I want to know what make up Compressor Oil (specifically R134A)? Is it some synthetic base?

The refrigeration oils for R134a are usually made of synthetic oils like POE (polyol ester) or AB (alkyl benzene)

Yes indeed, it's based on POE's and to complete the answer:

- it's not miscable with mineral oil

- it's based on CFK replacements HFCK's and HFK's

Hope this helps you out.

Hazel, R-134a automotive A/C systems almost always use PAG lubes from the factory, sometimes POEs are used for retrofits from R-12 to R-134a. The PAGs are either single end capped or double end capped depending on the automotive manufacturers need for chemical stability.

R-134a stationary A/C and refrigeration systems normally use POE lubes. Some Japanese equipment manufacturers are starting to investigate PVE lubes, especially with rotary compressors.

AB, PAO and mineral oils are very difficult to use with R-134a due to the poor mutual solubilty between the refrigerant and lube. There are limited situations where they can be used when the equipment design and application conditions make oil return issues less of a problem.

Refrig Guy

Just need a clarification on a particular product by name Suniso 3GS from Summito corporation of Japan used in refrigeration compressors with R 134a refrigerant . Is it manufactured with PAO or POE or Alkyl Benzene?

What will be the best type of lubricant for enclosed type reciprocating compressors?

Franky, Suniso 3GS is a naphthenic mineral oil, the standard lubricant used with CFC refrigerants. This oil will be difficult to move around the system with R-134a due to the poor solubility. Your particular application may work with 3GS, but you will need to test the oil return characteristics very carefully to prevent any issues with poor oil circulation. There are very few companies who have used mineral oils with HFCs, unless an oil return enhancer was added to the refrigerant (like propane or pentane). Adding a substantial amount of POE lubricant will also help circulate the mineral oil.

The most common lubricant used with hermetic recips using R-134a are POEs. There are two main types available, ones based on branched acids for better hydrolytic stability, and ones based on linear acids for better thermal stability and lubricity. The Japanese prefer the branched acid POEs while the Europeans and Americans prefer the linear POEs. The linear POEs are able to go to very low viscosities (<7 cSt at 40C) for good energy efficiency and still maintain lubricity.

Both products work in a well manufactured system.