Acid Number (TAN) in Turbine Oils – Everything You Need to Know 1. What Acid Number (TAN) Really Represents The Total Acid Number (TAN) is the amount of potassium hydroxide (KOH) required to neutralize acidic species in oil, expressed in mg KOH/g. From a turbomachinery perspective, TAN is not just acidity—it is a proxy for oxidation progression, additive depletion, and … Continue reading Acid Number (TAN) in Turbine Oils – Everything You Need to Know