Daikin VRV IV W+ Series Installer And User Reference Manual

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18 | Piping installationInstaller and user reference guide78RWEYQ8~14T9Y1BVRV IV water-cooled system air conditioner4P452191-1B – 2020.1018.2 Preparing water piping18.2.1 Water quality requirementsCooling water(b) andcirculation systemHot water system(c) Tendency(d)Item(a) CirculationwaterMake-upwaterCirculationwaterMake-upwaterCorrosion ScaleStandard itemspH (25°C) 6.5~8.2 6.0~8.0 7.0~8.0 ○ ○Electrical conductivity (mS/m) (25°C) <80 <30 <30 ○ ○Chloride ions (mg Cl–/l) <200 <50 <50 ○Sulfate ions (mg SO42–/l) <200 <50 <50 ○Acid consumption (pH 4.8) (mgCaCO3/l)<100 <50 <50 ○Total hardness (mg CaCO3/l) <200 <70 <70 ○Calcium hardness (mg CaCO3/l) <50 <50 ○Ionic-state silica (mg SiO2/l) <50 <30 <30 ○Reference itemsIron (mg Fe/l) <1.0 <0.3 <1.0 <0.3 ○ ○Copper (mg Cu/l) <0.3 <0.1 <1.0 <0.1 ○Sulfate ion (mg S2–/l) — ○Ammonium ion (mg NH4+/l) <1.0 <0.1 <0.3 <0.1 ○Residual chlorine (mg Cl/l) <0.3 <0.25 <0.3 ○Free carbon dioxide (mg CO2/l) <4.0 <0.4 <4.0 ○Stability index 6.0~7.0 — — ○ ○(a) These items represent typical causes of corrosion and scale.(b) In a condenser water circuit that uses a closed cooling tower, the closed circuit circulating water and make-up water MUSTmeet the water quality standards for the hot water system, and passing water and make-up water MUST satisfy those forthe circulation type cooling water system.(c) Corrosion has a tendency to occur when water temperature is high (40°C or higher), and if metals with no protectivecoating are directly exposed to water, it would be a good idea to take effective measures against corrosion such as addinga corrosion inhibitor or deaeration treatment.(d) The circle marks in the columns indicate a tendency for corrosion or scale to develop.NOTICE▪ The supply water MUST be clean tap water, industrial water or cleanunderground water. Do NOT use purified or softened water.▪ Do NOT use once-through water. It may cause corrosion.18.2.2 Water circuit requirementsINFORMATIONAlso read the precautions and requirements in the "2 General safetyprecautions" [48].