Bsi bs en 01127 2 2014

BS EN 1127-2:2014

BSI Standards Publication

Explosive atmospheres —
Explosion prevention and
protection
Part 2: Basic concepts and methodology for
mining


BS EN 1127-2:2014

BRITISH STANDARD

National foreword
This British Standard is the UK implementation of EN 1127-2:2014. It
supersedes BS EN 1127-2:2002+A1:2008 which is withdrawn.
The UK participation in its preparation was entrusted to Technical
Committee EXL/23, Explosion and fire precautions in industrial and
chemical plant.
A list of organizations represented on this committee can be
obtained on request to its secretary.
This publication does not purport to include all the necessary
provisions of a contract. Users are responsible for its correct
application.
© The British Standards Institution 2014.
Published by BSI Standards Limited 2014
ISBN 978 0 580 80561 5
ICS 13.230; 73.100.01
Compliance with a British Standard cannot confer immunity from

legal obligations.
This British Standard was published under the authority of the
Standards Policy and Strategy Committee on 30 June 2014.
Amendments/corrigenda issued since publication
Date

Text affected


BS EN 1127-2:2014

EN 1127-2

EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM

June 2014

ICS 13.230; 73.100.01

Supersedes EN 1127-2:2002+A1:2008

English Version

Explosive atmospheres - Explosion prevention and protection Part 2: Basic concepts and methodology for mining
Atmosphères explosives - Prévention de l'explosion et
protection contre l'explosion - Partie 2: Notions
fondamentales et méthodologie dans l'exploitation des
mines

Explosionsfähige Atmosphären - Explosionsschutz - Teil 2:
Grundlagen und Methodik in Bergwerken

This European Standard was approved by CEN on 7 May 2014.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2014 CEN

All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members.

Ref. No. EN 1127-2:2014 E

BS EN 1127-2:2014
EN 1127-2:2014 (E)

Contents

Page

Foreword ..............................................................................................................................................................4
Introduction .........................................................................................................................................................5
1

Scope ......................................................................................................................................................8

2

Normative references ............................................................................................................................9

3

Terms and definitions ........................................................................................................................ 10

4
4.1
4.2
4.3
4.4

Risk assessment ................................................................................................................................. 11
General ................................................................................................................................................. 11
Identification of explosion hazards................................................................................................... 11

Identification of ignition hazards ...................................................................................................... 11
Estimation of the possible effects of an explosion ......................................................................... 11

5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
5.11
5.12
5.13

Possible ignition sources .................................................................................................................. 12
Hot surfaces ........................................................................................................................................ 12
Flames and hot gases (including hot particles) .............................................................................. 12
Mechanically generated sparks......................................................................................................... 12
Electrical equipment ........................................................................................................................... 12
Stray electric currents ........................................................................................................................ 12
Static electricity .................................................................................................................................. 13
Lightning .............................................................................................................................................. 13
Radio frequency (RF) electromagnetic waves from 104 Hz to 3 × 1011 Hz (high frequency) ..... 13
Electromagnetic waves from 3 × 1011 Hz to 3 × 1015 Hz ............................................................... 13
Ionizing radiation ................................................................................................................................ 13
Ultrasonics .......................................................................................................................................... 13

Adiabatic compression and shock waves ....................................................................................... 13
Exothermic reactions, including self-ignition of dusts................................................................... 13

6
6.1
6.2
6.2.1
6.2.2

Risk reduction ..................................................................................................................................... 14
Fundamental principles ..................................................................................................................... 14
Avoidance or reduction of explosive atmosphere .......................................................................... 14
Process parameters ........................................................................................................................... 14
Design and construction of equipment, protective systems and components containing
flammable substances ....................................................................................................................... 16
6.3
Classification of hazardous atmospheric conditions ..................................................................... 16
6.3.1 General ................................................................................................................................................. 16
6.3.2 Hazardous atmospheric conditions .................................................................................................. 17
6.4
Requirements for the design and construction of equipment, protective systems and
components by avoidance of effective ignition sources................................................................ 17
6.4.1 General ................................................................................................................................................. 17
6.4.2 Hot surfaces ........................................................................................................................................ 18
6.4.3 Flames and hot gases ........................................................................................................................ 19
6.4.4 Mechanically generated sparks......................................................................................................... 19
6.4.5 Electrical equipment ........................................................................................................................... 20
6.4.6 Stray electric currents ........................................................................................................................ 20
6.4.7 Static electricity .................................................................................................................................. 20
6.4.8 Lightning .............................................................................................................................................. 20

6.4.9 Radio frequency (RF) electromagnetic waves from 104 Hz to 3 × 1011 Hz .................................. 20
6.4.10 Electromagnetic waves from 3 × 1011 Hz to 3 × 1015 Hz ............................................................... 21
6.4.11 Ionizing radiation ................................................................................................................................ 22

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EN 1127-2:2014 (E)

6.4.12
6.4.13
6.4.14
6.5
6.5.1
6.5.2
6.6
6.7

Ultrasonics ........................................................................................................................................... 22
Adiabatic compression and shock waves ........................................................................................ 22
Exothermic reactions, including self-ignition of dusts ................................................................... 22
Requirements for design and construction of equipment, protective systems and
components to reduce the explosion effects ................................................................................... 23
General ................................................................................................................................................. 23
Special equipment for underground mining..................................................................................... 23
Provisions for emergency measures ................................................................................................ 24
Principles for measuring and control systems for explosion prevention and protection ........... 24

7

7.1
7.2
7.3

Information for use .............................................................................................................................. 24
General ................................................................................................................................................. 24
Information for commissioning, maintenance and repair to prevent explosion .......................... 25
Qualifications and training ................................................................................................................. 26

Annex A (informative) Relation between categories and hazardous atmospheric conditions ................. 27
Annex B (normative) Tools for use in potentially explosive atmospheres ................................................. 28
Annex C (informative) Significant technical changes between this document and the previous
edition of this European Standard ..................................................................................................... 29
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 94/9/EC .............................................................................................. 30
Annex ZB (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2006/42/EC ........................................................................................ 31
Bibliography ...................................................................................................................................................... 32

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EN 1127-2:2014 (E)

