Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

3
Refrigerant Management
CHAPITRE 3
PAGE 19
Test refrigerant for contamination
Refrigerants can be tested for water/oil contamination and acidity
with a test kit. With the change to alternative refrigerants, in many
cases, has come need for new lubricants. Where retrofit procedures
call for the removal of mineral-based oil and replacement with ester
lubricants, it is necessary to reduce the mineral lubricant to a minimal
level. These test kits provide simple methods of determining the level
of residual mineral oil in an ester lubricant mixture.
Test oil contamination
It is possible to test the oil in some systems for acidity. Acid in the
oil indicates that burnout or partial burnout has taken place, and/or
that there is moisture in the system, which can cause a burnout.
To carry out an oil test it is necessary to remove a sample of oil from
the compressor without undue release of refrigerant. The procedure
for this will vary depending
TEST KIT
on the arrangement of shutoff
valves and access to the oil
available on the unit. For many
hermetic compressors there
will be neither shut off valves
nor access. This image shows
an example of a refrigerant
testing kit.
Refrigerant testing kit
The refrigeration oil acid test kit is one-bottle (one step) test, and
is the fastest way of determining if compressor oil is safe or acidic.
If the test result in the mixture remaining purple, the oil is safe,
whereas if it turns yellow, it is acidic. The ultra-sensitive colour
change guarantees an accurate test.
Checking of refrigerant cylinders
Decanting refrigerants into service cylinders is a hazardous practice.
It should always be carried out using the method prescribed by the
refrigerant manufacturer.
Special care should be taken:
• Not to overfill the cylinder
• Not to mix grades of refrigerant or put one grade in a cylinder
labelled for another CHAPITRE 3
• To use only clean cylinders, PAGE free 20 from contamination by oil, acid,
moisture etc.
Cylinder with separate liquid and gas valves
• To visually check each cylinder before use and make sure all
cylinders are regularly pressure tested
• Recovery cylinders should have a specific indication depending
on the country in order not to be confused with virgin refrigerant
container
• Cylinders should have
separate liquid and gas
valves and be fitted with a
pressure relief device, as
shown in the diagram:
Cylinder with separate liquid and
gas valves
Vapor
Liquid
77
Yellow
Cutaway view
Grey