IEC 61340-4-4:2012
(Main)Electrostatics - Part 4-4: Standard test methods for specific applications - Electrostatic classification of flexible intermediate bulk containers (FIBC)
Electrostatics - Part 4-4: Standard test methods for specific applications - Electrostatic classification of flexible intermediate bulk containers (FIBC)
IEC 61340-4-4:2012 specifies requirements for flexible intermediate bulk containers (FIBC) between 0,25 m3 and 3 m3 in volume, intended for use in hazardous explosive atmospheres. The explosive atmosphere may be created by the contents in the FIBC or may exist outside the FIBC. The requirements include:
- classification and labelling of FIBC;
- classification of inner liners;
- specification of test methods for each type of FIBC and inner liner;
- design and performance requirements for FIBC and inner liners;
- safe use of FIBC (including those with inner liners) within different zones defined for explosion endangered environments, described for areas where combustible dusts are, or may be, present (IEC 60079-10-2), and for explosive gas atmospheres (IEC 60079-10-1);
- procedures for type qualification and certification of FIBC, including the safe use of inner liners.
The requirements of this standard are applicable to all types of FIBC and inner liners, tested as manufactured, prior to use and intended for use in hazardous explosive atmospheres: Zones 1 and 2 (Groups IIA and IIB only) and Zones 21 and 22. For some types of FIBC, the requirements of this standard apply only to use in hazardous explosive atmospheres with minimum ignition energy of 0,14 mJ or greater and where charging currents do not exceed 3,0 μA. Compliance with the requirements specified in this standard does not necessarily ensure that hazardous electrostatic discharges, e.g. cone discharges, will not be generated by the contents in FIBC. Compliance with the requirements of this standard does not mitigate the need for full risk assessment. For example, metal and other conductive powders and toner powders may require additional precautions to prevent hazardous discharges from the powders. Test methods included in this standard may be used in association with other performance requirements, for example when a risk assessment has shown the minimum ignition energy of concern is less than 0,14 mJ, charging currents are greater than 3,0 μA, or the ambient conditions are outside of the range specified in this standard. Compliance with the requirements specified in this standard does not necessarily ensure that electric shocks to personnel will not occur from FIBC during normal use. This second edition cancels and replaces the first edition, published in 2005, and constitutes a technical revision. The main changes with respect to the first edition are listed below:
a) Adoption of a type classification system for FIBC based on four types: A, B, C and D.
b) Guidance for safe use of FIBC in relation to hazardous areas and hazardous zones defined in IEC 60079-10-1 and IEC 60079-10-2 is added.
c) Resistance to groundable points and electrical breakdown voltage measurements on FIBC shall be measured at low humidity only.
d) Requirements for labelling FIBC are changed to improve clarity and ease of recognition by end users.
e) Classification, performance requirements and guidance for safe use of inner liners in combination with FIBC are added.
f) An informative annex giving guidance on test methods for quality control and inspection testing is added.
Électrostatique - Partie 4-4: Méthodes d'essai normalisées pour des applications spécifiques - Classification électrostatique des grands récipients pour vrac souples (GRVS)
La CEI 61340-4-4:2012 spécifie les exigences relatives aux grands récipients pour vrac souples (GRVS) dont le volume est compris entre 0,25 m3 et 3 m3, destinés à être utilisés dans des atmosphères explosives dangereuses. L'atmosphère explosive peut être créée par le contenu du GRVS ou peut exister à l'extérieur du GRVS. Les exigences comportent:
- la classification et l'étiquetage des GRVS;
- la classification des revêtements protecteurs intérieurs;
- la spécification des méthodes d'essai pour chaque type de GRVS et de revêtement protecteur intérieur;
- les exigences de conception et de performance des GRVS et des revêtements protecteurs intérieurs;
- l'utilisation sûre des GRVS (incluant ceux qui comportent des revêtements protecteurs intérieurs) dans des zones différentes définies pour des environnements présentant un danger d'explosion, décrite pour des zones où des poussières combustibles sont présentes ou peuvent être présentes (CEI 60079-10-2) et pour des atmosphères explosives gazeuses (CEI 60079-10-1);
- les procédures de qualification de type et de certification des GRVS, incluant l'utilisation sûre des revêtements protecteurs intérieurs.
Les exigences de la présente norme sont applicables à tous les types de GRVS et de revêtements protecteurs intérieurs, testés dans leurs conditions de fabrication, avant utilisation, et destinés à être utilisés dans des atmosphères explosives dangereuses: zones 1 et 2 (Groupes IIA & IIB seulement) et zones 21 & 22. Pour certains types de GRVS, les exigences de la présente norme s'appliquent uniquement à une utilisation dans des atmosphères explosives dangereuses avec une énergie d'allumage minimale de 0,14 mJ ou plus et où les courants de charge ne dépassent pas 3,0 μA. La conformité avec les exigences spécifiées dans la présente norme ne garantit pas nécessairement que des décharges électrostatiques dangereuses, par exemple des décharges de cônes, ne seront pas générées par le contenu des GRVS. La conformité avec les exigences de la présente norme ne réduit pas la nécessité d'une évaluation complète des risques. Par exemple les poudres conductrices et les poudres de toner peuvent nécessiter des précautions supplémentaires pour empêcher des décharges dangereuses des poudres. Les méthodes d'essai comprises dans la présente norme peuvent être utilisées en association avec d'autres exigences de performance; par exemple lorsqu'une évaluation des risques a montré que l'énergie d'allumage minimale concernée est inférieure à 0,14 mJ, que des courants de charge sont supérieurs à 3,0 μA ou que les conditions ambiantes sont à l'extérieur de la plage spécifiée par la présente norme. La conformité avec les exigences spécifiées dans la présente norme ne garantit pas nécessairement que des chocs électriques sur le personnel ne se produiront pas à partir du GRVS au cours d'une utilisation normale. Cette seconde édition annule et remplace la première édition, publiée en 2005, et elle en constitue une révision technique. Les principales modifications par rapport à la première édition sont énumérées ci-dessous:
a) Adoption du système de classification des GRVS basé sur quatre types: A, B, C et D.
b) Des conseils sont ajoutés pour l'utilisation sûre de GRVS par rapport aux secteurs dangereux et des zones dangereuses définies dans la CEI 60079-10-1 et IEC 60079-10-2.
c) La résistance aux points de mise à la terre et des mesures de tension de claquage électrique sur GRVS sera mesurée seulement lors de faible à l'humidité.
d) Les exigences pour étiqueter les GRVS sont changées pour améliorer la clarté et la facilité de reconnaissance par les utilisateurs finaux.
e) La classification, des exigences de performance et des conseils pour l'utilisation sûre de pochettes intérieures en association avec les GRVS sont ajoutés.
f) Une annexe informative donnant des conseils sur des méthodes d'essai pour le contrôle qualité et les essais d'inspection est ajoutée.
