ISO/IEC 80079-20-2:2016
(Main)Explosive atmospheres — Part 20-2: Material characteristics — Combustible dusts test methods
Explosive atmospheres — Part 20-2: Material characteristics — Combustible dusts test methods
ISO/IEC 80079-20-2:2016 is published as a dual logo standard and describes the test methods for the identification of combustible dust and combustible dust layers in order to permit classification of areas where such materials exist for the purpose of the proper selection and installation of electrical and mechanical equipment for use in the presence of combustible dust. The standard atmospheric conditions for determination of characteristics of combustible dusts are: - temperature -20 °C to 60 °C, - pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar) and - air with normal oxygen content, typically 21 % v/v. The test methods defined do not apply to: - recognized explosives, propellants (e.g. gunpowder, dynamite), or substances or mixtures of substances which may, under some circumstances, behave in a similar manner or - dusts of explosives and propellants that do not require atmospheric oxygen for combustion, or to pyrophoric substances. This first edition cancels and replaces the first edition of IEC 61241-2-1 published in 1994, the first edition of IEC 61241-2-2 published in 1993 and the first edition of IEC 61241-2-3 published in 1994, combining the requirements into a single document, and is considered to constitute a technical revision. Significant changes with respect to IEC 61241-2-1:1994, IEC 61241-2-2:1993 and IEC 61241-2-3:1994 can be found in the foreword of the document. Keywords: combustible dust
Atmosphères explosives — Partie 20-2: Caractéristiques des produits — Méthodes d’essai des poussières combustibles
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Standards Content (Sample)
ISO/IEC 80079-20-2
Edition 1.0 2016-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 20-2: Material characteristics – Combustible dusts test methods
Atmosphères explosives –
Partie 20-2: Caractéristiques des produits – Méthodes d’essai des poussières
combustibles
ISO/IEC 80079-20-2:2016-02(en-fr)
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ISO/IEC 80079-20-2
Edition 1.0 2016-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 20-2: Material characteristics – Combustible dusts test methods
Atmosphères explosives –
Partie 20-2: Caractéristiques des produits – Méthodes d’essai des poussières
combustibles
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.230; 29.260.20 ISBN 978-2-8322-3179-1
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
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– 2 – ISO/IEC 80079-20-2:2016
ISO/IEC 2016
CONTENTS
FOREWORD . 5
1 Scope . 8
2 Normative references. 8
3 Terms and definitions . 8
4 Dust sample requirements . 9
4.1 Receipt of sample for testing . 9
4.2 Characterisation of sample . 9
4.3 Preparation of sample . 10
4.4 Test conditions . 10
5 Combustible dusts and combustible flyings determination . 10
5.1 Test sequence . 10
5.2 Tests to determine whether material is a combustible dust or combustible
flying . 10
5.2.1 Visual inspection . 10
5.2.2 Determine particle distribution . 11
5.2.3 Ignition test in the Hartmann tube . 11
5.2.4 Ignition test in the 20-litre sphere . 11
6 Procedure for characterisation of combustible dust or combustible flying . 11
7 Test methods for determination of whether a material is a combustible dust or a
combustible flying . 14
7.1 Modified Hartmann tube . 14
7.1.1 General . 14
7.1.2 Test equipment . 14
7.1.3 Test procedure . 15
7.2 20-litre sphere . 15
7.2.1 General . 15
7.2.2 Test equipment . 15
7.2.3 Test procedure . 16
7.3 Alternative method to 20-litre sphere for small test material quantities . 16
7.3.1 General . 16
7.3.2 Test equipment . 17
7.3.3 Test procedure . 17
8 Test methods for combustible dust determinations . 17
8.1 MIT of a dust cloud . 17
8.1.1 General . 17
8.1.2 GG furnace . 17
8.1.3 BAM furnace . 18
8.2 Test for MIT of dust layer . 19
8.2.1 General . 19
8.2.2 Heated surface . 19
8.2.3 Dust layers . 20
8.2.4 Dust layer temperature . 20
8.2.5 Ambient temperature measurements . 20
8.2.6 Dust layer temperature test method . 20
8.2.7 Recording of results . 21
8.3 Method for determining minimum ignition energy of dust/air mixtures . 22
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ISO/IEC 80079-20-2:2016 – 3 –
ISO/IEC 2016
8.3.1 General . 22
