Mitsubishi Electric CITY MULTI PUHY-400YMF-C, Руководство по обслуживанию, Страница: 7 / 209

-4-
[3] Brazing
No changes from the conventional method, but special care is required so that foreign matter (ie. oxide scale, water, dirt,
etc.) does not enter the refrigerant circuit.
Example : Inner state of brazed section
When non-oxide brazing was not used When non-oxide brazing was 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 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 10 times more hygroscopic than the conventional oil. The probability of a machine failure if
water infiltrates 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).