The Equipment and Protective systems intended for use in Potentially Explosive Atmospheres (ATEX) Directive 94/9/EC of 23 March 1994, provides the essential health and safety requirements – leaving to standards developed by European standardization organizations their technical expression – and the relevant conformity assessment procedures before placing such equipment on the European market.
Directive 94/9/EC is also a total harmonization directive, since its provisions replace existing divergent national and European legislation which cover the same subjects as stipulated by Directive 94/9/EC. In this context, with effect from 1 July 2003 this Directive repealed: Council Directive 76/177/EEC (electrical equipment for use in potentially explosive atmospheres); Council Directive 79/196/EEC (electrical equipment for use in potentially explosive atmospheres employing certain types of protection); Council Directive 82/130/EEC (electrical equipment for use in potentially explosive atmospheres in mines susceptible to firedamp).
The general objective of the Directive is to eliminate or at least minimize the risks resulting from the use of certain products in or in relation to a potentially explosive atmosphere, i.e. an atmosphere, which could become explosive due to local and/or operational conditions. In particular, an explosive atmosphere for the purposes of ATEX Directive 94/9/EC is defined as a: Mixture with air, under atmospheric conditions, of flammable substances in the form of gases, vapors, mists or dusts in which, after ignition has occurred, combustion spreads to the entire unburned mixture.
To be within the scope of the ATEX Directive 94/9/EC, a product has to be:
- An equipment, as defined in Article 1.3.(a) of the Directive : machines, apparatus, fixed or mobile devices, control components and instrumentation thereof and detection or prevention systems which, separately or jointly, are intended for the generation, transfer, storage, measurement, control and conversion of energy and/or the processing of material and which are capable of causing an explosion through their own potential sources of ignition; or
- A protective system, as defined in Article 1.3.(b) of the Directive : devices other than components of the equipment defined above which are intended to halt incipient explosions immediately and/or to limit the effective range of an explosion and which are separately placed on the market for use as autonomous systems; or
- A component, as defined in Article 1.3.(c) of the Directive : any item essential to the safe functioning of equipment and protective systems but with no autonomous function; or
- A safety, controlling or regulating device as defined in Article 1.2. of the Directive : (…) intended for use outside potentially explosive atmospheres but required for or contributing to the safe functioning of equipment and protective systems with respect to the risks of explosion (…).
In addition, a product within the scope of ATEX directive may fall as well within the scope of other directives, which have to be applied in parallel. This may be the case of the following Directives: EMC (2004/108/EC), LVD (2006/95/EC), MSD (98/37/EC), PPE (89/686/EC), PED (97/23/EC) and CPD (89/106/EC).
As per article 1.4 of the Directive the following equipment are not within the scope of the Directive:
- Medical devices intended for use in a medical environment;
- Equipment and protective systems where the explosion hazard results exclusively from the presence of explosive substances or unstable chemical substances;
- Equipment intended for use in domestic and non-commercial environments where potentially explosive atmospheres may only rarely be created, solely as a result of the accidental leakage of fuel gas;
- Seagoing vessels and mobile offshore units together with equipment on board such vessels or units;
- Means of transport i.e. vehicles and their trailers intended solely for transporting passengers by air, road, rail or water networks, as well as means of transport in so far as such means are designed for transporting goods by air, by public road or rail networks or by water. Means of transport intended for use in a potentially explosive atmosphere are not excluded;
- Equipment covered by Article 346 (1)(b) of the Treaty on the Functioning of the EU (TFEU), i.e. designed and manufactured specifically for use by the armed forces or in the maintenance of law and order.
Only equipment and protective systems complying with Directive 94/9/EC and bearing the CE marking, which must be visibly affixed, may move freely throughout the European Union market.
Once the manufacturer has undertaken the appropriate procedures to assure conformity with the essential requirements of the Directive it is the responsibility of the manufacturer or his authorized representative established in the EU not only to affix the CE marking, but also to draw up a written EC Declaration of Conformity, and keep a copy within the EU for a period of ten years after the last equipment has been manufactured.
