ASTM D1933-03(2017)
1.1 This specification covers three types of nitrogen used as an electrical insulating material in electrical equipment:
1.1.1 Type I, obtained from the air by liquefaction processes and dried,
1.1.2 Type II, obtained from the air by liquefaction processes, deoxidized with hydrogen over a platinum catalyst, and dried, and
1.1.3 Type III, obtained from the air by liquefaction processes and if necessary deoxidized by suitable means.
Note 1: The fact that metal containers are filled with materials meeting this specification does not exclude the possibility that the materials might become contaminated with unlisted impurities.
1.2 The following safety hazards caveat pertains only to the test method portion, Section 5, of this specification: 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.