【国外标准】 Standard Test Method for Determination of Methanol and Ethanol in Electrical Insulating Liquids of Petroleum Origin by Headspace (HS)-Gas Chromatography (GC) Using Mass Spectrometry (MS) or Flame Ionization Detection (FID)

5.1 Methanol and ethanol are generated by the degradation of cellulosic materials used in the solid insulation systems of electrical equipment. More particularly, methanol comes from the depolymerization of cellulosic materials.3, 4, 5, 65.2 Methanol and ethanol, which are soluble in an insulating liquid to an appreciable degree, will proportionally migrate to that liquid after being produced from the cellulose.5.3 High concentrations or unusual increases in the concentrations of methanol or ethanol, or both, in an insulating liquid may indicate cellulose degradation from aging or incipient fault conditions. Testing for these alcohols may be used to complement dissolved gas-in-oil analysis and furanic compounds as performed in accordance with Test Methods D3612 and D5837 respectively.1.1 This test method describes the determination of by-products of cellulosic materials degradation found in electrical insulation systems that are immersed in insulating liquid. Such materials include paper, pressboard, wood and cotton materials. This test method allows the analysis of methanol and ethanol from the sample matrix by headspace GC-MS or GC-FID.1.2 This test method has been used to test for methanol and ethanol in mineral insulating liquids and less flammable electrical insulating liquids of mineral origin as defined in D3487 and D5222 respectively. Currently, this method is not a practical application for ester liquids.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 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.1.5 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.