The calcium magnesium ion monitoring instrument, as the core equipment for water hardness testing, has a direct impact on the accuracy of the testing results and the service life of the instrument due to its standardized operation. The following systematically explains the key usage details from installation and debugging, sample processing, measurement process to maintenance and upkeep.
1、 Installation, debugging, and initial setup
1. Environmental adaptation
Choose a dry and ventilated environment, avoid direct sunlight and strong magnetic field interference;
The power supply voltage should be stable within the instrument's labeled range (± 5%), and it is recommended to equip it with an uninterruptible power supply (UPS);
Preheat the optical components for 30 minutes to achieve thermal stability during startup.
2. Reagent configuration
Strictly follow the instructions to prepare the color developer, pay attention to storing it away from light and prepare it as needed;
The standard solution should use reference materials certified by national metrology, and be sealed and refrigerated after gradient dilution.
3. Pipeline airtightness inspection
After connecting the injection tube and waste liquid tube, perform a no-load operation test to observe whether the pump pressure is stable and whether there are no visible bubbles leaking from each interface.
2、 Sample Preparation and Injection Standards
1. Filter and clarify
The water sample needs to be filtered through a 0.45 μ m membrane to remove suspended particles and prevent clogging of the colorimetric cell;
Samples with high turbidity can be centrifuged first to avoid impurities interfering with the color reaction.
2. pH adjustment
Control the pH of the sample within a specified range (usually 8-10) using a buffer solution, and add acid-base regulators when deviating;
Record the pH correction value for subsequent data compensation calculations.
3. Injection volume control
When using quantitative ring injection, it is necessary to ensure that the sample is filled with the ring to avoid residual bubbles;
Manual injection should be maintained at a constant speed to prevent baseline drift caused by sudden changes in flow rate.
3、 Key points of measurement operation and quality control
1. Calibration curve verification
Before daily testing, draw a calibration curve using standard solution, and the correlation coefficient R ² should be ≥ 0.999;
If the deviation of a certain concentration point is greater than ± 5%, it is necessary to recalibrate and investigate the cause (such as lamp source attenuation, flow pool pollution).
2. Blank deduction
Inject deionized water as a blank before each measurement, and automatically deduct the background absorbance;
When frequently changing the batch number of reagents, it is necessary to re measure the blank value.
3. Timing control of readings
After the color reaction is completed, wait for 60 seconds before reading to ensure the stability of the complex;
During continuous measurement, cleaning cycles should be spaced to prevent cross contamination.
4、 Daily maintenance and fault prevention
1. Flow path maintenance
Rinse the flow path with deionized water for 10 minutes after the daily experiment, and backwash with a dedicated cleaning solution every week;
Disassemble the circulation pool every month and inspect the quartz window panels for scratches or deposits.
2. Light source maintenance
The service life of deuterium/tungsten lamps is about 2000 hours, and they need to be replaced when the brightness is lower than 70% of the initial value;
Optical lenses should be wiped unidirectionally with wiping paper dipped in ethanol every month, and dry wiping is prohibited.
3. Consumables management
If the peristaltic pump tube hardens or cracks, it should be replaced immediately. It is recommended to replace it preventively every quarter;
The aging of the sealing ring can cause leakage, and if the O-ring is found to be deformed, it should be replaced in a timely manner.
By strictly following the above operating procedures, the data accuracy and equipment reliability of the calcium and magnesium ion monitoring instrument can be significantly improved. It is recommended to establish a standardized operating procedure (SOP) and conduct regular performance validation to ensure that the instrument is always in optimal working condition.