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ASTM E1231-10

(Practice)

Standard Practice for Calculation of Hazard Potential Figures-of-Merit for Thermally Unstable Materials

Standard Practice for Calculation of Hazard Potential Figures-of-Merit for Thermally Unstable Materials

SIGNIFICANCE AND USE
This practice provides nine figures-of-merit which may be used to estimate the relative thermal hazard potential of thermally unstable materials. Since numerous assumptions must be made in order to obtain these figures-of-merit, care must be exercised to avoid too rigorous interpretation (or even misapplication) of the results.
This practice may be used for comparative purposes, specification acceptance, and research. It should not be used to predict actual performance.
SCOPE
1.1 This practice covers the calculation of hazard potential figures-of-merit for exothermic reactions, including:
(1) Time-to-thermal-runaway,
(2) Time-to-maximum-rate,
(3) Critical half thickness,
(4) Critical temperature,
(5) Adiabatic decomposition temperature rise,
(6) Explosion potential,
(7) Shock sensitivity,
(8) Instantaneous power density, and
(9) NFPA instability rating.
1.2 The kinetic parameters needed in this calculation may be obtained from differential scanning calorimetry (DSC) curves by methods described in other documents.
1.3 This technique is the best applicable to simple, single reactions whose behavior can be described by the Arrhenius equation and the general rate law. For reactions which do not meet these conditions, this technique may, with caution, serve as an approximation.
1.4 The calculations and results of this practice might be used to estimate the relative degree of hazard for experimental and research quantities of thermally unstable materials for which little experience and few data are available. Comparable calculations and results performed with data developed for well characterized materials in identical equipment, environment, and geometry are key to the ability to estimate relative hazard.
1.5 The figures-of-merit calculated as described in this practice are intended to be used only as a guide for the estimation of the relative thermal hazard potential of a system (materials, container, and surroundings). They are not intended to predict actual thermokinetic performance. The calculated errors for these parameters are an intimate part of this practice and must be provided to stress this. It is strongly recommended that those using the data provided by this practice seek the consultation of qualified personnel for proper interpretation.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 There is no ISO standard equivalent to this practice.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
14-Apr-2010
ICS
13.230 - Explosion protection
Technical Committee
E27 - Hazard Potential of Chemicals
Drafting Committee
E27.02 - Thermal Stability and Condensed Phases
Current Stage
Ref Project

Relations

Replaces
ASTM E1231-01(2006) - Standard Practice for Calculation of Hazard Potential Figures-of-Merit for Thermally Unstable Materials
Effective Date
15-Apr-2010
Replaced By
ASTM E1231-15 - Standard Practice for Calculation of Hazard Potential Figures of Merit for Thermally Unstable Materials
Effective Date
01-Nov-2015
Referred By
ASTM E2012-06(2020) - Standard Guide for the Preparation of a Binary Chemical Compatibility Chart
Effective Date
15-Apr-2010
Referred By
ASTM E1445-08(2015) - Standard Terminology Relating to Hazard Potential of Chemicals
Effective Date
15-Apr-2010
Referred By
ASTM E2160-04(2018) - Standard Test Method for Heat of Reaction of Thermally Reactive Materials by Differential Scanning Calorimetry
Effective Date
15-Apr-2010
Referred By
ASTM E2890-21 - Standard Test Method for Determination of Kinetic Parameters and Reaction Order for Thermally Unstable Materials by Differential Scanning Calorimetry Using the Kissinger and Farjas Methods
Effective Date
15-Apr-2010
Referred By
ASTM E1952-23 - Standard Test Method for Thermal Conductivity and Thermal Diffusivity by Modulated Temperature Differential Scanning Calorimetry
Effective Date
15-Apr-2010
Referred By
ASTM E1981-22 - Standard Guide for Assessing Thermal Stability of Materials by Methods of Accelerating Rate Calorimetry
Effective Date
15-Apr-2010
Referred By
ASTM E698-23 - Standard Test Method for Kinetic Parameters for Thermally Unstable Materials Using Differential Scanning Calorimetry and the Flynn/Wall/Ozawa Method
Effective Date
15-Apr-2010

