ASTM E582-07(2013)e1
(Test Method)Standard Test Method for Minimum Ignition Energy and Quenching Distance in Gaseous Mixtures
Standard Test Method for Minimum Ignition Energy and Quenching Distance in Gaseous Mixtures
SIGNIFICANCE AND USE
3.1 The minimum energies provide a basis for comparing the ease of ignition of gases. The flatplate ignition quenching distances provide an important verification of existing minimum ignition energy data and give approximate values of the propagation quenching distances of the various mixtures. It is emphasized that maximum safe experimental gaps, as from “flame-proof” or “explosion-proof” studies, are less than the flat-plate ignition quenching distances.
SCOPE
1.1 This test method covers the determination of minimum energy for ignition (initiation of deflagration) and associated flat-plate ignition quenching distances.2 The complete description is specific to alkane or alkene fuels admixed with air at normal ambient temperature and pressure. This method is applicable to mixtures of the specified fuels with air, varying from the most easily ignitable mixture to mixtures near to the limit-of-flammability compositions.
1.2 Extensions to other fuel-oxidizer combinations, and to other temperatures and pressures can be accomplished with all the accuracy inherent in this method if certain additional conditions are met: ( a) mixture stability and compatibility with bomb, seal, and other materials is established through time tests described in Section 9; (b) the expected peak pressure from the test is within the pressure rating of the bomb (established as required by the particular research laboratory); (c) spark breakdown within the bomb is consistent with Paschen's law for the distance being tested; (d) the temperature, including that of the discharge electrodes, is uniform; and (e) if the temperature is other than ambient, the energy storage capacitance required is less than about 9 pF.
1.3 This method is one of several being developed by Committee E27 for determining the hazards of chemicals, including their vapors in air or other oxidant atmospheres. The measurements are useful in assessing fuel ignitability hazards due to static or other electrical sparks. However, the quenching distance data must be used with great prudence since they are primarily applicable to the ignition stage and therefore, represent values for initial pressure and not the smaller values existing at higher pressures.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 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.
1.6 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. Specific safety precautions are listed in Section 5.
General Information
Standards Content (Sample)
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Designation: E582 − 07 (Reapproved 2013)
Standard Test Method for
Minimum Ignition Energy and Quenching Distance in
Gaseous Mixtures
This standard is issued under the fixed designation E582; 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.
ε NOTE—Warning notes were editorially updated throughout in October 2013.
1. Scope 1.4 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
1.1 This test method covers the determination of minimum
conversions to SI units that are provided for information only
energy for ignition (initiation of deflagration) and associated
2 and are not considered standard.
flat-plate ignition quenching distances. The complete descrip-
1.5 This standard should be used to measure and describe
tion is specific to alkane or alkene fuels admixed with air at
the properties of materials, products, or assemblies in response
normal ambient temperature and pressure. This method is
to heat and flame under controlled laboratory conditions and
applicable to mixtures of the specified fuels with air, varying
should not be used to describe or appraise the fire hazard or
from the most easily ignitable mixture to mixtures near to the
fire risk of materials, products, or assemblies under actual fire
limit-of-flammability compositions.
conditions. However, results of this test may be used as
1.2 Extensions to other fuel-oxidizer combinations, and to
elements of a fire risk assessment which takes into account all
other temperatures and pressures can be accomplished with all
of the factors which are pertinent to an assessment of the fire
the accuracy inherent in this method if certain additional
hazard of a particular end use.
conditions are met: (a) mixture stability and compatibility with
1.6 This standard does not purport to address all of the
bomb, seal, and other materials is established through time
safety concerns, if any, associated with its use. It is the
tests described in Section 9;(b) the expected peak pressure
responsibility of the user of this standard to establish appro-
from the test is within the pressure rating of the bomb
priate safety and health practices and determine the applica-
(established as required by the particular research laboratory);
bility of regulatory limitations prior to use. Specific safety
(c) spark breakdown within the bomb is consistent with
precautions are listed in Section 5.
Paschen’s law for the distance being tested; (d) the
temperature, including that of the discharge electrodes, is
2. Terminology
uniform; and (e) if the temperature is other than ambient, the
2.1 Definitions:
energy storage capacitance required is less than about 9 pF.
2.1.1 ignition, n—the initiation of combustion.
1.3 This method is one of several being developed by
2.1.2 minimum ignition energy (MIE), n—electrical energy
Committee E27 for determining the hazards of chemicals,
discharged from a capacitor, which is just sufficient to effect
including their vapors in air or other oxidant atmospheres. The
ignition of the most easily ignitable concentration of fuel in air
measurements are useful in assessing fuel ignitability hazards
under the specific test conditions.
due to static or other electrical sparks. However, the quenching
distance data must be used with great prudence since they are 2.2 Definitions of Terms Specific to This Standard:
primarily applicable to the ignition stage and therefore, repre- 2.2.1 ignition quenching distance, n—maximum spacing
sent values for initial pressure and not the smaller values between eletrode flanges that will not permit spark ignition and
existing at higher pressures. flame propagation beyond the flanges, when tested under the
specified test conditions.
