YEX-RDO-406-S Online Fluorescence Dissolved Oxygen Sensor

The YEX-RDO-406-S Online Fluorescence Dissolved Oxygen Sensor is a highly reliable integrated online dissolved oxygen monitoring device launched by the Yexsensor brand. It adopts the fluorescence quenching principle design, enabling real-time dissolved oxygen detection with no consumption, high precision, and no frequent maintenance.

The sensor range covers 0～20.00 mg/L (0～200% saturation, 25℃), with a resolution of 0.01 mg/L. It is particularly suitable for water treatment scenarios that require long-term stable operation. Through RS-485 Modbus/RTU protocol and optional 4-20mA current output, it can be easily integrated into PLC, SCADA, DCS or IoT water quality monitoring systems, helping users achieve precise dissolved oxygen control, energy optimization and process intelligent management, ensuring water quality compliance and significantly reducing operation and maintenance costs.

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

Yexsensor YEX-RDO-406-S takes fluorescence optical technology as the core, completely overturning the limitations of traditional electrochemical dissolved oxygen sensors, and providing users with a low-maintenance, high-stability, and high cost-performance solution. Compared with polarographic or galvanic electrodes, this sensor requires no electrolyte, no polarization, no oxygen consumption, and is not affected by water flow velocity, fundamentally solving the problems of easy electrode aging, large drift, and frequent maintenance.

The main highlights of the product are as follows:

• Fluorescence quenching measurement principle: No oxygen consumption, fast response, not limited by flow rate, suitable for static or flowing water bodies.

• No electrolyte or polarization required: Eliminates the common problems of electrolyte replacement and signal attenuation in traditional electrodes.

• Built-in temperature and salinity compensation: Pt1000 automatic temperature compensation + flexible salinity parameter setting, adapting to freshwater, seawater and different temperature environments.

• Strong anti-interference ability: Not affected by chemical substances such as sulfide and H₂S, especially suitable for complex sewage or industrial wastewater.

• Small drift and fast response: Accurate and stable measurement, fluorescent membrane head life is about 1 year, easy to replace.

• High protection and durable design: IP68 protection level, full 316L stainless steel shell, corrosion-resistant and high-pressure resistant, can be used for long-term submersion.

• Low power consumption and anti-interference: 0.2W@12V, supports standard 5-meter cable and can be customized, suitable for remote or distributed monitoring.

• Easy maintenance features: Fluorescent membrane head replacement is simple, daily cleaning frequency is low, and overall usage cost is significantly reduced.

These advantages make the YEX-RDO-406-S the preferred device for wastewater treatment aeration energy saving, aquaculture precise oxygenation, environmental water monitoring, and industrial process control, helping users achieve smarter and more economical dissolved oxygen management.

Detailed Working Principle of YEX-RDO-406-S Online Fluorescence Dissolved Oxygen Sensor

The YEX-RDO-406-S Online Fluorescence Dissolved Oxygen Sensor works based on the physical fluorescence quenching principle. When excitation light of a specific wavelength illuminates the fluorescent material on the surface of the fluorescent membrane head, the material is excited and emits fluorescence. Oxygen molecules collide with the excited fluorescent molecules, causing the fluorescence lifetime (quenching time or phase difference) to shorten. The sensor accurately detects the phase difference between the fluorescence and the excitation light, compares it with the internal calibration curve, thereby calculating the oxygen molecule concentration. Finally, after temperature and salinity compensation, it outputs a stable and accurate dissolved oxygen value (mg/L or % saturation).

The core technical advantages of this principle include:

• Zero oxygen consumption: No oxygen diffusion process is required, the measurement is not affected by water stirring or flow rate, and is suitable for low-flow or still water environments.

• High selectivity and stability: The fluorescent dye is highly sensitive to oxygen molecules and is not affected by most common chemical interferents.

• Multi-parameter automatic compensation: Built-in temperature sensor realizes Pt1000 automatic compensation, users can flexibly set salinity parameters, ensuring accuracy within ±2%F.S. in a wide temperature and salinity range.

• Optical non-consumptive design: Compared with electrochemical methods, it has smaller drift, faster response and longer life.

The fluorescent membrane head adopts high-durability optical materials, combined with 316L stainless steel shell and IP68 sealing structure, enabling the sensor to operate reliably for a long time under harsh water quality conditions, widely meeting the needs of online continuous monitoring.

