ASTM E1491-2006 Standard Test Method for Minimum Autoignition Temperature of Dust Clouds《尘云的最低自燃温度的标准试验方法》.pdf
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1、Designation: E 1491 06Standard Test Method forMinimum Autoignition Temperature of Dust Clouds1This standard is issued under the fixed designation E 1491; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 t
3、o 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 temperat
4、ure 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 m
5、aterials, 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 aselemen
6、ts 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 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
7、 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:2D 3173 Test Method for Moisture in theAnalysis Sample ofCoal and CokeD 3175 Test Method for Volatile Matter in the Analys
8、isSample of Coal and CokeE 659 Test Method for Autoignition Temperature of LiquidChemicalsE 1226 Test Method for Pressure and Rate of Pressure Risefor Combustible Dusts3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 dust concentrationthe mass of dust divided by theinternal vol
9、ume 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 hea
10、ted 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
11、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 to1This test method is under the jurisdiction of ASTM Committee E27 on
12、 HazardPotential of Chemicals and is the direct responsibility of Subcommittee E27.05 onExplosibility and Ignitability of Dust Clouds.Current edition approved Oct. 1, 2006. Published November 2006. Originallyapproved in 1991. Last previous edition approved in 2002 as E 1491 97(2002).2For referenced
13、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consh
14、ohocken, PA 19428-2959, United States.industrial equipment where dust is present as a cloud for a shorttime. Because of the small scale of the test and the possiblevariation of the MAIT value with scale, the data obtained bythis test method may not be directly applicable to all industrialconditions.
15、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 val
16、ues 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
17、cloud (3). For liquid chemicals, seeTest Method E 659.6. Interferences6.1 Unburned dust from a previous test may affect results. Ifthere is a question, the furnace should be heated to itsmaximum temperature to clean it before future tests are made.6.2 The material of construction of this test method
18、 mayhave catalytic effects on the ignition and should be consideredduring testing.7. Apparatus7.1 The equipment consists of a heated chamber closed witha frangible diaphragm, or flap vent, or a hole open to theatmosphere.7.2 The chamber is insulated and provided with a thermo-statically controlled e
19、lectric heater. A thermocouple measuresthe set temperature of the chamber.7.3 A dust dispersion system generates a fairly uniform dustcloud within the chamber. There should be a minimal amountof dust remaining in the disperser after the test.7.4 Athermocouple (1 mil or 25 m) and a recording systemha
20、ving a fast enough response may be used to measure thetemperature rise during ignition of the dust cloud in thechamber.7.5 Examples of chambers and specific procedures that havebeen found suitable are listed in chronological order inAppendix X1-Appendix X4.8. Hazards8.1 Safety Precautions:8.1.1 Prio
21、r to handling a dust, its toxicity and the toxicity ofits combustion products must be considered. This informationcan usually be obtained from the manufacturer. Considerationwill have to be given to ventilation, use of hoods, personalprotective gear, and procedures.8.1.2 Explosive, highly reactive,
22、or easily decomposed ma-terials should not be tested unless they have been characterizedby prior testing. Procedures such as the use of barricades,hoods, and personal protective equipment should be used asjudgment indicates.8.1.3 Electrical systems must be grounded.9. Sampling9.1 It is not practical
23、 to specify a single method of samplingdust for test purposes because the character of the material andits available form affect selection of the sampling procedure.Generally accepted sampling procedures should be used asdescribed in STP 447A.49.2 Tests may be run on an as-received sample. However,d
24、ue to the possible accumulation of fines at some location in aprocessing system, it is recommended that the test sample be atleast 95 % minus 200 mesh (75 m).9.3 To achieve this particle fineness (95 % minus 200mesh), grind, pulverize, or sieve the sample.NOTE 1The operator should consider the therm
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