The IEC 60079 series is a compilation of standards that cover all permitted protection techniques for equipment in potentially hazardous areas. It is maintained by the International Electrotechnical Commission (IEC) and has been generally adopted worldwide. IEC standards form the practical basis for the "Zone" system of classification, as opposed to the legacy North American "Division" system.
The IEC system has become the basis for international harmonization of hazardous locations equipment. As many countries have adopted these standards, this has significantly simplified the design and certification of hazardous locations equipment across the globe. This can represent a significant savings for companies who intend to market their products both domestically and internationally.
IEC standards have the disadvantage of not being perfectly uniform across all countries. The IEC scheme permits deviations by country. For example, the United States versions of the standards (the UL 60079 series) are very similar to the IEC 60079 standards, but are often not identical. Similar issues often exist for specific countries, especially with regards to documentation and markings. These country-specific changes can result in difficulties when trying to certify products for multiple markets.
Harmonization is still a work in progress, and there are areas where it is not yet complete. This has and can lead to some odd requirements or processes for achieving certification. To add to the confusion, both the United States and Canada still have many, many older installations still operating on legacy schemes, and customers are still demanding certification to the "old" Division standards. This can make it doubly difficult to know what standards to apply.
The IEC 60079 series is divided into many individual standards (or "parts"), not all of which are sequentially numbered. For example, IEC 60079-0 is Part 0 of the standard. Additional parts are introduced periodically and on an ongoing basis, while existing standards are regularly updated.
The first sections detailed the various construction and design requirements for apparatus intended for use in explosive atmospheres. There are also sections on repair and system design, as well as specific standards dealing with intrinsically safe Fieldbus, optical transmission, and performance requirements for flammable and oxygen gas detection systems.
Note that most of the individual equipment standards do refer back to 60079-0 (Part 0: General requirements). This markes IEC 60079-0 an essential reference for all types of hazardous locations design.
An often-overlooked detail of hazardous area equipment design is the corresponding ordinary location design - all hazardous area equipment must also comply with the applicable ordinary locations standards. In this sense, hazardous area standards stand "on top" of ordinary location requirements. This is usually not an issue for companies used to producing specific equipment, but can sometimes be missed when designing new or unfamiliar equipment.
In the IEC scheme, each type of protection is designated by a letter. In other words, the letter 'code' specifies what technique(s) were used during equipment design and installation to ensure safety. The letter codes are always lowercase and are usually written inside single quotes, such as 'i' and 'd', to distinguish them. This can be confusing initially, but is simple once the letter codes are understood.
A sampling of the more common IEC lettering codes is shown below. Please click on a protection type for more detail.
| Part |
Description |
|
| 60079-0 |
General requirements for all equipment |
| 60079-1 |
Equipment protected by explosionproof / flameproof enclosures (type 'd') |
| 60079-2 |
Equipment protected by pressurization (type 'p') |
| 60079-5 |
Equipment protected by powder filling (type 'q') |
| 60079-6 |
Equipment protected by oil immersion (type 'o') |
| 60079-7 |
Equipment designed to increased safety requirements (type 'e') |
| 60079-11 |
Equipment designed to intrinsically safe requirements (type 'i') |
| 60079-13 |
Equipment protection by pressurized room (type 'p') |
| 60079-15 |
Equipment designed to non-sparking / nonincendive requirements (type 'n') |
| 60079-18 |
Equipment protected by encapsulation (type 'm') |
| 60079-19 |
Repair, overhaul, and reclamation requirements |
| 60079-20-1 |
Material characteristics for gas and vapour classification - Test methods and data |
| 60079-25 |
Intrinsically safe electrical systems |
| 60079-26 |
Requirements for intrinsically safe systems |
| 60079-27 |
Requirements for intrinsically safe Fieldbus (FISCO) |
| 60079-28 |
Requirements for systems using optical transmission |
| 60079-29-1 |
Performance requirements for flammable gas detectors |
| 60079-29-2 |
Selection, installation, use and maintenance of flammable gas and oxygen detectors |
| 60079-29-4 |
Gas detectors - Performance requirements of open path detectors for flammable gases |
| 60079-30-1 |
Requirements for electrical resistance trace heating |
| 60079-31 |
Equipment protected against dust ignition by an enclosure (type 't') |
