ASTM E1515-14(2022)
(Test Method)Standard Test Method for Minimum Explosible Concentration of Combustible Dusts
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.
General Information
Relations
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:E1515 −14 (Reapproved 2022)
Standard Test Method for
Minimum Explosible Concentration of Combustible Dusts
This standard is issued under the fixed designation E1515; 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 describes procedures for measuring the minimum concentration of a combustible
dust (dispersed in air) that is capable of propagating a deflagration. The tests are made in laboratory
chambers that have volumes of 20 L or larger.
1. Scope ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This test method covers the determination of the mini-
mendations issued by the World Trade Organization Technical
mum concentration of a dust-air mixture that will propagate a
Barriers to Trade (TBT) Committee.
deflagration in a near-spherical closed vessel of 20 Lor greater
volume.
2. Referenced Documents
NOTE 1—The minimum explosible concentration (MEC) is also re-
2.1 ASTM Standards:
ferred to as the lower explosibility limit (LEL) or lean flammability limit
D3173 Test Method for Moisture in the Analysis Sample of
(LFL).
Coal and Coke
1.2 Data obtained from this test method provide a relative
D3175 Test Method for Volatile Matter in the Analysis
measure of the deflagration characteristics of dust clouds.
Sample of Coal and Coke
1.3 Thistestmethodshouldbeusedtomeasureanddescribe
E681 Test Method for Concentration Limits of Flammability
the properties of materials in response to heat and flame under
of Chemicals (Vapors and Gases)
controlled laboratory conditions and should not be used to
E1226 Test Method for Explosibility of Dust Clouds
describe or appraise the fire hazard or fire risk of materials,
2.2 CEN/CENELEC Publications:
products, or assemblies under actual fire conditions. However,
EN 14034–3 Determination of Explosion Characteristics of
results of this test may be used as elements of a fire risk
Dust Clouds – Part 3: Determination of the Lower
assessment that takes into account all of the factors that are
Explosion Limit LEL of Dust Clouds
pertinent to an assessment of the fire hazard of a particular end
use.
3. Terminology
1.4 The values stated in SI units are to be regarded as
3.1 Definitions of Terms Specific to This Standard:
standard. No other units of measurement are included in this
3.1.1 dust concentration, n—the mass of dust divided by the
standard.
internal volume of the test chamber.
1.5 This standard does not purport to address all of the
3.1.2 (dP/dt) ,n—themaximumrateofpressureriseduring
ex
safety concerns, if any, associated with its use. It is the
the course of a single deflagration test.
responsibility of the user of this standard to establish appro-
3.1.3 minimum explosible concentration (MEC), n—the
priate safety, health, and environmental practices and deter-
minimum concentration of a combustible dust cloud that is
mine the applicability of regulatory limitations prior to use.
capable of propagating a deflagration through a well dispersed
Specific precautionary statements are given in Section 8.
mixture of the dust and air under the specified conditions of
1.6 This international standard was developed in accor-
test.
dance with internationally recognized principles on standard-
1 2
This test method is under the jurisdiction ofASTM Committee E27 on Hazard For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Potential of Chemicals and is the direct responsibility of Subcommittee E27.05 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Explosibility and Ignitability of Dust Clouds. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved June 1, 2022. Published June 2022. Originally the ASTM website.
approved in 1993. Last previous edition approved in 2014 as E1515 – 14. DOI: Available from European Committee for Standardization (CEN), Avenue
10.1520/E1515-14R22. Marnix 17, B-1000, Brussels, Belgium, http://www.cen.eu.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1515−14 (2022)
3.1.4 P ,n—the absolute pressure at the time the ignitor, and propagation criteria, the MEC should be consid-
ignition
ignitor is activated, see Fig. 1. ered a relative rather than absolute measurement.
3.1.5 ∆P ,n—thepressureriseinthechamberduetothe
ignitor
5.4 If too weak an ignition source is used, the measured
ignitor by itself in air at atmospheric pressure
MEC would be higher than the “true” value. This is an
3.1.6 P ,n—the maximum explosion pressure (absolute)
ex,a ignitability limit rather than a flammability limit, and the test
reachedduringthecourseofasingledeflagrationtest(seeFigs.
could be described as “underdriven.” Ideally, the ignition
1 and 2).
energy is increased until the measured MEC is independent of
3.1.7 P ,n—maximum pressure rise produced during the ignition energy. However, at some point the ignition energy
m
course of a single deflagration test that is corrected for the
may become too strong for the size of the test chamber, and the
effects of ignitor pressure and cooling in the 20-L vessel (see
system becomes “overdriven.” When the ignitor flame be-
Test Method E1226, Sections X1.8 and X1.9).
comes too large relative to the chamber volume, a test could
3.1.7.1 Discussion—When testing in the Siwek 20-L vessel
appear to result in an explosion, while it is actually just dust
(see Test Method E1226,Appendix X1) PR may be calculated
burning in the ignitor flame with no real propagation beyond
using the corrected explosion pressure:
the ignitor.
