Yexsensor YEX-CL-406-A Online Residual Chlorine Sensor: High-precision Constant Voltage Monitoring Terminal

In water treatment processes, real-time monitoring of residual chlorine content is the key link to ensure disinfection effect and prevent secondary pollution. Yexsensor's YEX-CL-406-A online residual chlorine sensor, based on the **Constant Voltage** measurement principle, overcomes the limitations of traditional membrane electrodes such as slow response, easy clogging, and frequent replacement of membranes and electrolytes. It provides system integrators and water engineering companies with a highly reliable, low-maintenance digital monitoring solution.

The sensor integrates temperature compensation, signal transmission and digital communication functions, and can be directly connected to PLC, DCS or various IoT monitoring terminals to achieve continuous and accurate sensing of hypochlorous acid (HClO) concentration in aqueous solutions.

Core Technical Advantages: Constant Voltage Method Measurement Principle

YEX-CL-406-A adopts the constant voltage method. Its core structure consists of two platinum electrodes (gold electrode) and one reference electrode. By maintaining a constant polarization potential between the measuring electrode and the reference electrode, hypochlorous acid molecules in water undergo electrochemical reduction reaction on the surface of the measuring electrode.

Membrane-free Design: No need to replace permeable membrane or replenish electrolyte, significantly reducing consumable costs and on-site maintenance frequency.

Fast Response: Compared with membrane sensors, the constant voltage method can more quickly sense subtle fluctuations in chlorine concentration in water quality.

Anti-interference Ability: Built-in precision filtering circuit can effectively suppress the interference of on-site electromagnetic environment on weak current signals.

YEX-CL-406-A Online Residual Chlorine Sensor Technical Performance Indicators and Engineering Specifications

As an industrial-grade water quality instrument, Yexsensor fully considers measurement accuracy and environmental tolerance in its design.

1. Core Technical Parameters Table

2. Hardware and Installation Specifications

YEX-CL-406-A Online Residual Chlorine Sensor Engineering Installation and Electrical Integration Specification

1. Dynamic Flow-through Installation
   The measurement accuracy of the residual chlorine sensor has a certain dependence on flow rate. YEX-CL-406-A must be used with the supporting flow cell.

Flow Rate Control: It is recommended to keep the flow rate stable at 30-60 L/h. Too low flow rate will lead to insufficient reactant supply and low measured value; too large flow rate fluctuation will cause numerical drift.

Position Selection: The sensor should be tightly installed in the flow cell, and the measuring end should be close to the water inlet area to avoid facing the water outlet or generating dead air bubbles.

2. Electrical Connection Definition
   Five-core twisted shielded cable is used to ensure anti-interference ability of digital communication:

• Red (VCC): Power positive pole (12～24V DC)

• Black (GND): Ground wire / power negative pole

• Blue (485A): RS-485 signal A

• Green (485B): RS-485 signal B

• Yellow (I-Out): 4-20 mA analog output (if not selected, please keep floating and isolated)

YEX-CL-406-A Online Residual Chlorine Sensor Typical Application Scenarios

• Waterworks and Secondary Water Supply: Monitor residual chlorine content in factory water and pipe network terminals to ensure that the residual disinfection amount meets national drinking water hygiene standards.

• Swimming Pool Water Quality Control: Real-time feedback of residual chlorine data to dosing pumps to achieve precise dosing of disinfectants and avoid discomfort caused by excessive chlorine.

• Industrial Circulating Cooling Water: Monitor residual chlorine in cooling tower operation to effectively control biological slime and algae growth.

• Food and Beverage Production: Compliance monitoring of canning production lines and food processing water.

• Sewage Treatment Plant Monitoring: Monitor residual chlorine level after tail water disinfection to prevent excessive chlorine from being discharged into natural water bodies.

Maintenance and Calibration Logic

1. Electrode Activation
   New electrodes or electrodes stored dry for a long time must be statically activated in tap water for 24 hours before use. Electrodes that have not been fully activated may show significantly low values or slow response.

2. Calibration Specification
   Zero point calibration: Use chlorine-free water (such as water filtered by activated carbon or high-purity distilled water) and execute after the value is stable.
   Slope calibration: It is recommended to perform under flowing conditions. Use the supporting flow cell to pass in a standard solution of known concentration, or take real-time operating water samples and measure with DPD colorimetric method (national standard method) for manual slope correction.

Frequently Asked Questions (FAQ)

Q1: Why does YEX-CL-406-A not need to replace electrolyte and membrane?

A1: Because it adopts the constant voltage electrochemical principle, the metal electrode directly contacts the water sample to be measured and reacts, without involving membrane permeation process, so there is no problem of electrolyte depletion or membrane pollution and clogging.

Q2: Will changes in pH value in water affect residual chlorine measurement?

A2: Yes. The form of residual chlorine (HClO and ClO⁻) is greatly affected by pH. The sensor is designed to work in the pH range of 4～9. If the application environment has drastic pH fluctuations, it is recommended to integrate a pH sensor in the system for algorithm compensation or maintain stable water quality pH.

Q3: Why is the value measured by the sensor lower than the value of DPD manual test?

A3: First confirm whether the sensor has been fully activated (24 hours); secondly check whether the flow rate of the flow cell is stable at 30-60 L/h; finally check whether the electrode surface is blocked by oil or air bubbles.

Q4: Can this sensor be used to detect chlorine dioxide or ozone?

A4: The constant voltage principle has certain spectral selectivity, but different strong oxidants will respond at specific potentials. If precise measurement of chlorine dioxide is required, please contact Yexsensor technical department to obtain a model calibrated for specific media.

Q5: How to clean the platinum electrode surface if it is dirty?

A5: You can wipe with a soft cloth and tap water. For stubborn dirt, you can quickly rinse with very dilute hydrochloric acid solution and immediately rinse with plenty of clean water. It is strictly prohibited to scrape the electrode surface with hard objects.

Q6: Does it support long-distance signal transmission?

A6: Yes. Through RS-485 Modbus RTU protocol, the signal transmission distance can reach more than 1000 meters, effectively avoiding attenuation and fluctuation of analog signals during long-distance transmission.

Q7: Does ambient temperature affect sensor life?

A7: The sensor is designed for operating environment of 5～50°C. It is strictly prohibited to place the sensor in a freezing environment, otherwise it may cause internal structure damage.

Q8: Why does the output value show 0, but there is obvious chlorine smell in the water?

A8: Please check whether the wiring is loose and whether the power supply voltage is within 12～24V. If the circuit is normal, please reactivate and check whether the measurement potential is set correctly.

Summary

Yexsensor YEX-CL-406-A online residual chlorine sensor, with its excellent constant voltage technology, not only meets the high-precision requirements of water quality monitoring, but also greatly reduces the total cost of ownership (TCO) of system operation through membrane-free and low-consumption design. For system integrators who pursue high equipment stability and simple maintenance, this probe is the core sensing cornerstone of online water quality monitoring systems.