Principles of Ex-Protection - Basics - Crouse-Hinds

Principles of Ex-Protection - Basics - Crouse-Hinds

Principles of
Principles of Ex-Protection - Basics - Crouse-Hinds
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Principles of Ex-Protection - Basics - Crouse-Hinds
Table of Contents
1   Basics
    The history of explosion-protection and the legislative provisions .............................................. 4
    Physical principles of explosion-protection .................................................................................. 6
    Explosion-protection concepts .................................................................................................... 9
    Hazardous areas ........................................................................................................................ 10
    Gas-Ex areas .............................................................................................................................. 11
    Dust-Ex areas ............................................................................................................................ 12

2   European directives on explosion protection
    European Ex-directives .............................................................................................................. 13
    ATEX directive 2014/34/EU ....................................................................................................... 14
    Directive 1999/92/EC ................................................................................................................ 19

3   Explosion protected electrical equipment
    Explosion-protected Electrical Equipment: Basics .................................................................... 21
    Equipment protection level EPL ............................................................................................... 23
    Type of protection to EN 60079 ................................................................................................. 27
    Explosion protected mechanical equipment
    Explosion-protected Mechanical Equipment; Requirements ..................................................... 50
    Safety devices according to EN 50495
    Safety devices for the safe operation of equipment with regard to explosion risks .................. 51
    Marking of electrical equipment for use in potentially explosive atmospheres ......................... 52

4   Erection, operation, maintenance and repair
    Requirements for the erection, operation, maintenance and repair .......................................... 55
    Design, selection and erection of electrical installations according to EN 60079-14 ................. 55
    Operation of installations in hazardous areas ............................................................................ 58
    EN 60079-17; Explosive atmospheres - Part 17:
    Electrical installations, inspection and maintenance.................................................................. 59
    Continuous supervision ............................................................................................................. 60

5   Marking of degree of protection
    Marking of degree of protection of electrical equipment for use in explosive atmospheres ..... 61

6   IECEx and UNECE
    IECEx Conformity Assessment System..................................................................................... 63
    UNECE....................................................................................................................................... 64

7   Wall chart Ex-marking - NEC/CEC code digest - overview
    ATEX/IECEx and NEC/CEC ........................................................................................................ 65
Principles of Ex-Protection - Basics - Crouse-Hinds
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2                                             EATON                               
Principles of Ex-Protection - Basics - Crouse-Hinds
                          This publication provides a brief
                          survey of the essential aspects
                          of explosion-protection.
                          The statutory regulations
                          define the obligatory duties of
                          manufacturers, installers and
                          operators of electrical installa-
                          tions in explosive atmospheres.
                          Important hints you will also
                          find in the regulations of the
                          professional associations.
                          Eaton‘s Crouse-Hinds Division
                          seminars imparts expert know-
                          ledge in explosion protections
                          in theory and practice.
                          de/seminar-explosionsschutz/)   EATON                                          3
Principles of Ex-Protection - Basics - Crouse-Hinds
Principles of Explosion-Protection
1                       The history of explosion-protection and the legislative provisions

The history of explosion-             Light switches had to be installed
protection and the legislative        outside of the hazardous loca-
provisions                            tions, and in the case of a failure
As early as 1909 Concordia Ele-       or the lack of explosion-protected
ktrizitäts-Aktiengesellschaft, lat-   lighting, access to these loca-
er called CEAG, began to manu-        tions was only permitted with
facture firedamp-protected            safety lamps. Therefore, in gen-
electrical miners’ lamps for the      eral, electrical installations were
mining industry. Until then, only     not used in hazardous locations.
lamps with a naked flame were
available. The first contribution
                                      Machines with slip rings or
to safety was made in1815 by
                                      commutators had to be de-
the English chemist, Sir Hum-
                                      signed in such a way that the
phry Davy, who developed an
                                      slip ring or commutator was, at
oil lamp that prevented the
                                      least, enclosed and the enclo-
propagation of the flame by
                                      sure purged thoroughly under
means of a close-meshed
                                      overpressure with extraneous
screen. The elementary experi-
                                      air or a suitable gas. Purging
ments carried out by Dr.-Ing.
                                      had to start prior to switching
e.h. Carl Beyling, a mining engi-
                                      on the machine or the machine
neer, relating to the specially
                                      had to be built into a flameproof
protected electrical motors and
                                      enclosure. This requirement ap-
apparatus in coal mines against
                                      plied to all locations where ex-
firedamp were a decisive step
                                      plosive gas or vapour/air mix-
in the development of explo-
                                      tures might occur.
sion-protection. The governing
design principles of firedamp
protection devices on electrical      The first German regulations on
machines, transformers and            the subject of the protection of
switchgear issued in 1912 were        hazardous installations were the
based on the results of these         “Guiding principles on the instal-
experiments.                                                                Firedamp-proof miner‘s lamps (combustion lamps)
                                      lation of electrical equipment in
The following types of protec-        hazardous production areas and
tion were accepted as protec-                                               specifications and introduced
                                      storage rooms (VDE 0165/1935),
tive measures:                                                              the Ex identification marking for
                                      which were issued in 1935.
                                                                            electrical apparatus built in com-
                                                                            pliance with it.
• Oil immersion

• Closed encapsulation
                                                                            The governing principles and
• Plate encapsulation                                                       specifications of the VDE regula-
• Close-meshed screen
                                               Flameproof                   tions 0165 and 0171 were the
• Labyrinth encapsulation
                                                enclosure                   basis of the police decree dated
                                                                            13.10.1943 for electrical appara-
• “Flat joint” encapsulation                                                tus in hazardous locations and in
                                                                            mines subject to the hazard of
                                                                            firedamp. The police decree was
From 1924 incandescent lamps          The fundamental revision of           primarily aimed at the manufac-
only were permitted for lighting      these regulations began with          turers of electrical apparatus. It
                                      the VDE regulations 0171 “Con-        specified that explosion-protect-    Research papers by
hazardous areas, whereby the
                                                                            ed electrical equipment could        Carl Beyling, mining engineer
luminous element was hermeti-         structional regulations for explo-
cally sealed. The incandescent        sion-protected apparatus”,            only be placed on the market, in-
lamps had to be protected with        which came into force in 1943.        stalled and operated if it con-
a strong glass that also tightly      They provided the manufactur-         formed to the so-called VDE reg-
enclosed the lamp holder.             ers of electrical equipment for       ulations and had successfully
                                      use in potentially ex plosive at-     passed the specified type and
                                      mospheres with the necessary          routine tests.
                                      documents for a safe design
                                      and construction.
                                                                            The responsible factory inspec-

                                                                            torate division was chosen to be
                                      The regulation not only de-           the competent authority to de-
                                      scribed the individual types of       fine to what extent a room or
                                      protection and the scope of           plant might be subject to the
                                      their application, but also includ-   hazard of explosion.
                                      ed a number of constructional

