ASTM E659-15(2023)
(Test Method)Standard Test Method for Autoignition Temperature of Chemicals
Standard Test Method for Autoignition Temperature of Chemicals
SIGNIFICANCE AND USE
5.1 Autoignition, by its very nature, is dependent on the chemical and physical properties of the material and the method and apparatus employed for its determination. The autoignition temperature by a given method does not necessarily represent the minimum temperature at which a given material will self-ignite in air. The volume of the vessel used is particularly important since lower autoignition temperatures will be achieved in larger vessels. (See Appendix X2.) Vessel material can also be an important factor.
5.2 The temperatures determined by this test method are those at which air oxidation leads to ignition. These temperatures can be expected to vary with the test pressure and oxygen concentration.
5.3 This test method is not designed for evaluating materials which are capable of exothermic decomposition. For such materials, ignition is dependent upon the thermal and kinetic properties of the decomposition, the mass of the sample, and the heat transfer characteristics of the system.
5.4 This test method can be employed for solid chemicals which melt and vaporize or which readily sublime at the test temperature. No condensed phase, liquid or solid, should be present when ignition occurs.
5.5 This test method is not designed to measure the autoignition temperature of materials which are solids or liquids at the test temperature (for example, wood, paper, cotton, plastics, and high-boiling point chemicals). Such materials will thermally degrade in the flask and the accumulated degradation products may ignite.
5.6 This test method can be used, with appropriate modifications, for chemicals that are gaseous at atmospheric temperature and pressure.
5.7 This test method was developed primarily for liquid chemicals but has been employed to test readily vaporized solids. Responsibility for extension of this test method to solids of unknown thermal stability, boiling point, or degradation characteristics rests with the operator.
SCOPE
1.1 This test method covers the determination of hot- and cool-flame autoignition temperatures of a liquid chemical in air at atmospheric pressure in a uniformly heated vessel.
Note 1: Within certain limitations, this test method can also be used to determine the autoignition temperature of solid chemicals which readily melt and vaporize at temperatures below the test temperature and for chemicals that are gaseous at atmospheric pressure and temperature.
Note 2: After a round robin study, Test Method D2155 was discontinued, and replaced by Test Method E659 in 1978. See also Appendix X2.
1.2 This standard should be used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. However, results of this test may be used as elements of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular end use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E659 − 15 (Reapproved 2023)
Standard Test Method for
Autoignition Temperature of Chemicals
This standard is issued under the fixed designation E659; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This test method is one of several methods developed by ASTM Committee E27 for determining
the hazards of chemicals. It is designed to be used in conjunction with other tests to characterize the
hazard potential of the chemical under test.
1. Scope D2155 Test Method for Determination of Fire Resistance of
Aircraft Hydraulic Fluids by Autoignition Temperature
1.1 This test method covers the determination of hot- and
D2883 Test Method for Reaction Threshold Temperature of
cool-flame autoignition temperatures of a liquid chemical in air
Liquid and Solid Materials (Withdrawn 2016)
at atmospheric pressure in a uniformly heated vessel.
E659 Test Method for Autoignition Temperature of Chemi-
NOTE 1—Within certain limitations, this test method can also be used to
cals
determine the autoignition temperature of solid chemicals which readily
melt and vaporize at temperatures below the test temperature and for
3. Terminology
chemicals that are gaseous at atmospheric pressure and temperature.
NOTE 2—After a round robin study, Test Method D2155 was
3.1 Definitions:
discontinued, and replaced by Test Method E659 in 1978. See also
3.1.1 ignition, n—the initiation of combustion.
Appendix X2.
3.1.1.1 Discussion—Ignition, which is subjective, is defined
1.2 This standard should be used to measure and describe
for this test method as the appearance of a flame accompanied
the properties of materials, products, or assemblies in response
by a sharp rise in the temperature of the gas mixture. The
to heat and flame under controlled laboratory conditions and
determination is made in total darkness because some flames,
should not be used to describe or appraise the fire hazard or
such as cool-flames, are observed with difficulty.
fire risk of materials, products, or assemblies under actual fire
3.1.2 autoignition, n—the ignition of a material commonly
conditions. However, results of this test may be used as
in air as the result of heat liberation due to an exothermic
elements of a fire risk assessment which takes into account all
oxidation reaction in the absence of an external ignition source
of the factors which are pertinent to an assessment of the fire
such as a spark or flame.
hazard of a particular end use.
