MAINTENANCE & REPAIR 31
ENTERING THE SYSTEM
Entering the system should only be done as a last
resort. Extreme care must be used no matter what the
reason is for entering the system. Of course there are
times it cannot be avoided, such as component or
compressor replacement, or a leak within the system.
The system must also be entered any time you need
to obtain the operating pressures. Again, use extreme
caution to avoid any possible contamination.
Cabinets that use semi-hermetic compressors allow
easy access through the valve ports.
Cabinets using hermetic compressors do not have
valve ports, this product has process stubs for both
suction and discharge sides of the system.
Line taps should only be used to obtain pressure
readings, and not for reprocessing a system. The
opening of a line tap is too restrictive for pressure of
vacuum procedures.
Install hand valves at the process stub ends. Hand
valves will be less restrictive to flow because of a
larger opening. They will also be easier to use during
repair procedures.
EVACUATION
Once the system has been cleaned and components
have been replaced, you are ready to initiate the final
servicing procedures necessary to achieve proper
cabinet operation.
Pull an evacuation to approximately 50 microns.You
can be sure that any contaminants that can affect the
system’s operation are now removed.
Use this time to check any joints for potential leaks.
CHARGING
You should use a charging cylinder to measure in the
the correct amount of refrigerant. The charging
methods are:
1) Add the refrigerant to the system until you reach a
predetermined balanced pressure. This will give you
an approximate static charge.
2) Weigh in the refrigerant using a scale calibrated in
ounces.
The cabinet’s operation is now ready to be tested. A
final check of the refrigeration lines should be made
before running the cabinet.
Be sure the refrigeration lines are not kinked or
rubbing against each other.
Also check that the door seals properly. An air leak will
affect proper operation, and the cabinet’s ability to
reach its coldest temperature.
Run the cabinet a both 100% run and also at a
cycling temperature for at least one day. If the
temperature and pressures are correct, the system
can be considered repaired.
Hermetic systems should now have their process
stubs pinched off, hand valves removed and the ends
brazed shut.
Dipping Cabinet 1298.02 2/3/03 1:14 PM Page 33
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