How to read an Ex marking on any device
Breaking down a marking like Ex db eb IIC T4 Gb piece by piece, and which zones the device is fit for.
The example
II 2G Ex db eb IIC T4 Gb
Part | Meaning |
|---|---|
II 2G | ATEX: equipment group II (non-mining), category 2, gas |
Ex | explosion-protected equipment |
db | flameproof enclosure |
eb | increased safety for terminals and connections |
IIC | fit for the most severe gas group: hydrogen, acetylene |
T4 | maximum surface temperature 135°C |
Gb | high protection level: Zone 1 and Zone 2 |
The golden rule
- The zone sets the EPL: Zone 0 needs Ga, Zone 1 needs Gb or better, Zone 2 needs Gc or better.
- The gas sets the group and temperature class: an IIC device also covers IIB and IIA; a T4 device suits gases whose auto-ignition temperature is above 135°C.
Note
This is educational. Final selection depends on the area classification study, the device certificate and IEC 60079. Try the Ex decoder in the workshop.