1. Product Overview
1.1 What Is a COD Sensor?
A Chemical Oxygen Demand (COD) sensor is a device used to measure the amount of oxygen required to oxidize organic and inorganic substances in water. It is essential for water quality monitoring because it provides a direct indication of the pollution level of a water body. The KWS series COD sensors, based on advanced technologies, deliver efficient and accurate water quality monitoring solutions, making COD measurement more convenient and more reliable.
COD sensors can quickly reflect the degree of organic pollution in water—the higher the COD value, the greater the concentration of organic pollutants. Elevated COD levels may lead to water eutrophication, adversely affect the survival of aquatic organisms, and even pose risks to human health through drinking water sources. Therefore, selecting a high-quality COD sensor is critical for effective water quality management across various industries. Whether in industrial wastewater treatment, municipal sewage monitoring, or surface water environmental management, COD sensors provide core data support for water quality assessment, helping professionals promptly understand and control water pollution conditions.
1.2 COD Sensors vs. Traditional Monitoring Methods
Traditional water quality monitoring typically relies on manual sampling and laboratory analysis, which is time-consuming, labor-intensive, and incapable of providing real-time data. As a result, sudden water quality changes may go undetected, increasing environmental risks and potential economic losses.
The KWS series COD sensors address these limitations through continuous online monitoring. In addition to COD, they can simultaneously measure BOD, TOC, TSS, turbidity, and temperature, delivering real-time data feedback. This enables rapid response to water quality changes, effective pollution control, reduced manual sampling workload, and significantly improved monitoring efficiency.
2. KWS Series COD Sensor Specifications Comparison
| Model | KWS-100 | KWS-110 | KWS-150 | KWS-190 |
| COD Range & Accuracy | 0–500 mg/L ±5% 0–1500 mg/L ±5% | 0–500mg/L ±5% 0–1500mg/L ±5% | 0–200 mg/L ±5% 0–500 mg/L ±5% 0–1500 mg/L ±5~10% | 0–500mg/L ±5% 0–1500mg/L ±10% |
| TOC Range & Accuracy | 0–180 mg/L 0–600 mg/L | / | 0–120 mg/L 0–300 mg/L 0–900 mg/L | 0–200 mg/L 0–600 mg/L |
| BOD Range & Accuracy | / | 0–400mg/L 0–1200mg/L | / | 0–300 mg/L 0–900 mg/L |
| TSS Range & Accuracy | / | 0–3000mg/L ±5% 0–5000mg/L ±5% | / | / |
| Turbidity Range & Accuracy | 0–500 NTU ±5% | / | 0–200 NTU 0–400 NTU 0–1000 NTU | 0–1000 NTU |
| Material | 316L Stainless Steel | 316L | 316L | 316L |
| Operating Temp. & Pressure | 0–50 °C, 3 bar | 0–50 °C, 3 bar | 0–45 °C, 0.2 MPa | 0–60 °C, 0.1 MPa |
| Protection Rating | IP68 | IP68 | IP68 | IP68 |
| Output | RS485 Modbus | RS485 Modbus | RS485 Modbus Optional 4–20 mA | RS485 Modbus |
| Power Supply | 12–24 VDC | 12–24 VDC | 12-24 VDC | 12–24 VDC |
| Cable Length | 10 m | 10 m | 5 m | 5 m |
| Calibration Method | Single-point Two-point | Single-point Two-point | Single-point | Multi-point |
3. Key Parameter Interpretation
| Parameter | Description | Application Guidance |
| COD Range & Accuracy | Range: COD concentration range the sensor can accurately measure. Accuracy: Deviation between measured and actual values. | Surface water & drinking water: 0–200 mg/L, 0–500 mg/L Domestic & general industrial wastewater: up to 0–1500mg/L |
| TOC | Total carbon content of organic pollutants in water. | Key indicator for evaluating overall organic pollution levels. |
| BOD | Amount of dissolved oxygen consumed by microorganisms decomposing organic matter. | Used to assess water self-purification capacity and biodegradability of wastewater. |
| TSS | Actual mass of suspended particles in water. | Helps evaluate physical pollution and predict fouling risks in equipment such as RO membranes. |
| Turbidity | Degree of light scattering caused by suspended particles. | Rapid indicator of visual water quality, commonly used for drinking water and RO pretreatment monitoring. |
| Calibration Method | Supported calibration types (single-point, two-point, multi-point). Calibration aligns sensor readings with certified reference standards. | Sensor performance may drift over time due to temperature, usage frequency, and component aging. Regular calibration ensures accuracy and extends sensor lifespan. |
4. Step-by-Step Selection Guide
Step 1: Determine the Measurement Range
● First, determine the COD concentration range of the liquid to be measured. If no historical data is available, a portable COD analyzer can be used for preliminary testing to identify the typical range and maximum COD value.
● It is recommended to select a COD sensor with a measurement range slightly higher than the actual monitoring range (typically 1.2–1.5 times the expected maximum value) to avoid inaccurate readings caused by sudden increases in COD levels.
Step 2: Determine the Required Measurement Accuracy
● Define the required COD measurement accuracy based on the monitoring purpose.
● High-precision monitoring scenarios (such as discharge compliance monitoring and drinking water source monitoring): models with ±5% accuracy are recommended.
● Other monitoring scenarios (such as on-site rapid screening and preliminary pollution assessment): models with ±10% accuracy are sufficient.
Step 3: Consider Additional Functions
● COD sensors are usually capable of measuring not only COD, but also other water quality parameters such as TOC, BOD, TSS, and turbidity. Sensors with additional functions can be selected according to specific requirements.
Step 4: Consider Installation and Communication Requirements
● COD sensors require immersion installation and therefore need to be fixed underwater. (Standard accessories usually include clamps; mounting brackets or protective housings should be prepared separately.)
● For long-distance data transmission and multi-sensor networking: choose RS485 output (Modbus protocol), which is supported by all models.
● If the existing system uses analog instruments (requiring a 4–20 mA signal): select the KWS-150 model, which supports optional 4–20 mA output and can be directly integrated into existing systems.
Step 5: Consult Professionals
● If you are still unsure about the selection, you can consult the professional technical team at KACISE. They will provide more targeted recommendations based on your specific requirements and on-site conditions.
5. Typical Application Scenarios
| Application | Recommended Model | Reason |
| Drinking Water Monitoring | KWS-150 | Wide range options; 0–200 mg/L range with ±5% accuracy meets drinking water monitoring requirements. |
| Surface Water Monitoring | KWS-100 / KWS-110 | Suitable range options; 0–500 mg/L versions align well with surface water COD levels. |
| Industrial Water & Wastewater | KWS-100 / KWS-110 KWS-150 / KWS-190 | 0–1500mg/L range covers most industrial applications; multi-parameter monitoring enables comprehensive water quality evaluation. |
6. Summary
To help you quickly select the right KWS series COD sensor, the key points are summarized below:
By comparing KWS series specifications, users can initially screen models based on measurement range, accuracy, operating temperature, and pressure requirements. Understanding the meaning of core parameters ensures optimal matching with real-world applications. Finally, following the five-step selection process—range determination, accuracy selection, additional functions, installation and communication, and professional consultation—helps avoid selection errors.
The typical application table provides direct references for common use cases, allowing fast and confident model selection.
If you still have questions or require a customized COD monitoring solution, feel free to contact us. Our professional team will provide one-on-one guidance to help you choose the most cost-effective COD sensor for your application.
If you are unsure which model to choose, feel free to contact us with your application details for technical support.
