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Basic Concepts for Explosion Protection Basic Concepts for Explosion Protection

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Basic concepts for explosion protection Basic concepts for explosion protection This 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 14. revised edition - Version 2020 Authors: Dr.-Ing. Hans-Jürgen Linström Dipl.-Ing. Johannes Buhn Dipl.-Ing. Karel Neleman 2 Contents Technical development 6 - 8 Secondary 15 - 26 of explosion protection explosion protection Harmonization of explosion protection 8 Relevance and advantage of the area 15 classification in workplaces Explosion parameters 17 Explosion protection 9 - 14 Ignition temperature 17 Explosion 9 Equipment sub-groups 19 Basis for an explosion 9 for Gases/Vapours Protection principles 21 Three factors 10 Design standards and prevention 22 Explosion Range (limits) 13 of effective sources of ignition in devices Prevention of explosions 13 Standards for explosion protection 23 Primary explosion protection 14 Secondary explosion protection 14 Tertiary explosion protection 14 3 Basic concepts for explosion protection Types of protection 27-37 Marking 38-42 General requirements 27 Marking in accordance with Directive 38 2014/34/EU, the standards and the IECEx system Types of protection to 28 electrical equipment Marking in accordance with IECEx 39 Types of protection to 29 System based on ISO or IEC standards non-electrical equipment Increased safety 30 Application areas – equipment 40 Constructional safety 30 categories – equipment protection levels Intrinsically safe 31 Electrical equipment – gas/vapour 41 and dust Control of ignition sources 31 Encapsulation 32 Non-electrical equipment – gas/ 42 vapour and dust Non-incendive component 32 Hermetically sealed device 32 Sealed device 32 Conformity 43 - 45 Conformity Assessment Procedures 43 Liquid immersion 33 and CE Marking to Directive 2014/34/EU Pressurized enclosures 34 Conformity in accordance 44 with the IECEx System Restricted breathing enclosure 35 Comparison of ATEX and the IECEx 45 system Protection by enclosure 35 Flameproof enclosures 36 Powder filling 36 Special protection 37 Optical radiation 37 Electrical Resistance Trace Heating 37 4 5 Basic concepts for explosion protection Technical development of explosion protection Unwanted ignitions are older than mankind. Atmos- the flammable mixture present, while allowing com- pheric discharges – lightning – triggered fires long bustion inside the screen. When used correctly, the before humans walked the earth. In 1753 the first screens prevented an external ignition. lightning conductor was invented, enabling electro- static discharges as the sources of ignition for fires In the 19th century, electrical equipment was intro- to be significantly reduced. Lamps in mining also duced into industry and households. Immediately constituted another high fire risk for many years, afterwards, the occurrence of methane and coal because mine air mixed with methane – so-called dust in hard coal mining prompted the development firedamp – was able to cause explosions when of the basics of electrical explosion protection. sufficiently strong ignition sources were present. The advantages of electricity were so convincing In 1815 Sir Humphry Davy introduced the first mine that intensive work was carried out to find a way safety lamp, a non-electrical item of equipment for to reliably prevent contact between an explosive mining. Two wire glass screens arranged on top of atmosphere and ignition sources - originating from each other separated the flame - which was to be the use of electrical equipment - and thus prevent kept as small as possible inside the screen - from explosions. After bitter experiences in the beginning, the occur- rence of firedamp explosions was greatly reduced and well-monitored electrical equipment was uti- MANUFACTURER LEGISLATIVE lised with very high safety standards. Design standards Design regulations Today, fortunately, the number of accidents caused by electrical ignition sources is low. The expendi- ture 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 neglection is comparable to culpable carelessness. Unfortunately there are still numerous examples of explosions that demonstrate the devas- tating effects on humans, environment and plants. Priority is given to what is regarded as primary explosion protection, for example the focussing of attention on the use of non-flammable substances that are not capable of forming an explosive atmosphere. ALL THOSE INVOLVED Personal responsibility USER However, it is not always possible to exclude flam- and precautionary measures Directives mable 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. Such solution, by providing type(s) of protec- tion is referred to as secondary explosion protection. 6 These days, the construction of explosion proof The applications in the mining area were the equipment goes far beyond the field of electrical beginning. The utilisation and processing of mineral engineering. As will be demonstrated in the further oil and natural gas offer a wide scope for using descriptions, non-electrical equipment will also explosion proof equipment. Organic chemistry, the require testing or at least assessment. Here the paint industry and the pharmaceutical industry all knowledge gained by manufacturers over the process flammable liquids and gases. Because of decades on the explosion proof electrical equipment the production and utilisation of biogas and the is particularly important and it now also benefits the ecological utilisation of waste dumps, new applica- manufacturers of non-electrical equipment. tions are constantly developing. The utilisation of hydrogen is being discussed in depth, practised in There are many applications which require explo- experimental installations and will be in our lives as sion proof equipment. During the over 100 years renewable energy. of electrical explosion protection, principles and techniques have been developed which allow the use of electrical measuring technology, even where, for example in reaction vessels, an explosive atmos- phere is permanently present. 7 Basic concepts for explosion protection With the help of these standards, the manufac- Harmonization of turer is able to assume during the design and assessment of the explosion protection that he is explosion protection developing safe, protective systems, equipment and components in compliance with ATEX Directive Internationally, the standpoints on the explosion 2014/34/EU, which will then be tested in conform- protection of electrical and non-electrical equip- ance to uniform and binding inspection processes ment are co-ordinated by specialized IEC and ISO by an EU-authorized Notified Body. If the test cri- working groups. In the area of electrical engineering, teria have been met successfully, the Notified Body internationally harmonized design agreements issues the EU-Type Examination Certificates which were formulated in IEC standards at a very early ensure fulfilment in Europe of the uniform criteria stage. For the most part, this was done in con- with respect to the required Essential Health & formance with the CENELEC standards. A visible Safety Requirements (EHSR’s) for Equipment with sign of the harmonisation is that the relevant IEC/ a very high or high safety level. These EU-Type ISO (global), EN (Europe) documents on standards Examination Certificates are a prerequisite for the agree in content and in the registration number production and the placing on the market of protec- (60079 series). Harmonization is being worked on tive systems, equipment and components with very intensively at present. This reorganization involves high and high safety levels, indicated by Category 1 continuous amendments but will also make future and 2. international work easier. ISO/IEC working groups work in an identical way and use (80079 series) for For Category 3, with just an enhanced safety level, a application to non-electrical equipment. different approach is acceptable. The manufacturer may declare on his own responsibility that the Ex Under the IECEx System, Ex equipment is developed, Equipment or Ex Component complies, without tested and certified with a Certificate of Conformity involvement of a Notified Body. In the meantime (IECEx CoC) in accordance with the internationally more manufacturers are asking the Notified Bodies uniform requirements (IEC/ISO standards) and is in (on a voluntary basis) to examine the intended proto the meantime applicable to Ex equipment assem- types and issue Type Examination Certificates. blies consisting of electrical and non-electrical equipment too. A uniform classification of hazardous areas (instal- lations) provides a basis for selecting and assigning However, certificates are still accepted on the basis protective systems and Ex Equipment including of regional (for example in Europe with the manufac- their installation. Under EU Directive 1999/92/EC, turer’s EU Declarations of Conformity) and local (for an Explosion Protection Document
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