Brazing Copper Refrigerant Pipes - Hitachi UTOPIA R32 Series Installation And Operation Manual

5.4.4 Brazing copper refrigerant pipes
Brazing is the most important job in the installation of refrigeration pipes. In the event of an
accidental leak due to negligence during the brazing process, the capillary tubes, expansion valves,
etc., will be obstructed or the compressor seriously damaged.
To guarantee correct brazing between pipe surfaces, prepare them for widening according to the
data in the following table.
!
CAUTION
• It is important to check the pipe fitting measurement as indicated in the following table.
• If a tool is used to widen the copper pipe, the dimensions indicated must be respected.
Copper pipe size (C)
Ø6.35 / Ø6.5
+0.08
-0.08
Ø9.52 / Ø9.7
+0.08
-0.08
Ø12.7 / Ø12.9
+0.08
-0.08
Ø15.88 / Ø16.1
+0.09
-0.09
Ø19.05 / Ø19.3
+0.09
-0.09
Ø22.22 / Ø22.42
+0.09
-0.09
Ø25.4 / Ø25.6
+0.12
-0.12
Ø28.58 / Ø28.78
+0.12
-0.12
Ø31.75 / Ø32.0
+0.12
-0.12
Ø38.1 / Ø38.3
+0.12
-0.12
The necessary brazing must be done by brazing, using a copper and silver alloy. Before you start
brazing, install a dry nitrogen gas injection system inside the pipes to prevent the copper from
being exposed to the air while it is subjected to high temperatures.
1 Heat the outer pipe previously to ensure the filler metal
flows more easily.
2 Heat the inner pipe evenly.
3 Rubber cap.
4 Valve with no packing.
5 High pressure pipe.
6 0.03 to 0.05 MPa (0.3 to 0.5 kg/cm
7 Reducer valve: only open the valve when gas is required.
8 Nitrogen gas flow, 0.05 m
PMEN0654 rev.0 - 12/2023
Tolerance between d1
Ød1
and C
/ /
+0.1 +0.33
0 0.07
/ /
+0.1 +0.36
0 0.10
/ /
+0.1 +0.38
0 0.12
/ /
+0.1 +0.41
0 0.13
/ /
+0.1 +0.44
0 0.16
/ /
+0.1 +0.39
0 0.11
/ /
+0.1 +0.42
0 0.08
/ /
+0.1 +0.42
0 0.08
/ /
+0.1 +0.47
0 0.13
/ /
+0.1 +0.42
0 0.08
G).
2
/h or less.
3
a
(Unit: mm)
6
8
8
8
10
10
12
12
12
14
C
5
a
20