McQuay MWSC 010 Series Manual page 39

Piping Connection
1) Do not use contaminated or damaged copper tubing. If any piping, evaporator or condenser had been exposed
or had been opened for 15 seconds or more, then vacuum and purge with fi eld supplied refrigerant. Generally, do
not remove plastic, rubber plugs and brass nuts from the valves, fi ttings tubing and coils until it is ready to connect
suction or liquid line into valves or fi ttings.
2) If any brazing work is required, ensure that nitrogen gas is passed through coil and joints while the brazing work
is being done. This will eliminate soot formation on the inside wall of copper tubing.
3) Cut the pipe stages by stages, advancing the blade of pipe cutter slowly. Extra force and a deep cut will cause
more distortion of pipe and therefore extra burr.
4) Remove burrs from cut edges of pipes with a remover. This will avoid unevenness on the fl are face which will
cause gas leak.
5) Align the center of the piping and suffi ciently tighten the fl are nut with fi ngers. Finally, tighten the fl are nut with
torque wrench until the wrench clicks.
6) Be sure to execute heat insulation (polyurethane form with thickness more than 15 mm).
7) Except the outdoor unit which is pre-charged with refrigerant R22, the indoor unit and the refrigerant connection
pipes must be purged because the air that contain moisture remaining in the refrigerant cycle may cause
malfunction to the compressor.
Vacuuming and charging
The precharged outdoor unit does not need any vacuuming or charging, However once it is connected, the connecting
pipe line and the indoor unit need to be vacuumed before releasing the R22 from the outdoor unit.
1) Open the service port core cap.
2) Connect pressure gauge to the service port.
3) Connect the line to vacuum pump, open the charging manifold valve and turn the pump on, vacuum to -0.1MPa(-
76cmHg) or lower (Evacuation time varies by the pump but averagely in 1 hour).
4) After evacuation, unscrew the spindle for the gas to run to indoor unit.
Outdoor unit
Check valve
Flexible pipe
Indoor unit
Refrigerant pipe
Low pressure guage
Charge set
Page 38
High pressure guage
Flexible pipe
Charge cylinde
R22
Scare pan