• Clamp-on measurement of operating and standard volume flow and mass flow of gases, bidirectional
• Independent of pipe material and process pressure: min. 45 to 100 psi on steel pipes, no minimum pressure on plastic pipes
• Measurement uncertainty of the measuring system ±0.3 % MV ±0.02 ft/s, with calibration certificate traceable to NIST
• Flow velocity from 0.03 to 115 ft/s, depending on pipe diameter
• 1 measuring channel, optional 2, with synchronized channel averaging
• Optional gas energy flow rate (DGM)
• 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 gas and utility gas flow in chemical and petrochemical plants
• Oil and gas: natural gas and fuel gas lines where cutting into the pipe is not an option
• Industrial gases such as nitrogen, oxygen, hydrogen, argon, and helium
• Consumption monitoring and balancing in manufacturing industries

• Type: gas ultrasonic flowmeter for permanent installation, clamp-on
• Measurement principle: transit time difference correlation principle
• Flow direction: bidirectional
• Flow velocity: 0.03 to 115 ft/s, depending on pipe diameter
• Repeatability: 0.15 % MV ±0.02 ft/s
• Fluid: all acoustically conductive gases, e.g., nitrogen, air, oxygen, hydrogen, argon, helium, ethylene, propane
• Process pressure: min. 45 to 100 psi on steel pipes; no minimum pressure for plastic pipes
• 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 to 2 % MV ±0.02 ft/s
• Temperature compensation: corresponding to the recommendations in ANSI/ASME MFC-5.1-2011
• Physical quantities: operating volumetric flow rate, standard volumetric flow rate, mass flow rate, flow velocity, optional: gas energy flow rate (DGM)
• Totalizer: volume, mass, optional: gas energy (DGM)
• 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
• 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

Gas flow is one of the hardest measurements to retrofit: inline meters need a cut pipe, flanges, and a shutdown, and every new joint on a gas line is a risk. The Flexim FLUXUS G731 measures from outside the pipe. The transducers clamp onto the wall, the line stays closed, and there is no pressure drop and no wetted part.

The G731 uses the transit time difference correlation principle and measures in both directions. It reports operating volume flow, standard volume flow, and mass flow, with optional gas energy flow rate (DGM). The reading is zero point stable and drift free, independent of pipe material and process pressure, with a minimum of 45 to 100 psi on steel pipes and no minimum pressure on plastic pipes. The measuring system reaches ±0.3 % MV ±0.02 ft/s, with a calibration certificate traceable to NIST.

The transmitter supports one or two measuring channels, a data logger for up to 800 000 values, and one process interface among Modbus RTU, BACnet MS/TP, HART, Profibus PA, FF H1, Modbus TCP, and BACnet IP. For Class I Div. 1 locations see the FLUXUS G831, for compressed air networks the FLUXUS G532 CA, and for liquids the FLUXUS F731.

The FLUXUS G731 is available through AV-TEK Consulting in North America. Flexim is part of Emerson. Uncertainty at the measuring point depends on the gas and the installation, so AV-TEK reviews your application with you before you order. Explore more clamp-on flow meters and the full Flexim range.