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Question & Answers

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Q&A category: ATEX

Q:What is ATEX?

ATEX is the name given to two European Directives which regulate both the use and the manufacture and selling of equipment for use in potentially explosive atmospheres. The two Directives are:

  • 94/9/EC ?equipment and protective systems intended for use in potentially explosive atmospheres?
  • 99/92/EC ?minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres?

The word ATEX comes from the French and is an abbreviation for ?Atmosph?re Explosive?

Q:Where can I find the text of the European Directives on ATEX?

The directives can be found in all European languages on the EU website. The current addresses are:

Unfortunately the EU web addresses change constantly. If the above links are no longer valid, the quickest way to find the information is by searching with a web search engine such as Google rather than using the search engine on the EU web site.

Q:Why are there two Directives?

The two directives come under different Articles of the European treaty. Directive 94/9/EC is a so called ?Product Directive? and comes under the free trade article which ensures that products made in one European Country can be sold in all other countries in the EU. This Directives specifies essential safety requirements for equipment and is enacted in the same way in the national laws of all European countries. Directive 99/92/EC is a ?Social Directive? and comes under the article for encouraging improvements, especially in the working environment, to guarantee a better level of protection of the health and safety of workers. As such it sets minimum requirements, these requirements can be extended, or made more stringent, by individual national states. Currently there are no major differences in the national requirements specified following Directive 99/92/EC. The terms ?ATEX 95 and ?ATEX 137? (previously ATEX 100a and ATEX 118a) refer to the different articles of the European treaty which the two Directives come under. (The change in numbers came because the European treaty changed during the drafting of the Directives).

Q:Is there any guidance available from the EU on ATEX issues?

The EU published guidelines on the application of manufactures directive 94/4/EC in July 2005 (http://ec.europa.eu/enterprise/atex/guide/) these are under continuous update. Further information is also available in the EU good practice guide on directive 99/92/EC for users (http://eur-lex.europa.eu/smartapi/cgi/sga_doc?smartapi!celexplus!prod!DocNumber&lg=en&type_doc=COMfinal&an_doc=2003&nu_doc=515).

Q:What role do Standards play?

The manufacturers directive 94/9/EC is a so called ?New Approach? directive. As such the directive itself only specifies the essential safety and health requirements while possible technical solutions for achieving these requirements are contained in harmonised European standards.

Q:What is covered by the manufacturers Directive 94/9/EC?

The Directive applies to both electrical and mechanical equipment and protective systems intended for use in potentially explosive atmospheres. These include:

  • equipment and protective systems for use within potentially explosive atmospheres,
  • devices for use outside potentially explosive atmospheres, but which are required for, or contribute to the safe functioning of equipment and protective systems located inside such atmospheres and
  • components relating to the above.

Q:What is covered by the users directive 99/92/EC?

The ATEX Use directive is concerned with the safety of the workplace and places responsibility on the end user to risk assess their workplace and zone and mark hazardous areas according to their level of risk for gases and dusts. The zones correspond to the Group II Categories 1-3 in the ATEX equipment directive and enable end users to correctly specify to the manufacturers the intended use of ATEX products. Manufacturers can then supply the right category of ATEX equipment (certified under 94/9/EC) to be used within these zones.

Q:What equipment is covered by the manufactures directive 94/9/EC?

For a piece of equipment to come under the directive there must be some form of energy change, it must possess it own ignition source and it must be intended for use in a potentially explosive atmosphere. Thus a pipe, or silo, even if it intended for use in an explosive atmosphere does not come under the directive as they do not have their own ignition source. The potential electrostatic ignition source which may arise if the pipe or container is made from non-conducting material or from an unearthed (bonded to ground) metal pipe or container does not constitute an ignition source under the directive as this is caused by the use of the ?equipment? pipe or container rather than being inherently present. Similarly simple pieces of equipment such as valves are also excluded from the provisions of the directive (See the EU guidance referred to above).

Q:What equipment is not covered by the manufactures directive 94/9/EC?

In general the following equipment is excluded from the EPS Regulations: medical devices, equipment for domestic and non-commercial use, personal protective equipment, seagoing vessels and mobile offshore units, means of transport except where they are used in a potentially explosive atmosphere, for example fork lift trucks.

Q:What is the difference between a Declaration of Conformity and a Certificate?

A Declaration of Conformity is the document that the manufacturer must enclose with (or attach to) any equipment or protective system that is being sold in compliance with the requirements of the ATEX Directive 94/9/EC. The manufacturer has sole responsibility for creating this document and must do so in accordance with the detailed list of contents given at Annex X in the directive. The declaration complements the CE Marking which is applied to the product on the manufacturer?s responsibility.

A Certificate is normally the output of a process known as ?Certification?. There are many types of certification schemes, many involve the use of a third party certification body An ATEX product which has been subject to ?certification? will have either a ?EC-Type Examination Certificate? which is issued by an ATEX Notified Body (NB) following test and examination of a prototype, in accordance with Annex III of the directive. The name of the NB is incorporated in the certificate number marked on the product. Alternatively where the certification has been carried out on a voluntary basis (for example for Category 3 electrical equipment or Category 3 and Category 2 non-electrical equipment where certification is not mandated by the directive), the document is simply known as a ?Type Examination Certificate?.

Q:What are zones and categories and where is the difference between both?

Zones are places where hazardous explosive atmospheres may occur and are determined by an Area Classification Exercise. Which Zone applies depends on the frequency and duration that a potentially explosive atmosphere will be present. The different Zones are 0, 1 and 2 for places which may contain potentially explosive gas, vapour or mist / air atmospheres and 20, 21 and 22 for places which may contain potentially explosive dust / air atmospheres. The definitions for the different Zones are included in Annex I of the ATEX "User" Directive 1999/92/EC on minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres. Further help on carrying out an area classification is given in the EU Guide to Directive 99/92/EC and in the two standards:

EN 50281-3 Classification of areas where combustible dusts are or may be present and EN 60079-10 Electrical apparatus for explosive gas atmospheres - Part 10: Classification of hazardous areas.

Categories are the classification system used for different types of equipment and are defined in the ATEX "Manufacturer" Directive 94/9/EC. For non-mining, or Group II, equipment there are three categories 1, 2, and 3. The Category is a description of the likelihood that a piece of equipment will act as an ignition source.

Provided that a piece of equipment is suitable for use as appropriate in a potentially explosive gas or dust atmosphere (designated by the symbols "G" or "D"), the suitability of the different categories of equipment for use in particular Zones is given by:

Category 1 equipment is suitable for use in Zones 0, 1, 2 and Zones 20, 21, 22;

Category 2 equipment is suitable for use in Zones 1, 2 and Zones 21, 22;

Category 3 equipment is suitable for use in Zones 2 and Zones 22;

Q:Where can I find data on the explosion properties of dusts for example flour?
A:Explosion propeerties of dusts can be found under the following link, however you should take great care when using such data that the results correspond to your dust. The esplosion properties are change markedly by small changes in particale size, moisture content etc.
Q:What is the lower explosive concentration for wheat flour or grains in general?

La t?pica concentraci?n m?nima explosiva para polvos de cereales es 30-40 /m3

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