Source: https://fr.scribd.com/document/83031433/Ex-Protection
Timestamp: 2019-07-22 12:06:12
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Ex Protection | Inflammabilité | Combustion
Transféré par Anil Markale
enregistrerEnregistrer Ex Protection pour plus tard
1-s2.0-S1877705813012538-main
NIST.TN.1791
Design to Prevent Fires and Explosion
CH 23.NFPA.ratings[1]
The brochure was put together carefully in conformance to the current status of standards and regulations. The respective amended version of the technical and statutory rules is binding. Errors and misprints do not justify any claim for damages. All rights reserved, in particular the rights of duplication, distribution and translation. BARTEC brochure Basic concepts for explosion protection - 10. revised edition - Version 2011
Technical development of explosion protection Explosion protection
Explosion Basis for an explosion Explosive range Prevention of explosions Primary explosion protection Three factors Flammable substances Oxygen Ignition sources 2 4 - 10 4 4 4 5 5 6 6 7 8 - 10 11 - 24 11 12 12 13 - 17 18 19 20 - 22 23 - 24
Overview Non-technical measures Design regulations Regulations Relevance and advantage of the classification zone Explosion parameters Ignition temperature - Gases/Vapors/Dusts Explosion sub-group - Minimum ignition current ratio - Dust conductivity - Classification by MESG
General requirements Flameproof enclosures Enclosed break device Non-incendive component Pressurized enclosures Powder filling Oil/ Liquid immersion Increased safety Non sparking device Protection by constructional safety Encapsulation Hermetically sealed device Encapsulated device Sealed device Protection by enclosures Intrinsically safe Energy limitation Protection by control of ignition sources Restricted breathing enclosure Special protection Ex d Ex nC Ex nC Ex p, px, py, pz Ex q Ex o, k Ex e Ex nA c Ex m Ex nC Ex nC Ex nC Ex t Ex i Ex nL b Ex nR, fr Ex s
25 - 34 25 26 27 27 28 29 29 30 30 30 31 31 32 32 32 33 33 34 34 34 35 - 39 35 - 38 39 40 40 40
Contents of marking -Conformity
Directive 94/9/EC Directive 1999/92/EC
After bitter experiences in the beginning, the occurrence of firedamp explosions was greatly reduced and well-monitored electrical equipment was utilised with very high safety standards.
Today, fortunately, the number of accidents caused by electrical ignition sources is low. The expenditure on development and manufacturing and the statutory regulations have proven to be successful and the frequently posed question as to "whether such expenditures are justified must be answered with yes. Any neglect would equal culpable carelessness. Unfortunately there are still numerous examples of explosions that demonstrate the devastating effects on humans and plants.
Personal responsibility and precautionary measures
Solutions concerning sources of ignition are referred to as secondary explosion protection and priority is given to what is regarded as primary explosion protection, i. e. the focussing of attention on the use of non-flammable substances that are not capable of forming an explosive atmosphere.
However, it is not always possible to exclude flammable substances such as methane or coal dust in mines, or petrol and in future perhaps hydrogen in vehicles. In such cases protection and safety are provided by equipment which is reliably explosion proof.
These days, the construction of explosion proof equipment goes far beyond the field of electrical engineering. As will be demonstrated in the further descriptions, in future non-electrical equipment will also require testing or at least assessment. Here the knowledge gained by manufacturers over the decades on the explosion proof electrical equipment is particularly important and it now also benefits the manufacturers of non-electrical equipment. These manufacturers often buy electrical equipment, which automatically creates a contact.
There are many applications which require explosion proof equipment. During the over 100 years of electrical explosion protection, principles and techniques have been developed which allow the use of electrical measuring technology, even where, e. g. in reaction vessels, an explosive atmosphere is permanently present.
The applications in the mining area were the beginning. The utilisation and processing of mineral oil and natural gas offer a wide scope for using explosion proof equipment. Organic chemistry, the paint industry and the pharmaceutical industry all process flammable liquids and gases. Because of the production and utilisation of biogas and the ecological utilisation of waste dumps, new applications are constantly developing. The utilisation of hydrogen is being discussed in depth, practised in experimental installations and exhibited at trade fairs.
In the Directive 94/9/EC the European Community has provided itself with obligatory, uniform design requirements for the explosion protection of systems, equipment and components and this directive is supported by the EN standards referred to in the above and the CENELEC and CEN standardisation organisation.
With the help of these standards, the manufacturer can assume during the design and assessment of the explosion protection that he is developing safe, explosion proof systems, equipment and components conforming to Directive 94/9/EC which will be tested in conformance to uniform and obligatory criteria by a notified body authorized by the EC. If the test criteria have been met successfully, the EC-appointed notified bodie issue the type examination certificates, which ensure standard fullfillment in Europe with respect to the required safety of the explosion proof equipment. These EC type examination certificates, or assessments provided by the manufacturer, are the prerequisite for the production and distribution of systems, equipment and components at a very high or high level of protection.
The same uniform quality requirements are also required under Directive 94/9/EC for the type of the installation and for the servicing required for maintaining the safe state. The technical parameters are also defined in EN standards.
Uniform classification of the potentially explosive atmospheres (plants) is the basis for the selection and classification of systems and equipment, including their installation. The appropriate EN standards are being developed and passed step by step as Directive 1999/92/EC is becoming adopted. According to this EC Directive, an Ex document is a precondition for setting up and operating a potentially explosive facility. Only such a document makes it possible to select systems, equipment and components with regard to explosion protection and to install, operate, maintain and eventually repair them as required by the standards.
The directives are incorporated in national regulations in Germany, e. g. in the GPSG Gerte-und Produktsicherheitsgesetz and the BetrSichV Betreibssicherheitsverordnung. The 94/9/EC Directive formulates uniform binding requirements, while the national implementation of the 1999/92/EC Directive contains the minimum requirements, which can be made more stringent on a national level.
Using the two Directives mentioned above, a consistent system is created which allows successful prevention of explosions for the effective protection of people, the environment and property.
BARTEC develops and constructs safety systems, equipment and components, develops solutions and projects and realises them.
Our corporate goal is: BARTEC protects people and the environment by the safety of components, systems and plants.
As a rule, for explosions to happen in atmospheric air, three factors have to be present at the same time: flammable substance oxygen (air) source of ignition
In production and work places, hazardous areas can develop wherever the first two preconditions for an explosion are fulfilled. Typical hazardous areas form in chemical factories, refineries, enamelling plants, paint workshops, cleaning equipment, mills and stores for milled products and other combustible dusts, in tank facilities and loading areas for flammable gases, liquids and solids. The first two factors - the flammable substance and air - must be present in sufficient quantities to form an explosive atmosphere. The statutory definitions of explosion protection - derived from the health and safety at work regulations - are concerned with workplaces. For this reason, explosion protection is generally limited to description of reactions with oxygen in the air. Oxidation reactions normally involve increases in heat and pressure and therefore fulfil the criteria of an explosion. It is generally assumed that a volume of 10 l of an explosive mixture in an enclosed space can cause damage - particularly to people. For this reason, any area in which such a volume of an explosive mixture can collect is described as a potentially explosive atmosphere. Other compounds such as chlorine in reaction with hydrogen are also capable of forming explosive mixtures and have already led to explosions in the past. However, as these reactions usually take place inside containers or reactors, they concern the safety of these facilities and their effects on the environment are therefore dealt with in the EC machinery directive and incident analysis.
In the internal combustion engine the three factors work together effectively: petrol, air/oxygen and the ignition spark produce an explosion inside the enclosed cylinder. For this to take place, the ratio of petrol to air must be correct. If the petrol tank is empty, the air filter blocked or if the ignition does not work, one of the components for triggering this controlled, useful explosion is missing and the motor will not start. Combustible materials mixed with air have a lower and an upper explosive limit and the explosive range lies between these limits. When considering the safety of work places, the lower explosive limit is the more important value, a possible concentration of at least 20 % less than that value is often regarded as safe.
Explosion proof equipment is able to exclude one of the preconditions for an explosion - the ignition source - and is in that way an important contribution to explosion protection. In domestic areas, constructional measures ensure that normally an explosive atmosphere cannot form. The conscious restriction of these measures, e. g. the intended, unimpeded flow of flammable gases or a reduction in ventilation can lead to explosions if an ignition source is also present. The easiest and simplest way to understand small and safe explosions is by looking at a gas lighter. When the nozzle of the lighter is opened, it releases a small amount of flammable gas. This gas mixes with the surrounding air, the spark from the flint ignites the mixture, and a weak sound is heard - the burning. Some distance away from the nozzle the proportion of the flammable gas is already so low that the explosion and the flame are restricted to the immediate vicinity of the nozzle. In other words, the design of the gas lighter has ensured that it is safe to use. The effect of an explosion in enclosed spaces and under non-atmospheric conditions - e. g. under increased pressure - is often more powerful. Just think of the useful application of explosions in vehicle engines. To attain effective explosion protection against non-controlled, unintended explosions linked to disastrous consequences, it is necessary to remove one of the three factors. BARTEC products prevent ignition sources or coming together of such sources with potentially explosive atmospheres. They effectively prevent explosions because the other two factors - the oxygen in the air and often the flammable substance - cannot be reliably and permanently ruled out in workplaces.
