Interfacial tension measurements on electrical insulating oils provide a sensitive means of detecting small amounts of soluble polar contaminants and products of oxidation. A high value for new mineral insulating oil indicates the absence of most undesirable polar contaminants. The test is frequently applied to service-aged oils as an indication of the degree of deterioration.

FIG. 1 Interfacial Tensiometer

FIG. 2 Top View of Interfacial Tensiometer

1.1 This test method covers the measurement of the interfacial tension between mineral oil and water, under non-equilibrium conditions.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.