PR 5 ~P 1 P !⁄P (1)
m ignition ignition
5.5 The recommended ignition source for measuring the
3.1.8 pressure ratio (PR), n—defined as:
MEC of dusts in 20-L chambers is a 2500 or 5000 J
PR 5 ~P 1 ∆ P !⁄P (2) pyrotechnic ignitor. Measuring the MEC at both ignition
ex,a ignitor ignition
energies will provide information on the possible overdriving
4. Summary of Test Method
of the system. To evaluate the effect of possible overdriving in
a 20-Lchamber, comparison tests may also be made in a larger
4.1 Adust cloud is formed in a closed combustion chamber
by an introduction of the material with air. The test is normally chamber, such asa1m -chamber.
made at atmospheric pressure.
5.6 Ifadustigniteswitha5000Jignitorbutnotwitha2500
4.2 Ignition of this dust-air mixture is then attempted after a
Jignitorina20-Lchamber,thismaybeanoverdrivensystem.
specified delay time by an ignition source located near the
In this case, it is recommended that the dust be tested with a
center of the chamber.
10 000 J ignitor in a larger chamber, such asa1m -chamber,
4.3 The pressure time curve is recorded on a suitable piece to determine if it is actually explosible.
of equipment.
5.7 The values obtained by this test method are specific to
the sample tested (particularly the particle size distribution)
5. Significance and Use
and the method used and are not to be considered intrinsic
5.1 This test method provides a procedure for performing
material constants.
laboratory tests to evaluate relative deflagration parameters of
dusts.
5.2 The MEC as measured by this test method provides a
The pyrotechnic ignitors are available commercially from Cesana Corp., PO
relative measure of the concentration of a dust cloud necessary
Box 182,Verona, NY13478, or from Fr. Sobbe, GmbH, Beylingstrasse 59, Postfach
for an explosion. 140128, D-4600 Dortmund-Derne, Germany.
Cashdollar, K. L., and Chatrathi, K., “Minimum Explosible Dust Concentra-
5.3 Since the MEC as measured by this test method may 3
tions Measured in 20-Land 1-m Chambers,” Combustion Science and Technology,
vary with the uniformity of the dust dispersion, energy of the
Vol 87, 1993, pp. 157–171.
FIG. 1Typical Recorder Tracings for a Weak Dust Deflagration in a 20-L Chamber, using a 2500 J Ignitor
E1515−14 (2022)
FIG. 2Typical Recorder Tracings for a Moderate Dust Deflagration in a 20-L Chamber, using a 2500 J Ignitor
6. Interferences 8. Safety Precautions
6.1 Unburned dust or combustion products remaining in the 8.1 Prior to handling a dust, the toxicity of the sample and
chamber or disperser from a previous test may affect results. its combustion products must be considered. This information
The chamber and disperser should both be cleaned thoroughly is generally obtained from the manufacturer or supplier.
before each test is made. Appropriate safety precautions must be taken if the material
has toxic or irritating characteristics. Tests using this apparatus
7. Apparatus should be conducted in a ventilated hood or other area having
adequate ventilation.
7.1 The equipment consists of a closed steel combustion
chamber with an internal volume of at least 20 L, spherical or 8.2 Before initiating a test, a physical check of all gaskets
cylindrical (with a length to diameter ratio between 1.3:1 and
and fittings should be made to prevent leakage.
0.7:1) in shape.
8.3 If chemical ignitors are used as an ignitor source, safety
7.2 The vessel should be designed and fabricated in accor-
in handling and use is a primary consideration. Premature
dance with the ASME Boiler and Pressure Vessel Code,
ignition by electrostatic discharge must be considered a possi-
Section VIII. A maximum allowable working pressure
bility. When handling these ignitors, eye protection must be
(MAWP) of at least 15 bar is recommended.
worn at all times. A grounded, conductive tabletop is recom-
mended for preparation. Federal, state, and local regulations
7.3 The apparatus must be capable of dispersing a fairly
for the procurement, use, and storage of chemical ignitors must
uniform dust cloud of the material.
be followed.
