2-Wire Dual Channel Transmitter/Analyzer FLXA21 Yokogawa FLXA21 Liquid Analyser (PH/ORP Transmitter)

1. Overview

• The FLXA21 is a 2‑wire, dual-channel liquid analyzer from Yokogawa.
• It supports two sensor inputs of the same type, enabling duplex measurement or redundancy.
• Compatible with a variety of detectors: pH/ORP, conductivity (contacting), inductive conductivity, and dissolved oxygen.
• Part of Yokogawa’s OpreX measurement family.

2. Key Features

3. Performance / Specs

Here are some key technical specifications from the manufacturer:

4. Advantages & Use Cases

Advantages:

• Reliability: With dual sensors, you get redundancy to avoid downtime.
• Maintenance Efficiency: Built-in diagnostics and calibration memory can reduce OPEX (operational cost).
• Flexibility: The modular design makes it easy to adapt to different measurement needs / parameters.
• Communication: Digital (HART) ensures better integration and remote diagnostics.

Typical Use Cases:

• Process control in water & wastewater treatment
• pH / ORP monitoring in chemical and petrochemical plants
• Conductivity measurement in industrial processes (including pure water, boiler water)
• Dissolved oxygen monitoring in bioreactors or water treatment plants

5. Limitations / Considerations

• Requires two sensors of the same type for dual-channel functionality — you cannot mix different sensor types.
• As a 2-wire device, the power supply is limited to 24 VDC loop, which may impose constraints in some installations.
• While self-diagnosis is helpful, some calibration and maintenance are still needed periodically.

6. Summary

The Yokogawa FLXA21 is a robust, modular, and redundant-capable 2-wire liquid analyzer. It’s well-suited for industrial environments where reliability, diagnostics, and long-term maintenance savings are important. It supports a broad range of sensor types (pH/ORP, conductivity, DO), and its self-diagnostics and dual-sensor capability make it a strong choice for critical process measurement applications.