Got a Rotating Bomb Oxidation result of 70 minutes for a mineral turbine oil ISO 32 grade.
Does this mean anything without have the value for new oil?

Den

It's a safe assumption that 70 minutes is less than 25% of your new turbine oil value. (According to ASTM D 4378, you should change your turbine oil when the RPVOT is 25% of new.) What kind of turbine oil is it? How old is it? There is a good chance that someone on this forum can give you an approximate RPVOT value for new.

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Originally posted by Greg Livingstone:
It's a safe assumption that 70 minutes is less than 25% of your new turbine oil value. (According to ASTM D 4378, you should change your turbine oil when the RPVOT is 25% of new.) What kind of turbine oil is it? How old is it? There is a good chance that someone on this forum can give you an approximate RPVOT value for new.

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The RBOT test value vary based on base oil quality . If base oils are hydrocracked, it will be in the range 600 - 800 mts. If base oils are solvent refined , RBOT value will be in the range 300 - 400 mts . With regard to rejection limit, user should look into all parameters such as viscosity, TAN , water content, color etc in addition to RBOT. 50% drop RBOT value is a warning level kumartr2@yahoo.com[/IMG]

See my post concerning Mg Set oil on page 2 for some good info. Anything less than 100 with an increasing AN number means trouble. Our T-G oil baseline is about 450 and trends about 180-200 minutes.

Dear Dennis

If you have 70 minutes of RPVOT (RBOT), that means that you have a 17% of a new oil (Group I Mineral Oils have like 400 minutes of RBOT).

This value, like the other people in the Forum comments, is lower than the 25% of the new value, and according to ASTM D-4378, this in an inicative that the oxidation inhibithor additive is not present in the sufficient quantity.

In the other hand, you have to check the TAN (Total Acid Number), value. If this is higher than permited in ASTM D-4378, you must change the oil.

If you have more doubts, don´t hesitate to contact me.

Check with your oil manufacturer they will be able to tell you when the RBOT limit has been reached and you will then know if you should change it or not.