Explosion Protection - The Basics

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    explosion protectionThe basics of

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    prefaceIt is a fact that gases, vapours and mists escape during the production, processing,

    transportation and storage of flammable substances in the chemical and petrochemical

    industries, as well as in the production of mineral oil and natural gas, in mining and in

    many other sectors. During many processes, especially in food industries, combustible

    dusts are also created. These flammable gases, vapours, mists, and dusts form an explosive

    atmosphere with the oxygen in the air. If this atmosphere is ignited, explosions take place,

    which can result in severe harm to human life and property. To avoid the danger of

    explosions, protective specifications in the form of laws, regulations, and standards have

    been developed in most countries, which are aimed at ensuring that a high level of safety is

    observed. Due to the growing international economic link, extensive progress has

    been made in harmonizing regulations for explosion protection. The conditions for a

    complete harmonization were created in the European Union by the 94/9/EC and 99/92/EC

    Directives. However, there is still much to be done in this area world-wide. The aim of

    this brochure is to provide both experts and interested laymen with an overview of the field

    of explosion protection, in conjunction with electrical apparatus and installations. It does

    not replace the study of the relevant statutory regulations and applicable standards.

    In mining, miners underground have always lived under the threat of firedamp explosions.

    Herein lies the origins of explosion protection, which has been consistently developed

    in industrialized countries, and which now provides a high level of safety.

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    Explosion Protection in North America

    6.1 Introduction

    6.2 Classification of Hazardous Locations

    6.3 Regulations for Installation

    6.4 Constructional Requirements

    6.5 Degrees of Protection provided by Enclosures

    6.6 Certification and MarkingAppendix

    7.1 Comparison of IEC Publications and European Standards (EN)

    7.2 Safety Ratings of Flammable Gases and Vapours

    7.3 Classification of Hazardous Locations in North America

    7.4 Constructional Requirements for Explosion ProtectedElectrical Equipment

    7.5 Degrees of Protection according to IEC 60 529 IPXX

    7.6 Degrees of Protection according to NEMA StandardsLiterature

    Adresses9

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    2. the basic physic principles and definitexplosion protection

    2. The Basic Physic Principles and Definitionsof Explosion Protection

    An explosion is the sudden chemical reaction of aflammable substance with oxygen with thesimultaneous release of high energy. Flammablesubstances may be present in the form of gases,vapours, mists or dusts. Explosion can only occur,when three factors come together (fig. 1):

    1. Flammable material (in ignitable quantities)2. Oxygen (in the air)3. Ignition source

    Certain characteristic properties of these materialsare required for safety considerations. The flashpoint of a flammable liquid is the minimumtemperature at which a liquid gives off vapour insufficient concentration to form an ignitablemixture with air near the surface of the liquid (atnormal air pressure). If the flash point of a flam-

    mable liquid is well above the maximum tempera-tures that arise, an explosive atmosphere can notbe formed. The flash point of a mixture of variousliquids may be lower than that of the individualcomponents. In addition to the boiling point, theflash point of a liquid serves to classify liquids ashighly flammable, easily flammable, and flammableliquids in the Council Directive 98/24/EC risksrelated to chemical agents.

    To form an explosive atmosphere, the flammablesubstance must be present in a certain concentra-tion (fig. 2).

    If the concentration is too high (rich mixture) or

    too low (lean mixture), no explosion occurs.Instead, there is just a steady-state combustionreaction or none at all. It is only in the rangebetween the lower and upper explosion limit thatthe mixture reacts explosively when ignited. Theexplosion limits depend on the ambient pressureand the proportion of oxygen in the air (table 2).

    Fig.1:An explosion can only occur, when these threefactors come together

    Table 1:Classification of flammable liquids

    Designation of the flammable liquid at flash point and boiling point C

    Highly flammable Flash point < 0C and boiling point < 35C

    Easily flammable Flash point < 0C and boiling point > 35Cor 0C < flash point < 21C

    Flammable 21C < flash point < 55C

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    Depending on the speed of combustion, we speakof deflagration, explosion or detonation. An atmo-sphere is described as hazardous or explosiveif there is danger to human life or property by anexplosion. An explosive atmosphere of even just afew litres can be dangerous in an enclosed space.

    Ignition sourceIgnition of an explosive atmosphere can be causedby various sources:> hot surfaces> flames and hot gases> mechanically generated sparks> electrical installations> equalizing currents, cathodic corrosion protection> static electricity> lightning> electromagnetic waves (high-frequency)> optical radiation> ionising radiation

    > ultrasonics> adiabatic compression and shock waves> exothermal reactions

    Table 2:Explosion Limits of selected Gases and Vapours

    Substance Lower explosion limit Upper explosion limitdesignation [Vol. %] [Vol. %]

    Acetylene 2,3 100 (self-decomposing!)

    Ethylene 2,4 32,6

    Gasoline ~ 0,6 ~ 8

    Benzol 1,2 8

    Heating oil/diesel ~ 0,6 ~6,5

    Methane 4,4 17

    Propane 1,7 10,8

    Carbon disulphide 0,6 60,0

    Hydrogen 4,0 77,0

    Mixture too lean

    nocombustion

    Mixture too rich

    Deflagrationno explosion

    Explosion range

    Explosionlower limit higher

    Concentration of air100 Vol % 0 Vol %

    Concentration ofcombustible substance in air0 Vol % 100 Vol %

    Fig.2:Explosion limits

    Extract from the table Sicherheitstechnische Kenngren, Band 1: BrennbareFlssigkeiten und Gase (Safety characteristics, vol.1: flammable liquids and gases) bE. Brandes and W. Mller as well as by T. Redeker and G. Schn (6 th addendum)

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    2. the basic physic principles and definit

    Mitigation of the explosion effects(Constructive Explosion Protection)If hazardous explosive atmospheres cannot besafely avoided and their ignition cannot be excluded,then measures must be taken which limit the effectof explosions to a safe degree, e.g.by means of:> explosion pressure resistant construction> explosion relief devices> explosion suppression by means of

    extinguishers

    The principle of integrated explosion protectionrequires following explosion protection measuresin a certain sequence.

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    23

    Preventing theformation of an explosiveatmosphere

    Avoidance of the

    ignition of an explosiveatmosphere

    Mitigation of the effectsof an explosion toan acceptable extent

    Integrated explo-sion protection

    Preventing explosive atmospheres(Primary Explosion Protection)The term primary explosion protection refers to allprecautions, which prevent a hazardous explosiveatmosphere from being created. This can beachieved by:> avoiding flammable substances

    (replacement technologies)> inerting (addition of nitrogen,

    carbon dioxide etc.)> limitation of the concentration by means of

    natural or technical ventilation

    Avoiding ignition of explosive atmospheresIf the danger of explosion cannot be completelyor only partly avoided by measures of preventingthe formation of an hazardous explosive atmo-sphere, then measures must be taken thatavoid the ignition of the explosive atmosphere.

    The required safety level of these measuresdepends on the possible danger potential in theinstallation location. The hazardous areasare therefore divided into zones, according tothe probability of an explosive atmosphere beingformed (see Section 3.2.2).

    In the USA and other countries, hazardouslocations are classified into Classes and Divisions(see Section 6.2). For locations classified inthis way, requirements must be met concerningthe apparatus, which are approved for use in theselocations. In addition, it is also necessary toprove that these requirements have been met.

    Fig. 3:Basic principles of explosion protection

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    3. statutory regulations and standards

    3. Statutory Regulations

    3.1 Introduction

    Areas in which there is a risk of explosion thatmay harm people or the environment are subjectto legal or comparable rules in most countriesof the world. While these rules were initiallyissued at the national level, they have since beenreplaced over the last years by regional EuropeanDirectives and Standards, and in the field ofstandardization they have partially been replacedby international regulations.

    3.2 European Directives

    Already in 1976, the Council of the EuropeanCommunity established the prerequisite offree trade of explosion protected electrical equip-

    ment within the European Union by ratifyingthe Directive on the harmonization of the lawsof the member states concerning electricalequipment for use in potentially explosive atmo-spheres (76/117/EEC). This directive has sincebeen adapted to the state of the art by means ofexecution and adaptation directives onelectrical equipment.

    Complete harmonization and extension to all typesof equipment was achieved with the newDirective 94/9/EC in 1994. The Directive 99/92/EC,which regulates operation in hazardous areasand defines safety measures for the concernedpersonnel, was issued in 1999.

    3.2.1 The Directive 94/9/EC (ATEX 95)

    The EC Directive 94/9/EC on the approximation ofthe laws of the Member States concerning equip-

    ment and protective systems intended for usein potentially explosive atmospheres was issuedin 1994 to further standardize explosion protectionand make corresponding adjustments in line witha new directive approach. It specifies the require-ments for explosion protected equipment andprotective systems by prescribing essential healthand safety requirements. It guarantees freetrade within the European Community, as agreedin Article 95 (former 100a) of the Treatyestablished between the European Communitymember states. This is also where the termgenerally used amongst experts, ATEX 95 or 100a,comes from. This term is the abbreviation ofthe French designation for explosive atmosphereatmosphres explosibles.

    The directive had to be implemented into nationallaw without any changes/exceptions. E.g. itwas adopted into british law by means of The

    Equipment and Protective Systems for Usein Potentially Explosive Atmospheres Regulations(EPS) and into German law by means of theExplosionsschutzverordnung (ExVO) (Regulationof Explosion Protection) as the 11th Regulation ofthe Gerte- und Produktsicherkeitsgesetz (GPSG)(Equipment and Product Safety Law).

    The directive applies to all industrial potentiallyexplosive areas including mining, and also coversdust explosion protection. The scope coversall electrical and non-electrical equipment, andprotective systems.

    This directive is intended for the manufactureror the importer, and defines design, certification,production and quality assurance, marking,operating instructions, and declaration of conform-ity for the explosion protected equipment to beplaced on the market.

