Connecting Tubing Between Indoor And Outdoor Units - Panasonic S-12MT2U6 Installation Instructions Manual

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.
Indoor Unit Tubing Connection (
Indoor unit type
Gas tubing
Liquid 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 a torque wrench and a spanner. (Fig. 5-6)
If the flare nuts are over-tightened, the flare may be
damaged, which could result in refrigerant leakage and
cause 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.
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. (200 mm).
, ... )
1 2 n-1
12, 18 24
inch ø1/2 ø5/8
mm ø12.7 ø15.88
inch ø1/4 ø3/8
mm ø6.35 ø9.52
Indoor unit
Tube diameter
lbf·inch
ø1/4"
N·m
(ø6.35 mm)
{kgf·cm}
lbf·inch
ø3/8"
N·m
(ø9.52 mm)
{kgf·cm}
lbf·inch
ø1/2"
N·m
(ø12.7 mm)
{kgf·cm}
lbf·inch
ø5/8"
(ø15.88 N·m
mm)
{kgf·cm}
17
Torque wrench
Spanner
Outdoor unit
Tightening torque
Tube thickness
approximate
120 – 160 lbf·inch
14 – 18 N·m
0.8 mm
{140 – 180 kgf·cm}
300 – 360 lbf·inch
34 – 42 N·m
0.8 mm
{340 – 420 kgf·cm}
430 – 540 lbf·inch
49 – 61 N·m
0.8 mm
{490 – 610 kgf·cm}
590 – 710 lbf·inch
68 – 82 N·m
1.0 mm
{680 – 820 kgf·cm}
Fig. 5-6
1/32"
1/32"
1/32"
5/128"