General Information
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Standards Content (Sample)
IEC 61340-4-4 ®
Edition 2.0 2012-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrostatics –
Part 4-4: Standard test methods for specific applications – Electrostatic
classification of flexible intermediate bulk containers (FIBC)
Électrostatique –
Partie 4-4: Méthodes d'essai normalisées pour des applications spécifiques –
Classification électrostatique des grands récipients pour vrac souples (GRVS)
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IEC 61340-4-4 ®
Edition 2.0 2012-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrostatics –
Part 4-4: Standard test methods for specific applications – Electrostatic
classification of flexible intermediate bulk containers (FIBC)
Électrostatique –
Partie 4-4: Méthodes d'essai normalisées pour des applications spécifiques –
Classification électrostatique des grands récipients pour vrac souples (GRVS)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 17.220.99; 29.020; 55.080 ISBN 978-2-88912-851-8
– 2 – 61340-4-4 IEC:2012
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 Classification . 10
4.1 Principles of classification for FIBC . 10
4.1.1 Type A . 10
4.1.2 Type B . 10
4.1.3 Type C . 10
4.1.4 Type D . 10
4.2 Principles of classification and requirements for inner liners . 11
4.2.1 Surface resistivity measurements for inner liners . 11
4.2.2 Special cases . 11
4.2.3 Type L1 . 11
4.2.4 Type L2 . 11
4.2.5 Type L3 . 12
4.3 Combination of FIBC and inner liners . 12
5 Safe use of FIBC . 13
6 Labelling . 14
7 Requirements for FIBC . 17
7.1 General remarks. 17
7.2 Requirements for dust environments with ignition energies greater than 3 mJ
(apply to Type B FIBC, Type C FIBC and Type D FIBC) . 17
7.3 Requirements for vapour and gas atmospheres and for dust environments
with ignition energies of 3 mJ or less . 17
7.3.1 Type C FIBC . 17
7.3.2 Type D FIBC . 18
8 Atmosphere for conditioning, calibrating and testing . 18
8.1 Conditioning time . 18
8.2 Electrical breakdown voltage and resistance to groundable point testing . 18
8.3 Ignition testing . 18
9 Test procedures . 18
9.1 Electrical breakdown voltage . 18
9.2 Ignition testing . 19
9.2.1 Apparatus . 19
9.2.2 Establishing correct charging current . 26
9.2.3 Ignition tests . 26
9.3 Resistance to groundable point . 28
9.3.1 Apparatus . 28
9.3.2 Test procedure . 29
10 Report . 30
10.1 For all types of testing . 30
10.2 For electrical breakdown voltage testing . 31
10.3 For ignition testing . 31
61340-4-4 IEC:2012 – 3 –
10.4 For resistance to groundable point testing . 31
10.5 For surface resistivity testing of inner liners . 31
10.6 For test reports issued by accredited testing authorities . 31
Annex A (normative) Electrical breakdown voltage – Typical voltage/time graphs . 33
Annex B (normative) Polypropylene pellets for ignition testing . 34
Annex C (informative) Guidance on test methods for manufacturing quality control . 35
Annex D (normative) Classification of hazardous areas and zones. 37
Annex E (informative) Risks associated with cone discharges . 38
Annex F (informative) Explanation for resistance and resistivity limits . 39
Bibliography . 40
Figure 1 – Example of a label for Type B FIBC . 15
Figure 2 – Example of a label for Type C FIBC . 15
Figure 3 – Example of a label for Type D FIBC . 16
Figure 4 – Example of a label for Type C FIBC designated earth bonding points . 16
Figure 5 – Ignition probe . 20
Figure 6 – Perforated metal plate for use in ignition probe . 21
Figure 7 – Gas control and mixing apparatus (schematic) . 22
Figure 8 – FIBC filling rig (schematic) . 24
Figure 9 – Corona charging unit (schematic) . 25
Figure A.1 – Example of voltage/time graph for material showing distinct breakdown . 33
Figure A.2 – Example of voltage/time graph for material showing reduction in rate of
voltage rise because of conduction within the test material . 33
Table 1 – Permissible configurations and requirements for Type L1 inner liners . 11
Table 2 – Permissible configurations and requirements for Type L2 inner liners . 12
Table 3 – Permissible configurations and requirements for Type L3 inner liners . 12
Table 4 – Use of different types of FIBC . 13
Table 5 – Inner liners and FIBC: combinations that are permissible and not permissible
in hazardous explosive atmospheres . 13
Table 6 – Volume concentrations of flammable gas mixture . 21
Table 7 – Example of full sample description to be included in test report . 32
Table B.1 – Particle size distribution of polypropylene pellets . 34
Table D.1 – Classification of hazardous areas in IEC 60079-10-1 and IEC 60079-10-2 . 37
Table D.2 – Classification of zones in IEC 60079-10-1 and IEC 60079-10-2 . 37
– 4 – 61340-4-4 IEC:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROSTATICS –
Part 4-4: Standard test methods for specific applications –
Electrostatic classification of flexible intermediate bulk containers (FIBC)
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61340-4-4 has been prepared by IEC technical committee 101:
Electrostatics, in cooperation with ISO subcommittee 3: Performance requirements and tests
for means of packaging, packages and unit loads, of ISO technical committee 122: Packaging.
This second edition cancels and replaces the first edition, published in 2005, and constitutes
a technical revision.
The main changes with respect to the first edition are listed below:
a) Adoption of a type classification system for FIBC based on four types: A, B, C and D.
b) Guidance for safe use of FIBC in relation to hazardous areas and hazardous zones
defined in IEC 60079-10-1 and IEC 60079-10-2 is added.
c) Resistance to groundable points and electrical breakdown voltage measurements on FIBC
shall be measured at low humidity only.
61340-4-4 IEC:2012 – 5 –
d) Requirements for labelling FIBC are changed to improve clarity and ease of recognition by
end users.
e) Classification, performance requirements and guidance for safe use of inner liners in
combination with FIBC are added.
f) An informative annex giving guidance on test methods for quality control and inspection
testing is added.
The text of this standard is based on the following documents:
FDIS Report on voting
101/346/FDIS 101/353/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61340 series, published under the general title Electrostatics,
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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – 61340-4-4 IEC:2012
INTRODUCTION
Flexible intermediate bulk containers (FIBC) are widely used for the storage, transportation
and handling of powdered, flaked or granular material. Typically, they are constructed from
woven polypropylene fabric in the form of cubic bags of about 1 m volume, although they can
3 3
vary in shape and in size from 0,25 m to 3 m . The fabric used may be a single layer, a
multi-layer laminate, or a coated fabric. Untreated polypropylene is an electrical insulator, as
is often the case with the products placed in FIBC. There is ample opportunity for the
generation of electrostatic charge during filling and emptying operations and in unprotected
FIBC high levels of charge can quickly build up. In such cases, electrostatic discharges are
inevitable and can be a severe problem when FIBC are used in hazardous explosive
atmospheres.
A hazardous explosive atmosphere can be generated when handling fine powders that create
dust clouds or thin layers of powder, both of which can be ignited by electrostatic discharges.
A hazardous explosive atmosphere can also be generated when using gases or volatile
solvents. In these industrial situations there is clearly a need to eliminate incendive
electrostatic discharges.
As with any industrial equipment, a thorough risk assessment should always be conducted
before using FIBC in potentially hazardous situations. This part of IEC 61340 describes a
system of classification, test methods, performance and design requirements and safe use
procedures that can be used by manufacturers, specifiers and end-users as part of a risk
assessment of any FIBC intended for use within a hazardous explosive atmosphere. However,
it does not include procedures for evaluating the specific risks of electrostatic discharges
arising from products within FIBC, e.g. cone discharges, from personnel or from equipment
used near FIBC. Information on risks associated with cone discharges is given in Annex E.
