retrofitting with non-cfc substitutes

RETROFITTING WITH NON-CFC SUBSTITUTES
No problem has been experienced with the use of HFC-134a in our compressors as a retrofit
refrigerant for CFC-12 ( with a limited amount of vehicle testing complete).
Mineral oils need to be changed to a lubricant compatible with HFC-134a. Work being done
by ICI and Sanden in using an ICI ester oil as a drop-in lubricant with HFC-134a, offers
significant advantages to the service industry. At present, ester oil seem to be a better lubricant
than PAG oil, because they mix well with HFC-134a, and appear to be miscible with existing
mineral oils. Japanese manufacturers do not advise using blends so we will go direct to HFC-
134a for retrofitting.
Roke, Lindsey, 1992: Report from the Technical Options Committee on Refrigeration.
Paper presented at the Asia-Pacific conference on the phasing out of ozone depleting
substances, 5-7 October 1992, Singapore
Australia is notable for automotive air conditioning conversions where they are finding that it
is generally proving little more difficult to apply HFC-134a than to apply ternary blends. In both
cases barrier hoses are highly desirable if not essential to cut emission losses. Note though, that
many cars being built today are already fitted with such barrier hoses even though they are still
using CFC-12. This certainly appears to be a good move by the automobile manufacturers.
HFC-134a has a slightly lower critical temperature than CFC-12, and each conversion has to
be evaluated on its own merit. In other words it is a system-specific conversion.
Problems
Capillary blocking: It is necessary to make sure that contaminants are not on the system, as they
are liable to deposit towards the end of the capillary and reduce flow by some 15-20%. The
technique for handling this problem is to make sure that there is no contamination in the
system.It is essential to keep moisture levels to the minimum.
SUVA MP52 retrofit for CFC-12
Bateman, D., 1992: New refrigerants for MAC. Paper presented at the Asia-Singapore
conference on the phasing out of ozone depleting substances, 5-7 October 1992, Singapore.
This is a 3 component blend, containing HCFC-22, HFC-152a, HCFC-124.
Benefits
Good environmental properties. DuPont has selected a mixture of mineral oil with alkylbenzene
lubricant, eliminating the need to flush the system, as laboratory tests have confirmed that
alkylbenzene and the MP52 are compatible with residual CFC-12 and mineral oil. MP52 is not
flammable. Provides cooling properties similar to CFC-12.
Conclusion:
DuPont believes there are two viable options: HFC-134a and SUVA MP52. Neither is a drop-in
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