                                                                                                                 Police degree dated13.10.1943

 4                                                                    EATON                                        
Principles of Ex-Protection - Basics - Crouse-Hinds
Principles of Explosion-Protection
                                              The history of explosion-protection and the legislative provisions                          1
                                 The “Decree concerning electri-        Directive 94/9/EC on the ap-
                                 cal installations in potentially ex-   proximation of the laws of the
                                 plosive atmospheres (ExVO)”,           Member States concerning
                                 which was issued in 1963, not          equipment and protective sys-
                                 only introduced the obligation to      tems for use in potentially ex-
                                 have the explosion-protected           plosive atmospheres, issued on
                                 apparatus tested by the Federal        23.03.1994 by the European
                                 Physico-Technical Institute            Parliament and Council, irrevo-
                                 (Physikalisch-Technische Bun-          cably replaced any previous di-
                                 desanstalt PTB) or the Mining          rectives concerning explosion-
                                 Test Station (BVS), but also the       protection that existed on a
                                 obligation to obtain the design        European level from 01.07.2003.
                                 approval from the authorities of
                                 the competent federal state.
                                                                        On 12.12.1996, Directive 94/9/
                                                                        EC was converted into national
                                 In 1975 the Council of the Euro-       law by the second decree con-
                                 pean Community issued frame-           cerning the equipment safety          ElexV from 1980
                                 work directives on explosion-          law and the changes relating to
                                 protection. The European               the equipment safety law by           The BetrSichV replaces the
                                 standards for electrical equip-        the explosion-protection decree       ElexV for explosion protection.
                                 ment for use in hazardous areas        (ExVO). With this decree, the         However, within the scope of
                                 were drawn up by CENELEC,              acetyl decree (AcetV), the            the transitional regulations, the
                                 the “European committee for            decree on flammable liquids           ElexV could still be applied for
                                 electro-technical standardiza-         (VbF) and the ElexV were also         installations that were commis-
                                 tion”. In Germany the new Euro-        brought into line with the            sioned before 03.10.2002.
                                 pean standards EN 50 014 to            European law.
                                 EN 50 020 were adopted in the
                                 national standards as VDE                                                    On 19.04.2014 Directive
                                 standards. These new stand-            On 28.01.2000, Directive              2014/34/EU, the successor di-
                                 ards DIN EN 50014 to 50020/            1999/92/EC of the European            rective to 94/9/EC came into ef-
                                 VDE 0170/0171, Parts 1 to 7,           Parliament and Council, dated         fect with a two-year transition
                                 designated as VDE regulations,         16.12.1999, the second impor-         period. This new directive had
                                 came into force on 01.05.1978.         tant directive concerning explo-      become necessary as a result
                                                                        sion protection, was published        of the approximation with other
                                                                        in the official gazette of the Eu-    EU directives, without revising
                                 The application of these Euro-         ropean communities. It con-           the technical content. On a na-
                                 pean standards for the con-            tains minimum requirements            tional level, this new ATEX di-
                                 struction and testing of explo-        for the improvement of the            rective was transposed in the
                                 sion-protected electrical              safety and health protection of       11th Regulation on the Product
                                 apparatus was governed                 employees potentially at risk         Safety Act. (ExVO –11. ProdSV).
                                 throughout Europe by the “EC           from explosive atmospheres.
                                 Directive 79/196/EC”. With the         This EC directive, also called
                                 new regulation, now known as           the European Occupational             As a result of the reform of na-
                                 ElexV, among other things this         Safety Directive, lays down the       tional and European regulations
                                 EC Directive was implemented           rules for operational explosion       (REACH regulation- 1907/2006/
                                 on 01.07.1980 and explosion pro-       protection and is aimed at the        EC, the Chemicals Act ChemG
                                 tection newly regulated for            operators of installations where      and the Occupational Safety Act
                                 manufacturers and operators.           explosion hazards are to be           ArbSchG,), it was also neces-
                                 Furthermore, the expertise of          expected.                             sary to review the Industrial
                                 the testing establishments and                                               Safety Regulation (BetrSichV)
                                 the design approval were re-                                                 with the set of Technical Regu-
                                 placed by a type sample test.          The directive was converted           lations on Industrial Safety
                                 The type sample test was car-          into national law on 03.10.2002       (TRBS) and the Ordinance on
                                 ried out by authorized testing         in the “Decree on health and          Hazardous Substances
                                 establishments of the member           safety protection relating to the     (GefStoffV) with the set of
                                 states of the EU (Notified Bod-        provision of work equipment           Technical Rules for Hazardous
                                 ies). The certificates of conform-     and the use thereof during op-        Substances TRGS.
                                 ity and inspection granted on          eration, safety during the opera-
                                 the basis of the said tests were       tion of installations requiring su-
                                 valid throughout Europe.               pervision and the organisation
                                                                        of operational safety provisions
                                                                        (Industrial Safety Regulation –

Explosion-protected electrical
equipment from the 60‘s                                              EATON                                                                        5
Principles of Ex-Protection - Basics - Crouse-Hinds
Principles of Explosion-Protection
1                         Physical principles of explosion-protection

