ASTM E1232-2007 Standard Test Method for Temperature Limit of Flammability of Chemicals《化学制品可燃性的温度限度用标准试验方法》.pdf

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1、Designation: E 1232 07Standard Test Method forTemperature Limit of Flammability of Chemicals1This standard is issued under the fixed designation E 1232; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n

2、umber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe temperature limit of flammability test measures the minimum temperature at which liquid (orsolid) chemicals evolve sufficient vapor

3、s to form a flammable mixture with air under equilibriumconditions. This temperature is applicable for assessing flammability in large process vessels andsimilar equipment (Appendixes Appendix X1 and Appendix X2).1. Scope1.1 This test method covers the determination of the mini-mum temperature at wh

4、ich vapors in equilibrium with a liquid(or solid) chemical will be sufficiently concentrated to formflammable mixtures in air at atmospheric pressure. This testmethod is written specifically for determination of the tempera-ture limit of flammability of systems using air as the source ofoxidant and

5、diluent. It may also be used for other oxidant/diluent combinations, including air plus diluent mixtures;however, no oxidant/diluent combination stronger than airshould be used. Also, no unstable chemical capable of explo-sive decomposition reactions should be tested (see 8.3).1.2 This test method i

6、s designed and written to be run atlocal ambient pressure and is limited to a maximum initialpressure of 1 atm abs. It may also be used for reduced pressureswith the practical lower pressure limit being approximately13.3 kPa (100 mm Hg). The maximum practical operatingtemperature of this equipment i

7、s approximately 150 C (302F) (Note A1.2).1.3 The values stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses areprovided for information only.1.4 This standard should be used to measure and describethe properties of materials, products, or assemblies in res

8、ponseto 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 may be used aselements of a fire risk assessment which takes into

9、account allof the factors which are pertinent to an assessment of the firehazard of a particular end use.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

10、 health practices and determine the applica-bility of regulatory limitations prior to use. Specific safetyprecautions are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D 3278 Test Methods for Flash Point of Liquids by SmallScale Closed-Cup ApparatusD 3828 Test Methods for Flash Point

11、 by Small Scale ClosedCup TesterD 3941 Test Method for Flash Point by the EquilibriumMethod With a Closed-Cup ApparatusE 220 Test Method for Calibration of Thermocouples ByComparison TechniquesE 230 Specification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE 502 Tes

12、t Method for Selection and Use of ASTM Stan-dards for the Determination of Flash Point of Chemicals byClosed Cup MethodsE 537 Test Method for The Thermal Stability Of ChemicalsBy Differential Scanning CalorimetryE 681 Test Method for Concentration Limits of Flammabil-ity of Chemicals (Vapors and Gas

13、es)E 698 Test Method for Arrhenius Kinetic Constants forThermally Unstable Materials Using Differential ScanningCalorimetry and the Flynn/Wall/Ozawa Method2.2 ANSI Standard:ANSI-MC96.1 Temperature Measurement Thermocouples31This test method is under the jurisdiction of ASTM Committee E27 on HazardPo

14、tential of Chemicals and is the direct responsibility of Subcommittee E27.04 onFlammability and Ignitability of Chemicals.Current edition approved Oct. 1, 2007. Published November 2007 . Originallyapproved in 1991. Last previous edition approved in 2002 as E 123202.2For referenced ASTM standards, vi

15、sit 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 American National Standards Institute, 1430 Broadway, NewYork, NY 10018.1Copyri

16、ght ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.3 NFPA Standard:NFPA 325 Fire Hazardous Properties Liquids33. Terminology3.1 Definitions:3.1.1 flash pointthe lowest temperature, corrected to apressure of 101.3 kPa (760 mm Hg, 1013 mbar),

17、at whichapplication of an ignition source causes the vapors of thespecimen to ignite under specified conditions of test.3.1.2 lower limit of flammability or lower flammable limit,(LFL)the minimum concentration of a combustible sub-stance that is capable of propagating a flame through ahomogeneous mi

18、xture of the combustible and a gaseousoxidizer under the specified conditions of test.3.1.3 lower temperature limit of flammability, (LTL)thelowest temperature, corrected to a pressure of 101.3 kPa (760mm Hg, 1013 mbar), at which application of an ignition sourcecauses a homogeneous mixture of a gas

