temperatures.
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 fitted outside the tube or to a monitoring device. The following indication
and monitoring devices are available:
Page 6
NBK
page 6 NBK K01/0906
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 level in a tank or a mixer is continuously
displayed as a red column, even when the power fails.
Transmitter
To remotely transmit the level a transmitter with a 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.
Universal indicating unit
A universal indicating unit of type series ADI can be mounted on the bypass to
display and evaluate the standard signal (4–20 mA) generated by the transmitter.
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
The bypass level indicators can be supplied with ATEX approval. As an option
limit contacts and a reed contact chain with ATEX approval are available for level
measurement and monitoring.
ATEX approval:
Bypass-level indicator: Ex II 1G /2GD (mechanical)
Limit contact NBK-RA: Ex II 2G EEx m II T6 / T5
Immersible magnetic probe
(Reed contact chain): Ex II 1G EEx ia IIC T6
Transmitter for Reed chain: Ex II (1) G [EEx ia] IIC
GL version
In the pressure stages PN 16 (NBK-03) and PN 40 (NBK- 06) the bypass level
indicators are available with GL approval (Germanischer Lloyd). The magnetic
roller indication as well as limit contacts and a reed contact chain can be
delivered for level indication and evaluation .
Certificate-No. GL: 79 786-95 HH
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NBK K01/0906 page 7
6. Mechanical Connection
Remove bottom flange from bypass
tube, and insert the cylindrical float in
the NBK bypass tube with the designation "TOP" at the top. Re-position 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
should the NBK 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 connection 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.
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NBK
page 8 NBK K01/0906
The
high temperature switch will be
mounted to the bypass tube with the tube clip
fixed at the contact housing.
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.
Th
ermal screenin
g
(for 400°C-switch only)
Clamp
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NBK
NBK K01/0906 page 9
3
1
2
brown
black
blue
With cable connection
Connection box
7. Electrical Connection
7.1. Limit contacts NBK-R, NBK-RT
Attention!
Observe the allowed electrical ratings for the limit switch.
Maximum values
NBK-R
Standard
contact
NBK-RT
High temperature
contact
Switching capacity: 60 W/VA 80 VA
Switching current: 1 A 1 A
Switching voltage: 230 V
AC/DC
250 V
AC/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 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).
NBK-R
NBK-RT
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7.2. Remote Sensor:
Reed Contact Chain of Resistors (option ..W..)
• 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.
Transmitter
"top"
Transmitter
"bottom"
Pick-off
Silicon cable
White brown green
PVC cable
White brown green
FEP cable
brown blue black
Adapter box
terminal 1 terminal 2 terminal 3
Internal*
yellow red black
*Please note: The colours of internal cables are for internal
connections only and therefore are only visible in transmitters with
terminal connection box.
When connecting remote sensors to a Kobold transmitter, for example models
DFA, DST or DFM, please read the relevant operating instructions.
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NBK K01/0906 page 11
7.3. Remote Sensor: Chain of Resistors with
2-wire Transmitter (option ..M..)
• 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 wiring diagram
below.
+
-
+
-
16-32 V D
C
+
-
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NBK
page 12 NBK K01/0906
7.4. Remote Sensor: Magnetostrictive Sensor with
4-wire Transmitter (option ..T..)
• 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 terminal con-
nection diagram below.
4-20 mA
24 VDC
± 20%
Aout AGND +US GND
GND
+Us
AGND
AOUT
+
-
4-20 mA
24 V DC
+
-
Page 13
NBK
NBK K01/0906 page 13
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 relief) 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
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.
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page 14 NBK K01/0906
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" at the
top.
• 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
removed 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.
