1、Designation: E1232 07 (Reapproved 2013)Standard Test Method forTemperature Limit of Flammability of Chemicals1This standard is issued under the fixed designation E1232; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 s
3、ufficient vapors to form a flammable mixture with air under equilibriumconditions. This temperature is applicable for assessing flammability in large process vessels andsimilar equipment (Appendix X1 and Appendix X2).1. Scope1.1 This test method covers the determination of the mini-mum temperature a
4、t which 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
5、and 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 meth
6、od is 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 equipme
7、nt is approximately 150C (302F)(Note A1.2).1.3 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units are provided for informationonly and are not considered standard.1.4 This standard should be used to measure and
8、 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 tes
9、t 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.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibili
10、ty 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 safetyprecautions are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D3278 Test Methods for Flash Point of Liquids by
11、 SmallScale Closed-Cup ApparatusD3828 Test Methods for Flash Point by Small Scale ClosedCup TesterD3941 Test Method for Flash Point by the EquilibriumMethod With a Closed-Cup ApparatusE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE230 Specification and Temperature-Electrom
12、otive Force(EMF) Tables for Standardized ThermocouplesE502 Test Method for Selection and Use of ASTM Stan-dards for the Determination of Flash Point of Chemicalsby Closed Cup MethodsE537 Test Method for The Thermal Stability of Chemicalsby Differential Scanning CalorimetryE681 Test Method for Concen
13、tration Limits of Flammabilityof Chemicals (Vapors and Gases)E698 Test Method for Arrhenius Kinetic Constants forThermally Unstable Materials Using Differential Scan-ning Calorimetry and the Flynn/Wall/Ozawa Method1This test method is under the jurisdiction of ASTM Committee E27 on HazardPotential o
14、f Chemicals and is the direct responsibility of Subcommittee E27.04 onFlammability and Ignitability of Chemicals.Current edition approved Oct. 1, 2013. Published November 2013. Originallyapproved in 1991. Last previous edition approved in 2007 as E1232 07. DOI:10.1520/E1232-07R13.2For referenced AST
15、M 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 Conshohoc
16、ken, PA 19428-2959. United States12.2 ANSI Standard:3ANSI-MC96.1 Temperature Measurement Thermocouples2.3 NFPA Standard:4NFPA 325 Fire Hazardous Properties Liquids3. Terminology3.1 Definitions:3.1.1 flash pointthe lowest temperature, corrected to apressure of 101.3 kPa (760 mm Hg, 1013 mbar), at whi
17、chapplication 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 mixture
18、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 gaseous o
19、xidizer 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 Definitions of Terms Specific to This Standard:3.2.1 propagation of flamethe upward and outward move-ment of the flame front from
20、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 awa
21、y 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 theminimum
22、 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 vessels.
23、NOTE 1As a result of physical factors inherent in flash point apparatusand 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 E502). The temperature
24、 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 and stor
25、age 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 flammability
26、 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 only oneof several characteristics that shou
27、ld be evaluated to determine the safetyof 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 flammabi
28、lity 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 E681 and extrapo-lated back to the same temperature. (This permits estimation oflower temperature limits of flammability if vap
29、or 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 chemical change
30、s 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 materia
31、ls. For certain amines, haloge-nated materials, etc., that have large ignition-quenchingdistances, 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 Measured tem
32、perature 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 raisetemperature limit
33、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 Chamber, eq
34、uipped 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 oxidants stronger
35、 than air since explosive violenceincreases as oxidizer strength increases. Do not use oxygen,nitrous oxide, nitrogen dioxide, chlorine, etc. in this glassapparatus.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Availab
36、le from National Fire Protection Association (NFPA), 1 BatterymarchPark, Quincy, MA 02169-7471, http:/www.nfpa.org.E1232 07 (2013)28.2 Adequate shielding must be provided to prevent injury inthe event of equipment rupture, due to both implosions andexplosions. A metal enclosure such as that recommen
37、ded 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.8.2.2 Energetic explosions may be produced if tests aremade at temperatur
38、es 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 temperatures, discussed in Annex A2,should be employed to e
39、nsure 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 possibility of test vessel rupture.8.2.3 The testing of mat
40、erials 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 generation of hydrogen may bedetected by varying the holdin
41、g 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 source at incorrect stagesof the procedure.8.3 Tests sh
42、ould not be conducted on peroxides,monopropellants, or other thermally unstable materials thatmight undergo explosive gas or liquid phase decompositionreactions. For example, some monomers may undergo ener-getic vapor phase polymerization reactions. For information onevaluating the thermal stability
43、 of proposed test materials, seeDS-51A, and Test Methods E537 and E698.8.4 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 ensure that the highvoltage spark ignition source is
44、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 disconnection procedures are required toachieve a satisfacto
45、ry 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, seeFIG. 1 Schematic Diagram of Test ApparatusE1232 07 (2013)3Test Metho
46、d E220, Specification E230, and ANSI-MC96.1.The pressure sensing devices should be calibrated against atraceable standard such as a primary standard piston gage,commonly called a dead weight gage.10. Procedures10.1 Lower Temperature Limit of Flammability Test:10.1.1 Assemble the equipment, as shown
47、in Fig. 1, withinan appropriate fume hood or other ventilated area and securethe door of the metal enclosure. Clean and dry the test vesseland all components. Evacuate the system and flush with air, orother specified test gas, sufficiently to ensure removal ofresidual volatile materials that may be
48、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 in choosinginitial test temperatures (6.3). Thi
49、s 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 vapor 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
