YEX-DDM-406 Industrial Online Salinity Sensor Product Introduction

In fields such as marine engineering, special aquaculture, and high-salt wastewater treatment, small changes in salinity often determine ecological balance and production efficiency. Yexsensor's YEX-DDM-406 online salinity sensor is a professional-grade water quality monitoring terminal that integrates corrosion resistance, digital intelligence, and high stability.

This sensor not only breaks through the limitations of traditional contact electrodes that are prone to polarization and scaling in extreme high-salt environments, but also provides a maintenance-free and long-life online salinity monitoring solution for global system integrators through the combination of TC4 titanium alloy material and digital inductive measurement technology.

Core Technical Advantages: Why Choose YEX-DDM-406?

1. Top Material: TC4 Titanium Alloy and ABS Composite Shell
In high-salinity environments (such as seawater or industrial brine), ordinary metals and low-end plastics are prone to electrochemical corrosion or stress cracking. The key contact parts of YEX-DDM-406 use TC4 titanium alloy, which is known for its extremely high strength and excellent resistance to chloride ion corrosion. Combined with a tough ABS body, it ensures long-term operation of the equipment in harsh fluids without damage.

2. Leading Principle: Digital Inductive Electrode Method
Unlike traditional metal sheet contact measurement, YEX-DDM-406 adopts an inductive principle. Its advantage is that the measuring end establishes a current loop through electromagnetic induction. The electrode is not directly exposed to the measured medium, completely eliminating polarization effects and greatly reducing the impact of oil, dirt, and biological attachment in water on measurement accuracy.

3. Dual Signal Compatibility: RS485 and 4-20mA
To adapt to different industrial site requirements, this device provides powerful communication compatibility:
       • RS485 (Modbus RTU): Digital output with strong anti-interference ability, supporting long-distance multi-node networking, and directly docking with PLC or cloud platforms.
       • 4-20mA (optional): Standard analog signal output, compatible with traditional industrial controllers and recorders.

4. Ultimate Protection and Automatic Compensation
       • IP68 Protection: Strict encapsulation process, supporting deep-water immersion installation.
       • Pt1000 Compensation: Built-in high-sensitivity platinum resistance, real-time monitoring of water temperature and automatic temperature compensation to ensure constant and reliable readings in the 0～50℃ range.

Comprehensive Application Scenarios

Marine Environmental Monitoring and Scientific Research
In coastal monitoring stations, marine ranches, and scientific research buoy systems, YEX-DDM-406 can be fixed underwater for a long time to record salinity fluctuations in real time. Its high resolution of 0.1 PSU can accurately capture the impact of ocean current changes and freshwater injection on local sea areas.

Smart Aquaculture (Factory Farming)
For aquaculture species such as sea cucumbers, abalones, and groupers that are extremely sensitive to salinity, salinity fluctuations directly affect survival rates. By connecting YEX-DDM-406 to an automation control system, automatic water replenishment or automatic salt addition can be realized to create a constant growth environment.

Industrial Wastewater Treatment and High-Salt Wastewater Reduction
In electroplating, papermaking, and chemical industries, the treatment of high-salt wastewater is a challenge. The sensor can monitor the operating efficiency of desalination processes (such as reverse osmosis RO and electrodialysis EDR) online, monitor the salinity of concentrated liquid in real time, and help achieve zero liquid discharge (ZLD) goals.

Brackish Water Desalination and Boiler Feed Water
In desalination projects, salinity is a core indicator for measuring the quality of finished water. The response time (T90) of YEX-DDM-406 is less than 30 seconds, enabling rapid early warning of sudden water quality changes and protecting expensive downstream pumps, valves, and process equipment.

Technical Performance and Specifications

Installation Guidance and Electrical Connection Specifications

Installation Method Description

1. Immersion Installation: The sensor is connected to an extension rod through the 3/4 NPT thread at the rear and vertically immersed in the pool or channel.

2. Pipeline Installation: Use a T-type tee and corresponding adapters to embed the sensor into the industrial flow pipeline. Pay attention to the fluid flow direction toward the front end of the sensor.

3. Key Distance: To avoid electromagnetic interference and wall effects, the sensor should be ≥5 cm from the bottom of the container and ≥2 cm from the side wall during installation.