CAUTION: The test methods specified in this standard involve the use of high voltage power
supplies and flammable gases that may present hazards if handled incorrectly, particularly by
unqualified or inexperienced personnel. Users of this standard are encouraged to carry out
proper risk assessments and pay due regard to local regulations before undertaking any of
the test procedures.
61340-4-4 IEC:2012 – 7 –
ELECTROSTATICS –
Part 4-4: Standard test methods for specific applications –
Electrostatic classification of flexible intermediate bulk containers (FIBC)
1 Scope
This part of IEC 61340 specifies requirements for flexible intermediate bulk containers (FIBC)
3 3
between 0,25 m and 3 m in volume, intended for use in hazardous explosive atmospheres.
The explosive atmosphere may be created by the contents in the FIBC or may exist outside
the FIBC.
The requirements include:
− classification and labelling of FIBC;
− classification of inner liners;
− specification of test methods for each type of FIBC and inner liner;
− design and performance requirements for FIBC and inner liners;
− safe use of FIBC (including those with inner liners) within different zones defined for
explosion endangered environments, described for areas where combustible dusts are, or
may be, present (IEC 60079-10-2), and for explosive gas atmospheres (IEC 60079-10-1);
− procedures for type qualification and certification of FIBC, including the safe use of inner
liners.
NOTE 1 Guidance on test methods that may be used for manufacturing quality control is given in Annex C.
The requirements of this standard are applicable to all types of FIBC and inner liners, tested
as manufactured, prior to use and intended for use in hazardous explosive atmospheres:
Zones 1 and 2 (Groups IIA and IIB only) and Zones 21 and 22 (see Annex D for classification
of hazardous areas and explosion groups). For some types of FIBC, the requirements of this
standard apply only to use in hazardous explosive atmospheres with minimum ignition energy
of 0,14 mJ or greater and where charging currents do not exceed 3,0 µA.
NOTE 2 0,14 mJ is the minimum ignition energy of a typical Group IIB gas or vapour. Although more sensitive
materials exist, 0,14 mJ is the lowest minimum ignition energy of any material that is likely to be present when
FIBC are emptied. 3,0 µA is the highest charging current likely to be found in common industrial processes. This
combination of minimum ignition energy and charging current represents the most severe conditions that might be
expected in practice.
Compliance with the requirements specified in this standard does not necessarily ensure that
hazardous electrostatic discharges, e.g. cone discharges, will not be generated by the
contents in FIBC. Information on the risks associated with cone discharges is given in Annex
E.
Compliance with the requirements of this standard does not mitigate the need for full risk
assessment. For example, metal and other conductive powders and toner powders may
require additional precautions to prevent hazardous discharges from the powders.
NOTE 3 In the examples mentioned in the paragraph above, additional precautions may be necessary in the case
of metal or other conductive powder because if the powder is isolated and becomes charged, incendiary sparks
may occur, and in the case of toner powders, incendiary discharges may occur during rapid filling and emptying
operations. Future IEC/TS 60079-32 [1] gives guidance on additional precautions that may be necessary.
———————
Figures in square brackets refer to the bibliography.
– 8 – 61340-4-4 IEC:2012
Test methods included in this standard may be used in association with other performance
requirements, for example when a risk assessment has shown the minimum ignition energy of
concern is less than 0,14 mJ, charging currents are greater than 3,0 µA, or the ambient
conditions are outside of the range specified in this standard.
Compliance with the requirements specified in this standard does not necessarily ensure that
electric shocks to personnel will not occur from FIBC during normal use.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60079-10-1, Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas
atmospheres
IEC 60079-10-2, Explosive atmospheres – Part 10-2: Classification of areas – Combustible
dust atmospheres
IEC 60243-1:1998, Electric strength of insulating materials – Test methods – Part 1: Tests at
power frequencies
IEC 60243-2, Electric strength of insulating materials – Test methods – Part 2: Additional
requirements for tests using direct voltage
IEC 60417-5019:2006, Graphical symbols for use on equipment. Available at:
symbols.info/equipment>"
IEC 61241-2-3, Electrical apparatus for use in the presence of combustible dust – Part 2: Test
methods – Section 3: Method for determining minimum ignition energy of dust/air mixtures
IEC 61340-2-3, Electrostatics – Part 2-3: Methods of test for determining the resistance and
resistivity of solid planar materials used to avoid electrostatic charge accumulation
ISO 7000:2004, Graphical symbols for use on equipment – Index and synopsis
ISO 21898, Packaging – Flexible intermediate bulk containers (FIBCs) for non-dangerous
goods
ASTM E582, Standard test method for minimum ignition energy and quenching distance in
gaseous mixtures
3 Terms and definitions
For the purposes of this document, the following terms and definitions, as well as those given
in IEC 60079-10-1, IEC 60079-10-2 and ISO 21898, apply.
3.1
quenching
effect of solid objects acting as heat sinks in close proximity to gas
3.2
critical quenching distance
maximum separation distance between opposing electrodes below which quenching prevents
ignition at a specified energy
61340-4-4 IEC:2012 – 9 –
NOTE For ignitions to take place, the gap between electrodes should be greater than the critical quenching
distance.
3.3
flammable substance
substance in the form of gas, vapour, liquid, solid, or mixture of these, capable of propagating
combustion when subjected to an ignition source
3.4
explosive atmosphere
mixture with air, under atmospheric conditions, of flammable substances in the form of gases,
vapours, mists or dusts in which, after ignition has occurred, combustion spreads to the entire
unburned mixture
3.5
hazardous explosive atmosphere
explosive atmosphere present in such quantities that precautions against ignition are required
3.6
minimum ignition energy
least electrical energy of a purely capacitive spark (i.e. no added inductance) required to
ignite a dust, gas or vapour
3.7
charging current
quantity of charge per unit time flowing into FIBC
3.8
cone discharge
electrostatic discharge running outwards across the surface from the top of highly charged,
insulating powder heaps in large containers
3.9
brush discharge
electrostatic discharge from a non-conductive, solid or liquid surface
3.10
spark
electrostatic discharge from an electrically isolated conductive object or surface
3.11
propagating brush discharge
highly energetic discharge from an insulating sheet, layer or coating on a conductive surface,
or a material of high resistivity and high break down voltage with the two surfaces highly
charged to opposite polarity
3.12
inner liner
integral or removable container which fits into the FIBC (synonymous with liner)
3.13
surface resistivity
equivalent to the surface resistance of a square area of material, having electrodes at two
opposite sides
3.14
volume resistivity
equivalent to the volume resistance of a cube of material with unit length, having the
electrodes at two opposite surfaces
– 10 – 61340-4-4 IEC:2012
3.15
type qualification testing
testing used to determine the type of FIBC as specified in 4.1 and to demonstrate that FIBC
meet the requirements of Clause 7
3.16
quality control testing
testing designed to provide manufacturers and users with information that demonstrates all
FIBC produced and delivered are substantially the same as the sample FIBC used to qualify
the FIBC design
3.17
groundable point
point on FIBC designated by the manufacturer as a location to attach a grounding or earth
bonding cable or other means of earthing FIBC
NOTE There may be one or more groundable points on each FIBC. Lift loops may also be designated as
groundable points, but fortuitous earthing via lifting hooks should not be relied as these may be painted/coated, or
covered with powder etc., and so may not guarantee an adequate earth path.
4 Classification
4.1 Principles of classification for FIBC
FIBC are classified according to one of four types: Type A, Type B, Type C and Type D. The
types are defined by the construction of the FIBC, the nature of their intended operation and
associated performance requirements.
