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YOKOGAWA NFAR181-S05

Product Introduction:
The NFAR181-S05 is a 2-wire electromagnetic flowmeter designed for continuous measurement of conductive liquid flow rates in industrial process environments. It operates on Faraday’s Law of Electromagnetic Induction, generating a voltage proportional to the flow velocity of the conductive fluid passing through the magnetic field. The 2-wire configuration simplifies wiring by combining power supply and signal output on a single pair of cables, delivering a 4–20 mA DC output signal.

Detailed content

Technical Specifications:

  • Nominal Diameter: DN80 (3 inches)
  • Flow Rate Range: 0.32 to 32 m³/h (water equivalent)
  • Accuracy: ±0.5% of reading
  • Repeatability: ±0.2%
  • Output Signal: 4–20 mA DC (2-wire system)
  • Power Supply: 24 V DC (operating range: 18–36 V DC)
  • Liner MaterialPFA (Perfluoroalkoxy) — S05 designation
  • Electrode Material: SUS316L Stainless Steel — S05 designation
  • Maximum Fluid Temperature: 150 °C (PFA liner)
  • Process Connection: Flanged (JIS 10K / ANSI 150)
  • Protection ClassIP67 / IP68 (NEMA 4X)
  • Ambient Temperature: -20 °C to +60 °C
  • Communication Protocol: HART 7 Protocol
  • Approvals: ATEX, IECEx, FM, CSA, SIL (when used with safety systems)

Functional Features:

  • 2-wire loop-powered operation eliminates need for separate power cabling
  • Empty pipe detection and electrode leakage diagnosis
  • Programmable damping time (0.1 to 100 seconds)
  • Bidirectional flow measurement capability
  • Low flow cut-off function configurable
  • Self-diagnostics with alarm output

Performance Parameters:

  • Measurement Principle: Faraday’s Law of Electromagnetic Induction
  • Fluid Conductivity Requirement: ≥ 5 μS/cm
  • Pressure Rating: 1.6 MPa (232 psi)
  • Response Time: ≤ 1 second (63% of step change)
  • Zero Stability: ±0.1% of span over 1 year

Material Composition:

  • Body/Tube: Carbon Steel with PFA lining
  • LinerPFA (Perfluoroalkoxy) — chemical resistant, suitable for corrosive media
  • ElectrodesSUS316L Stainless Steel — corrosion-resistant, suitable for general-purpose and mildly corrosive fluids
  • Flange: Carbon Steel with epoxy coating
  • Housing: Aluminum alloy with powder-coated finish

Structural Features:

  • Compact integral-type transmitter design
  • Flanged process connection for DN80 pipelines
  • Splash-proof terminal housing with cable gland entry (M20 × 1.5)
  • Wall-mount or in-line installation capable

Working Principle:
When a conductive fluid flows through a magnetic field generated by coils inside the flow tube, an electromotive force (EMF) is induced across the fluid perpendicular to both the flow direction and the magnetic field. This induced voltage is directly proportional to the average flow velocity. Electrodes mounted flush with the liner wall detect this voltage, and the transmitter electronics convert it into a standardized 4–20 mA output signal representing the volumetric flow rate.

Advantages & Highlights:

  • 2-wire system drastically reduces installation and wiring costs
  • PFA liner provides excellent chemical resistance against acids, alkalis, and solvents
  • SUS316L electrodes ensure long service life in aggressive media
  • HART communication enables remote configuration and diagnostics without process shutdown
  • No moving parts — zero pressure drop, minimal maintenance

Applicable Industries:

  • Water and Wastewater Treatment
  • Chemical and Petrochemical Processing
  • Pharmaceutical Manufacturing
  • Food and Beverage Production
  • Pulp and Paper Industry
  • Mining and Mineral Processing
  • Power Generation (cooling water, condensate)

Installation Requirements:

  • Install in a section of pipe with a minimum of 10D upstream and 5D downstream straight pipe run (D = pipe diameter)
  • Ensure the flow tube is always fully filled with liquid (no air pockets)
  • Mount vertically or horizontally; for vertical installation, flow direction must be upward
  • Ground the transmitter and use shielded cable; grounding resistance must be ≤ 100 Ω
  • Avoid installation near strong electromagnetic interference sources (large motors, VFDs, welders)

Usage Precautions:

  • The fluid must have a minimum conductivity of 5 μS/cm; non-conductive fluids (pure water, oils, gases) cannot be measured
  • Do not exceed the maximum rated pressure of 1.6 MPa
  • PFA liner maximum temperature is 150 °C — do not exceed
  • Periodically inspect electrode surfaces for coating or fouling
  • Perform zero calibration after initial installation and after any maintenance

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