We operate a Mitsubishi single shaft steam turbine and combustion turbine with a combined control oil system. The fluid is maintained in relatively good condition with particulate and fullers earth filtration. The system was commissioned and filled with Shell Irus DR46. We are currently finding it more difficult to procure this product and have been informed that it may be out of production.

Can another manufacturer’s phosphate ester fluid be used for topping off the system?
Should I be concerned of incompatibility causing issues with the fluid?
Do other users have experience with mixing and using different brands?
Are users aware of any compatibility charts?

All assistance will be appreciated.

Best regards,
Scott

The DR 46 is a phosphate ester.

So there is hope.

We use a couple of different versions of Supresta Fyrquel that are phosphate ester based.

I would call them.

Regardless, get someone like Herguth to do full comapatibility testing.

Webster,

As long you stay with the same base oil (phosphate ester?) you will not see any problems because base oils of the same kind are compatible. What causes possible incompatibility are different additive packages used for blending final product.

Take the advice from RobertC and send sample of your in-service oil and a sample of new oil to Herguth Labs for compatibility testing. I'd suggest calling them first to discuss your case; whether ASTM D 7155 would be the most appropriate in your case (maybe Tier 1 or Tier 1 and Tier 2 analysis) or some other method. Make a habit of testing for compatibility every time you plan to buy new oil for use either as a make up oil or the replacement oil. Such approach is the best assurance that you will not have any problems which may be caused by possible incompatibility.

Thank you for your recommendations. I will post additional details of the analysis.