Chlorine is the world’s most widely used drinking water disinfectant. It’s effective, affordable, and leaves residual chlorine to protect water as it travels through pipes. But too little fails to kill pathogens; too much creates bad taste, corrosion, and harmful byproducts. Accurate, continuous residual chlorine monitoring is not optional—it’s a public health necessity.
This guide covers why residual chlorine matters, global standards, monitoring technologies, and a field‑ready solution: the ERUN-K6I Online Residual Chlorine Sensor (Flow-through Type).
Why Residual Chlorine Monitoring Matters
Residual chlorine is your “insurance policy” against microbial regrowth in pipelines.
Scenario | Consequence |
Too low | Bacterial regrowth; risk of E. coli, Legionella, etc. |
Too high | Bad taste/odor; pipe corrosion; carcinogenic byproducts (THMs) |
Global Standards You Must Know
Standard | Authority | Free Residual Chlorine Range |
WHO Drinking Water Guidelines | WHO | 0.2–5.0 mg/L |
U.S. EPA (MRDL) | EPA | Max 4.0 mg/L |
GB 5749-2022 (China) | China | ≥0.3 mg/L (outlet); ≥0.05 mg/L (tap) |
Swimming Pools | Industry | 1–3 mg/L |
During cholera outbreaks, WHO recommends 0.2–2.0 mg/L depending on application.
Traditional vs. Modern Monitoring
Method | Best For | Limitation |
DPD Colorimetric | Field/lab, rapid | Reagents, not continuous |
Test Strips | Quick screening | Semi‑quantitative |
Online Amperometric Sensors | 24/7 real‑time monitoring | Higher initial cost |
Introducing the ERUN-K6I Online Residual Chlorine Sensor (Flow‑through Type)
The ERUN-K6I is a next‑generation online sensor developed by ERUN Group. It features high stability and high precision, measuring residual chlorine and temperature in solution.
Click image for details
Parameter | Specification |
Principle | Constant Voltage (Amperometric) |
Range | 0.00–20.00 mg/L |
Accuracy | ±2% FS |
Temp. Range | 0.0–60.0℃ |
Pressure Range | 0–1 bar |
Temp. Compensation | Automatic / Manual |
Flow Rate | 15–30 L/h |
pH Range | 5–9 |
Housing Material | ABS |
Cable Length | 5 m (standard) |
Connection | M39×1.5 |
Output | 4‑20 mA (Load <500Ω) |
Communication | RS485 (Modbus) |
Power | DC 9–30 V |
IP Rating | IP68 |
Installation | Flow‑through type |
Key Features & Benefits
High precision & stability – ±2% FS, constant voltage method trusted worldwide.
Wide range (0–20 mg/L) – One sensor for drinking water, pools, and industry.
Automatic temperature compensation – Accurate readings from 0–60℃.
Dual output – 4‑20 mA analog + RS485 digital (Modbus) for PLC/SCADA/IoT.
IP68 waterproof – Fully submersible, suitable for harsh environments.
Flow‑through design – M39×1.5 connection ensures stable flow (15–30 L/h), minimizing air bubbles.
Wide power compatibility – DC 9‑30 V works with battery or industrial supplies.
Applications Across Industries
Drinking water treatment plants – Optimize chlorine dosage, avoid byproducts.
Municipal tap water networks – Maintain residuals to prevent regrowth.
Wastewater effluent – Comply with discharge permits.
Swimming pools & recreational water – Automate 1–3 mg/L free chlorine monitoring.
Industrial cooling water – Prevent biofouling in towers and heat exchangers.
Boiler feed water – Avoid excess chlorine that accelerates corrosion.
Aquaculture – Ensure dechlorinated water to protect fish.
Food & beverage – Monitor rinse water for sanitation without affecting taste.
Why Choose ERUN-K6I?
Feature | Benefit |
Constant voltage method | Industry‑standard, reliable |
0–20 mg/L range | Covers all applications |
±2% FS accuracy | Regulatory compliance |
Automatic temp. compensation | Stable readings |
4‑20 mA + RS485 | Easy integration with existing systems |
IP68 | Works outdoors, wet areas |
Flow‑through design | Consistent flow, fewer errors |
DC 9‑30 V | Flexible power options |
Conclusion
Residual chlorine monitoring is a cornerstone of water safety, regulatory compliance, and equipment protection. With markets growing and standards tightening, you need a reliable, accurate, continuous monitoring solution.
The ERUN-K6I Online Residual Chlorine Sensor (Flow‑through Type) delivers lab‑grade accuracy in a rugged, industrial package. Whether you manage a water treatment plant, cooling system, or swimming pool, this sensor provides real‑time, trustworthy data.
Learn more & request a quote for ERUN-K6I
Contact ERUN Environmental Technology Group
• Email: nawei@xayingrun.com
• Website: https://www.erunwas.com
ERUN – Your Trusted Partner in Water Quality Monitoring Solutions
