3 Piping work and refrigerant charge
Copper refrigerant pipe
SMGB0099 rev.0 - 12/2016
103
3
3.4.4 Brazing copper refrigeration 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 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.
!
C A U T I O N
•
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
Ød1
Tolerance
a
Ø6.35
+0.08
/
-0.08
Ø6.5
+0.1
/
0
+0.33
/
0.07
6
Ø9.52
+0.08
/
-0.08
Ø9.7
+0.1
/
0
+0.35
/
0.09
8
Ø12.7
+0.08
/
-0.08
Ø12.9
+0.1
/
0
+0.38
/
0.19
8
Ø15.88
+0.09
/
-0.09
Ø16.1
+0.1
/
0
+0.41
/
0.13
8
Ø19.05
+0.09
/
-0.09
Ø19.3
+0.1
/
0
+0.44
/
0.16
10
Ø22.22
+0.09
/
-0.09
Ø22.42
+0.1
/
0
+0.39
/
0.11
10
Ø25.4
+0.12
/
-0.12
Ø25.6
+0.1
/
0
+0.42
/
0.08
12
Ø28.58
+0.12
/
-0.12
Ø28.78
+0.1
/
0
+0.42
/
0.08
12
Ø31.75
+0.12
/
-0.12
Ø32.0
+0.1
/
0
+0.47
/
0.13
12
Ø38.1
+0.12
/
-0.12
Ø38.3
+0.1
/
0
+0.52
/
0.18
14
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.
!
C A U T I O N
• Do not braze on refrigerant pipes without a dry nitrogen gas injection system.
•
Otherwise, a layer of rust will form that may become detached when the refrigeration system is started, causing filter or compressor
blockages.
•
NEVER USE oxygen, acetylene or fluorocarbonated gas to replace nitrogen gas: this will cause an explosion or will generate toxic
gas.
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
2
G).
7 Reducer valve: only open the valve when gas is required.
8
Nitrogen gas flow, 0.05 m
3
/h or less.
!
C A U T I O N
Keep the nitrogen gas pressure within the indicated values. A rise in pressure in the pipe could cause an explosion.
