Panasonic U-8MF1E8 Mode D'emploi page 19

3WAY̲ECO-i̲inst̲eng̲Book.indb 31
5. HOW TO PROCESS TUBING
The liquid tubing side is connected by a flare nut, and the gas
tubing side is connected by brazing.
5-1. Connecting the Refrigerant Tubing
Use of the Flaring Method
Many of conventional split system air conditioners employ the
flaring method to connect refrigerant tubes which run between
indoor and outdoor units. In this method, the copper tubes are
flared at each end and connected with flare nuts.
Flaring Procedure with a Flare Tool
(1) Cut the copper tube to the required length with a tube
cutter. It is recommended to cut approx. 30 – 50 cm longer
than the tubing length you estimate.
(2) Remove burrs at the end of the copper tube with a tube
reamer or file. This process is important and should be done
carefully to make a good flare.
Be sure to keep any contaminants (moisture, dirt, metal
filings, etc.) from entering the tubing. (Figs. 5-1 and 5-2)
Deburring
Before After
Copper
tubing
Reamer
Fig. 5-1
N OTE
When reaming, hold the tube end downward and be sure that
no copper scraps fall into the tube. (Fig. 5-2)
(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 the copper tube with a flare tool.
(Fig. 5-3)
Flare nut
Copper
tubing
Flare tool
N OTE
A good flare should have the following characteristics:
● inside surface is glossy and smooth
● edge is smooth
● tapered sides are of uniform length
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 (ether oil) to the
inside of the flare nut before making piping connections.
This is effective for reducing gas leaks. (Fig. 5-4)
Apply refrigerant lubricant
(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)
Flare nut
Union
● Adjust the shape of the liquid tube using a tube bender at the
Fig. 5-2
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
Fig. 5-3
malfunctions.
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SUPPLEMENT
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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 (Fig. 5-6).
●
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. (Fig. 5-6)
If the flare nuts are over-tightened, the flare may be damaged,
which could result refrigerant leakage and cause injury or
asphyxiation to room occupants.
Torque wrench
Indoor unit
Outdoor unit
Fig. 5-4
●
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 below.
Tightening torque
Tube diameter
(approximate)
14 – 18 N · m
ø6.35 (1/4")
(140 – 180 kgf · cm)
34 – 42 N · m
ø9.52 (3/8")
(340 – 420 kgf · cm)
Fig. 5-5
49 – 61 N · m
ø12.7 (1/2")
(490 – 610 kgf · cm)
68 – 82 N · m
ø15.88 (5/8")
(680 – 820 kgf · cm)
100 – 120 N · m
ø19.05 (3/4")
(1000 – 1200 kgf · cm)
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 narrow tube, use an
adjustable wrench with a nominal handle length of 200 mm.
5-3. Insulating the Refrigerant Tubing
Tubing Insulation
● Thermal insulation must be applied to all units tubing,
including distribution joint (purchased separately).
* For gas tubing, the insulation material must be heat
resistant to 120°C or above. For other tubing, it must be
heat resistant to 80°C or above.
Insulation material thickness must be 10 mm or greater.
If the conditions inside the ceiling exceed DB 30°C and RH
70%, increase the thickness of the suction and gas tubing
insulation material by 1 step.
Two tubes arranged together
Liquid tubing
Spanner
Fig. 5-6
Insulation
Three tubes arranged together
Cosmetic
(finishing) tape
Discharge tubing
Tube thickness
0.8 mm
0.8 mm
0.8 mm
Insulation
1.0 mm
Four tubes arranged together
Cosmetic
1.0 mm
(finishing) tape
Discharge tubing
Balance tubing
Insulation
CAUTION
If the exterior of the outdoor unit valves has been finished
with a square duct covering, make sure you allow sufficient
space to use the valves and to allow the panels to be
attached and removed.
Taping the fl are nuts
Wind the white insulation tape around the flare nuts at the gas
tube connections. Then cover up the tubing connections with
the flare insulator, and fill the gap at the union with the supplied
black insulation tape. Finally, fasten the insulator at both ends
with the supplied vinyl clamps. (Fig. 5-8)
Sealer (supplied)
Insulation tape (white) (supplied)
Unit side
insulator
Flare nut
Vinyl clamps (supplied)
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Gas tubing
Suction tubing
Liquid tubing
Suction tubing
Liquid tubing
Fig. 5-7
Flare insulator (supplied)
Tube insulator
(not supplied)
Heat resistant
120°C or above
Fig. 5-8