refrigerant was examined for the presence of decomposition
products. Table 3 summarizes typical data
for both HFC-134a and CFC-12. Visual ratings are
listed for the neat lubricant, the lubricant/refrigerant
solution and the three metals that were present in the
lubricant/refrigerant solutions. Viscosity was determined
on the unused lubricant, the tested neat lubricant,
and the lubricant tested in the presence of
refrigerant. A percent change was calculated for the
two tested lubricants. The decomposition products
listed are HFC-143a (the predominant decomposition
product for HFC-134a) and fluoride ion. Both
species are typically measured in the low parts per
million (ppm) range.
As the CFC-12/mineral oil combinations have been
proven in actual service, these tests indicate that
HFC-134a/PAG and HFC-134a/POE solutions have
acceptable chemical stability. In several other tests,
results have confirmed that the HFC-134a molecule
is as chemically stable as CFC-12.