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NBK K01/0906 page 15
11. Technical Information
Process Connection: Flange DIN EN 1092-1, type 11, form B,
ANSI flange
R-thread DIN EN 10266-1
NPT thread
DN 15, DN 20, DN 25, DN 32
Bypass tube: Ø 60.3 mm, 1.4571
Flat gasket
NBK-03,-06,-07:
<200 °C: PTFE; ≥200 °C: Klinger SIL
NBK-10: graphite with insert
Operating pressure: PN 16/40/64/100
Service temperature: up to 120 °C: PP rollers,
up to 400 °C: ceramic rollers
Viscosity: max. 200 mm
2
/s
Max. measuring length: up to 6000 mm: single-part,
>6000 mm: two-part or multipart
Overall length: see dimension drawing
Technical Information for additional components
Limit contacts model NBK-R
Contact operation: bistable changeover contact
Switching hysteresis: approximately 15 mm
Max. switching capacity: 60 W/VA; 230 V
AC/DC
; 1 A
Resistance: 100 m
Medium temperature: max. 100 °C
Ambient temperature: max. 75 °C
Connection: 3 m PVC cable
Housing: polycarbonate
Protection: IP 67
Limit contacts high temperature
model NBK-RT200, NBK-RT400
Contact operation: bistable changeover contact
Switching hysteresis: approximately 15 mm
Max. switching capacity: 80 VA; 250 V
AC/DC
; 1 A
Resistance: < 20 m
Medium temperature: max. 200 °C / 400 °C
Ambient temperature: max. 145 °C / 350 °C
Housing: aluminium pressure-cast housing,
terminal connectors
Protection: IP 65
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page 16 NBK K01/0906
Reed contact resistor chain model: ...W...
Total resistance: approx. 5 k
Measuring-circuit voltage: max. 24 V
DC
Measuring current: max. 0.1 A
Medium temperature: max. 200 °C
400 °C with thermal screening
(option N)
Ambient temperature: max. 130 °C
Resolution: 10 mm (ML < 2000 mm)
20 mm (ML 2000 mm)
Housing: Aluminium pressure-cast
Protection: IP 65
Reed contact resistor chain
with 2-wire transmitter model: ...M...
Output: 4-20 mA
Power supply: 16-32 VDC
Load: (U
B
-9V)/0.02A []
Medium temperature: max. 120 °C
Ambient temperature: max. 80 °C
Resolution: 10 mm (ML < 2000 mm)
20 mm (ML 2000 mm)
Protection: IP 65
Magnetostrictive sensor
with 4-wire transmitter model: ...T...
Output: 4-20 mA
Power supply: 24 V
DC
, max. 150 mA
Load: max. 500
Max. length: 4000 mm
Medium temperature: max. 120 °C
Ambient temperature: max. 80 °C
Accuracy: ± 1mm
Housing: Aluminium pressure-cast
Protection: IP 65
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NBK K01/0906 page 17
12. Options
Options NBK-03…
• B*- indicating unit type ADI-B with bargraph,
rugged aluminium casing mounted on bypass tube,
for description see brochure Z2
• C*- indicating unit type ADI-K with bargraph and digital
display, rugged aluminium casing, mounted on
bypass tube, for description see brochure Z2
• D*- indicating unit type ADI-D with digital display,
rugged aluminium casing, mounted on bypass tube,
for description see brochure Z2
• A- connecting flange for two-part design
• E5- drain flange DN 20 stainless steel 1.4571
• E6- drain flange DN 25 stainless steel 1.4571
• F1- drain valve NAD-MZ 15 G1/2, stainless steel 1.4571
• F2- drain valve NAD-MZ15 1/2 NPT, stainless steel 1.4571
• H3- rinsing connection DN15, PN16, top and bottom for NBK-03
• H4- rinsing connection 1/2" ANSI, 150 lbs, top and bottom for NBK-03
• K- Armaflex insulation (thermal conductance 0.025 kcal/m °C, up to 105 °C)
• M1- Measuring scale up to 400°C, aluminium backing, engraved scale
• M2- Measuring scale up to 120°C, aluminium backing with polyester foil scale
• N- thermal screening for transmitter type ...W...: 200-400 °C
• P- radiographic examination DIN 54 111 T1
• Q- dye penetration test DIN EN 571-1
• X- pressure test with water 1.5 x PN
• Z- 3.1 certificate according to EN 10204
*Use only with option T (magnetostrictive measuring sensor)
or option M (resistor chain with measuring transducer)
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page 18 NBK K01/0906
13. Order Codes
Order Details (Example: NBK-03 F15 00 0 A)
Model
Nominal
pressure
Connection Nominal size
Roller
indication
Transmitter
Medium density
Float
NBK-03...
NBK-06...
NBK-07...
NBK-10...
