Hello,
We use hydraulic synthetic oil Quintolubric 888-46 for Hydraulic gun and drill in Blast furnace. Oil was put in the system in Decembar 2007. Tan value in January was 2,1mgKOH/gr, but in march decrease to 1,6mgKOH/gr. Last analysis showed 1,62mgKOH/gr. Saponification value is 162mgKOH/gr. There was no water ingress in the system, oil cleaness is good (6 according to NAS 1638). One reasone for this decrease could be mixing with mineral based oil, but is there any other reason for this decrease of TAN value? What happened to synthetic oil if some mineral oil is added to it? Thank you very much.

First before you take action check with the fluid supplier. The TAN of some products can drop as additives are used. Also, did you use the same lab each time because their can be variances. Plus, how do you know that there was no water ingress if you did not test for it? Do a Karl Fischer test. Also, did the viscosity or the SG change because they can shear down and these tests might also show mineral oil contamination as can a FTIR. Watch the results because these oils tend not to last as long as some other 'fire resistant' fluids like phosphate esters. In addition the reported saponification value is likely wrong because it was given as 162 mgKOH/gr. What is it now and what was it new? Quaker do not give it on their data sheet.

Ken

In Quaker properties for Quintolubric 888-46 typical saponification value is 180mgKOH/g according to method QTN C012 (Quaker Test Number, test descriptions developed inside Quaker. What is SG change? Does synthetic oil contain any sulphur content?