In environments where highly combustible chemicals, gases, materials and liquids are handled, processed and produced, fire and explosion prevention are critical to occupational health and safety. In these conditions, even seemingly mundane substances could pose a risk.
An example of such would be dust and vapours. Though these are seemingly harmless and can sometimes go undetected, they are often highly combustible, specifically when ignition sources such as electronic devices are present within the operational environment. This is where intrinsically safe equipment is essential.
What is Intrinsic Safety (IS)?
Intrinsic safety (IS) is a protection technique for the safe operation of electrical equipment in hazardous areas by limiting the energy, electrical and thermal output available for ignition. In signal and control circuits that can operate with low currents and voltages, the intrinsic safety approach simplifies circuits and reduces installation cost over other protection methods.
Hazardous areas can be found where there is a possibility of an explosive combination of air, with the presence of flammable gases, dust, or a mixture of air, dust, and gases.
When electronic or electrical equipment of any type is intended for use in hazardous environments, the equipment must be ATEX and or IECEx certified as required by the EU directive 94/9/EC. Both ATEX and IECEx have multiple components but ATEX has only 3 Directives, whereas IECEx has 4 Schemes.
What is ATEX?
ATEX (from the French: ATmosphères EXplosibles) is a legal regulatory framework that is applicable within the European Union. It governs the manufacturing of all equipment intended for use in potentially explosive environments.
The ATEX Directive(s) mandate adherence to the Essential Health and Safety Requirements (EHSR). Consequently, meeting the applicable standards can fulfill these obligations.
Prior to ATEX, each European nation maintained its own regulations regarding equipment utilized in hazardous areas. This fragmentation created challenges for companies trying to comprehend and comply with the different requirements across the various regions. Consequently, there was a need for a global harmonizing standard that companies could follow, leading to the establishment of IECEx.
What is IECEx?
IECEx (International Electrotechnical Commission Explosive) is a voluntary certification program governed by the standards set by the International Electrotechnical Commission (IEC).
The objective of the IECEx System is to facilitate international trade in equipment and services for use in explosive atmospheres, maintaining the required safety level(s). Since IECEx is not a regulatory framework, but rather a standards-based scheme, it mandates full compliance with the IECEx standard listed on the IECEx Certificate.
Understanding ATEX & IECEx Certification Levels
The certification levels for ATEX and IECEx are based on the intended use of the equipment in different hazardous zones. These zones are categorized according to the probability of an explosive atmosphere occurring.
ATEX:
- EPL Ga/Gb/Gc for gas hazards
- EPL Da/Db/Dc for dust hazards
- EPL Ma/Mb for mining equipment
IECEx:
- EPM Ex ia/ib/ic for gas hazards
- EPM Ex ta/tb/tc for dust hazards
- EPM Ex Ma/Mb for mining equipment
The equipment is subsequently assigned an Equipment Protection Level (EPL) for ATEX or an Equipment Protection Method (EPM) for IECEx, reflecting the degree of protection it offers against potential ignition sources. Therefore, EPLs and EPMs exist for gas hazards, dust hazards, and mining equipment.
Understanding Zones
Both ATEX and IECEx classify hazardous areas into zones according to the probability and duration of a potentially explosive atmosphere’s presence. As illustrated in the table below, the zones for gases and vapours are quite comparable in both systems, whereas the zones for dusts exhibit slight differences:
| Zone | ATEX | IECEx |
| Gases & Vapour | ||
| 0 | An environment where an explosive atmosphere is consistently present. | An explosive atmosphere is consistently present or exists for extended durations. |
| 1 | An environment where an explosive atmosphere may occasionally arise. | An explosive atmosphere may develop during standard operations. |
| 2 | A location where an explosive atmosphere is unlikely to develop. | An explosive atmosphere is unlikely to arise during standard operations; however, if it does occur, it will only last for a brief period. |
| Dusts | ||
| 20 | An environment where an explosive atmosphere is consistently present. | An explosive atmosphere is consistently present or exists for extended durations. |
| 21 | An environment where an explosive atmosphere may occasionally arise. | An explosive atmosphere may develop during standard operations. |
| 22 | A location where an explosive atmosphere is unlikely to develop. | An explosive atmosphere is unlikely to arise during standard operations; however, if it does occur, it will only last for a brief period. |
Understanding Markings
As per ATEX directive, products are required to be marked with the CE mark and equipment coding as per the table below (There are 8 methods of protection, for simplicity, we have listed the 3 most commonly used):
| Heading | Mark | Application / Use(s) |
| Explosion proof | In compliance with the ATEX directive | |
| Equipment group | I | Intended for application in underground mines |
II | For use in all other environments | |
| Category | 1 | Equipment designed for operation in environments where explosive atmospheres are consistently present, either for extended durations or on a frequent basis. |
2 | Equipment designed for use in environments where an explosive atmosphere may arise during normal operations. Must guarantee an elevated level of protection. | |
3 | Equipment designed for operation in environments where an explosive atmosphere is unlikely to develop during regular use, Must provide a standard level of protection. | |
| Gas / Dust | G | Equipment approved for use in environments with flammable gases. |
D | Equipment approved for use in environments where dust is present in the atmosphere. | |
| Type of protection | d | Flameproof |
la | Intrinsically Safe | |
e | Increased Safety | |
| Gas group | I | Mines |
II | Surface above ground industries | |
A | Less easily ignited gases (e.g Propane) | |
B | Easily ignited gases (e.g Ethylene) | |
C | Most easily ignited (e.g Hydrogen) | |
| Temperature Classification* | T1 | 450 °C |
T2 | 300°C | |
T3 | 200°C | |
T4 | 135°C | |
T5 | 100°C | |
T6 | 85°C |
*Hazardous area equipment is categorized based on the maximum surface temperature it can reach under fault conditions at an ambient temperature of 40°C, or as specified otherwise.
Both certification(s) product markings include their certificate number; for ATEX this is the EU Type Examination Certificate number and for IECEx it is the Certificate of Conformity number.
To ensure optimum safety, equipment used in such environments must adhere to ATEX and IECEx certifications, which provide frameworks for safe operation by limiting ignition risks. Both ATEX and IECEx have played a significant role in harmonizing safety standards across various regions, simplifying the certification process for hazardous area equipment on a global level. Take a look at a selection of our intrinsically safe devices here.