Chlorine meter calibration

The residual chlorine meter is one of the specialized devices used to measure the chlorine content in water. Chlorine is a compound often used to disinfect water, but if the content of this substance exceeds the allowable level, it will cause toxic substances. This will directly affect human health.

Chlorine is one of the most commonly used chemicals to treat domestic water, and can cause many negative health effects if in excess. Residual chlorine content in domestic water needs to be strictly controlled. Besides, it is necessary to find a way to overcome this excess in the most effective way to protect users' health.

What is the standard concentration of chlorine in water?

According to QCVN01:2009/BYT(National Technical Regulations on Drinking Water Quality) regulates the residual chlorine content in water to be 0.3 - 0.5mg/l. However, in reality, tap water sources in Vietnam greatly exceed this standard threshold.
According to the Ministry of Natural Resources and Environment, the maximum chlorine concentration standard in domestic water is 1.0 mg/liter and the safest index will be about 0.2 mg/liter. The maximum allowable limit is 1.0 mg/liter.

Because the right chlorine concentration ensures the best effectiveness in inactivating bacteria and viruses. thereby ensuring that the washing water system does not affect users' health.

When realizing the important impact of chlorine on the environment. Requirements for using chlorine are becoming more and more stringent. People are always looking for ways to use chlorine to disinfect without harming health and the environment. Since then, the Chlorine meter was born and performed this task very well.

- In medicine: wound disinfection, anesthesia.
- In chemistry: paints, solvents, foaming agents, pesticides, antifreeze chemicals,...
- In agriculture: disinfect ponds and lakes, kill bacteria in the water environment, oxidize organic materials and pathogens in breeding production.

- Measurement standards

• Chlorine standard tube 50-75 mg/L
• Standard tube of Chlorine 100mg/

- Other measuring devices

• Distilled water, cleaning paper, glassware,...
• Cuvette set with detector, usually 10ml
• Reagents

• Temperature: (25 ± 2) ºC.
• Humidity: (40 ÷ 80) %RH

- The UUT and standard media should be placed in the calibration environment for not less than 30 minutes to stabilize the temperature.
- Prepare reagents corresponding to each model of UUT and blank samples according to the manufacturer's instructions for use.
- Prepare at least 03 standard solutions with concentrations evenly distributed over the measuring range of the UUT, or appropriate standard concentrations according to customer requirements.

- The UUT must have a label with parameters such as engine number, place of manufacture, Max, graduation value, etc.

- The UUT must have all necessary parts and accessories.

- The UUT indicator must be clear and readable accurately.

• Start the UUT. During the start-up process, the UUT must operate normally.
• For UUT with a self-calibration function, the UUT must perform this function. That function should work normally.
• For UUT without a self-calibration function, it is required to have a sealing mechanism to prevent the correct adjustment of the UUT.

- Choose a comparison method
- Select the number of iterations
- Conduct repeated measurements
- Calculate and process data

- Measurement testing is performed by comparing the direct measurement results of the standard solution using a UUT and the certified Chlorine value of that standard solution.
- Conduct Cal according to UUT's instructions (if any).

- How to prepare blank samples and standard samples, how to add reagents, wait time for stabilization, and how to read values on the LCD according to the manufacturer's instructions.

- At each measurement value, the cuvette containing the standard solution to be tested must be rinsed at least 3 times with the corresponding standard solution.
- Check accuracy and repeatability
- Estimate measurement uncertainty

- After calibration, the Chlorine meter is stamped and issued a calibration certificate with the calibration results.
- Recommended calibration cycle: 01 year