Online Water COD and Turbidity Sensor

I. Working Principle

The sensor measures with two light paths: one for COD and one for turbidity. Dissolved organic matter in water absorbs ultraviolet light, so the COD value can be derived from the transmittance of the light source. The second light path measures turbidity and compensates for it automatically, while temperature is acquired at the same time for temperature compensation.

II. Key Features

1. UV254 absorption method with dual light sources - COD and turbidity measured in one sensor.

2. COD range 0–1000 mg/L (default) and turbidity range 0–400 NTU (default).

3. Automatic turbidity compensation and automatic temperature compensation.

4. Built-in automatic cleaner prevents biological attachment and optical window fouling; cleaning time and cycle count are configurable (0.7 W).

5. RS485 (Modbus/RTU) output.

6. ABS and 316L stainless steel housing with IP68 protection.

7. Two-point calibration.

III. Technical Parameters

IV. Installation and Wiring

Do not install the sensor upside down; install it at an angle of at least 15° to the horizontal.

The cable is a 5-core shielded cable: red - power supply, black - ground, green - RS485-A, white - RS485-B.

V. Maintenance and Care

If the sensor needs cleaning, use warm water with an appropriate amount of detergent.

Avoid strong vibration, which may damage the front optical glass, and never scrape it with hard objects.

VI. Calibration

The sensor is closely calibrated at the factory and normally requires no user calibration. If user calibration has been performed, the factory settings can be restored with the appropriate command.

Zero-point calibration: immerse the sensor in a container of distilled or purified water; after 30 seconds, when the value is stable, perform turbidity zero-point calibration and COD zero-point calibration according to the communication instructions.

Slope calibration: immerse the sensor in a solution of known turbidity; after 30 seconds, when the value is stable, perform turbidity slope calibration. Repeat with a solution of known COD value for COD slope calibration.