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    3. statutory regulations and standards0

    or dusts in which, after ignition has occurred,combustion spreads to the entire unburnedmixture.

    > A potentially explosive atmosphere is anatmosphere which could become explosive dueto local and operational conditions.

    ScopeThe directive applies to equipment and pro-tective systems for use in potentially explosiveatmospheres.

    Safety devices intended for use outside potentiallyexplosive atmospheres but required for or con-tributing to the safe functioning of equipment withrespect to the risk of explosion are also coveredby the scope of this Directive. The Directive doesnot include a reference to mandatory standards,whereas it specifies the essential health andsafety requirements to be maintained, and which

    are mandatory for design and construction.Protection against other hazards (e.g. electricshock) that could be caused by this equipment,is also required as well.

    Equipment categoriesThe manufacturer of equipment that includes theirown potential ignition sources, and thereforecan cause an explosion, have to ensure that theequipment undergoes an ignition hazard assess-ment procedure, and takes measures according tothe essential safety requirements to exclude therisk of ignition. In the directive, Group II apparatusare divided into three categories with variouslevels of safety (for mines Group I has two cate-gories). The required protective measures suit therequired level of safety (tables 3 and 4).

    Definitions> Equipment means machines, apparatus,

    fixed or mobile devices, control components andinstrumentation thereof, and detection orprevention systems which, separately or jointly,are intended for the generation, transfer,storage, measurement, control, and conversionof energy for the processing of material andwhich are capable of causing an explosionthrough their own potential sources of ignition.

    > Protective systems is the definition for designunits, which are intended to halt incipientexplosions immediately and/or to limit theeffective range of explosion flames andexplosion pressures. Protective systems may beintegrated into equipment separately and placedon the market for use as autonomous systems.

    > Components means any item essential to thesafe functioning of equipment and protectivesystems but with no autonomous function.

    > An explosive atmosphere is a mixture with air,under atmospheric condition, of flammablesubstances in the form of gases, vapours, mists,

    Table 3:Categories of Group I: Surface and Underground Mining Systems in case ofDangerous Firedamp/Dust

    Category M1 Category M2

    Very high degree of safety High degree of safety

    Safe even when two faults Switch-off in case of the presence ofoccur independently explosive atmosphere

    Table 4:Categories of Group II: Other Explosive Areas

    Category 1 Category 2 Category 3

    Very high degree of safety High degree of safety Normal degree of safety

    Safe even when two faults Safe even when a Safe during normaloccur independently fault occurs operation

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    CertificationEquipment for use in hazardous areas has toundergo the conformity assessment proceduredefined in the directive prior to being placed onthe market. Category 1 and M1 equipment mustundergo an EC type examination carried out by aNotified Body. The same applies to electricalequipment and I.C.-engines of Category 2 and M2.For non-electrical equipment of this category,as well as for those of Category 3, the manufac-turer is authorized to assess and documentconformity with the requirements of the directive.

    The certificates from a Notified Body are recog-nized throughout the European Community.

    MarkingIn addition to the usual data such as the nameof the manufacturer, type, serial number, andelectrical ratings, any data relating to explosion

    protection must be contained in the marking(see table 5, marking according to the 94/9/ECDirective and the standards EN 60079 ff and EN61241 ff).

    The CE marking of the equipment confirms that itis designed and manufactured in compliance withall applicable EC Directives. For example, anexplosion protected luminaire marked with the CEconformity mark must comply with both theATEX Directive as well as the EMC Directive.

    Operating instructionsThe operating instructions of the manufacturermust clearly define the intended use of theequipment by the operator. The minimumrequirements for the operating instruction areamongst others:Information on safe> putting into service> use> assembling and dismantling> maintenance (servicing and emergency repair)> installation> adjustment

    If necessary, special conditions for safe use haveto be specified and should include notes onpossible misuse that may occur as experience hasshown.

    Manufacturers Declaration of Conformity

    Equipment and systems can be placed on themarket, only if marked with the CE mark and com-plete with operating instructions and the manufac-turers declaration of conformity. The CE conformitymarking and the written declaration of conformityconfirm that the product complies with all require-ments and assessment procedures specified inthe EC Directives.

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    3. statutory regulations and standards2

    Table 5:Marking of electrical equipment

    Marking defined by directives and standards

    Manufacturers name or designation

    Type designation (e.g.) 6000/562

    Address D-74638 Waldenburg

    Explosion protection marking EEx de IIC T6

    Marking according to CENELEC EEx oder Ex (starting from 12/2004)Types of protection d, e, ib, [ib], 1

    Explosion groups for gases IIA, IIB oder IIC

    Temperature class or in case of dust the T1T6max. surface temperature of apparatus

    Marking according to Directive 94/9/EC II 2 G D

    EU distinguishing mark

    Equipment group I, II

    Equipment category 1, 2 oder 3

    G: Gases, vapours or mists; D: dusts G, D

    Testing authority, number of certificate PTB 97 ATEX 20312

    CE mark, number of the auditing and supervising authority 0102

    Electrical ratings V, A, W, Hz

    Ambient temperature, Ta

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    Assessment of explosion risksWhen assessing the risks of explosion, thefollowing factors are to be taken into account:> the likelihood that explosive atmospheres

    will occur and their persistence> the likelihood that ignition sources, including

    electrostatic discharges, will bepresent and become active and effective

    > the installations, substances used, processes,and their possible interactions

    > the scale of the anticipated effects

    Zone ClassificationThe employer has to classify the areas in whichexplosive atmospheres may be present into zones,and to ensure that the minimum organisationaland technical requirements of the Directive areobserved.

    Zone 0

    A place in which an explosive atmosphere con-sisting of a mixture with air of flammablesubstances in the form of gas, vapour or mist ispresent continuously or for long periods orfrequently.

    Zone 1A place in which an explosive atmosphere con-sisting of a mixture with air or flammablesubstances in the form of gas, vapour or mist islikely to occur in normal operation occasionally.

    Zone 2A place in which an explosive atmosphere con-sisting of a mixture with air of flammablesubstances in the form of gas, vapour or mist isnot likely to occur in normal operation but, ifit does occur, will persist for a short period only.

    3.2.2 The Directive 99/92/EC

    In addition to the 94/9/EC Directive, whichregulates how explosion protected equipment andprotective systems are placed on the marketand the design, construction and quality require-ments to be met by them, the 99/92/EC Directivestating Minimum requirements for improving thehealth and safety protection of worker potentiallyat risk from explosive atmospheres refers tothe operation of potentially explosive installations,and is therefore intended for the employer. Thisdirective contains only minimum requirements.When implementing it into national law, the singlestates can adopt further regulations. This wasdone when implementing it into British law byThe Dangerous Substances and Explosive Atmo-spheres Regulations (DSEAR) and into Germanlaw by the Betriebssicherheitsverordnung(BetrSichV), the German regulation on Industrial

    Safety and Health Protection, which in additionto this directive, takes into consideration furtherEuropean directives on safety on work.Comparable regulations are found in otherEuropean countries.

    According to the 99/92/EC Directive, it is theduty of the employer to verify where there is arisk of explosion, classify the hazardous areas intozones accordingly, and document all measurestaken to protect the personnel in the explosionprotection document.

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    3. statutory regulations and standards4

    Zone 20A place in which an explosive atmosphere inthe form of a cloud of combustable dust in air ispresent continously, or for long periods orfrequently.

    Zone 21A place in which an explosive atmosphere in theform of a cloud of combustible dust in air islikely to occur in normal operation occasionally.

    Zone 22A place in which an explosive atmosphere in theform of a cloud of combustible dust in air isnot likely to occur in normal operation but, if itdoes occur, will persist for a short period only.

    Table 6 contains an overview of the zones andallocation of equipment according to the category.

    Explosion protection documentAn explosion protection document has to begenerated, which contains at least the followinginformation:> assessment of the explosion risk> protective measures taken> zone classification> observance of minimum requirements. These

    are divided into organisational measures(instruction of workers, etc.) and technicalmeasures (explosion protection measures).

    3.3 Standards

    The European Standards EN 50014 - EN 50020 onelectrical equipment were issued in 1978 andreplaced the national standards for this equipmentvalid up until then Europe-wide. In addition tothe standards for electrical equipment publishedby the CENELEC, standards for non-electrical

    explosion-protected equipment have since beendeveloped by the CEN.

    According to an agreement between the EuropeanCommittee for Electrotechnical StandardizationCENELEC and the International ElectrotechnicalCommission IEC, the European standards forelectrical equipment have been adopted unchangedby the IEC for several years. The EuropeanStandard series EN 50014, which defines the re-quirements on equipment to be used in explosivegas atmospheres, will be gradually replaced bythe European Standards series EN 60079.These standards have been issued as VDE 0170in Germany.

    Table 6:Zones and allocation of equipment according to the category

    Zone Duration of the occurrence Equipmentof an explosive atmosphere category

    Gases, 0 continuously, for a long period, 1Gvapours, frequentlymists

    1 occasionally 2G

    2 rarely and for a short period 3G

    Dusts 20 continuously, for a long period, 1Dfrequently

    21 occasionally 2D

    22 rarely and for a short period 3D

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    Table 7:Electrical Apparatus for Explosive Gas Atmospheres

    EN (old) EN (new) IEC

    General requirements EN 50 014 EN 60079-0 IEC 60079-0

    Flameproof enclosures d EN 50 018 EN 60079-1 IEC 60079-1

    Pressurized enclosures p EN 50 016 EN 60079-2 IEC 60079-2

    Powder filling q EN 50 017 EN 60079-5 IEC 60079-5

    Oil immersion o EN 50 015 EN 60079-6 IEC 60079-6

    Increased safety e" EN 50 019 EN 60079-7 IEC 60079-7

    Intrinsic safety i EN 50 020 EN 60079-11 IEC 60079-11

    Type of protection n EN 50 021 EN 60079-15 IEC 60079-15

    Encapsulation m EN 50 028 EN 60079-18 IEC 60079-18

    Intrinsically safe systems EN 60079-25 IEC 60079-25

    Electrical equipment for Zone 0 EN 50 284 EN 60079-26 IEC 60079-26

    Intrinsically safe field bus systems EN 60079-27 IEC 60079-27

    Optical radiation op EN 60079-28 IEC 60079-28

    Table 8:Electrical Apparatus for Use in the Presence of Combustible DustEN (old) EN (new) IEC (new) IEC (old)

    General requirements EN 61241-0 IEC 61241-0 IEC 61241-1-1

    Protected by enclosures tD EN 50281-1-1 EN 61241-1 IEC 61241-1 IEC 61241-1-1

    Pressurized enclosures pD EN 61241-2 EN 61241-2 EN 61241-4

    Intrinsic safety iD EN 61241-11 IEC 61241-11 EN 61241-5

    Encapsulation mD EN 61241-18 IEC 61241-18

    The requirements on types of protection for areaswhere combustible dust may occur are specifiedin the standard series IEC 61241. In Europe, thesestandards replace the existing series EN 50281.

