Designation:D7569/D7569M−10(Reapproved2015)´1StandardPracticeforDeterminationofGasContentofCoal—DirectDesorptionMethod1ThisstandardisissuedunderthefixeddesignationD7569/D7569M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—DesignationwascorrectededitoriallyinFebruary2015.1.Scope1.1Thispracticedescribesmethodsforthedirectdetermi-nationofthegascontentofcoalbydesorptionusingsamplesobtainedbydrillcoringmethodsfromthesurface.Itsetsoutguidelinesfortheequipmentconstruction,samplepreparationandtestingprocedure,andmethodofcalculation.1.2Indirectmethodsforthedeterminationofthegascon-tentofcoal(notcoveredinthispractice)arebasedoneitherthegasabsorptioncharacteristicsofcoalunderagivenpressureandtemperatureconditionorotherempiricaldatathatrelatethegascontentofcoaltosuchotherparametersascoalrank,depthofcover,orgasemissionrate.1.3Thispracticecoversthefollowingtwodirectmethods,whichvaryonlyinthetimeallowedforthegastodesorbfromthecore,orsidewallcore,beforefinalcrushing:1.3.1Theslowdesorptionmethodinwhichvolumetricreadingsofgascontentaretakenfrequently(forexample,every10to15min)duringthefirstfewhours,followedbyhourlymeasurementsforseveralhours,andthenmeasure-mentson24-hintervalsuntilnoorverylittlegasisbeingdesorbedforanextendedperiodoftime.1.3.2Thefastdesorptionmethodinwhichafterinitialdesorbedgasmeasurementstoobtaindataforlostgascalcu-lationsaretaken,thecanisterisopenedandthesampleistransferredtothecoalcrusher.Theremaininggasvolumeismeasuredonacrushedsample.1.4Thispracticeisconfinedtothedirectmethodusingcore,orsidewallcoreobtainedfromdrilling.Thepracticecanbeappliedtodrillcuttingssamples;however,theuseofcuttingsisnotrecommendedbecausetheresultsmaybemisleadingandaredifficulttocomparetotheresultsobtainedfromcoredesorption.Theinterpretationoftheresultsdoesnotfallwit...
