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6. Pipe work
(3) Tightening connections
1. Adjust the fl are nut at the center of the connecting pipe and
suffi ciently tighten it manually, then fi x it with a spanner
and tighten with a torque wrench as shown in Figure. 6-2.
2. Always use a double spanner, as shown in Figure. 6-2, for
loosening and tightening fl are nuts on the gas side valve.
Using a single spanner does not provide suffi cient torque
for tightening.
Use a single spanner for loosening and tightening of fl are
nuts on the liquid side valve.
Outer diameter of
copper pipe
6.35 mm
9.52 mm
12.7 mm
15.88 mm
19.05 mm
1. Do not use a spanner on the stem cap.
The valve may be damaged.
2. If excessive torque is applied, the nut may be
damaged under certain installation conditions.
3. When all pipe connections have been installed, be sure to
use nitrogen to conduct a gas leak test.
• The pressure in an R410 system is 1.6 times the pressure in an
R22 system.
Accordingly, ensure that the flare pipe connections connecting
to the cooler and condensing unit are securely tightened with
a torque wrench using the stated tightening torque. Improperly
tightened connections could lead to gas leaks and damage to
the refrigeration cycle.
Do not applying refrigerating oil to the fl are surface.
(Oil may cause slipping and lead to excessive torque
(4) Intake pipe
1. Apply insulation work (refrigeration: 25 mm thick, freezing:
50 mm thick) to the intake pipe and do not use a pipe
interlinked with the liquid pipe. (Figure. 6-3)
2. The intake pipe should always have a down grade (1/200).
Also install an oil trap at an upright portion of the intake
pipe.
(5) Liquid pipe (make sure not to generate fl ushing gas)
1. If used in a multi-branch cycle, install the branching pipe
in the direction of gravity in order to always supply a full
amount of refrigerant to the expansion valve. (Figure. 6-4)
2. When the liquid pipe is upright, a pressure loss of
approximately 0.012 MPa per meter occurs. Therefore,
take care to always supply extra cooling to compensate for
this loss.
3. If the liquid pipe is expected to be heated by another
heating source, perform additional insulation work. (This
includes direct exposure to sunlight, and being installed
near heat sources like discharge pipes and boilers)
(continued)
Flare nut tightening torque
14 to 18 N∙m
34 to 42 N∙m
49 to 61 N∙m
68 to 82 N∙m
100 to 120 N∙m
Caution
application)
(Figure. 6-2)
Stem cap
Loosen
(Figure. 6-3)
Prohibited
(Figure. 6-4)
Flow of
refrigerant
18
Service valve
Tighten
Flare nut
Insulation
Liquid pipe
Intake pipe
Branch
Direction
of gravity
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