ASTM D1533 - Water in Insulating Liquids by Coulometric Karl Fischer Titration

Significance and Use

4.1 Electrical characteristics of an insulating liquid may be affected deleteriously by excessive water content. A high water content may make a dielectric liquid unsuitable for some electrical applications due to deterioration of properties such as the dielectric breakdown voltage.

4.2 This test is suitable for use in acceptance specifications, in control of processing, and in evaluating the condition of dielectric liquids in service.

Scope

1.1 This test method covers the measurement of water present in insulating liquids by coulometric Karl Fischer titration. This test method is used commonly for test specimens below 100 % relative saturation of water in oil. The coulometric test method is known for its high degree of sensitivity.

(typically 10 µg H2O). This test method requires the use of equipment specifically designed for coulometric titration.

1.2 This test method recommends the use of commercially available coulometric Karl Fischer titrators and reagents.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

Extracted, with permission, from ASTM D1533-20 - Water in Insulating Liquids by Coulometric Karl Fischer Titration, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be purchased from ASTM International, astm.org