19、eous oxidizer andvapors in equilibrium with a liquid (or solid) specimen to igniteand propagate a flame away from the ignition source under thespecified conditions of test.3.2 Definition of Term Specific to This Standard:3.2.1 propagation of flamethe upward and outward move-ment of the flame front f

20、rom the ignition source to the vesselwalls, that is determined by visual observation.4. Summary of Test Method4.1 A pool of liquid is stirred in a closed vessel in an airatmosphere. The vapor-air mixture above this liquid is exposedto an ignition source and the upward and outward propagationof flame

21、 away from the ignition source is noted by visualobservation. Temperature in the test vessel is varied betweentrials until the minimum temperature at which flame willpropagate away from the ignition source is determined.5. Significance and Use5.1 The lower temperature limit of flammability is themin

22、imum temperature at which a liquid (or solid) chemical willevolve sufficient vapors to form a flammable mixture with airunder equilibrium conditions. Knowledge of this temperatureis important in determining guidelines for the safe handling ofchemicals, particularly in closed process and storage vess

23、els.NOTE 1As a result of physical factors inherent in flash point appara-tus and procedures, closed-cup flash point temperatures are not necessarilythe minimum temperature at which a chemical will evolve flammablevapors (see Appendix X2 and Appendix X3, taken in part from TestMethod E 502). The temp

24、erature limit of flammability test is designed tosupplement limitations inherent in flash point tests (Appendix X2). Ityields a result closely approaching the minimum temperature of flam-mable vapor formation for equilibrium situations in the chemical process-ing industry such as in closed process a

25、nd storage vessels.NOTE 2As a result of flame quenching effects existing when testing instandard closed-cup flash point apparatus, there are certain chemicals thatexhibit no flash point but do evolve vapors that will propagate a flame invessels of adequate size (X3.2). The temperature limit of flamm

26、ability testchamber is sufficiently large to overcome flame quenching effects in mostcases of practical importance, thus, usually indicating the presence ofvapor-phase flammability if it does exist (6.2).NOTE 3The lower temperature limit of flammability (LTL) is onlyone of several characteristics th

27、at should be evaluated to determine thesafety of a specific material for a specific application. For example, somematerials are found to have an LTL by this test method when, in fact, othercharacteristics such as minimum ignition energy and heat of combustionshould also be considered in an overall f

28、lammability evaluation.5.2 The vapor concentration present at the lower tempera-ture limit of flammability equals the lower flammable limitconcentration as measured by Test Method E 681 and extrapo-lated back to the same temperature. (This permits estimation oflower temperature limits of flammabilit

29、y if vapor pressure andconcentration limit of flammability data are available (A2.3).Acomparison of results of the tests, thus, affords a check on testreliability, the reliability of vapor pressure data, or both.)6. Interferences6.1 This test method is not applicable to materials thatundergo chemica

30、l changes when mixed with air. Examplesinclude, but are not limited to, oxidation and polymerization.6.2 Measured temperature limits are influenced by flamequenching effects of the test vessel walls. The test vesselemployed in this test method is of sufficient size to eliminatethese effects for most

31、 materials. For certain amines, haloge-nated materials, etc., that have large ignition-quenching dis-tances, tests should be conducted in vessels with largerdiameters than the one listed in this test method (A1.1).Quenching effects become increasingly significant as the testpressure decreases.6.3 Me

32、asured temperature limits of flammability of chemi-cals can be greatly influenced, as are flash points, by thepresence of various impurities or known mixture components.Small quantities of volatile flammable impurities can reducetemperature limit values, and volatile inert diluents can raisetemperat

33、ure limit values or produce complete inerting. (See8.2.3 and Annex A3 for a discussion of mixture testing.)7. Apparatus7.1 Fig. 1 is a schematic diagram of the apparatus; detailsand dimensions are presented in Annex A1. The apparatusconsists of the following:7.1.1 Glass Test Vessel,7.1.2 Insulated C

34、hamber, equipped with a source ofcontrolled-temperature air,7.1.3 Ignition Device, with an appropriate power supply,and7.1.4 Magnetic Stirrer and Cover, equipped with the neces-sary operating connections and components.8. Hazards8.1 Tests should not be conducted in this apparatus withgaseous oxidant

