OPERATING INSTALLATION MANUAL FOR AHU-KIT UNIT
12
satisfy the clearance requirement of brazing(the clearance requirement is 0.1~0.2mm normally).
4.2.3 Selection of Piping
(1) Ensure the inside of the pipes is clean and no foreign materials.
(2) Pipe specifications:
R410A System
Pipe Φ
（
mm/inch
）
Thickness(mm)
Temper grade of piping material
Φ6.35
（
1/4
）
≥0.8
O
Φ9.52
（
3/8
）
≥0.8
O
Φ12.70
（
1/2
）
≥0.8
0
Φ15.9
（
5/8
）
≥1.0
0
Φ19.05
（
3/4
）
≥1.0
0
Φ22.2
（
7/8
）
≥1.2
1/2H
Φ25.40
（
1/1
）
≥1.2
1/2H
Φ28.6
（
9/8
）
≥1.2
1/2H
Φ31.8
（
5/4
）
≥1.3
1/2H
Φ34.90
（
11/8
）
≥1.3
1/2H
Φ38.10
（
12/8
）
≥1.5
1/2H
Φ41.30
（
13/8
）
≥1.5
1/2H
Φ44.5
（
7/4
）
≥1.5
1/2H
Φ51.4
（
7/4
）
≥1.5
1/2H
Φ54.1
（
17/8
）
≥1.5
1/2H
4.2.4 Cautions for Brazing
(1) Make sure there is nitrogen protection during welding.
Brazing without carrying out nitrogen replacement or releasing nitrogen into the piping will
create large quantities of oxidized film on the inside of the pipes, adversely affecting valves and
compressors in the refrigerating system and preventing normal operation.
(2) When brazing while inserting nitrogen into the piping, nitrogen must be set to 0.02 MPa
with a pressure-reducing valve (=just enough so that it can be felt on the skin).
Fig.4.2.4
a) Refrigerant piping
b) Part to be brazed
c) Taping
d) Hands valve
e) Pressure-reducing valve
f)
Nitrogen
(3) For details, see manual of the outdoor unit.
Notes:
