YEX-S1PRO-CL Online Residual Chlorine Sensor | YexSensor

YEX-S1PRO-CL Online Residual Chlorine Sensor: Stable Online Residual Chlorine Monitoring for Industrial Water Quality Projects

YEX-S1PRO-CL Online Residual Chlorine Sensor Product Introduction

YexSensor YEX-S1PRO-CL belongs to the YexSensor S1 PRO stainless-steel sensor series. It is designed for continuous residual chlorine monitoring in natural water, industrial water, laboratory water, municipal wastewater and automated water quality systems. The sensor outputs hypochlorous acid, residual chlorine, pH and temperature for easier process evaluation and remote data acquisition.

The product uses constant-voltage method with pH and temperature compensation, 316L stainless steel + ABS housing and NPT 3/4 thread installation. It supports RS-485 Modbus communication, with optional 4-20mA output available according to project integration requirements.

For residual chlorine applications, the most important engineering concerns are stable readings, clear parameter interpretation and low-maintenance integration. YEX-S1PRO-CL addresses these needs by combining constant-voltage method with pH and temperature compensation, Residual chlorine: +/-5% of reading; pH +/-0.1; temperature +/-0.1 C accuracy performance, 10 s response behavior and RS-485 Modbus communication in one compact probe.

S1 PRO Series Positioning and Engineering Advantages

The S1 PRO series is positioned as the upgraded high-accuracy stainless-steel sensor line. Compared with standard plastic-housing sensor configurations, this series highlights higher measurement accuracy, 316L stainless steel structure, IP68 protection, automatic temperature compensation, digital Modbus integration and optional analog output. It is suitable for system integrators who need stable field deployment, compact wiring and precise parameter reading.

The sensor is suitable for projects where hypochlorous acid, residual chlorine, pH and temperature must be sent continuously to a PLC, RTU, data logger or cloud gateway. Digital Modbus data reduces signal attenuation over distance, while optional 4-20mA output keeps the product compatible with older analog control panels. This dual integration path helps engineering teams standardize cabinet wiring without sacrificing site flexibility.

Core Technical Highlights

• 316L stainless steel + ABS housing: The robust housing supports demanding field installation while keeping the probe compact for tanks, pipes and immersion points.

• High-accuracy temperature channel: Temperature accuracy reaches +/-0.1 C, supporting reliable compensation and more stable residual chlorine data.

• RS-485 / 4-20mA output options: Standard RS-485 Modbus output supports PLC, RTU, data logger and IoT gateway integration, while optional 4-20mA can be selected for analog systems.

• Outputs: Outputs hypochlorous acid, residual chlorine, pH and temperature for disinfection control.

• Automatic: Automatic pH and temperature compensation improves chlorine measurement reliability.

Wide Application Scenarios and System Integration Solutions

YEX-S1PRO-CL Online Residual Chlorine Sensor can be integrated into PLC, SCADA, RTU and water quality IoT systems. The product is suitable for repeated online measurement points where offline sampling is slow, data continuity is weak, or on-site wiring space is limited.

1. Drinking Water Disinfection
   Used for continuous online residual chlorine monitoring; it supports stable disinfection or water safety control with continuous online data.

2. Swimming Pool Control
   Used for continuous online residual chlorine monitoring; it supports stable disinfection or water safety control with continuous online data.

3. Industrial Circulating Water
   Used for continuous online residual chlorine monitoring; it supports process control, alarm logic and compliance-oriented trend records.

4. Municipal Water Supply Monitoring
   Used for continuous online residual chlorine monitoring; it provides continuous online data for system control, alarms and historical trend analysis.

For engineering contractors, this means the same product can be used across new monitoring stations, retrofit control panels and OEM water quality cabinets. The digital output simplifies data mapping, while the stainless-steel construction helps improve long-term reliability in outdoor and industrial environments.

Engineering Selection, Interference and Project Acceptance

Measurement Meaning and Selection Boundary

Residual chlorine, free chlorine, total chlorine and hypochlorous acid are not interchangeable terms. Confirm the required analytical definition and reference method before setting acceptance limits. Provide disinfectant type, residual range, pH range, temperature, pressure, sample flow and whether the control target is free residual chlorine or another chlorine definition.

Installation Risk and Data Quality

Rapid pH change, low sample flow, membrane or electrode fouling, oxidants other than chlorine and long periods without water contact can affect stability. Use a representative flow cell or well-mixed point and compare with the project reference method.