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ASTM E1231-10 - Standard Practice for Calculation of Hazard Potential Figures-of-Merit for Thermally Unstable MaterialsASTM E1231-10 - Standard Practice for Calculation of Hazard Potential Figures-of-Merit for Thermally Unstable Materials
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Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1231 − 10
StandardPractice for
Calculation of Hazard Potential Figures-of-Merit for
1
Thermally Unstable Materials
This standard is issued under the fixed designation E1231; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope that those using the data provided by this practice seek the
consultation of qualified personnel for proper interpretation.
1.1 This practice covers the calculation of hazard potential
figures-of-merit for exothermic reactions, including: 1.6 The values stated in SI units are to be regarded as
(1)Time-to-thermal-runaway, standard. No other units of measurement are included in this
(2)Time-to-maximum-rate, standard.
(3)Critical half thickness,
1.7 There is no ISO standard equivalent to this practice.
(4)Critical temperature,
1.8 This standard does not purport to address all of the
(5)Adiabatic decomposition temperature rise,
safety concerns, if any, associated with its use. It is the
(6)Explosion potential,
responsibility of the user of this standard to establish appro-
(7)Shock sensitivity,
priate safety and health practices and determine the applica-
(8)Instantaneous power density, and
bility of regulatory limitations prior to use.
(9)NFPA instability rating.
1.2 The kinetic parameters needed in this calculation may
2. Referenced Documents
be obtained from differential scanning calorimetry (DSC)
2
2.1 ASTM Standards:
curves by methods described in other documents.
C177Test Method for Steady-State Heat Flux Measure-
1.3 This technique is the best applicable to simple, single
ments and Thermal Transmission Properties by Means of
reactions whose behavior can be described by the Arrhenius
the Guarded-Hot-Plate Apparatus
equation and the general rate law. For reactions which do not
C518Test Method for Steady-State Thermal Transmission
meet these conditions, this technique may, with caution, serve
Properties by Means of the Heat Flow Meter Apparatus
as an approximation.
E473Terminology Relating to Thermal Analysis and Rhe-
ology
1.4 The calculations and results of this practice might be
E537Test Method for The Thermal Stability of Chemicals
used to estimate the relative degree of hazard for experimental
by Differential Scanning Calorimetry
and research quantities of thermally unstable materials for
E698Test Method for Arrhenius Kinetic Constants for
whichlittleexperienceandfewdataareavailable.Comparable
Thermally Unstable Materials Using Differential Scan-
calculationsandresultsperformedwithdatadevelopedforwell
ning Calorimetry and the Flynn/Wall/Ozawa Method
characterized materials in identical equipment, environment,
E793Test Method for Enthalpies of Fusion and Crystalliza-
and geometry are key to the ability to estimate relative hazard.
tion by Differential Scanning Calorimetry
1.5 The figures-of-merit calculated as described in this
E1269Test Method for Determining Specific Heat Capacity
practice are intended to be used only as a guide for the
by Differential Scanning Calorimetry
estimation of the relative thermal hazard potential of a system
E1952Test Method for Thermal Conductivity and Thermal
(materials,container,andsurroundings).Theyarenotintended
Diffusivity by Modulated Temperature Differential Scan-
to predict actual thermokinetic performance. The calculated
ning Calorimetry
errors for these parameters are an intimate part of this practice
E2041Test Method for Estimating Kinetic Parameters by
andmustbeprovidedtostressthis.Itisstronglyrecommended
Differential Scanning Calorimeter Using the Borchardt
and Daniels Method
1
This practice is under the jurisdiction of ASTM Committee E27 on Hazard
Potential of Chemicals and is the direct responsibility of Subcommittee E27.02 on
2
Thermal Stability and Condensed Phases. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 15, 2010. Published May 2010. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1988. Last previous edition approved in 2006 as E1231–01 (2006). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/E1231-10. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E1231 − 10
E2070Test Method for Kinetic Parameters by Differential greater sensitivity; a negative value less sensitivity. The reli-
Scanning Calorimetry Using Isothermal Methods abilityofthisgo-no-goindicationisprovidedbythemagnitude
2.2 Other Standards: of the numerical
...

