In this July 2007 issue of VoltiBULLETIN, we cover the topic of the ATEX Directive - Hazardous and Potentially Explosive areas. Voltimum UK managing editor James Hunt introduces the topic:
The ATEX Directive also helps enable the free trading of ATEX products within the EEA by removing the need for separate documentation and testing for each individual European market. Manufacturers may use a single CE mark on their products to show compliance with this (and any other relevant) Directive.
Explosive atmospheres include mainly industrial locations such as mines, factories, agricultural silos, and oil and gas platforms, water and other chemical processing environments. Explosives manufacture and flammable - and potentially explosive mixtures of flammable gases with air - are not the only hazards. For example, flammable particles such as certain dusts suspended in the air are also potentially explosive. A flour mill is just one example of this, and serious accidents have occurred in such plant.
Equipment covered by the ATEX Directive:
In brief, such equipment covers a wide range of products that might be used in hazardous areas, or which are designed to be so. It includes control equipment, sensors and safety equipment, transformers, fans, pumps, compressors, lighting, and even fork lift trucks and other transport equipment such as cranes and locomotives.
More specifically, the Directive says that to remove barriers to trade, essential requirements regarding safety and other relevant attributes need to be defined by which a high level of protection will be ensured. These Essential Health and Safety Requirements (EHSRs) are listed in Annex II to Directive 94/9/EC. These EHSRs are specific with respect to the following equipment:
- Equipment and protective systems for use within potentially explosive atmospheres. Protective systems are devices 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. Examples include flame arresters, explosion relief systems, extinguishing barriers and explosion suppression systems.
- 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. These include autonomous protective systems intended to come into operation following an explosion with the prime objective to halt the explosion immediately, and/or limit the effects of explosion flames and pressure. They also include safety devices intended to contribute to the safe functioning of such equipment with respect to ignition source and to the safe functioning of autonomous protective systems.
- Components relating to the above.
In terms of electrical equipment, which is of most interest to Voltimum users, Directive 94/9/EC does not specifically define 'Electrical Equipment'. However, because such equipment is subject to its own conformity assessment procedure, a definition has, none-the-less, been provided that is generally accepted by the majority of Member States. This definition is: 'Electrical Equipment is equipment containing electrical elements, used for the generation, storage, measurement, distribution and conversion of electrical energy, for controlling the function of other equipment by electrical means or for processing materials by the direct application of electrical energy. It should be noted, that a final product assembled using both electrical and mechanical elements may not require assessment as electrical equipment provided the combination does not lead to additional ignition hazards for this assembly'.
The ATEX Directive and implementation:
There are actually two ATEX Directives. Directive 94/9/EC - 'Approximation of the laws of Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres' - is about equipment and protective systems intended for use in potentially explosive atmospheres. This Directive mainly concerns OEMs and suppliers, though there are certain aspects that affect end users - mainly related to spares and stocking availability.
With certain exceptions, this Directive covers all equipment and protective systems for hazardous areas and is not restricted to electrical equipment (as shown already). Earlier Directives only covered electrical equipment. Equipment capable of causing an explosion through its own potential sources of ignition must comply with the requirements of the Directive in order to be sold within the EC. Equipment which is not a potential source of ignition is outside the scope of the Directive. Already installed equipment does not need to be ATEX compliant as such, but it must be safe.
The second ATEX Directive, 1999/92/EC, is concerned with the minimum requirements for improving the safety and health protection of workers potentially at risk from exposure to explosive atmospheres. This Directive, therefore, affects all personnel operating plant or sites involving hazardous areas.
The ATEX Directive has been implemented in the UK by 'The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations (SI 1996 No.192)'. This came into force over a decade ago. These Regulations have since been amended by the 'Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres (Amendment) Regulations 2001 (SI 2001 No.3766') which came into force in December 2001. The amendment principally covers the concept of 'putting into service'. The Regulations (ISBN 0-11-053999-0) and the amendment to the Regulations (0-11-038961-1) are available to download from The Office of Public Sector Information (OPSI), or they can be ordered from The Stationery Office website. The Directive was also implemented separately in Northern Ireland in 1996 (SR 1996/247).