Primary explosion protection aims at substituting something else for the flammable substances or the atmospheric oxygen or reducing their quantities to the point where there is no danger of an explosive mixture forming. Increased air circulation, air flushing through ventilation can be achieved by structural measures; e. g. the open layout of filling stations where the potentially explosive atmosphere is very small. Replacing the atmospheric oxygen is not an option for areas where people work. For this reason the measures available for such locations are limited to: avoidance or restriction of flammable substances which are capable of forming an explosive atmosphere avoidance or restriction of release of the flammable substances and therefore formation of explosive mixtures, both inside and around fittings, e. g. by - limiting their concentration - using enclosures filled with an inert substance - natural or artificial ventilation - concentration monitoring by means of a gas detection system, which will give an alarm/or switch off the system
Three factors Flammable substances
Flammable substances can be gaseous, liquid or solid. For a general discussion relevant to work places, their reactivity with atmospheric oxygen is considered.
A flammable gas may be an element such as hydrogen which can be made to react with oxygen with very little additional energy. Flammable gases are often compounds of carbon and hydrogen. These flammable gases and vapours require only small amounts of energy to react with atmospheric oxygen. A vapour is the proportion of a liquid - if talking about the explosion protection of flammable liquids - which has evaporated into the surrounding air as the result of the vapour pressure above the surface of the liquid, around a jet of that liquid or around droplets of the liquid. Mist is a special type, which because of its explosion behaviour, can be included with the vapours, for the purposes of fulfilment of safety considerations.
Flammable liquids are often hydrocarbon compounds such as ether, acetone or petroleum spirit. Even at room temperature, sufficient quantities of these can change into the vapour phase so that an explosive atmosphere forms near their surface. Other liquids form such an atmosphere near their surface only at increased temperatures. Under atmospheric conditions this process is strongly influenced by the temperature of the liquid.
For this reason the flash point, or rather the flash point temperature, is an important factor when dealing with flammable liquids. The flash point relates to the lowest temperature at which a flammable liquid will, under certain test conditions, form a sufficient quantity of vapour on its surface to enable an effective ignition source to ignite the vapour air mixture.
The flash point is important for the classification of potentially explosive atmospheres. Flammable liquids with a high flash point are less dangerous than those with a flash point at room temperature or below. When spraying a flammable liquid, a mist can form consisting of very small droplets with a very large overall surface area, as is well-known from spray cans or from car spraying stations. Such a mist can explode. In this case the flash point is of lesser importance. For a fine mist - made from a flammable liquid - the behaviour relevant to safety can be roughly derived from the known behaviour of the vapour.
Flammable solids Flammable solids in the form of dust or flyings can react with atmospheric oxygen and produce disastrous explosions. Normally more energy is required for activating the explosion in air than with gases and vapours. However, once combustion starts, the energy released by the reaction produces high temperatures and pressures. In addition to the chemical properties of the solid itself, the fineness of the particles and the overall surface area, which increases with increasing fineness, play an important part. The properties are processes which take place immediately at the surface of the solid. Lighting and extinguishing a paraffin wax candle provides a demonstration of a series of processes undergone by a solid material within a short period of time which cannot easily be presented in a simplified form. An experiment shows that when the wick of a candle is lit, the paraffin wax melts and then vaporises and that this vapour feeds the flame. After extinguishing the candle, the paraffin vapour can still be smelled, the melted paraffin wax solidifies and the paraffin vapours disperse. Now the paraffin wax candle is once again a harmless object. Dust reacts very differently, depending on whether it is in a deposited layer or whether it is in a suspended dust cloud. Dust layers are liable to begin smouldering on hot surfaces, while a dust cloud which has been ignited locally or through contact with a hot surface can explode immediately. Dust explosions are often the consequence of smouldering dust layers which become stirred up and already carry the ignition initiation. When such a layer is stirred up, for example by mechanical cleaning methods during transportation or inappropriate extinguishing attempts, this can lead to a dust explosion. A gas or vapour/air explosion can also stir up the dust, which then often leads to the first, the gas explosion, turning into the second, the dust explosion. In deep coal mines methane/firedamp explosions often have triggered off coal dust explosions whose consequences were more serious than those of the original firedamp explosion.
Wood-Dust Sugar dust
The quantity of oxygen available in the air can only oxidise/burn a certain quantity of the flammable material. The ratio can be determined theoretically, it is called the stoichiometric mixture. When the quantity of the flammable material and the available atmospheric oxygen are near to at the correct ratio, the effect of the explosion - temperature and pressure increase - is most violent. If the quantity of flammable material is too small, combustion will only spread with difficulty or will cease altogether. The situation is similar when the quantity of flammable material is too great for the amount of oxygen available in the air. All flammable materials have their explosive range, which also depend on the available activation energy. This is usually determined by igniting the mixture with an electric spark. The explosive range is bounded by the lower explosive limit and the upper explosive limit. This means that below and above these limits, explosions will not happen. This fact can be utilised by sufficiently diluting the flammable substances with air or by preventing the ingress of air/oxygen into parts of the equipment. The latter option is, however, not or only with restrictions possible in environments where people regularly work and must therefore be reserved for technological equipment.
With technical equipment a large number of ignition sources is possible. In the following overview the numbers given behind the ignition sources refer to the appropriate sections of the basic standard: EN 1127-1: 1997 "Explosive atmospheres - Explosion prevention and protection- Part 1: Basic concepts and methodology."
Hot surfaces (5.3.2) arise as a result of energy losses from systems, equipment and components during normal operation. In the case of heaters they are desired. These temperatures can usually be controlled. In the event of a malfunction - for example with overloading or tight bearings - the energy loss, and therefore the temperature, increases unavoidably. Technical equipment must always be assessed as to whether it is stabilising - i.e. whether it can attain a final temperature, or whether non-permissible temperature increases are possible which need to be prevented by taking appropriate measures. Examples: coils, resistors or lamps, hot equipment surfaces, brakes or overheating bearings
Flames and hot gases (including hot particles ) (5.3.3) can occur inside combustion engines or analysis devices during normal operation and when a fault has occurred. Protective measures are required here which are able to permanently prevent them from leaving the enclosure. Examples: exhausts from internal combustion engines or particles which are formed by the switching sparks of power switches eroding material from the switch contacts
Mechanically generated sparks (5.3.4) are produced for example by grinding and cutting devices during normal operation and are therefore not permitted in a potentially explosive atmosphere. Cracks in rotating parts, parts sliding over each other without sufficient lubrication and similar situations can generate such sparks when malfunctioning and this must be carefully considered with respect to faults. The setting of special requirements for the materials used to make enclosures serves to reduce the risks from such ignition sources. Examples: tools such as a rusty hammer and chisel in contact with light alloys or the metal fork of a fork lift truck
Electrical apparatus (5.3.5) must normally be regarded as a sufficient ignition source. Only very low energy sparks with energies of only microwatt seconds may be regarded as too weak to start an explosion. For this reason, suitable measures must be adopted to prevent these ignition sources. Examples: switching sparks, sparks at collectors or slip rings
Electric rails and other earthed voltage supplies e.g. for electric corrosion protection of equipment, can result in stray electric currents, cathodic corrosion protection (5.3.6) which then may result in a potential difference between different earthing points. This is why a highly conductive connection to all the electrically conductive parts of the equipment must be provided so that the potential difference is reduced to a safe level. It is not relevant whether the conductive equipment is electrical or non-electrical parts of the installation, as the cause of the current may be found outside of the equipment. An equipotential bonding must always be provided, irrespective of whether or not such currents are expected or whether its sources are known.
Independently of whether or not there is an electrical voltage supply, electrical sparks can be caused by static electricity (5.3.7). The stored energy can be released in the form of sparks and function as an ignition source. Because this ignition source can arise quite independently of an electrical voltage supply, it must also be considered with non-electrical devices and components. It is connected with separation processes; therefore these cases must be assessed where this ignition source needs to be taken into account. Friction during normal operation can be the cause of electrostatic charging. For example, portable devices cannot - due to their portability - be earthed or connected to an equipotential bonding ring. When interacting with the clothes of the user, static charging can occur during normal operation. Static electricity must be prevented from becoming an ignition source by taking appropriate measures. Examples: Transmission belts made from plastic materials, enclosures of portable devices, synthetic clothing material. Separation processes when rolling out paper or plastic film, plastic pipe systems
Lightning (5.3.8) and the impact of lightning can result in the ignition of an explosive atmosphere. Lightning always results in the ignition of an explosive atmosphere. However, there is also a possibility of ignition due to the high temperature reached by lightning. Large currents flowing from where lightning strikes can produce sparks in the vicinity of the point of impact.
