Oil Foaming Problem - HELP!

[Morries]

Hi All,

Need some advise, I recently took over maintenance of a butchery store
Have lost a compressor on the freezer room (windings failed because of failed contactor and wrong overload installed) The original compressor was marked R408a Gas but no mention of oil type

We installed a rebuild compressor which was supplied with mineral oil, we have done all the necessary flushing of the system and installed new liquid line drier, suction burnout core drier and evacuated system.

After starting the system I noticed the oil foaming in the compressor oil sight glass, I have done several oil changes with no visible improvement, the oil also takes a bit too long to return to the compressor?

Do I have mixed oils? Should I change to ester oil?

Morries

[mikeref]

Are you using R408a with this compressor?
R408a is, or was a drop in for R502. It can be used with mineral/ alkylbenzene or POE.
Had nothing but trouble with that gas when ambient temps reached the 30's C and the oil turned dark within a few weeks.
Your room could do better with an oil seperator. As for the foaming oil, consider raising the oil level to 3/4 glass level, however, with poor oil return, fit an oil seperator first.

[chemi-cool]

Foam in oil is from returning refrigerant to the sump.
Your TXV is too open and part of the refrigerant boils in the oil and makes it foamy.

[HVACRSA]

Every compressor I have been checking lately the oil is foaming ;)