What are the causes of the resistivity drop of ultra pure water equipment

During the operation of ultra pure water equipment, the resistivity drop is related to many factors Let's introduce the reasons for the resistivity drop of ultra pure water equipment I Problems in the system current control work current increases, and the water quality of ultra pure water equipment continues to improve However, if the current is increased after it reaches the high point, due to the excessive amount of H + and oh - ions produced by water ionization, in addition to being used for regeneration resin, a large number of surplus ions act as current carrying ions to conduct electricity At the same time, due to the accumulation and blocking of a large number of current carrying ions in the process of moving, or reverse diffusion occurs, the water quality of the produced water will decline II If the outlet water of reverse osmosis equipment is unqualified, if the salt content of raw water is high, it is recommended to use bipolar RO reverse osmosis equipment as pre desalting equipment, and the conductivity should be kept at 1-3 μ s / cm; if the CO2 content of inlet water is high, it is recommended to use degassing membrane or degassing tower to remove CO2 The pH deviates from the neutral too much, so pH adjustment is adopted to make the pH value of the influent water at 7-8 3 Iron pollution in the operation of ultra pure water equipment is the main reason for the progressive decline of its water production resistance If the common steel pipe is used in the raw water and pretreatment system without anti-corrosion treatment, the iron content in the system will increase, and the iron will become Fe (OH) 3 suspended state after being corroded The adsorption capacity of resin to iron is strong, and it will cause irreversible reaction after being adsorbed by resin In the treatment of anion and cation exchange water, the anion and cation beds will be regenerated or cleaned to remove most of the iron in the resin However, in the operation of ultra pure water equipment, there is no regeneration and cleaning, and the iron element in water will adhere to the anion, cation resin and anion, cation membrane, resulting in the decline of the working performance of components, poor water production quality, and progressive reduction of resistance value 4 Organic matter pollution: the colloid of organic matter in the water inlet of ultra pure water equipment is polluted, and the colloid of organic matter with relative molecular weight greater than 200 can only be removed by reverse osmosis If the molecular weight is less than 200, it will enter the human system This part of low molecular weight materials will be adsorbed by anion and cation exchange resin in the module on the mesh of the framework and the surface of anion and cation membrane, to intercept the displacement reaction of anion and cation and the speed of ions in water penetrating the anion and cation membrane, thus resulting in the decline of working performance and the decrease of resistivity of water production V the content of CO2 in the influent water of the pH value change system is high If the content of CO2 is more than 10ppm, the system cannot prepare ultra pure water The above is the introduction of the reasons why the resistivity of ultra pure water equipment has declined In the process of ultra pure water operation, we should try to ensure that the resistivity of ultra pure water equipment is unchanged, so as to ensure the stability of the water quality.