ASTM_D_1807_-_00_2005e1.pdf

Designation:D180700(Reapproved 2005)1Standard Test Methods forRefractive Index and Specific Optical Dispersion ofElectrical Insulating Liquids1This standard is issued under the fixed designation D1807;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEThe word“containment”was corrected to“contaminant”in the second sentence of 4.1 editorially in December2009.1.Scope1.1 These test methods cover the determination of therefractive index and the specific optical dispersion of electricalinsulating liquids such as are used in capacitors,transformers,circuit breakers,and oil-filled cables.1.2 Two test methods are described,a routine method and amore precise referee method.Both methods are applicable totransparent,light-colored,insulating liquids.1.2.1 The routine method is used to determine refractiveindex and specific optical dispersion as described in these testmethods.1.2.2 The referee method is used when a test of highaccuracy is desired.These methods are described in TestMethod D1218.Specific optical dispersion is calculated bydividing the refractive dispersion value determined in TestMethod D1218 by the relative density(specific gravity)(seeTest Method D1298)of the liquid under test.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 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:2D1218 Test Method for Refractive Index and RefractiveDispersion of Hydrocarbon LiquidsD1298 Test Method for Density,Relative Density(SpecificGravity),or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer Method3.Terminology3.1 Definitions:3.1.1 refractive index,nthe ratio of the velocity of light inair to its velocity in the substance under test.3.1.2 relative density(specific gravity),nthe ratio of themass of a given volume of liquid at 15C(60F)to mass of anequal volume of pure water at the same temperature.3.1.3 specific optical dispersion,nthe difference betweenthe refractive indexes of light of two different wavelengths,both indexes measured at the same temperature,and divided bythe relative density(specific gravity),also measured at the testtemperature.4.Significance and Use4.1 Refractive IndexThe refractive index of an insulatingliquid varies with its composition and with the nature andamount of contaminants held in solution.Changes of refractiveindex with time and service may form a basis for estimatingany change in composition or the degree of contaminantacquired in service.For electrical insulating mineral oils,thewavelength of 5893 A for the spectral line of sodium iscommonly used.The test temperature is 25C.4.2 Specific Optical Dispersion Specific optical disper-sion serves as a quick index to the amount of unsaturatedcompounds present in an oil.Dispersion values for paraffinicand naphthenic compounds are nearly the same and areessentially independent of molecular weight and structuraldifferences.Values above 97 bear a direct relationship to theamount of aromatic compounds present in insulating oil.Forconvenience,the specific dispersion value is multiplied by104.For electrical insulating mineral oils,the wavelengths of6563 and 4861 A corresponding to the spectral lines ofhydrogen are commonly used.Alternatively,the wavelengthsof 6678 and 5016 A corresponding to the spectral lines ofhelium may be used.1These test methods are under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gasesand are the direct responsibility of Subcom-mittee D27.07 on Physical Test.Current edition approved Oct.1,2005.Published November 2005.Originallyapproved in 1960.Last previous edition approved in 2000 as D1807 00.DOI:10.1520/D1807-00R05E01.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesNOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest information15.Apparatus5.1 RefractometerThe refractometer to be used in theroutine method shall have an index range of approximately1.33 to 1.5 and be readable to 60.0002 units.The refractome-ter used in the referee method is described in Test MethodD1218.5.2 Light SourceA suitable incandescent illu