McQuay SB250B Installation Manual page 15

Piping Works & Brazing Technique
• Do not use contaminated or damaged copper tubing. If any
pipings, evaporator or condenser had been exposed or had
been opened for 15 seconds or more, then vacuum and purge
with field supplied refrigerant. Generally, do not remove
plastic, rubber plugs and brass nuts from the valves, fittings,
tubings and coils until it is ready to connect suction or liquid
line into valves or fittings.
• If any brazing work is required, ensure that the nitrogen gas
is passed through coil and joints while the brazing work is
being done. This will eliminate soot formation on the inside
walls of the copper tubings.
• Cut the pipe stage by stage, advancing the blade of the pipe
cutter slowly. Extra force and deep cut will cause more
distortion on the pipe and thus extra burr. See figure.
• Remove burrs from cut edges of the pipes with remover as
shown in the figure. Hold the end of the pipe downwards to
prevent metal chips from entering the pipe.
Piping Connection To The Units
• Align the center of the piping and tighten the flare nut
sufficiently with fingers.
• Finally, tighten the flare nut with the torque wrench
until the wrench clicks.
• When tightening the flare nut with the torque wrench,
ensure that the tightening direction follows the arrow
indicated on the wrench.
Pipe Size (mm/in)
6.35 (1/4")
9.53 (3/8")
12.7 (1/2")
15.88 (5/8")
19.05 (3/4")
Torque (Nm)
18
42
55
65
78
1-5
Cutting Copper Tube
1/4t
Copper Tube
Remove Burr
Flare Joint
Flared Tube
Indoor Piping
Torque Wrench
Spanar
Flare Nut