Foreword
This document (EN 1127-2:2014) has been prepared by Technical Committee CEN/TC 305 “Potentially
explosive atmospheres - Explosion prevention and protection”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2014 and conflicting national standards shall be withdrawn

at the latest by December 2014.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 1127-2:2002+A1:2008.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directives.
For relationship with EU Directives, see informative Annexes ZA and ZB, which are an integral part of this
document.
EN 1127, Explosive atmospheres — Explosion prevention and protection is composed of the following parts:
—

Part 1: Basic concepts and methodology

—

Part 2: Basic concepts and methodology for mining (the present document)

Annex C provides details of significant changes between this document and the previous edition.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

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EN 1127-2:2014 (E)

Introduction
General
CEN and CENELEC are producing a series of standards to assist designers, manufacturers and other
interested bodies to interpret the essential safety requirements in order to achieve conformity with European
legislation. Within this series of standards, CEN has undertaken to draw up a standard to give guidance in the
field of explosion prevention and protection, as hazards from explosions are to be considered in accordance
with EN ISO 12100.
In accordance with EN ISO 12100, it is a type A standard.
Special considerations for mining
Explosions can result from:
—

materials processed or used by the equipment and components, e.g. minerals obtained as part of the
winning process;

—

materials released by the equipment and components;

—

materials in the vicinity of the equipment, protective systems and components;

—

materials of which the equipment, protective systems and components are constructed.

As the explosion protection of equipment, protective systems and components depends on:
—

the design and construction of the equipment, protective systems and components;

—

the intended use;

—

the foreseeable misuse;

—

the ambient conditions;

—

the materials extracted and handled.

This standard also includes safety aspects related to these factors, i.e. it is imperative that the manufacturer
consider how and for what the equipment, protective systems and components will be used and take this into
account during their design and construction. Only in this way can hazards inherent in equipment, protective
systems and components be reduced.
NOTE 1
This standard can also serve as a guide for users of equipment, protective systems and components when
assessing the risk of explosion in the workplace and selecting the appropriate equipment, protective systems and
components.

Mines can be either gassy or non-gassy depending upon the mineral/material being extracted and whether or
not firedamp can occur in the workings. It is usual practice to consider all coal mines as gassy mines. Noncoal mines can, however, also be susceptible to the occurrence of firedamp, e.g. if minerals/materials are
being extracted in the vicinity of oil-bearing strata or unworked coal seams which are disturbed by the

extraction process or mines susceptible to outbursts of flammable gas.
In mines where flammable minerals/materials are extracted, there can also be a risk of explosions because
small particles of the extracted product can be blown into the air to form dust/air mixtures able to support rapid
combustion. Combustible dust can either be an explosion risk on its own (when in the form of an explosive
dust/air mixture), or it can settle in layers which may be blown from the floor and sides of the roadways by a

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firedamp explosion. In the latter case, the explosive violence can increase many times as more and more fuel
in the form of combustible dust is raised by a blast wave and added to the flame as it travels along the
roadways.
The risk of an explosive atmosphere occurring and its consequences will therefore vary from mine to mine,
depending on the type of mine, its layout, the mineral being extracted and the likelihood of firedamp and/or
combustible dust occurring.
In coal mining, firedamp and coal dust naturally associated with the coal is released by the activity of the
miners. Therefore, the potential explosion risk is greater as a result of explosive air/gas or air/dust mixtures
forming that cannot be totally excluded by the preventive measures taken.
Firedamp/air mixtures are usually diluted by the ventilation and evacuated to the surface via the mine
workings so that the gas content in normal operation is kept far below the lower explosion limit. However, as a
result of system malfunction (e.g. fan failure), sudden release of large gas quantities (gas outbursts) or
intensified gas release caused by decreasing air pressure or by increased coal production, the permissible
gas concentration thresholds may be exceeded. The explosive atmosphere caused in this way, even though
limited in space and/or time, may cause a hazard not just at its point of origin but also in the escape roads,
waste air paths and other connected mine structures in the mine layout.
Coal dust/air mixtures are usually neutralized at the dust source by water sprays, dust removal systems on
heading machines and/or treating with inert dust in order to reduce the explosive potential. However, an

explosion hazard can exist if explosive dust can become airborne, e.g. at transfer points, in bunkers and other
conveying systems.
In contrast to surface industries, in gassy mines electrical and non-electrical equipment and mining personnel
are in permanent contact with gas and/or dust/air mixtures which, under unfavourable conditions, may
constitute explosive atmospheres. Accordingly, particularly stringent safety requirements are in force for
explosion protection and escape possibilities in the event of a hazard. Due to the possibly devastating effects
of underground gas/dust explosions, underground mining is permitted only well outside the explosion range.
In gassy mines, the decision as to whether or not mine workers can operate in a particular workplace depends
upon the atmospheric conditions prevailing at the time. Traditionally, a factor of safety is also introduced so
that it is common practice throughout the European member states for equipment to be de-energized or made
safe and for miners to be withdrawn from their workplace if the atmospheric conditions attain a specific
percentage of the lower explosion limit (LEL) of methane (firedamp) in air as defined by the relevant national
legislation of the member states.
NOTE 2
state.

The current limit values for disconnecting equipment and withdrawing personnel are different in each member

Two different ranges of explosive atmospheres originating from the intended installation and use of the
equipment are taken into account when dealing with requirements for Equipment Groups M 2 and M 1:
—

potentially explosive atmosphere — range between 0 % and below LEL or above UEL up to 100 % of
firedamp in air;

—

explosive atmosphere — range between LEL and UEL of firedamp in air.

In mine workings with explosive atmospheres, only M 1 equipment is acceptable as it has a very high level of

protection. M 1 equipment, e.g. telephones or gas measuring equipment may continue to be operated in
explosive atmospheres, because they are safe even in the event of rare equipment faults. This is ensured by
the existence of two independent protective measures or double fail-safe systems.
In mine workings with potentially explosive atmospheres, both M 1 and M 2 equipment may be used. M 2
equipment may be used as it has a high level of protection and is suitable for the severe conditions in mining.
In an explosive atmospheres, M 2 equipment needs to be capable of being disconnected or made safe.

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NOTE 3
Under special conditions, it might be necessary to operate M 2 equipment in an explosive atmosphere for a
short time, e.g. when personnel are escaping from mine workings with high firedamp readings with their M 2 caplights
switched on, when personnel are being recovered by the mine rescue service or the firedamp extraction system has been
started up.

