YEX-RDO-406 Online Fluorescence Dissolved Oxygen Sensor

The YEX-RDO-406 online fluorescence dissolved oxygen sensor launched by Yexsensor is a high-performance integrated dissolved oxygen monitoring device designed based on the physical fluorescence quenching principle. This sensor completely abandons the many limitations of traditional electrochemical dissolved oxygen probes. It requires no electrolyte, consumes no oxygen, is unaffected by water flow velocity, and is not interfered with by common chemical substances such as sulfides, providing long-term stable and accurate dissolved oxygen data in complex water environments.

Dissolved oxygen (DO) is a core indicator for evaluating water self-purification capacity, aquatic organism living environment, and wastewater treatment process efficiency. The YEX-RDO-406 is available in standard type (YEX-RDO-406-A) and high-range type (YEX-RDO-406-S), meeting different monitoring needs from drinking water sources to high-concentration aeration tanks. The sensor adopts IP68 waterproof design, supports submersible installation, has fast response (T90＜30s), low drift, and low operating cost. It is an ideal online dissolved oxygen solution for municipal sewage, industrial wastewater, aquaculture, river and lake ecological monitoring, and other fields.

YEX-RDO-406 Online Fluorescence Dissolved Oxygen Sensor Core Advantages

The YEX-RDO-406 online fluorescence dissolved oxygen sensor has multiple leading advantages that significantly improve user experience and monitoring reliability:

• Fluorescence quenching principle: No oxygen consumption, unaffected by water flow velocity, and measurement is not interfered with by chemical substances such as sulfides and chlorides.

• Maintenance-free characteristics: No need to add electrolyte, no electrode polarization, longer service life, and lower operating costs.

• Intelligent compensation function: Built-in Pt1000 temperature sensor and salinity compensation parameter settings, which can automatically perform precise compensation according to actual water body conditions.

• Fast response and high stability: Response time <30s, low drift, maintaining excellent accuracy even during long-term continuous operation.

• Convenient maintenance design: Fluorescent membrane cap replacement is simple, daily cleaning is easy, and no complex tools are required.

• Flexible output methods: Standard RS-485 Modbus/RTU protocol, supporting seamless integration with various automation systems. Optional 4-20mA current output is available.

• Rugged and durable: Multiple housing material options including POM/ABS/PC alloy, TC4 titanium alloy, or 316L stainless steel, adapting to different corrosive environments.

• Low power consumption design: Only 0.2W@12V, suitable for long-term deployment in solar-powered or remote monitoring stations.

These advantages make the YEX-RDO-406 the preferred product for users seeking “stable, accurate, and low-maintenance” dissolved oxygen monitoring.

YEX-RDO-406 Online Fluorescence Dissolved Oxygen Sensor Working Principle

The YEX-RDO-406 online fluorescence dissolved oxygen sensor works based on the fluorescence quenching principle.

When excitation light of a specific wavelength irradiates the fluorescent material on the surface of the fluorescent membrane cap, the fluorescent material is excited and emits fluorescence. In the presence of oxygen molecules, oxygen molecules collide with the excited fluorescent material, resulting in shortened fluorescence lifetime (i.e., fluorescence quenching). The sensor detects the phase difference between the fluorescence signal and the excitation light through a precision optical system and compares it with the internal calibration curve to accurately calculate the concentration of oxygen molecules in the water body.

The final measured value is processed by the built-in temperature sensor (Pt1000) and salinity compensation algorithm before output, ensuring reliable dissolved oxygen concentration (mg/L) or saturation (%) data under different temperature and salinity conditions.

Compared with traditional electrochemical methods, this principle has significant advantages such as no oxygen consumption, no flow rate limitation, strong resistance to chemical interference, and low drift. It is particularly suitable for applications requiring long-term online continuous monitoring.

YEX-RDO-406 Online Fluorescence Dissolved Oxygen Sensor Technical Specifications

YEX-RDO-406 Online Fluorescence Dissolved Oxygen Sensor Typical Application Scenarios

The YEX-RDO-406 online fluorescence dissolved oxygen sensor is widely used in the following fields:

1. Wastewater Treatment Plant Process Control
          Real-time monitoring of dissolved oxygen concentration in aeration tanks, aerobic tanks, anaerobic tanks, etc., to precisely control aeration volume, achieve energy saving and consumption reduction, while ensuring biochemical treatment efficiency and effluent compliance.

2. Aquaculture and Aquatic Industry
          In fish, shrimp, and crab breeding ponds, aeration systems, and aquatic seedling farms, dissolved oxygen is a key parameter affecting biological survival and growth. The sensor helps farmers monitor water dissolved oxygen status in real time, promptly activate aeration equipment, and reduce breeding risks.

3. Drinking Water Sources and Surface Water Monitoring
          Installed at water intakes of reservoirs, rivers, and lakes to monitor dissolved oxygen levels in natural water bodies, assess aquatic ecological health, and provide data support for water source protection and drinking water plant process adjustments.

4. Industrial Wastewater Treatment
          In wastewater treatment systems of chemical, pharmaceutical, food processing and other industries, monitoring dissolved oxygen helps optimize biological treatment processes and prevent low treatment efficiency or secondary pollution caused by hypoxia or over-aeration.

5. River and Lake Ecological Environment and Smart Water Management
          Environmental monitoring departments can build water quality monitoring networks to track long-term dissolved oxygen change trends, evaluate water eutrophication and self-purification capacity in combination with other parameters, and provide scientific basis for ecological restoration decisions.

