Acid Formation; Inadequate Compressor Cooling; High Discharge Temperatures; Motor Burnout Due To Undersized Contactors - Emerson Copeland Discus Series Application Manuallines

7.5

Acid formation

Acid forms in the presence of moisture, oxygen, metal salts and metal oxides, and/or high
discharge temperatures. The chemical reactions are accelerated at higher temperatures. Oil and
acid react with each other. Acid formation leads to damage of the moving parts and in extreme
cases to motor burn-out. Several different test methods can be used to test for acid formation. If
acid is present, a complete oil change (including the oil in the oil separator) will help. A suction
filter that removes acid should also be fitted. Check filter-drier condition.
7.6

Inadequate compressor cooling

Cooling fans must be fitted on certain compressor models. If the fan does not provide sufficient
cooling high discharge temperatures can result. The only solution is to fit an appropriate cooling
fan.
7.7

High discharge temperatures

The limit is 120°C measured on the discharge line a few centimetres from the service valve.
Symptoms of high discharge temperatures are cutting-out on the high pressure switch (dirty
condenser), oil carbonisation, black oil and acid formation. Inadequate lubrication is the result.
The condenser should be cleaned regularly. The evaporating temperature should not be allowed
to fall below the application limit of the compressor.
7.8

Motor burnout due to undersized contactors

If contactors are undersized the contacts can weld. Complete motor burnout on all three phases
despite the presence of a functioning protection system can be the result. If the application point
of a compressor is changed the contactor sizing should be rechecked.
7.9

Motor burnout due to by-passed or disconnected protectors

If large sections of the windings are burned out, it must be assumed that the protector was either
not connected or by-passed.
8 Dismantling & disposal
Removing oil and refrigerant:
Do not disperse in the environment.
Use the correct equipment and method of removal.
Dispose of oil and refrigerant properly.
Dispose of compressor properly.
28 D6.3.4/0715-0716/E