5. HOW TO PROCESS TUBING
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 file. 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. (Figs. 5-1 and 5-2)
Deburring
Before
After
Fig. 5-1
NOTE
When reaming, hold the tube end downward and be sure that
no copper scraps fall into the tube. (Fig. 5-2)
(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.
(Fig. 5-3)
Flare tool
NOTE
A good flare should have the following characteristics:
● inside surface is glossy and smooth
● edge is smooth
● tapered sides are of uniform length
Copper
tubing
Reamer
Fig. 5-2
Flare nut
Copper tubing
Fig. 5-3
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. (Fig. 5-4)
Apply refrigerant lubricant.
(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. (Fig. 5-5)
● 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.
5-2. Connecting Tubing Between Indoor and Outdoor
Units
(1) Tightly connect the indoor-side refrigerant tubing extended
from the wall with the outdoor-side tubing.
Indoor Unit Tubing Connection
Indoor unit type
Gas tubing (mm)
Liquid tubing (mm)
(2) To fasten the flare nuts, apply specified torque.
When removing the flare nuts from the tubing connections,
●
or when tightening them after connecting the tubing, be sure
to use 2 adjustable wrenches or spanners. (Fig. 5-6)
If the flare nuts are over-tightened, the flare may be
damaged, which could result in refrigerant leakage and
cause injury or asphyxiation to room occupants.
Indoor unit
16
Flare nut
Union
15
22
28
36
ø12.7
ø6.35
Torque wrench
Spanner
Outdoor unit
Fig. 5-4
Fig. 5-5
45
56
Fig. 5-6