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E1231–01(Reapproved2006) Designation:E1231–10
Standard Practice for
Calculation of Hazard Potential Figures-of-Merit for
1
Thermally Unstable Materials
This standard is issued under the fixed designation E1231; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers the calculation of hazard potential figures-of-merit for exothermic reactions, including:
(1) Time-to-thermal-runaway,
(2) Critical half thickness, Time-to-maximum-rate,
(3) Critical temperature, Critical half thickness,
(4) Adiabatic decomposition temperature rise Critical temperature,
(5) Explosion potential, Adiabatic decomposition temperature rise,
(6) Shock sensitivity, Explosion potential,
(7) Instantaneous power density, and Shock sensitivity,
(8) Instantaneous power density, and
(9) NFPA instability rating.
1.2 The kinetic parameters needed in this calculation may be obtained from differential scanning calorimetry (DSC) curves by
methods described in other documents.
1.3 This technique is the best applicable to simple, single reactions whose behavior can be described by theArrhenius equation
and the general rate law. For reactions which do not meet these conditions, this technique may, with caution, serve as an
approximation.
1.4 The calculations and results of this practice might be used to estimate the relative degree of hazard for experimental and
research quantities of thermally unstable materials for which little experience and few data are available. Comparable calculations
andresultsperformedwithdatadevelopedforwellcharacterizedmaterialsinidenticalequipment,environment,andgeometryare
key to the ability to estimate relative hazard.
1.5 The figures-of-merit calculated as described in this practice are intended to be used only as a guide for the estimation of
the relative thermal hazard potential of a system (materials, container, and surroundings). They are not intended to predict actual
thermokinetic performance. The calculated errors for these parameters are an intimate part of this practice and must be provided
to stress this. It is strongly recommended that those using the data provided by this practice seek the consultation of qualified
personnel for proper interpretation.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 There is no ISO standard equivalent to this practice.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards: D4351Test Method for Measuring the Thermal Conductivity of Plastics By the Evaporation-Calorimetric
Method
C177 Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the
Guarded-Hot-Plate Apparatus
C518 Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus
1
This practice is under the jurisdiction ofASTM Committee E27 on Hazard Potential of Chemicals and is the direct responsibility of Subcommittee E27.02 on Thermal
Stability and Condensed Phases.
e1
Current edition approved April 1, 2006. Published May 2006. Originally approved in 1988. Last previous edition approved in 2001 as E1231–01 . DOI:
10.1520/E1231-01R06.
Current edition approved April 15, 2010. Published May 2010. Originally approved in 1988. Last previous edition approved in 2006 as E1231–01 (2006). DOI:
10.1520/E1231-10.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
E1231–10
E473 Terminology Relating to Thermal Analysis and Rheology
E537 Test Method for The Thermal Stability of Chemicals by Differential Scanning Calorimetry
E698 Test Method forArrhenius Kinetic Constants for Thermally Unstable Materials Using Differential Scanning
...

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Standard Test Method for Hot-Surface Ignition Temperature of Dust Layers