Technical Parameters and Specifications of YEX-RDO-406-S Online Fluorescence Dissolved Oxygen Sensor

Application Scenarios of YEX-RDO-406-S Online Fluorescence Dissolved Oxygen Sensor

The YEX-RDO-406-S Online Fluorescence Dissolved Oxygen Sensor is widely used in multiple key fields that require precise and real-time dissolved oxygen control, providing users with data-driven process optimization and risk early warning solutions.

• Wastewater Treatment Plant Aeration System Control: Real-time monitoring of dissolved oxygen concentration in activated sludge aeration tanks, linked with blowers and frequency converters to achieve precise aeration adjustment. It can maintain optimal microbial activity while significantly reducing energy consumption (aeration energy consumption usually accounts for more than 50% of the total energy consumption of wastewater treatment plants), helping enterprises achieve energy saving and carbon reduction goals.

• Intelligent Management of Aquaculture: In high-density fish, shrimp and crab farming ponds or recirculating aquaculture systems, dissolved oxygen is a key parameter affecting survival rate and growth speed. The sensor can be linked with oxygenation equipment or alarm systems to prevent hypoxia-induced fish death while avoiding energy waste and water disturbance caused by excessive oxygenation.

• Drinking Water Treatment and Industrial Process Water Monitoring: In tap water plants, boiler feed water, industrial cooling circulating water, food and beverage production water and other fields, monitoring dissolved oxygen can promptly detect oxidation corrosion risks or process abnormalities, ensuring equipment life and product water quality compliance.

• Environmental Water Monitoring and River and Lake Management: In natural water bodies, landscape water bodies, and black and odorous water body remediation projects, it is used to evaluate water self-purification capacity, eutrophication status and remediation effects, supporting data collection and scientific decision-making by environmental protection regulatory departments.

• Other Extended Applications: Laboratory water quality analysis platforms, marine environmental monitoring, bioreactor control and other scenarios.

During installation, it is recommended to submerge the sensor below the liquid surface, avoid the fluorescent membrane head contacting bottom sediment, and maintain moderate water flow to obtain more representative measurement values.

Installation and Electrical Connection Guide

Installation Requirements:

• Use submersible fixed installation to ensure the sensor probe is completely below the liquid surface.

• The installation position should avoid the fluorescent membrane head from being attached by sediment, mechanical collision or scratching.

• Before use, the protective rubber cap must be removed, and the membrane head surface should be kept moist during operation.

• When installing the cable, keep it naturally slack to avoid internal wire breakage caused by tension.

Electrical Connection:

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

• Red wire: Power positive pole (12～24VDC)

• Black wire: Ground (GND)

• Blue wire: 485A

• Green wire: 485B

• Yellow wire: Current output (can be left floating if not used)

Before powering on, please carefully check the wiring sequence to avoid equipment damage caused by incorrect wiring. All wiring points must be properly waterproofed and sealed, and the cable should have certain anti-corrosion capability. After powering on, verify normal communication through Modbus protocol or current output, and then it can be officially put into online monitoring use.

Yexsensor provides professional installation guidance and technical support to help users quickly complete on-site deployment and achieve stable and reliable operation.

Maintenance and Care Solutions

The fluorescence method design of YEX-RDO-406-S significantly reduces the maintenance burden. Users can maintain the sensor's long-term high-precision performance through simple and standardized operations.

Recommended Maintenance Schedule:

• Clean the sensor outer surface and fluorescent membrane head every 30 days (except in viscous liquid environments).

• Check the sensor and fluorescent membrane head for damage every 30 days.

• Replace the fluorescent membrane head once a year (under normal use conditions).

• Perform two-point calibration according to the requirements of the competent department or actual measurement drift.

Specific Maintenance Methods:

• Outer surface cleaning: Rinse with clean water. If there is residual dirt, wipe with a damp soft cloth. Stubborn dirt can be treated with a small amount of household detergent.

• Fluorescent membrane head surface: Rinse with clean water or wipe gently with a soft cloth. Avoid scratching the measurement area during cleaning.

• Internal cleaning of fluorescent membrane head (when water or dust enters): Unscrew the membrane head, rinse the inner surface and sensor optical window with clean water. Oil stains can be treated with detergent, wipe dry and reinstall.

