Daikin FXHQ-M Engineeiring Data page 24

EDUS39-600-F5
6-1 GENERAL INSTRUCTIONS
• For refrigerant pipe of outdoor units, see the installa-
tion manual attached to the outdoor unit.
• Execute thermal insulation work completely on both
sides of the gas pipe and the liquid pipe or a water leak
may occur.
.
(The temperature of the gas pipe can reach up to
approximately 250°F, so use insulation pipe cover
that is sufficiently resistant.)
• In cases where the temperature and humidity of the
refrigerant pipe sections might exceed 86°F or RH
80%, reinforce the thermal insulation (3/4 in. or thicker)
or condensate may form on the surface of the insula-
tion pipe cover.
Before refrigerant pipe work, check which type of
refrigerant is used. Proper operation is not possible if
the types of refrigerant are not the same.
6-2 CONNECTING THE REFRIGERANT PIPE
• Ensure outdoor unit is charged with refrigerant.
• Use copper alloy seamless pipes.
• Be sure to use both a spanner and torque wrench together,
as shown in the drawing, when connecting or disconnect-
ing pipes to/from the unit. (Refer to Fig. 13)
• Refer to Table 2 to determine the proper tightening torque.
• Refer to Table 2 for the dimensions of flare shape.
• When connecting the flare nut, coat the flare section (both
inside and outside) with ester oil or ether oil, rotate three or
• four times first, then screw in. (Refer to Fig. 14)
Torque wrench
Flare nut
• Use the flare nut include with the main body of the unit.
CAUTION
• Oil must not adhere to any equipment other than a flare. If
oil adheres to resin or other parts, deterioration may occur..
Ester oil or ether oil.
FXHQ-M
Pipe union
Spanner
Fig. 13
Fig. 14
Table 2
Pipe size Tightening
(in.) torque (ft.lbf)
φ1/4
10.4–12.7
φ3/8
24.1–29.4
φ1/2
36.5–44.5
φ5/8
45.6–55.6
CAUTION
• Overtightening may damage the flare and cause a refriger-
ant leakage.
Not recommended but in case of emergency
You must use a torque wrench but if one is not available,
you can use the following installation method:
When you keep tightening the flare nut with a spanner, there is
a point where the tightening torque suddenly increases. From
that position, further tighten the flare nut the angle shown
below:
Table 3
Pipe size (in.) Further tightening angle Recommended arm length of tool (in.)
φ1/4
60 to 90 degrees
φ3/8
60 to 90 degrees
φ1/2
30 to 60 degrees
φ5/8
30 to 60 degrees
After the work is finished, make sure to check that
there is no gas leak.
6-3 BRAZING REFRIGERANT PIPING
• Do not use flux when brazing refrigerant pipe. Use phos-
phor copper brazing filler metal (BCuP) which does not
require flux.
• Flux has an extremely negative effect on refrigerant piping
systems. For instance, if chlorine based flux is used, it will
cause pipe corrosion. If the flux contains fluorine, it will
damage the refrigerant oil.
• Before brazing local refrigerant pipe, nitrogen gas shall be
blown through the pipe to expel air from the pipe.
If brazing is done without nitrogen gas blowing, a large
amount of oxide film develops inside the pipe which can
cause system malfunction.
• When brazing the refrigerant pipe, only begin brazing after
having carried out nitrogen substitution or while inserting
nitrogen into the refrigerant pipe. Once this is done, con-
nect the indoor unit with a flared or a flanged connection.
• Nitrogen should be set to 2.9 psi with a pressure-reducing
valve if brazing while inserting nitrogen into the pipe.
(Refer to Fig. 15)
Refrigerant pipe
Part to be
brazed
Nitrogen
Installation
Flare dimen-
sions A Flare shape (in.)
(in.)
0.342–0.358
0.504–0.520
R0.016-0.031
0.638–0.654
0.760–0.776
Approx. 5 7/8
Approx. 7 7/8
Approx. 9 13/16
Approx. 11 13/16
Pressure-reducing
valve
Taping
hands valve
Nitrogen
Fig. 15
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