Since implementation, manufacturers had the option of complying with the Directive itself, or with existing Directives in this area, or with national regulations in force on 23 March 1994, during a transition period that ended on 30 June 2003. Manufacturers are now required to comply with the Directive. Earlier ATEX Directives, which covered only electrical equipment, were repealed from 1 July 2003, so that certificates of conformity under these 'old' Directives are no longer valid for new equipment from this date. Further guidance can be found on the EC website (http://ec.europa.eu/enterprise/atex/index_en.htm).
Compliance:
In terms of Directive 94/9/EC, compliance with the requirements for each category and group will normally need compliance with the essential safety requirements (and appropriate standards) for the different types of protection.
For electrical equipment in Categories 1 and 2, plus non-electrical equipment in Category 1, this will involve a Conformity Assessment Procedure and full certification of the equipment by an EC Notified Body. Electrical equipment of Category 3 (Zone 2 / Zone 22 use only), and non-electrical equipment from Categories 2 and 3, is marked with the equipment category as being compliant on the basis of the manufacturer's declaration. No third party certification is necessary.
The second ATEX Directive, 1999/92/EC, on the minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres, imposes requirements on site operators and employers. The Health and Safety at Work covers some of the aspects concerned, but this Directive has certain specific points that have to be addressed by site managers and employers. Directive r 1999/92/EC requires that measures are taken to ensure that work in explosive atmospheres can be carried out safely, and these measures must be co-ordinated with other employers. Its implementation in the UK is the responsibility of the Health and Safety Executive (HSE), and the regulations concerned are known as the Dangerous Substances and Explosive Atmosphere Regulations (DSEAR), which came into force in 2002 as Statutory Instrument 2002/2776. Download the Regulations from the HSE website (www.hse.gov.uk).
Assessment of explosion risks:
It is required that an assessment of explosion risks must be carried out. This must take account of whether it is likely that explosive atmospheres will occur, and whether they will persist. The likelihood that ignition sources, including electrostatic discharges, will be present must also be assessed. All such installations and processes must also be assessed. The same is true for all substances used in the process(es) concerned, as well as their possible interactions. Finally, the scale of possible dangerous effects must be predicted (as far as practicable).
An Explosion Protection Document must be written and kept up to date. This must show that any explosion risks have been assessed and that adequate measures have been taken to meet the requirements of the Directive. It must also show that those parts of a building or plant that are at risk, including those places where the minimum requirements are in force (see Annex II), have been classified into zones. Further, the Explosion Protection Document must show that workplace and all related work equipment are operated and maintained correctly. Finally, it should show that arrangements have been made for the safe use of work equipment in accordance with Directive 89/655/EEC.
Where the risk assessment shows it is necessary, it is essential that, if there is a power failure that could result in further risk, then related equipment and protective systems must be maintained in a safe state of operation completely independently of the rest of the installation. Also, manual overrides must be provided so that such systems can be shut down by hand if required. Only personnel competent to operate such equipment may do so.
For further reading, go to the EC's 'Guide to the implementation of directives based on New Approach and Global Approach' (Blue Guide). Go to http://ec.europa.eu/enterprise/atex/guide/#_ftn2 for the guidelines on the application of Directive 94/9/ec of 23 march 1994 on the approximation of the laws of the member states concerning equipment and protective systems intended for use in potentially explosive atmospheres, second edition July 2005 - updated May 2007. These new Guidelines are provided in .pdf format, as well as in html, the latter being updated as subject matters are resolved.
Voltimum users can find out more about the ATEX Directive and its ramifications by clicking on other parts of this VoltiBULLETIN. Click here to read the other articles in this bulletin.
