FEATURE HAZARDOUS AREA EQUIPMENT DIRECTIVE DIRECTION
The ATEX Directive sets the minimum standards for both the employer and the equipment manufacturer regarding explosive atmospheres. Here, Jean-Louis Evans, managing director at TÜV SÜD Product Service, offers some advice on compliance
Left: explosions can be caused by gas, vapours or mists, as well as dust. Employers and the self employed must carry out a risk assessment and record its findings in an ‘explosion protection document’
(dust) require Category 2, while zone 2 (gas) and 22 (dust) require Category 3 marked equipment.
EXPLOSIVE POTENTIAL Potential sources of ignition could be electric sparks, arcs and flashes, electrostatic discharges, electromagnetic waves, ionising radiation, hot surfaces, flames and hot gases, mechanically generated sparks, optical radiation, chemical flame initiation and compression. Moving parts in non-electrical
T
he ATEX Directive affects all manufacturers and their authorised
representatives in the EU, as well as the importers or any persons responsible for placing a product on the Common European Market. ATEX Directive 94/9/EC is a product
design and construction directive for equipment and protective systems intended for use in potentially explosive atmospheres, while ATEX Directive 99/92/EC covers the workplace. A new feature in Directive 94/9/EC stipulates that both electrical and non-electrical explosion hazards must be eliminated. The design and construction of
equipment falling under the ATEX Directive must be such that ignition of explosive atmospheres is prevented, or that its impacts are limited to an adequate level of safety. It is therefore vital that the design and construction of installations and machinery operated in potentially explosive atmospheres complies with the directive. The following products are affected by
the ATEX Directive - equipment, protective systems and components. As a visible sign of compliance with the
ATEX Directive, the CE marking must be affixed to each machine. This is not a consumer label, but addresses supervisory authorities to ensure free trade, as it is a product’s ‘passport’, which is valid throughout the EU. It indicates that the product complies with all relevant directives of the European Union and may be traded freely.
20 JUNE 2014 | ELECTRICAL ENGINEERING
CATEGORISATION AND CLASSIFICATION Within the directive, equipment is classified in two groups. Group I covers mining, while group II covers all other industries. Within each group a particular type of equipment is designated a category. Group II, Category 1 equipment is
intended for use where an explosive atmosphere is present continuously. Equipment within this category must be designed to ensure the very highest level of protection, considering rare and expected equipment faults. Group II, Category 2 is for equipment
that is intended for use where explosive atmospheres are likely to occur. It must provide the requisite level of protection, even in the event of frequently occurring disturbances or equipment failures that are considered to be the norm. Group II, Category 3 covers equipment
that is intended for use where explosive atmospheres are unlikely to occur, or occur infrequently and only for short time periods. This equipment must provide the requisite level of protection for normal operation. Employers must classify areas where
hazardous explosive atmospheres may occur, into zones. The zone’s classification depends on the likelihood of an explosive atmosphere occurring and its persistence if it does. Zone 0 (gas) and 20 (dust) are at the highest risk of an explosive atmosphere being present and require Category 1 equipment. Zone 1 (gas) and 21
equipment is a potential ignition source. Examples include gears, fans, pumps, compressors, mixers and brakes. However, mechanical equipment of this type usually has to be connected to a power source, which is also a source of ignition in itself. Both electrical and non- electrical equipment can be protected, such as limiting available power in the explosive atmosphere, flame-proofing equipment to withstand an internal explosion and using pressurisation. Explosions can be caused by gas, vapours
or mists, as well as dust. Employers and the self employed must carry out a risk assessment and record its findings in an ‘explosion protection document’. These measures have been taken to reduce or prevent the risk of explosions and to mitigate the effects of an explosion. It must also include details of the early warning devices, staff training, operational procedures and maintenance, operation of permits to work and co-ordination between employers. It is the employer’s responsibility to ensure a safe working environment, which includes taking the necessary arrangements for coordination when several organisations are operating at the same workplace. The effective prevention of the release of dangerous substances that create explosive atmospheres, as well as preventing sources of ignition to reduce the risk in the workplace, are fundamental to avoiding the potential severe consequences of an explosion. It is therefore vital that both equipment manufacturers and purchasers adhere to the ATEX Directive.
TÜV SÜD Product Service
www.tuv-sud.co.uk T: 01489 558 100
Enter 208 / ELECTRICALENGINEERING
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