EN 62021-1:2003

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents and auxiliary products
   5.1 Reagents
   5.2 Titration reagent
   5.3 Titration solvent
   5.4 Potassium hydrogen phthalate, primary standard
   5.5 Potassium chloride reference electrolyte
   5.6 Aqueous buffer solutions
   5.7 Cleaning solution
6 Apparatus
   6.1 Potentiometric titration apparatus
   6.2 Glass indicating electrode
   6.3 Reference electrode
   6.4 Stirrer
   6.5 Titration vessel
   6.6 Titration stand
7 Sampling
8 Preparation and maintenance of electrode system
9 Calibration of apparatus
10 Procedure
   10.1 Standardization of alcoholic potassium hydroxide
        solution
   10.2 Blank titration
   10.3 Sample titration
11 Calculation
12 Precision
   12.1 Repeatability
   12.2 Reproducibility
13 Report
Annex ZA (normative) Normative references to international
         publications with their corresponding European
         publications
Bibliography

Describes the procedure for the determination of the acidity of unused and used electrical mineral insulating oils. The method may be used to indicate relative changes that occur in a mineral insulating oil during use under oxidizing conditions regardless of the colour or other properties of the resulting mineral oil. The acidity can be used in the quality control of unused mineral oil. As a variety of oxidation products present in used mineral oil contribute to acidity and these products vary widely in their corrosion properties, the test cannot be used to predict corrosiveness of a mineral oil under service conditions. The acidity results obtained by this test method may or may not be numerically the same as those obtained by colorimetric methods, but they are generally of the same magnitude.