Yexsensor delivers industrial-grade water quality sensors engineered for demanding environments.

The YEX-NHN-302 stands out with its multi-parameter capability, advanced compensation algorithms, and durable design, ensuring stable performance even in complex water matrices.

Why Choose the YEX-NHN-302 Ammonia Nitrogen Sensor?

Ammonia nitrogen (NH4-N / NH3-N) is a critical indicator of water pollution, organic waste decomposition, and treatment process efficiency. High levels are toxic to aquatic life, contribute to eutrophication, and can disrupt biological nutrient removal in treatment plants. Traditional laboratory methods are slow and labor-intensive, while many online analyzers require costly reagents. The YEX-NHN-302 offers a reagent-free ISE solution with integrated compensation for potassium ions (a major interferent), pH (which affects NH3/NH4+ equilibrium), and temperature, delivering accurate real-time data for process optimization and regulatory compliance.

Key advantages include:

• Multi-parameter integration: Simultaneous measurement of NH4+, NH3, K+, pH, and temperature in one compact sensor.

• Advanced compensation: Automatic K+ (0–1000 mg/L) and pH (4–10) compensation significantly reduces interference errors common in ammonium ISEs.

• High stability and longevity: PVC/POM construction with IP68 rating supports continuous submersion; typical electrode life of 6–12 months.

• Easy integration: RS-485 Modbus/RTU protocol for seamless connection to PLC, DCS, SCADA, or IoT systems.

• Low maintenance: Replaceable electrode components and simple two-point calibration lower total cost of ownership.

• Robust operating conditions: 0–35°C working temperature, <0.1 MPa pressure, wide pH compatibility.

This sensor enables precise control of nitrification-denitrification processes, reduces energy consumption in aeration, and protects ecosystems from nitrogen pollution.

Detailed Technical Specifications

The YEX-NHN-302 provides versatile measurement ranges suitable for various applications:

Other Specifications:

• Working Conditions: 0–35°C, <0.1 MPa

• Storage Temperature: -5–65°C

• Power Supply: 12–24 VDC

• Signal Output: RS-485 (Modbus/RTU protocol)

• Shell Material: PVC/POM

• Installation: 3/4 NPT pipe thread (immersion or inline)

• Compensation: Automatic temperature (Pt1000), pH (4–10), K+ (0–1000 mg/L)

• Calibration: Two-point calibration (K+ and pH first, then NH4+)

• Protection Class: IP68

• Measurement Principle: Ion Selective Electrode (ISE)

• Electrode Life: 6–12 months

The sensor is factory-calibrated and supports straightforward field recalibration when needed.

Application Scenarios for Multi-Parameter Ammonia Monitoring

Effective ammonia control is essential across multiple sectors. The YEX-NHN-302 delivers real-time insights that drive operational improvements.

Wastewater Treatment Plants (WWTP)

In activated sludge systems, monitor ammonia in aeration tanks to optimize nitrification (conversion of NH4+ to nitrate) and anoxic zones for denitrification. Real-time data allows precise adjustment of dissolved oxygen (DO), carbon dosing, and sludge recirculation, reducing energy use for blowers while ensuring low effluent NH4-N levels for regulatory compliance. The built-in K+ compensation improves accuracy in variable wastewater matrices.

Aquaculture and Recirculating Aquaculture Systems (RAS)

Ammonia from fish waste and uneaten feed is highly toxic, especially the un-ionized NH3 form at higher pH. Continuous monitoring in ponds, tanks, or biofilters helps maintain safe levels (<0.1–1 mg/L depending on species), triggering water exchange or biofilter adjustments to protect stock health and growth rates.

Environmental and Surface Water Monitoring

Track ammonia in rivers, lakes, and reservoirs to detect pollution from agricultural runoff or sewage discharge. Integration with telemetry systems supports long-term trend analysis and early warning for eutrophication risks.

Industrial Process Water

In food processing, chemical manufacturing, pharmaceuticals, or livestock operations, monitor ammonia in influent, process streams, or effluent to maintain product quality and meet discharge standards.

Drinking Water and Groundwater

Detect ammonia contamination from natural sources or fertilizer infiltration, ensuring treatment processes effectively remove it before distribution.

Combined Systems with Nitrate Monitoring

Pair the YEX-NHN-302 with Yexsensor nitrate sensors (such as the YEX-NON-406-S) for complete nitrogen cycle tracking—from ammonia through nitrification to nitrate and denitrification—enabling advanced biological nutrient removal (BNR) strategies.

In all scenarios, the sensor’s Modbus output facilitates centralized data collection, automated control loops, and remote monitoring, turning raw measurements into actionable process intelligence.

Installation and Electrical Connection Guidelines

Installation Notes

• Orient the sensor vertically or at an angle greater than 15 degrees from horizontal. Avoid upside-down or fully horizontal mounting to prevent air bubble entrapment or reference issues.

• Use the 3/4 NPT thread for secure immersion in tanks, channels, or flow-through cells.

• Before deployment, check for air bubbles in the membrane head. Hold the sensor vertically and shake firmly downward or tap the protective cover to release bubbles.

• The protective shell connects via M66×3 thread; users can customize mounting using the same thread.