Physical principles of explo-           Definition „Explosive atmos-
sion-protection                         phere“
                                        Mixture with air, under atmos-
Explosive mixture –                     pheric conditions, of flammable
explosive atmosphere                    substances in the form of gas,
§2 of the Ordinance on Hazardous        vapour, dust, fibres or flyings
Substances (GefStoffV) contains         which, after ignition, permits a
the following terms for explosive       selfsustaining propagation.
mixture / explosive atmosphere.
As these terms are not congruent
with the definitions according to       Standard atmospheric condi-
the standards/IEC (International        tions (relating to the properties
Electrotechnical Vocabulary),           of an explosive atmosphere) ac-
supplement the terms of the             cording to IEC 60079-0, the ba-
GefStoffV found there:                  sic standard for electrical equip-
                                        ment, and ISO 80079-36, the          Physical basics of an explosion
                                        basic standard for mechanical        plosion limits change: For exam-         grate quickly or, upon heat-
1.       An explosive mixture is a      equipment, are specified as fol-
         mixture of combustible                                              ple, as the proportion of oxygen         ing, explode when partially
                                        lows:                                increases, the upper explosive           confined.
         gases, vapours, mists or
         whirled up dust with air or    • Temperature –20 °C to +60 °C,      limit is raised. Generally, the ex-   2. oxidizing, if they are not
         another oxidizing agent,       • Pressure 80 kPa (0.8 bar) to       plosive limits are indicated in          normally inherently combus-
         whereby, after an ignition       110 kPa (1,1 bar) and              percent by volume. The percent           tible, but, in contact with
         source has become active,                                           by volume, abbreviated to %/vol.,        combustible substances or
                                        • air with normal oxygen content,    is the content by volume of the
         an automatic flame propa-                                                                                    preparations, mainly due to
                                          generally 21%/vol.                 combustible matter in the mix-
         gation, which generally in-                                                                                  the release of oxygen, they
         volves a sudden rise in        This limitation is necessary, as     ture with air. The lower explo-          enhance the fire hazard and
         temperature and pressure,      the essential safety parameters      sive limit of hydrogen is 4.0 %          the intensity of a fire consid-
         takes place.                   for explosion protection are a       by volume, and the upper explo-          erably
                                        function of the pressure, tem-       sive limit 75.6 % by volume.
2.       A dangerous explosive                                               The safety coefficients define        3. highly flammable, if:
                                        perature and oxygen content
         mixture is one which arises                                         quantitative data on the proper-         a) in a liquid state, they have
                                        and can only be considered to
         in such a quantity that spe-                                        ties of most of the known sub-           an extremely low flash point
                                        be sufficiently constant if they
         cial protective measures                                            stances                                  and a low boiling point,
                                        are within the limits of these
         are necessary for the main-                                                                                  b) in a gaseous state, they
                                        parameters. The methods for
         tenance of the health and                                                                                    are flammable in contact
                                        determining the safety parame-
         safety of workers or other                                          Flash point                              with air at ambient tempera-
                                        ters and the characteristics of
         persons.                                                            Combustible liquids are not the          ture and pressure.
                                        combustible substances are
3.       A dangerous explosive at-      based, among other things, on        actual combustion agent, but          4. highly flammable, if:
         mosphere is a dangerous        the standard series ISO/IEC          the vapours that develop above           a) they can become hot and
         mixture with air as the oxi-   80079-20.                            the liquid, when mixed with air,         finally catch fire in contact
         dizing agent under atmos-                                           form the explosive atmosphere.           with air at ambient tempera-
                                        A mixture is potentially explo-
         pheric conditions (ambient                                                                                   ture without any application
                                        sive if, under atmospheric con-
         temperature from -20 °C to                                          Definition „Flash point“:                 of energy,
                                        ditions, the concentration is
         +60 °C and pressure from                                                                                     b) in a solid state, they can
                                        within given, substance-specific     lowest liquid temperature at
         0.8 bar to 1.1 bar).                                                                                         readily catch fire after brief
                                        limits. Here distinction is made     which, under certain standard-
4.       A hazardous area is the                                                                                      contact with a source of igni-
                                        between the upper and lower          ized conditions, a liquid gives
         area in which a dangerous                                                                                    tion and continue to burn or
                                        explosion limit, whereby the         off vapours in quantity such as
         explosive atmosphere can                                                                                     to be consumed in a hazard-
                                        mixture is still combustible         to be capable of forming an ig-
         occur.                                                                                                       ous manner after removal of
                                        above the upper explosion limit.     nitable vapour/air mixture.
                                                                                                                      the ignition source,
                                                                             Hazardous substances and                 c) they have a very low flash
Combustible substance                                                        preparations are classified in
                                        Definition “Upper explosive                                                    point in a liquid state,
mixed with air                                                               accordance with their proper-
                                        limit (UEL)”                                                                  d) they develop highly flam-
The description of the physical                                              ties according to §3a, Clause 1          mable gases in dangerous
                                        Concentration of flammable gas
principles presupposes some                                                  of the Chemicals Act, i.a. as            quantities on contact with
                                        or vapour in air above which an
basic definitions which are de-                                              follows:                                 water or damp air.
                                        explosive atmosphere will not
rived, in part, from the norma-
                                        be formed.                           1. explosive, if, in a solid,         5. flammable, if they have a low
tive specifications. The Europe-
                                                                                liquid, pasty or gelatinous           flash point in a liquid state.
an regulations and the
                                                                                state, they may also react
associated national regulations         Definition “Lower explosive                                                 An explosive atmosphere that
                                                                                exothermically without at-
are also based on these specifi-        limit (LEL)“                                                               causes damage in the event of
                                                                                mospheric oxygen, thereby
cations. The definitions used in        Concentration of flammable gas                                             an explosion is called a “hazard-
                                                                                quickly evolving gases, and
explosion protection can be             or vapour in air below which an                                            ous explosive atmosphere”. It is
                                                                                which, under defined test
found in Chapter 426 of the IEV         explosive atmosphere will not                                              possible to roughly assess
                                                                                conditions, detonate, defla-
(IEC 60050), the International          be formed.
Electro-technical Vocabulary.
                                        Under conditions other than at-
                                        mospheric conditions, the ex-

     6                                                                 EATON                                         
Principles of Ex-Protection - Basics - Crouse-Hinds
Principles of Explosion-Protection
                                                                                      Physical principles of explosion-protection                        1
whether or not an atmosphere is         the simultaneous occurrence of a          Flames and hot gases
                                                                                                                         Mechanical sparks:
explosive. In confined spaces, re-      hazardous explosive atmosphere            (including hot particles)
                                                                                                                         friction; hammering; grinding
gardless of their size, a continu-      and an effective ignition source.         Flames are associated with
ous volume of 10 litres of explo-       Open flames and electric ignition         combustion reactions at temper-
sive atmosphere must already be         sources have always been con-             atures of more than 1000 °C.
regarded as hazardous. In the           sidered to be extremely critical          Hot gases are produced as reac-
case of smaller spaces with a           and the avoidance of these igni-          tion products and, in the case of
volume of
Principles of Ex-Protection - Basics - Crouse-Hinds
Principles of Explosion-Protection
1                       Physically principles of explosion-protection

                                                                             Ionizing radiation                    Note:
                                                                             Ionizing radiation can ignite ex-     In pressure lines of air compres-
                                                                             plosive atmospheres (especially       sors and in containers connect-
                                                                             explosive atmospheres with            ed to these lines, explosions
                                                                             dust particles) as a result of en-    can occur as a result of a com-
                                                                             ergy absorption. Ionizing radia-      pression ignition of lubricating
                                                                             tion can cause chemical decom-        oil mists e.g. by quick-acting
                                                                             position or other reactions,          valves in long pipes.
                                                                             which can lead to the genera-
                                                                             tion of highly reactive radicals or
                                                                             unstable chemical compounds.          Exothermic reactions, includ-
                                                                             This can cause ignition.              ing self-ignition of dusts
                                                                                                                   Exothermic reactions can act as
                                                                                                                   an ignition source if the rate of
                                                                             Ultrasound                            heat generation exceeds the
                                                                             When ultrasonic sound waves are       rate of heat loss to the sur-
                                                                             used, a large proportion of the       roundings. Whether a high
                                                                             energy emitted by the electro-        temperature can develop in the
                                                                             acoustic transducer is absorbed       event of a reaction is depend-
parts can easily lead to incentive     All conductive parts located in       by solid or liquid substances. As     ent, among other parameters,
sparks. With charged parts             the radiation field function as       a result, the substance exposed       on the volume/surface ratio of
made of non-conductive materi-         receiving aerials. If the field is    to ultrasonics heats up so in-        the reacting system, the ambi-
als, which include most plastics       powerful enough and if the re-        tensely that, in extreme cases,       ent temperature and the resi-
as well as some other materi-          ceiving aerial is sufficiently        ignition can be induced.              dence time. These high temper-
als, brush discharges and, in          large, these conductive parts                                               atures can lead to both the
special cases, during fast sepa-       can cause ignition in explosive                                             ignition of explosive atmos-
ration processes or due to a                                                 Adiabatic compression and
                                       atmospheres.                          shock waves                           pheres and the initiation of
combination of conductive and                                                                                      smouldering and/or burning.
non-conductive materials, prop-                                              In the case of adiabatic or almost
                                       The received radio-frequency
agating brush discharges are                                                 adiabatic compression and in
                                       power can, for example, make
also possible. Cone discharges                                               shock waves, such high tem-           Catalysers can also set off reac-
                                       thin wires glow or generate
from bulk material and cloud                                                 peratures can occur that explo-       tions where energy is released,
                                       sparks during the contact or in-
discharges can also occur.                                                   sive atmospheres (and deposit-        e.g. between hydrogen/air mix-
                                       terruption of conductive parts.       ed dust) can be ignited. The
Brush discharges can ignite                                                                                        tures and platinum, of alkaline
almost all explosive gas and           The energy picked up by the re-       temperature increase depends          metals with water, the self-igni-
vapour atmospheres.                    ceiving aerial, which can lead to     mainly on the pressure ratio,         tion of combustible dusts, the
                                       ignition, depends mainly on the       not on the pressure difference.       self-heating of animal fodder in-
                                       distance between the transmit-                                              duced by biological processes,
Lightning                              ter and the receiving aerial as                                             the decomposition of organic
If lightning strikes in an explosive   well as on the dimensions of                                                peroxides, or polymerization
atmosphere, ignition will always       the receiving aerial at a given                                             reactions.
occur. Moreover, there is also a       wavelength and high-frequency
possibility of ignition due to the     power.
high temperature attained by
lightning conductors. High cur-
rents flow from where the light-       Electromagnetic waves with
ning strikes and these currents        frequencies ranging from
can produce sparks in the vicinity     3 × 1011 Hz to 3 × 1015 Hz
of the point of impact. Even in        Radiation in this spectral range
the absence of lightning strikes,      can – in particular when fo-
thunderstorms can cause high           cussed - become a source of ig-
induced voltages in equipment,         nition due to absorption in ex-
protective systems and                 plosive atmospheres or on solid
components.                            surfaces. Sunlight, for example,
                                       can trigger an ignition if objects
                                       cause a convergence of the ra-
Electromagnetic waves with             diation. In the case of laser radi-
frequencies ranging from               ation, even at great distances
104 Hz to 3 x 1012 Hz (high            the energy or power density of
frequency)                             even an unfocused beam can
Electromagnetic waves are              be so great that ignition is
emitted by all systems that gen-       possible. Here, too, the process
erate and use high-frequency           of heating up occurs mainly
electrical energy (high-frequen-       when the laser beam strikes a
cy systems), e.g. radio transmit-      solid body surface or when it is
ters or industrial or medical RF       absorbed by dust particles in
generators for heating, drying,        the atmosphere or on dirty
hardening, welding, cutting, etc.      transparent parts.                    Impact of a dust explosion: Rolandsmühle, Bremen, Germany

 8                                                                      EATON                                        
Principles of Explosion-Protection
                                                               Primary and secondary explosion-protection concepts                           1
Primary and secondary explo-        Prevention of an ignition             the case of liquid substances,         nical means is that it needs
sion-protection concepts            Here distinction is made be-          the concentration is usually           constant servicing and monitor-
Explosion protection measures       tween two procedures:                 kept below the lower explosive         ing. In addition to this, precau-
shall always be taken if the for-                                         limit, since a large amount of ef-     tions have to be taken in case
mation of a hazardous explosive                                           fort is required to keep the con-      the installation should operate
                                    • Raising the flash point
atmosphere is to be expected                                              centration in the upper range.         at a lower output or fail alto-
and, at the same time, an igni-     Here the flash point of a flam-                                              gether.
tion source with sufficient ener-   mable liquid shall be at least 5 K
                                                                          • Inertisation
gy is present. In accordance        to 15 K above the processing or                                              Secondary explosion
                                    room temperature. In the case         If the proportion of oxygen in a
with Directive 2014/34/EU, the                                                                                   protection
                                    of water soluble, flammable           mixture is less than 10 % by
measures are divided into pri-                                                                                   Once all the possibilities of pri-
                                    substances this can be                volume, then, as a general rule,
mary, secondary and tertiary                                                                                     mary explosion protection have
                                    achieved by adding water.             a mixture is not explosive. In or-
measures.                                                                                                        been exhausted, there can still
                                                                          der to attain such a low propor-
                                                                          tion, so-called inert gaseous          be areas where a hazardous ex-
                                                                          substances such as nitrogen,           plosive atmosphere occurs.
                                                                          carbon dioxide, water steam or         These areas are called hazard-
                                                                          halogenated hydrocarbon are            ous areas. Here secondary ex-
                                                                          added to the mixture until the         plosion protection with protec-
                                                                          desired concentration is ob-           tive measures that render
                                                                          tained. If the percent by volume       ignition sources ineffective are
                                                                          of the inert gas to the flamma-        applied. All the types of protec-
                                                                          ble gas is in the minimum ratio        tion described in the standards
                                                                          of 25:1, an explosive atmos-           of the series IEC 60079-0ff for
                                                                          phere cannot form, regardless          electrical equipment and ISO/
                                                                          of the quantity of air added.          IEC 80079-36ff for mechanical
                                                                                                                 equipment are secondary explo-
                                                                                                                 sion protection measures.
                                                                          • Ventilation
                                                                          The formation of a hazardous
                                                                                                                 Constructional (tertiary)
                                                                          explosive atmosphere can be
                                                                                                                 explosion protection
                                                                          prevented or restricted by venti-
                                                                          lation. In rooms above ground          If, in spite of the measures
                                                                          level and without special venti-       named above, ignition sources
                                                                          lation, the air is generally re-       and, as a result, explosions are
                                                                          newed by natural ventilation           to be expected, e.g. due to
                                                                          once per hour. By way of com-          electrostatic discharges or
                                                                          parison, the exchange of air in        chemical reactions, construc-
                                                                          cellar rooms takes up to 2.5           tional or tertiary explosion pro-
                                                                          hours. The concentration of the        tection measures shall be tak-
                                                                          mixture can, however, only be          en.
Primary explosion protection
                                    • Lowering the processing             calculated if the escaping quan-
The avoidance of a hazard is al-      temperature                         tity per unit of time of a flam-       The explosion-protected design
ways better than any protection
                                    With this method it is neces-         mable substance is known and           is, for example, a constructional
method. Among other things, it
                                    sary to apply technical meas-         if an equal distribution can be        measure that cannot prevent an
is possible to prevent an explo-
                                    ures (e.g. cooling) to ensure         assumed.                               explosion, but can limit the ef-
sion by excluding the formation
of an explosive atmosphere. Pri-    that the processing tempera-                                                 fects to a nonhazardous degree.
mary explosion protection can,      ture is always at least 5 - 15 K                                             The equipment shall be de-
                                                                          The natural flow conditions in a
for example, be achieved by ap-     lower than the flash point. It is,                                           signed in such a way that it can
                                                                          room can be assessed by an ex-
plying the following measures:      however, necessary to keep                                                   withstand the maximum explo-
                                                                          pert on ventilation, who will
                                    faults, standstills, leakages and                                            sion pressure and, in extreme
                                                                          then usually recommend venti-
                                    other influence factors safely                                               cases, even the detonation
Avoidance of flammable                                                     lation by technical means, as
                                    under control.                                                               pressure. A detonation can hap-
substances                                                                the natural ventilation cannot be
                                                                          considered to be a constant.           pen quickly in pipes and elon-
Whenever possible, flammable
                                    Limitation of the concentration       Compared to natural ventilation,       gated constructions. If the
substances should be substitut-
                                    The formation of an explosive         it ensures the exchange of larg-       flameproof design is not able to
ed by substances that are not
                                    atmosphere can be prevented if        er quantities of air and a more        withstand the increase in pres-
capable of forming an explosive
                                    it is possible to limit the con-      carefully directed air flow.           sure, effective explosion pres-
                                    centration of a substance to the      Moreover, the concentration oc-        sure relief measures shall be
                                    range below the lower or above        curring can be determined with         taken.
                                    the upper explosive limit. This is    a considerably higher degree of
                                    often possible with gases.            reliability. With technical ventila-
                                    However, problems arise if            tion, gas clouds that are re-
                                    there is a gas leak or if the igni-   leased due to faults can be
                                    tion range has to be passed           quickly diluted to non-critical
                                    through when starting up or           values. On the other hand, the
                                    closing down the installation. In     drawback of ventilation by tech-                                                 EATON                                                                        9
Principles of Explosion-Protection
1                      Hazardous areas