An individual design of FIBC may only be classified as one single type; for example one FIBC
cannot be simultaneously classified as both Type B and Type D, or as Type CD.
4.1.1 Type A
Type A FIBC are made from fabric or plastic sheet without any measures against the build up
of static electricity. Any FIBC that does not meet the requirements specified in Clause 7, or
which has not been tested against the requirements is classified as Type A.
4.1.2 Type B
Type B FIBC are made from fabric or plastic sheet designed to prevent the occurrence of
sparks and propagating brush discharges.
4.1.3 Type C
Type C FIBC are made from conductive fabric or plastic sheet, or interwoven with conductive
threads or filaments and designed to prevent the occurrence of incendiary sparks, brush
discharges and propagating brush discharges. Type C FIBC are designed to be connected to
earth during filling and emptying operations.
4.1.4 Type D
Type D FIBC are made from static protective fabric designed to prevent the occurrence of
incendiary sparks, brush discharges and propagating brush discharges, without the need for a
connection from the FIBC to earth.
61340-4-4 IEC:2012 – 11 –
4.2 Principles of classification and requirements for inner liners
4.2.1 Surface resistivity measurements for inner liners
Surface resistivity shall be measured according to IEC 61340-2-3. A minimum of ten
measurements shall be made at points evenly distributed over the inner liner surface. All
measurements shall be within the limits specified for the type of inner liner being tested.
4.2.2 Special cases
Inner liners made from materials that contain a conductive layer sandwiched between two
insulating layers shall not be used in Type B or Type D FIBC. If such an inner liner is used in
Type C FIBC, the conductive layer shall be securely bonded to earth. The thickness of the
insulating layers shall be less than 700 µm, and the breakdown voltage measured between an
electrode placed on each surface in turn and the conductive layer shall be less than 4 kV,
measured according to 9.1 under the conditions specified in 8.2.
NOTE In order to avoid incendiary brush discharge, the thickness of any exposed insulating layers in contact with
non-insulating layers is limited to a maximum of 700 µm.
4.2.3 Type L1
Type L1 inner liners are made from materials with surface resistivity on at least one surface
Ω (see Annex F), measured under the conditions specified in
less than or equal to 1,0 × 10
8.2. of this standard. Type L1 inner liners may be used in Type C FIBC.
If the material is multi-layered, or if the material has one surface with surface resistivity
greater than 1,0 × 10 Ω, the breakdown voltage through the material shall be less than 4 kV,
measured according to 9.1 under the conditions specified in 8.2.
The thickness of any layer with surface resistivity greater than 1,0 × 10 Ω on the inside
(product side) of the inner liner material shall be less than 700 µm.
Permissible configurations and requirements for type L1 inner liners are summarized in
Table 1.
Table 1 – Permissible configurations and requirements for Type L1 inner liners
Parameters
Resistivity of Resistivity of
Configuration
Breakdown voltage Thickness
inside surface outside surface
V d
B
ρ ρ
I O
7 7
ρ ≤ 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω No measurement required No limit
I O
7 12
2A No measurement required No limit
ρ ≤ 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω
I O
12 7
2B No measurement required No limit
ρ ≤ 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω
I O
7 12
3 V < 4 kV No limit
ρ ≤ 1,0 × 10 Ω ρ > 1,0 × 10 Ω
B
I O
12 7
4 ρ > 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω V < 4 kV d <700 µm
I O B
4.2.4 Type L2
Type L2 inner liners are made from materials with surface resistivity on at least one surface
9 12
between 1,0 × 10 Ω and 1,0 × 10 Ω (see Annex F), measured under the conditions
specified in 8.3. Type L2 inner liners may be used in Type B, Type C and Type D FIBC.
– 12 – 61340-4-4 IEC:2012
If Type L2 inner liners are used in Type C FIBC, the charging current shall not exceed 3 µA.
If the material is multi-layered, or if the material has one surface with surface resistivity
Ω, the breakdown voltage through the material shall be less than 4 kV,
greater than 1,0 × 10
measured according to 9.1 under the conditions specified in 8.2.
The thickness of any layer with surface resistivity greater than 1,0 × 10 Ω on the inside
(product side) of the inner liner material shall be less than 700 µm.
Permissible configurations and requirements for Type L2 inner liners are summarized in
Table 2.
Table 2 – Permissible configurations and requirements for Type L2 inner liners
Parameters
Resistivity of Resistivity of Breakdown
Configuration
Thickness
inside surface outside surface voltage
d
ρ ρ V
I O B
No
9 12 9 12
1 1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω 1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω measurement No limit
I O
required
9 12 12
2 V < 4 kV No limit
1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω ρ > 1,0 × 10 Ω
B
I O
12 9 12
3 V < 4 kV d <700 µm
ρ > 1,0 × 10 Ω 1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω
B
I I
4.2.5 Type L3
Type L3 inner liners are made from materials with surface resistivity of greater than
1,0 × 10 Ω, measured under the conditions specified in 8.2. Type L3 inner liners may be
used in Type B FIBC.
The breakdown voltage through the material shall be less than 4 kV, measured according to
9.1 under the conditions specified in 8.2.
Permissible configurations and requirements for Type L3 inner liners are summarized in
Table 3.
Table 3 – Permissible configurations and requirements for Type L3 inner liners
Parameters
Resistivity of Resistivity of Breakdown
Configuration
Thickness
inside surface outside surface voltage
d
ρ ρ V
I O B
12 12
1 V < 4 kV No limit
ρ > 1,0 × 10 Ω ρ > 1,0 × 10 Ω
B
I O
4.3 Combination of FIBC and inner liners
The inclusion of an inner liner in FIBC does not change the type classification of the FIBC.
For example, Type A FIBC with Type L1 inner liners are still Type A FIBC and are subject to
all the restrictions on use of Type A FIBC.
The requirements for breakdown voltage for FIBC and inner liners shall be applied separately.
For Type B, Type C and Type D FIBC with inner liners for which there is a breakdown voltage
requirement, two sets of breakdown voltage measurement shall be required: one set on the
FIBC material and one set on the inner liner material. For example, if a Type B FIBC is fitted
61340-4-4 IEC:2012 – 13 –
with a Type L3 inner liner, the breakdown voltage of the FIBC material shall be measured on
its own and shall be less than 6 kV and a separate breakdown voltage measurement shall be
made on the inner liner material and it shall be less than 4 kV.
5 Safe use of FIBC
The requirements and specifications that FIBC must meet and the ways in which they are
used depend on the nature and sensitivity of any explosive atmosphere present during filling
and emptying. The final goal for the construction of FIBC is to exclude incendiary discharges
from the FIBC fabric during their intended use. FIBC constructed in compliance with the
requirements specified in this standard do not necessarily ensure that hazardous electrostatic
discharges, e.g. cone discharges, will not be generated by the contents in FIBC. Information
on the risks associated with cone discharges is given in Annex E.
The igniting ability of electrostatic discharges, i.e. sparks, brush discharges and propagating
brush discharges, is different for each type of discharge. The necessity of their exclusion and
thus the requirements and specifications for FIBC depend on the intended use of the FIBC.
The conditions in which each type of FIBC shall be used is shown in Table 4.
