I. Equipment Introduction
The LFS-2002(NH₃-N) is an ammonia nitrogen online water quality analyzer developed by Lihero Technology. It utilizes the colorimetric (chromogenic) principle to achieve online and automatic monitoring of ammonia nitrogen concentration in water through automatic sampling, reagent addition, mixing reaction, and colorimetric detection.
Scope of Application: Municipal water supply, sewage treatment plants, industrial wastewater discharge outlets, surface water, and groundwater monitoring.
Measurement Principle: After the sample water reacts with reagents, a colored complex is formed. Optical colorimetric detection is then performed at a specific wavelength, with the absorbance being directly proportional to the ammonia nitrogen concentration.
II. Startup Procedures
A. Pre-Startup Inspection
- Confirm that the power supply is 220V AC, 50Hz, and reliably grounded.
- Check that the reagent bottles (chromogenic agent, buffer, and distilled water) are full.
- Ensure the waste liquid bottle is empty to prevent overflow.
- Inspect the peristaltic pump tubing and colorimetric cell for air bubbles, blockages, or leaks.
B. Startup Operation
- Turn on the instrument’s power switch.
- The screen will display “System Initialization” → “Cleaning Detection Cell” (as shown in your photo).
- The system will automatically perform the following steps: Cleaning → Reagent Tubing Filling → Colorimetric Cell Emptying → Preparation for Detection.
C. Entering Measurement Mode
- After initialization is complete, the instrument enters the standby/measurement state.
- According to the set monitoring cycle (e.g., every 15 minutes/1 hour), it automatically completes sampling, reagent addition, reaction, detection, and waste discharge.
III. Calibration Methods
Regular calibration of the ammonia nitrogen analyzer is necessary to ensure data accuracy.
A. Zero Calibration
- Take distilled water or deionized water as the blank sample.
- Select “Zero Calibration” through the operation interface.
- After system operation, it will automatically clean → inject the blank water sample → measure absorbance → automatically adjust the zero point.
B. Span Calibration
- Use a standard ammonia nitrogen solution (e.g., 1.0 mg/L or 5.0 mg/L).
- Select “Span Calibration” and connect the standard solution to the sample tube.
- After system operation, the instrument compares the measured result with the standard value and automatically corrects the slope.
C. Calibration Cycle
- It is recommended to perform zero calibration once a week and span calibration once a month.
- Recalibrate immediately after significant water quality changes or reagent replacement.
IV. Common Faults and Handling
| Fault Phenomenon | Possible Causes | Handling Methods |
|---|---|---|
| Startup stuck at “System Initialization” | Air bubbles in the tubing, improperly installed peristaltic pump tubing | Check the pump tubing, remove air bubbles, and reinstall |
| High measured values | Contaminated colorimetric cell, deteriorated reagents | Clean the colorimetric cell and replace the reagents |
| Low measured values | Aged light source, insufficient reagent concentration | Check the light source and replace the reagents |
| Inability to sample | Blocked sampling tubing or malfunctioning solenoid valve | Clean the tubing and check the solenoid valve operation |
| Screen alarm “No light signal in the colorimetric cell” | Damaged bulb or faulty photovoltaic cell | Replace the light source or photovoltaic cell |
| Large data fluctuations | Aged pump tubing, unstable reagent ratio | Replace the peristaltic pump tubing and check the reagent concentration |
V. Daily Maintenance
A. Before Each Startup
- Check the liquid levels in the reagent and waste liquid bottles.
- Inspect the pump tubing and valves for normal operation.
B. Weekly
- Perform zero calibration once.
- Clean the colorimetric cell and tubing.
C. Monthly
- Perform span calibration once.
- Check for aging of the peristaltic pump tubing (generally replace every 3-6 months).
D. Annually
- Replace the light source and key consumables.
- Conduct comprehensive calibration and maintenance.
VI. Safety Precautions
- The reagents contain chemicals. Wear protective gloves during operation.
- Collect the waste liquid and avoid direct discharge into the environment.
- If the instrument is shut down for more than one week, perform a cleaning procedure to prevent reagent crystallization and tubing blockage.