M 1 and M 2 equipment can only be operated with the characteristics specified by the manufacturer as only
then do they ensure the relevant level of protection. The manufacturer specifies the operating characteristics
for the equipment.
In practice, national regulations require that gas measurements be taken at certain points and at specific
intervals and suitable measures are taken to de-energize the equipment either manually or automatically if the
firedamp concentration reaches a certain value. A subdivision into hazards caused by an explosive gas
atmosphere and those caused by an explosive dust atmosphere is, in contrast to EN 1127-1:2011, not
advisable in underground mining as the hazard to the mine workings can be caused simultaneously by
firedamp and by clouds of combustible dust. Therefore, the explosion protection measures will always cover
both, i.e. the hazard caused by firedamp and the one caused by combustible dust.
The definition of potentially explosive atmospheres in coal mines susceptible to firedamp based on

Directive 94/9/EC extends the definition of potentially explosive atmosphere to include combustible dust as
well as firedamp. Extensive research has shown that the minimum ignition energy (MIE) of coal dust/air
mixtures is several hundred times that of firedamp/air mixtures and that the maximum experimental safe gap
(MESG) of coal dust particles is more than double that for firedamp. It is therefore reasonable to assume that
the equipment, protective systems and components which are designed and constructed for use in
firedamp/air mixtures are also suitable for use in coal dust/air mixtures.
The comparison of methane and coal dust experimental data relates only to atmospheres (mixtures of gas
and/or dust with air), not to dust layers. Additional precautions are required when considering coal dust
deposits as, in this case, the maximum surface temperature of the equipment (limited to 150 °C for Group I
equipment) on which the deposits can form can be limited to values below the minimum ignition temperature.
It is vital to bear in mind that in both coal mines and non-coal mines there can be areas where firedamp does
not occur but where there is a risk of explosion because of combustible dust.

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1

Scope

This European Standard specifies methods for explosion prevention and protection in mining by outlining the
basic concepts and methodology for the design and construction of equipment, protective systems and
components.
This European Standard applies to Group I equipment, protective systems and components intended for use
in underground parts of mines and those parts of their surface installations at risk from firedamp and/or
combustible dust.
NOTE

Detailed information on specific equipment, protective systems and components is contained in the relevant
individual standards. Safety-relevant data regarding flammable materials and explosive atmospheres are required for the
design and construction of the explosion protection measures.

This European Standard specifies methods for the identification and assessment of hazardous situations that
may lead to explosions and describes the design and construction measures appropriate for the required
safety. This is achieved by
—

risk assessment;

—

risk reduction.

The safety of equipment, protective systems, and components can be achieved by eliminating hazards and/or
limiting the risk, i.e.
a)

by appropriate design (without using safeguarding);

b)

by safeguarding;

c)

by information for use;

d)

by any other preventive measures.

Measures in accordance with a) (prevention) and b) (protection) against explosions are dealt with in Clause 6
of this standard; measures according to c) against explosions are dealt with in Clause 7 of this standard.
Measures in accordance with d) are not described in this European Standard. They are dealt with in
EN ISO 12100:2010, Clause 6.
The preventive and protective measures described in this European Standard will not provide the required
level of protection unless the equipment, protective systems and components are operated in line with their
intended use and are installed and maintained according to the relevant codes of practice or requirements.
This standard is applicable to any equipment, protective systems and components intended to be used in
potentially explosive atmospheres. These atmospheres can arise from flammable materials processed, used
or released by the equipment, protective systems and components or from materials in the vicinity of the
equipment, protective systems and components and/or from the materials of construction of the equipment,
protective systems and components.
As shot firing can release potentially explosive atmospheres, this standard is also applicable to the equipment
used for shot firing, apart from the explosives and detonators.
This standard is applicable to equipment, protective systems and components at all stages of use.
This standard is not applicable to:
—

8

medical devices intended for use in a medical environment;


BS EN 1127-2:2014
EN 1127-2:2014 (E)

—

equipment, protective systems and components where the explosion hazard results exclusively from the
presence of explosives or unstable chemical substances;

—

equipment, protective systems and components where the explosion can result from reaction of
substances with oxidising agents other than atmospheric oxygen or by other hazardous reactions or
conditions other than atmospheric conditions;

—

equipment intended for use in domestic and non-commercial environments where explosive atmospheres
may only rarely be created and solely as a result of the accidental leakage of fuel gas;

—

personal protective equipment covered by Directive 89/686/EEC; the design and construction of systems
containing desired, controlled combustion processes, unless they can act as ignition sources in
potentially explosive atmospheres;

—

mines where firedamp and/or combustible dust are not naturally present and surface installations such as
coal preparation plants, power plants, coke oven plants etc. in which an explosive atmosphere can be
present, but which are not part of a coal mine. These are covered by EN 1127-1:2011.

2

Normative references

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 1127-1:2011, Explosive atmospheres — Explosion prevention and protection — Part 1: Basic concepts
and methodology
EN 1710, Equipment and components intended for use in potentially explosive atmospheres in underground
mines
EN 13237, Potentially explosive atmospheres — Terms and definitions for equipment and protective systems
intended for use in potentially explosive atmospheres
EN 13463-1:2009, Non-electrical equipment for use in potentially explosive atmospheres — Part 1: Basic
method and requirements
EN 13463-6, Non-electrical equipment for use in potentially explosive atmospheres — Part 6: Protection by
control of ignition source 'b'
EN 13478, Safety of machinery — Fire prevention and protection
EN 14373, Explosion suppression systems
EN 14460, Explosion resistant equipment
EN 14797, Explosion venting devices
EN 15089, Explosion isolation systems
EN 60079-0, Explosive atmospheres — Part 0: Equipment — General requirements
EN 60079-2, Explosive atmospheres — Part 2: Equipment protection by pressurized enclosure “p”
EN ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk
reduction (ISO 12100:2010)

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EN ISO 13849-1, Safety of machinery — Safety-related parts of control systems — Part 1: General principles
for design (ISO 13849-1)

3

Terms and definitions

For the purposes of this document, the terms and definitions given in EN 13237:2012 and the following apply.
3.1
firedamp
any potentially explosive mixture of gases or any flammable gas naturally occurring in a mine
Note 1 to entry:
As firedamp consists mainly of methane, the terms firedamp and methane are used frequently in
mining practice as synonyms.

