ASTM E659-1978(2005) Standard Test Method for Autoignition Temperature of Liquid Chemicals《液体化学品自燃温度的试验方法》.pdf

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1、Designation: E 659 78 (Reapproved 2005)Standard Test Method forAutoignition Temperature of Liquid Chemicals1This standard is issued under the fixed designation E 659; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last

2、 revision. A 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 is one of several methods developed by ASTM Committee E-27 for determiningthe hazards of chemicals. It i

3、s designed to be used in conjunction with other tests to characterize thehazard potential of the chemical under test.1. Scope1.1 This test method covers the determination of hot- andcool-flame autoignition temperatures of a liquid chemical in airat atmospheric pressure in a uniformly heated vessel.N

4、OTE 1Within certain limitations, this test method can also be used todetermine the autoignition temperature of solid chemicals which readilymelt and vaporize at temperatures below the test temperature.1.2 This standard should be used to measure and describethe properties of materials, products, or a

5、ssemblies in responseto heat and flame under controlled laboratory conditions andshould not be used to describe or appraise the fire hazard orfire risk of materials, products, or assemblies under actual fireconditions. However, results of this test may be used aselements of a fire risk assessment wh

6、ich takes into account allof the factors which are pertinent to an assessment of the firehazard of a particular end use.2. Referenced Documents2.1 ASTM Standards:D 2883 Test Method for Reaction Threshold Temperatureof Liquid and Solid Materials23. Terminology3.1 Definitions:3.1.1 ignition, n the ini

7、tiation of combustion.3.1.2 Ignition, which is subjective, is defined for thismethod as the appearance of a flame accompanied by a sharprise in the temperature of the gas mixture. The determination ismade in total darkness because some flames, such as cool-flames, are observed with difficulty.3.2 au

8、toignition, nthe ignition of a material commonly inair as the result of heat liberation due to an exothermicoxidation reaction in the absence of an external ignition sourcesuch as a spark or flame.3.3 autoignition temperature, nthe minimum temperatureat which autoignition occurs under the specified

9、conditions oftest.3.3.1 Autoignition temperature is also referred to as spon-taneous ignition temperature, self-ignition temperature, autog-enous ignition temperature, and by the acronyms AIT and SIT.As determined by this method,AIT is the lowest temperature atwhich the substance will produce hot-fl

10、ame ignition in air atatmospheric pressure without the aid of an external energysource such as spark or flame. It is the lowest temperature towhich a combustible mixture must be raised, so that the rate ofheat evolved by the exothermic oxidation reaction will over-balance the rate at which heat is l

11、ost to the surroundings andcause ignition.3.4 cool-flame, na faint, pale blue luminescence or flameoccurring below the autoignition temperature (AIT).NOTE 2Cool-flames occur in rich vapor-air mixtures of most hydro-carbons and oxygenated hydrocarbons. They are the first part of themultistage ignitio

12、n process.3.5 ignition delay time, nthe time lapse between applica-tion of heat to a material and its ignition. It is the time inseconds between insertion of the sample into the flask andignition. It is maximum at the minimum autoignition tempera-ture and also referred to as ignition lag.4. Summary

13、of Test Method4.1 A small, metered sample of the product to be tested isinserted into a uniformly heated 500-ml glass flask containingair at a predetermined temperature. The contents of the flask1This test method is under the jurisdiction of ASTM Committee E27 on HazardPotential of Chemicals, and is

14、 the direct responsibility of Subcommittee E27.04 onFlammability and Ignitability of Liquid Chemicals.Current edition approved Sept. 15, 2005. Published December 2005. Originallyapproved in 1978. Last previous edition approved in 2000 as E 659 78 (2000).2For referenced ASTM standards, visit the ASTM

15、 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 Conshohocken, PA 19428-2959, United

16、 States.are observed in a dark room for 10 min following insertion ofthe sample, or until autoignition occurs. Autoignition is evi-denced by the sudden appearance of a flame inside the flaskand by a sharp rise in the temperature of the gas mixture. Thelowest internal flask temperature (T) at which h

17、ot-flameignition occurs for a series of prescribed sample volumes istaken to be the hot-flame autoignition temperature (AIT) of thechemical in air at atmospheric pressure. Ignition delay times(ignition time lags) are measured in order to determine theignition delay-ignition temperature relationship.

