Directive imposes new obligations for explosive atmosphere equipment

Spark test apparatus for testing intrinsically safe circuits.

Although seagoing vessels and mobile offshore units and the equipment that they carry are excluded from the directive, it will nevertheless impact the equipment used also on these installations. This is because equipment certified according to the directive is foreseen to be used in the same way as equipment is used currently according to the old directives.

Equipment passed according to the old directives can continue to be placed on the market and put into service until June 30, 2003. After that date, however, the new ATEX directive is mandatory for all equipment placed on the market and put into service within the European Union. The new directive also imposes CE-marking and the EC declaration of conformity for explosion-protection equipment.

Through the CE-marking, the manufacturer attests to the relevant national authorities in the EU that requirements according to all applicable directives are fulfilled. For directives subject to transitional periods, information specifying applied directives must be presented in the documentation that accompanies the equipment. In addition to CE-marking, the EX mark that accords with the old directives must also accompany equipment. There are other changes that apply through the ATEX directive:

* It covers not only electrical equipment, but also other equipment with potential ignition sources such as mechanical impact, electrostatic discharges and overheating.

* It covers equipment for all zones (not just zone 1.

* It introduces new conformity assessment procedures for the equipment, and requirements are specified for notified bodies involved in the procedures.

* It also includes protective systems intended to halt incipient explosions immediately and/or limit the effects of an explosion

* It specifies a set of essential health and safety requirements relating to the design and construction of equipment and protective systems, rather than promptly referring to harmonised European standards as is the case with the old directives.

Products covered

The new directive applies to equipment and protective systems for places endangered by flammable gas, vapour, mist or dust. It also covers safety, controlling and regulating devices intended for use outside potentially explosive atmospheres, but still regarded as necessary for safety. Amongst equipment excluded from the directive is personal protective items covered by the directive 89/686/EEC.

The equipment is classified in equipment group I (gassy mines) and equipment group II (other applications). Group II is subdivided into G (gas) and D (dust).

Classification of explosion-protected equipment in categories 1, 2 or 3 is based on the connection between the probability of the occurrence of an explosive atmosphere (zone) and the integrity of the explosion-protected equipment (category). Category 1 equipment represents a very high level of protection, category 2 a high level and category 3 a normal level.

One of the aims behind the proposal for an upcoming European standard for electrical equipment category 1 (for use in zone 0) is to consider equipment certified for double protection - with two different types of category 2 protection applied - as category 1 equipment. In the event of failure of one means of protection, a second independent means should provide the protection level as required by the directive.

Conformity assessment procedures

The ATEX directive specifies numerous procedures for assessing conformity of equipment to the directive's requirements. For example, category I and II electrical equipment and internal combustion engines need to be certified (EC-type examination or unit verification) by a notified body. Alternative procedures for surveillance of the manufacturer's production process also apply. Category 1 mechanical, hydraulic and pneumatic equipment that could have a potential ignition source needs to be certified and subject to production surveillance by notified bodies).

For category 3 equipment, the manufacturer may verify and declare compliance with essential health and safety requirements himself, according to the procedure for internal control of production. Under this procedure, the manufacturer must keep a set of technical documentation within the EU available on request from relevant national authorities. This documentation should enable conformity of the equipment with the directive's relevant requirements to be assessed.

Design and marking

Annex II of the new directive sets out the essential health and safety requirements to be met by equipment and protective systems. Among these:

* equipment must be designed with due regard to technological knowledge of explosion protection so that they can be safely operated throughout their foreseeable lifetime.

* equipment that may be exposed to certain types of external stresses must be furnished, where necessary, with additional means of protection.

* dangerous overloading of equipment must be prevented at the design stage by means of integrated measurement, regulation and control devices: these include over-current cut-off switches, temperature limiters, differential pressure switches, flowmeters, time-lag relays, overspeed monitors and/or similar types of monitoring devices.

* potential ignition sources such as sparks, flames, electric arcs, high surface temperatures, acoustic energy, optical radiation, electromagnetic waves and other ignition sources must not occur.

For the design and testing of equipment and protective systems, harmonised European standards may be used. Compliance with such standards enables a product to be presumed to meet the essential requirements.

Swedish implementation

The ATEX directive has been implemented in Sweden as a regulation ELSAK FS-1995:6 for electrical equipment and as a regulation AFS 1995:5 for other equipment. The Swedish National Testing and Research Institute (SP) is a notified European certification centre for explosion-protected equipment. SP has also applied for notification according to the new ATEX directive.

SP has extensive experience in testing, certification and standardisation work according to European Cenelec and global IEC standards, including equipment for the offshore sector. Through its wide-ranging expertise and test resources, SP will continue offering a high level of testing and certification services under the new directive.

The EU Commission has proposed another new directive covering health and safety of workers at risk from explosive atmospheres. This would be based on Article 118a of the EC Treaty. It introduces requirements for improvements in health and safety and describes obligations for employers concerning both organisational and technical aspects of the workplace.

The applied principles for explosion protection should be, in the first place, to prevent the formation of explosive atmospheres; secondly, to prevent the ignition of such atmospheres; and thirdly, to minimise the effects of explosions.

The employer is obliged to assess the risks involved and to draw up an explosion protection document. Places where workers could be at risk from explosive atmospheres shall be classified in zones 0, 1 or 2 for gas, vapours and mists or in zones 20, 21 and 22 for dust. Use of Eex equipment according to the new ATEX directive 94/9/EC is related to these zones.

A new worldwide certification scheme has been developed by IEC and is now being established. The IECEx scheme aims to eliminate the need for multiple national certification of electrical equipment intended for use in explosive atmospheres.

The final stage of the IECEx scheme is worldwide acceptance of one standard (IEC standard), one certificate (IECEx certificate) and one mark for Ex equipment (IECEx mark) to facilitate international trade and use in this sector. The certificate will attest conformity of the equipment to the IEC standard and that the manufacturer operates a quality system according to ISO 9002.

Apparently there is a conflict for the EU between the IECEx scheme and the requirements according to the new ATEX directive for Ex equipment. This will be accentuated in 2003 when all EU countries must follow the new directive - unless the problem has been solved by then through GATT-type agreements. A worldwide certification scheme has been provided by IEC, however: whether it will be used or not by large regional trade blocks such as the US and Europe depends now on the parties concerned.

For more information contact Peter Bremer, SP: telephone +4633 165405 or fax +46 33 125038.