Table 4 – Use of different types of FIBC
Bulk product in FIBC Surroundings
b
Gas zones 1-2
b
(Explosion groups IIA/IIB)
b
Non-flammable Dust zones 21-22
a
MIE of dust or
a
atmosphere
(1 000 mJ ≥ MIE > 3 mJ) b
dust zones 21-22
a
(MIE ≤ 3 mJ)
c
A,B,C,D B,C,D C,D
MIE > 1 000 mJ
c
1 000 mJ ≥ MIE > 3 mJ B,C,D B,C,D C,D
c
d
C,D C,D C,D
MIE ≤ 3 mJ
NOTE 1 Additional precautions are usually necessary when a flammable gas or vapour atmosphere is present
inside the FIBC, e.g. in the case of solvent wet powders.
NOTE 2 Non-flammable atmosphere includes dusts having a MIE > 1 000 mJ.
a
Measured in accordance with IEC 61241-2-3, capacitive discharge circuit (no added inductance).
b
See Annex D for explanation of hazardous areas, zones and explosion groups.
c
Use of Type D shall be limited to explosion groups IIA/IIB with MIE ≥ 0,14 mJ.
d
See Annex E for explanation of the 3 mJ limit in relation to cone discharges.
The ability to safely use FIBC in hazardous explosive atmospheres may change if an inner
liner is installed in the FIBC. Combinations of FIBC and inner liner that can be used safely in
hazardous explosive atmospheres are shown in Table 5. In addition to the separate
requirements for FIBC and inner liners, there are requirements that certain combinations of
FIBC and inner liner shall meet. These requirements are also shown in Table 5.
Table 5 – Inner liners and FIBC: combinations that are permissible
and not permissible in hazardous explosive atmospheres
Inner liner
FIBC
Type L1 Type L2 Type L3
Type B Not permissible Permissible Permissible
a
Type C Permissible Permissible Not permissible
b
Type D Not permissible Permissible Not permissible
– 14 – 61340-4-4 IEC:2012
a
To ensure the inner liner is properly earthed, the resistance from at least one side of the inner liner to the
groundable points on the FIBC shall be less than 1,0 × 10 Ω, measured according to 9.3 under the conditions
specified in 8.2.
b
Combination of FIBC and liner shall meet the requirements of 7.3.2 tested under the conditions specified in 8.3.
Additional precautions:
Type A FIBC shall not be used in hazardous explosive atmospheres, irrespective of the type of liner used.
Liners shall not be removed from emptied FIBC in hazardous explosive atmospheres.
Isolated conductive objects (e.g. tools, bolts, clips, etc.) should not be stored on, attached to,
or even temporarily placed on any type of FIBC during filling and emptying operations. Even
with Type C FIBC, the rough nature of some FIBC materials may prevent conductive objects
placed on the FIBC from contacting the conductive elements in the fabric of the FIBC.
In accordance with general safety guidance (see future IEC/TS 60079-32), all conductive
objects within a hazardous explosive atmosphere shall be properly earthed.
Precautions should be taken to prevent the contamination of any FIBC with substances (e.g.
water, rust, oil, grease, etc.) that might create an ignition hazard or impair charge dissipation.
6 Labelling
FIBC for which claims of compliance with this standard are made, shall be durably marked by
means of a permanently attached label, or other means, with at least the following
information:
a) the number of this standard, i.e. IEC 61340-4-4;
b) the type of FIBC, i.e. Type B, Type C or Type D (the type designation shall be emphasized
so that it is easily readable at a glance);
NOTE Type A FIBC are not required to be labelled.
c) the symbol ISO 7000-2415 (2004-01) on Type B, Type C and Type D to indicate protection
from static electricity;
d) for Type B, the phrase “permitted in dust zone 21-22 with MIE > 3 mJ”;
e) for Type C, the phrase “permitted in dust zones 21-22 and gas zones 1-2 (explosion
groups IIA/IIB)”
f) for Type D the phrase “permitted in dust zones 21-22 and gas zones 1-2 (explosion
groups IIA/IIB with MIE ≥ 0,14 mJ) and where charging currents ≤ 3 µA”,
g) for Type C the phrase “FIBC shall be properly earthed according to manufacturer’s
...
IEC 61340-4-4 ®
Edition 2.1 2014-11
CONSOLIDATED
VERSION
VERSION
CONSOLIDÉE
colour
inside
Electrostatics –
Part 4-4: Standard test methods for specific applications – Electrostatic
classification of flexible intermediate bulk containers (FIBC)
Électrostatique –
Partie 4-4: Méthodes d'essai normalisées pour des applications spécifiques –
Classification électrostatique des grands récipients pour vrac souples (GRVS)
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IEC 61340-4-4 ®
Edition 2.1 2014-11
CONSOLIDATED
VERSION
VERSION
CONSOLIDÉE
colour
inside
Electrostatics –
Part 4-4: Standard test methods for specific applications – Electrostatic
classification of flexible intermediate bulk containers (FIBC)
Électrostatique –
Partie 4-4: Méthodes d'essai normalisées pour des applications spécifiques –
Classification électrostatique des grands récipients pour vrac souples (GRVS)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.99; 29.020; 55.080 ISBN 978-2-8322-1927-0
IEC 61340-4-4 ®
Edition 2.1 2014-11
REDLINE VERSION
VERSION REDLINE
colour
inside
Electrostatics –
Part 4-4: Standard test methods for specific applications – Electrostatic
classification of flexible intermediate bulk containers (FIBC)
Électrostatique –
Partie 4-4: Méthodes d'essai normalisées pour des applications spécifiques –
Classification électrostatique des grands récipients pour vrac souples (GRVS)
– 2 – IEC 61340-4-4:2012
+AMD1:2014 CSV IEC 2014
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 Classification . 10
4.1 Principles of classification for FIBC . 10
4.1.1 Type A . 10
4.1.2 Type B . 10
4.1.3 Type C . 10
4.1.4 Type D . 10
4.2 Principles of classification and requirements for inner liners . 11
4.2.1 Surface resistivity measurements for inner liners . 11
4.2.2 Special cases . 11
4.2.3 Type L1 . 11
4.2.4 Type L2 . 11
4.2.5 Type L3 . 12
4.3 Combination of FIBC and inner liners . 12
5 Safe use of FIBC . 13
6 Labelling . 14
7 Requirements for FIBC . 18
7.1 General remarks. 18
7.2 Requirements for dust environments with ignition energies greater than 3 mJ
(apply to Type B FIBC, Type C FIBC and Type D FIBC) . 19
7.3 Requirements for vapour and gas atmospheres and for dust environments
with ignition energies of 3 mJ or less . 19
7.3.1 Type C FIBC . 19
7.3.2 Type D FIBC . 19
8 Atmosphere for conditioning, calibrating and testing . 20
8.1 Conditioning time . 20
8.2 Electrical breakdown voltage and resistance to groundable point testing . 20
8.3 Ignition testing . 20
9 Test procedures . 20
9.1 Electrical breakdown voltage . 20
9.2 Ignition testing . 20
9.2.1 Apparatus . 20
9.2.2 Establishing correct charging current . 28
9.2.3 Ignition tests . 28
9.3 Resistance to groundable point . 30
9.3.1 Apparatus . 30
9.3.2 Test procedure . 31
10 Report . 32
10.1 For all types of testing . 32
10.2 For electrical breakdown voltage testing . 33
10.3 For ignition testing . 33
+AMD1:2014 CSV IEC 2014
10.4 For resistance to groundable point testing . 33
10.5 For surface resistivity testing of inner liners . 33
10.6 For test reports issued by accredited testing authorities . 33
Annex A (normative) Electrical breakdown voltage – Typical voltage/time graphs . 35
Annex B (normative) Polypropylene pellets for ignition testing . 36
Annex C (informative) Guidance on test methods for manufacturing quality control . 37
Annex D (normative) Classification of hazardous areas and zones. 39
Annex E (informative) Risks associated with cone discharges . 40
Annex F (informative) Explanation for resistance and resistivity limits . 41
Bibliography . 42
Figure 1 – Example of a label for Type B FIBC . 15
Figure 2 – Example of a label for Type C FIBC . 16
Figure 3 – Example of a label for Type D FIBC . 17
Figure 4 – Example of a label for Type C FIBC designated earth bonding points . 18
