The laboratory ultrapure water machine provides more benefits and convenience. Compared with the electric distilled water device or buying water outside, this has been recognized by the majority of chemical analysts. However, as the basic equipment of the laboratory, although many technicians are using ultra-pure water machine, they do not know much about it, so they often have misunderstandings in purchasing. In view of how to choose a suitable ultrapure water machine, the following factors are summarized.
 
I. Water consumption　　
At present, the water production capacity of ultrapure water machines on the market is generally 5-45 liters/hour. Users should choose the specifications of the ultrapure water machine according to the actual water consumption, and generally follow the principle of double relationship. That is, if the water consumption is 20 liters/day, choose an ultrapure water machine with a specification of 10 liters/hour. If the specification is too small, the consumables of the ultrapure water machine will be consumed quickly. If the specification is too large, it will lead to waste. If the concentrated water consumption is large, a larger pure water bucket should be selected, otherwise the fresh water cannot keep up with it.
 
II. Water quality　　
National laboratory standard water is divided into first, second, and third grades, but most laboratories just use two kinds of water. One is third-grade water, such as distilled water, which is used for cleaning glassware, and the other is first-grade water, which is mainly used for chemical analysis or precision instrument analysis like liquid phase and atomic absorption. Users should choose the grade of ultrapure water machine according to actual water quality requirements. The ultrapure water machine that uses tap water as the water source has two (two types of water quality) outlets. One is pure water, and the other is first-grade water, namely ultra-pure water (strictly speaking, the resistance of the first-grade water is greater than 10 megohms, while the resistance of ultra-pure water is greater than 18 megohms).
 
III. Source water quality　　
When purchasing an ultrapure water machine, users must provide the manufacturer with the water quality of the source water, such as high silt content, high hardness, and groundwater. The process of the ultrapure water machine is determined according to the quality of the source water. If there is a lot of silt, it is necessary to add a pretreatment device, while if the hardness is high, a softening device should be added, and if the salt content is high, the two-stage reverse osmosis process should be used. If you choose an ultrapure water machine that uses pure water as the water source, you only need to provide water quality requirements and water consumption.