Hazardous areas                           probability of the occurrence of    The international definition of      Zone 20
                                          an explosive atmosphere.            zones is given in EN 60079-10.       • Area in which an explosive at-
Definition                                 In addition, distinction is made    For this reason, both defini-          mosphere in the form of a
An area in which an explosive             between flammable gases, va-        tions, which are almost identi-        cloud of combustible dust in
atmosphere is present, or may             pours and mists on the one          cal, are stated below.                 air is present continuously, or
be expected to be present in              hand, and combustible dusts on                                             for long periods or frequently
quantities such as to require             the other. Information on the       Zone 0                                 (EN 60079-10-2).
special precautions for the con-          zone classification can also be     • Area in which an explosive at-     • An area in which a hazardous
struction, installation and use of        found in the Explosion-Protec-        mosphere consisting of a             explosive atmosphere in the
electrical apparatus                      tion Rules of the Employers’          mixture of air with flammable        form of a cloud of combusti-
(IEV 426-03-01).                          Liability Insurance Association       substances in the form of            ble dust in the air is present
                                          for the Chemical Industry and         gas, vapour or mist is present       continuously, for long periods
                                          EN 60079-10.                          continuously or for long peri-       or frequently (GefStoffV).
                                                                                ods or frequently
A hazardous area is a                                                           (EN 60079-10-1).
                                          Classification of hazardous                                               Zone 21
three-dimensional region
                                          areas                               • An area in which a hazardous       • Area in which an explosive at-
or space (EN 60079-14).
                                          In national law the definition of     explosive atmosphere con-            mosphere in the form of a
                                          zones given in the Ordinance          sisting of a mixture of air and      cloud of combustible dust in
Zone classification                        on Hazardous Substances               flammable gases, vapours or          air is likely to occur occasion-
In accordance with Directive              (GefStoffV) applies.                  mists is present continuous-         ally in normal operation
1999/92 EG, hazardous areas                                                     ly, over long periods or fre-        (EN 60079-10-2).
are divided into six zones. The                                                 quently (GefStoffV).
                                                                                                                   • An area in which a hazardous
classification is based on the                                                                                       explosive atmosphere in the
                                                                              Zone 1                                 form of a cloud of combusti-
                                                                              • Area in which an explosive           ble dust in the air can only
                                                                                gas atmosphere consisting of         form occasionally during nor-
                                                                                a mixture of air with flamma-        mal operation (GefStoffV).
Gas-Ex-areas                                                                    ble substances in the form of
                                                                                gas, vapour or mist is likely to   Zone 22
                                                                                occur in normal operation oc-
         Fuel tank                                                                                                 • Area in which an explosive at-
                                                                Zone 2          casionally (EN 60079-10-1).
                                                                                                                     mosphere in the form of a
                                                                              • An area in which a hazardous         cloud of combustible dust in
                                                                                explosive atmosphere con-            air is not likely to occur in nor-
                                                                                sisting of a mixture of air and      mal operation, but, if it does
                                                                                flammable gases, vapours or          occur, it will persist for a
                         Zone 0                                                 mists can form during normal         short period only
                                                                                operation (GefStoffV).               (EN 60079-10-2).

                                               Zone 1                         Zone 2
                       flammable liquid                                                                            • Area in which an explosive at-
                                                                              • Area in which an explosive
                                                                                                                     mosphere in the form of a
                                                                                gas atmosphere consisting of
                                                                                                                     cloud of combustible dust in
                                          Tank Flange/Pump/Piping               a mixture of air with flamma-
                                                                                                                     air does not normally occur; if
                                                                                ble substances in the form of
                                                                                                                     it occurs, then only rarely and
Example of the zone classification of explosive gas atmospheres to               gas, vapour or mist is not like-
                                                                                                                     for a short time (GefStoffV).
EN 60079-10-1                                                                   ly to occur in normal opera-
                                                                                tion, but if it does occur, will
                                                                                persist for a short period only    Note:
Dust-Ex-Areas                                                                   (EN 60079-10-1).                   Layers, deposits and accumula-
                                                                              • An area in which a hazardous       tions of combustible dust are to
        Sack emptying station                                                   explosive atmosphere con-          be considered in the same way
                                                          Zone 22               sisting of a mixture of air and    as any other source that forms
                                                                                flammable gases, vapours or        an explosive atmosphere.
                                                                                mists does not normally oc-        Normal operation is understood
                                                                                cur, and if it occurs, then only   as being the state where instal-
                        Zone 21
                                                                                rarely and for a short time        lations are being used within
                                                                                (GefStoffV).                       their design parameters.
                                   Zone 20

Example of the zone classification of explosive dust atmospheres to
EN 60079-10-2