Figure 5 – Ignition probe . 22
Figure 6 – Perforated metal plate for use in ignition probe . 23
Figure 7 – Gas control and mixing apparatus (schematic) . 24
Figure 8 – FIBC filling rig (schematic) . 26
Figure 9 – Corona charging unit (schematic) . 27
Figure A.1 – Example of voltage/time graph for material showing distinct breakdown . 35
Figure A.2 – Example of voltage/time graph for material showing reduction in rate of
voltage rise because of conduction within the test material . 35
Table 1 – Permissible configurations and requirements for Type L1 inner liners . 11
Table 2 – Permissible configurations and requirements for Type L2 inner liners . 12
Table 3 – Permissible configurations and requirements for Type L3 inner liners . 12
Table 4 – Use of different types of FIBC . 13
Table 5 – Inner liners and FIBC: combinations that are permissible and not permissible
in hazardous explosive atmospheres . 13
Table 6 – Volume concentrations of flammable gas mixture . 23
Table 7 – Example of full sample description to be included in test report . 34
Table B.1 – Particle size distribution of polypropylene pellets . 36
Table D.1 – Classification of hazardous areas in IEC 60079-10-1 and IEC 60079-10-2 . 39
Table D.2 – Classification of zones in IEC 60079-10-1 and IEC 60079-10-2 . 39
– 4 – IEC 61340-4-4:2012
+AMD1:2014 CSV IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROSTATICS –
Part 4-4: Standard test methods for specific applications –
Electrostatic classification of flexible intermediate bulk containers (FIBC)
FOREWORD
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This Consolidated version of IEC 61340-4-4 bears the edition number 2.1. It consists of
the second edition (2012-01) [documents 101/346/FDIS and 101/353/RVD] and its
amendment 1 (2014-11) [documents 101/421/CDV and 101/447/RVC]. The technical
content is identical to the base edition and its amendment.
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions and deletions are displayed in red, with
deletions being struck through. A separate Final version with all changes accepted is
available in this publication.
This publication has been prepared for user convenience.
+AMD1:2014 CSV IEC 2014
International Standard IEC 61340-4-4 has been prepared by IEC technical committee 101:
Electrostatics, in cooperation with ISO subcommittee 3: Performance requirements and tests
for means of packaging, packages and unit loads, of ISO technical committee 122: Packaging.
The main changes with respect to the first edition of this standrad are listed below:
a) Adoption of a type classification system for FIBC based on four types: A, B, C and D.
b) Guidance for safe use of FIBC in relation to hazardous areas and hazardous zones
defined in IEC 60079-10-1 and IEC 60079-10-2 is added.
c) Resistance to groundable points and electrical breakdown voltage measurements on FIBC
shall be measured at low humidity only.
d) Requirements for labelling FIBC are changed to improve clarity and ease of recognition by
end users.
e) Classification, performance requirements and guidance for safe use of inner liners in
combination with FIBC are added.
f) An informative annex giving guidance on test methods for quality control and inspection
testing is added.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61340 series, published under the general title Electrostatics,
can be found on the IEC website.
The committee has decided that the contents of the base publication and its amendment 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC 61340-4-4:2012
+AMD1:2014 CSV IEC 2014
INTRODUCTION
Flexible intermediate bulk containers (FIBC) are widely used for the storage, transportation
and handling of powdered, flaked or granular material. Typically, they are constructed from
woven polypropylene fabric in the form of cubic bags of about 1 m volume, although they can
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vary in shape and in size from 0,25 m to 3 m . The fabric used may be a single layer, a
multi-layer laminate, or a coated fabric. Untreated polypropylene is an electrical insulator, as
is often the case with the products placed in FIBC. There is ample opportunity for the
generation of electrostatic charge during filling and emptying operations and in unprotected
FIBC high levels of charge can quickly build up. In such cases, electrostatic discharges are
inevitable and can be a severe problem when FIBC are used in hazardous explosive
atmospheres.
A hazardous explosive atmosphere can be generated when handling fine powders that create
dust clouds or thin layers of powder, both of which can be ignited by electrostatic discharges.
A hazardous explosive atmosphere can also be generated when using gases or volatile
solvents. In these industrial situations there is clearly a need to eliminate incendive
electrostatic discharges.
As with any industrial equipment, a thorough risk assessment should always be conducted
before using FIBC in potentially hazardous situations. This part of IEC 61340 describes a
system of classification, test methods, performance and design requirements and safe use
procedures that can be used by manufacturers, specifiers and end-users as part of a risk
assessment of any FIBC intended for use within a hazardous explosive atmosphere. However,
it does not include procedures for evaluating the specific risks of electrostatic discharges
arising from products within FIBC, e.g. cone discharges, from personnel or from equipment
used near FIBC. Information on risks associated with cone discharges is given in Annex E.
CAUTION: The test methods specified in this standard involve the use of high voltage power
supplies and flammable gases that may present hazards if handled incorrectly, particularly by
unqualified or inexperienced personnel. Users of this standard are encouraged to carry out
proper risk assessments and pay due regard to local regulations before undertaking any of
the test procedures.
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ELECTROSTATICS –
Part 4-4: Standard test methods for specific applications –
Electrostatic classification of flexible intermediate bulk containers (FIBC)
1 Scope
This part of IEC 61340 specifies requirements for flexible intermediate bulk containers (FIBC)
3 3
between 0,25 m and 3 m in volume, intended for use in hazardous explosive atmospheres.
The explosive atmosphere may be created by the contents in the FIBC or may exist outside
the FIBC.
The requirements include:
− classification and labelling of FIBC;
− classification of inner liners;
− specification of test methods for each type of FIBC and inner liner;
− design and performance requirements for FIBC and inner liners;
− safe use of FIBC (including those with inner liners) within different zones defined for
explosion endangered environments, described for areas where combustible dusts are, or
may be, present (IEC 60079-10-2), and for explosive gas atmospheres (IEC 60079-10-1);
− procedures for type qualification and certification of FIBC, including the safe use of inner
liners.
NOTE 1 Guidance on test methods that may be used for manufacturing quality control is given in Annex C.
The requirements of this standard are applicable to all types of FIBC and inner liners, tested
as manufactured, prior to use and intended for use in hazardous explosive atmospheres:
Zones 1 and 2 (Groups IIA and IIB only) and Zones 21 and 22 (see Annex D for classification
of hazardous areas and explosion groups). For some types of FIBC, the requirements of this
standard apply only to use in hazardous explosive atmospheres with minimum ignition energy
of 0,14 mJ or greater and where charging currents do not exceed 3,0 µA.
