Hazardous Area Certification
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 prepared by IEC TC31. IECEx is about giving confidence that a product or service meets clearly defined transparent criteria. It’s aim is to harmonise standards to allow free movement of goods by establishing a world-wide accepted standard. This will result in a single set of standards, a single certificate and a single mark. The benefits of the scheme are obvious – shorter certification lead-times, and the opening up 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.
As opposed to ATEX, IECEx has been made from the outset as a Type 5 Certification Scheme, relying on a single third party to bring together all aspects of design and production control before issuing a publicly available Hazardous Area Certification. Thus the public domain documentation is a certificate issued by the certification body. Furthermore, because of the online IECEx database, any purchaser of the equipment can check the current status of the certificate on the web.
For Australia: Australian standard AS/NZS 60079 is harmonized with IEC 60079, so that the national certificate of conformity (ANZEx) is accordingly fully harmonized 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. Note: IECEx does not cover the requirements for general electrical compliance in Australia (RCM Mark).
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 and IECEx, especially for Zone 1 approvals, is the norm in most instances.
Protection Concepts – ways to make a device safe for use in a hazardous area
This is an area of major confusion for many of our customers, caused mostly by the use of incorrect terms or limited knowledge of the ways in which a device can be made ‘safe’. The term ‘intrinsically safe’ is often used when requesting equipment, however this is actually only one of several methods which can be employed to ensure that an electrical piece of equipment can be operated or used in a potentially hazardous environment.
The method selected by a manufacturer to make a piece of equipment safe is typically driven by the way it is to be used, and the relative pros and cons of the functionality of the device. Some of these are obvious when you think about it. For example, it would be impossible to render a mobile device safe using the protection concept of oil-immersion (o). Similarly, a large electrical motor can hardly be rendered safe using intrinsic safety, which demands that operating currents and voltages must be extremely low. Others are less obvious; you could, for example, fill a standard computer or phone full of quartz sand (q) and make it safe, but what would the effect of that powder have on the weight, or the wear and tear on sensitive electronic components inside the device, not to mention the issues presented when it needs repair?
The table below shows the various types of protection and the concepts or methods used in each case. The symbol for each type must be shown as part of the device markings.
Hazardous Area Zones
So now we understand the various ways to make a device safe, what are these Zones all about?
Zones are a method of identifying the potential risk based solely on the presence of the flammable substance (gas / dust) 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 in a particular Zone must meet the standards of testing for that Zone. So while a Zone 1 certified device can be used safely in either Zone 1 or 2, it cannot be taken into a Zone 0 area. Consequently, Zone 2 certified devices must be introduced with caution into well defined / separated areas if the facility also includes Zone 1 or Zone 0 areas. See the following chart which shows the zones under both IECEx / ATEX and the North American system of Classes & Divisions.
Areas where potentially explosive liquids, gases or dust are being produced, refined or where some repeated contact is likely are generally classified as Zone 1. Conversely, examples of Zone 2 areas are storage areas, maintenance workshops and other ancilliary areas adjacent to the main production areas.
Potentially flammable gases or dusts can spontaneously ignite under several conditions, and temperature is a major factor. Consequently, devices used in potentially hazardous areas are tested under fault conditions and classified into temperature (‘T’) classes depending on their ability to maintain a maximum permitted surface temperature, which is identified as part of the required certification markings.
So you have a ex-certified device, but what do all those hazardous markings mean? Let’s break it down…
A table is included below which breaks down the IECEx and ATEX codes to help you try and make sense of them. Note that when viewing ATEX device markings, in the wisdom designed to dumb-found mere mortals, the Equipment or ‘Device Category’ is expressed as a numeric value 1, 2 or 3. This should not be confused with the Zone it is intended to be used in, as Zone 0 = Category 1, Zone 1 = Category 2, etc.
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