8.3.2 Test equipment . 22
8.3.3 Test procedure . 23
8.3.4 Calibration for determination of minimum ignition energies (MIE) by
electrically generated high-voltage d.c. sparks . 24
8.3.5 Recording of test results . 24
8.4 Test on resistivity . 24
8.4.1 General . 24
8.4.2 Test equipment . 25
8.4.3 Test procedure . 25
8.4.4 Recording of test results . 26
9 Test report. 26
Annex A (normative) Measurement of temperature distribution on the surface of the
hot plate . 27
Annex B (informative) Godbert-Greenwald oven (GG) . 28
Annex C (informative) Examples of spark-generating systems . 29
C.1 General . 29
C.2 Triggering by auxiliary spark using three-electrode system . 30
C.3 Triggering by electrode movement . 31
C.4 Triggering by voltage increase (trickle-charging circuit) . 32
C.5 Triggering by auxiliary spark, using normal two-electrode system – Trigger
transformer in discharge circuit . 33
Annex D (normative) Vertical tube (modified Hartmann tube) apparatus . 34
Annex E (informative) 20-litre sphere . 35
Annex F (informative) BAM oven . 37
Annex G (informative) Data for dust explosion characteristics . 38
3
Annex H (informative) 1 m vessel . 39
H.1 Test principle . 39
H.2 Test apparatus . 39
H.3 Test conditions . 43
H.4 Test procedure . 43
Bibliography . 45
Figure 1 – Protocol for characterisation of combustible dust or combustible flying . 12
Figure 2 – Tests to define ability to form explosive dust atmosphere (combustible
dust/combustible flyings) . 13
Figure 3 – Tests to characterise combustible dust or combustible flying . 14
Figure 4 – Modified Hartmann tube . 23
Figure 5 – Measuring cell for powder resistivity . 25
Figure A.1 – Typical surface temperature distribution (method A) . 27
Figure B.1 – Vertical cross-section through the Godbert-Greenwald oven . 28
Figure C.1 – Circuit – Triggering by high-voltage relay, using a two-electrode system . 29
Figure C.2 – Apparatus for determining the minimum ignition energies of dust
(schematic) – Triggering by auxiliary spark using three-electrode system . 30
Figure C.3 – Apparatus for determining the minimum ignition energies of dust
(schematic) – Triggering by electrode movement . 31
Figure C.4 – Apparatus for determining the minimum ignition energies of dust
(schematic) – Triggering by voltage increase . 32
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ISO/IEC 2016
Figure C.5 – Apparatus for determining the minimum ignition energies for dust
(schematic) – Trigger transformer in discharge circuit . 33
Figure D.1 – Vertical tube apparatus (modified Hartmann tube) . 34
Figure E.1 – Test equipment 20-litre sphere (schematic) . 35
Figure E.2 – Cross-sectional view of rebound nozzle . 36
Figure E.3 – Plan view of rebound nozzle . 36
Figure E.4 – Cross-sectional view of dispersion cup . 36
Figure F.1 – Cross-sectional arrangement of BAM oven . 37
3
Figure H.1 – 1 m vessel (schematic) . 40
Figure H.2 – Location of the 6 mm holes in the semicircular dust dispenser . 41
Figure H.3 – Rebound nozzle . 42
Figure H.4 – Dispersion cup . 43
Table 1 – Example of ignition test report . 21
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ISO/IEC 80079-20-2:2016 – 5 –
ISO/IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPLOSIVE ATMOSPHERES –
Part 20-2: Material characteristics –
Combustible dusts test methods
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard ISO/IEC 80079-20-2 has been prepared by subcommittee 31M: Non-
electrical equipment and protective systems for explosive atmospheres, of IEC 31: Equipment
for explosive atmospheres.
It is published as a double logo standard.
This first edition cancels and replaces the first edition of IEC 61241-2-1 published in 1994, the
first edition of IEC 61241-2-2 published in 1993 and the first edition of IEC 61241-2-3
published in 1994, combining the requirements into a single document, and is considered to
constitute a technical revision.
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ISO/IEC 2016
The text of this standard is based on the following documents:
FDIS Report on voting
31M/102/FDIS 31M/108/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table. In ISO, the standard has been approved by 15 P-members
out of 21 having cast a vote.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
"A list of all parts in the IEC 60079 series, under the general title Explosive atmospheres, as
well as the International Standard 80079 series, can be found on the IEC website."
