Nexisense ZW-RCl101 Residual Chlorine Detection Module: Industrial-Grade Low-Power Residual Chlorine Online Monitoring Integrated Solution

In engineering projects such as municipal water supply network endpoint residual chlorine decay monitoring, medical wastewater disinfection tail water compliant discharge, swimming pool circulating water disinfectant dosing closed-loop, secondary water supply pumping station water quality assurance, industrial park medical/pharmaceutical wastewater total outlet online assessment, residual chlorine serves as the core indicator of residual oxidant in drinking water/medical wastewater disinfection. Its continuous, reliable, low-power online measurement has become a rigid requirement for water plant finished water quality acceptance, network endpoint safety assurance, disinfectant optimization in disinfection processes, direct data transmission to regulatory platforms, and project completion acceptance. Traditional DPD colorimetric methods or intermittent analyzers can no longer meet 24/7 unattended, high-reliability, fast-response, low-power edge integration, and real-time closed-loop requirements with PLC/SCADA.

Nexisense ZW-RCl101 residual chlorine detection module adopts mature electrochemical principle + sophisticated circuit design. Residual chlorine molecules pass through a selective membrane and are reduced at the cathode to produce a current signal linearly proportional to concentration, range 0～20 mg/L, t63≤90 s, resolution 0.01 mg/L, RS485 digital output, module power consumption<60 mW, suitable for tap water plants, medical wastewater, swimming pools and other scenarios. The product supports Modbus RTU protocol, industrial-grade protection design, operating temperature 10～40℃, meeting engineering-level requirements such as explosion-proof in municipal/medical hazardous scenarios and EMC Level IV. It has passed third-party metrological type approval and EMC testing.

Typical Industrial Project-Level Application Scenarios

1. Tap Water Plant Finished Water and Network Endpoint Residual Chlorine Decay Monitoring
   ZW-RCl101 module is deployed at clear water tank outlet, booster pumping stations and network endpoints, combined with pH, turbidity, flow meters to form multi-parameter monitoring station. RS485 signal connects to water plant SCADA or network GIS platform, achieving automatic alarm when residual chlorine<0.3 mg/L, residual chlorine decay trend analysis, and network endpoint safety assurance, meeting the online monitoring requirements of Drinking Water Sanitation Standard (GB 5749-2022).

2. Medical Wastewater Disinfection Tail Water Residual Chlorine Compliant Discharge Control
   After sodium hypochlorite/chlorine dioxide disinfection in hospitals/disease control centers, tail water residual chlorine needs to be controlled at 0.5～2 mg/L. ZW-RCl101 module is installed at contact tank outlet or total outlet, combined with ORP/pH sensors to form nodes, RS485 output connects to PLC to achieve automatic dosing of reducing agent (sodium bisulfite) when residual chlorine exceeds high limit, ensuring compliant tail water residual chlorine discharge.

3. Swimming Pool Circulating Water Disinfectant Dosing Closed-Loop Regulation
   Residual chlorine in swimming pool circulating water directly determines disinfection effectiveness and swimmer comfort. ZW-RCl101 module is installed at circulating pump backend or return line, output connects to PLC, achieving automatic increase of sodium hypochlorite dosing pump frequency when residual chlorine

   <0.5 l="" and="" decrease="" when="">1.5 mg/L, maintaining residual chlorine stable at 0.5～1.0 mg/L, reducing irritating odor and skin discomfort risks.

4. Secondary Water Supply Pumping Station Water Quality Assurance and Endpoint Residual Chlorine Monitoring
   High-rise buildings/community secondary water supply systems are prone to residual chlorine decay. ZW-RCl101 module is deployed at pump house outlet and endpoint sampling points, supporting linkage with turbidity and pH. When residual chlorine<0.3 mg/L, it triggers chlorine dosing pump or alarm, combined with network GIS to achieve full-network residual chlorine distribution visualization and anomaly localization.

5. Industrial Park Medical/Pharmaceutical Wastewater Total Outlet Online Assessment
   Park medical wastewater total outlets require real-time residual chlorine residual monitoring. ZW-RCl101 module is integrated into multi-parameter online analyzers, networked with COD, ammonia nitrogen, pH, supporting NB-IoT/4G direct transmission to environmental platforms, achieving automatic tracing of residual chlorine anomalies and exceedance warnings.