Radio frequency (RF) electromagnetic waves from 104 hz to 3 x 1011 Hz Among the ignition sources where radiation energy enters the explosive mixture, the following deserve to be mentioned: Electro-magnetic radiation - radio waves (5.3.9), Electro-magnetic radiation - IR radiation, visible light (5.3.10), ionising radiation - UV radiation (5.3.11), Ultrasonic (5.3.12). Systems, devices and components that use radiation may be set up and operated in the Ex area if their parameters are limited permanently and reliably and this equipment is checked. Examples: transmitting and receiving equipment, mobile telephones, photoelectric barriers and scanners
Finally, adiabatic compression and shock waves (5.3.13) inside tube-shaped structures operated at negative pressure can also become a source of ignition. Examples: breakage of a long fluorescent tube in a hydrogen/air atmosphere
88 5.5 50
Designed to design standards IEC/EN 60079-0 ff (gas and dust)
Approval by a notified body EC type examination certificate
Quality assurance system of the manufacturer in conformity with Directive 94/9/EC
Manufacturer Routine tests
Installation in conformity with the standards IEC/EN 60079-14 (gas) IEC/EN 61241-14 (dust)
Commissioning in conformity with the Directive 1999/92/EC
Maintenance and repair in conformity with the Directive 1999/92/EC IEC/EN 60079-17 (gas) IEC/EN 61241-17 (dust) IEC/EN 60079-19 (gas and dust)
Protection principles are defined to exclude equipment and components as ignition sources. Ignition sources which are caused by sparks from friction or impact or from electro-static charging have to be prevented in explosion protected equipment by selecting appropriate materials and by constructive measures, and this must be verified and confirmed by the appropriate tests. Four protection principles can prevent equipment from becoming an ignition source. The types of protection listed as examples in the overview are discussed in a different chapter. An important precondition for all the protection principles is that parts which are in unhindered contact with the explosive atmosphere must not be able to reach non-permitted temperatures with respect to the ignition temperature of substances present in the site of installation. This means that the ignition temperature is relevant for all protection principles. The protection principles can be equally applied to electrical and non-electrical devices and for gases and for dusts. The principles allow for a design in various safety categories in accordance with the Directive 94/9/EC or the Equipment Protection Level (EPL) according with EN 60079-0 ff: Category 1 - with very high level of protection and thus a very high degree of safety Category 2 - with high level of protection and therefore a high degree of safety Category 3 - with normal level of protection and therefore a conventional degree of safety EPL a with very high level of protection and thus a very high degree of safety EPL b with high level of protection and therefore a high degree of safety EPL c with normal level of protection and therefore a conventional degree of safety
Protection principles 1. Explosive mixtures can penetrate the item of equipment and be ignited. Measures are taken to ensure that the explosion cannot spread to the surrounding atmosphere. 2. The item of equipment is provided with an enclosure that prevents the ingress of an explosive mixture and/or contact with sources of ignition arising from the normal.
Flammable substances Gases
(EPL) Equipment Protection Level b b c b/c a/b/c b c c c c a/b/c b c a/b/c -
Flammeproof enclosures Powder filling Enclosed-break device
2 2 3 2/3 1/2/3 2 2 3 3 3 3 1/2/3 2 3 2 1/2/3 2
Gases and dust Gases
Pressurized enclosures Encapsulation Oil immersion Liquid immersion Restricted breathing Non-incendive component Hermetically sealed device Sealed device
Dust 3. Explosive mixtures can penetrate the enclosure but can not be ignited. Sparks and temperatures capable of causing ignition must be prevented.. 4. Explosive mixtures can penetrate the enclosure but can not be ignited. Sparks and temperatures able to cause ignition may only occur within certain limits. Gases
Protection by enclosure Increased safety Non-sparking device Protection by constructional safety
Intrinsically safe Protection by control of ignition sources
BARTEC applies these protection principles to its different pieces of equipment according to the application for which they are going to be used. 11
The requisite preconditions for the safe operation of electrical equipment in potentially explosive atmospheres are created in a joint effort by the manufacturers of explosion protected equipment and the constructors and operators of industrial plants. It is important that the operator of such plants should ensure that their personnel know how the danger of explosions is likely to arise and the measures that are to be taken to prevent it. The employees should be regularly trained on the contents of the explosion protection document in accordance with the Directive 1999/92/EC (occupational safety regulations) and informed by means of written corporate regulations which should be regularly updated.
Design regulations for explosion protected systems, equipment and components
Hazards arising from the handling of flammable gases, vapours and dusts are caused by uniform chemical and physical processes. For this reason, the protection against these hazards must be carried out in a uniform manner. Nearly universal uniform requirements have now been formulated by the International Electrotechnical Commission IEC, by the European Standardisation Committees CENELEC and CEN. Manufacturers and operators are required to adhere to these, and where there are increased protection requirements, they are monitored by notified bodies and the authorities.
An overview of the regulations for the determination of the parameters, the classification of zones, the design regulations for systems, devices and components as well as installation and operation in the area where explosive gases, vapours and dusts are present, is shown in the table below which corresponds to the version as of April 2010 and may be subject to subsequent changes.
Registration no. IEC Date of issue
Registration no. CEN/CENELEC Date of issue
Registration no. DIN Date of issue
Explosion protection basic concepts and safety parameters General Explosive atmospheres - Explosion prevention and protection Part 1: Basic concepts and methodology Explosive atmospheres - Explosion prevention and protection Part 2: Basic concepts and methodology for mining Potentially explosive atmospheres - Terms and definitions for equipment and protective systems intended for use in potentially explosive atmospheres Safety parameters of combustible gas and vapours Determination of the maximum explosion pressure and the maximum pressure rise of gases and vapours Part 1: Determination of the maximum explosion pressure EN 13673-1:2003-04-00 DIN EN 13673-1:2003-09-00 prEN 1127-1:2009-03-00 EN 1127-1:2007-11-00 EN 1127-2:2002 + A1:2008 EN 13237:2003-11-00 DIN EN 1127-1:2009-04-00 DIN EN 1127-1:2008-02-00 DIN EN 1127-2:2008-08-00 DIN EN 13237:2003-11-00
Determination of the maximum explosion pressure and the maximum rate of pressure rise of gases and vapours Part 2: Determination of the maximum rate of explosion pressure rise
EN 13673-2:2005-09-00
DIN EN 13673-2 Corrigendum 1:2007-08-00 DIN EN 13673-2:2005-12-00
Explosive atmospheres Part 20-1: Material characteristics - Gas and vapour classification, test methods and data
Follow-up document for: IEC 60079-1-1:2002-07-00; IEC/TR 60079-12:1978-00-00; IEC 60079-4:1975-00-00
IEC 60079-20-1:2010-01-00
FprEN 60079-20-1:2009-10-00
DIN IEC 60079-20-1:2008-04-00
Electrical apparatus for explosive gas atmospheres Part 20: Non-metallic parts of flameproof enclosures Testing of mineral oil hydrocarbons Determination of the ignition temperature Determination of the auto ignition temperature of gases and vapours Safety parameters of combustible dusts Explosive atmospheres Part 20-2: Material characteristics Combustible dusts test methods Electrical apparatus for use in the presence of combustible dust Part 2: Test methods; section 1: Methods for determining the minimum ignition temperatures of dust Electrical apparatus for use in the presence of combustible dust Part 2-1: Test methods; Methods for determining the minimum temperatures of dust
prEN 60079-20:1993-01-00
EN 14522:2005-09-00
DIN 51794:2003-05-00 -
IEC 31J/157/CD:2008
DIN IEC 60079-20-2:2009-01-00
IEC 61241-2-1:1994-12-00
EN 50281-2-1:1998-09-00
DIN EN 50281-2-1:1999-11-00
Explosion protection basic concepts and safety parameters Safety parameters of combustible dusts Electrical apparatus for use in the presence of combustible dust Part 2: Test methods - section 2: Methods for determining the electrical resistivity of dust in layers Electrical apparatus for use in the presence of combustible dust Part 2: Test methods - section 3: Method for determining minimum ignition energy of dust/air mixtures Electrical apparatus for use in the presence of combustible dust Part 2: Test methods - section 4: Method for determining the minimum explosible concentration of dust/air mixtures IEC/TR 61241-2-2 Corrigendum 1:1994-05-00 IEC/TR 61241-2-2:1993-08-00 EN 61241-2-2:1995-08-00 DIN EN 61241-2-2:1996-04-00