3.2
protection against firedamp explosions
explosion prevention and protection in underground parts of mines and those parts of surface installations of
such mines liable to be endangered by firedamp and or combustible dust
3.3
component
any item essential to the safe functioning of equipment and protective systems but with no autonomous
function
[SOURCE: Directive 94/9/EC, Chapter I, Article 1, modified]
3.4
equipment
machines, apparatus, fixed or mobile devices, control components and instrumentation thereof and detection
and prevention systems which, separately or jointly, are intended for the generation, transfer, storage,
measurement, control and conversion of energy, for the processing of material, and which are capable of
causing an explosion through their own potential sources of ignition

[SOURCE: Directive 94/9/EC, Chapter I, Article 1, modified]
3.5
machinery
— an assembly, fitted with or intended to be fitted with a drive system other than directly applied human or
animal effort, consisting of linked parts or components, at least one of which moves, and which are joined
together for a specific application;
— an assembly referred to in the first indent, missing only the components to connect it on site or to sources
of energy and motion;
— an assembly referred to in the first and second indents, ready to be installed and able to function as it
stands only if mounted on a means of transport, or installed in a building or a structure;
— assemblies of machinery referred to in the first, second and third indents or partly completed machinery
which, in order to achieve the same end, are arranged and controlled so that they function as an integral
whole;
— an assembly of linked parts or components, at least one of which moves and which are joined together,
intended for lifting loads and whose only power source is directly applied human effort
[SOURCE: Directive 2006/42/EC, modified]

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3.6
minimum ignition temperature of an explosive atmosphere
ignition temperature of a combustible gas or of a vapour of a combustible liquid or the minimum ignition
temperature of a dust cloud under specified test conditions
3.7
ignition temperature
lowest temperature of a hot surface as determined under specified test conditions, at which the ignition of a

combustible substance in the form of gas or vapour mixture with air will occur
3.8
protective system
devices which are intended to halt incipient explosions immediately and/or to limit the effective range of an
explosion
Note 1 to entry:

Protective systems are separately placed on the market for use as autonomous systems.

[SOURCE: Directive 94/9/EC, Chapter I, Article 1, modified]
3.9
self-ignition of dust in bulk
ignition of dusts caused by the rate of heat generation from oxidation and/or decomposition reactions of the
dust being greater than the rate of heat loss to the surroundings

4

Risk assessment

4.1 General
In addition to EN 1127-1:2011, 4.1 the following shall apply:
In assessment of the likelihood of occurrence of a hazardous explosive atmosphere in mines, the main factors
are:
—

the properties of the mineral being worked;

—

the manner of working it;

—

the presence of firedamp in the immediate strata;

—

the effects of human action on the strata in the vicinity of the mine workings;

—

the degree of dilution by the ventilation system.

NOTE

For further information see EN 13478.

4.2 Identification of explosion hazards
EN 1127-1:2011, 4.2 shall apply.

4.3 Identification of ignition hazards
EN 1127-1:2011, 4.3 shall apply.

4.4 Estimation of the possible effects of an explosion
In addition to EN 1127-1:2011, 4.4 the following shall apply:

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EN 1127-2:2014 (E)

The expected injury to persons or damage to objects and the size of the endangered place can thus be
estimated only for each individual case.
The risk of an explosive atmosphere occurring and its consequences will therefore vary from mine to mine,
depending on the type of mine, its layout, the mineral being extracted and the likelihood of firedamp and/or
combustible dust occurring.

5

Possible ignition sources

5.1 Hot surfaces
The requirements of 5.1 of EN 1127-1:2011 apply, but special consideration shall be given to hot surfaces of
internal combustion engines.
For protective measures against ignition hazards from hot surfaces, see 6.4.2.

5.2 Flames and hot gases (including hot particles)
The requirements of 5.2 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to flames and hot gases, see 6.4.3.

5.3 Mechanically generated sparks
The requirements of 5.3 of EN 1127-1:2011 apply. During the cutting of mineral, sparks can be generated and
are very often a source of ignition.
For protective measures against ignition hazards due to mechanically generated sparks, see 6.4.4.

5.4 Electrical equipment
The requirements of 5.4 of EN 1127-1:2011 apply. During shot firing, electrical sparks can be generated by
the blasting machine and/or detached cables and leads at the time of ignition.
For protective measures against ignition hazards due to electrical equipment, see 6.4.5.

5.5 Stray electric currents
Stray currents can flow in electrically conductive systems or parts of systems
—

as return currents in power generating systems;

—

as a result of a short-circuit or of a short-circuit to earth owing to faults in the electrical installations;

—

as a result of magnetic induction (e.g. near electrical installations with high currents or radio frequencies,
see also 5.8);

—

as a result of lightning (see 5.7) and

—

as a result of induction from surface overhead lines.

If parts of a system able to carry stray currents are disconnected, connected or bridged - even in the case of
slight potential differences - an explosive atmosphere can be ignited as a result of electric sparks and/or arcs.
Moreover, ignition can also occur due to the heating up of these current paths (see 5.1).
For protective measures against ignition hazards due to stray electric currents, see 6.4.6.

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5.6 Static electricity
The requirements of 5.6 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to static electricity, see 6.4.7.

5.7 Lightning
The requirements of 5.7 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to lightning, see 6.4.8.

5.8 Radio frequency (RF) electromagnetic waves from 104 Hz to 3 × 1011 Hz (high frequency)
The requirements of 5.8 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to electromagnetic waves in the RF spectrum, see 6.4.9.

5.9 Electromagnetic waves from 3 × 1011 Hz to 3 × 1015 Hz
The requirements of 5.9 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to electromagnetic waves in this spectral range,
see 6.4.10.

5.10 Ionizing radiation
The requirements of 5.10 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to ionizing radiation, see 6.4.11.

5.11 Ultrasonics
The requirements of 5.11 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to ultrasonics, see 6.4.12.

5.12 Adiabatic compression and shock waves
The requirements of 5.12 of EN 1127-1:2011 apply.
For protective measures against ignition hazards due to adiabatic compression and shock waves, see 6.4.13.

5.13 Exothermic reactions, including self-ignition of dusts
The requirements of 5.13 of EN 1127-1:2011 apply. In mines, special attention shall be paid to the self-ignition
of coal at all times.
For protective measures against ignition hazards due to exothermic reactions, see 6.4.14.

