MAYEKAWA 4M - 4 Operation of the Compressor; Refrigeration Oil Properties and Selection

Reciprocating Compressor M Series
4-1
4 Operation of the Compressor
4.1 Refrigeration Oil
The refrigeration oil is used for lubricating the moving parts of the compressor, preventing abnormal wear, and
cooling each section.
The following oil properties are required:
z There should be an appropriate viscosity under the operating temperature and pressure conditions.
z The oil should flow even under the low temperature conditions (within the range of operating
temperature for the refrigerant system).
z The oil should be chemically±stabilized so that it does not corrode or breakdown the components (such
as metals or rubbers).
z Wax should not be separated from the oil even under low temperature.
z Sludge and carbon should not be generated easily even under high temperature.
z Water should not be contained in the oil.
4.1.1 Precautions for Selecting Oil
z Brands to be used differ depending on the types of refrigerant. For details, contact your sales office or
Mayekawa representative.
z Do not
use the Polyolester (POE) oil.
z Do not
use Hydro treated mineral oils
z Naphthenic based mineral oil of ISO±VG 46-68 is recommended.
z The viscosity of the oil selected must stay 20²70 cSt under usage condition.
z The circulation of the oil for the overall equipment must be taken into consideration. After the
refrigerant oil lubricates/cools each section of the compressor, it returns to the oil tank of the crankcase.
However, some of the oil is discharged together with the refrigerant. Most of the oil discharged from the
compressor is captured by the oil separator while some of it flows to the condenser or evaporator. As
described above, there should be sufficient ways for the oil to be returned to the correct locations.
 To change the brand oil:
z Changing the existing oil with other brand oil may cause an unexpected problem due to mixing of new
and old oils. Ensure sufficient oil flushing is completed before running compressor with oil approved by
Mayekawa.
z If the manufacturers are different, contact both of them to confirm whether changing the oil is going to
cause problems. The same confirmation is required for changing the brand even if it is of the same
manufacturer.
z There is no problem in changing the viscosity level within the same brand. As long as the change in
viscosity matches the operation conditions.
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