Understanding ATEX – What is it and what does it do?

Ever wondered what ATEX certified means? Ever tried to decipher something along the lines of: II 1G Ex ia IIC T4 Ga? Read our in-depth guide here:

What is ATEX?APEX logo

ATEX comes from the French ‘ATmosphères EXplosibles.’

It is the name commonly given to the two European Directives for controlling explosive atmospheres, ATEX Workplace Directive and ATEX Equipment Directive.

Explosive atmospheres can be caused by flammable gases, mists or vapours or by combustible dusts. If there is enough of the substance, mixed with air, the slightest source of ignition can cause an explosion.

Explosions can cause loss of life and serious injuries as well as significant damage.

What does ATEX equipment certification certify?

ATEX defines and certifies a range of Elements:

  • The device group:

I = can be used in mining
II = can be used in all other explosive areas (but not in mining)

  • A category that defines the zones the equipment can operate in.

Employers must classify areas where hazardous explosive atmospheres may occur       into zones. The classification differentiates between gas and dust-based fuels, the likelihood of an explosive atmosphere occurring and its persistence if it does:


  •  Which Atmosphere the equipment can be used in

G = Gas
D = Dust

  • Explosion Protection

Ex = ATEX certified

  • Ignition protection class:

What method the equipment uses to achieve safety. These include for example separation, special mechanical construction or limitation of energy.


o =    Equipment components are completely submerged in oil
q =    Equipment components are completely covered with a layer of Sand, powder or quartz
p =    Equipment is pressurised to a positive pressure relative to the surrounding atmosphere           with air or an inert gas, thus the surrounding ignitable atmosphere cannot come in contact with energized parts of the apparatus. The overpressure is monitored, maintained and controlled
ia =    intrinsic safety, The development of inadmissibly high temperatures, ignition sparks and arcs are avoided due to the restriction of energy in the circuit

  • Explosion Group (data only for devices used in areas rendered potentially explosive by gas). Group I needs the most amount of energy to ignite, group IIC the least, so equipment designed for use in e.g. gas group IIB is also safe to use in IIA.:


  • Temperature Class

The maximum surface temperature of a device must be less than the minimum ignition temperature of the atmosphere it is operating in. For this reason, the maximum surface temperature of equipment for use with inflammable gases, vapors or mists is specified in temperature classes. Here are the classes of the maximum permitted housing or component temperature of the operating devices:

T1 = 450°C
T2 = 300°C
T3 = 200°C
T4 = 135°C
T5 = 100°C
T6 = 85°C

  • Equipment Protection Level
Equipment Protection Levels (EPL’s) have been introduced to indicate the inherent ignition risk of equipment irrespective of the type of protection being used.

The EPL is defined by the intended use in the specified zones.


How to decipher the ATEX designation

Soo. What does the certification actually tell you? Here is an example:

Our partner HID Global have certified their Glass and IN Tags in the following way:


What does it mean?

Here is our breakdown:



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