Hey everyone,

I am new to this site and was wondering if anybody could help me out. I took a sample of a new lube and it contained 241/ppm Phos. I contacted the manufacturer and they said there is no additive package with this oil. So I took another sample 154/ppm Phos and a third sample 2/ppm phos. All three of these samples were taken from different containers. The nine compressors have a Phos level on between 2-20/ppm. Why would this be? And where is the Phos coming from?

Hello ddavis and welcome to this forum.

I trust you do mean Phosphorus when you write Phos..

I have the same experience regarding a special brand of compressor oil. The funny thing is we recieved a product sample from the manufactorer, tested it and found P and som Ca. We sent an sample (from the same can) to another lab and they also found P and Ca (we use RDE, they used ICP). A third sample was sent back to the manufactorers lab: They found no P or Ca with ICP.

We sent a sample to our RDE instrument manufactorer who tripple tested (three different instruments) the oil and found P and Ca.

Conclusion (from our side) is that the oil contained 40-50 ppm P and some Ca, but not part of product specification (likely from contamination in the production line or something).

If your compressors are ref. comp I think you should investegate. Some additives may react with the cooling medium and create problems.

Mr, Hughes, I'm not so sure I agree with the statement that additives react with the 'cooling medium'. Some formulations of antiwear additives contain acidic materials that will react with the metal components of the systems (what they were put into the lubricant to do), or could be adsorbed by the desiccant system (an undesireable side effect). The end result is the TAN value will drop intially as the system first runs and the acidic components of the additive package are removed.

Copeland compressors charged with POE used an additive that sometimes can cause deposits to form in systems, but they have since removed the material. This was not a reaction with the refrigerant, but was a decomposition of the additive caused by excessive temperature at an iron surface.

Do you have some other issues with refrigeration lubricants where additives have reacted to cause problems?

Mr. Refrig Guy.

I do not personally have any experience with additives reacting with the refrigerant (as far as I know). This was just a simplified statement based on feedback from some of our customers. That is also why I did not go in details.

I think that the discrepancies come from the instruments used for testing. Instruments have difference in sensitivity, and also calibration practices. For example, some instruments can see down to 1 ppm, and others cannot see anything below let say 20 ppm. If a lab reports to you “zero” phosphorus throw this report in a garbage can. They should report it as “less than 1” or 5 or 50 or whatever. At least you would know more than when they say “zero”.

Sampling practices and cross-contamination are often reasons for discrepancies in results. My suggestion is; run an acid digest trace metals by ICP. That way, it would be eliminated differences between viscosity the calibration solution and the sample, and possible minimize/eliminate miss-readings.

John is right in his comments.. it is often poor lab proceedures and old instrumentation..

ICP does have a significant human error component and if the preparation is poor the results are poor..

best bet is to get an XRF, we have a panalytical xrf and you take the sample prep out of the issue and we get good results every time.

also dependant to where you are located in the world to the regulations you must follow,

in certain countries they do not need to test for the elemental concentration, as long as they know what they have added..so the reporting is useless especially if cross contamintaion occurs

cheers