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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ISO/IEC 80079-20-2:2016 – 7 –
ISO/IEC 2016
Significant changes with respect to IEC 61241-2-1:1994, IEC 61241-2-2:1993 and
IEC 61241-2-3:1994
Type
Explanation of the significance of the Clause Minor and Extension Major technical
changes editorial changes changes
Normative references 2 X
Terms and Definitions 3 X
Dust sample Requirements 4 X
Combustible Dust Determination 5 X
Procedure for Characterisation of combustible 6 X
dust or combustible flying
Test methods for determination of a 7 X
combustible dust or a combustible flying
MIT of a dust cloud 8.1 X
MIT of a dust layer 8.2 X
MIE of a dust/air mixture 8.3 X
Tests on resistivity 8.4 X
Measurement of temperature distribution on Annex X
the surface of the hot plate A
Godbert-Greenwald oven Annex X
B
Examples of spark-generating systems Annex X
C
Vertical tube apparatus Annex X
D
20-litre sphere Annex X
E
BAM oven Annex F X
Data for dust explosion characteristics Annex X
G
3
1m vessel Annex X
H
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ISO/IEC 2016
EXPLOSIVE ATMOSPHERES –
Part 20-2: Material characteristics –
Combustible dusts test methods
1 Scope
This part of ISO/IEC 80079 describes the test methods for the identification of combustible
dust and combustible dust layers in order to permit classification of areas where such
materials exist for the purpose of the proper selection and installation of electrical and
mechanical equipment for use in the presence of combustible dust.
The standard atmospheric conditions for determination of characteristics of combustible dusts
are:
• temperature –20 °C to +60 °C,
• pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar) and
• air with normal oxygen content, typically 21 % v/v.
The test methods defined do not apply to:
• recognized explosives, propellants (e.g. gunpowder, dynamite), or substances or mixtures
of substances which may, under some circumstances, behave in a similar manner or
• dusts of explosives and propellants that do not require atmospheric oxygen for
combustion, or to pyrophoric substances.
2 Normative references
None.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
combustible dust
finely divided solid particles, 500 µm or less in nominal size, which may form explosive
mixtures with air at standard atmospheric pressure and temperatures
Note 1 to entry: This includes dust and grit as defined in ISO 4225.
Note 2 to entry: The term 'solid particles' is intended to address particles in the solid phase but does not preclude
a hollow particle.
3.1.1
conductive dust
combustible metal dusts and other combustible dusts with electrical resistivity equal to or less
3
than 1 × 10 Ω⋅m
Note 1 to entry: Metal dust is treated as conductive dust because it is assumed that surface oxidation cannot be
3
depended upon to always ensure electrical resistivity greater than 1 × 10 Ω⋅m
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ISO/IEC 80079-20-2:2016 – 9 –
ISO/IEC 2016
3.1.2
non-conductive dust
3
combustible dust with electrical resistivity greater than 1 × 10 Ω⋅m
3.2
combustible flyings
solid particles, including fibres, where one dimension is greater than 500 µm in nominal size,
which may form an explosive mixture with air at standard atmospheric pressure and
temperature
Note 1 to entry: The ratio of length to width is 3 or more.
Note 2 to entry: Examples of flyings include carbon fibre, rayon, cotton (including cotton linters and cotton waste),
sisal, jute, hemp, cocoa fibre, oakum and baled waste kapok.
3.3
explosive dust atmosphere
mixture with air, under atmospheric conditions, of combustible substances in the form of dust,
fibres, or flyings which, after ignition, permits self-sustaining propagation
3.4
minimum ignition temperature of a dust layer
lowest temperature of a hot surface at which ignition occurs in a dust layer under specified
test conditions
3.5
minimum ignition temperature of a dust cloud
lowest temperature of a hot surface on which the most ignitable mixture of the dust with air is
ignited under specified test conditions
3.6
minimum ignition energy (of a combustible dust/air mixture)
lowest electrical energy stored in a capacitor which upon discharge is sufficient to effect
ignition of the most sensitive dust/air mixture under specified test conditions
4 Dust sample requirements
4.1 Receipt of sample for testing
A material safety data sheet or equivalent with the sample.
The test material shall be provided in suitable packaging, labelled according to relevant
guidelines labelled according to relevant guidelines, and appropriate transportation.
NOTE It is usual to provide a quantity of at least 0,5 kg for testing. If sample preparation is required this may be
insufficient. If only a smaller volume of material is available then the full range of testing may not be possible.
4.2 Characterisation of sample
The sample shall be representative of the material as it appears in the entire process
operated.
NOTE Many unit operations such as extract systems will separate dust into finer fractions than seen in the main
processing equipment and this is accounted for when taking the sample.
If the sample is not representative of the material as found in the process then sample
preparation shall be carried out to apply the worst case conditions.
At least the following information about the sample shall be provided:
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ISO/IEC 2016
– minimum particle size,
– median particle size,
– maxim
...
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