18、4.2 The temperatures at which cool-flame ignitions areobserved or evidenced by small sharp rises of the gas mixturetemperature are also recorded along with the correspondingignition delay times. The lowest flask temperature at whichcool-flame ignition occurs is taken to be the cool-flameautoignition

19、 temperature (CFT). Similarly, observations aremade of any nonluminous preflame reactions, as evidenced bya relatively gradual temperature rise which then falls off to thebase temperature. The lowest flask temperature at which thesereactions are observed is the reaction threshold temperature(RTT).NO

20、TE 3The hot-flame autoignition, cool-flame autoignition, and re-action threshold temperatures obtained by this test method approximatethose temperatures obtained by Test Method D 2883 for hot-flamereaction, cool-flame reaction, and reaction threshold, respectively.5. Significance and Use5.1 Autoigni

21、tion, by its very nature, is dependent on thechemical and physical properties of the material and themethod and apparatus employed for its determination. Theautoignition temperature by a given method does not necessar-ily represent the minimum temperature at which a givenmaterial will self-ignite in

22、 air. The volume of the vessel used isparticularly important since lower autoignition temperatureswill be achieved in larger vessels. (See Appendix X2.) Vesselmaterial can also be an important factor.5.2 The temperatures determined by this test method arethose at which air oxidation leads to ignitio

23、n. These tempera-tures can be expected to vary with the test pressure and oxygenconcentration.5.3 This test method is not designed for evaluating materialswhich are capable of exothermic decomposition. For suchmaterials, ignition is dependent upon the thermal and kineticproperties of the decompositi

24、on, the mass of the sample, andthe heat transfer characteristics of the system.5.4 This test method can be employed for solid chemicalswhich melt and vaporize or which readily sublime at the testtemperature. No condensed phase, liquid or solid, should bepresent when ignition occurs.5.5 This test met

25、hod is not designed to measure the autoi-gnition temperature of materials which are solids or liquids atthe test temperature (for example, wood, paper, cotton, plastics,and high-boiling point chemicals). Such materials will ther-mally degrade in the flask and the accumulated degradationproducts may

26、ignite.5.6 This test method was developed primarily for liquidchemicals but has been employed to test readily vaporizedsolids. Responsibility for extension of this method to solids ofunknown thermal stability, boiling point, or degradation char-acteristics rests with the operator.6. Apparatus6.1 Fur

27、naceAn electrically heated crucible furnace orfluidized sand bath of appropriate internal geometry anddimensions to contain the test flask and which will maintain auniform temperature within the flask shall be used. A furnacewith a cylindrically shaped interior, 5 in. (12.7 cm) in insidediameter, an

28、d 7 in. (17.8 cm) deep is minimal for this purpose.It should be capable of attaining a temperature of 600C orhigher.6.2 Temperature ControllerAtemperature control system,capable of controlling the temperature in the furnace towithin6 1C at temperatures up to 350C, and to within 62Cabove 350C, is req

29、uired. Temperatures are monitored at thebottom, side, and neck of the flask by means of three externalthermocouples. Heating adjustments are made when necessaryin order to maintain uniform temperature within the flask. If acontroller is not available, temperature control may beachieved by the use of

30、 suitable autotransformers or rheostats,thermocouples, and a suitable potentiometer.6.3 Test FlaskThe test flask shall be a commercial 500-mlborosilicate round-bottom, short-necked boiling flask.6.3.1 The flask is closely wrapped in reflective metal foil,such as aluminum, to promote temperature unif

31、ormity, and issuspended in the furnace so as to be completely enclosed withthe top of the neck being inset below the top of the insulatedcover (see Fig. 1).6.3.2 The flask is suspended in the furnace or sand bath bymeans of a thick insulating holder, the bottom of which is alsocovered with reflectiv

32、e metal foil.6.4 Hypodermic SyringeA 500 or 1000-l hypodermicsyringe equipped with a 6-in., No. 26 or finer stainless steelneedle, and calibrated in units of 10 l should be used to injectliquid samples into the heated flask. It is suggested that aneedle with a right-angle bend be used so that the op

33、eratorsfingers can be kept away from the flask opening.6.5 BalanceA laboratory balance capable of weighing tothe nearest 10 mg shall be used for preparing samples that aresolid at room temperature. Sample weights will range from 10to 1000 mg.6.6 Powder FunnelA 60-mm filling funnel is used to aidthe

34、insertion of solid samples into the flask. It is suggested thata holder such as a small buret clamp be used so that theoperators fingers can be kept away from the flask opening.6.7 ThermocoupleA fine Chromel-Alumel thermocouple(36 B and S gage) is used for measuring the gas temperature(T) inside the

