Over the last fifty years, industry has been marked by numerous disasters (Seveso, Toulouse, Feyzin). These have led to the tightening of regulations at both national and European level. This has resulted in precise and demanding directives, notably the creation of the ATEX EN 60079-10-1 zone. A number of risks need to be distinguished, including explosions and ignitions that can occur in ATEX zones. How do you determine ATEX zones in accordance with standard NF EN 60079-0-1?
What is the ATEX standard NF EN 60079-0-1?
The new version of standard NF EN 60079 : 10-1 relates to the zoning of gaseous EXplosive ATmospheres. It came into force at the end of 2018. This standard was created in 2009 and recently updated. It requires employers to subdivide zones where explosive atmospheres are present. This ensures the safety of personnel (Article R4227 of the French Labor Code).
The assessment and classification of gaseous ATEX zones is in fact part of the risk assessment. This assessment is required as part of the implementation of a DUER and a PPRT, and must be reviewed periodically.
The new version of the nf en 60079-10-1 standard therefore retains the principles of the previous version. It takes into account the 3 main factors used to determine the type and size of explosive zones:
- Sources of release
- Ventilation dilution capacity
- Ventilation availability
On the other hand, it introduces new calculation methods. These include ventilation levels and the design of ATEX zones.
For example, the previous version of the standard was based on the calculation of a theoretical flammable volume (Vz). Ventilation capacity is now assessed on the basis of ventilation velocity at the clearance level. The latter’s characteristics are also taken into account.
How does the ATEX zone work in practice?
Efficient zoning makes it possible to adapt or re-adapt the type of electrical and non-electrical equipment. This is done according to the type of zone, in order to limit risks.
The aim is to protect not only the premises, but also the employees.
According to current ATEX regulations, several zone categories can be distinguished:
- First, Zone 0: explosive atmosphere present permanently or over long periods during normal operation.
- Zone 1 : explosive atmosphere occasionally present during normal operation.
- Finally, Zone 2: explosive atmosphere present accidentally, in the event of malfunction or short-term operation.
This classification is basedon an analysis of the source of the release of flammable gas or vapors, and an analysis of the ventilation of the area where the release occurs.
A risk zone is therefore defined according to the frequency and duration of the presence of ATEX.
Once the zones have been determined, the industrial site manager is responsible for notifying premises and locations likely to present ATEX zones by means of a regulatory pictogram. Then, adopt ATEX equipment to prevent these industrial risks.
Do you work on an industrial site with ATEX zones?
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