METHOD OF DIFFERENTIALLY DETERMINING OXIDATION INHIBITORS IN TRANSFORMER OILS Russian patent published in 2001 - IPC

FIELD: analytical methods. SUBSTANCE: invention relates to working properties of petroleum products and, in particular, to evaluation of contents of inhibitors in transformer oils in order to determine oil change or renewal terms. Oils are oxidized in mixture with cumene in presence of azo-bis-isobutyronitrile initiator, after which one continuously measures absorbed oxygen volume and determines induction period. Summary content of oxidation inhibitors (C, mole/kg) is found from formula: wherein Wi is initiation rate, equal to 6, 8 · 10^-8 mole/l s, P is weighed portion of oil, kg/l; τ total induction period. Content of ionol (Ci, wt.%) is determined from absorption spectrum in infrared region 3550-3800 cm^-1 and calculated from formula: Ci = 2.6116D-0.024 wherein D is optical density, and the number of freshly-formed oxidation inhibitors (Cx, wt.%) is found from expression: Cx =C/9.09*100% - Ci. EFFECT: increased accuracy of analysis. 3 dwg, 1 tbl, 4 ex