MovinCool CM25 Service Manual - Manual (Page 78)

Repair Section
78
8. REFRIGERATION SYSTEM REPAIR
WARNING
• Disconnect power supply from the unit before performing any service. Beware that some
residual voltages may remain in the unit immediately after the power is disconnected.
8.1 Repair of Refrigeration System
• In case there is a leak, obstruction, or trouble in the refrigeration system, replace or repair the
part in question. After replacing any component all connections must be brazed.
(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, oxidation 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.
I002225
Clearance
Clearance From The Pipe Fitting and Tubing.
0.001~0.003 in
(0.025~0.075 mm)
a
a