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Brand: KOBOLD
KOBOLD BGN All-Metal Variable Area Flow Meter, up to 350 °C
Description
All-metal rotameter for hot, aggressive and high-pressure lines
The KOBOLD BGN is an all-metal variable area flow meter for liquids and gases in pipes. The fluid flows upward through the meter tube and lifts a conical float until the annular gap between the float and the meter ring balances the forces on the float. A magnet transfers the float position to a follow magnet and pointer, so the flow is read on a scale in volume or mass per unit time, and the display works without auxiliary power.
The BGN is designed for rough conditions: wetted materials include stainless steel 1.4404/316L and 1.4571/316Ti, Hastelloy C-22 and a PTFE-lined version, the standard pressure rating is PN 40 and the process temperature reaches +350 °C. Options add inductive or micro switches, a 4 to 20 mA transmitter with HART or FOUNDATION Fieldbus, a counter module, heating or cooling, damping, a self-draining body and a flow controller.
Technical specifications
| Parameter | Specification |
|---|---|
| Measuring range, water | 0.5 to 5 l/h up to 13 000 to 130 000 l/h (1000 kg/m³, 1 mPa·s) |
| Measuring range, air | 0.015 to 0.15 Nm³/h up to 240 to 2400 m³/h (20 °C, 1.013 bar) |
| Versions | BGN-S stainless steel tube (up to 350 °C); BGN-P stainless steel with PTFE lining (up to 125 °C); BGN-H Hastelloy C-22 tube (up to 350 °C) |
| Accuracy | Liquid ±1.6 % full scale (BGN-S/H), ±2.0 % (BGN-P); gas ±1.8 % (BGN-S/H), ±2.2 % (BGN-P); transmitter adds ±0.2 %; repeatability ±0.5 % |
| Nominal pressure | PN 40 and ASME CL150 / CL300 (BGN-S/H); PN 16 and CL150 (BGN-P); optional up to 600 bar |
| Process temperature | -40 to +200 °C; -40 to +150 °C with electrical output; -40 to +350 °C with option V, H or W; -40 to +125 °C (BGN-P) |
| Ambient temperature | -40 to +80 °C; -40 to +65 °C with limit switch |
| Connections | Flanges EN 1092-1, ASME B16.5, DIN 2512, JIS; NPT; screw pipe connection; DN 15 to DN 150 |
| Display | Aluminium (stove-enamelled) or stainless steel; IP65, IP66 or IP67 (stainless housing) |
| Electrical outputs | NAMUR inductive switches SJ 3,5-N or SJ 3,5-SN, up to two micro changeover switches, transmitter ES 4 to 20 mA (14 to 30 VDC) with HART or FOUNDATION Fieldbus |
| ATEX | Mechanical device II 2G Ex h IIC T1…T6 Gb, II 2D Ex h IIIC T85 °C/T350 °C Db; transmitter ES II 2G Ex ia IIC T6 Gb; switches II 2G Ex ia IIC T6…T1 Gb |
| Other approvals | IECEx, KCS, NEPSI and PESO certificates listed for the transmitter |
Selecting the range and size
The order tables list the measuring range, size and pressure loss together. A few examples for water: 25 to 250 l/h in DN 15 with 60 mbar maximum pressure loss, 100 to 1000 l/h in DN 25 with 60 mbar, 1000 to 10 000 l/h in DN 50 with 110 mbar, and 8000 to 80 000 l/h in DN 100 (PN 16) with 600 mbar. Gas measurement is not available for the largest ranges of 10 000 l/h and above in DN 125 and DN 150.
Choose the range so that the normal flow sits in the upper part of the scale; the accuracy is given as a percentage of full scale, so low readings carry a larger relative error. The datasheet asks for the medium, density, viscosity, operating pressure and temperature to be specified in plain text with the order.
Special versions and ordering
The order example is BGN-S 10 305B A 0 0 0 0 S 1 0 0K: model, range, connection, pressure stage, heating or cooling, damping, drain, display, scale and electrical output. Special features include double eddy-current damping, a self-draining body, backflow stop, a special low-pressure-loss float, a flow controller, a display with pressure compensation against condensate build-up, and SIL conformity assessment by EXIDA.
Confirm before ordering: the gas or liquid data at operating conditions, the heat tracing need, the required wetted material (including NACE if relevant), the flange standard and the required certificate level, from 2.1 up to 3.1 and 3.2.
Where the KOBOLD BGN is used
- Hot liquid lines
- Hot gas lines
- High pressure lines
- Aggressive media
- Process plant skids
Selection checklist for the KOBOLD BGN
- Liquid or gas
- Flow range
- Process temperature
- Process pressure
- Wetted materials
- Connection type and size
- Switches or transmitter
- Heating or cooling jacket
Installation, commissioning and maintenance notes for the KOBOLD BGN
Mount the meter vertically with the flow going up and keep the pipe supported. Check the connections and set any switch points. Check the float, the pointer and the seals at regular intervals.
Requesting a quotation for the KOBOLD BGN
Please send the medium, the flow range, the pressure and the temperature. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.
KOBOLD BGN meter type
It is an all-metal variable area flow meter.
