MovinCool Office Pro W20 Service Manual - Manual (Page 64)

Repair Section
64
11. REFRIGERANT AND WATER SYSTEM REPAIR
11.1 Repair of Refrigerant and Water System
• In case there is a leak, obstruction, or problem in the refrigerant and water system of this unit,
replace or repair the part in question. After replacing any component, all connections must be
brazed except the flare connections of the water regulating valve.
(1) Proper brazing techniques
• It is desirable to use a slightly reduced flame. Oxyacetylene is commonly used since it is easy
to judge and adjust the condition of the flame. Unlike gas welding, a secondary flame is used for
brazing. It is necessary to preheat the base metal properly depending on the shape, size or
thermal conductivity of the brazed fitting.
• The most important point in flame brazing is to bring the whole brazed fitting to a proper brazing
temperature. Care should be taken to not cause overflow of brazing filler metal, oxidization of
brazing filler metal, or deterioration due to the overheating of flux.
(2) Brazed fittings and fitting clearance
• In general, the strength of brazing filler metal is
lower than that of the base metal. So, the
shape and clearance of the brazed fitting are
quite important. As for the shape of the brazed
fitting, it is necessary to maximize its adhesive
area. The clearance of the brazed fitting must
be minimized to facilitate brazing filler metal to
flow into it by capillary action.
(3) Cleaning brazing filler metal and pipe
• When the refrigeration system has been opened up, exposure to heat may have caused brazing
filler metal to stick to the inside and outside of the pipe. Brazing filler metal may also be
compounded with oxygen in the air to form oxide film. Fats and oils may stick to the pipe from
handling. All these factors can reduce effectiveness of brazing. It is necessary to eliminate
excess brazing filler metal using sand paper and by cleaning thoroughly with a solvent such as
trichlene.
CAUTION
Do not use chlorine cleaner.
I002225
Clearance
Clearance From The Pipe Fitting and Tubing.
0.001~0.003 in
(0.025~0.075 mm)
a
a