Introduction to the European ATEX directive Explosive atmospheres
Author : John Hill of Parker Hannifin
10 July 2012
Directive 9/9/EC defines an explosive atmosphere as a mixture of:
a) Flammable substances – gases, vapours, mists or dusts
b) With air
c) Under specific atmospheric conditions
d) In which, after ignition has occurred, combustion spreads to the entire flammable mixture
(NB: with regard to dust, it may be that not all dust is combusted after ignition has occurred)
An atmosphere with the potential to become an explosive atmosphere during operating conditions and/or under the influence of the surroundings is defined as a potentially explosive atmosphere. Products covered by directive 9/9/EC are defined as intended for use in potentially explosive atmospheres.
Harmonised European ATEX standard
The European Union has adopted two harmonised directives in the field of health and safety. The directives are known as ATEX 100a and ATEX 17.
Directive ATEX 100a (9/9/EC) lays down minimum safety requirements for products intended for use in potentially explosive atmospheres in European Union member states. Directive ATEX 17 (99/9/EC) defines minimum requirements for health and safety at the workplace, for working conditions and for the handling of products and materials in potentially explosive atmospheres. This directive also divides the workplace into zones and defines criteria by which products are categorised within these zones.
The ATEX directive has been in force throughout the European Union since 1 July 00, replacing the existing divergent national and European legislation relating to explosive atmospheres.
Please note that for the first time, the directive covers mechanical, hydraulic and pneumatic equipment and not just electrical equipment as before.
With regard to the Machinery directive 98/7/EC, note that a number of external requirements in 9/9/EC refer to hazards arising from potentially explosive atmospheres, where the Machinery directive only contains general requirements relating to explosion safety (Annex I 1.5.7).
As a result, directive 9/9/EC (ATEX 100a) takes precedence over the Machinery directive with regard to explosion protection in potentially explosive atmospheres. The requirements in the Machinery directive are applicable to all other risks relating to machinery. In most cases full certification is not required, a much more simple "Risk Assessment" as detailed in the Directive, for the products to be supplied will suffice. At the moment we are conducting "Risk Assessments" in accordance with the Directive, on a broad range of core products, which will be published on the web site. A more limited range of products will have the full ATEX certification where this is deemed necessary.