IEC 61241-2-3:1994-09-00
prEN 61241-2-4:1993-05-00
Explosion protection for equipment (protection methods) Protection methods for electrical apparatus - combustible gas, vapours and dust Explosive atmospheres Part 0: Equipment - General requirements Electrical apparatus for use in the prescence of combustible dust Part 0: General requirements Explosive atmospheres Part 33: Equipment protection by special protection "s" Caplights for use in mines susceptible to firedamp Part 1: General requirements Construction and testing in relation to the risk of explosion Caplights for use in mines susceptible to firedamp Part 2: Performance and other safety-related matters IEC 60079-0:2007-10-00 IEC 61241-0 Corrigendum 1:2005-11-00 IEC 61241-0:2004-07-00 IEC 31/847/CD:2009-11-00 EN 60079-0:2009-08-00 DIN EN 60079-0:2010-03-00 -
DIN IEC 60079-33:2009-10-00
FprEN 60079-35-1:2009-12-00
DIN IEC 60079-35-1:2009-03-00
DIN IEC 60079-35-2:2010-02-00
Protection methods for electrical apparatus - combustible gas and vapours Explosive atmospheres IEC 60079-1 Part 1: Equipment protection by flameproof enclosures "d" Corrigendum 1:2008-09-00 IEC 60079-1:2007-04-00 Explosive atmospheres Part 2: Equipment protection by pressurized enclosure "p" Explosive atmospheres Part 5: Equipment protection by powder filling "q" Explosive atmospheres Part 6: Equipment protection by oil immersion "o" Explosive atmospheres Part 7: Equipment protection by increased safety "e" IEC 60079-11 Corrigendum 1:2006-12-00 IEC 31/794/CDV:2009-02-00 IEC/TR 60079-13:1982-00-00 IEC 60079-15:2007-11-00 FprEN 60079-11:2009-10-00 EN 60079-11:2007-01-00 FprEN 60079-13:2009-02-00 DIN IEC 60079-11 DIN EN 60079-11:2007-08-00 DIN IEC 60079-13:2007-11-00 Explosive atmospheres Part 11: Equipment protection by intrinsic safety "i" Explosive atmospheres Part 13: Equipment protection by pressurized room "p" Electrical apparatus for explosive gas atmospheres Part 15: Construction, test and marking of type of protection "n"electrical apparatus IEC 60079-2:2007-02-00 IEC 60079-5:2007-03-00 IEC 60079-6:2007-03-00 IEC 60079-7:2006-07-00 EN 60079-1:2007-07-00 DIN EN 60079-1:2008-04-00
EN 60079-2:2007-11-00 EN 60079-5:2007-11-00 EN 60079-6:2007-05-00 EN 60079-7:2007-01-00
DIN EN 60079-2:2008-07-00 DIN EN 60079-5:2008-07-00 DIN EN 60079-6:2008-02-00 DIN EN 60079-7:2007-08-00
FprEN 60079-15:2009-10-00 EN 60079-15:2005-10-00
DIN IEC 60079-15:2007-11-00 DIN EN 60079-15:2006-05-00
Explosion protection for equipment (protection methods) Protection methods for electrical apparatus - combustible gas and vapours Electrical apparatus for explosive gas atmospheres Part 16: Artificial ventilation for the protection of analyzer(s) houses Explosive atmospheres Part 18: Equipment protection by encapsulation "m" Electrical apparatus for explosive gas atmospheres Part 25: Intrinsically safe systems IEC/TR 60079-16:1990-04-00 -
IEC 60079-18 Corrigendum 1:2009-06-00 IEC 60079-18:2009-05-00 IEC 31G/202/FDIS:2009-11-00 IEC 60079-25:2003-08-00
EN 60079-18:2009-12-00
DIN EN 60079-18:2007-09-00 DIN EN 60079-18 Corrigendum 1:2006-09-00 DIN EN 60079-18:2005-01-00 DIN IEC 60079-25:2007-08-00 DIN EN 60079-25 Corrigendum 1:2006-09-00 DIN EN 60079-25:2004-09-00 DIN EN 60079-26 Corrigendum 1:2009-12-00 DIN EN 60079-27:2008-12-00
FprEN 60079-25:2009-11-00 EN 60079-25:2004-01-00
Explosive atmospheres Part 26: Equipment with equipment protection level (EPL) Ga Explosive atmospheres Part 27: Fieldbus intrinsically safe concept (FISCO) Explosive atmospheres Part 28: Protection of equipment and transmission systems using optical radiation Explosive atmospheres Part 29-1: Gas detectors Performance requirements of detectors for flammable gases Explosive atmospheres Part 29-2: Gas detectors - Selection, installation, use and maintenance of detectors for flammable gases and oxygen Explosive atmospheres Part 29-4: Gas detectors - Open path apparatus General requirements and test methods Explosive atmospheres Part 30-1: Electrical resistance trace heating General and testing requirements Explosive atmospheres Part 30-2: Electrical resistance trace heating Application guide for design, installation and maintenance
IEC 60079-26 Corrigendum 1:2009-03-00 IEC 60079-26:2006-08-00 IEC 60079-27:2008-01-00
EN 60079-26:2007-03-00 DIN EN 60079-26:2007-10-00 EN 60079-27:2008-05-00
IEC 60079-28:2006-08-00
EN 60079-28:2007-03-00
DIN EN 60079-28:2007-10-00
IEC 60079-29-1:2007-08-00
EN 60079-29-1:2007-11-00
DIN EN 60079-29-1:2008-07-00
IEC 60079-29-2:2007-08-00
EN 60079-29-2:2007-11-00
DIN EN 60079-29-2:2008-07-00
IEC 60079-29-4:2009-11-00
FprEN 60079-29-4:2009-08-0
DIN IEC 60079-29-4:2007-07-00
IEC 60079-30-1:2007-01-00
EN 60079-30-1:2007-04-00
DIN EN 60079-30-1:2007-12-00
IEC 60079-30-2:2007-01-00
EN 60079-30-2:2007-04-00
DIN EN 60079-30-2:2007-12-00
Protection methods for electrical apparatus - combustible dust Electrical apparatus for use in the presence of combustible dust Part 1: Protection by enclosures "tD" Explosive atmospheres Part 31: Equipment Protection by enclosures "tD" Electrical apparatus for use in the presence of combustible dust Part 4: Type of protection "pD" Electrical apparatus for use in the presence of combustible dust Part 11: Protection by intrinsic safety "iD" Electrical apparatus for use in the presence of combustible dust Part 18: Protection by encapsulation "mD" IEC 61241-1:2004 EN 61241-1:2004 DIN EN 61241-1 Corrigendum 1:2007-07-00 DIN EN 61241-1:2005-06-00 DIN IEC 60079-31:2006-09-00
IEC 60079-31 Corrigendum 1:2009-03-00 IEC 60079-31:2008-11-00 IEC 61241-4:2001-03-00
EN 60079-31:2009-12-00
EN 61241-4:2006-12-00
DIN EN 61241-4:2007-07-00
IEC 61241-11 Corrigendum 1:2006-02-00 IEC 61241-11:2005-10-00 IEC 61241-18:2004
EN 61241-11:2006-12-00
DIN EN 61241-11:2007-07-00
DIN EN 61241-18:2005-07-00
Explosion protection in equipment (types of protection) Protection methods for non-electrical equipment - combustible gas, vapours and dust Non-electrical equipment for use in potentially explosive atmospheres Part 1: Basic method and requirements Non-electrical equipment for use in potentially explosive atmospheres Part 2: Protection by flow restricting enclosure fr Non-electrical equipment for use in potentially explosive atmospheres Part 3: Protection by flameproof enclosure d Non-electrical equipment intended for use in potentially explosive atmospheres Part 5: Protection by constructional safety c Non-electrical equipment for use in potentially explosive atmospheres Part 6: Protection by control of ignition source b Non-electrical equipment for potentially explosive atmospheres Part 8: Protection by liquid immersion k Manufacturing & quality system Explosive atmospheres Part 34: Application of quality systems for equipment manufacture Explosion protection in plants Classification of Ex areas with combustible gas, vapour and dust Explosive atmospheres Part 10-1: Classification of areas Explosive gas atmospheres Explosive atmospheres Part 10-2: Classification of areas Combustible dust atmospheres IEC 60079-10-1:2008-12-00 EN 60079-10-1:2009-03-00 DIN EN 60079-10-1:2009-10-00 prEN ISO/IEC 80079-34: 2009-11-00 EC 31M/31/CDV:2009-11-00 DIN EN ISO/IEC 80079-34: 2010-02-00 EN 13463-1:2009-01-00 DIN EN 13463-1:2009-07-00
EN 13463-2:2004-11-00
DIN EN 13463-2:2005-02-00
EN 13463-3:2005-04-00
DIN EN 13463-3:2005-07-00
prEN 13463-5:2009-03-00
DIN EN 13463-5:2009-04-00
EN 13463-6:2005-04-00
DIN EN 13463-6:2005-07-00
EN 13463-8:2003-09-00 DIN EN 13463-5:2003-12-00
DIN EN 13463-8:2004-01-00 DIN EN 13463-5:2004-03-00
IEC 60079-10-2:2009-04-00
EN 60079-10-2:2009-09-00
DIN EN 60079-10-2:2010-03-00
Installation, maintenance and repair of electrical equipment Explosive atmospheres Part 14: Electrical installations design, selection and erection Electrical apparatus for use in the presence of combustible dust Part 14: Selection and installation Explosive atmospheres Part 17: Electrical installations inspection and maintenance Electrical apparatus for use in the presence of combustible dust Part 17: Inspection and maintenance of electrical installations in hazardous areas (other than mines) Explosive atmospheres Part 19: Equipment repair, overhaul and reclamation IEC 60079-14:2007-12-00 EN 60079-14:2008-10-00 DIN EN 60079-14:2009-05-00
IEC 61241-14:2004-07-00
EN 61241-14:2004-09-00
DIN EN 61241-14:2005-06-00
IEC 60079-17:2007-08-00
EN 60079-17:2007-09-00
DIN EN 60079-17:2008-05-00 DIN EN 60079-17 Corrigendum 1:2008-10-00 -
EN 61241-17:2005-05-00
IEC 31J/172/CDV:2009-11-00 IEC 60079-19:2009-04-00
FprEN 60079-19:2009-11-00 EN 60079-19:2007-07-00
DIN IEC 60079-19:2009-04-00 DIN EN 60079-19 Corrigendum 1:2008-08-00 DIN EN 60079-19:2008-02-00
Note about how to use the table The information is based on the IEC titles, in cases where there is no IEC document available, the EN titles have been used. The format of the date has been standardised. It refers to the state on 2010-04-30 which was accessible to the author. This style seems to be becoming universally accepted, but has not been introduced in all the documents. The table is to provide an information overview of the standard. For concrete work with the standards and their procurement, the latest update should be requested from the publisher or from the standardisation committee.