SIGNIFICANCE AND USE
5.1 This test method is applicable to dusts and powders, and provides a procedure for performing laboratory tests to evaluate hot-surface ignition temperatures of dust layers.  
5.2 The test data can be of value in determining safe operating conditions in industrial plants, mines, manufacturing processes, and locations of material usage and storage.  
5.3 Due to variation of ignition temperature with layer thickness, the test data at one thickness may not be applicable to all industrial situations (see Appendix X1). Tests at various layer thicknesses may provide a means for extrapolation to thicker layers, as listed in the following for pulverized Pittsburgh bituminous coal dust (2). Mathematical modeling of layer ignition at various layer thicknesses is described in Ref. (3).
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Note 1: Much of the literature data for layer ignition is actually from a basket in a heated furnace (4), known as the modified Godbert-Greenwald furnace test. Other data are from nonstandardized hot plates (5-9).  
5.6 Additional information on the significance and use of this test method may be found in Ref. (10).
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1.1 This test method covers a laboratory procedure to determine the hot-surface ignition temperature of dust layers, that is, measuring the minimum temperature at which a dust layer will self-heat. The test consists of a dust layer heated on a hot plate.2,3  
1.2 Data obtained from this test method provide a relative measure of the hot-surface ignition temperature of a dust layer.  
1.3 This test method should be used to measure and describe the properties of materials in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire hazard risk of materials, products, or assemblies under actual fire conditions. However, results of this test method may be used as elements of a fire risk assessment that takes into account all of the factors that are pertinent to an assessment of the fire hazard risk of a particular end use product.  
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ASTM E1515-14(2022)(Test Method)
Standard Test Method for Minimum Explosible Concentration of Combustible Dusts

SIGNIFICANCE AND USE
5.1 This test method provides a procedure for performing laboratory tests to evaluate relative deflagration parameters of dusts.  
5.2 The MEC as measured by this test method provides a relative measure of the concentration of a dust cloud necessary for an explosion.  
5.3 Since the MEC as measured by this test method may vary with the uniformity of the dust dispersion, energy of the ignitor, and propagation criteria, the MEC should be considered a relative rather than absolute measurement.  
5.4 If too weak an ignition source is used, the measured MEC would be higher than the “true” value. This is an ignitability limit rather than a flammability limit, and the test could be described as “underdriven.” Ideally, the ignition energy is increased until the measured MEC is independent of ignition energy. However, at some point the ignition energy may become too strong for the size of the test chamber, and the system becomes “overdriven.” When the ignitor flame becomes too large relative to the chamber volume, a test could appear to result in an explosion, while it is actually just dust burning in the ignitor flame with no real propagation beyond the ignitor.  
5.5 The recommended ignition source for measuring the MEC of dusts in 20-L chambers is a 2500 or 5000 J pyrotechnic ignitor.4 Measuring the MEC at both ignition energies will provide information on the possible overdriving of the system.5 To evaluate the effect of possible overdriving in a 20-L chamber, comparison tests may also be made in a larger chamber, such as a 1 m3-chamber.  
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ASTM E1226-19(Test Method)
Standard Test Method for Explosibility of Dust Clouds

SIGNIFICANCE AND USE
5.1 This test method provides a procedure for performing laboratory tests to evaluate deflagration parameters of dusts.  
5.2 The data developed by this test method may be used for the purpose of sizing deflagration vents in conjunction with the nomographs and equations published in NFPA 68, ISO 6184/1, or VDI 3673.  
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1.2 Limitations. Results obtained by the application of the methods of this standard pertain only to certain combustion characteristics of dispersed dust clouds. No inference should be drawn from such results relating to the combustion characteristics of dusts in other forms or conditions (for example, ignition temperature or spark ignition energy of dust clouds, ignition properties of dust layers on hot surfaces, ignition of bulk dust in heated environments, etc.)  
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ASTM E1231-19(Practice)
Standard Practice for Calculation of Hazard Potential Figures of Merit for Thermally Unstable Materials

