Neutralisation Number / Titration

This test is used to determine the acidic constituents by colour titration, in petroleum products that are soluble or nearly soluble in mixtures of toluene and isopropyl alcohol. It may also be used to determine basic constituents.  Oils normally are quoted with a neutralisation number or TAN/TBN range at manufacture and changes to this can indicate possible degradation while in service. An increase in the acid number of a used oil is a measure of the amount of acidic substances absorbed or created.  The value is checked against published condemning limits. The rate of change is more important than its absolute value. The results of this method do not have to agree with other measurements of Acidity or Alkalinity.