NOTE 2 0,14 mJ is the minimum ignition energy of a typical Group IIB gas or vapour. Although more sensitive
materials exist, 0,14 mJ is the lowest minimum ignition energy of any material that is likely to be present when
FIBC are emptied. 3,0 µA is the highest charging current likely to be found in common industrial processes. This
combination of minimum ignition energy and charging current represents the most severe conditions that might be
expected in practice.
Compliance with the requirements specified in this standard does not necessarily ensure that
hazardous electrostatic discharges, e.g. cone discharges, will not be generated by the
contents in FIBC. Information on the risks associated with cone discharges is given in
Annex E.
Compliance with the requirements of this standard does not mitigate the need for full risk
assessment. For example, metal and other conductive powders and toner powders may
require additional precautions to prevent hazardous discharges from the powders.
NOTE 3 In the examples mentioned in the paragraph above, additional precautions may be necessary in the case
of metal or other conductive powder because if the powder is isolated and becomes charged, incendiary sparks
may occur, and in the case of toner powders, incendiary discharges may occur during rapid filling and emptying
operations. Future IEC TS 60079-32-1 [1] gives guidance on additional precautions that may be necessary.
———————
Figures in square brackets refer to the bibliography.
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Test methods included in this standard may be used in association with other performance
requirements, for example when a risk assessment has shown the minimum ignition energy of
concern is less than 0,14 mJ, charging currents are greater than 3,0 µA, or the ambient
conditions are outside of the range specified in this standard.
Compliance with the requirements specified in this standard does not necessarily ensure that
electric shocks to personnel will not occur from FIBC during normal use.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60079-10-1, Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas
atmospheres
IEC 60079-10-2, Explosive atmospheres – Part 10-2: Classification of areas – Combustible
dust atmospheres
IEC 60243-1:1998, Electric strength of insulating materials – Test methods – Part 1: Tests at
power frequencies
IEC 60243-2, Electric strength of insulating materials – Test methods – Part 2: Additional
requirements for tests using direct voltage
IEC 60417-5019:2006, Graphical symbols for use on equipment. Available at:
symbols.info/equipment>"
IEC 61241-2-3, Electrical apparatus for use in the presence of combustible dust – Part 2: Test
methods – Section 3: Method for determining minimum ignition energy of dust/air mixtures
IEC 61340-2-3, Electrostatics – Part 2-3: Methods of test for determining the resistance and
resistivity of solid planar materials used to avoid electrostatic charge accumulation
ISO 7000:2004, Graphical symbols for use on equipment – Index and synopsis
ISO 21898, Packaging – Flexible intermediate bulk containers (FIBCs) for non-dangerous
goods
ASTM E582, Standard test method for minimum ignition energy and quenching distance in
gaseous mixtures
3 Terms and definitions
For the purposes of this document, the following terms and definitions, as well as those given
in IEC 60079-10-1, IEC 60079-10-2 and ISO 21898, apply.
3.1
quenching
effect of solid objects acting as heat sinks in close proximity to gas
3.2
critical quenching distance
maximum separation distance between opposing electrodes below which quenching prevents
ignition at a specified energy
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NOTE For ignitions to take place, the gap between electrodes should be greater than the critical quenching
distance.
3.3
flammable substance
substance in the form of gas, vapour, liquid, solid, or mixture of these, capable of propagating
combustion when subjected to an ignition source
3.4
explosive atmosphere
mixture with air, under atmospheric conditions, of flammable substances in the form of gases,
vapours, mists or dusts in which, after ignition has occurred, combustion spreads to the entire
unburned mixture
3.5
hazardous explosive atmosphere
explosive atmosphere present in such quantities that precautions against ignition are required
3.6
minimum ignition energy
least electrical energy of a purely capacitive spark (i.e. no added inductance) required to
ignite a dust, gas or vapour
3.7
charging current
quantity of charge per unit time flowing into FIBC
3.8
cone discharge
electrostatic discharge running outwards across the surface from the top of highly charged,
insulating powder heaps in large containers
3.9
brush discharge
electrostatic discharge from a non-conductive, solid or liquid surface
3.10
spark
electrostatic discharge from an electrically isolated conductive object or surface
3.11
propagating brush discharge
highly energetic discharge from an insulating sheet, layer or coating on a conductive surface,
or a material of high resistivity and high break down voltage with the two surfaces highly
charged to opposite polarity
3.12
inner liner
integral or removable container which fits into the FIBC (synonymous with liner)
3.13
surface resistivity
equivalent to the surface resistance of a square area of material, having electrodes at two
opposite sides
3.14
volume resistivity
equivalent to the volume resistance of a cube of material with unit length, having the
electrodes at two opposite surfaces
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3.15
type qualification testing
testing used to determine the type of FIBC as specified in 4.1 and to demonstrate that FIBC
meet the requirements of Clause 7
3.16
quality control testing
testing designed to provide manufacturers and users with information that demonstrates all
FIBC produced and delivered are substantially the same as the sample FIBC used to qualify
the FIBC design
3.17
groundable point
point on FIBC designated by the manufacturer as a location to attach a grounding or earth
bonding cable or other means of earthing FIBC
NOTE There may be one or more groundable points on each FIBC. Lift loops may also be designated as
groundable points, but fortuitous earthing via lifting hooks should not be relied as these may be painted/coated, or
covered with powder etc., and so may not guarantee an adequate earth path.
4 Classification
4.1 Principles of classification for FIBC
FIBC are classified according to one of four types: Type A, Type B, Type C and Type D. The
types are defined by the construction of the FIBC, the nature of their intended operation and
associated performance requirements.
An individual design of FIBC may only be classified as one single type; for example one FIBC
cannot be simultaneously classified as both Type B and Type D, or as Type CD.
4.1.1 Type A
Type A FIBC are made from fabric or plastic sheet without any measures against the build up
of static electricity. Any FIBC that does not meet the requirements specified in Clause 7, or
which has not been tested against the requirements is classified as Type A.
4.1.2 Type B
Type B FIBC are made from fabric or plastic sheet designed to prevent the occurrence of
sparks and propagating brush discharges.
4.1.3 Type C
Type C FIBC are made from conductive fabric or plastic sheet, or interwoven with conductive
threads or filaments and designed to prevent the occurrence of incendiary sparks, brush
discharges and propagating brush discharges. Type C FIBC are designed to be connected to
earth during filling and emptying operations.
4.1.4 Type D
Type D FIBC are made from static protective fabric designed to prevent the occurrence of
incendiary sparks, brush discharges and propagating brush discharges, without the need for a
connection from the FIBC to earth.
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4.2 Principles of classification and requirements for inner liners
4.2.1 Surface resistivity measurements for inner liners
Surface resistivity shall be measured according to IEC 61340-2-3. A minimum of ten
measurements shall be made at points evenly distributed over the inner liner surface. All
measurements shall be within the limits specified for the type of inner liner being tested.
4.2.2 Special cases
Inner liners made from materials that contain a conductive layer sandwiched between two
insulating layers shall not be used in Type B or Type D FIBC. If such an inner liner is used in
Type C FIBC, the conductive layer shall be securely bonded to earth. The thickness of the
insulating layers shall be less than 700 µm, and the breakdown voltage measured between an
electrode placed on each surface in turn and the conductive layer shall be less than 4 kV,
measured according to 9.1 under the conditions specified in 8.2.
