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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. 5-4)
(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. 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.
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 valves to
become damaged. Therefore allow the tubing to
cool when brazing.
● 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 cause
damage or malfunctions.
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.
(2) To fasten the flare nuts, apply specified torque as at
right:
● 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 as shown. (Fig. 5-6)
If the flare nuts are over-tightened, the flare may be
damaged, which could result refrigerant leakage and
cause in injury or asphyxiation to room occupants.
● For the flare nuts at tubing connections, be sure to use
the flare nuts that were supplied with the unit, or else
flare 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.
Apply refrigerant
lubricant
Fig. 5-4
Union
Fig. 5-5
Torque wrench
Indoor unit
Fig. 5-6
Tightening torque,
Tube diameter
approximate
120 – 160 lbs
ø1/4" (ø6.35 mm)
(140 – 180 kgf
300 – 360 lbs
ø3/8" (ø9.52 mm)
(340 – 420 kgf
430 – 480 lbs
ø1/2" (ø12.7 mm)
(490 – 550 kgf
590 – 710 lbs
ø5/8" (ø15.88 mm)
(680 – 820 kgf
870 – 1040 lbs
ø3/4" (ø19.05 mm)
(1000 – 1200 kgf
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.
● 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".
29
Flare nut
Spanner
Outdoor unit
Tube thickness
·
in
t1/32"
·
cm)
(0.8 mm)
t1/32"
·
in
·
(0.8 mm)
cm)
·
in
t1/32"
·
cm)
(0.8 mm)
·
in
t5/128"
·
cm)
(1.0 mm)
over t5/128"
·
in
·
(over 1.0 mm)
cm)
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