    Since many requirements are identical to the stan-dards for explosive gas atmospheres, both stan-dard series will be summarized in the series IEC orEN 60079 (tables 7 and 8).

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    4. technical principles6

    4. Technical Principles

    4.1 Zone Classification

    Hazardous areas are classified into zones to facili-tate the selection of appropriate electrical appa-ratus as well as the design of suitable electricalinstallations. Information and specificationsfor the classification into zones are included in IEC60079-10.

    The greatest potential risk has to be taken intoaccount when classifying the potentially explosiveareas into zones and determining the necessaryprotective measures.

    If there is no expert (skilled person) available inthe company to verify the risk of explosion and todetermine the necessary measures, it is recom-mended that a competent authority be turned to.

    The equipment used in the defined hazardouszone must meet the requirements of the relevantassigned category (see section 3.2.1).

    4.2 Minimum Ignition Energy andExplosion Group

    The minimum ignition energy is the minimumenergy just sufficient to ignite the most ignitablemixture. This characteristic has to be consideredwhen selecting the apparatus. The measuredvalue of the minimum ignition energy is indicatedfor dusts. Gases are divided into explosion groups.

    Explosion groupsApparatus are divided into two groups:> Group I:

    Electrical apparatus for mines endangeredby firedamp

    > Group II:Electrical apparatus for other places liableto be endangered by explosive atmospheres

    In the case of electrical apparatus in Group I

    (mining), it is assumed that the only flammablegas that can occur is methane, but combinedwith coal dust. Other flammable gases, which canalso occur in these areas, must be furtherclassified as shown in Group II.

    Electrical apparatus of Group II used in explosivegas atmospheres are further classified intoexplosion groups.

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    Table 9:Explosion Groups

    Explosion group Maximum experimental safe gap Minimum ignition current ratio*

    IIA > 0,9 > 0,8

    IIB 0,5 0,9 0,45 0,8

    IIC < 0,5 < 0,45

    Classification criteria are the MaximumExperimental Safe Gap (MESG) and the MinimumIgnition Current (MIC). The MESG and MICare determined for the various gases and vapouraccording to a stipulated testing arrangement.The maximum experimental safe gap is the gap ofthe test apparatus with a width of flameproofjoint of 25 mm at which an internal ignition of anexplosive mixture is not propagated to the exterior(IEC 60079-1-1). The minimum ignition currentrelates to the minimum ignition current for labora-tory methane.

    An overview of the maximum experimental safegaps and minimum ignition currents for the variousexplosion groups is shown in table 9.

    The dangerousness of the gases increases fromexplosion group IIA to IIC. The requirements forthe electrical apparatus increase accordingly to

    these explosion groups. For this reason, the mark-ing of the electrical apparatus must show towhich explosion group it belongs. Electricalapparatus approved for IIC may also be used forall other explosion groups.

    *rel. to methane = 1

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    4. technical principles8

    4.3 Ignition Temperature andTemperature classes

    The ignition temperature of a flammable gas,vapour, or combustible dust is the lowest temper-ature of a heated surface at which the gas/air orvapour/air mixture ignites. It represents virtuallythe lowest temperature at which a hot surface canignite a respective explosive atmosphere.

    Flammable gases and vapours are classified intotemperature classes according to their inflamma-bility. The maximum surface temperature of elec-trical apparatus should always be lower than theignition temperature of the gas/air or vapour/airmixture in which it is used. Of course, equipmentclassified in a higher temperature class (e.g. T5)may also be used for applications in which a lowertemperature class is required (e.g. T2 or T3).In North America there is a system incorporating

    further classification according to temperaturesubclasses.

    Combustible dusts are not divided into tempera-ture classes. The minimum ignition temperature ofthe dust cloud has to be compared with the max.surface temperature of the apparatus. In doing so,a safety factor has to be considered. The max.surface temperature of the apparatus must notexceed 2/3 of the minimum ignition temperature ofthe dust cloud. Since dust can also deposit onapparatus, the minimum ignition temperature ofthe dust layer must also be taken into account.This temperature is the lowest temperature of ahot surface on which a dust layer of 5 mm canbe ignited. The max. surface temperature of theapparatus has to be adjusted using a safetyfactor of 75 K. The thicker the layer, the higher theheat insulation. For this reason, the dust layeris already ignitable at low temperatures, which iswhy a reduced surface temperature is admittedon the apparatus. It is determined according to thescheme (fig. 4) (EN 61241-14). If the layer is

    thicker than 50 mm, the ignition temperature hasto be determined by laboratory tests. This appliesalso to layers thicker than 5 mm when the ignitiontemperature at 5 mm is lower than 250 C. Labo-ratory testing is also necessary when the appara-tus are completely covered with combustible dust.

    Ignition temperature of a5 mm thick layer

    Thickness of layer [mm]

    M a x . p e r m

    i s s i

    b l e s u r f a c e t e m p e r a t u r e

    [ C ]

    100

    20 0

    300

    10 20 30 40 50

    400 C 320 C

    250 C

    Fig. 4:Determination of the max. Surface Temperature of Dust Layers of 5 mm to 50 mm

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    4.4 Types of Protection

    Only explosion protected equipment may be usedin areas in which an explosive atmosphere maystill be expected despite the implementation ofprevention measures. Electrical, explosion protect-ed equipment can have various types of protectionaccording to the construction regulations of thestandards series EN 60079, former EN 50014 andfollowing. If electrical equipment shall be usedin areas with combustible dust, the standardsseries EN 61241 is applicable. The type of protec-tion employed by the manufacturer dependsmainly on the kind and function of the apparatus.Various safety levels exist for some types ofprotection. These correspond to the equipmentcategories as defined in the 94/9/EC Directive.The Ex ia version relative to intrinsic safety canbe classified as category 1. It can be installedin Zone 0. The Ex ib version corresponds to

    category 2 which suits Zone 1. From a safetypoint of view, all standardized types of protectionshould be seen as being equal.

    The tables 1013 give an overview of the stan-dardized types of protection, and describes thebasic principle, as well as the usual applications.

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    4. technical principles0

    Table 10:Types of Protection for Electrical Apparatus in Explosive Gas Atmosphere, Part 1

    Basic principle

    Additional measures are applied to increase the levelof safety, thus preventing the possibility of excessive temperatures and the occurance of sparks or electricarcs within the enclosure or on exposed parts ofelectrical apparatus, where such ignition sourceswould not occur in normal service.

    Parts which can ignite a potentially explosive atmo-sphere are surrounded by an enclosure which with-stands the pressure of an explosive mixture explodinginside the enclosure, and prevents the transmissionof the explosion to the atmosphere surrounding the enclosure.

    The formation of a potentially explosive atmosphereinside a casing is prevented by maintaining apositive internal pressure of protective gas in relation to the surrounding atmosphere and, where necessary,by supplying the inside of the casing with a constantflow of protective gas acting to dilute any com-bustible mixtures.

    Apparatus used in a potentially explosive area con- tain intrinsically safe electric circuits only. An electriccircuit is intrinsically safe if no sparks or thermaleffects produced under specified test conditions(which include normal operation and specific faultconditions) is not capable of causing ignition of agiven explosive atmosphere.

    Intrinsic Safety evaluation for defined systems(equipment and cables)

    Definition of the physical and electrical limit values of the intrinsically safe bus string

    Main application

    Terminal and connection boxes, controlboxes for installing Ex-components (whichhave a different type of protection), squirrel-cage motors, light fittings

    Switchgear and control gear and displayunits, control systems, motors, transformers,heating equipment, light fittings

    Switchgear and control cabinets, analysers,large motors

    px = use in Zone 1, 2py = use in Zone 1, 2pz = use in Zone 2

    Measurement and control technology, com-munication technology, sensors, actuators

    ia = use in Zone 0, 1, 2ib = use in Zone 1, 2[Ex ib] = associated apparatus installation in safe area

    Intrinsically safe systems

    Fieldbus intrinsically safe concept (FISCO)for Zone 1

    Fieldbus Nonincendive Concept (FNICO)for Zone 2

    Type of protection inaccordance with IEC, EN,UL, FM and NFPA

    Increased safety eEN 60079-7 UL 60079-7IEC 60079-7 FM 3600

    Flameproof enclosure dEN 60079-1 UL 60079-1IEC 60079-1 FM 3600

    Pressurized enclosure pEN 60079-2 NFPA 496IEC 60079-2 FM 3620

    Intrinsic Safety iEN 60079-11 UL 60079-11IEC 60079-11 FM 3610

    EN 60079-25IEC 60079-25

    EN 60079-27

    IEC 60079-27

    Representation(diagram)

    FISCO Ex ia IIC T4

    FNICO Ex ia IIC T4

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    Table 11:Types of Protection for Electrical Apparatus in Explosive Gas Atmosphere, Part 2

    Basic principle

    Electrical apparatus or parts of electrical apparatusare immersed in a protective fluid (such as oil),such that a potentially explosive atmosphere existingover the surface or outside of the apparatus cannotbe ignited.