3. Significance and Use
This test method is under the jurisdiction ofASTM Committee E27 on Hazard
Potential of Chemicals and is the direct responsibility of Subcommittee E27.04 on
3.1 The minimum energies provide a basis for comparing
Flammability and Ignitability of Chemicals.
the ease of ignition of gases. The flatplate ignition quenching
Current edition approved Oct. 1, 2013. Published November 2013. Originally
approved in 1976. Last previous edition approved in 2007 as E582 – 07. DOI:
distances provide an important verification of existing mini-
10.1520/E0582-07R13E01.
mum ignition energy data and give approximate values of the
Litchfield, E. L., Hay, M. H., Kubala, T. S., and Monroe, J. S., “Minimum
propagation quenching distances of the various mixtures. It is
Ignition Energy and Quenching Distance in Gaseous Mixtures,” BuMines,R.L.
7009, August 1967, p. 11. emphasized that maximum safe experimental gaps, as from
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E582 − 07 (2013)
“flame-proof” or “explosion-proof” studies, are less than the vessel volume. The reaction vessel provides for opposed
flat-plate ignition quenching distances. mounting of the spark electrodes which permits rapid and
convenient variation of the gap length without the necessity for
4. Apparatus
opening the vessel. The input orifice (Fig. 2, Section A-A)is
4.1 Reaction Vessel—The recommended reaction vessel is located so that the gases are introduced approximately tangen-
manufactured according to the specifications of Fig. 1 and Fig. tially to the vessel walls, thus providing a turbulent swirling
2. This is a spherical vessel, manufactured of Type 304 motion that facilitates mixing. A sight glass permits direct
stainless steel, and passivated after machining. The spherical observation of flame initiation and propagation throughout the
geometry maximizes the useable spark-gap length for a given reaction volume.
NOTE 1—Tolerance is 60.010 in., unless noted.
NOTE 2—Break all sharp edges.
NOTE 3—Material is Type 304 stainless steel.
NOTE 4—Thread depth is 75 to 80 %.
NOTE 5—1 in. = 25.4 mm.
FIG. 1 Electrode Assembly (I)
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E582 − 07 (2013)
NOTE 1—Tolerance is 60.010 in., unless noted.
NOTE 2—Break all sharp edges.
NOTE 3—Material is Type 304 stainless steel.
NOTE 4—Thread depth is 75 to 80 %.
NOTE 5—1 in. = 25.4 mm.
FIG. 2 Electrode Assembly (II).
4.2 Electrode Assembly: be planar and coplanar to 0.001 in. (0.025 mm) or 1 % of the
4.2.1 The electrodes (Fig. 1) have metal tips flanged with intended test gap, whichever is larger.
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glass plates. The tips screw into ⁄8-in. stainless steel rods 4.2.2 Two inserts are required to carry the ⁄8-in. rods
which extend through inserts in the bomb walls to permit through the walls of the reaction vessel. At least one of these
external electrical connections. Gas seals are provided between inserts must be made of high-electrical resistivity insulating
the reaction vessel and the inserts and between the inserts and material. Hard rubber, phenolic plastic, poly(methyl methacry-
the ⁄8-in. rods by O-ring seals (see Fig. 2, Assembly). The alate) (PMMA), and many other materials are suitable for use
glass flange material should be either borosilicate or high silica with the alkane and alkene fuels. In the excepted cases (other
and the flanges should be fastened to the stainless steel tips similarlyenergeticfuels),theinsulatingmaterialmustnotreact
with a thin layer of epoxy cement. The facing surfaces should with or absorb the fuel being tested.
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E582 − 07 (2013)
4.2.3 Where the test arrangement is optimized through the testing flexibility, the power supply should deliver variable or
use of a “double-ended’’ power supply, (see Fig. 3(b)) two adjustable output voltage differences between 1 and 30 kV.
insulating inserts are required. Otherwise, one of the inserts
NOTE 1—The double-ended power supply should be used only in
may be machined from Type 304 stainless steel.
conjunction with two insulating inserts. The metal bomb structure must
4.2.4 Insulation between the two electrodes should exceed
then be connected to the power supply center point and connected to
10 Ω as discussed in 4.3.3. system ground. The double-ended power supply gives somewhat higher
gap breakdown voltages at larger spark gaps and, thus, somewhat lower
4.2.5 Measurement of the gap width is made by available
ignition energies. This consideration should be of importance only if the
techniques and implements most suitable for the gap distance
very highest quality data are required.
being measured. Calibrated leaf gages, inside micrometers, or
4.3.3 The output filter capacitors of the power supply must
vernier calipers are suitable, depending upon the gap distance.
be isolated from the discharge energy storage capacitance by
The measurements should be made with a repeatability of
an isolating resistor. The resistive-capacitive time constant of
60.001 in. (0.025 mm) or 1 %, whichever is most conserva-
the charging circuit containing the energy storage capacitance
tive. To facilitate such measurements, it is helpful to have leaf
should be several seconds; 10 Ω is a desirable value for the
gages of known thicknesses for frequently used gap distances.
most easily ignitable mixture (energy storage capacitance of 8
High-quality machinist’s micrometers will generally provide
to 12 pF) with the value reduced inversely as the energy
adequate accuracy.
storage capacitance is increased for less easily ignitable mix-
4.3 Power Supply and Electrical Circuit:
tures. Two resistors should be used in series, four with the
4.3.1 The power supply should be of the oscillator type, so
double-ended supply. One resistor shall be immediately at the
that its filter condensers will be electrically small. The maxi-
power supply terminal, the other at the bomb energy storage
mum output current should be about 1 mA. (Warning—With
capacitance. Supply-line electrical insulation needs to be
such a power supply, the probability of lethal shock to the
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greater than 10 Ω to be consistent with 10 Ω series
operator from the high-voltage circuits becomes negligible.
resistance. Such resistance is most easily achieved through air
However, all usual
...
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