Brazing - Mitsubishi City Multi PURY-P400 Service Handbook

[3] Brazing

No changes have been noted from the conventional method, but special care is required to keep contaminants (i.e. oxide
scale, water, dirt) from entering the refrigerant circuit.
Example : Inside a brazed section
When non-oxide brazing was not used
Items to be strictly observed :
1. Do not conduct refrigerant piping work outdoors on a rainy day.
2. Apply non-oxide brazing.
3. Use a brazing material (BCuP-3) which requires no flux when brazing the sections between copper pipes or between
a copper pipe and copper coupling.
4. If installed refrigerant pipes are not immediately connected to the equipment, then braze and seal both ends of them.
Reasons :
1. The new refrigerant oil is ten times more hygroscopic than the conventional oil. The probability of a machine failure
due to water infiltration is higher than with conventional refrigerant oil.
2. A flux generally contains chlorine. A residual flux in the refrigerant circuit may generate sludge.
Note :
• Commercially available antioxidants may have adverse effects on the equipment due to its residue, etc. When
applying non-oxide brazing, use oxygen free nitrogen (OFN).
When non-oxide brazing was used
–6–