 10                                                                      EATON                                        
Principles of Explosion-Protection
                                                                                                             Gas-Ex-areas                   1
Examples of applications           can usually accommodate these
                                                                                                                                   Zone 2
and the classification of           explosive gases for longer peri-
suitable equipment:                ods, so that it is also necessary                Zone 1
Gas-Ex-areas                       to expect a Zone 0 area here.
                                   With equipment for Zone 0, ig-
Gas-Ex-areas                       nition sources shall be protect-
                                   ed against explosion even if the
Zone 0                             occurrence of failures is only
Zone 0 mainly encompasses ar-      rare. Hence, the equipment
eas such as the inside of en-      shall satisfy the following re-
closed containers, pipes and ap-   quirements:
paratus that contain flammable     Should one type of protection
liquids.                           fail or should two faults occur
Here the respective operating      simultaneously, sufficient pro-
temperature lies above the         tection against explosion shall
                                                                       Zone classification example: Loading/discharging flammable liquids
flash point. The hazardous area    still be ensured.
                                                                       from a road transporter tanker without stand-alone ventilation.
is above the surface of the liq-   The constructional require-
uid and not in the liquid. Most    ments DIN EN 60079-26 (VDE
gases of flammable liquids are     0170/0171/Part 12-1) state that     type of protection “ia” to EN           The chapter „Electrical equip-
heavier than air and spread in a   the necessary explosion protec-     60079-11, Intrinsic Safety, or          ment for use in hazardous are-
similar way to liquids. Cavities   tion is attained if the equipment   satisfies the requirements of           as” describes the individual
such as pits or pump sumps         is built in accordance with the     two types of protection of the          types of protection. According to
                                                                       series EN 60079, which are ef-          Directive 2014/34/EU, Zone 1
                                                                       fective independently of each           equipment shall satisfy the
                                                                       other.                                  requirements for Category 2G.
                                                                       For this reason, for example,
                                                                       flameproof luminaires were ad-          Zone 2
                                                                       ditionally pressurised or intrinsi-     Zone 2 encompasses areas
                                                                       cally safe apparatus in the type        around Zone 0 and Zone 1, as
                                                                       of protection “ib” potted.              well as areas around flanged
                                                                       According to Directive                  joints on pipes in enclosed
                                                                       2014/34/EU, equipment for               rooms. Furthermore, it includes
                                                                       Zone 0 shall satisfy the require-       such areas in which, due to
                                                                       ments for Category 1G. In Zone          natural or forced ventilation,
                                                                       0 the hazard of an ignition due         the lower explosive limit is only
                                                                       to electrostatic charges, even          attained in exceptional cases,
                                                                       on rare occasions, shall be safe-       such as the environment of
                                                                       ly excluded. For this reason, the       outdoor installations. Flamma-
                                                                       requirements according to EN            ble or explosive substances are
                                                                       60079-0 for equipment for use           manufactured or stored in Zone
                                                                       in Zone 0 exceed those for              2. The probability of the occur-
                                                                       equipment for Zone 1 by far.            rence of an ignitable concentra-
                                                                                                               tion is rare and, if one occurs, it
                                                                                                               only persists for a short period.
                                                                       Zone 1
                                                                       Flammable or explosive sub-
                                                                                                               During normal, trouble-free op-
                                                                       stances are made, processed or
                                                                                                               eration, ignition sources shall
                                                                       stored in Zone 1. This includes
                                                                                                               be safely prevented.
                                                                       the proximity of loading flap or
                                                                       filling and discharging facilities,
                                                                       the vicinity of fragile equipment,      According to Directive 2014/34/EU,
                                                                       pipes and glands on pumps and           equipment for Zone 2 shall sat-
                                                                       slides that do not seal ade-            isfy the requirements for Cate-
                                                                       quately. It is likely that an ignit-    gory 3G. In addition, all equip-
                                                                       able concentration will occur           ment that satisfies the
                                                                       during normal operation.                requirements for equipment for
                                                                                                               use in Zone 0 and Zone 1 is, of
                                                                                                               course, permitted.
                                                                       Ignition sources that occur dur-
                                                                       ing normal, trouble-free opera-
                                                                       tion and those that usually oc-
                                                                       cur in the event of operating
                                                                       disturbances shall be safely

Example for a Zone 0 application: The inside of a flat-bottom tank
of an oil terminal                                              EATON                                                                         11
Principles of Explosion-Protection
1                      Dust-Ex-areas

Dust-Ex-Areas                        Zone 21
                                     Among others, Zone 21 encom-
                                     passes mills, warehouses for
                                     coal or grain, and the area sur-
                                     rounding filling stations. Here,
                                     for example, explosive clouds
                                     of dust can develop due to the
                                     occasional escaping of dust
                                     from the opening. The risk of
                                     hazards due to dust deposits is
                                     often underestimated.

                                     Explosive dust/air mixtures can
Zone 20
                                     develop due to the formation of
Zone 20 mainly encompasses           a smoulder spot or of a low
areas inside closed containers,      temperature carbonization gas,
pipes and apparatus in which         as well as due to the deflagra-
combustible dust in the form of      tion of a low temperature car-
a cloud is present continuously      bonization gas or the whirling-
or for long periods or frequently.   up of dust caused by glowing
With equipment for Zone 20, ig-      combustion.
nition sources shall be protect-
ed against explosions, even if
the occurrence of a malfunction      Ignition sources that occur dur-   Example of dust-Ex-Zone 21: Explosion-protected terminal box
is rare. For this reason, equip-     ing normal, trouble-free opera-
ment shall fulfil the following      tion and those that normally oc-   Zone 22
requirement:                         cur in the event of malfunctions   In Zone 22, under normal oper-
                                     shall be safely prevented.         ating conditions it is unlikely
In the event of the failure of one                                                                          According to Directive 2014/34/
type of protection or the simul-                                        that an explosive dust/air mix-     EU, equipment for Zone 22 shall
taneous occurrence of two mal-                                          ture will occur. An explosive at-   satisfy the requirements for
                                     The individual types of protec-    mosphere is only to be expect-
functions, it is necessary to        tion are described in the chap-                                        Category 3D.
ensure adequate explosion pro-                                          ed in the event of malfunctions,
                                     ter „Electrical equipment for      e.g. due to whirled-up dust.
tection. According to Directive      use in hazardous areas“. Accord-                                       Detailed information on all
2014/34/EU, equipment for use        ing to Directive 2014/34/EU                                            zones can be found in the
in Zone 20 shall satisfy the re-     equipment for Zone 21 shall        Ignition sources shall be safely    chapter “Installation and
quirements for Category 1D.          satisfy the requirements for       prevented during normal, trou-      operation of electrical
                                     Category 2D                        ble-free operation.                 installations in hazardous areas”.

