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Flexim F721

Contact Instrument Solutions


The Flexim Fluxus F721 offers non-intrusive flow measurement of virtually any kind of liquid, from the smallest tubing to the largest pipework, independent of the pressure inside the pipe and over a very large temperature range. For use in any industrial sector, the F721 is available with two different enclosure types: aluminium housing for standard applications and stainless steel housing for operation in highly corrosive environments. Both can be used in explosion hazard areas (ATEX, IECEX Zone 2, FM Class I, Div. 2, EAC TR TS, Inmetro).

Applications include: oil & gas, chemical, petrochemical, water & waste water, power generation, district energy, pharmaceuticals, semiconductor, food & beverage, mining & energy efficiency.


Ready for Industry

The Flexim Fluxus F721 comes with all common communication protocols: HART, Modbus, Foundation Fieldbus, Profibus PA and BACnet allow bidirectional field communication, parameterisation and online diagnostics. Further special configurations guarantee optimal customisation to the individual application. The F721 is also one step ahead in terms of user guidance and diagnostics. It can be easily parameterised via USB. Its ethernet connectivity provides additional bidirectional communication capabilities.


  • No process interruption for installation, no pipe works - maintenance-free (no need for frequent work in hazardous areas)
  • Certified for operation within hazardous areas (ATEX, IECEx Zone 2, FM Class I, Div. 2, EAC TR-TS, Inmetro)
  • Fast measuring dynamics (output of measurement data every 10ms) also capture highly pulsating flows
  • Reliable measurements of slurries or liquids with gaseous entrainments (>10% of total volume)
  • High operational safety with no risk of leaks
  • Independent of pipe material, diameter, wall thickness and internal pressure and temperature
  • Accurate and repeatable measurement readings - even at extremely low flow rates (high turndown ratio)
  • Highly cost efficient in comparison to wetted instrumentation
  • Every measurement system is pre-calibrated in-house (traceable to nationa standards) and delivered with a calibration certificate
  • Matched transducers, integrated temperature compensation (according to ANSI/ASME MFC-5.1-2011 regulations) and digital signal processing guarantee a high zero point and flow measurement stability
  • Permanent coupling with unique couplant pads, FlexSpring secured mounting fixtures guarantee durable contact pressure also on heavily vibrating pipes
  • Bidirectional communication as well as remote parameterisation and diagnostic capabilities


Flow channels 1 or 2

Operating temperature range of transmitter -40 to 60°C

Degree of protection (according to EN60529) Transmitter: IP66 Transducers: up to IP68

Available Hazardous Area Classification (optional) ATEX and IECEx Zone 2, FM Class I, Div. 2, Inmetro, EAC TR-TS

Outputs A variety of combinations are available from the following: current (0/4 mA to 20 mA), voltage, frequency, pulse, alarm Ethernet and USB ports for communication and parameterisation

Inputs Maximum 4, Available are: Temperature (PT 100 4-wire), current, voltage

Communication protocol Modbus, HART, Foundation Fieldbus, Profibus PA, BACNet

Media temperature -40 to 200 °C, -190 to 600 °C with high temperature wave injector mounting fixture

Pipe diameter range 6 mm to 6500 mm (no limitations on wall thickness and material)

Flow velocity range 0,01 to 25 m/s

Extremely low flows > 3l/h on 1/4 inch pipes (up to 1.5 inch diameter pipes)

Calibrated accuracy* at factory: ±0.35 % of reading, ±0,01 m/s
within the process: ±1.2 % of reading, ±0,01 m/s
within the process: ±0.5 % of reading, ±0,01 m/s (field calibrated)

*based on volume flow

Repeatability ±0.15% of reading, ±0,01 m/s

Support documents

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Flexim F721 fixed ultrasonic flow system data sheet.pdf Flexim F721 fixed ultrasonic flow system data sheet
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