According to the Directive, in order to determine the appropriate conformity assessment procedure, the manufacturer must base the decision on the intended use of the product to identify as to which Group and Category it belongs:
Group I includes equipment intended for use in the underground parts of mines, and to those parts of surface installations of such mines, likely to become endangered by firedamp and/or combustible dust;
- Category M1: Products required to remain functional for safety reasons when an explosive atmosphere is present and characterized by integrated explosion protection measures functioning in such a way that: a) in the event of failure of one integrated measure, at least a second means of protection provides for a sufficient level of safety; or, b) in the event of two faults occurring independently of each other, a sufficient level of safety is ensured.
- Category M2: Products intended to be de-energized in the event of an explosive atmosphere. The protection measures relating to products of this Category provide a sufficient level of safety during normal operation even in the event of more severe operating conditions arising, from rough handling and changing environmental conditions.
Group II includes equipment intended for use in other places likely to become endangered by explosive atmospheres;
- Category 1: products designed to be capable of remaining within its operational parameters, stated by the manufacturer, and ensuring a very high level of protection for its intended use in areas in which explosive atmospheres caused by mixtures of air and gases, vapors, mists or air/dusts mixtures are highly likely to occur and are present continuously, for long periods of time or frequently.
Equipment of this Category is characterized by integrated explosion protection measures functioning in such a way that: a) in the event of a failure of one integrated measure, at least a second independent means of protection provides for a sufficient level of safety; or, b) in the event of two faults occurring independently of each other a sufficient level of safety is ensured.
- Category 3 comprises products designed to be capable of keeping within its operational parameters, stated by the manufacturer, and based upon a normal level of protection for its intended use considering areas in which explosive atmospheres caused by mixtures of air and gases, vapors, mists or air/dust mixtures are unlikely to occur and if they do occur, do so infrequently and for a short period of time only.
The design of the products of this category must provide a sufficient level of safety during normal operation.
After identifying to which Group and Category the product belongs, the appropriate conformity assessment procedure must be adopted:
- EC Type Examination:
- Provides a specimen of the envisaged production to a Notified Body which undertakes the necessary evaluation to determine that the “type” meets the essential requirements of Directive 94/9/EC and issues an EC Type Examination Certificate (Annex III);
- Quality Assurance Modules:
- Production Quality Assurance (Annex IV): Operates a quality system approved by a Notified Body for production, final equipment inspection and testing and is subject to on-going surveillance – applies to Equipment Categories 1 and M1 and to protective systems;
- Product Quality Assurance (Annex VII): A quality system approved by a Notified Body for the final inspection and testing of equipment subject to on-going surveillance – applies to electrical equipment and internal combustion engines only, in Equipment Categories 2 and M2.
- Verification modules:
- Product verification (Annex V): Examination and tests by a Notified Body of every product to check the conformity of the equipment, protective system or device with the requirements of Directive 94/9/EC and draw up a certificate of conformity – applies to Equipment Categories 1 and M1 and to the protective systems;
- Conformity to type (Annex VI): Tests carried out by a manufacturer on each piece of equipment manufactured to check the explosion protection aspects of the design. Carried out under the responsibility of a Notified Body – applies to electrical equipment and internal combustion engines in Equipment Categories 2 and M2;
- Unit verification (Annex IX): Notified Body examines individual equipment or protective system and carry out tests as defined in the harmonized standards, if they exist, or otherwise in European, international or national standards or conduct equivalent tests to ensure conformity with the relevant requirements of Directive 94/9/EC and draw up a certificate of conformity – may be applied at the option of the manufacturer as an alternative to any other conformity assessment modules.
- Internal control of production (Annex VIII): Product and quality system assessment procedure carried out by the manufacturer and retention of documentation – applies to equipment in Category 2 and M2 which is not electrical equipment nor internal combustion engines and to equipment Category 3.