 12                                                               EATON                                       
European Ex-Directives
                                                                                                European Ex-Directives                   2
                                                                          This directive, which applied to     type and content of the con-
                                                                          both electrical and mechanical       formity assessment procedure.
                                                                          equipment, encompassed re-           Thus, for example, an EC Type
                                                                          quirements relating to the ap-       Examination Certificate accord-
                                                                          proval of equipment and the          ing to Directive 94/9/EC can be
                                                                          requisite quality assurance sys-     used to issue a new CE Decla-
                                                                          tems. These requirements are         ration according to Directive
                                                                          graduated according to the           2014/34/EU. In accordance with
                                                                          equipment category.                  Article 41, § 2, the issue of a
                                                                                                               new EU Type Examination
                                                                                                               Certificate according to the new
                                                                          As this new directive was            directive is not necessary.
                                                                          drawn up according to the
                                                                          “new approach” of the EC, it         Directive 94/9/EC could be ap-
                                                                          also introduced the Declaration      plied for the last time on
                                                                          of Conformity to be issued by        19.04.2016. As of 20.04.2016
                                                                          the manufacturer for explosion-      only the new ATEX directive
                                                                          protected equipment and the          2014/34/EU applies.
European Ex-Directives               This symbol was specified as
                                     the distinctive mark for the plac-   CE marking of products.
Free movement of goods               ing of explosion-protected elec-
within the European                  trical equipment on the market       Directive 2014/34/EU of the
Community                            throughout the community:            European Parliament and
                                                                          Council dated 26.02.2014 –
Article 100 of the treaty estab-                                          2nd ATEX Directive
lishing the EEC (European
Economic Community) was the                                               Directive 94/9/EC had to be
basis for the free movement of                                            adapted to Resolution No.
goods within the European                                                 768/2008/EC. This resolution
economic area. In 1975, to im-                                            required a common legal frame-
plement this article, the Council                                         work for the marketing of prod-
of the European Community                                                 ucts and contains general prin-
issued the Explosion Protection                                           ciples and reference provisions
Framework Directive                                                       that are to be applied in all sec-
(Directive 76/117/EEC).              Directive 94/9/EC of the             tor-specific legal acts. It was,
The issue of                         European Parliament and              therefore, a common basis for a
Directive 79/116/EEC by the          Council dated 23.03.1994 -           revised or new version of exist-
European Commission                  1st ATEX Directive                   ing legal provisions.
concretised this basis and
established a first legal basis.
                                     The purpose of this directive
A series of European standards                                            This new ATEX directive came
                                     was the approximations of the
for explosion- protected appara-                                          into effect on 20.04.2014, with
                                     laws of the member states of
tus was drawn up by the Euro-                                             a two-year transitional period.
                                     the European Union for equip-
pean Standards Committee for                                              However, this did not mean
                                     ment and protective systems
electrical apparatus (CENELEC)                                            that, as was the case with the
                                     intended for use in potentially
to provide the basis for the en-                                          transition to the 1st ATEX direc-
                                     explosive atmospheres. As of
forcement of the requirements.                                            tive, both directives could be
                                     01.07.2003 it replaced all previ-
In Germany these European                                                 applied simultaneously. On the
                                     ous directives on explosion pro-
standards, EN 50014 to EN                                                 part of the European Commis-
                                     tection on a European level.
50020, were adopted as VDE                                                sion only a legal certainty was
                                     The directive, also known as         provided that, when the transi-
standards in the national stand-
                                     the ATEX directive, applied to       tion period expired, the new di-
                                     equipment and protective sys-        rective only in the announced
                                     tems that were intended for          form was to be applied. Thus,
Directive 79/196/EEC was re-         use in potentially explosive at-     the manufacturers were given
stricted to explosion-protected      mospheres. Safety devices and        the opportunity to adapt their di-
electrical equipment and the         control systems for use outside      rective-specific documents and
regulations that were required       of potentially explosive atmos-      papers within this two year pe-
for the free movement of             pheres also came under this di-      riod. In the case of the notified
goods.                               rective. This also applied when      bodies, this meant, for exam-
                                     such devices were required for       ple, that they had to complete
                                     the safe operation of equipment      the designation procedure for
By strict reference to the Euro-     and protective systems in haz-       the new ATEX directive within
pean standards, the normative        ardous areas or contributed to       these two years. The major
basis for the certification of ex-   it, Furthermore, the directive       changes only concern formal
plosion-protected electrical ap-     now directly included “funda-        and legal aspects. No changes
paratus was regulated by “noti-      mental safety requirements“ for      were made to the basic health
fied bodies”.                        explosion-protected equipment.       and safety requirements or the                                                 EATON                                                                   13
European Ex-Directives
2                      ATEX directive 2014/34/EU

ATEX Directive 2014/34/EU             • means of transport, i.e.
Directive 2014/34/EU applies to         vehicles and their trailers in-
products, i.e. equipment and            tended solely for transporting
protective systems intended for         passengers by air or by road,
use in potentially explosive at-        rail or water networks, as
mospheres, with the following           well as means of transport in       Structure and content of Directive 2014/34/EU
definitions, which are new in           so far as such means are de-        • Chapter 1
part:                                   signed for transporting goods         General Provisions (Article 1-5)
                                        by air, by public road or rail      • Chapter 2
a) “Equipment” means
                                        networks or by water. Vehi-           Obligations of economic operators (Article 6-11)
machines, apparatus, fixed or
                                        cles intended for use in a po-
mobile devices, control compo-                                              • Chapter 3
                                        tentially explosive atmos-
nents and instrumentation                                                     Conformity of the product (Article 12-16)
                                        phere shall not be excluded
thereof and detection or pre-
                                        from the scope of this Direc-       • Chapter 4
vention systems which, sepa-
                                        tive.                                 Notification of conformity assessment bodies
rately or jointly, are intended for
                                                                              (Article 17-33)
the generation, transfer, stor-
age, measurement, control and         d) “making available on               • Chapter 5
conversion of energy and/or the            the market” means                  Union market, surveillance and control of products entering
processing of material and            any supply of a product for dis-        the Union market and Union safeguard procedure
which are capable of causing an       tribution, consumption or use           (Article 34-38)
explosion through their own po-       on the Union market in the
                                                                            • Chapter 6
tential sources of ignition.          course of a commercial activity,
                                                                              Committee, transitional and final provisions
                                      whether in return for payment
b) “Protective systems” means                                                 (Article 39-45)
                                      or free of charge;
devices other than components                                               • Annex I
of equipment which are intend-        e) “placing on the market”
                                                                              Criteria determining the classification of equipment
ed to halt incipient explosions           means
                                                                              groups into categories
immediately and/or to limit the       the first making available of a
effective range of an explosion       product on the Union market;          • Annex II
and which are separately made                                                 Essential health and safety requirements relating to the
                                      f) “manufacturer”’ means
available on the market for use                                               design, and construction of equipment and protective
                                      any natural or legal person who         systems for use in potentially explosive atmospheres
as autonomous systems.
                                      manufactures a product or has
c) “Components” means                                                       • Annex III
                                      a product designed or manufac-
any item essential to the safe                                                Module B: EU-Type Examination
                                      tured, and markets that product
functioning of equipment and          under his name or trade mark or       • Annex IV
protective systems but with no        uses it for his own purposes.           Module D: Conformity to type based on quality
autonomous function.                                                          assurance of the production process
This Directive shall not apply to:                                          • Annex V
• medical devices intended for                                                Module F : Conformity to type based on
  use in a medical environ-                                                   product verifications
  ment;                                                                     • Annex VI
• equipment and protective                                                    Module C1: Conformity to type based on internal
  systems where the explosion                                                 production control plus supervised product testing
  hazard results exclusively                                                • Annex VII
  from the presence of                                                        Module E: Conformity to type based on product
  explosive substances                                                        quality assurance
  or unstable chemical
                                                                            • Annex VIII
                                                                              Module A: Internal production control
• equipment intended for use
                                                                            • Annex IX
  in domestic and non-com-
                                                                              Module G: Conformity based on unit verification
  mercial environments where
  potentially explosive atmos-                                              • Annex X
  pheres may only rarely be                                                   EU Declaration of Conformity
  created, solely as a result                                               • Annex XI
  of the accidental leakage of                                                Part A: Repealed Directive with a list of the successive
  fuel gas;                                                                   amendments thereto (referred to in Article 43)
• personal protective                                                       • Part B: Time limits for transposition into national law and
  equipment as covered by                                                     dates of application (referred to in Article 43)
  Directive 89/686/EEC;
                                                                            • Annex XII
• seagoing vessels and mobile                                                 Correlation table
  offshore units together with
  equipment on board such
  vessels or units;

