5.1 Open-beaker oxidative aging methods have been used for many years in laboratories of insulating liquid companies, electrical equipment manufacturers, and electric utility companies interested in the stability of electrical insulating liquids under oxidative conditions. They are particularly useful as a check on the continuity of production and shipment of insulating liquids. They are also useful as process and product checks for applicable type insulating liquids.

5.2 Specification limits for insulating liquids subjected to open-beaker oxidative aging by this method are established by agreement between individual producers and consumers of applicable type insulating liquids. These properties of the insulating liquid involved in specification limits for aging stability may be measured after the oxidative aging (and sometimes before aging) by appropriate test methods such as Test Methods D924, D971, D1169, and D974 or D664. Other test methods such as D445 can be used when deemed appropriate.

1.1 This test method covers two procedures for subjecting electrical insulating liquids to oxidative aging:

1.1.1 Procedure A, without a metal catalyst, and

1.1.2 Procedure B, with a metal catalyst.

1.2 This test method is applicable to insulating liquids used as impregnating or pressure media in electrical power transmission cables if less than 10 % of the insulating liquid evaporates during the aging procedures. It applies and is generally useful primarily in the evaluation and quality control of unused insulating liquids, either inhibited or uninhibited.

1.3 This test method is applicable to study the long-term behavior of an insulating liquid being considered for free breathing transformers. An unsealed vessel aging procedure, in presence of air or oxygen, allows greatly increased oxidation rate of the liquid. This procedure is rapid and provides a controlled thermal stress assessment.

1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

1.5 An open beaked test shall only be carried out on liquids with flash points at or above 130°C or 15°C above the oven temperature. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. See 7.5 for a specific warning statement.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.