NOTE In order to avoid incendiary brush discharge, the thickness of any exposed insulating layers in contact with
non-insulating layers is limited to a maximum of 700 µm.
4.2.3 Type L1
Type L1 inner liners are made from materials with surface resistivity on at least one surface
Ω (see Annex F), measured under the conditions specified in
less than or equal to 1,0 × 10
8.2. of this standard. Type L1 inner liners may be used in Type C FIBC.
If the material is multi-layered, or if the material has one surface with surface resistivity
greater than 1,0 × 10 Ω, the breakdown voltage through the material shall be less than 4 kV,
measured according to 9.1 under the conditions specified in 8.2.
The thickness of any layer with surface resistivity greater than 1,0 × 10 Ω on the inside
(product side) of the inner liner material shall be less than 700 µm.
Permissible configurations and requirements for type L1 inner liners are summarized in
Table 1.
Table 1 – Permissible configurations and requirements for Type L1 inner liners
Parameters
Resistivity of Resistivity of
Configuration
Breakdown voltage Thickness
inside surface outside surface
V d
B
ρ ρ
I O
7 7
ρ ≤ 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω No measurement required No limit
I O
7 12
2A No measurement required No limit
ρ ≤ 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω
I O
12 7
2B No measurement required No limit
ρ ≤ 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω
I O
7 12
3 V < 4 kV No limit
ρ ≤ 1,0 × 10 Ω ρ > 1,0 × 10 Ω
B
I O
12 7
4 ρ > 1,0 × 10 Ω ρ ≤ 1,0 × 10 Ω V < 4 kV d <700 µm
I O B
4.2.4 Type L2
Type L2 inner liners are made from materials with surface resistivity on at least one surface
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between 1,0 × 10 Ω and 1,0 × 10 Ω (see Annex F), measured under the conditions
specified in 8.3. Type L2 inner liners may be used in Type B, Type C and Type D FIBC.
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If Type L2 inner liners are used in Type C FIBC, the charging current shall not exceed 3 µA.
If the material is multi-layered, or if the material has one surface with surface resistivity
Ω, the breakdown voltage through the material shall be less than 4 kV,
greater than 1,0 × 10
measured according to 9.1 under the conditions specified in 8.2.
The thickness of any layer with surface resistivity greater than 1,0 × 10 Ω on the inside
(product side) of the inner liner material shall be less than 700 µm.
Permissible configurations and requirements for Type L2 inner liners are summarized in
Table 2.
Table 2 – Permissible configurations and requirements for Type L2 inner liners
Parameters
Resistivity of Resistivity of Breakdown
Configuration
Thickness
inside surface outside surface voltage
d
ρ ρ V
I O B
No
9 12 9 12
1 1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω 1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω measurement No limit
I O
required
9 12 12
2 V < 4 kV No limit
1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω ρ > 1,0 × 10 Ω
B
I O
12 9 12
3 V < 4 kV d <700 µm
ρ > 1,0 × 10 Ω 1,0 × 10 Ω ≤ ρ ≤ 1,0 × 10 Ω
B
I I
4.2.5 Type L3
Type L3 inner liners are made from materials with surface resistivity of greater than
1,0 × 10 Ω, measured under the conditions specified in 8.2. Type L3 inner liners may be
used in Type B FIBC.
The breakdown voltage through the material shall be less than 4 kV, measured according to
9.1 under the conditions specified in 8.2.
Permissible configurations and requirements for Type L3 inner liners are summarized in
Table 3.
Table 3 – Permissible configurations and requirements for Type L3 inner liners
Parameters
Resistivity of Resistivity of Breakdown
Configuration
Thickness
inside surface outside surface voltage
d
ρ ρ V
I O B
12 12
1 V < 4 kV No limit
ρ > 1,0 × 10 Ω ρ > 1,0 × 10 Ω
B
I O
4.3 Combination of FIBC and inner liners
The inclusion of an inner liner in FIBC does not change the type classification of the FIBC.
For example, Type A FIBC with Type L1 inner liners are still Type A FIBC and are subject to
all the restrictions on use of Type A FIBC.
The requirements for breakdown voltage for FIBC and inner liners shall be applied separately.
For Type B, Type C and Type D FIBC with inner liners for which there is a breakdown voltage
requirement, two sets of breakdown voltage measurement shall be required: one set on the
FIBC material and one set on the inner liner material. For example, if a Type B FIBC is fitted
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with a Type L3 inner liner, the breakdown voltage of the FIBC material shall be measured on
its own and shall be less than 6 kV and a separate breakdown voltage measurement shall be
made on the inner liner material and it shall be less than 4 kV.
5 Safe use of FIBC
The requirements and specifications that FIBC must shall meet and the ways in which they
are used depend on the nature and sensitivity of any explosive atmosphere present during
filling and emptying. The final goal for the construction of FIBC is to exclude incendiary
discharges from the FIBC fabric during their intended use. FIBC constructed in compliance
with the requirements specified in this standard do not necessarily ensure that hazardous
electrostatic discharges, e.g. cone discharges or spark discharges from charged conductive
products, will not be generated by the contents in FIBC. Information on the risks associated
with cone discharges is given in Annex E.
The igniting ability of electrostatic discharges, i.e. sparks, brush discharges and propagating
brush discharges, is different for each type of discharge. The necessity of their exclusion and
thus the requirements and specifications for FIBC depend on the intended use of the FIBC.
The conditions in which each type of FIBC shall be used is shown in Table 4.
Table 4 – Use of different types of FIBC
Bulk product in FIBC Surroundings
b
Gas zones 1-2
b
b (Explosion groups IIA/IIB)
Dust zones 21-22
a Non-flammable
MIE of dust or
a
atmosphere (1 000 mJ ≥ MIE > 3 mJ) b
dust zones 21-22
a
(MIE ≤ 3 mJ)
c
MIE > 1 000 mJ A,B,C,D B,C,D C,D
c
B,C,D B,C,D C,D
1 000 mJ ≥ MIE > 3 mJ
d c
MIE ≤ 3 mJ C,D C,D C,D
NOTE 1 Additional precautions are usually necessary when a flammable gas or vapour atmosphere is present
inside the FIBC, e.g. in the case of solvent wet powders.
NOTE 2 Non-flammable atmosphere includes dusts having a MIE > 1 000 mJ.
a
Measured in accordance with IEC 61241-2-3, capacitive discharge circuit (no added inductance).
b
See Annex D for explanation of hazardous areas, zones and explosion groups.
c
Use of Type D shall be limited to explosion groups IIA/IIB with MIE ≥ 0,14 mJ.
d
See Annex E for explanation of the 3 mJ limit in relation to cone discharges.
The ability to safely use FIBC in hazardous explosive atmospheres may change if an inner
liner is installed in the FIBC. Combinations of FIBC and inner liner that can be used safely in
hazardous explosive atmospheres are shown in Table 5. In addition to the separate
requirements for FIBC and inner liners, there are requirements that certain combinations of
FIBC and inner liner shall meet. These requirements are also shown in Table 5.
Table 5 – Inner liners and FIBC: combinations that are permissible
and not permissible in hazardous explosive atmospheres
Inner liner
FIBC
Type L1 Type L2 Type L3
Type B Not permissible Permissible Permissible
a
Type C Permissible Permissible Not permissible
b
Type D Not permissible Permissible Not permissible
...
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