KOBOLD BGN media
It measures liquids and gases in pipes.
KOBOLD BGN float
A conical float rises in the meter tube with the flow.
KOBOLD BGN magnet coupling
A magnet transfers the float position to a follow magnet and pointer.
KOBOLD BGN display power
The display works without auxiliary power.
KOBOLD BGN scale
The scale reads volume or mass per unit time.
KOBOLD BGN temperature limit
The process temperature reaches 350 degrees C.
KOBOLD BGN versions
The versions are the BGN-S, BGN-P and BGN-H.
KOBOLD BGN stainless version
The BGN-S has a stainless steel tube.
KOBOLD BGN lined version
The BGN-P is stainless steel with a PTFE lining.
KOBOLD BGN lined version temperature
The BGN-P is rated up to 125 degrees C.
KOBOLD BGN Hastelloy version
The BGN-H has a Hastelloy C-22 tube.
KOBOLD BGN water range
Water ranges run from 0.5 to 5 l/h up to 13 000 to 130 000 l/h.
KOBOLD BGN air range
Air ranges run from 0.015 to 0.15 Nm3/h up to 240 to 2400 m3/h.
KOBOLD BGN size range
Connection sizes run from DN 15 to DN 150.
KOBOLD BGN connection types
Flange, NPT and screw pipe connections are available.
KOBOLD BGN ambient temperature
Ambient temperature runs from minus 40 to plus 80 degrees C.
KOBOLD BGN display housing
The display housing is aluminium or stainless steel.
KOBOLD BGN limit switches
Inductive switches or up to two micro changeover switches are optional.
KOBOLD BGN transmitter
A 4 to 20 mA transmitter with HART or FOUNDATION Fieldbus is optional.
KOBOLD BGN other options
Options include a counter module, damping and a self-draining body.
KOBOLD BGN heating and cooling
Heating or cooling is available as an option.
KOBOLD BGN flow controller
A flow controller is available as an option.
Flow meter records for the KOBOLD BGN
Record the float position, the medium and the date of each inspection.
Choosing the right KOBOLD BGN version
Choose the version from the medium, the temperature and the wetted material needed.
Documents and quotation
The KOBOLD BGN datasheet (edition 1/05-2026) is attached to this page. Browse our Flowmeters category for related instruments, or compare with the Tecfluid SC250 metal tube variable area flowmeter.
For a quotation, send the medium and its density and viscosity, flow range, pressure and temperature, connection, wetted material and any switch, HART or counter options.
Datasheets & Documents
- Datasheet KOBOLD BGN all-metal variable area flow meter datasheet Download
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About brand
KOBOLD Messring GmbH is a German instrumentation manufacturer based in Hofheim am Taunus, founded in 1980 by Klaus J. Kobold. It develops and manufactures instruments for monitoring, measuring and controlling flow, pressure, level and temperature, and the international KOBOLD group serves almost all sectors of industry.
Seven Star LLC is an independent supplier in Muscat. We list selected KOBOLD flow and level instruments for oil and gas, water, power and process plants in Oman and the GCC.
KOBOLD product series
Flow instruments include the TMU Coriolis mass flow meter from 60 to 80,000 kg/h, the KEC thermal mass flow meter for gases, the MIM all-metal magnetic inductive meter with IO-Link, the DRB turbine wheel meter, the DON-H high-pressure oval gear meter for 400 bar, the DOG-4 and DOG-6 oscillation meters for gases, the BGN all-metal variable area meter for up to 350 °C and the KAL calorimetric flow monitor for water.
Level instruments include the NGM guided wave radar transmitter, the NRE 80 GHz non-contact radar, the NMB magnetostrictive transmitter, the NWS tuning fork switch and the NBK-03 bypass magnetic level indicator for pressures up to PN 320.
Where KOBOLD instruments are used
Cooling water and lube oil monitoring on machines, chemical dosing and fuel metering, compressed air and gas consumption, tank and vessel level in process plants, and boiler and condensate systems. Many models carry ATEX or IECEx approvals and offer HART, Modbus or IO-Link.
Ordering KOBOLD instruments: what we need
Send the model code, the medium, measuring range, pressure and temperature, process connection and materials, output signal and any hazardous-area approval needed, and we will prepare a quotation from the KOBOLD datasheet.
Browse KOBOLD products by category: Flowmeters, Level Instrumentation.
Related products
Frequently Asked Questions
What flow ranges does the KOBOLD BGN cover?
From 0.5 to 5 l/h up to 13 000 to 130 000 l/h of water, and 0.015 to 0.15 Nm³/h up to 240 to 2400 m³/h of air.
How hot can the BGN measure?
Up to +350 °C with the high-temperature options, and +200 °C without electrical output as standard.
Does the BGN display need power?
No. A magnet drives the pointer, so local indication works without auxiliary power; power is needed for the transmitter and switches.
Which electrical options are offered?
NAMUR inductive switches, micro changeover switches, a 4 to 20 mA transmitter with HART or FOUNDATION Fieldbus, and a counter module.
What accuracy class is the BGN?
The datasheet states ±1.6 % of full scale for liquids and ±1.8 % for gases for the stainless and Hastelloy versions.
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