ATEX Marking Explained — Reading the Ex Label
The ATEX marking on Ex equipment contains all the information you need to verify it is appropriate for the area where it is installed. Being able to read and interpret an ATEX marking is a fundamental competency for anyone working in hazardous areas — and it is tested in CompEx assessments.
ATEX Marking Structure
A complete ATEX marking looks like this: ⑥ II 2 G Ex d IIB T4 Gb
| Element | Meaning | Example |
|---|---|---|
| ⑥ | ATEX hexagon symbol | Confirms ATEX certified |
| II | Equipment group — surface industries | Group I = mining only |
| 2 | Equipment category | 1=Zone 0, 2=Zone 1, 3=Zone 2 |
| G | G = gas atmosphere, D = dust | G for gas zones |
| Ex | Indicates Ex protection | Always present |
| d | Protection type | d=flameproof, e=increased safety, i=intrinsic safety |
| IIB | Gas group | IIA, IIB, or IIC |
| T4 | Temperature class | T1-T6, lower number = higher max temp |
| Gb | Equipment Protection Level | Ga=Zone 0, Gb=Zone 1, Gc=Zone 2 |
Worked Examples
⑥ II 2 G Ex e IIB T3 Gb
Group II surface industry, Category 2 (Zone 1), gas atmosphere, increased safety protection, IIB gas group, T3 temperature class (max 200°C), EPL Gb (Zone 1 suitable). This equipment can be installed in Zone 1 or Zone 2 IIB or IIA areas where the gas AIT exceeds 200°C.
⑥ II 1 G Ex ia IIC T5 Ga
Group II surface industry, Category 1 (Zone 0), gas atmosphere, intrinsic safety ia protection, IIC gas group (hydrogen/acetylene), T5 temperature class (max 100°C), EPL Ga (Zone 0 suitable). This is a Zone 0 IS instrument for IIC gas group applications.
When inspecting any Ex equipment, always verify the marking plate matches the area classification. The gas group on the plate must match or be rated higher than the area gas group. The EPL must be appropriate for the zone. The T-class must not exceed the gas AIT. Any mismatch is a deficiency — potentially Category X.
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