ATEX - Decoded

👩🏽‍💻 Are you an engineer, safety auditor or process designer? Do you work with ATEX certified products? If so, this blog post is for you! 🧰


ATEX is a standard for products and services that are designed to be used in explosive environments. It is also known as the 'Explosive Atmospheres Directive'. ATEX certification is mandatory for any products that are used in these environments.


However, ATEX certification can be a confusing and complicated process. In this blog post, we will decode ATEX certification for you. We will explain what it is, why it is important and how you can get your products certified.


So, if you want to know everything there is to know about ATEX certification, read on!




What is an ATEX coding?

The ATEX code is an alphanumeric string that denotes the certification achieved by the product along with the environment and conditions it is suitable for.

The code can be broken down into a prefix, for example: CE0518 Ex II 2 G and suffix, for example: Ex d IIC T6 Gb.

Products may carry more than one suffix for the same prefix which allows definition of applicability for different environments, for example Gas and Dust hazards.

What does the ATEX prefix mean?

The prefix has 5 sections with the first part confirming that the product complies with the European Directive (CE) and the reference number for the notified body that produced the certification.

After this is the ATEX logo, shown as Ex within a hexagon.

The third section defines the Equipment Group and there are only 2 options for this, I or II where I relates to use in Mines where firedamp may be present and II becoming anywhere other than mines. The vast majority of labels in industrial applications are likely to be Equipment Group II.

The fourth part of the coding is the Equipment Category of which there are 5 variants, M1 & M2 for mine applications and 1, 2 or 3 for anything other than mining. As the number increases in size, the protection level falls such that the highest protection will always be 1 or M1. It is possible for some certifications to state more than one Equipment Category.

The final part of the suffix refers to the Environment which will be G for gases or vapours and D for combustible dusts.

Some devices may be dual certified for both Gas and Dust environments which means there will be a separate suffix for each to define the certification reached.

What does the ATEX suffix mean?

The ATEX suffix gets into the detail of how the device is protected from causing an explosion when installed in a hazardous area and what that hazard conditions are.

The ATEX suffix always starts with Ex to indicate Explosion Protection and is then followed by 4 more sections whether it is for Gas or Dust applications. Many devices may show a separate suffix for Gas and one for Dust because they have achieved testing and certification for both hazards.

Types of protection?

There are many different methods of preventing ignition in a hazardous environment and Types of Protection define which has been used in a particular case. After the initial Ex, will follow either one or two letters to indicate the type of Protection. Some require a second character to stipulate the level of protection and therefore which hazardous area Zone or Category they apply to.

The most common Types of Protection employed with valves and measuring instruments are d (Ex d), e (Ex e), m (Ex m), n (Ex n) and ia (Ex ia).

Types d, e and m are all suitable for Zones 1 or 2, Category 2 or 3 unless they have a second character of a, b, or c which further limits this. Note that types of protection can be combined and de, em or me are all commonly seen.

Ex d is commonly and incorrectly known as explosion proof but it actually is described as flameproof. This means that housing will contain a flame without allowing it to escape to the hazardous atmosphere.

Ex e means increased safety referring to the lack of arcs, sparks or hot surfaces.

Ex m is encapsulation that prevents the atmosphere reaching any potentially incendive parts.

Ex n is similar to Ex m and means non-sparking which limits it to Zone 2, Category 3 environments.

Ex ia or intrinsically safe is suitable for Zone 0 or 20, Category 1. This achieved through limiting the energy of sparks and surface temperatures through very low power requirements.


Gas or dust?

The next section of the coding refers to the Gas Group or Dust Type of the hazardous environment for which compliance has been certified.

I is solely for mining applications.

II covers all gas hazards and is shown as IIA, IIB , IIC or IID which relates to the potential gases that may be present where

A = Acetylene

B = Hydrogen

C = Ethylene

D = Propane

III indicates dust hazards and again is split into IIIA, IIIB and IIIC categories. IIA relates to combustible flying’s. IIIB is for non-conductive dusts and IIIC for conductive dusts.

In general, whether it is marked as II or III for the gas group, the C rating is always the safest as it relates to the biggest risk protection.

Temperature class?

The Temperature Class rating of T1, T2, T3, T4, T5 or T6 for gases, indicates the classification for the maximum surface temperature for the device and therefore the the distance to the potential ignition temperature for a particular gas.


Dust hazard classifications are shown as T followed by the maximum surface temperature in degrees Celsius.

Equipment protection level?

The Equipment Protection Level is the last part of the coding for Gas or Dust and is similar to the Equipment Category in that Ma and Mb are only related to mining.

Ga, Gb, Gc or Da, Db, Dc are the possible levels with Ga or Da being the highest protection.

Which Zone or Category?

Understanding whether a particular product can be employed in a certain area requires information on how the area and potential risk therein has been classified by the site or plant in question.

The Zones are decided by the site based on a risk assessment of the likelihood of a potentially explosive atmosphere being present.





Note that regardless of the risk assessment undertaken, it is always possible to use a higher rated Type of Protection that necessary for a particular Zone environment. For example, Ex ia could also be used in Zones 1 and 2 if required.


Example




This nameplate indicates the Notified Body reference for the certification is 0496, the Equipment Group is II (anywhere other than Mines), the Equipment Category is 1 or 2 and the environment is G and Dc where Dc equates to Zone 22 usage.

Ex d indicates flameproof Type of Protection, IIC is the Gas Group, T5 the Temperature Class and Gb the Equipment Protection level.

Ex t indicates a dust tight enclosure, IIIC is the Dust Type, IP67 ingress protection, Temperature Class is 100deg C and Equipment Protection Level Db for Zone 21.


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