    Filling the casing of an electrical apparatus with afine granular packing material has the effect ofmaking it impossible for an electric arc created in thecasing under certain operating conditions to ignite apotentially explosive atmosphere surrounding thecasing. Ignition must not result either from flames orfrom raised temperature on the surface of the casing.

    Parts that are capable of igniting an explosive atmo-sphere by either sparking or heating are enclosedin a compound in such a way as to avoid ignition ofan explosive atmosphere.

    Electrical apparatus cannot ignite a explosiveatmosphere surrounding them (in normal operationand under defined abnormal operating conditions).

    Appropriate measures prevent ignition of an explosiveatmosphere by optical radiation.

    Main application

    Transformers, starting resistors

    Sensors, display units, electronic ballast, transmitter

    Switchgear with small breaking capacity,control and signalling units, display units,sensors

    ma = use in Zone 0, 1, 2mb = use in Zone 1, 2

    All electrical equipment for Zone 2

    nA = non-sparking apparatusnC = sparking apparatus in which contactsare protected convenientlynL = energy-limited apparatusnR = purged/pressurized apparatusnZ = purged pressurized apparatus, n

    Optical fibre

    There are three different methods:

    Ex op is = intrinsically safe optical radiationEx op pr = protected optical radiationEx op sh = blocking optical radiation

    Type of protection inaccordance with IEC, EN,UL, FM und NFPA

    Oil immersion oEN 60079-6 UL 60079-6IEC 60079-6 FM 3600

    Powder filling qEN 60079-5 UL 60079-5IEC 60079-5 FM 3600

    Encapsulation mEN 60079-18 UL 60079-18IEC 60079-18 FM 3600

    Type of protection n_EN 60079-15 UL 60079-15IEC 60079-15 FM 3600

    Optical radiation op_EN 60079-28IEC 60079-28

    Representation(diagram)

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    4. technical principles2

    Table 12:Electrical Apparatus for Use in the Presence of Combustible Dust

    Basic principle

    Thanks to the tightness, dust cannot ingress the appa-ratusat all or its quantity is limited to a safe degree.For this reason, ignitable apparatus can be mounted into the enclosure. The surface temperature of the enclosuremust not ignite the surrounding atmosphere.

    The formation of a potentially explosive atmosphereinside a casing is prevented by maintaining a positiveinternal pressure of protective gas in relation to thesurrounding atmosphere and, where necessary, by sup-plying the inside of the casing with a constant flowof protective gas which acts to dilute any combustiblemixtures.

    Apparatus used in a potentially explosive area containintrinsically safe electric circuits only. An electric circuitis intrinsically safe if no sparks or thermal effectsproduced under specified test conditions (which includenormal operation and specific fault conditions) is notcapable of causing ignition of a given explosive atmo-sphere.

    Parts that are capable of igniting an explosive atmo-sphere by either sparking or heating are enclosedin a compound in such a way as to avoid ignition ofa dust layer or cloud.

    Main application

    Switchgear and control gear, control,connection, and terminal boxes, motors,light fittings

    td A21 = according to method A for Zone 21 td B21 = according to method B for Zone 21

    Switchgear and control cabinets, motors

    Measurement and control technology, com-munication technology, sensors, actuators

    iaD = use in Zone 20, 21, 22ibD = use in Zone 21, 22[Ex ibD] = associated electrical apparatus installation in safe area

    Switchgear with small capacity, control andsignalling units, display units, sensors

    maD = use in Zone 20, 21, 22mbD = use in Zone 21, 22

    Type of protection inaccordance with IEC or EN

    Protectedby enclosures tDEN 61241-1IEC 61241-1

    Pressurized enclosure pDEN 61241-4IEC 61241-4

    Intrinsic Safety iDEN 61241-11IEC 61241-11

    Encapsulation mDEN 61241-18IEC 61241-18

    Repre-sentation(diagram)

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    Table 13:Types of Protection for Non-electrical Apparatus in Explosive Gas Atmosphere and used in the Presence of Combustible Dust

    Basic principle

    Proven technical principles are applied to equipment types which do not have any ignition source undernormal operating conditions, so that the risk ofmechanical failure which cause ignitable temperaturesand sparks is reduced to a minimum degree.

    Parts which can ignite a potentially explosive atmo-sphere are surrounded by an enclosure which with-stands the pressure of an explosive mixture explodinginside the enclosure, and prevents the transmissionof the explosion to the atmosphere surrounding theenclosure.

    The formation of a potentially explosive atmosphere in-side a casing is prevented by maintaining a positiveinternal pressure of protective gas in relation to thesurrounding atmosphere and, where necessary, by sup-plying the inside of the casing with a constant flow ofprotective gas acting to dilute any combustible mixtures.

    Sensors are integrated in the equipment to detecthazardous conditions to come, and to take steps against them before potential ignition sources become effective.The measures can be initiated automatically by meansof a direct connection between the sensors and the ignition protection system or manually by issuinga warning message intended for the operator of theequipment.

    Ignition sources are rendered inactive by immersionin a protective liquid or by constant moistening using aliquid film.

    The effective sealing of the enclosure can reducepenetration of explosive atmosphere to an extent that nopotentially explosive atmosphere can form in it. Pressuredifferences between the interior and the exterior atmo-sphere have to be taken into account. Application islimited to equipment category 3.

    Main application

    Couplings, pumps, gearing, chain drives,belt conveyors

    Brakes, couplings

    Pumps

    Pumps, belt conveyors

    Submerged pumps, gears,liquid immersion

    Equipment exclusively for Zone 2 or Zone 22

    Type of protection inaccordance with IEC or EN

    Constructional safety cEN 13463-5

    Flameproof enclosure dEN 13463-3

    Pressurized enclosure pEN 13463-7

    Ignitionsource monitoring bEN 13463-6

    Liquid immersion kEN 13463-8

    Restricted breathing frEN 13463-2

    Repre-sentation(diagram)

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    4. technical principles4

    Fig. 5:Combination of Types of Protection Emergency Light Fitting C-Lux 6108

    4.4.1 Application and Combination ofTypes of Protection d and e

    The most important type of protection for switch-gear is Flameproof Enclosures, usually inconjunction with Increased Safety. Switchgeardoes produce sources of ignition in normal use andtherefore Increased Safety alone is not appli-cable as type of protection for switchgear, since

    Ex de

    Ex mEx de

    Ex deEx d

    Ex e Ex e

    Ex e

    Increased Safety is based on the principle toavoid sources of ignition by additional measures.However, Increased Safety, in conjunction withFlameproof Enclosures, cut a fine figure forswitchgear and control gear. Modern, explosionprotected luminaires also use a combinationof several types of protection to achieve the bestresults with regard to safety, function, andeconomy (fig. 5).

    Ex emEx e

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    4.4.2 Applications of Type of ProtectionIntrinsic Safety

    The type of protection Intrinsic Safety is basedon the principle of energy limitation within anelectric circuit. The energy from a power circuitcapable of causing an explosive atmosphere toignite is thus limited to such an extent that thesurrounding explosive atmosphere cannot igniteas a result of sparks or inadmissible surface heat-ing of the electrical components.

    The type of protection Intrinsic Safety is partic-ularly used in measurement and control tech-nology, as no high currents, voltage and powerare required here.

    Terms and Definitions

    Intrinsically safe electrical circuit

    An electric circuit in which neither a spark northe effect of heat can cause a defined explosiveatmosphere to ignite.

    Intrinsically safe apparatusElectrical apparatus in which all circuits areintrinsically safe.

    Associated apparatusElectrical apparatus which contains circuits, someof which are intrinsically safe and some are not,and which is constructed such that the non-intrin-sically safe circuits cannot negatively adverselyaffect the intrinsically safe circuits (table 14).

    Minimum ignition energyThe minimum ignition energy of a gas/air andvapour/air mixture is the smallest level of electri-cal energy which occurs while a capacitor isdischarging, and which may still be sufficient toignite the most ignitable mixture of a gas orvapour and air at atmospheric pressure and 20 C.

    An essential aspect of the type of protectionIntrinsic Safety is reliability with regard to theobservance of voltage and current limit values,even if determined faults may occur. Intrinsicallysafe apparatus and intrinsically safe components

    from related equipment are classified in differentlevels of protection ia, ib or ic with regardto infallibility. The level of protection ia is aprerequisite for category 1 equipment and suitablefor use in Zone 0, the level of protection ibfor category 2 equipment and suitable for use inZone 1. The new level of protection ic for cate-gory 3 is suitable for use in Zone 2.

    Table 14:Difference between Intrinsically Safe and Associated Apparatus

    Intrinsically safe apparatus Associated apparatus

    These contain intrinsically safe circuits only These contain both intrinsically safe and non-intrinsically safe electric circuits

    EEx ib IIC T6 [EEx ib] IIC T6 EEx de [ib] IIC T6

    All necessary information such as category, ex- The square brackets indicate that the associated electrical apparatus contains an intrinsicaplosion group and temperature class is provided. safe electric circuit that may be introduced into Zone 1, gas groups IIA, IIB and IIC.

    The apparatus may be used in Zone 1. The apparatus has to be installed outside Thanks to being integrated in a flameproof the potentially explosive area. enclosure (d), the apparatus may be used

    in Zone 1.

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    Level of protection ia

    Electrical apparatus of level of protection iashall not be capable of causing ignition in

    normal operation and when one fault occurs orwhen a combination of any two faults occurs.

    Safety factor 1.5:During normal operation and in case of onefault

    Safety factor 1.0:Two independent faults

    Level of protection ib

    Electrical apparatus of level of protection ibshall not be capable of causing ignition in

    normal operation or when one fault occurs.

