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YOKOGAWA NFLR121-S51 S1 RS-422/RS-485
Product Introduction:
The NFLR121-S51 S1 RS-422/RS-485 is a large-bore electromagnetic flowmeter from Yokogawa’s ADMAG AXF (NFLR) series, configured for high-accuracy flow measurement of conductive liquids with RS-422/RS-485 serial communication. The “S51” denotes a specific size and lining/electrode configuration, “S1” denotes the sensor specification (PFA liner, SUS316L electrodes), and the communication option provides direct digital communication for integration with SCADA, DCS, or flow computers.
Detailed content
Measurement Principle:
Based on Faraday’s Law of Electromagnetic Induction. A magnetic field is generated across the flow tube by excitation coils. The voltage induced across the electrodes by the moving conductive fluid is proportional to the average flow velocity. The NFLR series uses dual-frequency rectangular wave excitation to eliminate noise from fluid conductivity variations and electrode coating effects.
Technical Specifications:
| Parameter | Specification |
|---|---|
| Model | NFLR121-S51 S1 RS-422/RS-485 |
| Pipe Size (S51) | DN300 to DN1200 (12″ to 48″) (verify exact size per S51 code) |
| Accuracy | ±0.5% of reading |
| Repeatability | ±0.2% of reading |
| Output | 4–20 mA DC + RS-422/RS-485 (Modbus RTU) |
| Communication | RS-422 (full-duplex) / RS-485 (half-duplex, Modbus RTU) |
| Liner (S1) | PFA (Perfluoroalkoxy) |
| Electrodes (S1) | SUS316L Stainless Steel (standard); Hastelloy C, Titanium, Tantalum optional |
| Fluid Conductivity | ≥ 5 μS/cm |
| Process Temperature (PFA) | -20°C to +180°C (-4°F to +356°F) |
| Process Pressure | Up to 1.0 MPa (145 psi) for DN300+; up to 1.6 MPa for smaller sizes |
| Protection Class | IP67 / IP68 (submersible) |
| Flange Standard | JIS 10K/20K, ANSI 150#/300#, DIN PN10/16, BS 10#/16# |
| Power Supply | 100–240 V AC, 50/60 Hz or 24 V DC |
| Communication Protocol | Modbus RTU over RS-422/RS-485 (9600/19200/38400 bps) |
| Approvals | ATEX, IECEx, FM, CSA, SIL2, JIS, JWWA, WRAS |
Structural Features:
- Flanged installation for large bore sizes (DN300 and above)
- PFA liner (S1) — chemically inert, suitable for aggressive chemicals
- SUS316L electrodes — general-purpose corrosion resistance
- IP67/IP68 rated — suitable for buried or submerged installations
- Integral converter with LCD display and keypad
- RS-422/RS-485 communication port — direct connection to flow computers or RTUs
Performance Parameters:
| Parameter | Value |
|---|---|
| Flow Velocity Range | 0.1 to 10 m/s |
| Minimum Conductivity | ≥ 5 μS/cm |
| Response Time | ≤ 1 second (95%) |
| Zero Stability | ±0.1% of span per year |
| Electrode Noise | ≤ ±0.5% of span (with dual-frequency excitation) |
| Display | 128 × 64 pixel LCD with backlight |
| Data Logging | Flow total, totalizer, alarm events |
| Alarm Outputs | 2 relay outputs (optional) |
| Ambient Temperature | -20°C to +60°C |
Key Advantages:
- Large bore capability (up to DN1200) — ideal for water mains, cooling water, and bulk chemical transfer
- PFA liner (S1) — excellent chemical resistance for aggressive process fluids
- RS-422/RS-485 communication — direct Modbus connection to flow computers, RTUs, and SCADA systems without protocol converters
- Dual-frequency excitation — stable measurement even with coating or varying conductivity
- IP68 submersible — suitable for underground vaults and sumps
- JWWA and WRAS approved — certified for potable water service
Applicable Industries:
- Municipal Water Supply (Large Mains)
- Industrial Cooling Water Systems
- Chemical Processing (Bulk Transfer)
- Mining Slurry and Tailings
- Power Plant Cooling Water
- Fire Protection Water Mains
- Pulp and Paper (White Water)
Installation Requirements:
- Install in full-pipe conditions only — the meter must be completely filled at all times
- Maintain minimum 5D upstream and 3D downstream straight pipe (D = pipe diameter)
- For flanged meters: use gaskets that do not protrude into the bore; bolt evenly in a star pattern
- Ground the flowmeter and both flanges to the pipeline ground system
- Use shielded twisted-pair cable for RS-422/RS-485 — maximum cable length: 1200 m (RS-485 at 9600 bps)
- Set the Modbus address and baud rate via the front panel keypad before connecting to the host system
- Install a surge protector on the communication line if the cable runs near high-voltage equipment
Usage Precautions:
- Never run the meter with an empty tube — PFA liner can be damaged by air exposure under pressure
- Verify the fluid conductivity exceeds 5 μS/cm — low-conductivity fluids cause unstable readings
- Clean PFA electrodes annually in fouling applications — use soft brush and distilled water
- Do not exceed +180°C process temperature for PFA liner — PFA softens above this temperature
- Terminate RS-485 bus with 120 Ω resistor at both ends of the bus
- Do not mix RS-422 and RS-485 devices on the same bus without proper conversion
- Perform zero calibration with the pipe full of stationary process fluid
