ATEX is a combination of the French words ‘Atmospheres‘ and ‘Explosibles’ which means ‘Potentially Explosive Atmospheres‘ and was realised with the introduction of the ATEX ‘equipment’ directive 94/9/EC, and the ATEX ‘workplace’ directive 99/92/EC.
This European Union (EU) legislation standardises how to safely build, install and operate equipment (mechanical or electrical) in potentially explosive atmospheres; to ensure that no harm can come to the people in the vicinity and the environment.
What is the background of ATEX?
ATEX is an EU legislation and as such is law and adherence to it is mandatory within the European Union.
Before the directive came into force the use of equipment in explosive atmospheres was mandated by national laws and working practices. Most of these are historically evolved from the experience gathered in the mining industry and were mostly limited to electrical equipment.
How is compliance with the ATEX directive shown?
Depending on the type of equipment (mechanical or electrical) and the equipment category (category 1, 2, or 3) the ATEX directive dictates that in some cases a notified body has to certify compliance to the directive whereas in other cases the manufacturer or importer into the EU can self-certify the equipment.
Table below shows which types of equipment can be self-certified by the manufacturer and which ones need the involvement of a notified body:
| Mechanical equipment | Electrical equipment | |
|---|---|---|
| Category 1 | Notified body | Notified body |
| Category 2 | Self-certification (technical file lodged with notified body) |
Notified body |
| Category 3 | Self-certification | Self-certification (technical file lodged with notified body) |
Notified bodies are conformity assessment bodies nominated by the European Commission, which is the legislative body within the EU.
To aid both the notified bodies and the manufacturers of equipment destined to be used in explosive atmospheres, harmonized standards have been written. Whilst the directive is law and defines the level of safety to be applied, standards give practical guidance to show how to comply with the directive, considering the state of the art technical solutions. EU standards are written and reviewed constantly by groups of technical experts in each EU member country.
The very basis of every ATEX certification for mechanical equipment is the Ignition Hazard Assessment based on EN80079-36 (EN= European Norm) in which the manufacturer assesses the possible ignition sources based on the likelihood that they become active. Vacuum pumps can be classed as mechanical equipment.
Depending on the equipment category required, measures have to be put in place to ensure that the ignition sources cannot become active during normal operation and during foreseeable or rare malfunctions.
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