7.4 Optical dust probes, such as those described in
7,8
8.4 All testing should initially be conducted with small
Footnotes may be used to monitor the uniformity of the dust
quantities of sample to prevent overpressurization due to high
dispersion.
energy material.
7.5 The pressure transducer and recording equipment must
8.5 Explosive, highly reactive, or easily decomposed mate-
have a combined response rate that is greater than the maxi-
rials should not be tested unless they have been characterized
mum measured rate of pressure rise.
by prior testing. Procedures such as the use of barricades,
7.6 An example of a chamber and specific procedures that
hoods, and personal protective equipment should be used as
have been found suitable are shown in Appendix X1.
judgment indicates.
NOTE 2—Another 20 Lchamber design is described inAppendix X1 of
9. Sampling, Test Specimens, and Test Units
Test Method E1226.
9.1 It is not practical to specify a single method of sampling
dust for test purposes because the character of the material and
Available from American Society of Mechanical Engineers (ASME), ASME
its available form affect selection of the sampling procedure.
International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
Generally accepted sampling procedures should be used as
www.asme.org.
described in MNL 32.
Cashdollar, K. L., Liebman, I., and Conti, R. S., “Three Bureau of Mines Dust
Probes,” RI 8542, U.S. Bureau of Mines, 1981.
Conti, R. S., Cashdollar, K. L., and Liebman, I., “Improved Optical Dust Probe
forMonitoringDustExplosions,” Review of Scientific Instruments,Vol53,1982,pp. MNL 32, Manual on testing Sieving Methods, is available from ASTM
311–313. Headquarters, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
E1515−14 (2022)
B 3
1-m Chamber at Blue Springs, MO. See Cashdollar, K. L. and Chatrathi, K.,
9.2 Tests may be run on an as-received sample. However,
“Minimum Explosible Concentrations in 20-L and 1-m Chambers,” Combustion
due to the possible accumulation of fines at some location in a
Science and Technology, Vol 87, 1993, pp. 157–171.
processing system, it is recommended that the test sample be at
The Pocahontas seam bituminous coal has ;75 % minus
least 95 % minus 200 mesh (75 µm).
200 mesh, a mass median diameter of ;52 µm, and 17 %
9.3 To achieve this particle fineness (≥95 % minus 200
volatility. The Pittsburgh seam bituminous coal has ;80 %
mesh), the sample may be ground or pulverized or it may be
minus 200 mesh, a mass median diameter of ;48 µm, and
sieved.
36 % volatility.The lycopodium is a natural plant spore having
a narrow size distribution with 100 % minus 200 mesh and a
NOTE 3—The operator should consider the thermal stability and the
friction and impact sensitivity of the dust during any grinding or mass median diameter of ;28 µm. The gilsonite has ;91 %
pulverizing. In sieving the material, the operator must verify that there is
minus 200 mesh, a mass median diameter of ;28 µm, and
no selective separation of components in a dust that is not a pure
84 % volatility. The polyethylene has ;98 % minus 200 mesh,
substance.
a mass median diameter of ;29 µm, and 100 % volatility.
9.4 Dustsamplesthataremuchfinerthan200mesh(75µm)
10.3 In addition to the initial calibration and standardization
may have even lower MEC values.
procedure,atleastonereferencedustsampleshouldberetested
NOTE 4—It may be desirable in some cases to conduct dust deflagration periodically to verify that the dispersion and other character-
tests on materials as sampled from a process because process dust streams
istics of the chamber have not changed.
may contain a wide range of particle sizes or have a well-defined specific
moisture content. Materials consisting of a mixture of chemicals may be
11. Procedure
selectively separated on sieves and certain fibrous materials that may not
pass through a relatively coarse screen may produce dust deflagrations.
11.1 These general procedures are applicable for all suitable
When a material is tested in the as-received state, it should be recognized
chambers. The detailed procedures specific to each chamber
that the test results may not represent the most severe dust deflagration
are listed in Appendix X1.
possible. Any process change resulting in a higher fraction of fines than
normal or drier product than normal may increase the explosion severity.
11.2 Inspect equipment to be sure it is thoroughly clean and
9.5 The moisture content of the test sample should not
in good operational condition.
exc
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