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6

Risk reduction

6.1 Fundamental principles
The necessity for the simultaneous presence of an explosive atmosphere and effective ignition source and the
anticipated effects of an explosion as described in Clause 4 lead immediately to the three basic principles of
explosion prevention and protection in the following order:
a)

b)

Prevention:
1)

avoid or reduce explosive atmospheres. This objective can mainly be achieved by modifying either
the concentration of the flammable substance to a value outside the explosion range or the
concentration of oxygen to a value below the limiting oxygen concentration (LOC);

2)

avoid any possible effective ignition source. This is achieved by a suitable design of the equipment,
protective systems and components;

3)

de-energize equipment containing an ignition source when there is an explosive concentration.

Protection: limiting the effects of explosions to an acceptable degree. This can be done to a certain extent
by constructional protective measures. In contrast to the measures described above, here the occurrence
of a starting explosion is taken into account.

The elimination or minimization of risk can be achieved by applying one or more of the above prevention or
protection principles.
The avoidance of an explosive atmosphere shall always be the first choice.
The more likely the occurrence of an explosive atmosphere is, the higher the extent of measures against
effective ignition sources shall be and vice versa.
To allow selection of the appropriate measures, an explosion safety concept shall be developed for each
individual case.
In the planning of explosion prevention and protection measures, consideration shall be given to normal
operation, which includes start-up and shut-down. Moreover, possible technical malfunctions as well as
foreseeable misuse (see EN ISO 12100) shall be taken into account. Application of explosion prevention and
protection measures requires a thorough knowledge of the facts and sufficient experience. It is thus highly
advisable to seek expert guidance.

6.2 Avoidance or reduction of explosive atmosphere
6.2.1

Process parameters

6.2.1.1
Substitution or reduction of the amount of substances capable of forming explosive
atmospheres
Wherever possible flammable substances, e.g. mineral oil for lubricating machines, shall be replaced by nonflammable substances or by substances not capable of forming explosive atmospheres, e.g. use of “water-inoil emulsions” for hydraulic roof supports instead of mineral oil.
As far as reasonably practicable, the amount of flammable material shall be reduced to the minimum, e.g. by
firedamp drainage or by dust control measures.
The content of firedamp in the air can be substantially reduced by firedamp drainage before and during
winning operations.

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6.2.1.2

Limitation of concentration

If it is not possible to avoid the occurrence or handling of substances that are capable of forming explosive
atmospheres, the formation of a hazardous amount of an explosive atmosphere inside and/or outside the
equipment, protective systems and components can be prevented or limited by measures to control the
amount and/or concentration.
These measures shall be monitored if the concentrations inherent in the process are not sufficiently outside
the explosion range.

Such monitoring, e.g. gas detectors or flow detectors, shall be coupled to alarms, other protective systems or
automatic emergency functions.
When carrying out these control measures, the concentration of the flammable substances shall be sufficiently
below the lower explosion limit outside equipment. Inside equipment, e.g. firedamp drainage pipes, the
concentration of flammable substances shall be sufficiently outside the explosion range. Precautions shall be
taken to minimize the risks during start up or shut down of the process when the concentrations can reach the
explosion range.
The limitation of the concentration of dust can be achieved by eliminating the dust at its place of formation
(e.g. by exhaust ventilation or by water spraying) as well as by immobilization of deposited dust (e.g. by
addition of hygroscopic substances).
6.2.1.3
a)

b)

Inerting/pressurizing

Inside equipment:
1)

use of systems with pressurized apparatus in accordance with EN 60079-2;

2)

the addition of inert gases (e.g. nitrogen, carbon dioxide) can prevent the formation of explosive
atmospheres (inerting);

3)

inerting by the use of inert gases is based on reduction of the oxygen concentration in the

atmosphere so that the atmosphere is no longer explosive. The highest permissible oxygen
concentration is derived by applying a safety factor to the limiting oxygen concentration;

4)

for mixtures of different flammable substances, including hybrid mixtures, the component with the
lowest limiting oxygen concentration shall be used in the determination of the highest permissible
oxygen concentration, unless measurements have shown otherwise.

Outside equipment:
1)

for hazardous situations, such as fire fighting or preventing spontaneous combustion, the techniques
described for inside equipment may also be used for outside equipment;

2)

explosive dust-air mixtures can also be made inert by adding a compatible inert dust.

NOTE
In general, this is achieved by timely addition of a sufficient amount of limestone dust to the deposited
dispersible coal dust. The necessary amount is specified in national legislation.

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6.2.2 Design and construction of equipment, protective systems and components containing

flammable substances
6.2.2.1

General

In the planning stage of equipment, protective systems and components which will contain flammable
substances, efforts shall be made to keep the substances in closed systems at all times, e.g. firedamp
drainage systems, dust extraction systems and diesel fuel tanks.
Non-flammable or fire-resistant materials shall be used wherever possible (see EN 13478).
6.2.2.2

Minimization of releases of flammable substances

To minimize the explosion risk outside the equipment, protective systems and components due to leakage of
flammable substances, such equipment, protective systems and components shall be designed, constructed
and operated so that they are and remain leak-free. However, experience shows that small leaks are likely to
occur in certain cases, e.g. at some pump glands and sampling points. This shall be taken into account in the
design of the equipment, protective systems and components. Arrangements shall be made to limit leak rates
and to prevent the flammable substances from spreading. Where necessary, a leak detector shall be fitted.
6.2.2.3

Dilution by ventilation

Ventilation is of paramount importance in the control of the effects of releases of flammable gases and
vapours. It can be used inside and outside equipment, protective systems and components.
For dusts, ventilation generally provides sufficient protection only when the dust is extracted from the place of
origin (local extraction) and hazardous deposits of combustible dust are reliably prevented.

6.3 Classification of hazardous atmospheric conditions
6.3.1

General

Large parts of mines can be endangered at the same time by both firedamp and combustible dust and so it is
inadvisable to subdivide the hazards into those which are caused by the gas atmosphere and those by the
dust atmosphere. Therefore, measures for explosion prevention and protection shall cover both the hazards
from firedamp and the hazards from combustible dust.
Due to the possibility of disastrous effects of underground firedamp/dust explosions, mining is carried out only
well outside the explosion range. Traditionally, a factor of safety is also introduced so that it is common
practice throughout the European member states for equipment to be de-energized or made safe and for
miners to be withdrawn from their workplace if the atmospheric conditions attain a specific percentage of the
lower explosion limit (LEL) defined by national legislation.
NOTE 1
It is ensured by the layout and management of the mine, the rating of the ventilation, the firedamp drainage
ventilation etc. that during normal operation the limits (permissible concentration) laid down in the respective national
legislation are not exceeded.

