ASTM E659-2014 5780 Standard Test Method for Autoignition Temperature of Liquid Chemicals《液体化学品自燃温度的标准试验方法》.pdf

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1、Designation: E659 14Standard Test Method forAutoignition Temperature of Liquid Chemicals1This standard is issued under the fixed designation E659; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number

2、in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method is one of several methods developed by ASTM Committee E27 for determiningthe hazards of chemicals. It is designed to be used

3、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.NOTE 1Within certain li

4、mitations, this test method can also be used todetermine the autoignition temperature of solid chemicals which readilymelt and vaporize at temperatures below the test temperature and forchemicals that are gaseous at atmospheric pressure and temperature.NOTE 2After a round robin study, Test Method D2

5、155 wasdiscontinued, and replaced by Test Method E659 in 1978. See alsoAppendix X2.1.2 This standard 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 app

6、raise 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 which takes into account allof the factors which are pertinent to an assessment of the firehazard of a particular end us

7、e.2. Referenced Documents2.1 ASTM Standards:2D2155 Test Method for Determination of Fire Resistance ofAircraft Hydraulic Fluids by Autoignition TemperatureD2883 Test Method for Reaction Threshold Temperature ofLiquid and Solid MaterialsE659 Test Method for Autoignition Temperature of LiquidChemicals

8、3. Terminology3.1 Definitions:3.1.1 ignition, nthe initiation of combustion.3.1.1.1 DiscussionIgnition, which is subjective, is definedfor this test method as the appearance of a flame accompaniedby a sharp rise in the temperature of the gas mixture. Thedetermination is made in total darkness becaus

9、e some flames,such as cool-flames, are observed with difficulty.3.1.2 autoignition, nthe ignition of a material commonlyin air as the result of heat liberation due to an exothermicoxidation reaction in the absence of an external ignition sourcesuch as a spark or flame.3.1.3 autoignition temperature,

10、 nthe minimum tempera-ture at which autoignition occurs under the specified conditionsof test.3.1.3.1 DiscussionAutoignition temperature is also re-ferred to as spontaneous ignition temperature, self-ignitiontemperature, autogenous ignition temperature, and by theacronymsAIT and SIT.As determined by

11、 this test method,AITis the lowest temperature at which the substance will producehot-flame ignition in air at atmospheric pressure without the aidof an external energy source such as spark or flame. It is thelowest temperature to which a combustible mixture must beraised, so that the rate of heat e

12、volved by the exothermicoxidation reaction will over-balance the rate at which heat islost to the surroundings and cause ignition.3.1.4 cool-flame, na faint, pale blue luminescence orflame occurring below the autoignition temperature (AIT).3.1.4.1 DiscussionCool-flames occur in rich vapor-airmixture

13、s of most hydrocarbons and oxygenated hydrocarbons.They are the first part of the multistage ignition process.3.1.5 ignition delay time, nthe time lapse between appli-cation of heat to a material and its ignition. It is the time inseconds between insertion of the sample into the flask andignition. I

14、t is maximum at the minimum autoignition tempera-ture and also referred to as ignition lag.1This test method is under the jurisdiction of ASTM Committee E27 on HazardPotential of Chemicals and is the direct responsibility of Subcommittee E27.04 onFlammability and Ignitability of Chemicals.Current ed

15、ition approved Feb. 1, 2014. Published February 2014. Originallyapproved in 1978. Last previous edition approved in 2013 as E659 13. DOI:10.1520/E0659-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS

16、tandards 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 States14. Summary of Test Method4.1 A small, metered sample of the product to be tested isinserted i

17、nto a uniformly heated 500-ml glass flask containingair at a predetermined temperature. The contents of the flaskare 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 b

18、y a sharp rise in the temperature of the gas mixture. Thelowest internal flask temperature (T) at which hot-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(ig

19、nition time lags) are measured in order to determine theignition delay-ignition temperature relationship.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.

