• Flameproof/explosion proof housing for hazardous areas
• Certification: FM Class I Div. 1+2, ATEX/IECEx zone 1
• Up to two measuring channels, bidirectional volume and mass flow
• Integrated disturbance correction for more precise measurement at unfavorable measuring points
• Automatic NoiseTrek selection for liquids with high gaseous or solid content
• Measurement uncertainty of the measuring system ±0.3 % MV ±0.02 ft/s, with calibration certificate traceable to NIST
• Intrinsically safe process inputs for external pressure and temperature sensors (ATEX/IECEx versions)
• HART, Profibus PA, FF H1, Modbus RTU/RS485, BACnet MS/TP (max. 1 option, depending on version)
• Cast aluminum housing with heavy-duty C5 coating or stainless steel 316/316L

• Crude oil, condensate, and produced water lines in upstream and midstream
• Refinery and petrochemical process liquids in classified areas
• Chemical plants where cutting into a line means a hot work permit and downtime
• Verification of installed meters on hazardous area lines

• Type: ultrasonic flowmeter for liquids for permanent installation in hazardous areas, 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: measuring range 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
• Totalizer: volume, mass
• Number of measuring channels: 1, optional: 2
• Power supply (FM Class I Div. 1 version): 100 to 240 V/50 to 60 Hz or 20 to 32 V DC
• Power consumption (FM Class I Div. 1 version): <8 W
• Response time: 1 s (1 channel), option: 0.02 s
• Housing material (FM version): cast aluminum EN AC 44200 mod, special heavy-duty coating (C5 according to EN ISO 12944)
• Degree of protection (FM version): TYPE 4X/IP66
• Weight: aluminum housing 14.3 lb, stainless steel housing 34.4 lb
• Fixation: wall mounting, 2" pipe mounting
• Display: 128 x 64 pixels, backlight
• Service interface: USB
• Process interfaces (FM version, max. 1 option): Modbus RTU/RS485, HART, Profibus PA, FF H1, BACnet MS/TP
• Data logger: max. 800 000 measured values
• Hazardous area, FM: Cl. I Div. 1, GP. A, B, C, D / T6 (for Group A, conduit seal of connection compartment is required within 18 inches) or Cl. I Div. 1, GP. B, C, D / T6, depending on version; Cl. II, Div. 1, GP. E, F, G / T6; Cl. III, Div. 1 / T6; Cl. I, II, III, Div. 2, GP A, B, C, D, F, G / T4A; Ta = -40°C to +60°C
• Hazardous area, ATEX/IECEx: zone 1 (Ex db eb IIC T6 Gb, Ex tb IIIC T100 °C Db; versions with intrinsically safe inputs/outputs Ex ia)

In a classified area, every inline meter installation means a line break, a hot work permit, and a new joint that has to stay tight for years. The Flexim FLUXUS F831 is a clamp-on liquid flowmeter built for exactly those locations: the transducers mount on the outside of the pipe and the transmitter sits in a flameproof/explosion proof housing, certified FM Class I Div. 1 and Div. 2 or ATEX/IECEx zone 1.

The F831 measures volume and mass flow in both directions on the transit time difference correlation principle, with automatic NoiseTrek selection when the liquid carries gas or solids. Integrated disturbance correction improves the result at unfavorable measuring points, where straight runs are short. The measuring system reaches ±0.3 % MV ±0.02 ft/s, with a calibration certificate traceable to NIST.

The transmitter supports up to two measuring channels and connects to HART, Profibus PA, FF H1, Modbus RTU/RS485, or BACnet MS/TP depending on the version. ATEX/IECEx versions offer intrinsically safe process inputs for external pressure and temperature sensors. For gas in hazardous areas see the FLUXUS G831, and for portable checks the FLUXUS F608.

The FLUXUS F831 is available through AV-TEK Consulting in North America. Flexim is part of Emerson. Certification, housing, and interface depend on your area classification, and AV-TEK helps you specify the right version for your site. Explore more clamp-on flow meters and the full Flexim range.