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5.  HOW TO PROCESS TUBING
When connecting RAC Multi outdoor unit, see Section “INSTALLATION INSTRUCTION 
SUPPLEMENT” as well.
Must ensure mechanical connections be accessible for maintenance purposes.
5-1. Connecting the Refrigerant Tubing
Use of the Flaring Method
Many of conventional split system air conditioners employ the flaring method to connect 
refrigerant tubes that run between indoor and outdoor units. In this method, the copper tubes 
are flared at each end and connected with flare nuts.
Flaring Procedure with a Flare Tool
(1)  Cut the copper tube to the required length with a tube cutter. 
It is recommended to cut approx. 30 – 50 cm longer than the 
tubing length you estimate.
(2)  Remove burrs at each end of the copper tubing with a tube 
reamer or a similar tool. This process is important and should 
be done carefully to make a good flare. Be sure to keep any 
contaminants (moisture, dirt, metal filings, etc.) from entering 
the tubing.
NOTE
When reaming, hold the tube end downward and be sure that 
no copper scraps fall into the tube. 
(3)  Remove the flare nut from the unit and be sure to mount it 
on the copper tube.
(4)  Make a flare at the end of the copper tube with a flare tool.  
NOTE
When flared joints are reused, the flare part shall be re-fabricated.
A good flare should have the following characteristics:
●  inside surface is glossy and smooth
●  edge is smooth
●  tapered sides are of uniform length
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 (ether oil) to the inside 
of the flare nut before making piping connections. This is 
effective for reducing gas leaks. 
(3)  For proper connection, align the union tube and flare tube 
straight with each other, then screw on the flare nut lightly 
at first to obtain a smooth match.
●  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.
Flare nut
Copper 
tubing
Flare tool
Apply refrigerant lubricant.
Flare nut
Union
AfterBefore
Deburring
Copper 
tubing
Reamer
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