What are the standards and requirements for pure water for industrial ultrapure water machines?

The standards and requirements for purified water for industrial ultrapure water machines are the requirements and related standards for the quality of purified water when producing and using ultrapure water in the industrial field. Industrial ultrapure water machines are widely used in electronics, chemical, pharmaceutical and other industries, and have high water quality requirements. The following will be discussed from aspects such as water quality standards, water quality requirements, and testing methods.

I. Water quality standards

The water quality standards for industrial ultra-pure water machines are stipulated by relevant national standards and industry standards. These standards use the chemical composition, microbial content, dissolved gas and impurity content of water as evaluation indicators. The following are some common standards for purified water in industrial ultrapure water machines:

1. Conductivity: Conductivity is a key indicator of the ionic content and electrical conductivity of water. In general, industrial ultrapure water machines require the conductivity of purified water from effluent to be less than 5μS/cm.

2. TOC content: TOC (Total Organic Carbon) is an important indicator for evaluating the content of organic matter in water. TOC content is generally required to be less than 0.5ppb.

3. Bacteria and microorganisms: The number and types of bacteria and microorganisms in purified water should be as low as possible. The total number of bacteria is usually required to be less than 1 CFU/ml, and Escherichia coli and other pathogenic microorganisms cannot be detected.

4. Other impurities: In addition, industrial ultrapure water machines also require the content of dissolved gas and impurities such as sodium, potassium, iron, copper, arsenic, and nitrosamines in purified water to be as low as possible.

II. Water quality requirements

1. Removal of inorganic salts and organic matter: Industrial ultrapure water machines mainly remove inorganic salts and organic matter in water through processes such as reverse osmosis, ionization exchange and ultrafiltration. Inorganic salts mainly include sodium, potassium, magnesium, calcium, chloride ions, etc., and organic substances mainly include TOC, amine compounds, trace organic pollutants, etc. Industrial ultrapure water machines need to be able to effectively remove these harmful substances and ensure the purity of the effluent.

2. Sterilization of microorganisms: The main method for industrial ultrapure water machines to remove microorganisms is through ultraviolet irradiation and ultrafiltration membrane. Radiation sterilization can effectively kill bacteria and viruses in purified water, and ultrafiltration membrane can filter out microorganisms and macromolecular organic matter.

3. pH control: The pH value of purified water is usually between 5.5 and 7. Industrial ultrapure water machines need to be able to adjust the pH value of purified water through ionization exchange and other processes to maintain stable water quality.

4. Safety: Industrial ultra-pure water machines need to take measures to ensure water quality safety and prevent secondary pollution, such as using high-quality materials, taking anti-corrosion and anti-bacterial measures, etc.

III. Test methods

In order to ensure that the purified water produced by industrial ultrapure water machines meets standards and requirements, water quality testing is needed. Currently commonly used water quality testing items include the following aspects:

1. Conductivity detection: The conductivity of water samples can be measured through a conductivity meter to determine the ion content and purity of water.

2. TOC detection: The total organic carbon content in water can be determined by methods such as high temperature combustion oxidation or ultraviolet photometry.

3. Total number of colonies detection: Use colony counting methods such as coating method and membrane filtration method to detect the total number of colonies in purified water.

4. Chemical analysis: Through chemical analysis methods, the content of various inorganic salts and organic compounds in water can be measured, such as ion chromatography, atomic absorption spectroscopy, liquid chromatography, etc.

5. Sterilization effect testing: Test the killing effect of microorganisms in purified water through methods such as medium inoculation, subsequent culture and colony counting.

The above are the basic contents of the standards and requirements for pure water for industrial ultrapure water machines. With the continuous development of the industrial field and technological advancement, the requirements for the quality of pure water are also constantly increasing. As one of the important equipment for producing purified water, industrial ultrapure water machines require continuous improvement and innovation to meet the needs of different industries for purified water.