The limit of the firedamp content in the underground ventilation air can be exceeded under abnormal
conditions locally and temporarily. The potentially explosive atmosphere developed in this manner is removed
by the ventilation and can thus endanger large parts of the mine along the exhaust air path.
NOTE 2
Mine workings where a hazardous explosive atmosphere is not likely to occur are classified as not dangerous.
These include in general the intake air shafts and continuously ventilated workings in the area around the pit bottom of
these shafts. They can also include workings where there is evidence that a concentration of methane specified by
national legislation is not exceeded. However, influences of mining on these workings can still introduce hazards.

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EN 1127-2:2014 (E)

In determining hazardous situations in mines, the word “zone” is intentionally not used as this notion is used
for a space of specific dimensions around a technical plant.
6.3.2

Hazardous atmospheric conditions

The hazardous atmospheric conditions are classified as follows:
Explosive atmosphere: underground parts of mines and associated surface installations of such mines
endangered by firedamp and/or combustible dusts.
NOTE 1
This includes mine workings where the concentration of firedamp is within the explosion range e.g. as a result
of malfunction (e.g. breakdown of fans), sudden release of large amounts of firedamp (gas outburst) or increased gas
emission (due to decrease of air pressure or increased coal winning).

Potentially explosive atmosphere: underground parts of mines and associated surface installations of such
mines likely to be endangered by firedamp and/or combustible dusts.
NOTE 2
This includes mine workings where the concentration of firedamp in the ventilating current or in the firedamp
drainage system is outside the explosion range.

6.4 Requirements for the design and construction of equipment, protective systems and
components by avoidance of effective ignition sources
6.4.1

General

In mines where firedamp can contain significant proportions of flammable gases other than methane,
equipment, protective systems and components shall be designed and constructed in accordance with the

requirements relating to group I and also with the requirements relating to group II for the relevant gas.
When equipment, protective systems and components are used in hazardous conditions, checks shall be
made to see whether ignition hazards can occur, by considering the ignition processes described in Clause 5
of EN 1127-1:2011. If ignition hazards are possible, efforts shall be made to remove the sources of ignition
from those situations. If this is not possible, the protective measures described in 6.4.1 to 6.4.14 shall be
implemented with attention being paid to the following.
The measures shall render the sources of ignition harmless or shall reduce the likelihood of effective ignition
sources occurring. This can be achieved by proper design and construction of equipment, protective systems
and components, by operational procedures and also by means of appropriate measuring and control systems
(see 6.7).
NOTE 1
This will also be achieved by using only equipment, protective systems and components intended for
monitoring, averting, reducing or fighting explosion hazards/damages or for warning, self-aid or rescuing endangered
persons in cases where the firedamp concentration is above the permissible limit.
NOTE 2
Directive 94/9/EC specifies different categories of equipment which reflect the requirements of the different
atmospheric conditions.

The criteria determining the classification into categories are the following:
Category M 1 comprises equipment designed and, where necessary, fitted with additional special means of
protection to be capable of functioning in conformity with the operational parameters established by the
manufacturer and ensuring a very high level of protection.
Equipment in this category is intended for use in underground parts of mines as well as those parts of surface
installations of such mines endangered by firedamp and/or combustible dust.
Equipment in this category shall remain functional even in the event of rare equipment faults in an explosive
atmosphere and has explosion protection measures so that:

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EN 1127-2:2014 (E)

—

in the event of failure of one means of protection, at least an independent second means provides the
requisite level of protection;

—

or the requisite level of protection is ensured in the event of two faults occurring independently of each
other.

Category M 2 comprises equipment designed to be capable of functioning in conformity with the operational
parameters established by the manufacturer and ensuring a high level of protection.
Equipment in this category is intended for use in underground parts of mines as well as those parts of surface
installations of these mines likely to be endangered by firedamp and/or combustible dust.
This equipment is intended to be de-energized in the event of an explosive atmosphere.
The means of protection relating to equipment in this category ensure the requisite level of protection during
normal operation and also in the case of more severe operating conditions, in particular those arising from
rough handling and changing environmental conditions. Requirements related to explosion protection and
prevention for construction and marking of equipment and components are defined in EN 1710.
The relation between categories and atmospheric conditions is illustrated in Annex A.
Depending on the category, the following general requirements for equipment, protective systems and
components shall be complied with:
Category M 2: Sources of ignition shall not become effective during normal operation - even in the event of
severe operating conditions and especially in rough operation and changing environmental conditions.
Category M 1: In addition to the avoidance of sources of ignition specified for category M 2, sources of
ignition that can occur in rare incidents only shall be avoided.
All categories: If the explosive atmosphere contains several types of flammable gases or dusts, the

protective measures shall generally be based on the results of special investigations.
Avoidance of effective ignition sources as the only safety measure is only applicable if all types of ignition
sources have been identified and are effectively avoided. The specific requirements for the avoidance of the
various types of ignition sources in the different atmospheric conditions are described in 6.4.2 to 6.4.14.
6.4.2

Hot surfaces

For the identification of hazards due to hot surfaces, see 5.1.
If hazards due to hot surfaces have been identified, depending on the type of explosive atmosphere (firedamp
and/or combustible dust) and on the category, the equipment, protective systems and components shall meet
the following requirements:
Category M 1: The temperatures of all equipment, protective system and component surfaces which can
come into contact with explosive atmospheres shall not - even in the case of rare malfunctions - exceed:
—

80 % of the minimum ignition temperature of the firedamp, in degrees Celsius and/or

NOTE 1

—

This is usually measured as the maximum surface temperature of 450 °C for Group I equipment.

2/3 of the minimum ignition temperature of the dust/air mixture concerned, in degrees Celsius.

Moreover, the temperature of surfaces on which dust can be deposited shall not exceed 150 °C; this shall be
ensured even in the case of rare malfunctions.

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EN 1127-2:2014 (E)

Category M 2: The temperatures of all equipment, protective systems and component surfaces which can
come into contact with explosive atmospheres during normal operation - even under severe operating
conditions, especially in rough operation and changing environmental conditions - shall not exceed:
—

80 % of the ignition temperature of the firedamp, in degrees Celsius and/or

NOTE 2

—

This is usually measured as the maximum surface temperature of 450 °C for Group I equipment

2/3 of the minimum ignition temperature of the dust/air mixture concerned, in degrees Celsius.