System Integration and Alarm Design

Map the primary measurement, temperature and communication status as separate engineering tags. Configure process high/low alarms independently from communication-loss, out-of-range and rate-of-change alarms. Filtering should be limited to what the process response permits so a real step change is not hidden.

Commissioning and Acceptance

Record the sensor model, range, unit, output option, device address, baud rate and reference method. Compare simultaneous online and reference results at representative conditions, then function-test alarms, historical trends and any control interlock from probe to HMI. Acceptance should cover the complete measurement loop rather than only the local probe value.

YEX-S1PRO-CL Online Residual Chlorine Sensor Technical Performance Specifications

Installation Guidance and Electrical Connection Instructions

Installation Position Recommendations

The sensor can be installed by immersion, or mounted in a pipe or tank through the NPT 3/4 thread. For electrochemical and optical sensors, avoid upside-down or horizontal installation when the application requires a stable liquid contact surface. Keep the measuring area fully immersed and avoid strong bubbles or sediment impact where possible.

Electrical Wiring

Connection reference: 1-red power positive, 2-black power negative, 3-green 485B, 4-yellow 485A, 5-optional 4-20mA output. Wire colors may vary by batch, so the connector mark or pin number should be used as the final reference.

Maintenance, Care and Calibration Guide

At least one third of the sensor should be inserted into the measured liquid so the measuring end is fully covered. Keep wiring terminals, measuring surface and aviation connector clean. Clean the measuring surface with a soft brush and avoid scratching optical windows, electrodes or membranes.

The sensor is calibrated before delivery. Calibration is not recommended unless necessary. If long-term use causes data drift, perform zero or slope calibration according to the communication protocol and site standard solution.

Frequently Asked Questions

Q1: What does YEX-S1PRO-CL measure, and what decision can the data support?

A1: YEX-S1PRO-CL uses electrochemical residual-chlorine measurement with pH and temperature compensation for continuous residual chlorine sensor monitoring. It is intended to support drinking-water disinfection, secondary water supply, swimming pools and industrial disinfection loops. Define whether the signal will be used for display, alarm, process comparison, automatic control or compliance screening, because each purpose requires different limits and verification.

Q2: What measurement limitation should engineers understand before specifying this sensor?

A2: Residual chlorine, free chlorine, total chlorine and hypochlorous acid are not interchangeable terms. Confirm the required analytical definition and reference method before setting acceptance limits.

Q3: What information is required to select the correct range and configuration?

A3: Provide disinfectant type, residual range, pH range, temperature, pressure, sample flow and whether the control target is free residual chlorine or another chlorine definition.

Q4: Which site conditions can interfere with the reading?

A4: Rapid pH change, low sample flow, membrane or electrode fouling, oxidants other than chlorine and long periods without water contact can affect stability. Use a representative flow cell or well-mixed point and compare with the project reference method.

Q5: Where should the sensor be installed?

A5: Choose a continuously wetted and representative point after adequate mixing. Avoid dead zones, direct chemical-injection impact, sediment accumulation and locations where bubbles collect. Keep the sensing area fully immersed and follow the NPT 3/4 mounting and orientation requirements in the supplied manual.

Q6: How should RS-485 Modbus be commissioned with a PLC or SCADA system?

A6: Verify 12-24 VDC power, A/B polarity, device address, baud rate, register order, engineering unit and decimal scaling. Create a separate communication-status alarm so a frozen or missing value is not interpreted as normal water quality. Acceptance should compare the probe display, PLC register and HMI value across the complete loop.

Q7: When should optional 4-20mA be selected?

A7: Choose RS-485 Modbus when digital values, multiple channels, diagnostics or multidrop networking are required. Choose the optional 4-20mA configuration for an existing analog-only controller or a conventional point-to-point loop. The output options are selected according to the order; confirm the mapped parameter and full-scale value before production.

Q8: What maintenance and verification routine is recommended?

A8: Inspect the sensing surface, cable, seals and connector; remove deposits using the method stated in the manual and avoid scratching optical windows, membranes or electrodes. Compare the stabilized online result with the agreed site reference after commissioning, process changes or cleaning. Recalibrate only after installation, reference-method and fouling effects have been excluded.

Quality Assurance and After-sales Service

YexSensor is committed to providing an excellent product experience.

Strict quality inspection: Each product goes through a standardized inspection process and 72-hour aging test to help ensure a defect rate below 2%.

One-year warranty: A one-year after-sales warranty is provided from the date of sale, excluding man-made damage or improper use.

Cable configuration: A 5-meter four-core shielded cable is the standard cable configuration.