35、 flask. Position the tip of the thermocouple at thecenter of the flask. Thermocouples should be calibrated againststandard temperatures or a standard thermocouple, and shouldbe rechecked frequently. Iron-constantan thermocouples are tobe avoided because they may promote catalytic oxidation onthe iro

36、n-oxide surface. External flask temperatures are mea-sured with a No. 20 B and S gage or finer thermocouplemounted at the top ( t1), middle (t2), and bottom (t3)oftheflask.6.8 Recording PotentiometerA fast response (1 s or lessfor full scale pen travel) variable range and variable chart speedE 659 7

37、8 (2005)2recording potentiometer shall be used for recording the signalfrom the internal gas thermocouple (T). An x - y recorder hasbeen found suitable for this purpose.6.9 TimerA stop watch or electric timer (preferably foot-switch operated) calibrated in 0.1 or 0.2-s units shall be used todetermin

38、e the time lag before ignition (time interval betweenthe instant of sample insertion and that of ignition as evidencedby the appearance of the flame). If visual ignition is difficult toobserve, the temperature - time recorder trace may be used toestimate the time lag.6.10 MirrorA 6-in. mirror or oth

39、er suitable size, mountedabove the flask so that the observer may see into the flaskwithout having to be directly over it.6.11 Hot-Air GunA suitable hot-air gun may be used topurge the product gases after a reaction is completed andbefore the next test. A temperature-controlled, hot-air guncanreduce

40、 testing time if used to aid in achieving the desired flashtemperature between trials and upon insertion of clean testflasks.7. Safety Considerations7.1 No explosion hazard is encountered in conducting thedetermination as outlined in Section 7. However, flames areoccasionally emitted well above the

41、top of the flask. Thus, theoperator should always use a mirror for observation of the flaskinterior. The use of a right-angle syringe and, for solids, the useof a holder for the powder funnel will remove the hands fromthe immediate vicinity of the flask opening.7.2 It is recommended that the apparat

42、us be installed in afume hood or be equipped with an exhaust duct to preventexposure to potentially toxic combustion and decompositionproducts. All tests with toxic chemicals should involve the useof adequate exhaust ventilation.7.3 Determinations normally should not be made on poten-tial or known e

43、xplosive or propellant materials. Where suchAIT information is required, the determinations should bemade remotely behind a barricade.8. Procedure8.1 Temperature ControlAfter the internal flask tempera-ture (T) has reached the desired temperature, adjust thetemperature controller to maintain this te

44、mperature within thedesignated limits and allow the system to equilibrate.8.2 LightingThe lighting before sample insertion shouldbe very subdued. Extinguish the lights as the sample isinserted. Cool-flame tests are generally conducted in totaldarkness. Eyes should be totally dark-adapted for optimum

45、observation of cool flames.8.3 Sample Addition:8.3.1 LiquidsInject 100 l of the sample to be tested intothe flask with the hypodermic syringe and quickly withdrawthe syringe. Extinguish the lights as the sample is injected.8.3.2 SolidsInsert a 100-mg sample by pouring it from theweighing vessel thro

46、ugh the powder funnel which is inserted inthe neck of the flask. Quickly withdraw the powder funnel andextinguish the lights.FIG. 1 Autoignition Temperature ApparatusE 659 78 (2005)38.4 Time MeasurementStart the timer as the sample isinserted into the flask, and also mark this on the recorder trace.

47、In most cases, the recorder trace of the interior thermocouplewill indicate the time of sample injection as a cooling spike.8.5 Observations and Subsequent Trials Observe theinside of the test flask in total darkness by means of the mirrorplaced at an appropriate angle above the flask.8.5.1 If ignit

48、ion is not observed in 10 min, consider theconcentration of the sample tested to be nonflammable at thegas temperature in the flask (Note 4). Completely purge theflask with the hot-air gun. Reset the timer and recorder. Repeatthe test at a higher temperature (about 30C). Allow time forattainment of

49、thermal equilibrium between trials. An elapsedtime of 10 min is sufficient. Shorter intervals may be employedfor preliminary trials. Thermal equilibrium should be ensuredfor final trials.NOTE 4Most materials ignite in less than 10 min. However, somechemicals (such as saturated cyclic organics) do exhibit long delay times.Initial tests may be conducted employing shorter delay times, but finaltrials should be based on a 10-min test time.8.5.2 If positive ignition occurs, stop the timer and recordthe time interval between sample insertion and ignit