    Safety factor 1.5:During normal operation and in case of onefault

    Safety factor 1.0:In case of one fault, if the electrical apparatusdoes not have unprotected switching contactsin those components, which may be exposed to an explosive atmosphere, and when the faultis monitored.

    Table 15:Levels of protection of intrinsically safe electrical circuits

    4. technical principles6

    Fig.6:Electric Isolators IS pac

    Isolation of Intrinsically Safe Circuits fromNon-intrinsically Safe CircuitsAn important measure for intrinsically safe circuitsis the safe isolation of all intrinsically safecircuits from non intrinsically safe circuits (fig. 6).Safe electrical isolation is always required, withthe exception of safety barriers.

    Electric isolation is generally recommanded forZone 0. Zener diodes, used for limiting voltage,as well as other semiconductor components areconsidered to be fallible and must therefore besafeguarded by means of redundant components.Wire wound or sheet resistors for current limi-tation are considered to be infallible components(they have high resistivity in the event of a fault).Therefore one single component is sufficient.

    Normal safetySafety is required under normal operation.

    The failure of the zener diode is not taken intoaccount. (level of protection ic: one singlezener diode).

    Level of protection ic

    Electrical apparatus of level of protection icshall not be capable of causing ignition in

    normal operation.

    Safety factor 1.0:During normal operation

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    Single fault safetyIn the event of the failure of one zener diode,a second zener diode must take its function(level of protection ib: one redundant zenerdiode).

    Double fault safetyIn the event of a failure of two zener diodes,a third zener diode must take their function(level of protection ia: two redundant zenerdiodes, table 15).

    4.4.3 Applications of Type of Protection c

    Non-electrical apparatus are often realised with thetype of protection Constructional safety. The riskof failure, which may cause ignition sources inan apparatus, is reduced to a low level by meansof constructional measures for this type of protec-tion. To do so, e.g., hot surfaces, mechanically

    generated sparks, and electrostatic discharges areexamined. The measures depend mainly on theequipment type and may vary significantly. Here,the examined material combination, dimensioning,tolerances, and lubricants of moving parts playa role. Even servicing intervals and monitoring ofthe service life may be of vital importance.The manufacturer defines the intended use in theoperating instructions. By doing so, ambient andoperating conditions as well as the admittedoperating parameters are specified. The operatorhas to observe the operating instructions.

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    5. Installation and Operation of ElectricalEquipment in Hazardous Areas

    5.1 Duties of Installer, Manufacturerand Employer

    Safety in potentially explosive areas can only beguaranteed by a close and effective workingrelationship amongst all parties involved (fig. 7).The employer is responsible for the safety of hisinstallations. It is his duty to verify where thereis a risk of explosion and then divide areas intoZones accordingly. He must ensure that the instal-lation is installed in accordance with regulationsand is inspected before initial use. The installationmust be kept in a regular and correct state byperiodic inspection and maintenance.

    The installer must observe the installationrequirements, and select and install the electric

    apparatus correctly for its intended use.

    Manufacturers of explosion protected apparatusare responsible for routine testing, certificationand documentation and are required to ensure thateach device manufactured complies with theapproved design.

    5.2 Classification of Zones and Selectionof Apparatus

    The question of possible risks of explosion mustbe addressed at the early stages new facilityplanning. When classifying potentially explosiveareas, the influence of natural or technicalventilation must be considered in addition to thequantity of flammable substances being released.Furthermore, the explosion safety characteristicsmust be ascertained for the flammable

    5. installation and operation of electrical8

    Installer

    Employer Testing author ity

    Author ity

    S tandardizationManufac turer

    Fig. 7:: Co-operation of all parties involved

    substances being used (see Appendix 7.2). Onlythen can a decision be reached on the classifi-cation of potentially explosive areas into Zonesand the selection of suitable apparatus.IEC 60 079-14 (EN 60079-14) applies to the instal-lation of electrical apparatus in explosive gasatmospheres Group II. IEC 61241-14 (EN 61241-14)

    applies to all areas with combustible dust.

    Equipment shall only be used within the ambienttemperature range stipulated in its marking.

    If the marking does not contain any information,the standard range of between 20 C and +40 Cdoes apply.

    Electrical apparatus with the types of protectiond and i must correspond to an explosion groupIIA, IIB or IIC. Electrical apparatus must be selectedand installed such that it is protected againstexternal influences which may adversely affect theexplosion protection measures.

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    5.3 Methods of Installation

    Essentially, three systems are used for electricalinstallations in hazardous areas:> 1. Cable system with indirect entry> 2. Cable system with direct entry> 3. Conduit systemThe technical design of the electrical apparatusused with the individual types of installationis accordingly different.

    Only the conduit system or mineral insulatedcables (MI) are permitted in the USA for all appli-cations in Class 1, Division 1 in accordance withNEC 501-4, whereby the mineral insulated cablesare mainly used as heating lines and fire resistantsignal and control lines. Certain types of cableand line are also permitted in Division 2. A com-parison of the various systems is shown below.

    Cable systemsCable systems are mainly used in Europe. For this,high-quality cables are laid uncovered. It is onlyin areas in which mechanical damage couldbe expected that they are laid in conduits that areopen at both ends.

    In the case of indirect entry, the cables and linesare conducted via cable glands into a connectionchamber in the type of protection IncreasedSafety and connected to the terminals also pro-vided in Increased Safety. From here, theindividual wires are conducted via flameproofbushings into the flameproof enclosure.

    The cable bushings are installed by the manufac-turer, with the result that, by contrast withdirect entry, a routine test of the factory wiredflameproof enclosure can be made.

    The installation engineer need only open theconnection chamber for the connection, not theflameproof enclosure.

    In the case of direct entry, the connectingcables are entered directly into the flameproofenclosure. Only cable glands that have beenspecially certified for this purpose may be usedfor this type of entry.

    Fig. 8:Methods of Installation worldwide:Left: Cable system with indirect entry; Centre: Cable system with direct entry;Right: Conduit system

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    5. installation and operation of electrical0

    The flexible gasket and the cable sheath mustform a flameproof joint through which no flamescan penetrate. For this reason, attention mustbe paid to the appropriate selection of cable glanddepending on both the type and structure ofcable and installation location. If the flameproofenclosure has to be used in a IIC atmosphereor if a flameproof enclosure with a volume biggerthan 2 dm3 has to be applied in Zone 1, the gas-kets or cable glands have to be sealed. The flame-proof enclosure primarily depends here on thecare taken by the electrician when connecting thecables.

    Conduit SystemIn the case of installation using the conduit sys-tem, the electrical lines are drawn as single wiresinto enclosed metal conduits. The conduits areconnected to the housings by means of fittingsand equipped with a seal at each entrance point.

    The entire conduit system is flameproof. The aimof the seal is to prevent explosions which mayoccur inside the housing from transmitting intothe conduit. Otherwise, extremely high explosionpressures would be created as a result of pre-compression in long cylindrical tubes. For thisreason, it is recommended that seals be installednot just at the entrance points but at specificintervals. Drains must be installed at low pointsat which condensate can accumulate.

    5.4 Maintenance

    Periodic maintenance is required to maintain thesafety of electrical installations in hazardousareas. Personnel who carry out such maintenancework should work under the guidance of anexplosion protection expert and should be in-formed of the particular hazards involved (skilledperson, IEC 60079-17).

    Before corrective maintenance, it must be ensuredthat there is no danger of explosions occurringduring this work. Normally, formal written work-permission for this should be acquired from thecompany management. On completion of the work,a documentation should be kept of what workwas carried out, and confirmation given that allrelevant regulations have been observed.

    A technical person with executive function shall

    be identified for each installation. He is respon-sible for the determination of the frequencyof inspection, the grade of inspection, the avail-ability of the documentation, the training for theskilled personel, etc.

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    6. explosion protection in north america3

    6. Explosion Protection in North America

    6.1 Introduction

    The basic principles of explosion protectionare the same all over the world. However, tech-nologies have developed in North America in thefield of explosion protection for electrical equip-ment and installations which deviate considerablyfrom those of the IEC (International Electrotech-nical Commission). The differences from IEC tech-nologies are among others the classification ofhazardous locations, the construction of apparatusand the installation of electrical systems.

    6.2 Classification of Hazardous Locations

    For potentially explosive atmospheres the termhazardous (classified) locations is used inNorth America. These are defined in Articles 500

    and 505 of the National Electrical Code (NEC)in the USA and in Section 18 and Annex J of theCanadian Electrical Code (CEC) in Canada.Hazardous locations are locations, where fire orexplosion hazards may exist due to flammablegases, vapours or mists (Class I), combustibledusts (Class II), or ignitable fibres or flyings(Class III).

    Based on the likelihood or risk that an ignitableconcentration of a flammable substance will bepresent the hazardous locations are traditionallysubdivided into Division 1 and Division 2.

    In 1996 the IEC classification system was intro-duced as a parallel system to the existing systemfor Class I in the USA. This system was imple-mented by the new Article 505. This now givesthe end user the possibility to choose the systemthat best suits his needs.

    The IEC zone classification for Class I was alsointroduced in Canada (CEC, 1988 edition).All newly built facilities in Canada need to beclassified according to this principle.

    The traditional North American classificationsystem divides Class I flammable gases, vapours,mists and liquids into Gas Groups A, B, C and D,and Class II combustible dusts into Groups E, Fand G.

    Group A is the most hazardous gas group in thetraditional NEC system whereas Group IIC is

    the most hazardous group in the IEC system inArticle 505 of the NEC.

    In Canada both gas grouping systems may be usedwith the zone classification system.

    The maximum surface temperature determinationgiven in the new Article 505 maintains a pureIEC approach of having main temperature classesT1 to T6 with further subdivisions of the tempera-ture classes in the Division system. In the 1998CEC, this structure T1T6 with intermediate sub-divisions was maintained.

    Table 19 in appendix 7.3 provides anoverview of the classification of hazardouslocations in North America.

