IECEx and ATEX describe general requirements for the construction, testing and marking of electrical equipment, components or devices intended for use in explosive atmospheres. Both IECEx and ATEX align with the same standards (e.g., IEC-EN 60079), so in terms of technical content, there is basically no difference.


More About IECEx

IECEx is an international system for certification of equipment for use in explosive atmospheres. Its quality assessment specifications are based on standards prepared by the International Electrotechnical Commission (IEC). The objective of these IECEx standards is to maintain the required level of safety while facilitating international trade in equipment and services for use in explosive atmospheres, by:

  • reducing manufacturers’ testing and certification costs, and time to market 
  • fostering international confidence in the product assessment process, and in the equipment/services covered by IECEx Certification 
  • providing one international database listing 


More About ATEX

The ATEX Directive covers equipment and protective systems intended for use in potentially explosive atmospheres. The Directive defines the essential health and safety requirements and conformity assessment procedures that must be applied before such products are placed on the EU market.


What Can Create an Explosion?

Explosion requires three contributing elements:

  1. Flammable substance in ignitable quantities (e.g., flammable dust/particulates or gases/mists)
  2. Oxygen (typically in the air)
  3. Ignition source (e.g., a spark, electrostatic discharge, open flames)


Where do you commonly find Ex equipment?   

Any industry/operation that manufactures, processes or uses materials that may be flammable. For example:

  • Automotive refueling stations 
  • Oil refineries, rigs and processing plants
  • Chemical processing plants
  • Printing industries (paper and textiles)
  • Aircraft refueling stations and hangars
  • Surface-coating industries
  • Sewage treatment plants
  • Gas pipelines and distribution centers
  • Grain handling and storage operations
  • Woodworking areas
  • Metal surface-grinding operations, especially aluminum dusts and particles

How IECEx / ATEX Define the Equipment Protection Level (EPL)

IECEx / ATEX standards use symbols and alphanumeric codes to classify different types of hazardous (explosive) conditions, and to define the likelihood of an explosion in those conditions.

Each piece of equipment or device that is certified as Explosion-Protected by IECEx / ATEX is assigned and labeled with a specific code.

The codes for GORE® PolyVent Ex+ are shown here:

ATEX symbols
  •         These symbols/letters stand for ex-rated equipment.
  • The rest of the code explains the equipment groups, categories, zones, protection levels and atmospheres in which a given device may safely be used, as well as type(s) of protection that device provides.


Equipment Protection Level (EPL)

EPL describes the level of protection a device provides. It’s based on assessing both the probability of a flammable atmosphere, and the risk of an ignition source forming on the device. According to IEC60079-0, devices for use in explosive atmospheres that contain flammable gases (G) or dusts (D), are classified into three protection levels: 

  • Ga or Da: “Very High” protection level, for zones 0 and 20
  • Gb or Db: “High” protection level, for zones 1 and 21
  • Gc or Dc: “Normal” protection level, for zones 2 and 22

EPL is an IEC designation which is similar to the ATEX Category & Zone designation, as shown in the GORE® PolyVent Ex+ example, below.


Understanding the Codes for GORE® PolyVent Ex+ (PMF200400)

ATEX symbols

Ex symbol
(according to ATEX directive)


Equipment Group
II = for all above-ground explosive environments


Equipment Category (Flammable Atmosphere)
2 = occassionally
3 = rarely, and for a short duraction
Category 2 devices may also be used in the areas that require category 3.

Corresponding Zones
2G = Zone 1 & 2
2D = Zone 21 & 22


Equipment Environment (Zone of Use)
G = Gases / Mists
D =  Dusts / Particulates


Type of Protection
eb = increased safety
tb = standard protection by housing


Atmosphere Group (II or III)
II = combustible gases / mists
C = requires the least energy to ignite (<20 µJ) – for example hydrogen
IIC is the highest possible rating, so it covers all other gas groups.

III = combustible dusts
C = conductive substances
IIIC is the highest possible rating, so it covers all other dust groups.


Equipment Protection Level (IECEx only)
Gb = “High” Protection Level, suitable in Zones 1 & 2
Db = “High” Protection Level, suitable in zones 21 & 22