3.1.3 autoignition temperature, n—the minimum tempera-
1.3 This international standard was developed in accor-
ture at which autoignition occurs under the specified conditions
dance with internationally recognized principles on standard-
of test.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1.3.1 Discussion—Autoignition temperature is also re-
mendations issued by the World Trade Organization Technical
ferred to as spontaneous ignition temperature, self-ignition
Barriers to Trade (TBT) Committee.
temperature, autogenous ignition temperature, and by the
acronyms AIT and SIT. As determined by this test method, AIT
2. Referenced Documents
is the lowest temperature at which the substance will produce
2.1 ASTM Standards:
hot-flame ignition in air at atmospheric pressure without the aid
of an external energy source such as spark or flame. It is the
This test method is under the jurisdiction of ASTM Committee E27 on Hazard
lowest temperature to which a combustible mixture must be
Potential of Chemicals and is the direct responsibility of Subcommittee E27.04 on
raised, so that the rate of heat evolved by the exothermic
Flammability and Ignitability of Chemicals.
oxidation reaction will over-balance the rate at which heat is
Current edition approved May 1, 2023. Published May 2023. Originally
lost to the surroundings and cause ignition.
approved in 1978. Last previous edition approved in 2015 as E659 – 15. DOI:
10.1520/E0659-15R23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E659 − 15 (2023)
3.1.4 cool-flame, n—a faint, pale blue luminescence or materials, ignition is dependent upon the thermal and kinetic
flame occurring below the autoignition temperature (AIT). properties of the decomposition, the mass of the sample, and
the heat transfer characteristics of the system.
3.1.4.1 Discussion—Cool-flames occur in rich vapor-air
5.4 This test method can be employed for solid chemicals
mixtures of most hydrocarbons and oxygenated hydrocarbons.
which melt and vaporize or which readily sublime at the test
They are the first part of the multistage ignition process.
temperature. No condensed phase, liquid or solid, should be
3.1.5 ignition delay time, n—the time lapse between appli-
present when ignition occurs.
cation of heat to a material and its ignition. It is the time in
seconds between insertion of the sample into the flask and
5.5 This test method is not designed to measure the autoi-
ignition. It is maximum at the minimum autoignition tempera-
gnition temperature of materials which are solids or liquids at
ture and also referred to as ignition lag.
the test temperature (for example, wood, paper, cotton, plastics,
and high-boiling point chemicals). Such materials will ther-
4. Summary of Test Method
mally degrade in the flask and the accumulated degradation
4.1 A small, metered sample of the product to be tested is
products may ignite.
inserted into a uniformly heated 500 mL glass flask containing
5.6 This test method can be used, with appropriate
air at a predetermined temperature. The contents of the flask
modifications, for chemicals that are gaseous at atmospheric
are observed in a dark room for 10 min following insertion of
temperature and pressure.
the sample, or until autoignition occurs. Autoignition is evi-
denced by the sudden appearance of a flame inside the flask 5.7 This test method was developed primarily for liquid
and by a sharp rise in the temperature of the gas mixture. The
chemicals but has been employed to test readily vaporized
lowest internal flask temperature (T) at which hot-flame solids. Responsibility for extension of this test method to solids
ignition occurs for a series of prescribed sample volumes is
of unknown thermal stability, boiling point, or degradation
taken to be the hot-flame autoignition temperature (AIT) of the characteristics rests with the operator.
chemical in air at atmospheric pressure. Ignition delay times
(ignition time lags) are measured in order to determine the
6. Apparatus
ignition delay-ignition temperature relationship.
6.1 Furnace—An electrically heated crucible furnace or
4.2 The temperatures at which cool-flame ignitions are
fluidized sand bath of appropriate internal geometry and
observed or evidenced by small sharp rises of the gas mixture
dimensions to contain the test flask and which will maintain a
temperature are also recorded along with the corresponding
uniform temperature within the flask shall be used. A furnace
ignition delay times. The lowest flask temperature at which
with a cylindrically shaped interior, 5 in. (12.7 cm) in inside
cool-flame ignition occurs is taken to be the cool-flame
diameter, and 7 in. (17.8 cm) deep is minimal for this purpose.
autoignition temperature (CFT). Similarly, observations are
It should be capable of attaining a temperature of 600 °C or
made of any nonluminous preflame reactions, as evidenced by
higher.
a relatively gradual temperature rise which then falls off to the
6.2 Temperature Controller—A temperature control system,
base temperature. The lowest flask temperature at which these
capable of controlling the temperature in the furnace to within
reactions are observed is the reaction threshold temperature
61 °C at temperatures up to 350 °C, and to within 62 °C
(RTT).
above 350 °C, is required. Temperatures are monitored at the
NOTE 3—The hot-flame autoignition, cool-flame autoignition, and
bottom, side, and neck of the flask by means of three external
reaction threshold temperatures obtained by this test method approximate
thermocouples. Heating adjustments are made when necessary
those temperatures obtained by Test Method D2883 for hot-flame reaction,
in order to maintain uniform temperature within the flask. If a
cool-flame reaction, and reaction threshold, respectively.
controller is not available, temperature control may be
achieved by the use of suitable autotransformers or rheostats,
5. Significance and Use
thermocouples, and a suitable potentiometer.
