ATEX Directive

Any control equipment used to ensure the safe operation of equipment in a hazardous area falls within the scope of the ATEX Directive (from the French – ATmospheres Explosibles). The ATEX Directive combines two European Directives associated with equipment used in and people who work in potentially explosive atmospheres. It not only considers potentially explosive concentrations of gas, vapor or mist in the air, but also concentrations of dust. It accounts for both electrical and mechanical sources of ignition. It also concerns the minimum requirements for improving safety and health protection of workers at risk from explosive atmospheres. An Explosive Atmosphere is the mixture of flammable substances in the form of gases, vapors, mists or dusts with air.

ATEX Directive 94/9/EC (also known as ATEX 95 or ATEX 100A)
If you design, manufacture or sell any equipment or protective system intended for use in potentially explosive atmospheres, you must comply with the ATEX Directive 94/9/EC and the CE Marking Directive to market those products in the European Union (EU). This directive covers equipment¹ and protective systems², which may be used in hazardous areas created by the existence of flammable gases, vapors, mists or dusts. It also covers electrical and non-electrical equipment. The following types of products are excluded from the directive's requirements:

• Medical devices
• Products for the use in the presence of explosives
• Products for domestic use
• Personal protective equipment
• Sea-going vessels and mobile off-shore units
• Means of transport, except vehicles for use in potentially explosive atmospheres
• Military equipment
  

Essential Health And Safety Requirements (EHSR)
Equipment, protective systems and safety devices must satisfy the relevant essential health and safety requirements set out in Annex C of Directive 94/9/EC. The requirements take into account the intended use of the products and changes in technological knowledge as far as possible, with immediate utilization. They include general measures requiring manufacturers to take steps to prevent the formation of explosive atmospheres by the equipment, protective system or safety device; to prevent the ignition of an explosive atmosphere by electrical and non-electrical sources; and to ensure that, should an explosion occur, it can be stopped immediately or limited in extent. Other aspects covered: the materials used; design and construction; mechanical hazards and vibrations; safe opening; electrostatic hazards; hazards arising from external effects; and the integration of safety requirements.

Methods Of Complying With The Essential Health And Safety Requirements
Products must be manufactured in conformity with:

• Specified European harmonized standards; or
• Harmonized standards specified in the Electrical Equipment for Explosive Atmospheres (Certification) Regulations 1990; or
• In the absence of specified European harmonized standards, existing national technical standards and specifications may be used instead; or
• The essential health and safety requirements
  

When using any of the first three standards listed above, check that the standard(s) cover all of the essential health and safety requirements relevant to the product; and the standard(s) are to the current state of technical knowledge. In the absence of a relevant standard, a manufacturer must demonstrate conformity of the product with the requirement itself.

Classification of Equipment and Hazardous Areas
Equipment is divided into two groups (I for mining and II for surface industries) and into categories (M1and M2 for mining) and categories 1, 2 and 3 for all other industries.

ATEX Directive 99/92/EC (also known as ‘USE’ or ATEX 137) refers to the safety and health protection of workers potentially at risk from explosive atmospheres. The directive highlights what the employer must do to prevent and protect against explosions as well as classifies hazardous areas into zones, as defined below:

Gas, Mists or Vapors

• Zone 0 — An atmosphere where a mixture of air and flammable substances in the form of gas, vapor or mist is present frequently, continuously or for long periods.
  
• Zone 1 — An atmosphere where a mixture of air and flammable substances in the form of gas, vapor or mist is likely to occur in normal operation occasionally.
  
• Zone 2 — An atmosphere where a mixture of air and flammable substances in the form of gas, vapor or mist is not likely to occur in normal operation but, if it does occur, will persist for only a short period.
  

Dusts

• Zone 20 — An atmosphere where a cloud of combustible dust in the air is present frequently, continuously or for long periods.
  
• Zone 21 — An atmosphere where a cloud of combustible dust in the air is likely to occur in normal operation occasionally.
  
• Zone 22 — An atmosphere where a cloud of combustible dust in the air is not likely to occur in normal operation but, if it does occur, will persist for only a short period.
  
  

EC Type Examination Certificate
It is mandatory for manufacturers to obtain an EC (European Community) Type Examination Certificate from a notified body if they are manufacturing electrical equipment in Categories M1, M2, 1 and 2 or diesel engine protection systems in Category 2. In all other cases manufacturers are free to certify their own equipment. Depending on the equipment's categorization, manufacturers are required to install a quality system that ensures product replication. There are five (5) annexes in the ATEX Directive which identify different quality systems for this purpose. Manufacturers are required to have in place either an ISO 9000 quality management system or a notified body must be involved in the inspection of product in some capacity. In either case a notified body is responsible for ensuring that products produced meet the original EC Type Examination Certificate. Quality management systems must either be audited by the notified body (if EN 45012 accredited) or another organization that has this qualification and is accepted by the notified body.

Explosive Protection Document (EPD)
The directive also requires that an Explosive Protection Document be prepared and maintained which identifies hazards, evaluates risks and defines safety measures.

In addition to assessing the effect of any explosion the EPD must consider:

• Substitution of flammable products with non-flammable
• Training
• Permits to work
• Warning of explosive conditions
• Escape routes
• Power failure
• Manual overrides
• Emergency shutdown
• Co-ordination between workers in the area
• Installation and maintenance of equipment
• Permit to work systems
• Warning notices
• Policies and procedures associated with equipment for potentially explosive atmospheres.
  

Signs
The directive requires that all areas classified as hazardous be identified with a warning sign. The sign must be triangular, black on yellow with the text EX (see below). The signs must be displayed at points of entry into explosive atmospheres.

In addition to the 94/9/EC ATEX Directive, products for use in potentially explosive atmospheres may require to be compliant with other directives including the 89/336/EEC Electro-Magnetic Compatibility (EMC) Directive, which became mandatory on January 1, 96. This directive applies to virtually all electrical and electronic apparatus potentially able to generate interfering emissions or exhibit an undue sensitivity to interference sources.

Once compliance with the relevant directives is complete and an EC Declaration of Conformity is issued by the manufacturer, the "CE" mark may be applied and the product placed on the market (see below).

Conclusion
With the introduction of the ATEX Directive manufacturers now have an opportunity to introduce more innovative products than was possible under the old Explosive Atmospheres Directive. Compliance with the requirements of the ATEX Directive is complex. The directive sets a number of technical and quality objectives that must be complied with to the satisfaction of a notified body. However, once these have been met, a manufacturer is entitled to display the distinctive European Mark which is recognized throughout the European Union.

1 “Equipment” is any item which contains or constitutes a potential ignition source and which requires special measures to be incorporated in its design and/or installation in order to prevent the ignition source from initiating an explosion in the surrounding atmosphere. Also included in the term “equipment” are safety or control devices installed outside the hazardous area but having an explosion protection function. A wide range of products comes within the definition of equipment including electric motors, lighting fittings, control and communication devices and monitoring and detection equipment.

2 “Protection systems” are items, which prevent an explosion that has been initiated from spreading or causing damages. They include flame arresters, quenching systems, pressure relief panels and fast-acting shut-off valve.