ASTM_E_1515_-_14.pdf

Designation:E151514Standard Test Method forMinimum Explosible Concentration of Combustible Dusts1This standard is issued under the fixed designation E1515;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.INTRODUCTIONThis test method describes procedures for measuring the minimum concentration of a combustibledust(dispersed in air)that is capable of propagating a deflagration.The tests are made in laboratorychambers that have volumes of 20 L or larger.1.Scope1.1 This test method covers the determination of the mini-mum concentration of a dust-air mixture that will propagate adeflagration in a near-spherical closed vessel of 20 L or greatervolume.NOTE1The minimum explosible concentration(MEC)is also re-ferred to as the lower explosibility limit(LEL)or lean flammability limit(LFL).1.2 Data obtained from this test method provide a relativemeasure of the deflagration characteristics of dust clouds.1.3 This test method should be used to measure and describethe properties of materials in response to heat and flame undercontrolled laboratory conditions and should not be used todescribe or appraise the fire hazard or fire risk of materials,products,or assemblies under actual fire conditions.However,results of this test may be used as elements of a fire riskassessment that takes into account all of the factors that arepertinent to an assessment of the fire hazard of a particular enduse.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 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.Specific precau-tionary statements are given in Section 8.2.Referenced Documents2.1 ASTM Standards:2D3173 Test Method for Moisture in the Analysis Sample ofCoal and CokeD3175 Test Method for Volatile Matter in the AnalysisSample of Coal and CokeE681 Test Method for Concentration Limits of Flammabilityof Chemicals(Vapors and Gases)E1226 Test Method for Explosibility of Dust Clouds2.2 CEN/CENELEC Publications:3EN 140343 Determination of Explosion Characteristics ofDust Clouds Part 3:Determination of the LowerExplosion Limit LEL of Dust Clouds3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 dust concentration,nthe mass of dust divided by theinternal volume of the test chamber.3.1.2(dP/dt)ex,nthe maximum rate of pressure rise duringthe course of a single deflagration test.3.1.3 minimum explosible concentration(MEC),ntheminimum concentration of a combustible dust cloud that iscapable of propagating a deflagration through a well dispersedmixture of the dust and air under the specified conditions oftest.3.1.4 Pignition,nthe absolute pressure at the time theignitor is activated,see Fig.1.3.1.5 Pignitor,nthe pressure rise in the chamber due tothe ignitor by itself in air at atmospheric pressure1This test method is under the jurisdiction of ASTM Committee E27 on HazardPotential of Chemicals and is the direct responsibility of Subcommittee E27.05 onExplosibility and Ignitability of Dust Clouds.Current edition approved Dec.1,2014.Published January 2015.Originallyapproved in 1993.Last previous edition approved in 2007 as E1515 07.DOI:10.1520/E1515-14.2For 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.3Available from European Committee for Standardization(CEN),AvenueMarnix 17,B-1000,Brussels,Belgium,http:/www.cen.eu.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.6 Pex,a,nthe maximum explosion pressure(absolute)reached during the course of a single deflagration test(see Figs.1 and 2).3.1.7 Pm,nmaximum pressure rise produced during thecourse of a single deflagration test that is corrected for theeffects of ignitor pressure and cooling in the 20-L vessel(seeTest Method E1226,Sections X1.8 and X1.9).3.1.7.1 DiscussionWhen testing in the Siwek 20-L vessel(see Test Method E1226,Appendix X1)PR may be calculatedusing the corrected explosion pressure:PR 5Pm1 Pignition!Pignition(1)3.1.8 pressure ratio(PR),ndefined as:PR 5Pex,a1 Pignitor!Pignition(2)4.Summary of Test Method4.1 A dust cloud is formed in a closed combustion chamberby an introduction of the material with air.The test is normallymade at atmospheric pressure.4.2 Ignition of this dust-air mixture is then attempted after aspecified delay time by an ignition source located near thecenter of the cham