Panasonic WU-192ME2U9 Technical Data Manual - Page 65

5. HOW TO PROCESS TUBING Design of 2WAY VRF SYSTEM Caution Before Connecting Tubes Tightly (1) Apply a sealing cap or water-proof tape to prevent dust or water from entering the tubes before they are used. (2) Be sure to apply refrigerant lubricant to the matching surfaces of the flare and union before connecting them together. This is effective for reducing gas leaks. (Fig. 2-20) (3) For proper connection, align the union tube and flare tube straight with each other, then screw in the flare nut lightly at first to obtain a smooth match. (Fig. 2-21) Adjust the shape of the liquid tube using a tube bender at the installation site and connect it to the liquid tubing side valve using a flare. Apply refrigerant lubricant Fig. 2-20 Cautions During Brazing Replace air inside the tube with nitrogen gas to prevent copper oxide film from forming during the brazing process. (Oxygen, carbon dioxide and Freon are not acceptable.) Do not allow the tubing to get too hot during brazing. The nitrogen gas inside the tubing may overheat, causing refrigerant system 1 Union Flare nut Fig. 2-21 valves to become damaged. Therefore allow the tubing to cool when brazing. Torque wrench 2 Use a reducing valve for the nitrogen cylinder. Do not use agents intended to prevent the formation of oxide film. These agents adversely affect the refrigerant and refrigerant oil, and may Indoor unit Spanner cause damage or malfunctions. Outdoor unit 3 5-2. Connecting Tubing Between Indoor and Outdoor Units Fig. 2-22 (1) Tightly connect the indoor-side refrigerant tubing extended from the wall with the outdoor-side Tube Tightening torque, approximate Tube thickness tubing. diameter in. (mm) lbs · in. N · m {kgf · cm} inch mm 4 (2) To fasten the flare nuts, apply specified torque as at right: When removing the flare nuts from the tubing ø1/4 (ø6.35) 120 - 160 14 - 18 {140 - 180} 0.025 0.635 connections, or when tightening them after connecting the tubing, be sure to use 2 adjustable wrenches or spanners ø3/8 (ø9.52) 300 - 360 34 - 42 {340 - 420} 0.030 0.762 as shown. (Fig. 2-22) If the flare nuts are over-tightened, the flare may be ø1/2 (ø12.7) 430 - 610 49 - 61 {490 - 610} 0.035 0.889 5 damaged, which could result refrigerant leakage and cause in injury or asphyxiation to room occupants. ø5/8 (ø15.88) 590 - 710 67 - 81 {680 - 820} 0.040 1.016 For the flare nuts at tubing connections, be sure to use the flare nuts that were supplied with the unit, or else flare ø3/4 (ø19.05) 870 - 1040 99 - 118 {1000 - 1200} 0.042 1.0668 6 nuts for R410A (type 2). The refrigerant tubing that is used must be of the correct wall thickness as shown in the table at right. Because the pressure is approximately 1.6 times higher than conventional refrigerant pressure, the use of ordinary flare nuts (type 1) or thin-walled tubes may result in tube rupture, injury, or asphyxiation caused by refrigerant leakage. 7 In order to prevent damage to the flare caused by over-tightening of the flare nuts, use the table above as a guide when tightening. When tightening the flare nut on the liquid tube, use an adjustable wrench with a nominal handle length of 7-7/8" (200 mm). 8 2 - 49 9