ASTM_D_2798_-_11a.pdf

Designation:D279811aStandard Test Method forMicroscopical Determination of the Vitrinite Reflectance ofCoal1This standard is issued under the fixed designation D2798;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.1.Scope1.1 This test method covers the microscopical determinationof both the mean maximum and mean random reflectancesmeasured in oil of polished surfaces of vitrinite and othermacerals present in coals ranging in rank from lignite toanthracite.This test method can be used to determine thereflectance of other macerals.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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:2D121 Terminology of Coal and CokeD388 Classification of Coals by RankD2797 Practice for Preparing Coal Samples for Microscopi-cal Analysis by Reflected Light3.Terminology3.1 DefinitionsFor definitions of terms,refer to Terminol-ogy D121.3.2 Abbreviations:3.2.1 Romaxmean maximum reflectance measured in oil.3.2.2 Roranmean random reflectance measured in oil.3.2.2.1 DiscussionOther organizations may use other ab-breviations for mean maximum and mean random reflectance.4.Summary of Test Method4.1 The reflectance of the maceral vitrinite or other maceralsis determined in this test method by illuminating a polishedsurface of a section of coal in immersion oil using a micro-scopic system that photometrically measures the amount oflight reflected from the surface.The reflected light is recordedin percent reflectance after calibration of photometric equip-ment by measuring the reflected light from standards ofreflectance as calculated from their refractive indices.5.Significance and Use5.1 The mean maximum reflectance of the vitrinite compo-nent in coal as determined by this test method is often used asan indicator of rank as presented in Classification D388,independent of petrographic composition,and in the charac-terization of coal as feedstock for carbonization,gasification,liquefaction,and combustion processes.5.2 This test method is for use in scientific and industrialresearch.6.Apparatus6.1 MicroscopeAny microscope equipped for reflectedlight microscopy(such as a metallurgical or opaque-ore mi-croscope)can be used,provided the lens combination ofobjective and eyepieces permits examination of the specimenat a magnification between 400 and 750,such that particlesof 1 m can be resolved.The objectives shall be constructed sothat samples can be examined in oil with plane-polarized lightand have the highest quality of antireflection coatings.Themicroscope shall be able to project an image at similarmagnification to a photomultiplier tube and to support thephotomultiplier tube housing.Means shall be provided toposition the tube housing laterally to obtain maximum re-sponse.The microscope shall have a circular stage that iscapable of rotating a specimen through 360.The mechanicalstage attached to the microscope stage shall enable the analystto move the specimen accurately(within 0.1 mm)to a givenfield location.A combination of objective and circular stageshall permit centering.The viewing eyepiece shall be suppliedwith a crosshair or grid to be used as a reference to locateprecisely the area sampled by the phototube.During1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.28 on PetrographicAnalysis of Coal and Coke.Current edition approved June 1,2011.Published July 2011.Originally approvedin 1969.Last previous edition approved in 2011 as D2798 11.DOI:10.1520/D2798-11A.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 States1 measurement,no light shall be permitted to enter the observ-ers end of the viewing eyepiece.6.2 Polarizer and IlluminatorThe light incident on thevertical illuminator of the microscope shall be plane-polarizedby a prism or sheet polarizer.The vertical illuminator cancontain a Berek prism,a Smith illuminator,or high-qualityglass plate.The polarizer shall be oriented at 45 when using aBerek prism or at 0 when using a Smith illuminator or glassplate.6.3 Photomultiplier TubeIn combination with the micro-scope optical system,light sour