ATEX is the name commonly given to the two European Directives for controlling explosive atmospheres, its name derived from the French: ATmospheres EXplosives. For example, Directive 99/92/EC (also known as ‘ATEX 137’ or the ‘ATEX Workplace Directive’) outlines the minimum requirements for improving the health and safety protection of workers potentially at risk from explosive atmospheres. The other: directive 2014/34/EU (previously 94/9/EC also known as ‘ATEX 95’ or ‘the ATEX Equipment Directive’) provides for approximation of the laws of Members States concerning equipment and protective systems intended for use in potentially explosive atmospheres.
In Great Britain the requirements of Directive 99/92/EC were put into effect through regulations 7 and 11 of DSEAR (Dangerous Substances and Explosive Atmospheres Regulations 2002). The requirements in DSEAR apply to most workplaces where a potentially explosive atmosphere may occur, as is the case with many finely divided powders. Some industry sectors and work activities are exempted because there is other legislation which fulfils the necessary requirements.
The onus for establishing the potential explosion risk and specifying ATEX zoning requirements of the equipment to operate safely with the material are part of ATEX137 is the legal responsibility of the end user of the equipment. Guidance on methodology of establishing appropriate zoning is set out in standard EN 60079-10-2:2015 “Explosive atmospheres. Classification of areas. Explosive dust atmospheres”.
Once the zone requirements are specified, it is the legal responsibility of the equipment manufacturer to supply equipment which is certified for use in the appropriate area. For non electrical ATEX category 1 equipment (zone 20) an independent notified body must be involved with the certification process. For category 2 (zone 21) the manufacturer’s technical file must be lodged with a notified body. For category 3 (zone 22) this may be self certified by the manufacturer.
Our team can advise when ATEX certification is likely to be required and what impact this will have on any of the relevant aspects of your equipment build.
If you are handling a potentially explosive material, then you will require ATEX approved equipment. It should be noted that the particle size distribution and concentration of particles forming a dust cloud has a great influence on how potentially explosive the atmosphere is. High concentrations of very fine particle size are much more explosive than coarser particle sizes, as such it is normal to have explosion indices testing carried out by an accredited laboratory on the specific powder formulation in question prior to equipment build.
Usually our milling and classification equipment, when used to mill or classify a potentially explosive product, will contain a potentially explosive atmosphere continuously internally within the machine (zone 20). If the mill or classifier is integrated into a full production line where the product entering and leaving the system is enclosed, then externally an explosive atmosphere is not likely to occur in normal operation, but if it does occur, will persist for a short period only (zone 22). In some cases where a more manual product discharge or filling scheme is used, which is not fully enclosed, then externally an explosive atmosphere is likely to occur in normal operation occasionally (zone 21).
For large bespoke plants, these may sometimes be considered ‘installations’ rather than ‘equipment’, in these cases it is outside the scope of Directive 2014/34/E. In these cases the end user takes responsibility for the risk assessment and certification for the plant installation.