Hi all!

I would like to check the aging of refrigeration compressors oil. I'm searching for simple and economical ways of determining the oil status. Apart from viscosity, I thought to measure TBN or TAN.
For an internal combustion engine, it looks like TAN is a good indicator of oil age, but in my case, the compressors are working with ammonia (basic) and there is no combustion.
Do you think a measure of TAN would still be useful or should I check for TBN? Or neither TAN nor TBN are useful?

Any suggestions welcome, thank you all in advance

Regards

Marko Germani

I think TAN is very important for NH3 systems. By including this you will get an indicator of chemical reactions in the oil like oxydation. Remember to test new, unused oil to get the normal value.

(I would claim that TBN is a good indicator for oil age in combustion engines, not TAN)

Thank you. I've just finished reading the text "Converting to condition-based oil changes" found in this site and I recognized I was wrong. You are right, TBN is the proper indicator for oil age in combustion engine.

Ok then, for my NH3 plants I'll go for TAN tests, along with viscosity measures.

Thank you again

Marko

Make sure the lab degasses the oil samples before viscosity is measured. Or you will get strange results.

You should also get water content in ppm. NH3 systems should contain very little moisture.