R32
Split Type - Air Source Heat Pump 20220105
56
concentrations may occur in the piping, with the potential for rupturing.
2.7 Brazing
Care must be taken to prevent oxide forming on the inside of copper piping during brazing. The presence
of oxide in a refrigerant system adversely affects the operation of valves and compressors, potentially leading
to low efficiency or even compressor failure. To prevent oxidation, during brazing nitrogen should be flowed
through the refrigerant piping.
Warning
Never flow oxygen through piping as doing so aids oxidation and could easily lead to explosion and as
such is extremely dangerous.
Take appropriate safety precautions such as having a fire extinguisher to hand whilst brazing
Flowing nitrogen during brazing
Use a pressure reducing valve to flow nitrogen through copper piping at 0. 20. 3MPa during brazing.
Start the flow before brazing starts and ensure that the nitrogen continuously passes through the section
being brazed until the brazing is complete and the copper has cooled down completely.
Flowing nitrogen through piping during brazing
When joining a shorter section of piping to a longer section, flow nitrogen from the shorter side to allow
better displacement of air with nitrogen.
If the distance from the point where nitrogen enters the piping to the joint to be brazed is long, ensure that
the nitrogen is flowed for sufficient time to discharge all the air from the section to be brazed before commencing
brazing.
Flowing nitrogen from shorter side during brazing
Number
Name
1
Copper piping
2
Section being brazed
3
Nitrogen connection
4
Hand valve
5
Pressurereducing valve
6
Nitrogen
