Introduction to the storage methods for pure water produced by pure water equipment in the chemical industry

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　　What are the methods for storing the pure water produced by ultra-pure water equipment, given that this leads to a decrease in its resistivity? Experimental data show that the duration of exposure to air affects the change in resistivity, as follows: after 1 minute of contact with air, the resistivity decreases by 3–4 MΩ·m. 　　When in contact with air for more than 3 minutes, the resistivity drops to 2 MΩ·m. 　　These data are valid for ultrapure water with a resistivity of 15 MΩ·m or higher. 　　Methods for preventing ultra-pure water from coming into contact with air 1. Nitrogen inflation method: Nitrogen is introduced above the water surface in the tank to maintain positive pressure and prevent air from coming into contact with the water surface. 　　2. Film bag method: A super-thin film is placed on the surface of the water in the tank; it can rise and fall with the water level, thereby reducing contact with air. 　　3. Floating roof method: Panels with a density lower than that of water are used to float on the water’s surface, while elastic materials are employed to fill the gaps between the floating roof and the tank. This reduces air contact.