20、The lowest flask temperature at whichcool-flame ignition occurs is taken to be the cool-flameautoignition 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 lo

21、west flask temperature at which thesereactions are observed is the reaction threshold temperature(RTT).NOTE 3The hot-flame autoignition, cool-flame autoignition, andreaction threshold temperatures obtained by this test method approximatethose temperatures obtained by Test Method D2883 for hot-flame

22、reaction,cool-flame reaction, and reaction threshold, respectively.5. Significance and Use5.1 Autoignition, 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 metho

23、d does not necessar-ily represent the minimum temperature at which a givenmaterial will self-ignite in 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 facto

24、r.5.2 The temperatures determined by this test method arethose at which air oxidation leads to ignition. 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 decompositi

25、on. For suchmaterials, ignition is dependent upon the thermal and kineticproperties of the decomposition, 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 testtem

26、perature. No condensed phase, liquid or solid, should bepresent when ignition occurs.5.5 This test method 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 chemic

27、als). Such materials will ther-mally degrade in the flask and the accumulated degradationproducts may ignite.5.6 This test method can be used, with appropriatemodifications, for chemicals that are gaseous at atmospherictemperature and pressure.5.7 This test method was developed primarily for liquidc

28、hemicals but has been employed to test readily vaporizedsolids. Responsibility for extension of this test method to solidsof unknown thermal stability, boiling point, or degradationcharacteristics rests with the operator.6. Apparatus6.1 FurnaceAn electrically heated crucible furnace orfluidized sand

29、 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, and 7 in. (17.8 cm) deep is minimal for this purpose.It should

30、 be capable of attaining a temperature of 600C orhigher.6.2 Temperature ControllerA temperature control system,capable of controlling the temperature in the furnace to within61C at temperatures up to 350C, and to within 62C above350C, is required. Temperatures are monitored at the bottom,side, and n

31、eck 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 suitable autotransformers or rheostats,thermocouples, and

32、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 uniformity, and issuspended in the furnace so as to be complete

33、ly 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 reflective metal foil.6.4 Hypodermic SyringeA 500 or 1000-l hypoderm

34、icsyringe 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 operatorsfingers can be kept away from the flask opening.6.5

35、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 insertion of solid samples into the flask. It is suggested

36、thata holder such as a small buret clamp be used so that theoperators fingers can be kept away from the flask opening.E659 1426.7 ThermocoupleA fine Chromel-Alumel thermocouple(36 B and S gage) is used for measuring the gas temperature(T) inside the flask. Position the tip of the thermocouple at the

37、center 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 iron-oxide surface. External flask temperatures are me

38、a-sured with a No. 20 B and S gage or finer thermocouplemounted at the top (t1), middle (t2), and bottom (t3) of the flask.6.8 Recording PotentiometerA fast response (1 s or lessfor full scale pen travel) variable range and variable chart speedrecording potentiometer shall be used for recording the

39、signalfrom the internal gas thermocouple (T). An XY 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 todetermine the time lag before ignition (time interval betweenthe instant of

40、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 other suitable size, mountedabove the flask so that the observer may see

41、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 testing time if used to aid in achieving the desired flashtemperature

42、 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 top of the flask. Thus, theoperator should always use a mirror for obs

43、ervation 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 apparatus be installed in afume hood or be equipped with an exhaust duct to p

44、reventexposure 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 explosive or propellant materials. Where suchAIT information is require

45、d, the determinations should bemade remotely behind a barricade.FIG. 1 Autoignition Temperature ApparatusE659 1438. Procedure8.1 Temperature ControlAfter the internal flask tempera-ture (T) has reached the desired temperature, adjust thetemperature controller to maintain this temperature within thed

46、esignated 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 optimumobservation of cool f

47、lames.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 through the powder funnel

48、 which is inserted inthe neck of the flask. Quickly withdraw the powder funnel andextinguish the lights.8.3.3 GasesInject 100 mg of the sample to be tested intothe flask with a syringe (or other means such as one describedin Appendix X4) and quickly withdraw the syringe. Extinguishthe lights as the

49、sample is injected.NOTE 4Ideal gas law, with the average molecular weight of theinjected gas, may be used to determine the necessary volume of the testgas to be drawn into the syringe.NOTE 5For low molecular weight gases, it may be more appropriateto select the initial test gas volume to be drawn into the syringe from thestoichiometric concentration or from (LFL+UFL)/2. In that case, thesearch approach provided in 8.5.3 will need to be modified accordingly.NOTE 6Low molecular weight gases require addition of large vol-umes that are apprecia