SIGNIFICANCE AND USE
5.1 This practice provides nine figures of merit which may be used to estimate the relative thermal hazard of thermally unstable materials. Since numerous assumptions must be made in order to obtain these figures of merit, care must be exercised to avoid too rigorous interpretation (or even misapplication) of the results.  
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1.1 This practice covers the calculation of hazard potential figures of merit for exothermic reactions, including:
(1) Time-to-thermal-runaway,
(2) Time-to-maximum-rate,
(3) Critical half thickness,
(4) Critical temperature,
(5) Adiabatic decomposition temperature rise,
(6) Explosion potential,
(7) Shock sensitivity,
(8) Instantaneous power density, and
(9) National Fire Protection Association (NFPA) instability rating.  
1.2 The kinetic parameters needed in this calculation may be obtained from differential scanning calorimetry (DSC) curves by methods described in other documents.  
1.3 This technique is the best applicable to simple, single reactions whose behavior can be described by the Arrhenius equation and the general rate law. For reactions which do not meet these conditions, this technique may, with caution, serve as an approximation.  
1.4 The calculations and results of this practice might be used to estimate the relative degree of hazard for experimental and research quantities of thermally unstable materials for which little experience and few data are available. Comparable calculations and results performed with data developed for well characterized materials in identical equipment, environment, and geometry are key to the ability to estimate relative hazard.  
1.5 The figures of merit calculated as described in this practice are intended to be used only as a guide for the estimation of the relative thermal hazard potential of a system (materials, container, and surroundings). They are not intended to predict actual thermokinetic performance. The calculated errors for these parameters are an intimate part of this practice and must be provided to stress this. It is strongly recommended that those using the data provided by this practice seek the consultation of qualified personnel for proper interpretation.  
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.8 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.

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ASTM E2931-13(2019)(Test Method)
Standard Test Method for Limiting Oxygen (Oxidant) Concentration of Combustible Dust Clouds

SIGNIFICANCE AND USE
5.1 This test method provides a procedure for performing laboratory tests to evaluate relative deflagration parameters of dusts.  
5.2 Knowledge of the limiting oxygen (oxidant) concentration is needed for safe operation of some chemical processes. This information may be needed in order to start up, shut down or operate a process while avoiding the creation of flammable dust-gas atmospheres therein, or to pneumatically transport materials safely. NFPA 69 provides guidance for the practical use of LOC data, including the appropriate safety margin to use.  
5.3 Since the LOC as measured by this method may vary with the energy of the ignitor and the propagation criteria, the LOC should be considered a relative rather than absolute measurement.  
5.4 If too weak an ignition source is used, the measured LOC would be higher than the “true” value and would not be sufficiently conservative. This is an ignitability limit rather than a flammability limit, and the test could be described as “underdriven.” Ideally, the ignition energy is increased until the measured LOC is independent of ignition energy (that is, the “true” value). However, at some point the ignition energy may become too strong for the size of the test chamber, and the system becomes “overdriven.” When the ignitor flame becomes too large relative to the chamber volume, a test could appear to result in an explosion, while it is actually just dust burning in the ignitor flame with no real propagation beyond the ignitor (1-3).5 This LOC value would be overly conservative.  
5.5 The recommended ignition source for measuring the LOC of dusts in 20-L chambers is a 2500-J pyrotechnic ignitor.6 This ignitor contains 0.6 g of a powder mixture of 40 % zirconium, 30 % barium nitrate, and 30 % barium peroxide. Measuring the LOC at several ignition energies will provide information on the possible overdriving of the system to evaluate the effect of possible overdriving in a 20-L chamber, comparison tests may also be m...
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1.1 This test method is designed to determine the limiting oxygen concentration of a combustible dust dispersed in a mixture of air with an inert/nonflammable gas in a near-spherical closed vessel of 20 L or greater volume.  
1.2 Data obtained from this method provide a relative measure of the deflagration characteristics of dust clouds.  
1.3 This test method should be used to measure and describe the properties of materials 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 that takes into account all of the factors that are pertinent to an assessment of the fire hazard of a particular end use.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.  
1.6 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.

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ASTM E2019-03(2019)(Test Method)
Standard Test Method for Minimum Ignition Energy of a Dust Cloud in Air

