ATEX directive

The ATEX directives are two EU directives describing the minimum safety requirements for workplaces and equipment used in explosive atmospheres. The name is an initialisation of the French term "Appareils destinés à être utilisés en ATmosphères EXplosives" (French for "Equipment intended for use in explosive atmospheres").
Directives.
Organisations in the EU must follow Directives to protect employees from explosion risk in areas with an explosive atmosphere.
There are two ATEX Directives (one for the manufacturer and one for the user of the equipment):
Note: The ATEX 95 "equipment" Directive 94/9/EC, was withdrawn on 20 April 2016 when it was replaced by ATEX 114 Directive 2014/34/EU. ATEX Directive 2014/34/EU is mandatory for manufacturers as of 20 April 2016 as stated in article 44 of the Directive.
ATEX Directive 2014/34/EU was published on 29 March 2014, by the European Parliament. It refers to the harmonisation of the laws of the Member States relating to equipment and protective systems intended for use in potentially explosive atmospheres. 
Regarding ATEX 99/92/EC Directive, the requirement is that Employers must classify areas where potentially explosive atmospheres may occur, into zones. The classification given to a particular zone, and its size and location, depends on the likelihood of an explosive atmosphere occurring and its persistence if it does.
Equipment in use before July 2003 is allowed to be used indefinitely provided a risk assessment shows it is safe to do so.
The aim of Directive 2014/34/EU is to allow the free trade of ‘ATEX’ equipment and protective systems within the EU by removing the need for separate testing and documentation for each member state.
The regulations apply to all equipment intended for use in explosive atmospheres, whether electrical or mechanical, including protective systems. There are two categories of equipment 'I' for mining and 'II' for surface industries. Manufacturers who apply its provisions and affix the CE marking and the Ex marking are able to sell their equipment anywhere within the European Union without any further requirements with respect to the risks covered being applied. The directive covers a large range of equipment, potentially including equipment used on fixed offshore platforms, in petrochemical plants, mines, flour mills and other areas where a potentially explosive atmosphere may be present.
In very broad terms, there are three preconditions for the directive to apply: the equipment a) must have its own effective source of ignition; b) be intended for use in a potentially explosive atmosphere (air mixtures); and c) be under normal atmospheric conditions.
The directive also covers components essential for the safe use and safety devices directly contributing to the safe use of the equipment in scope. These latter devices may be outside the potentially explosive environment.
Manufacturers/suppliers (or importers, if the manufacturers are outside the EU) must ensure that their products meet essential health and safety requirements and undergo appropriate conformity procedures. This usually involves testing and certification by a ‘third-party’ certification body (known as a Notified Body e.g. Vinçotte, Intertek, Sira, Baseefa, Lloyd's, TUV ICQC) but manufacturers/suppliers can ‘self-certify’ Category 3 equipment (technical dossier including drawings, hazard analysis and users manual in the local language) and Category 2 non-electrical equipment, but for Category 2 the technical dossier must be lodged with a notified body. Once certified, the equipment is marked by the ‘CE’ (meaning it complies with ATEX and all other relevant directives) and ‘Ex’ symbol to identify it as approved under the ATEX directive. The technical dossier must be kept for a period of 10 years.
Certification ensures that the equipment or protective system is fit for its intended purpose and that adequate information is supplied with it to ensure that it can be used safely. There are four ATEX classification to ensure that a specific piece of equipment or protective system is appropriate and can be safely used in a particular application: 1. Industrial or Mining Application; 2. Equipment Category; 3. Atmosphere; and 4. Temperature.
The ATEX as an EU directive finds its US equivalent under the HAZLOC standard. This standard given by the Occupational Safety and Health Administration defines and classifies hazardous locations such as explosive atmospheres.
Technical definitions.
In DSEAR, an explosive atmosphere is defined as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapours, dusts or fibres in which, after ignition has occurred, combustion spreads to the entire mixture.
Atmospheric conditions are commonly referred to as ambient temperatures and pressures. That is to say temperatures of −20 °C to 40 °C and pressures of 0.8 to 1.1 bar.
Zone classification.
The ATEX Directive covers explosions from flammable gas/vapours and combustible dust/fibres (which, contrary to common perception, can lead to hazardous explosions)
Hazard – Gas/vapour/mist
Hazard – dust/fibres
Effective ignition source is a term defined in the European ATEX directive as an event which, in combination with sufficient oxygen and fuel (gas, vapour, dust or fibres), can cause an explosion. Methane, hydrogen or coal dust are examples of possible fuels.
Effective ignition sources are: