Service & Technical Guide

1-119
1. Specifications
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
fl are and union before connecting them together. This is effective for
reducing gas leaks. (Fig. 1-113)
(3) For proper connection, align the union tube and fl are tube straight with
each other, then screw on the fl are nut lightly at fi rst to obtain a smooth
match. (Fig. 1-114)
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 fl are.
Cautions During Brazing
Replace air inside the tube with nitrogen gas to prevent copper
oxide fi lm 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 fi lm.
These agents adversely affect the refrigerant and refrigerant oil,
and may cause damage or malfunctions.
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 fl are nuts, apply specifi ed torque as shown at right.
When removing the fl are nuts from the tubing
connections, or when tightening them after
connecting the tubing, be sure to use 2 adjustable
wrenches or spanners. (Fig. 1-115)
If the fl are nuts are over-tightened, the fl are may
be damaged, which could result in refrigerant
leakage and cause injury or asphyxiation to
room occupants.
When removing or tightening the gas tube fl are
nut, use 2 adjustable wrenches together: one at
the gas tube fl are nut, and one at part A.
(Fig. 1-116)
For the fl are nuts at tubing connections, be
sure to use the fl are nuts that were supplied
with the unit, or else fl are 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.
Because the pressure is approximately 1.6 times higher
than conventional refrigerant pressure, the use of ordinary
fl are 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 fl are caused by
over-tightening of the fl are nuts, use the table above
as a guide when tightening.
When tightening the fl are nut on the liquid tube, use an
adjustable wrench with a nominal handle length of 7-7/8 in.
Fig. 1-113
Apply refrigerant
lubricant
Fig. 1-114
Flare nut
Union
Fig. 1-115
Indoor unit
Outdoor unit
Spanner
Torque wrench
Fig. 1-116
A
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)
120 – 160 in.lbs
(140 – 180 kgf
·
cm)
300 – 360 in.lbs
(340 – 420 kgf
·
cm)
430 – 480 in.lbs
(490 – 550 kgf
·
cm)
590 – 710 in.lbs
(680 – 820 kgf
·
cm)
t0.032
t0.032
t0.032
t0.04
Tube thickness
(in.)
1
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