Daikin VRV IV W+ Series Installer And User Reference Manual

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18 | Piping installationInstaller and user reference guide87RWEYQ8~14T9Y1BVRV IV water-cooled system air conditioner4P452191-1B – 2020.10▪ When brazing, blow through with nitrogen to prevent creation of large quantitiesof oxidised film on the inside of the piping. This film adversely affects valves andcompressors in the refrigerating system and prevents proper operation.▪ Set the nitrogen pressure to 20 kPa (0.2 bar) (just enough so it can be felt on theskin) with a pressure-reducing valve.a b c d effa Refrigerant pipingb Part to be brazedc Tapingd Manual valvee Pressure-reducing valvef Nitrogen▪ Do NOT use anti-oxidants when brazing pipe joints.Residue can clog pipes and break equipment.▪ Do NOT use flux when brazing copper-to-copper refrigerant piping. Use phosphorcopper brazing filler alloy (BCuP), which does not require flux.Flux has an extremely harmful influence on refrigerant piping systems. Forinstance, if chlorine based flux is used, it will cause pipe corrosion or, inparticular, if the flux contains fluorine, it will deteriorate the refrigerant oil.▪ Always protect the surrounding surfaces (e.g. insulation foam) from heat whenbrazing.18.3.9 Using the stop valve and service portTo handle the stop valveTake the following guidelines into account:▪ Make sure to keep the appropriate stop valves open during operation. In case ofheat pump system, the gas suction stop valve remains in the closed position.▪ The gas and liquid stop valves are factory closed.▪ The figures below show the name of each part required in handling the stopvalve.adcba Service port and service port coverb Stop valvec Field piping connectiond Stop valve covera bcdea Service port