Fluorescence Based Dissolved Oxygen Sensor HM-S8

Working principle

The fluorescence based dissolved oxygen sensor is designed based on the quenching principle of excitation fluorescence by specific substances in physics. When the excitation light is irradiated onto the fluorescent substance on the surface of the fluorescent film head, the fluorescent substance is excited and emits fluorescence. The extinguishing time of the fluorescence is affected by the concentration of oxygen molecules on the surface of the fluorescent film head. The concentration of oxygen molecules can be calculated by detecting the luminescence lifetime of fluorescence, and the final value can be output after temperature, pressure, and salinity compensation.

Technical Specifications

Measurement principle: Fluorescence lifetime method

Range: 0-20mg/L

Resolution: 0.01mg/L

Accuracy: ± 2%, ± 0.3 ℃

Temperature compensation: automatic temperature compensation

Output mode: RS-485 (Modbus/RTU), 4-20mA

Storage temperature: -5~+65 ℃

Working environment: 0-50 ℃,<0.3MPa

Installation method: Immersion installation, 3/4NPT installation thread

Cable length: 5m

Power consumption: 0.2W, 12V power supply

Power supply DC: 12V-24V

Protection level: IP68

Calibration method: two-point calibration

Size/Installation

1. Dimensional drawing

2. Wiring diagram

The cable is a 4-core shielded wire:

Red line - power cord

Blue wire - Ground wire (GND) Green wire -485B

Yellow line -485A

The cable color may vary slightly depending on the production batch, please refer to the cable silk screen printing for details.

3. Installation

Before powering on, carefully check the wiring sequence to avoid unnecessary losses caused by wiring errors, and waterproof treatment should be carried out at the wiring points.

Maintenance and upkeep

1) Outer surface of sensor: Rinse the outer surface of the sensor with clean water. If there is still dirt residue, wipe it with a damp soft cloth. For stubborn dirt, add some household detergent to the water to clean it.

2) Fluorescent film head surface: If there is dirt on the surface of the fluorescent film head, please rinse with water or gently wipe with a soft cloth. When cleaning, pay attention to the force to avoid scratching the measurement area and affecting the measurement accuracy.

3) If the measurement value is too high or too low, the fluorescent film head should be cleaned and stirred during measurement to prevent the surface of the film head from being attached by foreign objects.

Sensor calibration

5.1 Zero point calibration

Add 95mL of water to 5g of sodium sulfite and stir evenly. Place the sensor into the solution and wait for 3 minutes for the value to stabilize. Then, perform zero point calibration according to the communication instructions.

5.2 Slope calibration

Place the sensor in air saturated water and wait for about 3 minutes for the values to stabilize before performing slope calibration. Follow the communication instructions to perform zero calibration.

5.3 Precautions

Avoid exposing the inner surface of the fluorescent film to sunlight or strong light. Do not touch the fluorescent film with your hands or sharp objects

Avoid attaching bubbles to the surface of the fluorescent film during use

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