ASTM D2685-11

Air and carbon tetrafluoride (CF₄) are two contaminants of interest in sulfur hexafluoride (SF₆). Both of these contaminants adversely affect the performance of SF₆ when used as an electrical insulating gas. Specification for maximum levels of these contaminants are given in Specification D2472.

Gas chromatography is used to separate these contaminants from a sample of SF₆ and to determine their concentration.

1.1 This test method covers the determination of air (Note 1) and carbon tetrafluoride as impurities in sulfur hexafluoride.

Note 1—Nitrogen, oxygen, or any of their mixtures is considered to be air. Commercial grade air or nitrogen is used for standardization.

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

1.3 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.