NBL-WQ-DO Online Fluorescence Dissolved Oxygen Sensor

The NBL-WQ-DO online fluorescence dissolved oxygen integrated sensor is designed and manufactured based on the physical principle of fluorescence quenching excited by specific substances. When excitation light is directed at the fluorescent material on the surface of the fluorescent film head, the fluorescent material is excited and emits fluorescence. The fluorescence quenching time is affected by the concentration of oxygen molecules on the surface of the fluorescent film head. 

By detecting the phase difference between the fluorescence and the excitation light and comparing it with the internal calibration curve, the concentration of oxygen molecules can be calculated, and the final value can be output after temperature and salinity compensation. It requires no electrolyte and will not be polarized. It does not consume oxygen and is not affected by flow rate. Built-in temperature sensor, automatic temperature compensation. Free from interference by chemicals such as sulfides. Low drift, fast response, more accurate measurement. Long service life, lower operating cost. Simple replacement of the fluorescent cap. RS-485 interface, Modbus/RTU protocol. Low power consumption, anti-interference.

Technical Specifications of NBL-WQ-DO Online Fluorescence Dissolved Oxygen Sensor

1. Operating Principle

The NBL-WQ-DO online fluorescence dissolved oxygen integrated sensor is designed and manufactured based on the physical principle of fluorescence quenching excited by specific substances. When excitation light is directed at the fluorescent material on the surface of the fluorescent film head, the fluorescent material is excited and emits fluorescence. The fluorescence quenching time is affected by the concentration of oxygen molecules on the surface of the fluorescent film head. By detecting the phase difference between the fluorescence and the excitation light and comparing it with the internal calibration curve, the concentration of oxygen molecules can be calculated, and the final value can be output after temperature and salinity compensation.

No electrolyte required, no polarization.

No oxygen consumption, not affected by flow rate.

Built-in temperature sensor, automatic temperature compensation.

Built-in salinity compensation, flexible parameter configuration.

Free from interference by chemicals such as sulfides.

Low drift, fast response, more accurate measurement.

Long service life, lower operating cost.

Simple replacement of the fluorescent cap.

RS-485 interface, Modbus/RTU protocol.

Low power consumption, anti-interference.

2. Installation and Electrical Connection

2.1. Installation

The sensor must be fixedly installed below the liquid level. Avoid collision or scratching against the surface of the fluorescent film head during installation and use. The fluorescent film head part must be protected from adhesion of bottom sediments. Remove the rubber cover before use.

2.2. Electrical Connection

Red wire - Power wire (12～24 V)

Black wire - Ground wire (GND)

Blue wire - 485A

White wire - 485B

Carefully check the wiring sequence before powering on to avoid unnecessary losses caused by wiring errors.

Cable Specification: Since the cable is submerged in water (including seawater) for a long time or exposed to air, all wiring points must be treated for waterproofing, and the user's cable must have certain corrosion resistance.

3. Maintenance

3.1. Maintenance Schedule and Methodology

3.1.1 Maintenance Schedule

Different from the electrochemical principle dissolved oxygen sensor technology, the fluorescence dissolved oxygen sensor does not consume oxygen and does not require frequent cleaning (except when used in viscous liquids).

Note: The maintenance frequency in the above table is only recommended, and maintenance personnel should clean the sensor according to the actual usage of the sensor; however, the replacement frequency of the fluorescent cap is recommended once a year.

3.1.2 Maintenance Method

a) External surface of the sensor: Wipe the external surface of the sensor with tap water. If debris remains, clean it with a soft damp cloth. For persistent dirt, you can add household detergent to the tap water for cleaning.

b) Surface of the fluorescent film head: If there is dirt on the surface of the sensor's fluorescent film head, rinse it with clean water or gently wipe it with a soft cloth. Pay attention to the cleaning intensity to avoid scratching the measuring area and affecting the measurement accuracy.

c) Inside the fluorescent film head: Generally no cleaning required. If water vapor or dust enters the fluorescent film head, the cleaning steps are as follows:

Unscrew the fluorescent film head;

Rinse the inner surface of the fluorescent film head and the optical window of the sensor.

For oily dirt, you can use household cleaning solution;

Gently dry the water with a clean lint-free cloth and let it air dry;

4. Reinstall the fluorescent film head.

d) Check the sensor cables: There should be no damage to the cable sheath and cable roots; the terminals must not be submerged in water; when the sensor is installed normally, the cable must not be under tension, otherwise the internal cable wires will easily break and the sensor will not work normally.

e) Check if the sensor housing is damaged by corrosion or other causes.

f) Daily storage of the fluorescent film head: When not in use, cover with a protective rubber cap with a damp sponge to keep the surface of the sensor's fluorescent film head measuring area moist. If the measuring area surface of the sensor's fluorescent film head is chronically dry, measurement errors or unstable data will occur, and it must be soaked in water for 48 hours before use.

NBL-WQ-DO Online Fluorescence Dissolved Oxygen Sensor Data Sheet

NBL-WQ-DO Online Fluorescence Dissolved Oxygen Sensor.pdf