The sensor supports remote data transmission and can seamlessly integrate with SCADA, PLC, or IoT platforms to achieve unmanned intelligent monitoring.

Installation and Electrical Connection

Installation Requirements:

The YEX-RDO-406 adopts submersible installation. Please note the following during installation:

• Immerse the sensor below the liquid surface and fix it securely to avoid collision or scratching of the fluorescent membrane cap;

• The fluorescent membrane cap part should avoid long-term attachment by bottom sediment;

• Remove the rubber protective cap before use;

• Install at a moderate flow rate and representative location.

Electrical Connection:

The sensor is equipped with a 5-core twisted shielded cable, with clear wire sequence definition:

• Red wire — Power positive pole (12～24V DC)

• Black wire — Ground (GND)

• Blue wire — 485A

• White wire — 485B

• Yellow wire — Current output (optional, can be left floating if not used)

Before powering on, carefully check the wiring sequence. It is recommended to perform strict waterproof treatment on all wiring points, especially when used in seawater or corrosive environments. The cable should have good corrosion resistance.

Maintenance and Care Guide

The maintenance requirements of the YEX-RDO-406 fluorescence dissolved oxygen sensor are much lower than traditional electrochemical probes, but standardized maintenance can further extend service life.

Maintenance Schedule Recommendations:

• Clean the sensor outer surface and fluorescent membrane cap once every 30 days;

• Check the sensor and fluorescent membrane cap for damage every 30 days;

• Replace the fluorescent membrane cap once a year;

• Perform two-point calibration regularly according to regulatory requirements.

Daily Maintenance Methods:

• Rinse the sensor outer surface with clean water; for stubborn dirt, wipe with a soft cloth and a small amount of household detergent;

• Gently wipe dirt on the fluorescent membrane cap surface with clean water or a soft cloth to avoid scratches;

• If water or dust enters inside the membrane cap, unscrew the cap for internal cleaning, dry thoroughly, and reinstall;

• Check the cable for damage or tension;

• When not in use, cover the fluorescent membrane cap with a rubber protective cap containing a wet sponge to keep the measurement area moist.

Calibration Method:

Two-point calibration is used:

1. Zero point calibration: Use 5% anhydrous sodium sulfite solution and calibrate after the value stabilizes.

2. Slope calibration: Perform in air-saturated water (recommended) or water-saturated air and calibrate after stabilization.

Precautions:

• Avoid direct sunlight exposure on the inner surface of the fluorescent membrane cap;

• It is strictly prohibited to touch the fluorescent membrane directly with hands;

• Avoid air bubbles attaching to the membrane surface during measurement and calibration;

• Avoid applying any mechanical stress or scratches to the fluorescent membrane.

FAQ

Q1. What are the advantages of YEX-RDO-406 compared to traditional electrochemical dissolved oxygen sensors?

The fluorescence method requires no electrolyte, consumes no oxygen, is unaffected by flow rate and sulfide interference, has lower maintenance, longer service life, and more stable measurement. It is the preferred solution for modern online monitoring.

Q2. How often does the fluorescent membrane cap need to be replaced?

It is recommended to replace it once a year under normal use conditions. The actual replacement frequency can be adjusted appropriately according to water quality pollution level and usage environment.

Q3. Does the sensor support salinity compensation?

Yes. It has built-in salinity compensation function. Users can set parameters according to the actual water salinity to ensure measurement accuracy in seawater, brackish water, or high-salinity wastewater environments.

Q4. How to determine if the fluorescent membrane cap needs replacement?

When the measurement value continues to be unstable, drift is large after calibration, or the membrane cap surface is obviously damaged, it is recommended to replace the membrane cap in time.

Q5. What key points should be noted during installation?

Ensure the fluorescent membrane cap is fully submerged, avoid collision or scratching of the membrane cap, remove the protective cap, and fix the sensor at a representative water flow position.

Q6. How does the sensor integrate with existing control systems?

The standard RS-485 Modbus/RTU protocol is compatible with the vast majority of PLC, DCS, and IoT platforms. Optional 4-20mA output is available, making integration very convenient.

Q7. What could cause abnormal fluctuations in measurement values?

Common causes include the fluorescent membrane cap not being tightened, dirt attached to the outer surface, membrane cap damage, or exceeding service life. It is recommended to first clean the membrane cap, check installation, and recalibrate.

Q8. What about product warranty and after-sales service?

Yexsensor provides a one-year warranty from the date of sale (excluding improper use). If technical problems occur, our technical support team will provide quick response, including remote guidance, spare parts supply, or factory repair.

Why Choose Yexsensor?

Yexsensor focuses on the research and manufacturing of online water quality monitoring sensors, always adhering to the product philosophy of “professional, reliable, and solution-oriented”. The YEX-RDO-406 has undergone strict 72-hour aging tests, stability tests, and environmental simulation tests to ensure that every sensor meets high-quality standards before leaving the factory.

We not only provide high-performance hardware but also are committed to providing customers with complete technical support from selection, installation to later maintenance, helping users build efficient and stable water quality dissolved oxygen monitoring systems.

Take action now:
       If you are looking for an online fluorescence dissolved oxygen sensor that requires no frequent maintenance, accurate measurement, and long-term stability, the YEX-RDO-406 will be your ideal choice. Welcome to contact the Yexsensor sales or technical team to obtain detailed quotations, customized solutions, or on-site demonstrations. We look forward to working with you to jointly protect water body health and water environment safety!