Electrochemical Ammonia Nitrogen Sensor NH4-N Digital RS485 Water Quality Sensor

Product Specification

Ammonia nitrogen NH4-N Digital RS485 Water Quality Sensor

>>Overview

An electrochemical sensor that utilizes membrane potential to determine the activity or concentration of ions in a solution. When it comes into contact with a solution containing the target ions, a membrane potential directly related to the ion activity is generated at the interface between its sensing membrane and the solution. The ion-selective electrode functions as a half-cell (except for gas-sensing electrodes) and must be combined with an appropriate reference electrode to form a complete electrochemical cell. Under normal conditions, the potentials of the internal and external reference electrodes, as well as the liquid junction potential, remain constant. Any variation in the electromotive force of the cell fully reflects changes in the membrane potential of the ion-selective electrode, enabling its direct use as an indicator electrode for potentiometric measurement of specific ion activity in solutions. Key parameters characterizing the fundamental properties of ion-selective electrodes include selectivity, dynamic measurement range, response speed, accuracy, stability, and lifespan. The sensing membrane of an ion-selective electrode acts as a selectively permeable barrier, demonstrating only relative selectivity towards different ions.

>>Feature

▪ Digital sensor with RS-485 output, MODBUS supported.
▪ Reagent-free operation, pollution-free, cost-effective, and eco-friendly.
▪ Utilizes ion-selective method for faster response time and stable signal.
▪ Electrode housing made of PP material, withstands temperatures from 0°C to 50°C.
▪ Equipped with a dedicated high-quality four-core shielded cable for accurate and stable signal transmission.

>>Technical Parameter

Power Supply:‌ 9-36 VDC
Material:‌ Main body: PP (Polypropylene); Cable: PVC
Waterproof Rating:‌ IP68/NEMA 6P
Measurement Range:‌ 0.1-1000 mg/L (expandable)
Temperature Range: 0-50°C
Accuracy:‌ ±2.5% of measurement value; Temperature: ±0.5°C
Output:‌ MODBUS RS485
Storage Temperature:‌ 0-45°C
‌Pressure Range:‌ ≤0.3 MPa
Calibration:‌ Standard solution calibration, Comparative calibration
‌Cable Length:‌ Standard: 10 meters (extendable up to 100 meters)

>>Pre-Measurement Preparation‌

1. Remove the protective cap from the electrode tip. ‌Note:‌ Avoid touching the sensitive area with fingers.
2. Shake the electrode downward (like a thermometer) to remove internal air bubbles.
3. For new or long-unused electrodes, perform activation by soaking in ‌1 ppm standard solution for at least 24 hours‌.
4. After activation, rinse the electrode with deionized water and gently blot dry with a non-woven cloth or clean tissue. Before testing, immerse the electrode tip in deionized water for ‌5 minutes‌ with stirring. Replace the water multiple times and repeat rinsing to prevent measurement errors.

>>Calibration (Slope Determination)

1. Connect the electrode to the meter.

2. Pour ‌100 mL of deionized water‌ into a ‌150 mL beaker‌ and stir thoroughly. Set the meter to ‌mV mode‌.

3. Blot the rinsed electrode dry and immerse it in the prepared deionized water.

4. Add ‌1 mL of 1000 ppm standard solution‌ to the beaker, stir thoroughly, and record the stable reading (‌E₁‌).

5. Add ‌10 mL of the same standard solution‌ to the beaker, stir thoroughly, and record the stable reading (‌E₂‌).

6. The slope at ‌25°C‌ is calculated as ‌E₂ – E₁‌. Compare the result with the specifications to validate electrode performance.

>>Troubleshooting

If the slope deviates from the specified range:

1. Prepare freshly diluted standard solution (lowest concentration).
2. Soak the electrode in the diluted solution for ‌10 minutes‌ before testing.
3. Repeat the calibration steps.
   If the issue persists, contact the manufacturer’s technical support or replace the electrode.

>>Storage

1. ‌Short-term storage:‌ Preserve the electrode in deionized water or low-concentration standard solution (1 ppm). No reactivation is required before reuse.
2. ‌Long-term storage:‌ Rinse the electrode with deionized water, gently wipe the membrane with a non-woven cloth, dry thoroughly, and store in its original packaging. Reactivate in ‌1 mg/L standard solution, deionized water, or low-concentration solution for over 2 hours‌ before reuse.