ASTM_E_2931_-_13.pdf

Designation:E293113Standard Test Method forLimiting Oxygen(Oxidant)Concentration of CombustibleDust Clouds1This standard is issued under the fixed designation E2931;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 is designed to determine the limitingoxygen concentration of a combustible dust dispersed in amixture of air with an inert/nonflammable gas in a near-spherical closed vessel of 20 L or greater volume.1.2 Data obtained from this 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 CokeE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE1226 Test Method for Explosibility of Dust CloudsE1515 Test Method for Minimum Explosible Concentrationof Combustible DustsE2079 Test Methods for Limiting Oxygen(Oxidant)Con-centration in Gases and Vapors2.2 NFPA Publications:3NFPA 69 Standard on Explosion Prevention Systems2.3 CEN/CENELEC Publications:4EN 140344 Determination of the explosion characteristicsof dust cloudsPart 4:Determination of the limitingoxygen concentration LOC of dust clouds3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 dust concentrationthe mass of dust divided by theinternal volume of the test chamber.3.1.2 limit of flammabilitythe boundary in compositionspace dividing flammable and nonflammable regions.3.1.3 limiting oxygen(oxidant)concentration(LOC)of afuel-oxidant-inert systemthe oxygen(oxidant)concentrationat the limit of flammability for the worst case(most flammable)fuel concentration.3.1.3.1 DiscussionThe Limiting Oxygen(oxidant)Con-centration is sometimes also known as Minimum Oxygen(oxidant)Concentration or as Critical Oxygen(oxidant)Con-centration.3.1.4 Pignitionthe absolute pressure at the time the ignitoris activated,see Fig.1.3.1.5 Pignitorthe pressure rise in the chamber due to theignitor by itself in air at atmospheric pressure.3.1.6 Pex,athe maximum explosion pressure(absolute)reached during the course of a single deflagration test.1This 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 June 1,2013.Published July 2013.DOI:10.1520/E2931-13.2For 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 National Fire Protection Association(NFPA),1 BatterymarchPark,Quincy,MA 02169-7471,http:/www.nfpa.org.4Available 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 3.1.7 pressure ratio(PR)defined asPR5Pex,a2 Pignitor!Pignition.3.1.8(dP/dt)exthe maximum rate of pressure rise duringthe course of a deflagration test.The rate of pressure rise canbe size-normalized by multiplying by the cube root of thechamber volume,givingd P d t!ex3V13.4.Summary of Test Method4.1 A dust cloud is formed in a closed combustion chamberby dispersion of the material with air and an inert gas(such asnitrogen,carbon dioxide,argon,etc.).The test is normallymade at atmospheric pressure and ambient temperature.Pro-portions of the gaseous components(oxygen and inert gas)aredetermined by a suitable means.4.2 Ignition of the mixture is attempted aft