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7
2.
Refrigerant piping
CAUTION
• Use the flare nut fixed to the main unit to prevent it from cracking and deteriorating from age.
• To prevent gas leakage, apply refrigeration oil only to the inner surface of the flare. (Use refrigeration oil for R410A.)
• Use torque wrenches when tightening the flare nuts to prevent damage to the flare nuts and gas leakage.
Align the centers of both flares and tighten the flare nuts 3 or 4 turns by hand. Then tighten them fully with the torque
wrenches.
Do not apply refrigeration
oil to the outer surface.
Flare nut
Apply refrigeration oil to
the inner surface of the
flare.
Do not apply refrigeration oil to
the flare nut to avoid tightening
with excessive torque.
[Apply oil]
Torque wrench
Piping union
Flare nut
Spanner
[Tighten]
Flare nut tightening torque
Gas side
Liquid side
1/4 inch (6.4mm)
10.4-12.7ft • lbf
(14.2-17.2N • m)
24.1-29.4ft • Ibf
(32.7-39.9N • m)
3/8 inch (9.5mm)
2-1. Caution on piping handling
1) Protect the open end of the pipe against dust and moisture.
2) All pipe bends should be as gentle as possible. Use a pipe bender
for bending.
Wall
If no flare cap is
available, cover
the flare mouth
with tape to keep
dirt or water out.
Be sure to
place a cap.
Rain
2-2. Selection of copper and heat insulation materials
• When using commercial copper pipes and fittings, observe the following:
1) Insulation material: Polyethylene foam
Heat transfer rate: 0.041 to 0.052W/mK (0.024 to 0.030Btu/fth°F (0.035 to
0.045kcal/mh°C))
Be sure to use insulation that is designed for use with HVAC Systems.
Gas pipe
Liquid pipe
Gas pipe
insulation
Liquid pipe
insulation
Finishing tape
Drain hose
Inter-unit wire
2) Be sure to insulate both the gas and liquid piping and to provide insulation
dimensions as below.
Gas side
Liquid side
Gas pipe thermal
insulation
Liquid pipe thermal
insulation
O.D. 3/8 inch
(9.5mm)
O.D. 1/4 inch
(6.4mm)
I.D. 15/32-19/32 inch
(12-15mm)
I.D. 5/16-13/32 inch
(8-10mm)
Minimum bend radius
Thickness 13/32 inch (10mm) Min.
1-3/16 inch (30mm) or more
Thickness 0.031 inch (0.8mm) (C1220T-O)
3) Use separate thermal insulation pipes for gas and liquid refrigerant pipes.
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