Rules for Explosive Environments

Rules for Explosive Environments

Ex areas can be known by different names such as “Hazardous Locations”, “Hazardous Areas” “Explosive Atmospheres” and the like, and relate to areas where flammable liquids, vapours, gases or combustible dusts are likely to occur in quantities enough to cause a fire or explosion.

  Hazardous zones

Hazardous Zones are a method of identifying the potential risk based solely on the presence of the flammable substance (vapours, gases, dust, etc) under normal conditions. The higher the likelihood of the device being used when a flammable substance is present, the higher the risk, and conversely the lower the zone rating. Equipment intended for use within a hazardous zone must meet the required test standards for that Zone. These zones are determined by a set of standards, that also determine the requirements for which devices can be installed in which zone.

While each country has its own standards of conformance relating to Hazardous area Certification, the major standards and classification systems can loosely be combined as those relating to conformance standards based out of Europe, the US & Canada and the IECEx conformance initiative, which is the first attempt at reaching a globally harmonised standard.

    The IECEx scheme

The IECEx Scheme is an international Conformity Assessment Scheme covering Electrical Equipment for Explosive Atmospheres, as the internationally accepted means of demonstrating conformity with IEC Standards. The objective of the IECEx System is to facilitate a single set of standards to allow international trade of equipment and services for use in explosive atmospheres, while maintaining the required level of safety. The benefits of the scheme are obvious – shorter certification lead-times, and the opening of new markets with no (or very little) need for additional testing and assessment to satisfy national standards. It is limited specifically to electrical equipment only. Unfortunately, while many countries ‘accept’ IECEx, they have not harmonised their own national standards in line with IECEx in the same way, meaning the actual worldwide acceptance of IECEx is not as close as it may seem to be. As most of the world’s certified equipment is manufactured in Europe and the USA, the national standards of these countries are a manufacturers first choice for certification, although dual certifying devices to ATEX (USA) and IECEx, especially for Zone 1 approvals, is the norm in most instances.

  Australian standards

The Australian standard AS/NZS 60079 is harmonised with IEC 60079, so that the national certificate of conformity (ANZEx) is accordingly fully harmonised with the international certificate of conformity (IECEx). Equipment certified to IECEx can therefore be used almost without exception in Australia without the need for further testing or hazardous area approvals.