With the help of this table, the contents listed in the title/contents column can be correlated to the regional and national equivalents. The regional and national title does not need to correspond to the "world" title. At BARTEC the design regulations are consistently applied for electrical equipment. Conformity is - after the completion of the development at BARTEC - checked by notified bodies, test laboratories of the IEC Ex-scheme as well as test laboratories of the European Community or by national test laboratories, and compliance is monitored and realised using a quality assurance system for every piece of equipment produced. During the routine test, safety-relevant requirements are checked according to the specifications and confirmed by means of a marking. BARTEC also supports its customers with non-electrical equipment using the knowledge it has accumulated over decades of experience.
Relevance and advantage of the area classification
The practice has been established of dividing potentially explosive atmospheres into zones. This classification takes the different dangers from explosive atmospheres into account and allows explosion protection measures to be taken which reflect the situation both from the point of view of safety engineering and of economic efficiency. For the European community, the zone definitions are uniformly provided in Directive 1999/92/EC. It must be applied with technical understanding of the specific situation. IEC 60079-10-1 assumes an approximately similar classification for gases and vapours which will also apply to future facilities constructed in accordance with the US standard NEC 505. IEC 60079-10-2 provides support for the zone classification with dusts. Potentially explosive atmospheres are classified depending on the frequency and duration of the explosive atmosphere. This classification provides the scope of the measures to be taken according to Annex II section A in the Directive 1999/92/EC in conjunction with Annex I of the Directive 94/9/EC.
Bag filling point (dust) Filling station (gases and vapours)
Source: Firm of AZO, Osterburken
Zone 0 Zone 1 Zone 2 place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is present continuously or for long periods or frequently place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently area in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur, occasionally in normal operation area in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only
Notes: 1. Layers, deposits and heaps of combustible must be considered as any other source which can form an explosive atmosphere. 2. 'Normal operation' means the situation when installations are used within their design parameters. 3. The definitions comply with the EC Directive. In the HSE occupational safety regulations, hazardous explosive atmospheres are defined. In according with EN 1127-1 Section 3.17 defines potentially explosive atmospheres as follows: Mixture of air and flammable gases, vapours, fogs and dusts under atmospheric conditions due to a transmission of the burning process to the entire unburned mixture after inflammation. Section 3.19 defines hazardous potentially explosive atmospheres as follows: Potentially explosive atmosphere which will lead to damage in case of explosion.
In places of work the potentially explosive atmospheres are normally classified at most as Zone 1 and 2 and/or 21 and 22. Zones 0 and 20 are restricted to very small inaccessible areas in work places or are usually restricted to the inside of technical equipment.
Silo (dust)
Pump house (gases and vapours)
In order to allow a combination of measures for explosion protection, which is optimised with respect to the chemical-physical properties of the flammable gases, vapours or dusts, to be made, and therefore a standardisation of the types of protection to be possible for the manufacturer, a system of explosion parameters has been created. These are determined using an application-orientated test method. Before flammable substances can react with the atmospheric oxygen in an explosion, energy must be provided. This energy may, for example, be exchanged on a surface. A heated surface increases the energy content of the explosive mixture in contact with it. If the surface temperature is sufficiently high, this increased energy content can lead to the explosive reaction. However, the energy may also be supplied through a spark or a hot gas jet flowing out of a gap into the explosive mixture. Both types lead to different explosion parameters being defined.
GASES/VAPORS temperature class
Many factors such as size, shape, type and surface quality have an influence on the ignition temperature. IEC, CENELEC and other standardisation committees have agreed on a method for gases and vapours defined in IEC 60079-20-1 "Method of test ignition temperature". This method is defined in such a way, that a value very close to the lowest practically possible, is determined. By means of this method, gases and vapours are divided into temperature classes. According to these temperature classes, the surface temperatures in explosion protected equipment and other technological objects is designed in such a way that ignition by the surface is not possible. In the standard, permissible excess values and necessary safety margins below these standard values are defined in detail.
Ignition temperature range of the mixture
> 450 C > 300 ... < 450 C > 200 ... < 300 C > 135 ... < 200 C > 100 ... < 135 C > 85 ... < 100 C
450 C 300 C 200 C 135 C 100 C 85 C
For different types of dust, the method for determining the ignition temperature has also been unified and coded in document IEC 61241-2-1. Please note that dust in its deposited form (layer) has a different ignition temperature than in its stirred form (cloud). The permissible surface temperature for those parts of the systems, equipment and components accessible to the dust is determined by subtracting 75 K (Tperm L = Tmin L - 75 K) from the value determined for the dust layer and by multiplying by 2/3 (Tperm C = 2/3Tmin C) the value determined for the dust cloud. The smaller of the 2 values determined in this way corresponds to the lowest permissible surface temperature of the equipment (Tperm L > Tperm < Tperm C). The surface is the area accessible to the dust, temperature classes are not defined for dust, so that a concrete type of dust must always be assumed. The parameters are made available in comprehensive tables, laboratories determine the values on request, and a small, non-official overview is contained in the following table (page 22).
Ignition temperature/Dusts Permissible temperature from layer Tperm L = Tmin L - 75 K Permissible temperature from cloud Tperm L = 2/3 Tmin C
Max. permissible surface temperature of the equipment Tperm L > Tperm < Tperm C
Layers of dust exceeding 5 mm
If deposits of dust with thicknesses of more than 5 mm to 50 mm can accumulate on devices, the maximum permissible surface temperature must be reduced accordingly. The diagram from the installation standard (EN 60079-14) can be used as an aid here. Accordingly, where dust has an ignition temperature (smouldering temperature where the layer is 5 mm thick) of more than 250 C, the maximum surface temperature must be adjusted to suit the characteristics. Where types of dust have an ignition temperature (smouldering temperature for 5 mm layer thickness) less than 250 C or where there is a doubt about the characteristic curve, the dependence must be determined in laboratory tests.
