Ex Marking Decoder (ATEX and IECEx)
Paste the explosion protection marking from an instrument label or certificate to see what every part means and which hazardous area zones it may be used in.
Marking breakdown
| Element | Meaning |
|---|---|
| II 2G | ATEX equipment group II (surface), category 2 gas: suitable for zone 1 |
| Ex | Explosion protected equipment (IEC 60079 / EN 60079) |
| db | Flameproof enclosure (Ex d) |
| IIC | Gas group IIC (hydrogen, acetylene); suitable for IIA and IIB too |
| T4 | Temperature class T4: maximum surface temperature 135 °C |
| Gb | Equipment protection level Gb: Gas, high protection |
Anatomy of an Ex Marking
ATEX group and category · protection type · gas group · temperature class · equipment protection level
| Element | Options |
|---|---|
| Protection type | d flameproof, e increased safety, i intrinsic safety, m encapsulation, p pressurized, q powder, o liquid immersion, n type n, t dust enclosure |
| Gas group | IIA (propane) < IIB (ethylene) < IIC (hydrogen, acetylene); IIC covers all |
| Dust group | IIIA flyings < IIIB non conductive dust < IIIC conductive dust |
| Temperature class | T1 450 °C, T2 300 °C, T3 200 °C, T4 135 °C, T5 100 °C, T6 85 °C |
| EPL | Ga/Gb/Gc for gas zones 0/1/2, Da/Db/Dc for dust zones 20/21/22 |
Worked example
Ex ia IIC T4 Ga: intrinsically safe with two fault tolerance, suitable for all gas groups and gases igniting above 135 °C, and allowed in zone 0, 1 and 2.
Frequently Asked Questions
What does Ex db IIC T4 Gb mean?
A flameproof enclosure (db), for all gas groups including hydrogen (IIC), with a maximum surface temperature of 135 °C (T4), at equipment protection level Gb, which allows zone 1 and zone 2.
What is the difference between ATEX and IECEx?
ATEX is the European legal requirement with CE marking and categories; IECEx is an international certification scheme. Both use the same IEC 60079 protection concepts and markings.
What does the X at the end of a certificate number mean?
There are special conditions for safe use, such as cable entry or ambient limits, that must be read in the certificate.
Learn more on the blog
Hazardous area classification zones
A practical, field focused guide on instrumentationblog.in that explains the theory behind this tool and how engineers apply it on real plants.
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