5.1 Autoignition, by its very nature, is dependent on the
chemical and physical properties of the material and the 6.3 Test Flask—The test flask shall be a commercial 500 mL
method and apparatus employed for its determination. The
borosilicate round-bottom, short-necked boiling flask.
autoignition temperature by a given method does not necessar-
6.3.1 The flask is closely wrapped in reflective metal foil,
ily represent the minimum temperature at which a given
such as aluminum, to promote temperature uniformity, and is
material will self-ignite in air. The volume of the vessel used is
suspended in the furnace so as to be completely enclosed with
particularly important since lower autoignition temperatures
the top of the neck being inset below the top of the insulated
will be achieved in larger vessels. (See Appendix X2.) Vessel
cover (see Fig. 1).
material can also be an important factor.
6.3.2 The flask is suspended in the furnace or sand bath by
means of a thick insulating holder, the bottom of which is also
5.2 The temperatures determined by this test method are
covered with reflective metal foil.
those at which air oxidation leads to ignition. These tempera-
tures can be expected to vary with the test pressure and oxygen
6.4 Hypodermic Syringe—A 500 μL or 1000 μL hypodermic
concentration.
syringe equipped with a 6 in., No. 26 or finer stainless steel
5.3 This test method is not designed for evaluating materials needle, and calibrated in units of 10 μL should be used to inject
which are capable of exothermic decomposition. For such liquid samples into the heated flask. It is suggested that a
E659 − 15 (2023)
FIG. 1 Autoignition Temperature Apparatus
needle with a right-angle bend be used so that the operator’s 6.9 Timer—A stop watch or electric timer (preferably foot-
fingers can be kept away from the flask opening. switch operated) calibrated in 0.1 s or 0.2 s units shall be used
to determine the time lag before ignition (time interval between
6.5 Balance—A laboratory balance capable of weighing to
the instant of sample insertion and that of ignition as evidenced
the nearest 10 mg shall be used for preparing samples that are
by the appearance of the flame). If visual ignition is difficult to
solid at room temperature. Sample weights will range from
observe, the temperature-time recorder trace may be used to
10 mg to 1000 mg.
estimate the time lag.
6.6 Powder Funnel—A 60 mm filling funnel is used to aid
6.10 Mirror—A 6 in. mirror or other suitable size, mounted
the insertion of solid samples into the flask. It is suggested that
above the flask so that the observer may see into the flask
a holder such as a small buret clamp be used so that the
without having to be directly over it.
operator’s fingers can be kept away from the flask opening.
6.11 Hot-Air Gun—A suitable hot-air gun may be used to
6.7 Thermocouple—A fine Chromel-Alumel thermocouple
purge the product gases after a reaction is completed and
(36 B and S gauge) is used for measuring the gas temperature
before the next test. A temperature-controlled, hot-air guncan
(T) inside the flask. Position the tip of the thermocouple at the
reduce testing time if used to aid in achieving the desired flash
center of the flask. Thermocouples should be calibrated against
temperature between trials and upon insertion of clean test
standard temperatures or a standard thermocouple, and should
flasks.
be rechecked frequently. Iron-constantan thermocouples are to
be avoided because they may promote catalytic oxidation on
7. Safety Considerations
the iron-oxide surface. External flask temperatures are mea-
sured with a No. 20 B and S gauge or finer thermocouple
7.1 No explosion hazard is encountered in conducting the
mounted at the top (t ), middle (t ), and bottom (t ) of the flask.
1 2 3
determination as outlined in Section 7. However, flames are
6.8 Recording Potentiometer—A fast response (1 s or less occasionally emitted well above the top of the flask. Thus, the
for full scale pen travel) variable range and variable chart speed operator should always use a mirror for observation of the flask
recording potentiometer shall be used for recording the signal interior. The use of a right-angle syringe and, for solids, the use
from the internal gas thermocouple (T). An X–Y recorder has of a holder for the powder funnel will remove the hands from
been found suitable for this purpose. the immediate vicinity of the flask opening.
E659 − 15 (2023)
7.2 It is recommended that the apparatus be installed in a time of 10 min is sufficient. Shorter intervals may be employed
fume hood or be equipped with an exhaust duct to prevent for preliminary trials. Thermal equilibrium should be ensured
exposure to potentially toxic combustion and decomposition for final trials.
products. All tests with toxic chemicals should involve the use
NOTE 7—Most materials ignite in less than 10 min. However, some
of adequate exhaust ventilation.
chemicals (such as saturated cyclic organics) do exhibit long delay times.
Initial tests may be conducted employing shorter delay times, but final
7.3 Determinations normally should not be made on poten-
trials should be based on a 10 min test time.
tial or known explosive or propellant materials. Where such
8.5.2 If positive ignition occurs, stop the timer and record
AIT information is required, the determinations should be
the time interval between sample insertion and igniti
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