35、s stronger than air since explosive violenceincreases as oxidizer strength increases. Do not use oxygen,nitrous oxide, nitrogen dioxide, chlorine, etc. in this glassapparatus.8.2 Adequate shielding must be provided to prevent injuryin the event of equipment rupture, due to both implosions andexplosi

36、ons. A metal enclosure such as that recommended inA1.2 is one method suitable for this purpose.8.2.1 Implosion of the test vessel at high vacuum levels ispossible and, therefore, all evacuations must be made with therequired shielding to protect against flying fragments.E12320728.2.2 Energetic explo

37、sions may be produced if tests aremade at temperatures above the LTL. The determination of theLTL should always be initiated at a temperature below theestimated LTL, and successive ignition trials made at intervalsof not more than a 2C temperature increase. Methods forestimating initial test tempera

38、tures, discussed in Annex A2,should be employed to ensure that initial trials are conducted attemperatures less than the LTL (Note 4). The glass test vessel,equipped with a lightly held or loose cover, vents mostexplosions adequately. Nevertheless, shielding is required toprotect against any possibi

39、lity of test vessel rupture.8.2.3 The testing of materials that are reactive with themetal parts of the apparatus can effect results, and may causeenergetic explosions. For example, acids and alkaline materialscan generate hydrogen gas. When testing such materials,variable results due to the generat

40、ion of hydrogen may bedetected by varying the holding time of several trials at aspecific temperature. If corrosion occurs, materials of construc-tion should be changed to corrosion resistant types.8.2.4 Testing should be carried out in a manner that preventsaccidental activation of the ignition sou

41、rce at incorrect stagesof the procedure.8.3 Tests should not be conducted on peroxides, monopro-pellants, or other thermally unstable materials that mightundergo explosive gas or liquid phase decomposition reactions.For example, some monomers may undergo energetic vaporphase polymerization reactions

42、. For information on evaluatingthe thermal stability of proposed test materials, see DS-51A,and Test Methods E 537 and E 698.8.4 Tests should be conducted in a fume hood or otherventilated area to prevent exposure of personnel to toxicchemicals or combustion products.8.5 Precautions must be taken to

43、 ensure that the highvoltage spark ignition source is always adequately insulatedfrom other electrical circuits and metal parts of the apparatus,fume hood, etc. to prevent electrical hazards to personnel andinstrumentation. Careful attention to electrical insulation integ-rity plus the use of discon

44、nection procedures are required toachieve a satisfactory protection against electrical hazards.9. Calibration9.1 System temperature and pressure and barometric pres-sure measuring devices must be calibrated against adequatestandards. For information on calibration of thermocouples, seeMethod E 220,

45、Specification E 230, and ANSI-MC96.1. Thepressure sensing devices should be calibrated against a trace-able standard such as a primary standard piston gage, com-monly called a dead weight gage.10. Procedures10.1 Lower Temperature Limit of Flammability Test10.1.1 Assemble the equipment, as shown in F

46、ig. 1, withinan appropriate fume hood or other ventilated area and securethe door of the metal enclosure. Clean and dry the test vesselFIG. 1 Schematic Diagram of Test ApparatusE1232073and all components. Evacuate the system and flush with air, orother specified test gas, sufficiently to ensure remo

47、val ofresidual volatile materials that may be present as a result ofcleaning or prior tests.10.1.2 Based on methods given in Annex A2, adjust theflask to the desired test temperature below the anticipatedlower temperature limit of flammability.NOTE 4A prudent operator will use a wide safety factor i

48、n choosinginitial test temperatures (6.3). This may necessitate a few additional trialsbut will provide increased safety for the operation.10.1.3 It may be necessary to separately heat, insulate, orheat and insulate cover components and lines, to prevent vaporcondensation at cool sites within the va

49、por space. The liquid,mist, or both, that may otherwise be formed can causeerroneous results.10.1.4 Make certain that all safety precautions have beentaken.10.2 Sample Introduction of Liquids:10.2.1 Introduce 50 cm3of liquid to the flask using aseparatory funnel or other inlet device.NOTE 5The 50 cm3of liquid provide substantially more than theo-retically required. Smaller sample sizes are adequate for pure chemicalsand larger sample sizes may be required for mixtures (Annex A3).10.2.2 Turn on the stirrer at a speed of approximately 400rpm.10.2.3 Close the hood door. (Cov