SIGNIFICANCE AND USE
5.1 This test method provides a procedure for performing laboratory tests to determine the minimum ignition energy of a dust cloud.
Note 1: For gases and vapors, see Test Method E582.  
5.2 The data developed by this test method may be used to assess the spark ignitibility of a dust cloud. Additional guidance on the significance of minimum ignition energy is in X1.1.  
5.3 The values obtained are specific to the sample tested, the method used and the test equipment used. The values are not to be considered intrinsic material constants.  
5.4 The MIE of a dust as determined using this procedure can be compared with the MIE's of reference dusts (using the same procedure) to obtain the relative sensitivity of the dust to spark ignition. An understanding of the relative sensitivity to spark ignition can be used to minimize the probability of explosions due to spark ignition.
SCOPE
1.1 This test method determines the minimum ignition energy of a dust cloud in air by a high voltage spark.  
1.2 The minimum ignition energy (MIE) of a dust-cloud is primarily used to assess the likelihood of ignition during processing and handling. The likelihood of ignition is used to evaluate the need for precautions such as explosion prevention systems. The MIE is determined as the electrical energy stored in a capacitor which, when released as a high voltage spark, is just sufficient to ignite the dust cloud at its most easily ignitable concentration in air. The laboratory test method described in this standard does not optimize all test variables that affect MIE. Smaller MIE values might be determined by increasing the number of repetitions or optimizing the spark discharge circuit for each dust tested.  
1.3 In this test method, the test equipment is calibrated using a series of reference dusts whose MIE values lie within established limits. Once the test equipment is calibrated, the relative ignition sensitivity of other dusts can be found by comparing their MIE values with those of the reference dusts or with dusts whose ignition sensitivities are known from experience. X1.1 of this test method includes guidance on the significance of minimum ignition energy with respect to electrostatic discharges.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.  
1.6 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.

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ASTM E1491-06(2019)(Test Method)
Standard Test Method for Minimum Autoignition Temperature of Dust Clouds

SIGNIFICANCE AND USE
5.1 This test method provides a procedure for performing laboratory tests to determine the minimum autoignition temperature (MAIT) of a dust cloud.  
5.2 The test data developed from this test method can be used to limit the temperature to which a dust cloud is exposed so as to prevent ignition of the cloud. Because of the short duration of the test, the data obtained are most applicable to industrial equipment where dust is present as a cloud for a short time. Because of the small scale of the test and the possible variation of the MAIT value with scale, the data obtained by this test method may not be directly applicable to all industrial conditions.  
5.3 The MAIT data can also be used in conjunction with minimum spark ignition data to evaluate the hazards of grinding and impact sparks in the presence of dust clouds (1 and 2).3  
5.4 The test values obtained are specific to the sample tested, the method used, and the test equipment utilized. The test values are not to be considered intrinsic material constants, but may be used as a relative measure of the temperature at which a dust cloud self ignites.  
5.5 The test data are for cloud ignition. Dust in the form of a layer may ignite at significantly lower temperatures than the same dust in the form of a cloud (3). For liquid chemicals, see Test Method E659.
SCOPE
1.1 This test method covers the minimum temperature at which a given dust cloud will autoignite when exposed to air heated in a furnace at local atmospheric pressure.  
1.2 Data obtained from this test method provide a relative measure of dust cloud autoignition temperatures.  
1.3 This test method 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 method 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.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

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ASTM G126-16(2023)(Terminology)
Standard Terminology Relating to the Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres

SCOPE
1.1 This terminology defines terms related to the compatibility and sensitivity of materials in oxygen enriched atmospheres. It includes those standards under the jurisdiction of ASTM Committee G04.  
1.2 The terminology concentrates on terms commonly encountered in and specific to practices and methods used to evaluate the compatibility and sensitivity of materials in oxygen. This evaluation is usually performed in a laboratory environment, and this terminology does not attempt to include laboratory terms.  
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.

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ASTM E2021-15(2023)(Test Method)
Standard Test Method for Hot-Surface Ignition Temperature of Dust Layers