ZW-RCl101 Residual Chlorine Module Selection and Engineering Integration Guide

Key Selection Parameters (For Engineering Procurement)

System Integration and On-Site Deployment Considerations

• Pre-treatment: Residual chlorine is susceptible to bubbles, oil, suspended solids interference. Recommended to configure automatic deaerator + pre-filter unit (pore size 10～50 μm), or bypass filtration circulation.

• Installation Method: Flow-through cell type (recommended DN50～DN80 pipeline bypass), immersion type (with protective cage), lance type (portable inspection). Flow-through cell requires flow velocity 0.1～0.3 m/s to avoid dead zones.

• Electrical & Communication: RS485 bus uses shielded twisted pair + terminating resistor (120Ω), each segment ≤1200 m; power supply recommended independent 12V DC industrial power + lightning protection module.

• Host System Docking: RS485 Modbus RTU polling cycle recommended 1～5 s, supports direct communication with Siemens S7/TIA Portal, Schneider EcoStruxure, Honeywell Experion, KingView/Kunlun Tongtai, etc.; for cloud platforms, add Modbus to MQTT/OPC UA gateway.

• Redundancy & Reliability: Critical monitoring points recommend 1+1 redundant modules + dual-channel acquisition, automatic module failure switchover with maintenance alarm.

• On-Site Calibration: Factory provides ISO 17025 traceable calibration certificate, on-site recommended two-point calibration using 0 mg/L (sodium thiosulfate solution) and saturated residual chlorine water.

• EMC & Lightning Protection: Product passed IEC 61000-6-2/4 industrial-grade EMC test, recommended to install power surge protector and signal surge protector on site.

Nexisense OEM/Customization and Bulk Supply Advantages

• Module Structure Customization: Supports special sizes, smaller package, extended leads, array multi-point layout, special range (0～5 mg/L high-precision drinking water version).

• Communication & Edge Processing Customization: In addition to standard RS485 Modbus RTU, supports OPC UA Server, MQTT TLS, LoRa private protocol, NB-IoT/4G transparent transmission, customizable firmware (local residual chlorine trend judgment, over-limit linkage chlorine dosing logic, breakpoint resume).

• Bulk Delivery Capability: Monthly capacity over 150,000 units, core electrochemical components and circuit boards produced in-house, standard lead time 4～6 weeks, urgent orders compressible to 3 weeks.

• Quality & Certification: Full process ISO 9001 + ISO 14001 management, products passed CE, RoHS, third-party EMC, explosion-proof (some models Ex ia), metrological type approval certificate.

• Engineering Implementation Support: Provides SDK, Modbus register mapping table, CAD installation drawings, EMC/lightning protection design guidance, on-site joint commissioning, engineer training, and long-term spare parts inventory commitment.

Real Project Application Cases

1. East China Large Municipal Water Plant Network Endpoint Residual Chlorine Decay Monitoring Project
   Deployed 150 sets of ZW-RCl101 modules at finished water, booster stations and endpoint sampling points, RS485 output connected to water plant SCADA system, achieving automatic alarm when residual chlorine<0.3 mg/L and trend analysis. After commissioning, network endpoint residual chlorine compliance rate increased to 98.7%, secondary pollution incidents decreased by about 65%.

2. South China Tertiary Hospital Medical Wastewater Disinfection Tail Water Residual Chlorine Compliance Project
   Deployed 30 sets of ZW-RCl101 at contact tank outlet and total outlet, combined with ORP/pH to form nodes, data connected to Siemens S7-1500 PLC, achieving automatic sodium bisulfite dosing when residual chlorine >2 mg/L. After operation, tail water residual chlorine exceedance rate dropped to 0, annual disinfectant consumption reduced by about 28%.

3. Yangtze River Delta Large Swimming Pool Circulating Water Disinfectant Dosing Closed-Loop Project
   Deployed 20 sets of ZW-RCl101 at circulating pump backend, RS485 output connected to PLC, achieving automatic increase of sodium hypochlorite dosing frequency when residual chlorine<0.5 mg/L. After system commissioning, swimming pool water irritating odor complaints decreased by 90%, disinfectant usage optimized by about 22%.

