Fujitsu AUYG18LVLB, Design & Technical Manual

Page: 204 / 343

CAUTION
• Brazing:
– While brazing the pipes, be sure to blow dry nitrogen gas through them.
– If nitrogen gas is not blown through the pipes while they are being brazed, an oxidized layer
may form on the inside of the pipes. If this occurs, the cooling efficiency may decrease and
the air conditioner unit (compressor, valves, etc.) cause malfunction.
0.02 MPa
Pressure hose
Belows valve
Nitrogen gas
Rubber stopper
– When brazing the pipes, do not use flux. If the flux is chlorine-based, the pipes will corrode
and when the flux contains fluorine, the refrigerant oil will deteriorate, etc. Using the flux has
an adverse affect on the refrigerant piping system.
– For brazing materials, use phosphor copper solder that does not require flux.
• Piping treatment:
– The pipes vibrate, expand, and contract during operation, so if loads are concentrated in one
area, it could cause cracks in the pipes. Provide the pipe supports every 2 to 3 m.
– Make sure to insulate the refrigeration pipes separately with ample thickness of heat-resistant
polyethylene form etc. For the connecting portion, apply the enough insulation to avoid any
gap.
¢
Example
• Brazing
While brazing the pipes, be sure to blow dry nitrogen gas through the pipes. If not used, it will
be caused to damage for compressor and clog the strainer and electronic expansion valve.
Example: Inside state of brazing pipe section
Nitrogen gas used
Nitrogen gas used but not sufficient
(Oxigen gas still inside the pipe)
Nitrogen gas does not used
- 196 -
3-1. Caution of piping 3. Pipe installation
SYSTEM DESIGN SYSTEM DESIGN