Moreover, the temperature of surfaces on which dust can be deposited shall not exceed 150 °C.
NOTE 3

6.4.3

For reciprocating internal combustion engines, see EN 1834–2.

Flames and hot gases

For the identification of hazards from flames and hot gases, see 5.2 of EN 1127-1:2011. As far as hot solid

particles (e.g. flying sparks) are concerned, reference is made to 6.4.4 (mechanically generated sparks) and
to 6.5.1 in connection with the flame propagation.
If hazards due to flames and/or hot gases have been identified, depending on the category, the equipment,
protective systems and components shall meet the following requirements:
Category M 2: Naked flames for operational and other intended purposes are not permitted.
In addition to naked flames, gases from flames, (e.g. for inerting purposes) or other heated gases are
permitted unless special preventive measures are taken, e.g. restricting the temperature or eliminating
explosive particles. This applies to normal operation, even under severe operating conditions and especially in
rough operation and changing environmental conditions.
Category M 1: The requirements for category M 2 shall be met even in the case of rare malfunctions.
6.4.4

Mechanically generated sparks

For the identification of hazards due to mechanically generated sparks, see 5.3.
Frictional sparks, caused by the cutting tools of winning machines when cutting hard rock with quartz or iron
pyrites inclusions, cannot always be avoided, but the risk of them causing an ignition of a gas/dust
atmosphere can be reduced considerably by the use of suitable water spray systems mounted on the machine
or by specially designed cutting tools. If this ignition hazard has been identified, a water spray system shall be
arranged around the cutting head, so that any frictional/impact sparks are quenched, the amount of airborne
dust is reduced and fresh air is fed to the cutting tools to dilute any gas released as part of the winning
process. These water spray systems shall be monitored and interlocked with the machine controls in order to
ensure that cutting cannot be take place without the water sprays functioning as designed and in the spray
pattern intended.
If hazards due to mechanically generated sparks have been identified, depending on the type of explosive
atmosphere (firedamp and/or combustible dust) and on the category, the equipment, protective systems and
components shall meet the following requirements:
Category M 1: Equipment, protective systems and components which, even in the case of rare malfunctions,
can generate explosive friction, impact or abrasion sparks are not permitted.
Category M 2: Equipment, protective systems and components which generate explosive friction, impact or

abrasion sparks during normal operation and under severe operating conditions, particularly rough handling
and changing ambient influences, shall be equipped with sufficient protective means to prevent the ignition
source from becoming effective.

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EN 1127-2:2014 (E)

All categories: The use of light metals for uncovered surfaces of equipment, protective systems and
components is only permitted if:
a)

the total content of aluminium, magnesium, titanium and zirconium does not exceed 15 % and

b)

the total content of magnesium, titanium and zirconium does not exceed 7,5 %.

The requirements for tools for use in potentially explosive atmospheres shall be in accordance with Annex B.
It is possible in many cases to protect light metals from mechanical contact with rust by coating. If coated with
non-conductive materials such as plastics, precautions against static electricity can be necessary. The coating
should not contain high percentages of aluminium.
The likelihood of mechanically generated sparks capable of ignition can be reduced, for example, by wetting.
Possible reactions with the wetting medium should be taken into account (e.g. production of hydrogen in the
case of water and light metals).
NOTE
Analyses of industrial events and results of investigations have proven that with low circumferential velocities
(velocity ≤ 1 m/s), there is no hazard of ignition of dust/air mixtures with mechanically generated sparks.

6.4.5

Electrical equipment

For the identification of hazards arising from electrical equipment, see 5.4.
Electrical equipment shall be designed, constructed, installed and maintained in accordance with the relevant
European Standards.
6.4.6

Stray electric currents

For the identification of hazards arising from stray electric currents, see 5.5.
If hazards due to stray electric currents have been identified, all the external conductive parts of the
equipment, protective systems and components shall be equipotentially bonded to each other with conductors
of adequate current carrying capacity and/or, if possible, bonded to earth in order to prevent explosive arcs or
temperature rises occurring as a result of these stray electric currents.
6.4.7

Static electricity

For the identification of hazards due to static electricity, see 5.6 of EN 1127-1:2011.
If hazards due to static electricity have been identified, the requirements of EN 13463-1:2009, 6.7 and of
EN 60079-0 apply. This information shall be included in the information for use (see Clause 7).
NOTE

6.4.8

For further information on this subject, see Technical Report CLC/TR 50404.

Lightning

For the identification of hazards due to lightning, see 5.7 of EN 1127-1:2011.
If hazards due to lightning have been identified, they shall be reduced to an acceptable level by measures
applied above ground to prevent the lightning strikes from being transmitted to the underground workings by
interconnecting equipment such as pipes and/or electric cables, e.g. by the use of surge diverters to separate
surface electrical circuits from underground electrical circuits.
6.4.9

Radio frequency (RF) electromagnetic waves from 104 Hz to 3 × 1011 Hz

For the identification of hazards due to radio-frequency electromagnetic waves, see 5.8 of EN 1127-1:2011.

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EN 1127-2:2014 (E)

If hazards due to radio frequency electromagnetic waves have been identified, a safety distance shall be
maintained in all directions between the nearest radiating parts and the receiving aerial in the potentially
explosive atmosphere (see 6.4.9 of EN 1127-1:2011).
NOTE 1
direction.

For transmission systems with a directional pattern, it is worth noting that this safety distance depends on the

If an adequate safety distance cannot be maintained, other protective measures shall be taken, for example
limiting the power output of the transmitter or shielding.
NOTE 2

Operating permits on the level of electromagnetic interference, issued by the national Telecom Authority for
example, the respective radio interference protection label or information on the degree of radio interference do not
contain any information about whether the device or its radiation field is an ignition risk.
NOTE 3
The wireless intercommunication systems commonly used in mining generally do not produce such hazards
as the power output is usually so limited that arcs cannot be struck.
NOTE 4
See EN 50303 for further guidance on RF transmitters of category M 1. This standard specifies a maximum
power output of 6 W for the prevention of ignition of the atmosphere by RF transmitters.

