We now get this analysis question at Nedlab in 2024 with some regularity. The question behind this question is: can the compressor do its job properly and how can we get ahead of wear / internal damage?
Of course we can, and we do so with the following analysis steps:
- Visual assessment;
- Determination of the acid number of compressor oil;
- Determination of anions after extraction;
- Wear analysis with XRF and SEM-EDX.
The analysis results in the following:
Visual: can particles be observed in the oil sample? If yes: are the observed particles metallic?
Has uncontrolled oxidation occurred? The oil is normally alkaline due to the added additives. If the additives oxidize to some extent, the acid number will change. The acid number is an indicator of the degree of depletion and thus says something about the need to replace the oil. It is also an indicator of whether wear may have occurred (uncontrolled oxidation);
If the particles are metallic what is the composition and that will give an idea if there has been wear on, for example, the bushing which is around the bearings.