97
Fig. 9-7
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. 9-4)
(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. 9-5)
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.
9-2. 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 connec-
tions, or when tightening them after connecting the tubing,
be sure to use 2 monkey wrenches or spanners as
shown. (Fig. 9-6)
If the flare nuts are over-tightened, the flare may be dam-
aged, which could result in refrigerant leakage and cause
injury or asphyxiation to room occupants.
When removing or tightening the gas tube flare nut, use 2
monkey wrenches together: one at the gas tube flare nut,
and one at part A. (Fig. 9-7)
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 here and here
Fig. 9-4
Flare nut
Union
Fig. 9-5
Fig. 9-6
Indoor unit
Outdoor unit
Spanner
Torque wrench
Tube diameter
ø1/4" (6.35 mm)
ø3/8" (9.52 mm)
ø1/2" (12.7 mm)
ø5/8" (15.88 mm)
Tightening torque
(approximate)
14 – 18 N
·
m
(140 – 180 kgf
·
cm)
34 – 42 N
·
m
(340 – 420 kgf
·
cm)
49 – 61 N
·
m
(490 – 610 kgf
·
cm)
68 – 82 N
·
m
(680 – 820 kgf
·
cm)
1/32 in.
1/32 in.
1/32 in.
1/32 in.
Tube thickness
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 a mon-
key wrench with a nominal handle length of 7-7/8 in.
A
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