Frequently Asked Questions (FAQ)

1. What are the main differences between ZW-RCl101 residual chlorine module and traditional DPD colorimetric method in engineering applications?
   Electrochemical module enables continuous, unattended measurement, response time ≤90 s, no chemical reagent consumption or waste liquid treatment; DPD colorimetric is intermittent, suitable for laboratory, cannot meet automatic station direct transmission and disinfection process interlocking requirements.

2. How to ensure long-term stability of the module in high turbidity medical wastewater scenarios?
   Recommended to configure front automatic deaerator + filter unit (pore size 10～50 μm), daily automatic high-pressure backflush 1～2 times, module regular zero-point verification, typical maintenance cycle 6～12 months, drift controlled within ±5%.

3. How to prevent common signal issues in long-distance transmission with RS485 Modbus RTU bus?
   Recommended to use shielded twisted pair + terminating resistor (120Ω), each segment ≤1200 m; avoid parallel routing with strong power cables, add signal isolator and lightning protection module to ensure stable communication.

4. How does the residual chlorine module meet high precision requirements of<0.3 mg/L in municipal water supply network endpoint monitoring?
   Select high-stability electrochemical assembly, cooperate with daily 0/saturated residual chlorine two-point calibration, use module with metrological type approval to ensure indication error <±0.05 mg/L, meeting GB 5749-2022 online monitoring requirements.

5. How to achieve closed-loop control of residual chlorine concentration with PLC chlorine dosing pump?
   Module RS485 output connects to PLC or edge gateway, PLC uses built-in PID algorithm or threshold logic, increasing chlorine dosing pump frequency/opening when residual chlorine < set value, supports remote modification of set values and PID parameters.

6. How to extend module life in high salinity swimming pool circulating water?
   Select high salinity corrosion resistant membrane material, cooperate with automatic freshwater flushing program (daily or weekly timed), typical life extended from 2 years to more than 3 years.

7. How to ensure consistency between batches and long-term spare parts supply for bulk purchases?
   Provide batch consistency statement, core electrochemical component batch number traceability, 3～5 year spare parts inventory commitment, EOL advance notice 12 months prior with replacement solutions.

8. What core qualifications and test reports need to be submitted for residual chlorine online monitoring system project acceptance?
   Metrological type approval certificate (CPA), CMA/CMA qualification report, ISO 9001 quality system certificate, module protection test report, EMC test report, power lightning protection test report, third-party comparison test report.

9. How to achieve automated precise regulation through residual chlorine and ORP data in medical wastewater disinfection projects?
   Set residual chlorine >2 mg/L to trigger reducing agent dosing, ORP <+600 mV to trigger additional disinfectant; Nexisense edge gateway supports local simple logic control, reducing cloud dependency and network latency risks.

10. How does the residual chlorine module meet data direct transmission and anomaly tracing requirements in tap water plant projects?
    Supports NB-IoT/4G transparent transmission to regulatory platform, built-in data cache + breakpoint resume function; residual chlorine anomaly can link pH, turbidity, flow and other multi-factor data to generate tracing curves, facilitating water quality anomaly tracing and emergency response.

Conclusion

The core value of industrial water quality monitoring lies in providing credible, continuous, low-power residual chlorine and other key parameter data support, helping system integrators and EPC contractors achieve disinfection process closed-loop control, compliant discharge supervision, and risk early warning. Nexisense ZW-RCl101 residual chlorine detection module, with electrochemical high stability, ultra-low power consumption, RS485 digital output, and modular integration capabilities as core, provides stable and reliable edge perception solutions for high-requirement projects such as municipal water supply, medical wastewater, swimming pool circulating water.

In the context of drinking water safety, standardized medical wastewater discharge, and accelerated implementation of smart water affairs, selecting a module and edge computing partner with long-term supply assurance, fast customization response, and on-site implementation experience will directly determine project delivery quality, operation and maintenance costs, and long-term value.

System integrators, EPC contractors, and project technical leaders who need residual chlorine module selection, communication scheme design, prototype verification, bulk quotation, or joint bidding support for specific working conditions are welcome to contact the Nexisense technical team at any time. We will provide targeted solution recommendations and on-site support to jointly promote the high-quality development of municipal water supply safety, medical wastewater compliance, and smart water affairs.