ASTM_E_1491_-_06_2012.pdf

Designation:E149106(Reapproved 2012)Standard Test Method forMinimum Autoignition Temperature of Dust Clouds1This standard is issued under the fixed designation E1491;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 covers the determination of the minimum temperature at which a dust cloud willautoignite.The dust cloud is exposed to air heated to various temperatures in a furnace.Ignition of thecloud is indicated by visual observation of the flame.The chemical nature of the dust as well as itsconcentration,particle size,moisture,and surface area affects the results.1.Scope1.1 This test method covers the minimum temperature atwhich a given dust cloud will autoignite when exposed to airheated in a furnace at local atmospheric pressure.1.2 Data obtained from this test method provide a relativemeasure of dust cloud autoignition temperatures.1.3 This test method should be used to measure and describethe properties of materials,products,or assemblies in responseto heat and flame under controlled laboratory conditions andshould not be used to describe or appraise the fire hazard or firerisk of materials,products,or assemblies under actual fireconditions.However,results of this test method may be used aselements of a fire risk assessment which takes into account allof the factors which are pertinent to an assessment of the firehazard of a particular end use.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.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 CokeE659 Test Method for Autoignition Temperature of LiquidChemicalsE1226 Test Method for Explosibility 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 minimum autoignition temperature(MAIT)the mini-mum temperature at which a dust cloud will self ignite underthe specified conditions of test.4.Summary of Test Method4.1 The temperature of the furnace or oven is set at apredetermined value.4.2 Dust is blown into the heated furnace,which is atambient pressure.4.3 Ignition is determined by visual observation of the flameexiting the furnace.5.Significance and Use5.1 This test method provides a procedure for performinglaboratory tests to determine the minimum autoignition tem-perature(MAIT)of a dust cloud.5.2 The test data developed from this test method can beused to limit the temperature to which a dust cloud is exposedso as to prevent ignition of the cloud.Because of the shortduration of the test,the data obtained are most applicable toindustrial equipment where dust is present as a cloud for a shorttime.Because of the small scale of the test and the possible1This 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.1,2012.Published December 2012.Originallyapproved in 1991.Last previous edition approved in 2006 as E1491 06.DOI:10.1520/E1491-06R12.2For 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 variation of the MAIT value with scale,the data obtained bythis test method may not be directly applicable to all industrialconditions.5.3 The MAIT data can also be used in conjunction withminimum spark ignition data to evaluate the hazards ofgrinding and impact sparks in the presence of dust clouds(1and 2).35.4 The test values obtained are specific to the sampletested,the method used,and the test equipment utilized.Thetest values are not to be considered intrinsic material constants,but may be used as a relative measure of the temperature atwhich a dust cloud self ignites.5.5 The test data are for cloud ignition.Dust in the form ofa layer may ignite at significantly lower temperatures than thesame dust in the form of a cloud(3).For liquid chemicals,seeTest Method E659.6.Interferences6.1 Unburned dust from a previous test may affect results.Ifthere is