• Clamp-on volume and mass flow measurement of liquids, bidirectional
• Transit time difference correlation principle with automatic NoiseTrek selection for high gaseous or solid content
• Measurement uncertainty of the measuring system ±0.3 % MV ±0.02 ft/s, with calibration certificate traceable to NIST
• Repeatability 0.15 % MV ±0.02 ft/s
• 1 measuring channel, optional 2, with synchronized channel averaging
• Temperature compensation according to ANSI/ASME MFC-5.1-2011
• Thermal energy rate when Pt100/Pt1000 temperature inputs are installed
• Data logger for up to 800 000 measured values
• Aluminum or stainless steel 316L housing, IP66, with ATEX/IECEx and FM Class I Div. 2 versions

• Process liquid flow in chemical and petrochemical plants
• Oil and gas liquid lines where cutting into the pipe means downtime and a new leak point
• Water and wastewater flow monitoring and balancing
• Pharmaceutical and semiconductor processes, with no contact with the fluid
• Building technology and energy management, including thermal energy with temperature inputs
• Mining and manufacturing industries

• Type: permanently installed ultrasonic flowmeter for liquids, clamp-on
• Measurement principle: transit time difference correlation principle, automatic NoiseTrek selection for measurements with high gaseous or solid content
• Flow direction: bidirectional
• Flow velocity: 0.03 to 82 ft/s (max. value depending on the application)
• Repeatability: 0.15 % MV ±0.02 ft/s
• Fluid: all acoustically conductive liquids with < 10 % gaseous or solid content in volume (transit time difference principle)
• Measurement uncertainty of the measuring system: ±0.3 % MV ±0.02 ft/s, includes calibration certificate traceable to NIST (with aperture calibration of the transducers)
• Measurement uncertainty at the measuring point: ±1 % MV ±0.02 ft/s (for transit time difference principle and reference conditions)
• Temperature compensation: corresponding to the recommendations in ANSI/ASME MFC-5.1-2011
• Physical quantities: volumetric flow rate, mass flow rate, flow velocity, thermal energy rate (if temperature inputs are installed)
• Totalizer: volume, mass, optional: thermal energy
• Number of measuring channels: 1, optional: 2
• Power supply: 100 to 240 V ±10 %/50 to 60 Hz or 11 to 32 V DC
• Power consumption: < 15 W
• Response time: 1 s (1 channel), option: 0.02 s
• Housing material: aluminum, powder coated or stainless steel 316L
• Degree of protection: IP66
• Weight: aluminum housing 9.9 lb, stainless steel housing 12.8 lb
• Fixation: wall mounting, optional: 2" pipe mounting
• Ambient temperature (FM Class I Div. 2 version): -40 to +140 °F (< -4 °F without operation of the display)
• Display: 240 x 128 pixels, backlight
• Outputs: switchable current output 4 to 20 mA (NAMUR NE 43), frequency, binary and pulse output (open collector); current inputs and outputs max. 4, on request
• Inputs: temperature input Pt100/Pt1000, 4-wire, -238 to +1040 °F; switchable current input 0 to 20 mA
• Service interfaces: USB, LAN
• Process interfaces (max. 1 option): Modbus RTU, BACnet MS/TP, HART, Profibus PA, FF H1, Modbus TCP, BACnet IP
• Data logger: max. 800 000 measured values
• Hazardous area, FM: Cl. I,II,III/Div. 2 / GP. A, B, C, D, F, G / T5 (FM23US0036, FM23CA0026)
• Hazardous area, ATEX/IECEx: II3G Ex ec IIC T4 Gc, II2D Ex tb IIIC T135 °C Db
• Ordinary locations: optional FM25US0185, FM25CA0073

Measuring liquid flow usually means opening the line: a shutdown, a hot work permit, a spool piece, and one more joint that can leak. The Flexim FLUXUS F731 avoids all of that. Its ultrasonic transducers clamp onto the outside of the pipe, so the meter goes onto a running line and never touches the fluid.

The F731 works on the transit time difference correlation principle and switches automatically to NoiseTrek when the liquid carries a high gaseous or solid content. It measures volume and mass flow in both directions, and the reading is zero point stable and drift free, independent of pipe material, process pressure, process temperature, and fluid. The measuring system reaches ±0.3 % MV ±0.02 ft/s, with a calibration certificate traceable to NIST.

One transmitter handles one or two measuring channels, with synchronized channel averaging on two paths. Add Pt100/Pt1000 temperature inputs and the same meter reports thermal energy rate. Outputs include 4 to 20 mA, frequency, pulse, and binary, with one process interface among Modbus RTU, BACnet MS/TP, HART, Profibus PA, FF H1, Modbus TCP, and BACnet IP. For gas lines see the FLUXUS G731, for Class I Div. 1 locations the FLUXUS F831, and for temporary checks the portable FLUXUS F608.

The FLUXUS F731 is available through AV-TEK Consulting in North America. Flexim is part of Emerson. AV-TEK helps you match transmitter version, transducers, and outputs to your pipe size, wall, and fluid temperature. Explore more clamp-on flow meters and the full Flexim range.