1、Designation:D2945 90(Reapproved 2003)2Standard Test Method forGas Content of Insulating Oils1This standard is issued under the fixed designation D2945;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number
2、 in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEThe metric value for the inside diameter of vinyl tubing in Fig.1 was corrected editorially in December 2003.2NOTEThe mercury warning was editorially a
3、dded in April 2009.1.Scope1.1 This test method covers the determination of the gascontent of electrical insulating oils of low and mediumviscosities in the general range of 100 SUS and below at 100F(37.8C),and is suitable for field or laboratory use.NOTE1For testing insulating oils with viscosities
4、above 100 SUS,seeTest Method D831.For individual gas concentrations,see Method D3612.1.2 WarningMercury has been designated by EPA andmany state agencies as a hazardous material that can causecentral nervous system,kidney,and liver damage.Mercury,orits vapor,may be hazardous to health and corrosive
5、tomaterials.Caution should be taken when handling mercury andmercury-containing products.See the applicable product Ma-terial Safety Data Sheet(MSDS)for details and EPAs website(http:/www.epa.gov/mercury/faq.htm)for additional informa-tion.Users should be aware that selling mercury or mercury-contai
6、ning products,or both,in your state may be prohibited bystate law.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applic
7、a-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D831 Test Method for Gas Content of Cable and CapacitorOilsD3612 Test Method for Analysis of Gases Dissolved inElectrical Insulating Oil by Gas ChromatographyD3613 Practice for Sampling Insulating Liquids for G
8、asAnalysis and Determination of Water Content33.Summary of Test Method3.1 This test method consists essentially of allowing oil toflow into an evacuated chamber as a thin film so that the oil isthoroughly exposed to the vacuum,allowing free volatilizationof the gaseous component.The system is brough
9、t back toatmospheric pressure,and the evolved gases measured.Fromthe volume of oil degassed in the chamber and the volume ofreleased gas,the percent gas content may be estimated.Theapparatus used produces the necessary vacuum without resort-ing to use of a vacuum pump.This test method partiallydegas
10、es the oil.The degree of degasification varies with thesolubility of each gas in the oil.4.Significance and Use4.1 In filling electrical apparatus,it is desirable to use lowgas content transformer oil in order to prevent foaming and toavoid air pockets that might result in gaseous ionization.Thispro
11、cedure provides a simple method to measure the gas contentof the oil,and may be used as a factory-control test and as acontrol or functional test in installation and maintenance workby utilities.5.Apparatus5.1 Dissolved Gas Content AnalyserFig.1 shows theassembled instrument,not drawn to scale,to pe
12、rmit magnifi-cation of small details.A borosilicate glass gas buret,100-mLcapacity,graduated in15-mL divisions,serves as a vacuumchamber.A three-way stopcock,120 bore with TFE-fluorocarbon plug,3 stem,2-mm bore is fused to the buret orjoined by a vinyl sleeve so that the joint is vacuum tight.5.1.1
13、Rubber Vacuum TubingAbout 1200 mm of 8-mmrubber vacuum tubing is securely fastened with a 20-mmHoffman pinch clamp to the lower tip of the buret,while theother end is secured to a 250-mL capacity leveling bulb.5.1.2 Stubs 20 Gage NeedleA short section,about 40 mmlong,is cut and cemented to the three
14、-way stopcock,Fig.2.This serves to accommodate the vinyl tubing attached to the1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.03 on Analytical Tests.Current edition approved Feb.23,1990
15、.Published April 1990.Originallypublished as D2945 71.Last previous edition D2945 84.DOI:10.1520/D2945-90R03E02.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the stand
16、ards Document Summary page onthe ASTM website.3Withdrawn.The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest informationsyringe.All the glassware should be clamped to a suitable 1500by 700 by 20-mm mounting board