Max. permissible surface temperature of the equipment
Smouldering temperature where layer thickness is 5 mm. 400 C < T5 mm 320 C < T5 mm < 400 C 250 C < T5 mm < 320 C
400 C 300
50 mm 40 Layer thickness
Examples of the ignition temperatures of different types of dust
Designation of the solid material
A values ignition temperature IEC 61241-2-1 deposit (C)
B values ignition temperature IEC 61241-2-1 cloud (C)
Permissible limiting temperature lowest value of the calculation (A-75K) and 2/3*B 450... > 300 300... 280... > 280 > 260 260... 230... > 230 > 215 215... 200... > 200 > 180 180... 165... > 165 > 160 160... > 135
Dust from natural materials (examples) Cotton Brown coal Cellulose Cereals Wood resin Sawdust (wood) Cocoa Copra Cork Fodder concentrate Linen Milk powder Paper Pectin sugar Soya Starch Hard coal Tobacco Tapioca Tea Peat Wheat flour Sugar beet 350 225 370 290 290 300 460 290 300 295 230 340 300 380 245 290 245 300 290 300 295 450 290 560 380 500 420 500 400 580 470 470 525 440 440 540 410 500 440 590 450 450 510 360 480 460 275 150 295 215 215 225 385 215 225 220 155 265 225 273 170 215 170 225 215 225 220 320 215
Dust of chemical technical products (examples) Cellulose ether Isosorbide dinitrate Unvulcanised rubber Petroleum coke Polysaccharide deriv. Polyvinyl acetate Polyvinyl chloride Soot Laminated plastic Sulphur Metal dusts (examples) Aluminium Bronze Iron Copper silicon alloy Magnesium Manganese Zinc 22 280 260 300 305 410 285 440 530 390 310 690 610 330 570 205 185 206 230 335 210 365
240 220 280 270 340 380 385 330 280
220 460 690 580 500 530 620 510 280
146 145 205 195 265 305 310 255 186
Explosion sub-group
Minimum ignition current ratio (MIC), Maximum experimental safe gap (MESG) - GASES/VAPORS
Ignition on a hot surface occurs in a relatively large macroscopic part of the mixture. In contrast, the ignition from a spark spreads in a relatively small microscopic part of the volume. The discharge from a capacitor or the interruption of a predefined resistive/inductive electric circuit can be used for classifying gases and vapours or dusts according to their ease of ignition in the microscopic part of the mixture volume. For the assessment of the ignition of gases and vapours in a circuit using a equipment defined in IEC 60079-11, a comparative value with methane as reference in a standardised circuit is used. This comparative value is the minimum ignition current ratio, MIC. It is the means used for classifying gases and vapours within explosion group II in the subgroups IIA, IIB and IIC. An analogous grading is done when the ignitability of a hot gas jet escaping from a gap is used for the classification. In IEC 60079-20-1 Method of test for ascertainment of the experimental safe gap, a test apparatus is agreed in which a spherical gas volume of 20 cm is formed by two hemispheres. These have a 25 mm wide flange. This ball-shaped object is placed into a larger vessel and both spaces are filled with the mixture for which the safe gap is to be determined. The gap between the 25 mm wide flanges for which ten ignitions inside the ball volume just fail to ignite the mixture in the outer vessel is a value specific to the mixture and is called the maximum experimental safe gap, MESG. The processes involved in the prevention or spread of the explosion in the gap are very complex. Classifying the gases and vapours by the safe gap results approximately - with a small overlap - in the same classification as that obtained with the minimum ignition current ratio. IEC/TR 60079-20-1 provides an overview of the classification using the two measuring methods MESG and MIC. The safe gap value is of considerable importance for designs of protection type Flameproof enclosure; the value for the minimum ignition current ratio is important for those of protection type Intrinsic safety. For these two types of protection, the subgroups IIA, IIB and IIC for gases and vapours are relevant. The information on gases and vapours can also be applied approximately to mists. For the assessment of conditions concerning electrostatic discharge, the minimum ignition energy of gases and vapours from the assignment to sub-group IIA, IIB or IIC can be assumed: IIA approx. 300 Ws IIB approx. 150 Ws IIC < 50 Ws The minimum ignition energy, a parameter similar to the minimum ignition current, is determined in accordance with IEC 61241-2-3 for flammable dusts. Conductivity of the dust The IEC 61241-2-2 contains the test method for determining the specific electrical resistance of dust. The various types of dust are divided into 3 sub-groups according to this resistance:
combustible flyings non-conductive combustible dust, specific electrical resistance > 10 conductive combustible dust, specific electrical resistance < 10
The following table shows examples of the assignment of gases and vapours to the respective temperature classes and explosion sub-groups:
Subdivision of gases and vapours
Gases and vapours Assignment of the gases and vapours according to Ignition temperature Town gas Hydrogen > 450 C Temperature class Maximum surface temperature of the equipment Permissible temperature classes of the equipment
Acetone Ammonia Benzene - pure Acetic acid Ethane Ethyl acetate Ethyl chloride Carbon monoxide Methane Methanol Methylene chloride Naphthalene Phenol Propane Toluene Ethyl alcohol i amyl acetate n butane n butyl alcohol Cyclohexane Acetic anhydride
Ethylene, Ethylene oxide
Ethine (acetylene)
> 300 C up to < 450 C
Petroleum spirit - gen. Ethylene glycol Diesel fuel Hydrogen sulphide, Jet propulsion fuel Heating fuel DIN 51603 n hexane Acetaldehyde Ethyl ether
> 200 C up to < 300 C
> 135 C up to < 200 C > 100 C up to < 135 C Carbon bisulphide > 85 C up to < 100 C
only T6
Explosion groups (Marking)
Permissible equipment groups IIA, IIB or IIC IIB or IIC only IIC
It applies to all types of protection where parts that are in unhindered contact with the explosive atmosphere are not permitted to reach unacceptably high temperatures. Taking into account both the environmental temperature and the heating effect, the temperature may attain maximum values which corresponds to the temperature class or the permissible surface temperature specified for flammable dusts in accordance with which the explosive atmosphere has been classified.
All generally applicable requirements for the equipment are summarised in the standards IEC 60079-0 for electrical equipment and components (gases, vapours and dusts) EN 13463-1 for non-electrical equipment and components. The ignition protection standards can complement or nullify these requirements. Uniform protection requirements concerning several types of protection such as protection against electrostatic charging, provision of a potential bond for metal enclosures, or mechanical strength against impact, are summarised in these standards under general engineering requirements. In this case, individual, more specific standards can demand either more stringent requirements or less stringent ones. These requirements are based partially on those for electrical equipment for gases and vapours, deviations for dust and non-electrical equipment are contained in the individual basic standards. Categories 1 to 3 which the equipment has to fulfil can also include different general requirements. The general temperature range for the application of explosion protected electrical equipment is defined as -20 C to +40 C. Permissible deviations extending or restricting the temperature range must be specified. The parameters determined at approximately +20 C in the laboratory for the subgroups IIA, IIB and IIC apply for a temperature range of 40 K - that is to say also from -20 C to +60 C. These two temperature ranges take, on the one hand, the situation at the workplace into account and also, on the other, a certain heating up of the equipment during operation. The explosion pressure, permissible gap widths and permissible non-igniting currents change outside this temperature range. This has to be considered when using the equipment, and it can require different test conditions.
Gases/Vapours Type of protection
Flameproof enclosures Enclosed-break device Non-incendive component Pressurized enclosures Powder filling Oil/Liquid immersion Increased safety Non-sparking device Protection by constructional safety Encapsulation Hermetically sealed device Encapsulated device Sealed device Protection by enclosure Intrinsically safe Energy limitation Protection by control of ignition sources Restricted breathing
Gases/Vapours non-electrical equipment
Dusts electrical equipment
Marking Ex d Gb II 2 G in accordance with IEC 60079-0 Marking d II 2 G in accordance with EN 13463-1 Principle
A type of protection in which the parts which could ignite an explosive atmosphere are located inside an enclosure which can withstand the pressure of an explosion of the explosive mixture inside, and prevents the transmission of the explosion to the explosive atmosphere surrounding the enclosure. Technically unavoidable gaps are so long and narrow that hot gases jetting out will have lost their power to cause ignition by the time they reach the outside of the enclosure, or, alternatively, if the gaps are only required for the manufacturing process they might be sealed with adhesive.
Mechanical strength in accordance with a defined safety factor to withstand internal explosion pressure. As an orientation value, it may be assumed that inside the sphere approx. 0.8 MPa (8 bar) can be generated and that this sphere used as an Ex d enclosure must be able to withstand a pressure of 1.2 MPa (12 bar). Any gap between two parts of the enclosure must be kept so narrow and long that hot gas flowing out will not be able to ignite any explosive atmosphere which may be present in the potentially explosive atmosphere. The parameters for the gaps preventing the transmission of the ignition, width/length, are different for the explosion subgroups IIA, IIB and IIC. The most stringent requirements with regard to the gap parameters apply to enclosures in explosion subgroup IIC.
Equipment where, during normal operation, sparks, electric arcs and/or hot surfaces are generated such as switchgear, slip rings, collectors, adjustable resistors, fuses or lamps, heating cartridges, friction brakes. 26
Marking Ex nC Gc II 3 G in accordance with IEC 60079-0 Principle
Switchgear as a variant of the Ex n type of protection, with contacts which close and open a circuit potentially able to trigger an explosion, where the enclosure will withstand an internal explosion of a mixture of subgroup IIA, IIB or IIC without being damaged and without transferring the explosion to the external mixture in the surrounding area.
Free internal volume 20 cm The encapsulation must permit a permanent temperature of 10 K compared to the maximum operating temperature Limited to AC 690 V and 16 A
Non-incendive component
Variant of the Ex n type of protection with contacts which close and open a circuit potentially able to trigger an explosion, where the contact mechanism or the enclosure into which the contacts are enclosed is designed in such a way that the ignition of a mixture of subgroup IIA, IIB or IIC in the surrounding environment is prevented as long as defined operating conditions apply.
Free internal volume 20 cm The encapsulation must permit a permanent temperature of 10 K compared to the maximum operating temperature The combination of the parts is tightly sealed The design of the contacts will extinguish any incipient flame Limited to AC 254 V and 16 A L and C are part of the test Explosion subgroups IIA, IIB and IIC are to be treated differently
Marking Ex p Gb II 2 G in accordance with IEC 60079-0 Marking Ex pD Db II 2 D in accordance with IEC 61241-0 Marking p II 2 G/D in accordance with EN 13463-1 Principle
The ingress of the surrounding atmosphere into the enclosure of electrical equipment is prevented by maintaining an ignition shield gas (air, inert or a different suitable gas) inside it at a pressure above atmospheric pressure. The overpressure is maintained with or without constant flushing of the protective gas.
