I have a oil sample from a bearing in a generator from a power plant. The analysis results are mostly acceptable (No abnormal wear, no contaminants, correct TAN and visc). No microbacterial traces (SRB/GAB). Water content approx 60 ppm.

Abnormal: approx 50% reduction in Phosphorus and Magnesium.

The problem is the smell. The oil smells like septic waste. Really strong.

Any comments on this?

This message has been edited. Last edited by: mr. Hughes,

The rotten egg smell may be Hydrogen Sulfide. H2S is a colorless gas which can be detected by smell at levels as low as 2 parts per billion. To put that in perspective 1mL of gas distributed evenly through out a 100 seat movie theater is about 20 ppb. H2S can form due to anaerobic decay added by bacteria. You have stated that the test does not show micr bio growth. However you need to consider that this growth may be occuring in an area of the system such as the inner top of the oil tank that is not regularly being washed by the oil. Please note that H2S gas overtime will deaden the sense of smell and in confined spaces can be deadly.

Thanks for your feedback.

We have requested sample of any potential deposit in reservoirs for further analysis.

Would you recommend replacing (If H2S) the oil after doing a flushing/cleaning process?

My experience with SRB's and the smell:

The SRB's were in the oil/water interface in the lube oil bulk-storage tank. Look for water in places you don't expect to find it, or that take for granted are not there. It is very difficult to test for bacterial growth in the oil (which is probaqbly why you did not find any), much easier to find them in the water, but if you look for the oil/water interface, you will find them there, if they exist.

Also, you say the levels additives changed. Are you sure someone has not added EP gear oil(?) and you are smelling the sulphur additive?

Andy

Thanks guys, this is interesting.

Could potential microbacterial growth effect or cause the reduction in both Phosphorus and Magnesium?
The oil was new in Oct 2004 and in addition it foams more than before. (200 liter system)

Dear Mr. Hughes
In reference to this issue, I agree in the tip from "Gas Turbine Guy". I have been working with Gas Compressor in Refineries, and the presence of H2S is very usual. We detect it by ASTM D-130, and Flash Point. Anyway, I don't think that in this case, H2S be the problem. You are talking about a generator from a power plant.

However, if you confirm the presence of H2S, I could comment that we use Thermojet Technology (www.lsc.com), for removing H2S from the oil.

Regards.