RF equipment and systems for use in potentially explosive atmospheres shall also comply with 6.4.5.
6.4.10 Electromagnetic waves from 3 × 1011 Hz to 3 × 1015 Hz
For the identification of hazards arising from this spectral range of electromagnetic waves, see 5.9 of
EN 1127-1:2011.
Note shall be taken that equipment, protective systems and components that generate radiation (e.g. lamps,
electric arcs, lasers) can also be a source of ignition as defined in 6.4.2 and 6.4.5.
If hazards due to electromagnetic waves from 3 × 1011 Hz to 3 × 1015 Hz have been identified, depending on
the category, the equipment, protective systems and components shall meet the following requirements:
All categories: Devices which can cause ignition by resonance absorption (see 5.9 of EN 1127-1:2011) are
not permitted.
Category M 2: Electrical equipment which generates radiation are permitted provided that:
a)

the energy of a radiated pulse or energy flux (power) of continuous radiation is limited to such a low value
that it cannot ignite the explosive atmosphere; or

b)

the radiation is safely enclosed ensuring that:
1)

any escape of radiation from the enclosure into the hazardous area that could ignite the explosive
atmosphere is safely prevented and hot surfaces that could ignite the explosive atmosphere on the
outside of the enclosure do not occur due to the radiation, and

2)

the explosive atmosphere cannot penetrate into the enclosure or an explosion inside the enclosure
cannot propagate into the potentially explosive atmosphere.

This shall be ensured during normal operation and also in the case of more severe operating conditions.
Category M 1: In addition to the conditions for category M 2, the equipment shall be designed and
constructed so that sources of ignition do not become effective even in the event of rare malfunctions (see
EN 50303 with regard to the power level and flux density permitted for optical laser transmission equipment).

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6.4.11 Ionizing radiation
For the identification of hazards arising from ionizing radiation, see 5.10 of EN 1127-1:2011.
If hazards due to ionizing radiation have been identified, the requirements of 6.4.5 shall be met for the
electrical systems needed for operation of the sources of radiation.
Electrical equipment generating ionizing radiation is permitted provided that the energy of a radiated pulse or
energy flux (power) of continuous radiation is limited to such a low value that it cannot ignite the explosive
atmosphere.
6.4.12 Ultrasonics
For the identification of hazards arising from ultrasonics, see 5.11 of EN 1127-1:2011.

If hazards due to ultrasonics have been identified, ultrasonic waves with a frequency of more than 10 MHz are
not permitted, unless the absence of an ignition risk is proved for the case in point by demonstrating that there
is no absorption due to molecular resonance.
Ultrasonic waves are permitted only if the safety of the work procedure is ensured. The power density of the
2
generated acoustic field shall not exceed 1 mW/mm , unless it is proved for the case in point that ignition is
not possible.
6.4.13 Adiabatic compression and shock waves
For the identification of hazards due to adiabatic compression and shock waves, see 5.12 of EN 1127-1:2011.
If hazards due to adiabatic compression and/or shock waves have been identified, depending on the category,
the equipment, protective systems and components shall meet the following requirements:
Category M 1: Processes that can cause compressions or shock waves which could produce ignition shall be
avoided. This shall be ensured even in the case of rare malfunctions. As a rule, hazardous compressions and
shock waves can be eliminated if, for example, the valves between sections of the system where high
pressure ratios are present can only be opened slowly.
Category M 2: Processes which can cause adiabatic compressions or shock waves during normal operation
that could ignite explosive atmospheres shall be avoided.
If equipment, protective systems and components containing highly oxidizing gases are used, special
precautions should be taken to prevent the ignition of materials and auxiliary materials.
6.4.14 Exothermic reactions, including self-ignition of dusts
For the identification of hazards due to exothermic reactions, see 5.13.
If hazards due to exothermic reactions have been identified, substances with a tendency to self-ignition shall
be avoided whenever possible. If such substances are handled, the necessary protective measures shall be
agreed in each individual case.
If the hazard of self-ignition of the minerals and substances extracted underground exists, adequate
prevention measures shall be applied (e.g. removal of the substances, control of the reactions by chemicals,
separate isolated ventilation or enclosure, minimization of air leakages through ancient workings).

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6.5 Requirements for design and construction of equipment, protective systems and
components to reduce the explosion effects
6.5.1

General

If the measures described in 6.2 or 6.4 cannot be implemented or are not advisable, the equipment, protective
systems and components shall be designed and constructed to limit the effects of an explosion to a safe level
using any of the following measures:
—

explosion-resistant design according to EN 14460;

—

explosion relief according to EN 14797;

—

explosion suppression according to EN 14373;

—

prevention of flame and explosion propagation according to EN 15089.

These measures generally relate to the limitation of hazardous effects of explosions inside equipment,

protective systems and components.
NOTE
Additional requirements can be necessary for buildings or surroundings of equipment, protective systems and
components, but these are not dealt with in this European Standard.

WARNING — In connected equipment, protective systems, components, pipeworks or elongated
vessels, it is possible that an explosion will propagate through the entire system with flame front
acceleration. Built-in elements or obstacles which increase the turbulence (e.g. measuring baffle
plates) can also accelerate the flame front. Depending on the geometry of the system, such
acceleration can lead to a transition from deflagration to detonation where high pressure pulses
occur.
In underground mining (including the corresponding aboveground areas), the considerations shall not be
limited to the interior of equipment, safety systems and components. Interactions between these facilities and
any hazardous explosive atmospheres in the surrounding mine workings shall always be taken into account.
Many of the measures described in the above mentioned European Standards can be applied fully in surface
installations of the mines, but they are applicable only to a limited extent or only in a specific mining-related
design underground. Therefore, in explosion prevention and protection for underground mining, the main
emphasis shall be on the avoidance of ignition sources.
6.5.2
6.5.2.1

Special equipment for underground mining
Explosion suppression systems

Explosion suppression systems (e.g. as automatic explosion extinguishing installations) shall consist of an
automatic flame detection system with trigger unit and extinguishing unit with extinguishing agent reservoir
and extinguishing nozzles. The contents of the extinguishing agent reservoirs shall be rapidly injected into the
area of the incipient explosion and distributed as uniformly as possible.
NOTE

See EN 14591-4.

6.5.2.2

Explosion barriers

Explosion barriers shall be designed to prevent the propagation of the explosion front to other galleries or to
other underground workings and shall be effective in the whole cross-section of the respective underground
workings.
NOTE

See EN 14591-2.

23