Brazing Work - Hitachi RAS-H(V)RNME-AF Service Manual

3 Piping work and
refrigerant charge

Brazing work

C A U T I O N
• Use nitrogen gas for blowing during pipe brazing. If oxygen, acetylene or fluorocarbon gas is used, it will cau-
se an explosion or poisonous gas.
• A rust coating will appear inside of tubes if no nitrogen gas blowing is performed during brazing work. This
film will be flecked off after operation and will circulate in the circuit, resulting in clogged expansion valves,
etc, and the compressor will be affected.
• Use a reducer valve when nitrogen gas blowing is performed during brazing. The gas pressure should be
maintained within 0.03 to 0.05 MPa. If excessively high pressure is applied to a pipe, it will cause an explosion.
Copper pipe size
+0.08
Ø6.35
-0.08
+0.08
Ø9.53
-0.08
+0.08
Ø12.7
-0.08
+0.09
Ø15.88
-0.09
+0.09
Ø19.05
-0.09
+0.09
Ø22.22
-0.09
+0.12
Ø25.4
-0.12
A basic brazing method is shown below.
No.
1 Pre-heat the outer tube for better flowing of the filler metal
2 Heat inner side tube evenly
3 Rubber plug
4 Packless valve
5 High pressure hose
6 0.03 to 0.05 MPa (0.3 to 0.5 Kg/cm
7 Reducer valve: open this valve only when the gas is needed
8 Nitrogen gas flow 0.05 m
66
SMGB0070 rev.1 - 08/2011
Ød1 Gap
+0.1 0.33
Ø6.5
0 0.07
+0.1 0.35
Ø9.7
0 0.09
+0.1 0.38
Ø12.9
0 0.19
+0.1 0.41
Ø16.1
0 0.13
+0.1 0.44
Ø19.3
0 0.16
+0.1 0.39
Ø22.42
0 0.11
+0.1 0.42
Ø25.6
0 0.08
Description
G)
2
/h or smaller
3
a
6
8
8
8
10
10
12