PROCESS FOR THE DETERMINATION OF THE TOTAL ACIDITY NUMBER (TAN) OF A MINERAL INSULATING OIL
The method comprises the steps of: pouring in a container a sample of oil and a pre-established amount of a solution suitable for extracting the acid fraction of the sample; stirring the content of the container and waiting for the separation from the sample of an extract phase; dosing in the extract phase a titrant solution of KOH until an acid-base indicator present therein changes color; and calculating the TAN on the basis of the volume of dosed titrant solution according to the formula: TAN (mgKOH/goil) = (V x 56, 1 x M)/m wherein V is the volume of dosed titrant solution expressed in ml, 56,1 is the molecular weight of KOH, M is the titre of the KOH solution expressed in moles per litre and m is the mass of the sample expressed in g.