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    6. explosion protection in north america2

    6.3 Regulations for Installation

    The National Electrical Code in the USA and theCanadian Electrical Code in Canada apply toelectrical apparatus and installations for hazardouslocations. These have the nature of installationregulations for electrical facilities in all locations,and refer to a number of further standards of otherinstitutions that contain specifications for theerection and construction of suitable equipment.

    The methods of installation for the zone conceptin accordance with the NEC are similar to thetraditional Class/Division system. New to the NEC1996 is the use of listed Metal Clad (MC) cablesin addition to rigid conduit and Mineral Insulatedcables in Class I, Division 1 or Zone 1.

    One significant advantage to the CEC is theincreased possibility of using cables. In contrast

    to the USA, Canada has, for some time now,also permitted the use of special cables similar tothe IEC steel-wire armoured cables.

    6.4 Construction and Design Requirements

    The regulations of the National Electrical Codeand the Canadian Electrical Code stipulate whichapparatus and types of protection may be usedin different hazardous locations.

    Various standards and regulations govern theconstruction and testing of explosion-protectedelectrical apparatus and installations inNorth America. In the USA, these are mainly thestandards issued by Underwriters Laboratories Inc.(UL), Factory Mutual Research Corporation (FM)and the International Society for Measurementand Control (ISA). In Canada, those of theCanadian Standards Association (CSA) apply.

    The tables in appendix 7.4 provide an overviewof the constructional requirements for hazardouslocations and methods of protection.

    6.5 Degrees of Protection provided byEnclosures

    As the standard IEC 60 529 defines the degreesof protection provided by enclosures, as in theUSA the degrees of protection are included in theNEMA Publication No. 250 (National ElectricalManufacturing Association). These enclosure typescannot be exactly equated with the IEC enclosureclassification designation since NEMA takesadditional environmental influences (such as cool-ing lubricant, cutting coolant, corrosion, icing, hail)into account. The tables 7.5 and 7.6 in the ap-pendix illustrate the types of protection accordingto both standards.

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    6.6 Certification and Marking

    In the USA and Canada, electrical apparatus andapparatus used in hazardous locations are, asa rule, subject to approval. Exceptions to this areitems of electrical apparatus which, due to theirdesign and the peculiar nature of the explosiveatmosphere in which they are used, cannot ignite.The responsible authorities shall decide whethersuch equipment is subject to approval.

    Equipment which has been developed andmanufactured for use in hazardous locations istested and approved in the USA and Canada by anotified testing authority. In the USA, this is forexample the Underwriters Laboratories or FactoryMutual, and in Canada the Canadian StandardsAssociation.

    In addition to data such as manufacturer, type,

    serial number, and electrical data, any data relat-ing to explosion protection must be shown onthe marking of the equipment. The requirementsfor this are specified in the NEC, the CEC aswell as the relevant apparatus regulations of thetesting authority.

    Class I, II & III, Division 1 and 2The approved electrical equipment for Class I,Class II and Class III, Division 1 and Division 2must be marked to show the followinginformation:1. Class(es), Division(s)

    (optional except for Division 2)2. Gas/dust group(s)3. Operating temperature or temperature class

    (optional T5 and T6)Example: Class I Division 1 Groups C D T4

    Class I, Zone 0, 1 and 2For equipment intended for use in Class I, Zone 0,Zone 1 or Zone 2, a distinction is made betweenDivision Equipment and Zone Equipment.

    (1)Division EquipmentEquipment approved for Class I, Division 1 and/orClass I, Division 2 shall be permitted to be markedwith the following:1. Class I, Zone 1 or Class I, Zone 22. Gas group(s) IIA, IIB or IIC3. Temperature class4. Types of ProtectionExample: Class I Zone 1 d,e IIC T4

    (2)Zone EquipmentEquipment meeting one or more types ofprotection described in Article 505 of the NECor Section 18 of the CEC shall be marked withthe following in the order shown:

    1. Class (optional in Canada)2. Zone (optional in Canada)3. AEx (USA) or Ex or EEx (Canada)4. Type(s) of protection5. Equipment group II or applicable gas group(s)

    IIA, IIB or IIC6. Temperature classExample: Class I Zone 0 AEx ia IIC T6

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    Table 17:Electrical Apparatus for Use in the Presence of Combustible Dust

    IEC (new) IEC (old) EN (new) EN (old)

    General requirements IEC 61241-0 IEC 61241-1-1 EN 61241-0 EN 5028

    Protected by enclosures tD IEC 61241-1 IEC 61241-1-1 EN 61241-1 EN 502

    Pressurized enclosures pD IEC 61241-4 EN 61241-4

    Classification of potentially explosive dust atmospheres IEC 61241-10 EN 61241-10

    Intrinsic Safety iD IEC 61241-11 EN 61241-5 EN 61241-11

    Selection and installation IEC 61241-14 EN 61241-14

    Inspection and maintenance of electrical installations IEC 61241-17 EN 61241-17in hazardous areas (other than mines)

    Encapsulation mD IEC 61241-18 EN 61241-18

    Test methods: minimum ignition temperature IEC 61241-2-1 EN 50281

    Test methods: resistivity of dust in layers IEC 61241-2-2 EN 61241-2-2

    Test methods: minimum ignition energy IEC 61241-2-3

    Comments on the tables 16 and 17:IEC/EN 6124 and IEC/EN 60079 standards will be summerized in the series IEC/EN 60079 standards e.g. IEC 61241-1 will be classified as IE some of the standards are in preparation!

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    7. appendix6

    7.2 Safety Characteristics of Flammable Gases and Vapours

    Table 18:Safety Ratings: Ignition Temperature, Temperature Class and Explosion GroupMaterial Ignition Temperature C Temperature Class Explosion Group1,2-Dichloroethane 440 T 2 II AAcetaldehyde 155 T 4 II AAcetic acid 485 T 1 II AAcetic anhydride 330 T 2 II AAcetone 535 T 1 II AAcetylene 305 T 2 II C3

    Ammonium 630 T 1 II ABenzene 555 T 1 II ACarbon disulphide 95 T 6 II C1

    Carbon monoxide 605 T 1 II ACyclohexanone 430 T 2 II ADiethyl ether 175 T 4 II BDiesel fuels 220 T 3 II AEthane 515 T 1 II AEthanol 400 T 2 II BEthene 440 T 2 II BEthyl chloride 510 T 1 II A

    Ethyl ethanoate 470 T 1 II AEthyl glycol 235 T 3 II BEthylene oxide 435 (self-decomposing) T 2 II BFuel oil EL, L, M, S 220 to 300 T 3 II AHydrogen 560 T 1 II C2

    Hydrogen sulphide 270 T 3 II Bi-Amyl acetate 380 T 2 II AMethane 595 T 1 II AMethanol 440 T 2 II AMethyl chloride 625 T 1 II ANaphthalene 540 T 1 II A

    n-Butane 365 T 2 II An-Butanol 325 T 2 II Bn-Hexane 230 T 3 II An-Propyl alcohol 385 T 2 II B*

    Petrol fuels 220 to 300 T 3 II APhenol 595 T 1 II APropane 470 T 1 II AToluene 535 T 1 II A

    *The gas group for this substance has not yet been determined.1Also gas groups II B + CS22Also gas groups II B + H23Also gas groups II B + C2 H2

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    7.3 Classification of Hazardous Locations in North America

    Table 19:Classification of Hazardous Locations in North AmericaGases, vapors or mists Dusts Fibres and flyingsClassification Class I

    NEC 500-5CEC J18-004Division 1Locations where ignitible concen- trations of flammable gasesor vapors can exist under normaloperating conditions as wellas frequently because of repair ormaintenance operations or becauseof leakage.

    Division 2Locations where ignitible concen- trations of flammable gases orvapors can exist under abnormaloperating conditions.

    Class I GroupsNEC 500-3CEC J18-050Division 1 and 2A (Acetylene)B (Hydrogen)C (Ethene)D (Propane)Class I Temperature classesDivision 1 and 2

    T1 ( 450C, 842F)T2 ( 300C, 572F)T2A, T2B, T2C, T2D( 280C, 260C, 230C, 215C)(536 F, 500F, 446 F, 419F)T3 ( 200C, 392F)T3A, T3B, T3C( 180C, 165C, 160C)(356F, 329F, 320F)T4 ( 135C, 275F)T4A ( 120C, 248F)T5 ( 100C, 212F)T6 ( 85C, 185C)

    NEC 505-7CEC 18-006Zone 0Locations where ignitible concen- trations of flammable gasesor vapors are present continuouslyor for long periods of time.

    Zone 1Locations where ignitable concen- trations of flammable gases orvapors are likely to exist under nor-mal operating conditions or mayexist frequently because of repair ormaintenance or because of leakage.Zone 2Locations where ignitible concen- trations of flammable gasesor vapors are not likely to occur innormal operation, and if they do,will exist only for a short period.

    NEC 505-7CEC J18-050Zone 0, 1 and 2IIC (Acetylene + Hydrogen)

    IIB (Ethene)IIA (Propane)

    Zone 0, 1 and 2

    T1 ( 450C)T2 ( 300C)

    T3 ( 200C)

    T4 ( 135C)

    T5 ( 100C)T6 ( 85C)

    NEC 500-6CEC 18-008Division 1Locations where ignitible concen- trations of combustible dust isin the air under normal operatingconditions.

    Division 2Locations where ignitible concen- trations of combustible dust isin the air under abnormal operatingconditions.

    Class II GroupsNEC 500-3CEC J18-050Division 1 and 2E (Metal)F (Coal)G (Grain)

    Class II Temperature classesDivision 1 and 2

    T1 ( 450C, 842F)T2 ( 300C, 572F)T2A, T2B, T2C, T2D( 280C, 260C, 230C, 215C)(536 F, 500F, 446 F, 419F)T3 ( 200C, 392F)T3A, T3B, T3C( 180C, 165C, 160C)(356F, 329F, 320F)T4 ( 135C, 275F)T4A ( 120C, 248F)T5 ( 100C, 212F)T6 ( 85C, 185C)

    Fibres and flyingsClassification Class IIIDivision 1Locations where easily ignitiblefibres or materials producingcombustible flyings are handled,manufactured or used.

