5-2. Connecting Tubing Between Indoor And; Outdoor Units - Panasonic U-72MF1U9 Installation Instructions Manual

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 in.
33
Flare nut
Spanner
Outdoor unit
Tube thickness
· inch t1/32"
· cm)
(0.8 mm)
· t1/32"
inch
·
cm) (0.8 mm)
· t1/32"
inch
· (0.8 mm)
cm)
· t5/128"
inch
·
cm) (1.0 mm)
· inch over t5/128"
· cm)
(over 1.0 mm)