PN 16/150 lbs
PN 40/300 lbs
PN 63/600 lbs
PN 100/1500 lbs
F=DIN flange
A=ANSI flange
R=R thread
N=NPT thread
15=DN 15,
1
/
2
"
20=DN 20,
3
/
4
"
25=DN 25, 1"
32=DN 32, 1
1
/
4
"
00= without
RP= PP rollers
RK= ceramic
rollers
0 = without transmitter
T = magnetostrictive
W = chain of resistors
M = chain of resistors
and transmitter
A=1.0 kg/dm3, titanium
B=0.90 kg/dm
3
, titanium
C=0.80 kg/dm
3
, titanium
D=0.70 kg/dm
3
, titanium
E=0.60 kg/dm
3
, titanium
F*=0.54kg/dm
3
,titanium
NBK-R
Standard limit contact (bistable changeover contact)
NBK-RT200
High-temperature limit contact max. 200°C
NBK-RT400
High-temperature limit contact max. 400°C
*not possible with NBK-10
Please specify measuring length L, density, pressure and temperature in writing !
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NBK K01/0906 page 19
14. Dimensions
NBK-... NBK-...
with roller indication with magnetostrictive transmitter
Dimensions NBK
NBK 10 always without ventilation
screw and drain screw.
Clearance dimension A [mm]
Medium density
Model Nominal pressure
0,54 [kg/dm
3
] 0,6 [kg/dm3] 0,7 [kg/dm3] 0,8 [kg/dm3] 0,9 [kg/dm3] 1 [kg/dm3]
NBK-03...
PN 16 / 150 lbs 320 320 320 320 320 210
NBK-06...
PN 40 / 300 lbs 410 410 320 320 320 210
NBK-07...
PN 63 / 600 lbs 410 410 320 320 320 210
NBK-10...
PN 100 / 1500 lbs - 700* 410** 320 320 210
*800 at instruments with thermal screening; **450 at instruments with thermal screening
Dimensions [mm]
Model Nominal pressure
B C D
NBK-03...
PN 16 / 150 lbs 130 110 115
NBK-06...
PN 40 / 300 lbs 130 110 115
NBK-07...
PN 63 / 600 lbs 130 130 180
NBK-10...
PN 100 / 1500 lbs 130 130 195
57
73,15
80
75
275
200
Measuring length L
60
A
C
D
O 60,3
Ventilation scre
w
Drain screw
Page 20
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15. Declaration of Conformance
We, KOBOLD Messring GmbH, Hofheim-Ts, Germany, declare that the
limit contacts for bypass level indicator fulfil the following standards:
Model
Pressure
stage
Category
as per PED
EC type
examination test
NBK-01
PN 16 III 43 629-02 HH
NBK-03
PN 16 III 43 629-02 HH
NBK-06
PN 40 III 43 630-02 HH
NBK-07
PN 63 III 43 626-02 HH
NBK-10
PN 100 IV 43 627-02 HH
The limit contact for bypass level indicators
NBK-R, NBK-RT are in conformity
with the standards noted below:
DIN EN 61010-1 1994-03
Safety requirements for electrical measuring, control and laboratory instruments
EN 60529, DIN VDE 0470-1 1992-11
Protection type through case (IP code)
The bypass level indicator with remote sensor
model NBK-...M...
model NBK-...T...
model NBK-...W...
to which this declaration relates is in conformity with the standards noted below:
EN 61326: 1997 +A1: 1998 +A2:2001
Electrical equipment for measurement, control and laboratory use
- Noise immunity: according EN 61326/A1 Amendment B table B.1
Criteria: according table 2, continuos not monitored operation
- Generic emission standard: according EN 61326/A1
Limit values: according table 4, equipment of class B
EN 60529, DIN VDE 0470-1 1992-11
Protection type through case (IP code)
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NBK K01/0906 page 21
Also the following EWG guidelines are fulfilled:
73/23 EWG Low voltage guideline
89/336/EWG Electromagnetic compatibility
97/23/EG PED
Category III (IV), Table 1, pipe, Group 1 dangerous fluids
Module B+D, mark CE0098
Notified body: Germanischer Lloyd Germany
Hofheim, 04. June 2004
H. Peters M. Wenzel
General Manager Proxy Holder
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