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Shanghai Kuosi Electronics Co., Ltd
Residual chlorine tester provides scientific basis for water quality control
Date: 2025-08-21Read: 1
In the processes of drinking water safety, swimming pool water quality management, sewage treatment, and food processing disinfection, residual chlorine is an important indicator of disinfectant residue, and its concentration directly affects the sterilization effect and human health. Too high may produce odor and irritation, while too low may not effectively inhibit microorganisms. The residual chlorine tester, as a precise tool for measuring chlorine, uses DPD colorimetric method or electrochemical sensor technology to quickly determine the content of free chlorine and total chlorine in water, providing scientific basis for water quality control. To ensure accurate and reliable measurement results, residual chlorine testers must follow standardized and rigorous operating procedures.
Step 1: Instrument inspection and preparation work
Before use, check whether the appearance of the residual chlorine tester is clean, the display screen is clear, the battery is fully charged or the power connection is normal. If it is a colorimeter, confirm that the light source is not damaged; If it is an electrode type instrument, check whether the electrode film is complete and whether the filling liquid is sufficient. Ensure that the colorimetric dish or sensor probe is clean and free of scratches and water stains.
Step 2: Reagent preparation and calibration verification
For DPD colorimetric instruments, prepare effective DPD reagent powder packs or liquid reagents. Check if the reagent is within its shelf life and avoid moisture or oxidation to prevent it from becoming ineffective. Key steps: Use standard buffer solution or residual chlorine standard solution of known concentration for instrument calibration or performance verification to ensure accurate measurement standards.
Step 3: Water sample collection and processing
Collect the water sample to be tested with a clean sampling bottle to avoid contamination. If the water sample is turbid or colored, it needs to be filtered or background compensated first to prevent interference. Test as soon as possible after sampling to avoid the natural decay of residual chlorine affecting the results.
Step 4: Add reagents and reactions (colorimetric method applicable)
Add a specified volume of water sample (such as 10mL) to the colorimetric dish, add a packet of DPD reagent, cover tightly, shake well, and let it stand in the dark for 1-3 minutes to allow free chlorine to fully react with DPD to form a red compound. If total chlorine needs to be measured, first add the first batch of reagent to measure free chlorine, then add the second batch of catalyst (such as glycine or KBr), continue the reaction and measure total chlorine.
Step 5: Measurement and Reading
Wipe the outer wall of the colorimetric dish dry, place it correctly in the instrument sample slot, and close the light shielding cover. Start the measurement program, and the instrument automatically reads the absorbance and converts it into residual chlorine concentration (mg/L or ppm). For electrochemical instruments, immerse the probe into the water sample and record the reading after the value stabilizes.
Step 6: Cleaning and Maintenance
After the test is completed, immediately clean the colorimetric dish, reagent compartment, and sensor probe with deionized water to prevent residual corrosion or blockage. When not in use for a long time, the electrode should be soaked in a specialized protective solution. Regularly calibrate and perform functional checks on instruments.