Although there has recently been a change to the political standing of the UK with regards to its membership of the European Union, it’s likely that all regulations will stay in place for the foreseeable future.
What is ATEX?
ATEX is an acronym for the French term ‘ATmosphers EXplosives’. It covers the certification of equipment that is used in a hazardous area. The EU directive 94/9/EC requires that any electronic or electrical equipment is used within a hazardous area, it is compulsory that it has an ATEX certificate.
When there is a potentially explosive combination of flammable gasses, dust or air in an area, then this is classified as a hazardous area. This is something that also addressed outside of the EU area by the IECEX certification system. In North America the UL system is used and equipment that are suited to use in hazardous atmospheres are required to be labelled as such.
Considering hazardous areas and the likelihood of the presence of a potentially explosive atmospheres, the European, IECEX and the North American method all use a classification system for areas with gases and dusts.
The following is used to classify products for use in the ATEX approach:
| Heading | Mark | Use |
| Explosion proof |  |
in accordance with the ATEX directive |
| Equipment Group | I | For use in underground mines |
| II | For use in all other places | |
| Category | 1 | Equipment that is intended for use in areas where an explosive atmosphere is present continuously, for long periods or frequently |
| 2 | Equipment that is intended for use in areas where an explosive atmosphere is likely to occur in normal operation and must ensure a high level of protection. | |
| 3 | Equipment that is intended for use in areas where an explosive atmosphere is unlikely to occur in normal operation and must ensure a normal level of protection. | |
| Gas / Dust | G | Equipment certified for use in flammable gases |
| D | Equipment certified for use where dust is present in the atmosphere | |
| Type of Protection* | d | Flameproof |
| Ia | Intrinsically Safe | |
| e | Increased safety | |
| Gas Group | I | Mines |
| II | Surface above ground industries | |
| Gas Sub Group | A | Less easily ignited gases e.g. propane |
| B | Easily ignited gases e.g ethylene | |
| C | Most easily ignited e.g. hydrogen or acetylene | |
| Temperature Classification Hazardous area apparatus is classified according to the maximum surface temperature produced under fault conditions at an ambient temperature of 40°C, or as otherwise specified. The standard classifications are as shown |
T1 | 450ºC |
| T2 | 300ºC | |
| T3 | 200ºC | |
| T4 | 135ºC | |
| T5 | 100ºC | |
| T6 | 85ºC |
* There are 8 methods of protection, for simplicity we have listed the 3 most commonly used.
Product marking example
An ATEX approved electrical product is marked with the following code:
|
II 2G Eexd IIB T4 |
From the breakdown of the code below it can be seen that the product is flameproof, suitable for use in zone 1 surface applications where gas group B gases may be present and the surface temperature of the product under fault conditions will not exceed 135 ºC.
| |
Explosion proof in accordance with ATEX |
| II | Equipment group: II surface industries. |
| 2 | Category: 2 equipment (suitable for use in Zone 1) |
| G | Gas / Dust: Suitable for atmospheres containing gas |
| E | European certificate in accordance with harmonised standards |
| Ex | Explosion-proof electrical equipment |
| d | Type of protection is ‘Flameproof enclosure’ |
| II | Gas Group II – surface industries |
| B | Gas sub group = B |
| T4 | Temperature class T4 |
Please note: This information is provided as current at time of publishing. We are not responsible for any use of it. Seek expert guidance prior to servicing, using or classifying any equipment that might be used in a potentially explosive atmosphere.