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Brand: Tokyo Keiso
Tokyo Keiso FM4000 MAG GAUGE Magnetic Metal Tube Level Gauge
Description
Metal-tube magnetic level gauge for high pressure and temperature duty
The Tokyo Keiso FM4000 MAG GAUGE is a metal-tube magnetic level gauge, an improved successor to Tokyo Keiso’s long-running FM-1000 series. A float with an internal magnet rides in a metal chamber, and plastic magnet flappers in an external indicator rotate as the float passes. The flappers change colour, black for no liquid and yellow with red marks every 100 mm, so the level can be read from a distance without glass that can blur, smudge or break.
The pressure-containing and wetted parts are all metal. The series covers liquid temperatures from -196 to +400 °C and pressures up to 40 MPa (not in combination at the maxima), liquid density down to 0.39 g/cm3 and interface measurement where density difference is 0.2 g/cm3 or more. One gauge can provide local indication, alarm switches and a 4-20 mA transmitter.
Technical specifications
Data from Tokyo Keiso technical guidance TG-L2176-E08 (9th edition, June 2026).
| Parameter | Specification |
|---|---|
| Manufacturer / model | Tokyo Keiso MAG GAUGE FM4000 (models FM4100 to FM4800) |
| Chamber size | FM4100 40A; FM4200, 4300, 4500, 4600 50A welded; FM4400, 4700 50A seamless; FM4800 65A seamless |
| Maximum pressure | FM4100/4200/4500 2 MPa; FM4300/4600 3 MPa; FM4400/4700 13 MPa; FM4800 40 MPa |
| Temperature range | FM4100, 4500, 4700: -196 to +400 °C; FM4600: -196 to +225 °C; FM4200, 4300, 4400, 4800: -10 to +120 °C |
| Minimum density | 0.39 to 0.84 g/cm3 depending on model (FM4800 0.84, FM4400 0.52, FM4700 0.57, FM4100 0.41) |
| Viscosity | Up to 25 mPa.s (FM4100); up to 600 mPa.s (others); no sticking or freezing liquids |
| Measurement length | 250 mm minimum to 4,800 mm maximum |
| Indication | Colour flapper, 10 mm pitch; accuracy 15 mm |
| Process connection | Flanges JIS 10K/20K, ASME 150/300, JPI 150/300 and others; standard 25A (1 in), also 15A, 20A, 40A, 50A |
| Vent / drain | R1/2 plug standard; NPT1/2 plug, Rc1/2 ball valve and others |
| Chamber materials | SUS304, SUS316, SUS316L and special materials; float SUS316L, titanium or Ti-6Al-4V |
| Indicator | Aluminium alloy housing; acrylic window (glass above 350 °C) |
| Alarm switch (option) | Reed SPST; 10 VA/W, 200 V DC 0.5 A, 140 V AC 0.35 A; repeatability 15 mm; IECEx/ATEX/JPN types |
| Transmitter (option) | Magnetostrictive; 4-20 mA two-wire with HART Rev.7; 12 to 40 V DC; accuracy (0.1% F.S. or 2 mm, whichever larger) plus 3 mm; IECEx Ex db ia IIB T4 Gb, ATEX, JPN, China |
Choosing among the eight models
The model decides pressure class, chamber construction and temperature band, and the catalogue includes a selection matrix of temperature against pressure. Up to 120 °C the options run from 2 MPa (FM4100, FM4200) through 3 MPa (FM4300) and 13 MPa (FM4400) to 40 MPa (FM4800); FM4500, FM4600 and FM4700 extend the temperature to 225 °C or 400 °C. The catalogue states that the maximum pressure and temperature cannot be combined, so check the exact combination on the model code pages before ordering.
Gaskets for the chamber bottom flange are matched to temperature, from sheet gasket (-50 to +150 °C) through spiral wound (to +300 °C) to graphite spiral wound (to +400 °C) and octagonal ring joint. Bolting changes below 0 °C.
Alarms, transmitters and special designs
Alarm switches (upper and lower limit, minimum alarm interval 250 mm) and the magnetostrictive 4-20 mA transmitter are added with extra code positions. Gauges can be made to customer specification for connection size, measuring range, density and vent and drain design, and Tokyo Keiso asks for a specification confirmation sheet when a special specification, alarm switch or magnetostrictive sensor is requested.
Documents and quotation
The Tokyo Keiso FM4000 catalogue is attached to this page as a PDF with the model code tables, dimensions and the alarm and transmitter specifications. Send us the vessel data, liquid, density, temperature, pressure and approvals required, and we will quote against the catalogue codes. Seven Star LLC is an independent supplier in Muscat; price and lead time are confirmed per RFQ. Related range: level instrumentation and the ABB KM26 magnetic level gauge.
Datasheets & Documents
- Catalog Tokyo Keiso MAG GAUGE FM4000 Metal Tube Level Gauge catalogue (TG-L2176-E08, 9th edition Jun 2026) Download
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About brand
Tokyo Keiso is a Japanese manufacturer of flow and level instruments, founded in Tokyo in 1954 as Japan's first maker of variable-area flowmeters. It now builds ultrasonic, Coriolis, electromagnetic and variable-area flowmeters plus level gauges, and set up a production subsidiary in Korea in 2012 for non-contact ultrasonic flowmeters.
Seven Star LLC is an independent supplier in Muscat. We list Tokyo Keiso models from the maker's published technical documents for water, oil and gas, power and chemical plants in Oman and the GCC.
Tokyo Keiso company profile
| Founded | 1954, Tokyo, Japan |
|---|---|
| First products | Variable-area flowmeters, a first for a Japanese manufacturer |
| Headquarters | Tokyo, Japan |
| Leadership | Ryoichi Sugi, President |
| Product families | SONICMAX inline and clamp-on ultrasonic flowmeters (UL3400, UL6300, UL350), MASSMAX Coriolis mass flowmeters, electromagnetic and variable-area flowmeters, float and magnetic level gauges |
Milestones
- 1954: Tokyo Keiso is founded as Japan's first variable-area flowmeter maker.
- 2012: TK Flow Engineering is set up in Korea for ultrasonic flowmeter production.
Tokyo Keiso product series
Ultrasonic flowmeters include the UL350 and SONICMAX UL6300 V2 clamp-on meters and the SONICMAX UL3400 three-beam inline meter. Other flowmeters include the MASSMAX 2400R Coriolis mass flowmeter, the VFM4200 SWIRLMAX vortex meter, the MAGMAX EGM2100C compact electromagnetic flowmeter, the TH series thermal gas flowmeters and the VC series V-Cone differential pressure flowmeter.
Level instruments include the TLR7500 80 GHz microwave level meter, the TGF7200 guided radar, the FM4000 MAG GAUGE magnetic metal tube level gauge and the FW-9000NN servo balance tank gauge for storage tanks.
Where Tokyo Keiso instruments are used
Water and wastewater networks, chemical and petrochemical plants, oil and gas facilities, power stations and tank terminals, with outputs such as 4-20 mA, pulse and digital communication for connection to control systems.
Tokyo Keiso products we list
Ordering Tokyo Keiso instruments: what we need
Send the fluid, line size, flow or level range, pressure and temperature, process connection and materials, output signals and any hazardous-area option. Where a catalogue is older or an option is still in preparation, we say so on the product page.
Facts checked against Tokyo Keiso company profiles and a 2022 interview with its president, October 2026.
Browse Tokyo Keiso products by category: Flowmeters, Level Instrumentation.
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Frequently Asked Questions
How does the FM4000 show level?
A magnetic float turns colour flappers in an external indicator, so no glass window is in the pressure boundary.
What temperature and pressure can it handle?
Liquid temperature from -196 to +400 °C and pressure up to 40 MPa, depending on model; the maximum values cannot be combined.
Can it send a signal to a control system?
Yes. An optional magnetostrictive transmitter gives 4-20 mA with HART Rev.7, and reed-type alarm switches are available.
How long can the measuring length be?
From 250 mm up to 4,800 mm.
Can it measure an interface?
Yes, when the density difference is 0.2 g/cm3 or more and the density sum is 1.2 g/cm3 or higher.
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