Principles of Ex-Protection - Basics - Crouse-Hinds
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Basics Principles of Ex-Protection
The safety you rely on.
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in high consequence harsh and hazardous
environments
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The Eaton advantage.
Crouse-Hinds series remains the brand that stands And now, the next phase in the evolution of the
for safety in the harshest of environments when brand you trust: Crouse-Hinds joins the leading
power management is most critical. While it all Eaton portfolio of reliable, efficient and safe
began with the Condulet®, the Crouse-Hinds electrical power management solutions.
brand has grown into the premier name for a
comprehensive portfolio of solutions for high- More protection. More technology.
consequence harsh and hazardous environments. Expect more.
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
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
Explosion-Protected Solutions Global Support &
- Worldwide- Manufacturing
With the brand of CEAG we develop and Our sales support and manufacturing facilities
manufacture electrical products that provide are strategically positioned around the world to
safety, productivity, innovation and labour deliver products close to your project. Whenever
savings in hazardous, industrial and commercial required we are there on-site during construction,
environments - for more than 100 years. commissioning and training.
We design, configure and manufacture explosion- Eaton’s Crouse-Hinds Division manufactures in
protected electrical equipment for your safety. 5 continents and sells into more than 100
Of course we are certified for all functional areas countries. We have dedicated sales support in
according to the latest quality standards every major location with local technical sales and
ISO 9001:2015 and in addition for the necessary engineering teams to support your immediate
explosion protection according to ISO/IEC 80079-34. needs. As one of the largest oil & gas bulk
We will implement consistently your specifications electrical and instrument material suppliers, we
according to current national directives and stand- can easily provide you a single source for all the
ards at the application site. components to complete your project on time and
on budget.
In addition to systems and components built to
ATEX Directive 2014/34/EU and European
Standards, we also provide products with
international approvals like IECEx (IEC Ex Scheme),
UL and CSA (USA, Canada), INMETRO (Brazil) and
NEPSI (China) as well as certifications of Eastern
Europe testing and certification organisations and
the new TR-CU Customs Union (EAC).
2 EATON www.crouse-hinds.de
Preface
0
Preface
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.
(https://www.crouse-hinds.de/
de/seminar-explosionsschutz/)
www.crouse-hinds.de EATON 3
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-
Ex
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 www.crouse-hinds.de
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 –
BetrSichV)”.
Explosion-protected electrical
equipment from the 60‘s
www.crouse-hinds.de EATON 5
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 www.crouse-hinds.de
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 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 www.crouse-hinds.dePrinciples 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-
mixture.
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-
www.crouse-hinds.de EATON 9Principles 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).
Note:
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-
Valve
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 www.crouse-hinds.dePrinciples 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
prevented.
Example for a Zone 0 application: The inside of a flat-bottom tank
of an oil terminal
www.crouse-hinds.de EATON 11Principles 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 www.crouse-hinds.deEuropean 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-
ards.
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
www.crouse-hinds.de EATON 13European 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
substances;
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 www.crouse-hinds.deEuropean 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-
quently.
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).
www.crouse-hinds.de EATON 15You can also read
