Caution Before Connecting Tubes Tightly; Tubing Connections - Panasonic CU-3KS19NBU Technical & Service Manual

NOTE
When reaming, hold the tube end downward and be sure that
no copper scraps fall into the tube. (Fig. 9)
(3) Remove the flare nut from the unit and be sure to mount
it on the copper tube.
(4) Make a flare at the end of copper tube with a flare tool.*
(Figs. 10 and 11)
(*Use "RIDGID" or equivalent.)
NOTE
A good flare should have the following characteristics:
inside surface is glossy and smooth.
edge is smooth.
tapered sides are of uniform length.

3-4. Caution before Connecting Tubes Tightly

a) Be sure to apply a sealing cap or water-proof tape to
prevent dust or water from getting into the tubes before
they are used.
b) 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. 12)
c) 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. 13)

3-5. Tubing Connections

a) Temporary connection:
Screw in 3 – 5 turns by hand. (Fig.14)
b) To fasten the flare nuts, apply specified torque as:
Table 4
Tube Dia. Nut
1/4" (6.35 mm) 21/32" (17 mm)
3/8" (9.52 mm) 7/8" (22 mm)
1/2" (12.70 mm) 1-1/32" (26 mm)
5/8" (15.88 mm) 1-5/32" (29 mm)
Tightening Torque
Approx. 120 – 160 lbs·in (140 – 180 kgf·cm)
Approx. 300 – 360 lbs·in (340 – 420 kgf·cm)
Approx. 430 – 480 lbs·in (490 – 550 kgf·cm)
Approx. 590 – 710 lbs·in (680 – 820 kgf·cm)
Service valve on
narrow tube side
Service valve on
wide tube side
17
Fig. 9
If the special R410A
flare tool is used:
0 to 0.0196"
(0 to 0.5 mm)
Fig. 10
Flare tool
Fig. 11
Apply refrigerant
lubricant here and here
Fig. 12
Union
Fig. 13
D
C
B
A
Fig. 14
Copper
tubing
Reamer
If the previous flare tool
(clutch-type) is used:
0.0472" (1.2 mm)
Adjust so that the amount of tube
protrusion is as shown in the figure.
Flare nut
Copper
tubing
Flare nut
Apply the provided labels
to the indoor and outdoor
unit tubing connectors to
prevent errors in
connections.