What are the grades of national laboratory standard water?
What is the classification of standard water for national laboratories? There are three kinds of water quality: first grade water, second grade water and third grade water, but most laboratories can use two kinds of water quality, one is three grade water, such as distilled water, used for cleaning glassware, etc. It is mainly used for chemical analysis or precision instrument analysis such as liquid phase and atomic absorption. The customer should select the grade of ultrapure water equipment according to the actual water quality requirements. Ultra-pure water machines with tap water as the water source have two (two water quality) outlets, one is pure water, that is, three-stage water; the other is first-grade water, that is, ultra-pure water (strictly speaking, first-grade water) The resistance is greater than 10 megohms, while the resistance of ultrapure water is greater than 18 megohms. The above is the classification of the standard water used in national laboratories.