Key ATEX Standards
Key ATEX Standards
The ATEX Equipment Directive sets out essential health and safety requirements, but it deliberately doesn't specify how to meet them technically. That's where harmonised standards come in. Using these standards creates a "presumption of conformity"—if your equipment complies with the relevant harmonised standard, it's legally presumed to meet the corresponding directive requirements. The EC ATEX Guidelines (§85-88) explain this relationship in detail.
The IEC 60079 Series
The IEC 60079 series forms the backbone of explosion protection standards worldwide. These international standards are adopted as European standards (EN 60079-xx or EN IEC 60079-xx) and harmonised under the ATEX directive. The most important standards include:
- EN/IEC 60079-0: General requirements for all Ex equipment—covering marking, documentation, environmental testing, and common requirements that apply regardless of protection type
- EN/IEC 60079-1: Flameproof enclosures (Ex d)—requirements for enclosures that contain internal explosions
- EN/IEC 60079-7: Increased safety (Ex e)—requirements for equipment that prevents ignition sources from occurring
- EN/IEC 60079-11: Intrinsic safety (Ex i)—requirements for circuits limited to energy levels below ignition thresholds
- EN/IEC 60079-2: Pressurised enclosures (Ex p)—requirements for enclosures that maintain positive pressure to exclude explosive atmospheres
- EN/IEC 60079-31: Dust protection by enclosure (Ex t)—requirements for enclosures that keep combustible dust out
Installation, Inspection, and Maintenance Standards
Beyond protection type standards, other standards in the series cover the complete lifecycle:
- EN/IEC 60079-10-1: Zone classification for gas atmospheres—methodology for determining zone type and extent
- EN/IEC 60079-10-2: Zone classification for dust atmospheres
- EN/IEC 60079-14: Electrical installation design, selection, and erection—how to properly install Ex equipment
- EN/IEC 60079-17: Inspection and maintenance—requirements for ongoing verification of installations
- EN/IEC 60079-19: Equipment repair, overhaul, and reclamation—standards for maintaining Ex equipment integrity
Non-Electrical Equipment Standards
For non-electrical equipment, the EN ISO 80079 series provides the framework. EN ISO 80079-36 covers general requirements, while EN ISO 80079-37 addresses specific protection concepts including constructional safety (c), control of ignition sources (b), liquid immersion (k), and flow restricting enclosure (fr).
Presumption of Conformity
Using harmonised standards significantly simplifies conformity assessment. A notified body examining equipment built to harmonised standards can rely on the presumption of conformity—reducing the depth of independent verification needed. Equipment not following harmonised standards requires the manufacturer to demonstrate equivalent safety through other means, which is typically more expensive, slower, and involves more scrutiny from the notified body.
Only standards listed in the Official Journal of the European Union as harmonised under the ATEX directive carry this presumption. Using a standard that exists but isn't harmonised—or using an outdated version after the transition period—doesn't provide the presumption.
Standard Revisions and Transitions
Standards are regularly revised. New editions may introduce different test methods, changed requirements, or updated marking. When a new edition is harmonised, there's typically a transition period during which both old and new editions can be used. After this period, only the new edition provides presumption of conformity.
Manufacturers must track which editions apply to their products and ensure certificates and documentation reflect current harmonised versions. Products certified to superseded standards may need re-examination or a new certificate when the transition period ends. The European Commission publishes updated lists of harmonised standards on its website—checking these regularly is part of maintaining compliance.