Electrical Connection

The cable is a 4-core twisted pair shielded wire:

• Red: Power (12–24 VDC)

• Black: Ground (GND)

• Blue: 485A

• White: 485B

Verify wiring sequence carefully before powering on. For long-term immersion or exposure (including seawater environments), apply waterproof treatment to all connections and use corrosion-resistant cable. Proper sealing prevents moisture ingress and ensures signal integrity.

Maintenance and Best Practices for Reliable Operation

Activation and Daily Use

• Before first use or after storage, soak the electrode in a mixed solution of 10 mg/L ammonium ion and 10 mg/L potassium ion standard for 24 hours to activate the sensitive membrane.

• After measurements, rinse gently with distilled or deionized water. Avoid wiping the membrane; blot dry if necessary.

• For short-term storage, keep the sensing element in the protective cap. For periods longer than two weeks, store dry.

Periodic Maintenance

• Inspect terminals for dryness and cleanliness; wipe with anhydrous alcohol if contaminated and allow to dry.

• Avoid prolonged immersion in distilled water or protein-rich solutions and prevent contact with silicone grease.

• Over time, the PVC membrane may develop translucency or deposits—rinse thoroughly with distilled or deionized water.

• Monitor for measurement drift; recalibrate when errors exceed specifications.

Interference Management

Ammonium ISEs can be affected by ions with similar charge and size. The YEX-NHN-302’s built-in K+ compensation addresses the primary interferent (potassium). The manual provides a detailed interference table showing concentrations of ions (H+, Li+, Na+, K+, etc.) that may cause 10% error at different ammonium levels. In most freshwater and typical wastewater applications, compensation keeps errors low. For complex matrices, matrix-matched standards or additional pre-treatment may be considered.

Calibration Procedure

• The sensor ships factory-calibrated. Avoid unnecessary recalibration.

• Sequence: Calibrate K+ and pH first, then NH4+.

• Zero Calibration: Immerse in zero standard solution, wait 5 minutes for stability, and adjust if outside tolerance.

• Slope Calibration: Use slope standard solution similarly.

• Refer to the appendix or supporting software for detailed steps. Perform calibration under representative temperature and matrix conditions for best results.

When cleaning and calibration no longer restore performance, replace the electrode.

Integration into Monitoring and Control Systems

The RS-485 Modbus/RTU interface allows easy networking of multiple sensors. Combine with other Yexsensor probes (pH, DO, conductivity, nitrate, etc.) to create comprehensive multi-parameter stations. Low power consumption supports deployment in remote or solar-powered sites. Data feeds directly into SCADA, PLC, or cloud platforms for real-time visualization, alarms, trend analysis, and automated process control.

Frequently Asked Questions (FAQ)

Q1. What is the expected service life of the YEX-NHN-302 electrode?

Typical electrode life is 6–12 months under normal operating conditions, depending on water matrix, temperature, and maintenance frequency. The design supports cost-effective replacement.

Q2. How does the sensor handle potassium interference?

The YEX-NHN-302 includes automatic K+ compensation up to 1000 mg/L, significantly improving accuracy compared to non-compensated ammonium ISEs, especially in wastewater with variable ion composition.

Q3. Can this sensor measure free ammonia (NH3) directly?

Yes. It measures NH4+ and, with pH and temperature compensation, derives NH3 and total ammonia nitrogen values, providing critical data for toxicity assessment in aquaculture and treatment processes.

Q4. Is the sensor suitable for seawater or high-salinity applications?

It performs best in freshwater to moderately saline waters. High salinity may increase ionic interferences; evaluate site-specific conditions or consult Yexsensor for guidance.

Q5. How often should calibration be performed?

Factory calibration suffices for initial deployment. Perform periodic checks (weekly to monthly) and recalibrate when drift exceeds acceptable limits or after electrode maintenance/replacement.

Q6. Does the sensor require reagents or consumables?

No. As an ISE-based sensor, it operates reagent-free, offering lower operating costs and simpler maintenance than colorimetric or wet-chemistry analyzers.

Q7. What communication protocol is supported for industrial integration?

Standard RS-485 with Modbus/RTU protocol ensures compatibility with most PLC, DCS, and SCADA systems. Custom integration support is available.

Q8. What warranty and after-sales support does Yexsensor provide?

Yexsensor conducts rigorous 72-hour aging and stability testing. Local after-sales service is available within one year (excluding misuse). Spare parts, including electrodes and pH buffers, are supplied. Contact support for technical assistance or returns.

Summary and Next Steps

The YEX-NHN-302 Multi-Parameter Online Ammonia Nitrogen Sensor from Yexsensor represents a professional, reliable, and solution-oriented tool for modern water quality management. Its integrated compensation, multi-parameter output, durability, and ease of integration make it ideal for optimizing biological nutrient removal, protecting aquatic ecosystems, ensuring regulatory compliance, and reducing operational costs in wastewater treatment, aquaculture, and environmental applications.

Ready to improve your ammonia monitoring and nitrogen removal efficiency? Contact the Yexsensor team today for product configurations, technical consultations, demonstration units, or complete multi-parameter water quality systems. Pair it with our nitrate nitrogen sensors for full nitrogen cycle control and explore the full Yexsensor portfolio to build a robust, future-ready monitoring solution tailored to your specific needs.