ASTM_D_831_-_D_831M_-_12.pdf

Designation:D831/D831M12Standard Test Method forGas Content of Cable and Capacitor Oils1This standard is issued under the fixed designation D831/D831M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the gascontent of electrical insulating oils of low and mediumviscosities in the general range up to 190 mm2/s at 104F40C,such as are used in capacitors and paper-insulatedelectric cables and cable systems of the oil-filled type.Thedetermination of gas content is desirable for any insulating oilhaving these properties and intended for use in a degassedstate.NOTE1For testing insulating oils with viscosities of 19 mm2/s orbelow at 40C,see Test Method D2945.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.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 applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D2945 Test Method for Gas Content of Insulating Oils2(Withdrawn 2012)23.Summary of Test Method3.1 This test method consists essentially of feeding the oilinto an evacuated chamber in such a manner that the oil isthoroughly exposed to the vacuum,allowing free escape of anydissolved gas.From the volume of oil admitted to the chamber,the temperature,the pressure produced,and volume occupiedby the released gas,the gas volume under standard conditionsof pressure and temperature may be calculated as a percentageby volume of oil.4.Significance and Use4.1 The gas content of cable and capacitor oils is consideredto be important,since the evolution of gas in the form ofbubbles can have an adverse effect on the insulating propertiesof these fluids.It is customary to degas these oils prior to use,and this test method provides a means of determining the gascontent before and after degassing.5.Apparatus(see Fig.1)5.1 Degassing ChamberDegassing chamber,A,made ofheat-resistant glass4(with calibrated oil well at bottom),havinga fixed total space volume of about 175 to 300 mL.The oil wellshall have a maximum capacity of 50 mL and shall becalibrated in 0.2-mL divisions.5.2 StopcocksGlass stopcocks,B and C,which shall havelarge-diameter barrels and a mirror finish to ensure againstleakage.Use stopcock grease5on all stopcocks and ground-glass joints.5.3 AtomizerGlass pipet,D,placed to drop oil on the sideof the degassing chamber,or5.3.1 Fritted Disk(Alternative)Capacity 30 mm,medium-porosity.NOTE2Some experience has shown improvement in the atomizationprocess,particularly for oils of medium viscosity above 95 mm2/s at 40C,if a 30-mm medium-porosity fritted disk is substituted for the pipet.5.4 Pressure Gage Pressure gage,E,of modified McLeodtype.6Include the volume of this gage in the over-all volume of1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-mittee D27.03 on Analytical Tests.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 1945.Last previous edition approved in 1994 as D831 94(2004).DOI:10.1520/D0831_D0831M-12.2For 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 standards Document Summary page onthe ASTM website.2The last approved version of this historical standard is referenced onwww.astm.org.4Borosilicate glass has been found to be satisfactory for this purpose.5Astopcock grease equivalent to No.15521.Areadily available vacuum sealingcompound.Dow Corning grease#1597418,has been found to be satisfactory forthis use.6A McLeod gauge Flosdorf modification,available from Sigma-AldrichCompany,has been found satisfactory for this purpose.The sole source of supply ofthe apparatus known to the committee at this time is Sigma-Aldrich Company.Ifyou are aware of alternative suppliers,please provide this information to ASTMInternational Headquarters.Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 the apparatus(Note 3).This is essential and must also includethe volume of the gage-connecting tubing.NOTE3The volume of the gage may