P.O.E. oil question

[bustedknuckle]

what would turn p.o.e. oil to a yellow color?

20+ yr old low temp rack system 502 with m.o. converted to hp62 (404a) p.o.e oil appox 4 yrs ago. The oil was changed one year ago with new liqiud driers rcw-48 and new
oil filter/drier of-303. Installed new oil filter today and noticed the yellow oil, never seen it before,tried acid test,(just to make sure) it passed, any ideas?

[cctrol]

Just a thought, but someone may have added dye, or it could be residual dye from before the retrofit.

[mccool]

Could be like cctrol said, worth a check with the ultraviolet light. Have seen a few R502 converts like that though, but they're all in the waste pile now, dont have an answer. Take an oil sample and have it analyzed.

[condenseddave]

FD&C Yellow #4.

Actually, I've seen this, also. I've checked it with a black light, and it doesn't glow. I have no idea what causes this.

[rayr]

Someone peeeeeed in it?????????????????

[bustedknuckle]

thanks for the repies i checked today with black light no glow. This system was filthy dirty when i started working on it now the system is clean but yellow.I stopped by the supplyhouse today also and seen sporlan flyer showing dirty
oil, before and after, looks yellow in photo too i thought
it would be more golden brown i'm going to try to get it tested i'll post results if i get any, thanks

[cctrol]

another idea is: We all know that POE is absorbent of moisture, it is possible that it has picked up contaminants as it circulated that the mineral oil wouldn't absorb.

[RobY]

Having looked at thousands of POE oil samples, along with the test results, there are a couple of possibilies.

One is the yellow color could come from the solvency of the POE picking up some varnish-like compounds from the dirty system. During retrofits to POE, the lube can go greenish as it picks up varnishes and system crud. I doubt the analysis will show anything related to the color change because there is not very much varnish compared to the POE.

Another possibility is the color may come from the antioxidant added to the POE for shelf life stability. Some POE makers use an amine based antioxidant that can darken as it comes apart. Castrol POE is one of the ones that can go from almost colorless, to dark yellow, to dark amber / orange as the antioxidant falls apart. There is no harm done when the antioxidant goes off as it was only supposed to protect the POE prior to it going into the system. Again, oil analysis will not likely show anything when this happens.

The third possibility is the POE has been overheated. POEs will darken when they are heated to above 400 degrees F. Oil analysis should show an increase in acidity if this happened. An activated carbon filter dryer should remove the color if this is the source. The filter drier will not remove the salts in the TXV or cap tube that are also formed when the POE is overheated.

[degenetron]

I would have to agree with RobY,chances are oil has been overheated,probably by high superheat,overload after defrost,etc.Compressor may also need a Head Fan.

[Andy Schoen]

POE is a great solvent. The blue/green color could be anything.

I remember a “green slime” occurring with some of the early R-502 to R-404A conversions. We had lots of fun converting from mineral oil to POE.

If you have been the only one servicing it, you have some type of contamination. I’d flush the system and start over.

[TechmanTerry]

Having looked at thousands of POE oil samples, along with the test results, there are a couple of possibilies.

One is the yellow color could come from the solvency of the POE picking up some varnish-like compounds from the dirty system. During retrofits to POE, the lube can go greenish as it picks up varnishes and system crud. I doubt the analysis will show anything related to the color change because there is not very much varnish compared to the POE.

Another possibility is the color may come from the antioxidant added to the POE for shelf life stability. Some POE makers use an amine based antioxidant that can darken as it comes apart. Castrol POE is one of the ones that can go from almost colorless, to dark yellow, to dark amber / orange as the antioxidant falls apart. There is no harm done when the antioxidant goes off as it was only supposed to protect the POE prior to it going into the system. Again, oil analysis will not likely show anything when this happens.

The third possibility is the POE has been overheated. POEs will darken when they are heated to above 400 degrees F. Oil analysis should show an increase in acidity if this happened. An activated carbon filter dryer should remove the color if this is the source. The filter drier will not remove the salts in the TXV or cap tube that are also formed when the POE is overheated.

RobY of National Refrigerants? You retired? I spoke w/ you a few time(5-6) over the years and your knowledge is impressive and very helpful. I'm associated w/ United in Ronkonkoma, LI,NY. Thanks for the help and advice.