13
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 match-
ing surfaces of the flare and union before connect-
ing 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 narrow tube (liquid tube)
using a tube bender at the installation site and
connect it to the narrow tubing side (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 for-
mation 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 Out-
door Units
(1) Tightly connect the indoor-side refrigerant tubing
extended from the wall with the outdoor-side tub-
ing.
(2) To fasten the flare nuts, apply specified torque as
at right:
●
When removing the flare nuts from the tubing con-
nections, or when tightening them after connecting
the tubing, be sure to use 2 monkey 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 occu-
pants.
●
When removing or tightening the wide tube flare
nut, use 2 monkey wrenches together: one at the
wide tube flare nut and one at part A.(Fig. 5-7)
●
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 refriger-
ant 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. 5-4
Flare nut
Union
Fig. 5-5
Fig. 5-6
Indoor unit
Outdoor unit
Spanner
Torque wrench
Tube diameter
φ
6.35 (1/4")
φ
9.52 (3/8")
φ
12.7 (1/2")
φ
15.88 (5/8")
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)
0.8 mm
0.8 mm
0.8 mm
1.0 mm
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 asphyxi-
ation 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 narrow tube,
use a monkey wrench with a nominal handle length
of 200 mm.
A
Fig. 5-7