Electrical Connection (5-core Shielded Wire Definition)

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

• Black wire: Power negative pole (GND)

• Blue wire: 485A (communication)

• Green wire: 485B (communication)

• Yellow wire: 4-20mA current output (if not used, please leave it floating, do not short circuit)

Special Note: The cable joints must be waterproofed. Due to the strong electrolytic nature of salt water, any water seepage may cause capillary phenomenon in the cable, thereby corroding the internal circuit of the sensor.

Maintenance and Professional Calibration Solutions

Although YEX-DDM-406 adopts an anti-pollution design, regular cleaning is still the key to ensuring long-term accuracy.

1. Cleaning Method: Use a soft brush to remove attachments (such as seaweed and shellfish) on the shell and sensing area. It is strictly forbidden to use metal sharp tools to scrape the titanium alloy surface. Rinse with distilled water after cleaning.

2. Zero Point Calibration: Place the sensor in the air and let it stand still. After the temperature is balanced and the surface is dry, perform air zero point calibration through RS485 commands.

3. Slope Calibration: Prepare a salinity standard solution above 10% of the full scale. Completely immerse the sensor in the calibration solution, ensure no air bubbles are attached to the sensing hole, and send the calibration command after the reading is stable.

Frequently Asked Questions

Q1: What does the “PSU” unit of the YEX-DDM-406 sensor mean?

A1: PSU refers to “Practical Salinity Unit”, which is the most commonly used salinity expression in marine science today. It is numerically very close to per mille (‰) or g/L and can accurately reflect the total amount of dissolved salts in water.

Q2: Does the sensor support use in high-temperature acid-base environments?

A2: The operating temperature range of this product is 0～50℃. TC4 titanium alloy has excellent corrosion resistance, but if it involves strong oxidizing acids (such as fuming nitric acid) or extreme environments exceeding 60℃, please consult the Yexsensor technical team for evaluation.

Q3: Why are inductive sensors more durable than traditional metal electrodes?

A3: Traditional electrodes rely on direct contact between metal sheets and water for measurement, which easily causes polarization on the electrode surface or coating detachment due to chemical reactions. Inductive sensors measure through magnetic field coupling, and the electrodes are completely encapsulated inside high-performance materials without contact with water, so there is no consumption loss and longer service life.

Q4: Can I extend the cable myself?

A4: Yes. However, since it is an RS485 signal, it is recommended to use shielded twisted-pair wire of the same specification. If the extension distance exceeds 100 meters, please ensure sufficient power supply (considering voltage drop) and match a 120Ω resistor at the end.

Q5: What does the sensor’s IP68 rating mean in terms of underwater depth?

A5: The standard design supports long-term immersion within 10 meters water depth. If it needs to be used in deep sea or high-pressure pipelines (exceeding 0.6MPa), please specify when ordering, and we can provide customized solutions with enhanced pressure resistance.

Q6: How to determine if the sensor needs recalibration?

A6: If the measured value deviates from the laboratory analysis value by more than ±1.5% or the reading shows obvious drift, it is recommended to clean and recalibrate. In general aquaculture environments, calibration is recommended every 3-6 months.

Q7: What should I do if the 4-20mA signal output is unstable?

A7: Please first check whether the ground wire (black wire) is connected reliably and ensure that the shielding layer is grounded at one end. Also confirm that the external load resistance is within the specified range (usually ≤500Ω).

Q8: Is custom protocol or private protocol provided?

A8: The sensor adopts the standard Modbus RTU protocol by default and has extremely high versatility. For large-volume orders or specific projects, we can provide protocol customization and OEM brand labeling services.

Quality Commitment and Delivery

Yexsensor promises that every sensor undergoes strict assembly line quality inspection:

• Aging Test: 72 hours of uninterrupted aging.

• Pressure Test: Ensure encapsulation air tightness.

• Standardized Delivery: Each set includes sensor, instruction manual, certificate of conformity, and 5-meter shielded cable.

Looking for a professional salinity monitoring solution? If you need complete system design advice or bulk purchase quotes, please contact our application engineers. We will provide one-stop support from hardware selection to data acquisition.