Strength of the enclosure; the surrounding, flushed enclosure must withstand 1.5 times the overpressure experienced during normal operation. Flush before commissioning the electrical equipment. Shut-down or alarm if the flushing gas flow or overpressure fails.
Equipment where during normal operation sparks, electric arcs or hot surfaces are generated and complex industrial equipment (controls) which must be operated in a potentially explosive atmosphere protected by this type of protection. Large machines, slip ring or collector motors, switch cabinets and control cabinets and analytical apparatus.
Marking Ex pz Gc II 3 G in accordance with IEC 60079-0 Principle
Use of a protective gas preventing ignition inside an enclosure to prevent the formation of an explosive atmosphere inside the enclosure by maintaining a pressure greater than the that in the surrounding atmosphere.
The important difference from the pressurized enclosure is the restriction to an enclosure where no internal sources are available and no flammable gases or vapours can be released. Strength of the enclosure. Flush before commissioning the electrical equipment. Shut-down or alarm if the flushing gas flow or overpressure fails.
Equipment where during normal operation sparks, electric arcs or hot surfaces are generated and complex industrial equipment (controls) which must be operated in a potentially explosive atmosphere protected by this type of protection. Analytical apparatus without internal sources.
Marking Ex q Gb II 2 G in accordance with IEC 60079-0 Principle
By filling the enclosure with a finely grained powder, an arc within the enclosure is unable, with correct use, to ignite the explosive atmosphere outside. There must be no risk of ignition by flames, nor by increased temperatures at the surface of the enclosure.
The filling such as sand, glass balls etc. has to fulfil specific requirements, as must the design of the enclosure. The filling must not be able to leave the enclosure, neither during normal operation, nor as the result of electric arcs or other processes inside the powder-filled enclosure.
Capacitors, electronic assembly groups or transformers which are used in a potentially explosive atmosphere. Often components where sparks or hot surfaces occur but whose functioning is not affected by the finely grained filling.
Oil/ 2)Liquid immersion
Marking Ex o Gb II 2 G in accordance with IEC 60079-0 Marking k II 2 G in accordance with EN 13463-1
Parts which might ignite an explosive atmosphere are immersed in oil or other non-flammable, insulating liquid so that gases and vapours above the oil level and outside the enclosure cannot be ignited by electric arcs or sparks generated below the oil level, or by hot residual gases from the switching process or by hot surfaces - e. g. on a resistor.
Stipulated, insulating liquids, e. g. oil Protection of the liquid from contamination and moisture. Non-electrical equipment - Liquids - Wetted surfaces Assurance and possibility of monitoring that the oil level is safe - When heated up or cooled - For identification of leaks Restricted to non-portable equipment.
Large transformers, switchgear, starting resistors and complete starting controllers. Gear
Marking Ex e Gb II 2 G in accordance with IEC 60079-0 Principle
Additional measures provide a higher level of protection. This ensures reliable prevention of unacceptably high temperatures and sparks or electrical arcs, both on the internal and on the external parts of electrical equipment whose normal operation does not involve unacceptably high temperature sparks or arching.
For uninsulated, live parts, special protective requirements apply. Air and creepage gaps are made wider than is generally the case in industry. Special conditions apply to the IP protection degree to be adhered to. For windings, their design, mechanical strength and insulation, higher requirements apply and the windings must be protected from increased temperatures. Minimum cross sections are stipulated for winding wire, the impregnation and reinforcement of coils and for thermal monitoring equipment.
Marking Ex nA Gc II 3 G in accordance with IEC 60079-0 Principle
For uninsulated, live parts, special protective requirements apply. Air and creepage gaps are specified. Special requirements must be fulfilled by certain types of equipment.
Protection by constructional safety
Marking c II 2 G/D in accordance with EN 13463-1 Principle
The systems, equipment and components are constructed in a way which ensures that they cannot turn into an ignition source under normal operation or in cases of faults.
Requirements placed upon the enclosure material are applicable as with the other types of protection (refer to, e. g., EN 60079-0). The components must be selected in a way which ensures that their heating-up, e. g. by means of friction, is excluded. Furthermore, friction occurring under normal operation must not lead to electrostatic charging or friction sparks. The constructive requirements - derived from EN 1127-1 - must be verified with regard to possible ignition sources.
Presently, only little experience is available as the standard is only applicable as draft yet. 30
Marking Ex ma/mb/mc Ga/Gb/Gc II 1/2/3 G in accordance with IEC 60079-0 Marking Ex ma/mb/mc Da/Db/Dc II 1/2/3 D in accordance with IEC 61241-0 Principle
Parts that could ignite an explosive atmosphere by means of sparks or heat are potted so as to prevent ignition of the explosive atmosphere. This is achieved by encapsulating the components in a compound resistant to physical - especially electrical, thermal and mechanical - and chemical influences.
Encapsulation: - Breakdown strength - Low water absorption - Resistance to various influences - Casting compound must be of the stipulated thickness all round - Cavities are only permitted to a limited extent - As a rule the casting compound is only penetrated by the cable entries The load on the components is limited or reduced Increased clearance between live parts
Static coils in ballasts, solenoid valves or motors, relays and other control gear of limited power and complete PCBs with electronic circuits.
The equipment may include cavities. It is constructed in such a way that the external atmosphere cannot enter.
Sealed by means of a melting process e. g.: - Soft solder - Hard solder - Welding - Fusing of glass and metal
Spark generating equipment
The equipment may include cavities which are fully enclosed similar to the encapsulation type of protection e. g. in a casting compound, so that ingress of the outer atmosphere is prevented.
It must be impossible to open the equipment during normal operation, internal free volume 100 cm External connections, terminals or cables must be available Cast seal must permit permanent operating temperature 10 K compared to the maximum operating temperature It must not be possible for elastic seals to become mechanically damaged under normal operating conditions; they must maintain their sealing properties over the service life of the equipment
Contact systems, static coils in ballasts, solenoid valves or motors and complete PCBs with electronic circuits.
The equipment may include cavities, which are fully enclosed similar to the encapsulation type of protection so that ingress of the outer atmosphere is prevented.
It must be impossible to open the equipment during normal operation, internal free volume 100 cm External connections, terminals or cables must be available It must not be possible for elastic seals to become mechanically damaged under normal operating conditions; they must maintain their sealing properties over the service life of the equipment
Marking Ex ta/tb/tc Da/Db/Dc II 1/2/3 D in accordance with IEC 60079-0 Principle
Minimum degree of protection in accordance with IEC/EN 60529 IP 6X Consideration of dust accumulating on the surface and reduction of permissible surface temperature with dust layer 5 mm are possible
Various equipment where during normal operation sparks, electric arcs or hot surfaces occur and complex industrial designs (controllers) which by means of this type of protection can be utilised in the potentially explosive atmosphere. 32
Marking Ex ia/ib/ic Ga/Gb/Gc II 1/2/3 G in accordance with IEC 60079-0 Marking Ex ia/ib/ic Da/Db/Dc II 1/2/3 D in accordance with IEC 61241-0 Principle
Intrinsically safe electrical equipment contains only circuits that meet the requirements of intrinsically safe circuits. Intrinsically safe circuits are circuits in which no spark or thermal effect occurring under the test conditions laid down in the standard can ignite the explosive atmosphere of subgroups IIA, IIB and IIC or of an air/dust mixture. The test conditions cover normal operation and certain fault conditions stipulated in the standard.
Use of certain components for electrical and electronic circuits. Lower permitted load on the components than in ordinary industrial applications with regard to - voltage related to electric strength - current related to heat Voltage and current, including a safety margin, are kept permanently so low that no impermissible temperatures can occur, and, in the event of open circuit or short-circuit, sparks and electric arcs possess so little energy that they are unable to ignite an explosive atmosphere. An impression of this protection type is provided by the fact that explosive atmospheres of subgroup IIA require only a few hundred W and those of subgroup IIC only 10 W for ignition.
Measuring and monitoring instrumentation and control. Sensors working on the basis of physical, chemical or mechanical principles and at limited power. Actuators working on the basis of optical, acoustic and, to a certain extent, mechanical principles.
Marking Ex nL Gc II 3 G in accordance with IEC 60079-0 Principle
These are circuits in which no spark or thermal effect occurring under the test conditions laid down in the standard can ignite the explosive atmosphere of subgroups IIA, IIB and IIC or of an air/dust mixture. The test conditions cover normal operation and certain fault conditions stipulated in the standard. The permissible currents or voltages exceed those stipulated for the intrinsic safety type of protection.
The requirements to be fulfilled by the circuit and the loads on the components are lower than those for the intrinsic safety type of protection. Also with regard to errors, lower requirements apply.
Protection by control of ignition sources
Marking b II 2 G/D in accordance with EN 13463-1 Principle
By monitoring ignition sources during normal operation, which are not present but might develop, such as parts heating up, reaction in critical situations is possible. Currently there is the idea to draft such a standard.
