ASTM_D_2798_-_21.pdf

Designation:D279821Standard 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 UnitsThe values stated in SI units are to be regardedas standard.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD388 Classification of Coals by RankD2797/D2797M Practice for Preparing Coal Samples forMicroscopical 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 x and 750 x,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 analyst1This 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 May 15,2021.Published June 2021.Originallyapproved in 1969.Last previous edition approved in 2020 as D2798 20.DOI:10.1520/D2798-21.2For 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1to move the specimen accurately(within 0.1 mm)to a givenfield location.A combination of objective and circular stageshall permit centering.The viewing eyepiece shal