HORIBA HR-400 Residual Chlorine Online Analyzer

Overview

The HORIBA HR-400 Residual Chlorine Online Analyzer is a robust, industrial-grade electrochemical analyzer engineered for continuous, real-time monitoring of free chlorine (Cl₂) and total chlorine concentrations in potable water distribution systems, municipal drinking water treatment plants, and recreational aquatic facilities—including swimming pools and splash pads. It operates on the amperometric principle, utilizing a membrane-covered, three-electrode sensor system that selectively detects hypochlorous acid (HOCl) and hypochlorite ion (OCl⁻) in aqueous solution under controlled pH and temperature conditions. The analyzer delivers stable, low-drift measurements with minimal calibration frequency, supporting compliance-driven operational continuity in environments where regulatory adherence to WHO, EPA Method 334.0, and ISO 7393-2 is mandatory.

Key Features

• Amperometric detection with integrated temperature compensation (PT1000 sensor) and automatic pH correction (when paired with optional pH module)
• Zero-maintenance electrochemical sensor featuring a solid-state reference electrode and chlorine-selective working electrode—eliminating liquid-filled electrolyte chambers and reducing drift
• Modular transmitter design supporting 4–20 mA analog output, Modbus RTU over RS-485, and optional Ethernet/IP or PROFIBUS DP connectivity
• IP66-rated enclosure with corrosion-resistant stainless steel front panel and internal humidity control for outdoor or wet-location installation
• Auto-ranging measurement capability from 0.01 to 5.00 mg/L Cl₂ with configurable alarm thresholds and event logging
• Self-diagnostic firmware with sensor health monitoring, signal noise analysis, and predictive maintenance alerts via status LED and digital interface

Sample Compatibility & Compliance

The HR-400 is validated for use in clarified, low-turbidity water matrices (NTU < 1.0) with conductivity between 50–2000 µS/cm and pH 5.5–8.5. It is not recommended for raw surface water, seawater, or high-organic-load effluents without pretreatment. The analyzer complies with IEC 61000-6-2 (EMC immunity), IEC 61000-6-4 (EMC emission), and meets CE marking requirements for instrumentation in water utility applications. When deployed in regulated pharmaceutical or food & beverage facilities, it supports audit-ready documentation per FDA 21 CFR Part 11 when integrated with HORIBA’s optional data management software (Liquiline Suite).

Software & Data Management

The HR-400 interfaces seamlessly with HORIBA’s Liquiline CM44 transmitter platform and Liquiline Suite PC software for configuration, calibration history tracking, and trend visualization. All calibration events, sensor diagnostics, and measurement anomalies are time-stamped and stored locally (up to 30 days of 1-minute interval data). Exportable CSV logs include metadata such as ambient temperature, flow rate (if external flow switch is connected), and operator ID—enabling traceability aligned with GLP and GMP quality systems. Remote access is supported via secure HTTPS-enabled web interface or OPC UA server integration for SCADA and MES platforms.

Applications

• Real-time residual chlorine verification at water treatment plant clearwells and distribution system entry points
• Automated dosing control feedback for sodium hypochlorite or chlorine gas feed systems
• Continuous compliance monitoring for NSF/ANSI Standard 50-certified pool and spa management systems
• Post-disinfection validation in hospital sterilization rinse loops and pharmaceutical purified water (PW) systems
• Troubleshooting chlorine demand spikes during seasonal algal blooms or biofilm detachment events

FAQ

What sample conditioning is required prior to HR-400 installation?
A representative, pressure-regulated side-stream (typically 0.5–2.0 L/min) with particulate filtration ≤5 µm and optional dechlorination bypass for zero-check validation is recommended. No chemical reagents or carrier gases are needed.
Can the HR-400 measure combined chlorine (chloramines)?
Yes—when operated in total chlorine mode using DPD-based reagentless oxidation (via optional built-in iodide catalyst layer), it differentiates free vs. total chlorine by sequential electrochemical reduction steps.
How often does the sensor require recalibration?
Under stable operating conditions, field calibration is typically performed every 7–14 days using NIST-traceable chlorine standard solutions; sensor replacement interval is 12–18 months depending on oxidant exposure history.
Is the HR-400 compatible with existing SCADA infrastructure?
Yes—native Modbus RTU support enables direct integration with Allen-Bradley, Siemens S7, and Schneider EcoStruxure platforms without protocol gateways.
Does HORIBA provide validation documentation for IQ/OQ protocols?
Yes—Factory Acceptance Test (FAT) reports, sensor certificate of conformance, and electronic calibration records are supplied with each unit; site-specific OQ templates are available upon request.