Thermo King CRR-40 119, Руководство пользователя

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Refrigeration Maintenance and Service Operations
131
Evacuation and Cleanup of the
Refrigeration System
Contamination
Whenever contaminants have entered the system,
a thorough clean up is required to prevent damage
or loss of compressor.
It is well known by the refrigeration service
industry that the purpose of evacuation is to
remove moisture and air from the refrigeration
system before charging with new refrigerant after
a system has been opened. The importance of
thorough evacuation and system preparation
cannot be over emphasized. Even infinitesimal
quantities of air or moisture in a system can cause
severe problems.
We know that the presence of moisture, oxygen,
and heat under certain conditions can result in
many forms of damage. Corrosion, sludge, copper
plating, oil breakdown, carbon formation, and
eventual compressor failure can be caused by
these contaminants.
Things that will contaminate a system are (in
order of importance):
• AIR — with oxygen as a contaminant.
Oxygen in the air reacts with the oil. The oil
begins to break down and can eventually lead
to carbonization in the compressor and acid
buildup. The longer this breakdown process
goes on, the darker the compressor oil
becomes until finally the color is BLACK
indicating major system contamination.
• MOISTURE. Moisture in a system will cause
metal corrosion and metal plating. It can
freeze in the expansion valve and cause
intermittent operational problems. It reacts in
the oil to begin acid buildup.
• DIRT, DUST, METAL PARTICLES, OTHER
FOREIGN MATERIALS. Particles of any
kind left to float through the system will cause
severe damage to all close tolerance items. Do
not leave a system open to the infiltration of
dirt. If you must open a system for any reason,
seal off the open areas as soon as possible and
DO NOT work in a dirty environment.
• ACID. Air and moisture cause a chemical
breakdown of the oil and/or the refrigerant
itself. The acid will accelerate the
deterioration of the softer metals (i.e., copper)
and cause metal plating as the softer material
begins to cover the inside of the system. If this
condition is not stopped, it can result in the
total destruction of your equipment.
Compressor Oil Color Code
BLACK OIL — indicates carbonization caused
by air in the system.
BROWN OIL — indicates copper plating caused
by moisture in the system.
GRAY OR METALLIC OIL — indicates bearing
wear or piston scoring.
NOTE: If the compressor oil is discolored,
perform a compressor oil acid test (oil test kit
P/N 203-457). If the compressor oil shows an
acid condition, change the oil and the filter drier.
Then perform a refrigeration system cleanup.
1. Refrigerant Level:
• Air-cooled Condenser Operation: The
refrigerant charge is OK if balls FLOAT at
any time.
• Water-cooled Condenser Operation: It is
normal for the balls to float at the top of the
sight glass. To check the refrigerant
charge, operate unit on air-cooled
condenser.
Figure 43: Water-Cooled Condenser-Receiver Tank
with One Sight Glass
1
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