    Division 2Locations where easily ignitiblefibres and materials producingcombustible flyings are stored orhandled other than in the processof manufacture.

    Class III

    Division 1 and 2none

    Class III TemperatureDivision 1 and 2

    none

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    7. appendix8

    7.4 Constructional Requirements for Explosion Protected Electrical Equipment

    Table 20:Constructional Requirements in Europe, USA, Canada, and International Comparison, Part 1

    Type of ignition protection Abbreviation Region Installation location Standard

    General requirements US Class I, Division 1 & 2 FM 3600AEx US Class I, Zone 0, 1, & 2 ISA 60079-0Ex CA Class I, Zone 0, 1, & 2 CSA E60079-0Ex (EEx) EU Zone 0, 1 & 2 EN 60079-0Ex IEC Zone 0, 1 & 2 IEC 60079-0

    Increased safety AEx e US Class I, Zone 1 ISA 60079-7Ex e CA Class I, Zone 1 CSA E60079-7Ex e (EEx e) EU Zone 1 EN 60079-7Ex e IEC Zone 1 IEC 60079-7

    Non-incendive (NI) US Class I, Division 2 FM 3611(NI) CA Class I, Division 2 C22.2 No. 213

    Non-sparking apparatus AEx nA US Class I, Zone 2 ISA 60079-15Ex nA CA Class I, Zone 2 CSA E60079-15Ex nA (EEx nA) EU Zone 2 EN 60079-15Ex nA IEC Zone 2 IEC 60079-15

    Explosion-proof (XP) US Class I, Division 1 FM 3615(XP) CA Class I, Division 1 C22.2 No. 30

    Flameproof enclosure AEx d US Class I, Zone 1 ISA 60079-1Ex d CA Class I, Zone 1 CSA E60079-1Ex d (EEx d) EU Zone 1 EN 60079-1Ex d IEC Zone 1 IEC 60079-1

    Powder filling AEx q US Class I, Zone 1 ISA 60079-5Ex q CA Class I, Zone 1 CSA E79-5Ex q (EEx q) EU Zone 1 EN 50017Ex q IEC Zone 1 IEC 60079-5

    Protected facilities AEx nC US Class I, Zone 2 ISA 60079-15and components Ex nC CA Class I, Zone 2 CSA E60079-15

    Ex nC (EEx nC) EU Zone 2 EN 60079-15Ex nC IEC Zone 2 IEC 60079-15

    Intrinsic Safety (IS) US Class I, Division 1 FM 3610(IS) CA Class I, Division 1 C22.2 No. 157AEx ia US Class I, Zone 0 FM 3610AEx ib US Class I, Zone 1 FM 3610Ex ia CA Class I, Zone 0 CSA E60079-11Ex ib CA Class I, Zone 1 CSA E60079-11Ex ia (EEx ia) EU Zone 0 EN 60079-11Ex ic EU Zone 2 EN 60079-11Ex ib (EEx ib) EU Zone 1 EN 60079-11Ex ia IEC Zone 0 IEC 60079-11Ex ic IEC Zone 2 IEC 60079-11Ex ib IEC Zone 1 IEC 60079-11

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    Table 21:Constructional Requirements in Europe, USA, Canada and International Comparison, Part 2

    Type of ignition protection Abbreviation Region Installation location Standard

    Energy-limited apparatus AEx nC US Class I, Zone 2 ISA 60079-15Ex nL CA Class I, Zone 2 CSA E60079-15Ex nL (EEx nL) EU Zone 2 EN 60079-15Ex nL IEC Zone 2 IEC 60079-15

    Pressurized enclosure Type X US Class I, Division 1 FM 3620

    Type X CA Class I, Division 1 NFPA 496Type Y US Class I, Division 1 FM 3620Type Y CA Class I, Division 1 NFPA 496Type Z US Class I, Division 2 FM 3620Type Z CA Class I, Division 2 NFPA 496AEx px US Class I, Zone 1 ISA 60079-2Ex px CA Class I, Zone 1 CSA E60079-2Ex px (EEx px) EU Zone 1 EN 60079-2Ex px IEC Zone 1 IEC 60079-2AEx py US Class I, Zone 1 ISA 60079-2Ex py CA Class I, Zone 1 CSA E60079-2Ex py (EEx py) EU Zone 1 EN 60079-2Ex py IEC Zone 1 IEC 60079-2AEx pz US Class I, Zone 2 ISA 60079-2Ex pz CA Class I, Zone 2 CSA E60079-2Ex pz (EEx pz) EU Zone 2 EN 60079-2Ex pz IEC Zone 2 IEC 60079-2

    Purged/pressurized AEx nR US Class I, Zone 2 ISA 60079-15Ex nR CA Class I, Zone 2 CSA E60079-15Ex nR (EEx nR) EU Zone 2 EN 60079-15Ex nR IEC Zone 2 IEC 60079-15

    Encapsulation Ex ma (EEx ma) EU Zone 0 EN 60079-18Ex ma IEC Zone 0 IEC 60079-18AEx m US Class I, Zone 1 ISA 60079-18Ex m CA Class I, Zone 1 CSA E60079-18

    Ex mb (EEx mb) EU Zone 1 EN 60079-18Ex mb IEC Zone 1 IEC 60079-18

    Oil immersion AEx o US Class I, Zone 1 ISA 60079-6Ex o CA Class I, Zone 1 CSA E79-6Ex o (EEx o) EU Zone 1 EN 50015Ex o IEC Zone 1 IEC 60079-6

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    7. appendix0

    7.5 Degrees of Protection according to IEC 60 529 - IPXX

    Table 22:Degrees of Protection according to IEC 60 529 - IPXXDigit First digit Second digit

    Physical protection Foreign body protection Water protection

    0 No protection No protection No protection

    1 Protection against back of hand contact Protection against solid foreign bodies 50 mm Protection against water drops falling vertically

    2 Protection against finger contact Protection against solid foreign bodies 12.5 mm Protection against water drops falling atan angle (15)

    3 Protection against contact from tools Protection against solid foreign bodies 2.5 mm Protection against water-spray at an angleup to 60

    4 Protection against contact with a wire Protection against solid foreign bodies 1.0 mm Protection against water spray from all directions

    5 Protection against contact with a wire Protection against dust Protection against water jets

    6 Protection against contact with a wire Dust-tight Protection against strong water jets

    7 Protection against intermittent immersion in water

    8 Protection against continuous immersion in water

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    Table 23:Degree of Protection provided by Enclosures according to NEMA (Publication No. 250 Enclosures for Electrical Equipment 1000Volts Maximum)

    Digit Degree of Protection Use

    Type 1 Protection against incidental contact with the enclosed equipment. Indoor

    Type 2 Protection against limited amounts of falling water and dirt. Indoor

    Type 3 Protection against rain, sleet, windblown dust, and damage from external ice formation Outdoor

    Type 3R Protection against rain, sleet, and damage from external ice formation. OutdoorType 3S Protection against rain, sleet, windblown dust, and for operation of external mechanisms when ice laden. Outdoor

    Type 4 Protection against, rain, splashing water, hose directed water, and damage from external ice formation. Indoor or outd

    Type 4X Protection against, rain, splashing water, hose directed water, and damage from external ice formation. Indoor or outProtection against corrosion.

    Type 5 Protection against settling airborne dust, falling dirt, and dripping non-corrosive liquids. Indoor

    Type 6 Protection against hose directed water, penetration of water during occasional temporary submersion at a Indoor or outdlimited depth, and damage from external ice formation.

    Type 6P Protection against hose directed water, penetration of water during prolonged submersion at a limited depth, Indoor or outand damage from external ice formation.

    Type 7 For use in locations classified as Class I, Groups A, B, C or D as defined in the NEC. Indoor

    Type 8 For use in locations classified as Class I, Groups A, B, C or D as defined in the NEC. Indoor or out

    Type 9 For use in locations classified as Class II, Groups E, F or G as defined in the NEC. Indoor

    Type 10 Constructed to meet the applicable requirements of the Mine Safety Health Administration. Mining

    Type 11 Protection against the corrosive effects of liquids and gases by oil immersion. Indoor

    Type 12, 12K Protection against circulating dust, falling dirt, and dripping non-corrosive liquids. Indoor

    Type 13 Protection against dust, splashing water, oil, and non-corrosive liquids. Indoor

    7.6 Degrees of Protection according to NEMA Standards

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    8. literatureexplosion protection

    2

    8. Literature

    Directive 94/9/EU of the European Parliament andthe council of 23 March 1994 on the approxima-tion of the laws of the member states concerningequipment and protective systems intended foruse in potentially explosive atmospheres.Official Journal of the European Communities,No. L 100/1

    The Equipment and Protective Systems for Usein Potentially Explosive Atmospheres Regulations,1996 (EPS), ATEX 95 (UK). Explosionsschutzver-ordnung (ExVO) Verordnung ber das Inverkehr-bringen von Gerten und Schutzsystemen frexplosionsgefhrdete Bereiche. 11. GPSV(Explosion Protection Regulation). Germany

    Directive 99/92/EC on the Minimum requirementsfor improving the health and safety protection

    of the worker at risk from explosive atmospheres16/12/1999, Official Journal of the EuropeanCommunities, L23/5764