Use of sensor/actuator devices to monitor various physical-technical variables (temperature, pressure, flow, speed, vibrations etc.) To limit the risk of ignition, an evaluation is done of the quality (function) of the ignition sources at the mechanical equipment and the corresponding sensor/actuator monitoring equipment . The functional reliability (minimum quality) of the sensor/actuator monitoring equipment is specified in the form of ignition prevention levels (IPL).
plain bearing, pump, agitator, vacuum pumps
Marking Ex nR Gc II 3 G in accordance with IEC 60079-0 Marking fr II 3 G in accordance with EN 13463-1 Principle
The enclosures are designed in such a way that the ingress of gases is restricted.
The powerloss in the enclosure may, if it contains sparking components, only lead to a temperature increase compared to the surrounding of 10 K. Equipment with these enclosures must allow monitoring of the vapour tightness and tightness after installation and maintenance. The allocation to the temperature class by the external surface temperature applies to all enclosures with and without sparking components. It must not be possible for elastic seals to become mechanically damaged under normal operating conditions; they must maintain their sealing properties over the service life of the equipment. Cast seals must permit a permanent operating temperature 10 K compared to the maximum operating temperature.
Switchgear, measuring and monitoring instrumentation and information systems and equipment . Complex machinery, Large machines
Devices which do not fully comply with a type of protection but assure comparable safety Marking Ex s II 1/2/3 G in accordance with IEC 60079-0
The rules for the marking of systems, equipment and components are uniformly defined in the standards relating to the general technical requirements (EN 60079-0 ff. electrical equipment or EN 13463-1 ff. mechanical equipment). Because the European Community has agreed in the future to also formulate uniform requirements and to introduce a uniform classification for devices, systems and components, other than electrical equipment, the marking has also been unified. Additional symbols have been introduced. This has been defined in the Directive 94/9/EC on "Devices and protective systems for use in hazardous areas". The complete marking on operating equipment is composed accordingly of the requirements set out in Directive 94/9/EC and the requirements in the IEC/EN standards. To some extent, both sources define the same requirements and consequently some of the information on the label is redundant. If and when this double information will be compared and adjusted is not assessable. A priority for all Ex equipment and protective systems is that the marking should show the areas of their designated use.
The marking must indicate the following The manufacturer who has put the item of equipment on the market. A designation which allows it to be identified. The application zone underground I other areas II, gases and vapours - G -, dust - D - or mines - M The categories which indicate whether the device is only suitable for specific zones. The type(s) of protection the equipment fulfils. The explosion group, and if required, the explosion subgroup for which it is suitable and The temperature class for which the piece of equipment is suitable The test laboratory where the test certificate was issued, the standard or revision of a standard applicable to the piece of equipment including the registration number of the certificate at the test laboratory, and, if necessary, which special conditions must be observed. In addition, the information which is required for a similar device of industrial construction must be available. In accordance with Directive 94/9/EC the future marking for all equipment will be as follows:
II 2 G - gas/vapour II 2 D - dust
notified body who - if required - certified the QA system or the products
The following equipment groups are distinguished
Equipment group Category Gases, vapours Dusts II other areas 2 suitable for zone 1, 21 marking with prefix G marking with prefix D 35
Example of a marking in accordance with RL 94/9/EG and EN 60079-0 ff Gas/vapor Electrical equipment
2 6 7 8 9 10 16
Typ 07-3513
II 2G Ex de IIC T6 Gb II 2D Ex t IIIC T80C Db IP6X PTB 00 ATEX 1068 X
-40C < Ta < +60C -20C < Ta < +60C Ui 690 V
Conformity mark Identification number of the notified body which where required certified the QA system or examined the products Ex mark Equipment group II - other areas (non-mining) Equipment category 2 - gases/vapours G, suitable for Zones 1 and 2 Explosion protection in conformity with the IEC/EN 60079-0 ff Type of protection: flameproof enclosure and increased safety Explosion group IIC (non-mining, Group C) Temperature class T6
10 Equipment protection level Gb (high protection level) 11 Certifying bodys symbol 12 Equipment certified in 2000 for the first time. 13 ATEX generation 14 Notified body identification number 15 If present: 1. "X" observe special conditions: e.g. "the light module must be installed in a way that ensures its mechanical protection from impact energy in accordance with EN 60079-0". 2. "U" Ex Component which is not intended to be used alone. CE conformity is certified when installed into a complete operating equipment. 16 Ambient temperature
Example of a marking in accordance with RL 94/9/EG and EN 60079-0 ff Dust Electrical equipment
2 6 7 8 9 10 11 17
Conformity mark Identification number of the notified body which where required certified the QA system or examined the products Ex mark Equipment group II - other areas (non-mining) Equipment category 2 - dusts D, suitable for Zones 21 and 22 Explosion protection in conformity with the IEC/EN 60079-0 ff Type of protection: protection by enclosure Explosion group IIIC (conductive types of dust) Max. surface temperature 80 C
10 Equipment protection level Db (high protection level) 11 IP protection 12 Certifying bodys symbol 13 Equipment certified in 2000 for the first time 14 ATEX generation 15 Notified body identification number 16 If present: 1. "X" observe special conditions 2. "U" Ex Component which is not intended to be used alone. CE conformity is certified when installed into a complete piece of operating equipment. 17 Ambient temperature
Designated area of use of equipment and components according to equipment group and equipment category / equipment protection level Hazardous area
Conditions and subdivisions Flammable materials Temporary behaviour of explosive atmosphere Required marking on the usable equipment Classification Equipment Group of hazardous as defined in areas directive 94/9/EC zone 0 zone 1 zone 2 II II II Equipment category as defined in directive 94/9/EC 1G 2G or 1G 3G or 2G or 1G 1D Equipment group as defined in EN 60079-O II II II Equipment protection level (EPL) as defined in EN 60079-O Ga Gb or Ga Gc or Gb or Ga Da
is present continuously or for long periods or frequently arises in normal operation occasionally is not likely toarise in normal operation, or if it does, will persist for a short time only
is present in the form of a cloud continuously, or for long periods or frequently occasionally develops into a cloud during normal operation is not likely to develop into a cloud during normal operation, or if it does, for a short time only
Db or Da
3D or 2D or 1D
Dc or Db or Da
methane carbon dust
operation where there is a risk of explosion disconnection where there is a risk of explosion
M1 M2 or M1
Ma Mb or Ma
-Conformity to the directive 94/9/EC
According to the equipment category, the Directive regulates which method the manufacturer must adhere to issue the Declaration of Conformity. The following overview shows these methods for the different categories.
Conformity Assessment Procedure Methods for Conformity and for marking
Equipment of Groups I & II, Categories M1 and 11 and Autonomous Protective Systems
Equipment of Groups I & II, Categories M2 and 21
Equipment of Group II, Category 31
Internal combustion engine or electrical equipment
EC type Examination Annex III
EC type Examination Annex III Internal control of production Annex VIII Internal control of production Annex VIII
Production QA Annex IV or
Product Verification Annex V
Conformity to type Annex VI or
Product QA Annex VII
Communicate a technical documentation to a Notified Body
CE mark with ID number2
CE mark without ID number2
and their components and devices, if separatly assessed. ID number of the notified body, which approved the QA system or verified the products. 39
The texts in Directives 1999/92/EC and 94/9/EC as well as further information on the directives and on explosion protection themes can be found on the following web pages: Informations Link
For the manufacturers ATEX website Actual Version of Directive 94/9/EG in all EU languages Guideline to the 94/9/EC Directive in English and German Last publication of standards harmonised under ATEX (OJ) http://ec.europa.eu/enterprise/sectors/mechanical/atex/index_en.htm http://ec.europa.eu/enterprise/sectors/mechanical/documents/legislation/atex/ http://ec.europa.eu/enterprise/sectors/mechanical/documents/guidance/atex/application/ http://ec.europa.eu/enterprise/sectors/mechanical/documents/standardization/atex/
For the operators ATEX website Actual Version of Directive 1999/92/EG in all EU languages Guide for the implementation of the 1999/92/EC Directive http://ec.europa.eu/enterprise/sectors/mechanical/atex/index_en.htm Suche ber: http://eur-lex.europa.eu/RECH_menu.do http://www.bartec.de/homepage/deu/downloads/produkte/exschutz/Leitfaden_1999_92_EG.pdf
In Germany Text of the Ordinance on Industrial Health and Safety (BetrSichV) Technical regulations for safety in the workplace (TRBS) Guidelines for the Ordinance on Industrial Health and Safety (LASI) http://www.bmas.de/DE/Service/Gesetze/betrsichv.html http://www.baua.de/de/Themen-von-A-Z/Anlagen-und-Betriebssicherheit/TRBS/ TRBS.html_nnn=true http://lasi.osha.de/de/gfx/publications/LV35_info.htm
BARTEC protects people and
the environment by the safety of components, s y s t e m s and plants.
Max-Eyth-Strae 16 97980 Bad Mergentheim
Phone: +49 7931 597-0 Fax: +49 7931 597-119
info@bartec.de www.bartec-group.com
UK-D-EXC700197-07/11-BARTECWerbeAgentur-126172
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