1、Designation:D 1807 00Standard Test Methods forRefractive Index and Specific Optical Dispersion ofElectrical Insulating Liquids1This standard is issued under the fixed designation D 1807;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision
2、,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover the determination of therefractive index and the specific optical dispersion of elec
3、tricalinsulating 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
4、 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 D 1218.Specific optical dispersion is calculated bydividing the refractive dispersion valu
5、e determined in TestMethod D 1218 by the relative density(specific gravity)(seePractice D 1298)of the liquid under test.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is the
6、responsibility 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:D 1218 Test Method for Refractive Index and RefractiveDispersion of Hydrocarbon Liquids2D
7、 1298 Practice for Density,Relative Density(SpecificGravity),or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer Method23.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 de
8、nsity(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
9、 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 refractiv
10、eindex with time and service may form a basis for estimatingany change in composition or the degree of containmentacquired in service.For electrical insulating mineral oils,thewavelength of 5893 Afor the spectral line of sodium iscommonly used.The test temperature is 25C.4.2 Specific Optical Dispers
11、ionSpecific optical dispersionserves as a quick index to the amount of unsaturated com-pounds present in an oil.Dispersion values for paraffinic andnaphthenic compounds are nearly the same and are essentiallyindependent of molecular weight and structural differences.Values above 97 bear a direct rel
12、ationship to the amount ofaromatic compounds present in insulating oil.For convenience,the specific dispersion value is multiplied by 104.For electri-cal insulating mineral oils,the wavelengths of 6563 and 4861Acorresponding to the spectral lines of hydrogen are com-monly used.Alternatively,the wave
13、lengths of 6678 and 5016Acorresponding to the spectral lines of helium may be used.5.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 des
14、cribed in Test MethodD 1218.5.2 Light SourceA suitable incandescent illuminator shallbe used as a light source for determinations made by theroutine method;suitable light sources for the referee methodare described in Test Method D 1218.5.3 ThermostatA thermostat capable of supplying waterto the jac
15、keted prisms of the refractometer shall be capable ofmaintaining a temperature constant to within 60.1C.1These test methods are under the jurisdiction of ASTM Committee D-27 onElectrical Insulating Liquids and Gases and are the direct responsibility ofSubcommittee D27.07on Physical Tests.Current edi
16、tion approved April 10,2000.Published June 2000.Originallypublished as D 1807 60.Last previous edition D 1807 94.2Annual Book of ASTM Standards,Vol 05.01.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.6.Procedure for Routine Method6.1 Periodically check the adjustment of the refractometerwith the reference standard supplied with the instrument.6.2 Clean the instrument in accordance with the instructionsfurnished by the apparatus manufacturer before testing ea