• Cable and shell inspection: Ensure the cable is not damaged, the connection is not immersed in water, and the shell has no corrosion damage.

• Storage when not in use: Cover with the protective rubber cap with a moist sponge inside to keep the fluorescent membrane head moist. If the membrane head is dry for a long time, it needs to be soaked in water for 48 hours before use to restore performance.

Calibration Operation Guide:

• Zero point calibration: Weigh 5g sodium sulfite, prepare 5% sodium sulfite solution, immerse the sensor, and perform zero point calibration after the value stabilizes for 3 minutes.

• Slope calibration: Place the sensor in air-saturated water (or water-saturated air), and perform slope calibration after stabilizing for 3 minutes.

• Air-saturated water preparation method: Add 2/3 volume of fresh distilled water to a constant temperature water bath, float a porous plastic sheet on it, continuously aerate with an air pump for more than 1 hour, stop aeration and let it stand for about 20 minutes before use.

Precautions:

• Avoid air bubbles attaching to the fluorescent membrane head surface, hand contact contamination or mechanical stress (squeezing, scratching).

• Do not expose the inner surface of the fluorescent membrane head to sunlight for a long time.

• If foreign matter adheres to the temperature measurement area (stainless steel shell), gently remove it with a soft brush.

• Keep the membrane head surface moist during measurement and calibration.

Standardized maintenance can control sensor drift at an extremely low level, extend the overall service life and reduce long-term operating costs of enterprises.

FAQ

Q1. What are the significant advantages of fluorescence dissolved oxygen sensors compared to traditional electrochemical sensors?

Fluorescence method requires no electrolyte, no oxygen consumption, is not affected by flow rate, has low maintenance frequency, strong anti-interference ability, and longer life. It is the preferred solution for long-term online monitoring.

Q2. How long is the service life of the fluorescent membrane head? Does it need frequent replacement?

Under normal use conditions, it is recommended to replace it once a year. The actual frequency can be appropriately adjusted according to the degree of water pollution. The replacement operation is simple and convenient.

Q3. Is this sensor suitable for complex water quality environments such as wastewater treatment plants?

Very suitable. The fluorescence method is not affected by interferences such as sulfides. The IP68 protection and 316L stainless steel shell can withstand long-term submersion in harsh conditions such as sewage and seawater.

Q4. What work is required for daily maintenance?

Clean the sensor and membrane head surface with clean water every 30 days. Avoid scratching the membrane head and regularly check whether the membrane head is damaged.

Q5. What should be done if the measurement value deviates or is unstable?

Common causes include dirt on the membrane head surface, membrane head damage or exceeding service life. It is recommended to clean the membrane head first and stir the water body. If the problem persists, replace the membrane head.

Q6. What output methods are supported? How to integrate with existing systems?

It supports RS-485 Modbus/RTU protocol and optional 4-20mA current output, which can be directly connected to PLC, SCADA or water quality cloud platforms. Yexsensor provides detailed protocol documents and integration technical guidance.

Q7. What are the key precautions during installation?

Ensure the sensor is completely submerged, avoid the membrane head contacting bottom sediment or being collided. After removing the protective cap, keep the membrane head moist, waterproof the cable and avoid tension.

Q8. How is the product warranty period and after-sales service guaranteed?

Yexsensor provides one-year warranty service from the date of sale (excluding improper use). The product comes standard with the sensor host, instruction manual and certificate of conformity. If you encounter any technical problems, you can contact us at any time for calibration guidance, membrane head replacement and professional after-sales support.

Quality Assurance and After-sales Service

Yexsensor has a standardized quality inspection process and is equipped with advanced testing equipment. Each YEX-RDO-406-S sensor undergoes 72-hour aging experiments and stability tests to ensure 100% qualified delivery. If the product batch failure rate reaches 2%, it will be directly returned and replaced, and the supplier will bear all related costs.

Standard Accessories:

• 1 × YEX-RDO-406-S sensor host

• 1 × Instruction manual

• 1 × Certificate of conformity

• Standard 5-meter 5-core shielded cable

We are committed to providing full-process professional after-sales service, including technical consultation, on-site installation guidance, regular calibration support, and rapid supply of spare parts such as fluorescent membrane heads. Choosing Yexsensor YEX-RDO-406-S means choosing a stable, reliable, and cost-controllable dissolved oxygen monitoring solution.