R407C and alkylbenzene oils.

[nevgee]

I came across a Bristol two speed compressor running on R407c in a dehum system. The compressor is a refit into a system that was originally running on R22. The compressor is R22 designated as shown by the model number H2G**** and has Zerol alkylbenzene oil. I believe the system has been regassed with R407C ( 24kg) and has been running without issues for over 2 years.

My understanding is that AB oil is not ideally compatible with R407C, however I have a read a Shrieve chemicals report that suggests using AB oils with R407C is possible in some cases.

" HFC applications
Recent studies have shown that oils derived from ZEROL™ alkylbenzenes can be used with HFC refrigerants such as R134a, R407C, and R410A in specific applications. These applications include household refrigerators, window air conditioning units, and small split systems. Major advantages of using ZEROL™ alkylbenzene oil instead of polyolester oil in these HFC systems include significant cost savings in both oil and in handling procedures, and also superior lubrication in certain systems."

http://www.shrieve.us/scp/htmls/refrigeration.html

I would be interested in hearing if any of you guys have experience of this configuration in larger systems.

[monkey spanners]

I wonder if they changed the oil in the comp to ester?

[nevgee]

They placed a label to indicate the gas was R407C but left the Zerol oil label in place. I would have thought they would have removed the label. The service records show R407c change but no mention to oil .
There has always been some mystery with oil compatibility over the period of change from HCFC's to HFC's. I guess as time passes and more field studies are reported we are likely to see some of the cautionary advise was perhaps over egged.
There was the case with R22 and POe. Compressor manufacturers wouldn't warranty a compressor if R22 was used with POe oil. but we now know it's ok to use this combination.