    The Dangerous Substances and Explosive Atmo-spheres Regulations 2002, Statutory Instrument2002 No. 2776 (UK). Verordnung ber Sicherheitund Gesundheitsschutz bei der Bereitstellung vonArbeitsmitteln und deren Benutzung bei der Arbeit,ber Sicherheit beim Betrieb berwachungs-bedrftiger Anlagen und ber die Organisation desbetrieblichen Arbeitsschutzes Betriebssicher-heitsverordnung (BetrSichV) (Regulation on safetyand health protection in the provision of workequipment and its use, on safety when operatinginstallations requiring special state regulation andsupervision and on the organisation of safety atwork) Germany

    Regeln fr das Vermeiden der Gefahren durchexplosionsfhige Atmosphre Explosionsschutz-regeln (ExRL) (Rules for the avoidance of hazardsfrom explosive atmospheres Explosion ProtectionRules) published by the Hauptverband dergewerblichen Berufsgenossenschaften,Fachausschuss Chemie der BGZ, BGR 104

    E. Brandes, W. MllerSicherheitstechnische Kenngren Band 1:Brennbare Flssigkeiten und Gase(Safety Characteristics Vol. 1:Flammable Liquids and Gases)Wissenschaftsverlag NWVerlag fr neue Wissenschaft GmbH

    Molnrn, Schendler, SchrderSicherheitstechnische Kenngren Band 2:Explosionsbereiche von Gasgemischen(Safety Characteristics: Vol. 2:

    Explosion regions of gas mixtures)Wissenschaftsverlag NWVerlag fr neue Wissenschaft GmbH

    M. Hattwig, H. SteenHandbook of Explosion Prevention and ProtectionWiley VCH, 2004, ISBN 3527307184

    IEC 60079 or EN 60079 seriesElectrical apparatus for explosive gas atmospheresVDE-Verlag GmbH, Berlin

    IEC 61241 and EN 61241 seriesElectrical apparatus for use in the presence ofcombustible dust

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    EN 60 529Specification for degrees of protection provided byenclosures (IP code)

    EN 13463 Part 1 Part 8Non-electrical equipment for potentially explosiveatmospheres

    Dust explosion prevention and protectionfor machines and equipmentISSA Prevention Series No. 2033 (G)

    Dust explosionsISSA Prevention Series No. 2044 (G)

    The basics of dust explosion protectionR. STAHL Schaltgerte GmbH

    Operators of electrical installations inplants with potentially explosive atmosphere

    R. STAHL Schaltgerte GmbH

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    SerbiaKEYING d.o.o.Vuka Kara zdica 7923300 KikindaTel. +381 230 401770Fax +381 230 401790E-mail: [email protected]

    SlovakiaHAGARD:HALPrazska 694911 NitraTel. +421 37 7913000Fax +421 37 7411508

    SloveniaSYNATEC d.o.o.

    Vojkova ulica 8B5280 IdrijaTel. +386 5 3720650Fax +386 5 3720660

    SpainINDUSTRIAS STAHL S.A.Aragoneses, 2 Acceso 10Poligono Industrial28108 Alcobendas (Madrid)Tel. +34 91 6615500Fax +34 91 6612783E-mail: [email protected]

    SwedenR.STAHL SVENSKA ABBagspnnarvgan 1417568 JrfllaTel. +46 8 389100Fax +46 8 389198

    SwitzerlandSTAHL-Fribos AGIndustriestr. 265070 FrickTel. +41 62 86540-60Fax +41 62 86540-80E-mail: [email protected]

    Republic of South AfricaESACO Pty. Ltd.P.O. Box 30951610 EdenvaleTel. +27 11 6083100Fax +27 11 6083165E-mail: [email protected]

    [email protected]

    Ukraine

    DONETSK ENGINEERING GROUP17, 50th Gvardeyskaya Diviziya str.83052 DonetskTel. +380 62 3828977Fax +380 62 3828412E-mail: [email protected]

    America

    ArgentinaNORRI S.R.L.Bogota 23841640 MartinezPcia. Buenos AiresTel. +54 11 4717-6991, -6334Fax +54 11 4798-6991, -6334

    BrazilInstrumentos Lince LTDA.Rua Luiz Ferreira, 84Bonsucesso21042 - 210 Rio de Janeiro - RJTel. +55 21 25732344

    Fax +55 21 25615326ChileINGENIERIA DESIMAT LTDA.Av. Puerto Vespucio9670 Pudahuel SantiagoTel. +56 2 7470152Fax +56 2 7470153

    ColombiaAutomatizacin Avanzada S.A.Carrera 98 No. 41A-23, Bodega 3Santafe de BogotaTel. +57 1 4188867, 4132324Fax +57 1 4159788

    MexicoImplementos y ServiciosElectrnicos S.A. de C.V. (ISEL)Via Lopez Mateos No. 128Col. JacarandasC.P. 54050 TlalnepantlaEstado de MexicoTel. +52 55 5398-8088Fax +52 55 5397-3985E-mail: [email protected]

    PeruDESIMAT PERU SACAv. Velasco Astete 2371Surco-LimaTel. +51 1 2752765Fax +51 1 2752776E-mail: [email protected]

    USA/CanadaR.STAHL Inc.9001 Knight Rd.Astro Business CenterHouston, Tx 77054Tel. +1 713 7929300Fax +1 713 7929301E-mail: [email protected]

    VenezuelaTEXCA C.A.Edificio LIPESA, Piso 3, Oficina 32Avenida Orinoco, Bello MonteCaracasTel. +58 212 9532769Fax +58 212 9521504

    Asia

    Abu DhabiAl Sahwa Trading Co. L.L.C.P.O. Box 45491Abu DhabiTel. +971 2 6273270Fax +971 2 6270960E-mail: [email protected]

    AustraliaNHP Electrical EngineeringProducts Pty. Ltd.43-67 River StreetRichmond Victoria 3121Tel: +61 3 9429 2999

    Fax +61 3 9429 1075E-mail: [email protected]

    BruneiAisha Automation CompanyNo.137, Lot 4034Jalan Jaya NegaraKuala Belait KA1931P.O. Box 629, Kuala belait KA1131Negara Brunei DarussalamTel. +673 3331312, 3342529Fax +673 3342529E-mail:[email protected]

    P.R. ChinaR.STAHL EX-PROOF CO. Ltd.(SHANGHAI)Unit D, 9th Floor, Building No. 4889 Yishan RoadShanghai 200233Tel. +86 21 64850011Fax +86 21 64852954E-mail: [email protected]

    IndiaR.STAHL (P) Ltd.9, Arcot RoadLakshmi Nagar, PorurChennai 600 116Tel. +91 44 24766674Fax +91 44 24767835E-mail: [email protected]

    IndonesiaPT MUSTIKA STAHLJl. Griya Agung No. 81Griya Inti Sentosa Sunter AgungJakarta 14350Tel. +62 21 6450574Fax +62 21 6404249E-mail: [email protected]

    PT ULTRA DELTA MAJUKedoya Elok PlazaBlok DD No. 5960Jl. Panjang Kebon JerukJakarta 11520Tel. +62 21 58300678Fax +62 21 58300686, -87

    PT Maxima Pro Corpora(Instrumentation only)GEDUNG PESONA 1st Floor,Suite 102 Jl. Ciputat Raya No. 20Tanah Kusir, Kebayoran LamaJakarta Selatan 12310Tel. +62 21 7292 158Fax +62 21 7292 159E-mail:[email protected]

    PT Prakarsa Daya Juang(Switchgear & Lighting)Wisma Kosgoro16th Floor, Suite 1603JL MH Thamrin Kav 49Jakarta 10350Tel. +62 21 3983 6063Fax +62 21 3983 6062

    IranTBN Co.Apt. 13, 7th Floor, No. 92West Sepand St, South Aban AveKarim Khan Zand BlvdTehranTel. +982 188 927 264E-mail: [email protected]

    JapanR.STAHL K.K. Co. Ltd.Sinyurigaoka City Bldg. 4F1-1, Manpukuji 1-chome, Asou215-0004 Kawasaki-shi,KanagawaTel. +81 44 9592612Fax +81 44 9592605E-mail:[email protected]

    KoreaR.STAHL Co. Ltd.No. 503 Keang Nam Bldg. #163-16 Sung Nae-DongKang Dong-KuSeoulTel. +82 2 4708877Fax +82 2 4718285E-mail: [email protected]

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    9. adressesexplosion protection

    6

    KuwaitRezayat Trading CompanyP.O. Box 106Safat 13002KuwaitTel. +965 481 6838E-mail:[email protected]

    MalaysiaESTEEM LINK (LU) SDN BHD.(Agent for East Malaysia:Switchgear&Lighting)321, Jalan Nahkoda Gampar,PO Box 1140,98008 Miri, SarawakTel. +60 85 417230

    Fax +60 85 414352E-mail: [email protected]

    EMPIRE ENGINEERING SDN BHD.(Agent for West Malaysia:Switchgear & Lighting)Unit D3A02, Kelana Square17, Jalan SS7/26, Kelana Jaya47301 Petaling Jaya, SelangorTel. +60 37803 1477Fax +60 37803 1377E-mail: [email protected]

    VECTOR INFOTECH SDN BHD(Instrumentation only)Block C-5-7 & 8 (Level 7)UE3 Menara Uncang EmasNo. 85, Jalan Loke Yew55300 Kuala LumpurTel. +60 3 92001396/1397Fax +60 3 92001398E-mail: [email protected]

    New ZealandELECTROPAR Ltd.P.O. Box 58623GreenmountAuckland 1701Tel. +64 9 2742000Fax +64 9 2742001E-mail: [email protected]

    OmanAl Hassan Group of CompaniesP.O. Box 1948Postal Code 112RuwiTel. +968 248 10575-209E-mail: [email protected]

    PakistanClipsal Pakistan (PVT) Ltd.101102, Sector 15Korangi Industrial EstateKarachiTel. +92 21 5067278Fax +92 21 5063369

    PhilippinesMATERIALS UNLIMITEDCORPORATIONNo. 2 Congressional AvenueProject 6, Quezon CityTel. +63 2 4263856/57Fax +63 2 9248664E-mail: matcor@p