SIGNIFICANCE AND USE
5.1 This test method is applicable to dusts and powders, and provides a procedure for performing laboratory tests to evaluate hot-surface ignition temperatures of dust layers.  
5.2 The test data can be of value in determining safe operating conditions in industrial plants, mines, manufacturing processes, and locations of material usage and storage.  
5.3 Due to variation of ignition temperature with layer thickness, the test data at one thickness may not be applicable to all industrial situations (see Appendix X1). Tests at various layer thicknesses may provide a means for extrapolation to thicker layers, as listed in the following for pulverized Pittsburgh bituminous coal dust (2). Mathematical modeling of layer ignition at various layer thicknesses is described in Ref. (3).
Layer Thickness, mm  
Hot-Surface Ignition Temperature, °C  
6.4  
300  
9.4  
260  
12.7  
240  
25.4  
210  
5.4 This hot plate test method allows for loss of heat from the top surface of the dust layer, and therefore generally gives a higher ignition temperature for a material than Test Method E771, which is a more adiabatic system.  
5.5 This test method for dust layers generally will give a lower ignition temperature than Test Method E1491, which is for dust clouds. The layer ignition temperature is determined while monitoring for periods of minutes to hours, while the dust cloud is only exposed to the furnace for a period of seconds.
Note 1: Much of the literature data for layer ignition is actually from a basket in a heated furnace (4), known as the modified Godbert-Greenwald furnace test. Other data are from nonstandardized hot plates (5-9).  
5.6 Additional information on the significance and use of this test method may be found in Ref. (10).
SCOPE
1.1 This test method covers a laboratory procedure to determine the hot-surface ignition temperature of dust layers, that is, measuring the minimum temperature at which a dust layer will self-heat. The test consists of a dust layer heated on a hot plate.2,3  
1.2 Data obtained from this test method provide a relative measure of the hot-surface ignition temperature of a dust layer.  
1.3 This test method should be used to measure and describe the properties of materials in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire hazard risk of materials, products, or assemblies under actual fire conditions. However, results of this test method may be used as elements of a fire risk assessment that takes into account all of the factors that are pertinent to an assessment of the fire hazard risk of a particular end use product.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.  
1.6 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.

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ASTM E1515-14(2022)(Test Method)
Standard Test Method for Minimum Explosible Concentration of Combustible Dusts

SIGNIFICANCE AND USE
5.1 This test method provides a procedure for performing laboratory tests to evaluate relative deflagration parameters of dusts.  
5.2 The MEC as measured by this test method provides a relative measure of the concentration of a dust cloud necessary for an explosion.  
5.3 Since the MEC as measured by this test method may vary with the uniformity of the dust dispersion, energy of the ignitor, and propagation criteria, the MEC should be considered a relative rather than absolute measurement.  
5.4 If too weak an ignition source is used, the measured MEC would be higher than the “true” value. This is an ignitability limit rather than a flammability limit, and the test could be described as “underdriven.” Ideally, the ignition energy is increased until the measured MEC is independent of ignition energy. However, at some point the ignition energy may become too strong for the size of the test chamber, and the system becomes “overdriven.” When the ignitor flame becomes too large relative to the chamber volume, a test could appear to result in an explosion, while it is actually just dust burning in the ignitor flame with no real propagation beyond the ignitor.  
5.5 The recommended ignition source for measuring the MEC of dusts in 20-L chambers is a 2500 or 5000 J pyrotechnic ignitor.4 Measuring the MEC at both ignition energies will provide information on the possible overdriving of the system.5 To evaluate the effect of possible overdriving in a 20-L chamber, comparison tests may also be made in a larger chamber, such as a 1 m3-chamber.  
5.6 If a dust ignites with a 5000 J ignitor but not with a 2500 J ignitor in a 20-L chamber, this may be an overdriven system.5 In this case, it is recommended that the dust be tested with a 10 000 J ignitor in a larger chamber, such as a 1 m3-chamber, to determine if it is actually explosible.  
5.7 The values obtained by this test method are specific to the sample tested (particularly the particle size distribution) and the met...
SCOPE
1.1 This test method covers the determination of the minimum concentration of a dust-air mixture that will propagate a deflagration in a near-spherical closed vessel of 20 L or greater volume.
Note 1: The minimum explosible concentration (MEC) is also referred to as the lower explosibility limit (LEL) or lean flammability limit (LFL).  
1.2 Data obtained from this test method provide a relative measure of the deflagration characteristics of dust clouds.  
1.3 This test method should be used to measure and describe the properties of materials 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 that takes into account all of the factors that are pertinent to an assessment of the fire hazard of a particular end use.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  Specific precautionary statements are given in Section 8.  
1.6 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.

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