245. Refrigerant Tubing5-1. Use of the Flaring MethodMany of the conventional split system air conditionersemploy the flaring method to connect refrigerant tubeswhich run between indoor and outdoor units. In thismethod, the copper tubes are flared at each end andconnected with flare nuts.5-2. Flaring Procedure with a Flare Tool(1) Cut the copper tube to the required length with atube cutter. It is recommended to cut approx. 12" to20" (30 to 50 cm) longer than the tubing length youestimate.(2) Remove burrs at the end of the copper tube with atube reamer or file. This process is important andshould be done carefully to make a good flare.(Fig. 47)When reaming, hold the tube end downward and besure that no copper scraps fall into the tube. (Fig. 48)(3) Remove the flare nut from the unit and be sure tomount it on the copper tube.(4) Make a flare at the end of copper tube with a flaretool.* (Figs. 49a and 49b)(*Use “RIDGID” or equivalent.)A good flare should have the following characteristics: inside surface is glossy and smooth. edge is smooth. tapered sides are of uniform length.5-3. Caution before Connecting Tubes Tightlya) Be sure to apply a sealing cap or water-proof tapeto prevent dust or water from getting into the tubesbefore they are used.b) Be sure to apply refrigerant lubricant to the match-ing surfaces of the flare and union before connect-ing them together. This is effective for reducing gasleaks. (Fig. 50)c) For proper connection, align the union tube andflare tube straight with each other, then screw in theflare nut lightly at first to obtain a smooth match.(Fig. 51)NOTENOTEDeburringBefore AfterFig. 47ReamerCoppertubingFig. 48Flare toolFlare nutCoppertubingFig. 49bFig. 49aApply refrigerantlubricant here and hereFig. 50Flare nutUnionFig. 510 to 0.0196"(0 to 0.5 mm)If the special R410Aflare tool is used:0.0472" (1.2 mm)If the previous flare tool(clutch-type) is used:Adjust so that the amount of tubeprotrusion is as shown in the figure.