Brazing Work - Fujitsu R407C Service Manual

6-5 PRECAUTIONS FOR INSTALLATION
1. Preparing pipes
(1) Use the designated size ( diameter & thickness )
of refrigerant pipes.
(2) Those pipes purchased locally may contain dust
inside. Please blow out the dust by dried inert gas
when using.
(3) Be careful to avoid the dust or water falling into the
pipe when performing piping process and piping
installation.
(4) When processing the pipe, make the number of
bending portion as few as possible, and the bending
radius as large as possible.
(5) To process the branch, do not use T-shaped pipe,
which causes an uneven refrigerant flow. Use the
optionally available standard branch kit.
(6) If the diameter of the required pipe is different from
the branch unit, either cut it out or use the reducer.
(7) Keep the permissible length of every piping limitation to prevent a defect or cooling/heating failure.
(8) When replacing the unit, never use piping which has been used for previous installations. Only use the new piping.
2. Flare connection
(1) Confirm that there are not scratches or waster, etc., on the flare and union surface.
(2) When using lubrication oil on the inside and outside of flare, always use small amount and must the same lubrication
oil as used in the refrigerant circuit. Use of different oil will cause the lubrication oil to deteriorate and a compressor
failure. Also too much oil may introduce water inside refrigerant circuit because the synthetic oil is highly hygroscopic.

3. Brazing work

Brazing work must be carried out while blowing dry
nitrogen gas through the pipes, so that an oxidized
layer does not form on the inner surface of the pipes.
Example) Inside state of welded pipe section
Nitrogen Gas is used
Diameter and thickness of copper pipes is shown below.
diameter (inch)
Nitrogen Gas is used but not
sufficient (Oxygen gas still exists
inside the pipe)
06-11
Nominal Outer diameter
(mm)
1/4 ø 6.35
3/8 ø 9.52
1/2 ø 12.70
5/8 ø 15.88
3/4 ø 19.05
1 1/8 ø 28.58
Separation Tube
T - tube
(Standard parts)
Pressure hose
Bello ws v alve
Rubber stopper
Nitrogen Gas is not used
Thickness
(mm)
0.8
0.8
0.8
1.0
1.0
1.2
Nitr og en gas