The abbreviation ATEX is derived from the French term “Atmospheres Explosibles” and covers two European Union Directives: 94/9/EC and 1999/92/EC.

Known previously as ATEX 100a, Directive 94/9/EC has been mandatory since 1st July 2003 for any equipment containing or constituting a potential ignition source.

The Directive has been incorporated into the national law of Member States and applies to sales of equipment, components and protective systems for use in potentially explosive atmospheres.

Directive 1999/92/EC, previously known as ATEX 118a, is now known as ATEX 137 and defines the minimum requirements for improving health protection and safety of employees who may be at danger from potentially explosive atmospheres.

This Directive applies to all operators of plant within potentially explosive atmospheres and to the building of new plant. A transitional phase for the adaptation of existing plant is in place until 31st December 2005.

What does it apply to?

Any equipment containing or constituting a potential source of ignition, requires preventative measures to be incorporated into its design or installation to prevent that ignition source from initiating an explosion within the surrounding atmosphere. The Directive applies to :

• Electrical and Mechanical equipment
• Protective systems and components

Consideration must therefore be given to all applications where there is a potential for the release of gases, vapour-mists and dust that may come into contact with any potential ignition source.

What products or industries are excluded?

The Directive explicitly excludes the following types of product:

• Medical devices
• Products for the use in the presence of explosives
• Products for domestic and non-commercial 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

What is the difference between the old certification and the new ATEX Directive?

The main differences are:

• The inclusion of non-electrical equipment
• The inclusion of dust atmospheres
• Additional quality system requirements
• The need to produce a “Technical Construction File”

ATEX 137 and the Operator

The ATEX 137 Directive requires the operator to prepare and maintain an “Explosive Protection Document” that assesses their plant, identifies potential hazards, evaluates the risks and defines appropriate protective measures. Under ATEX 137, plant areas must be classified into Zones, and Temperature Classes, Explosion Groups and ambient temperatures must be determined.