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Brand: Tokyo Keiso
Tokyo Keiso UL350 Clamp-On Ultrasonic Flowmeter
Description
Non-invasive flow measurement on pipes from 25 mm to 1000 mm
The Tokyo Keiso UL350 is a clamp-on, time-of-flight ultrasonic flowmeter for liquids. Its sensors are strapped to the outside of an existing metallic or plastic pipe, so the fluid is never touched: there is no pipe cut, no pressure loss, no corrosion of a wetted sensor and no risk of metal ions or solids entering the line. The catalogue states a nominal pipe range of 25 mm to 1000 mm.
The measurement works by sending ultrasound alternately downstream and upstream across the pipe at a known angle. The difference between the two transit times gives the average velocity, and the converter multiplies it by the pipe cross-section. Tokyo Keiso adds a digital signal processor and AD converters to speed up measurement and to improve resistance to bubbles, and the instrument has no moving parts.
Technical specifications
Values are taken from the Tokyo Keiso technical guidance TG-F2334-E01 (2nd edition, May 2026).
| Parameter | Specification |
|---|---|
| Manufacturer / model | Tokyo Keiso UL350 (converter UFC350, sensors UFS330 / UFS350) |
| Measuring method | Ultrasonic time-of-flight, clamp-on; reflex mode (V path) or diagonal mode (Z path) |
| Measurable fluid | Liquids in which ultrasonic waves propagate |
| Pipe size (nominal diameter) | 25 mm minimum to 1000 mm maximum; metallic and plastic piping |
| Fluid temperature | Up to 90 °C (pipe surface temperature) |
| Sound velocity / kinematic viscosity | 1,000 to 2,500 m/s; 0.30 to 40.00 mm2/s |
| Flow velocity range | 0 to 10 m/s |
| Accuracy | 2% of reading at 1 m/s or more and Reynolds number 10,000 or more; ±2 cm/s below 1 m/s |
| Display | 16-character, 2-line backlit LCD; 3 status LEDs |
| Outputs | 4-20 mA DC (load 500 ohm or less); open-collector pulse (30 V DC, 50 mA); 3 status outputs; RS-485 Modbus |
| Status outputs | Hold; empty pipe detection; forward or backward flow |
| Power supply | 100 to 230 V AC, 50/60 Hz (85 to 264 V AC acceptable); 12 VA or less |
| Enclosure | Converter and sensor IP65 (sensor with BNC connectors coupled) |
| Materials | Sensor housing heat-resisting ABS; sensor rail aluminium; converter housing heat-resisting ABS |
| Ambient temperature | Sensor -10 to 70 °C; converter -20 to 50 °C, 10 to 90% RH |
| Sensor cable | 10 m standard; options up to 60 m (double-shielded) |
| Sample flow range | DN25: 0.684 to 22.80 m3/h; DN100: 9.948 to 331.6 m3/h; DN500: 209.5 to 6,984 m3/h |
Choosing sensors and checking the application
The sensor type depends on pipe material and size. Sensor A (2 MHz, UFS330) and sensor B (1 MHz, UFS350) are combined with a short or long sensor rail, and the catalogue includes a selection table by pipe material (SGP, stainless steel, PVC and polyethylene, PP, PVDF and polyethylene-lined pipe) and by nominal size. Notes in the catalogue advise V-path mounting for pipes up to about 400 mm and a long rail pair when the pipe size is unknown or above 100 mm.
Tokyo Keiso lists conditions where measurement may not be possible and recommends contacting the manufacturer first: liquids with many bubbles (over 2% as a guide) or solids (over 5 vol% as a guide), low Reynolds numbers below 10,000, liquids other than water such as lean chemicals, oils and waste water, strongly attenuating liquids such as acetic acid (not above 50%), rusty or scaled pipe interiors, galvanised SGPW pipe, lined pipe and steel pipe above 500 mm. Pipes of schedule 80 or heavier need prior consultation. The guide also tabulates the straight run needed upstream and downstream of bends, tees, reducers, valves and pumps.
Signals and communication
The analog, pulse and status outputs support simulation for loop checks, and RS-485 serial output with the Modbus protocol allows several units on one multi-drop line (slave addresses 1 to 31, up to 19,200 baud, 1.2 km total length). Damping is adjustable from 0 to 100 s and low-flow cut-off from 0 to 30% of maximum.
Documents and quotation
The Tokyo Keiso catalogue for the UL350 is attached to this page as a PDF so you can check the selection tables and model code before ordering. Please send us the pipe material, outside diameter, wall thickness, liquid, temperature and the signals you need, and we will prepare a quotation. Seven Star LLC is an independent supplier in Muscat; delivery time and price are confirmed per enquiry. See also our flowmeter range and the pFlow D118 clamp-on ultrasonic flow meter.
Datasheets & Documents
- Catalog Tokyo Keiso UL350 Clamp-on Ultrasonic Flowmeter catalogue (TG-F2334-E01, 2nd edition May 2026) Download
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About brand
Tokyo Keiso flowmeters and level instruments
Tokyo Keiso is a Japanese instrumentation manufacturer based in Tokyo, founded in 1954. Its range centres on flowmeters and level gauges for process industries, including clamp-on and inline ultrasonic flowmeters, Coriolis mass flowmeters, V-Cone differential pressure meters, electromagnetic meters, radar level transmitters and float-type tank gauges.
Typical applications
The catalogues describe use in water and wastewater, chemicals, oil and gas, power and general plant services, with outputs such as 4-20 mA, pulse and digital communication for connection to control systems. Catalogue sheets list measuring range, accuracy, process connections, materials and hazardous-arean options for each model, which makes it straightforward to compare candidates before requesting a price. Where a catalogue is older or an option is still in preparation, we say so on the product page.
Sourcing Tokyo Keiso products in Oman
Seven Star LLC lists Tokyo Keiso models from the maker's published technical guidance and prepares quotations on request. Send the fluid, line size, temperature and signals needed and we will check them against the catalogue.
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Frequently Asked Questions
Does the UL350 need a pipe cut?
No. The sensors clamp onto the outside of the existing pipe, so no part touches the liquid and the line does not need to be opened.
What pipe sizes does the UL350 cover?
The catalogue gives 25 mm to 1000 mm nominal diameter for metallic and plastic pipes, using sensor A or B and short or long rails.
Which outputs does it provide?
4-20 mA DC, an open-collector pulse output, three status outputs and RS-485 with Modbus.
What is the stated accuracy?
2% of reading at 1 m/s or more with Reynolds number 10,000 or more; below 1 m/s the error is 2 cm/s.
Which liquids are difficult?
Liquids with many bubbles or solids, low Reynolds number flow and strongly attenuating liquids such as high-concentration acetic acid.
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