 14                                                                 EATON                                       
European Ex-Directives
                                                                                             ATEX directive 2014/34/EU                                       2
Essential health and safety            Equipment groups and                  Classification of explosion protected apparatus in equipment
requirements                           equipment categories                  groups and categories according to 2014/34/EU
The requirements relating to           Equipment is subdivided into
equipment and protective devic-        groups and categories:                Equipment Group I for mines endangered by firedamp.
es are divided up into general                                               The equipment Group I is subdivided into the Categories
requirements and supplementa-                                                M1 and M2:
                                       • Equipment group I – applies
ry requirements, whereby, above          to equipment intended for
all, the supplementary require-          use in underground parts of                  The equipment in this category is intended for use in both underground
ments are to take both existing          mines as well as those parts                 parts of mines and those parts of surface installations of such mines
and potential hazards into con-          of surface installations of                  that are endangered by firedamp and/or combustible dust.
sideration. This means that the          such mines that can be en-
equipment and protective sys-            dangered by firedamp and/or                  The equipment shall continue to remain functional even in the event of
tems shall satisfy one or more           combustible dust.                      M1    rare incidents relating to the equipment with an explosive atmosphere
requirements at the same time,                                                        present, and feature such protective measures that in the event of fail-
                                       • Equipment group II – applies                 ure of one means of protection, at least an independent second means
inasmuch as this is necessary
                                         to equipment for use in the                  provides the requisite level of protection, or the requisite level of protec-
for their correct operation or
                                         remaining areas that can be                  tion is assured in the event of two faults occurring independently of
their intended use.
                                         at risk due to an explosive at-              each other.
Adherence to the health and              mosphere.
safety protection requirements
is absolutely essential to guar-       Categories
antee the safety of equipment                                                         The equipment in this category is intended for use in both underground
                                       See adjacent tables
and protective devices. These                                                         parts of mines and those parts of surface installations of such mines that
requirements shall be imple-                                                          are endangered by firedamp and/or combustible dust.
mented with prudence in order          Making available on the mar-
to fulfil the latest technological     ket and commissioning                    M2    If an explosive atmosphere occurs, it must be possible to switch off the
developments at the time of            of products                                    equipment. The constructional explosion-protection measures ensure the
making equipment available on          The member states must not                     required degree of safety during normal operation, even under severe oper-
the market. This directive only        forbid, restrict or impede the                 ating conditions and, in particular, in cases of rough handling and changing
                                                                                      environmental influences.
defines general basic require-         making available on the market
ments. In order to make it easi-       and commissioning of equip-
er to furnish proof that a piece       ment, protective systems and
of equipment or a protective           devices that conform to the
system conforms to these re-           terms of this directive. Similarly,   Equipment Group II for all other hazardous areas
quirements, uniform standards          the making available on the mar-      The equipment Group II is subdivided into the
have been established on a Eu-         ket of components accompanied         Categories 1, 2 and 3:
ropean level. If standards are         by a certificate of conformity
published by the European              according to Article 13, § 3 of
Commission in the Official Ga-         Directive 2014/34/EU shall not                 The equipment in this category is intended for use in areas in which an
zette of the European Commu-           be forbidden, restricted or im-                explosive atmosphere is present continuously or for long periods or fre-
nities as assigned to a given di-      peded if they are to be built into
rective, they are                      a piece of equipment or a pro-
                                                                                      Even if equipment failures only occur infrequently, the equipment must
valid as so-called “harmonized         tective system in line with this               ensure the required degree of safety and feature such explosion protec-
standards”.                            directive.                               1     tion measures that
If a product meets the require-
ments of the harmonized stand-                                                        •     if one constructional protective measure fails, at least one other
                                       The EU member states assume                          independent constructional protective measure ensures the
ards, the essential require-           conformity with this directive                       required degree of safety, or
ments of the directive are             and with the conformity assess-                •     if two independent faults occur in combination, the required
deemed to be fulfilled                 ment procedures if the appara-                       degree of safety is still ensured.
(presumption of conformity). If        tus, protective systems and de-
necessary, this list in the official   vices are accompanied by the
gazette is adapted in line with        EU Certificate of Conformity
the latest versions of the stand-      and if the products are provided
ards. These standards are, in                                                         The equipment in this category is intended for use in areas in which an
                                       with the CE marking.                           explosive atmosphere occurs occasionally. Even in the case of frequent
principle, prepared by the Euro-
                                                                                2     equipment failures or faulty conditions that are normally to be expected,
pean Committee for Standardi-
                                                                                      the constructional explosion-protection measures ensure the required
zation (CEN) and the European          Products that do not yet meet                  degree of safety.
Committee for Electro-technical        the requirements of this direc-
Standardization (CENELEC).             tive may be displayed at exhibi-
In the field of explosion protec-      tions, fairs and demonstrations
tion the standardization is large-     if a visible sign clearly indicates
ly carried out by Technical Com-       that it will not be possible to                The equipment in this category is intended for use in areas in which no
                                       purchase the product until com-                occurrence of an explosive atmosphere due to gases, vapours, mists or
mittee TC31, “Equipment for
                                       pliance with the directive has           3     whirled-up dust is to be expected. If, however, it occurs, then in all prob-
explosive atmospheres”, of the
                                       been ensured.                                  ability only rarely or for a short period. During normal operation the equip-
International Electro-technical                                                       ment ensures the required degree of safety.
Commission (IEC).                                                    EATON                                                                                       15
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