EN 60079-0 is the base part of the series: it sets out the requirements common to all explosion-protected equipment, whatever the specific method of protection.
Temperature classes
The maximum surface temperature of the equipment must be lower than the ignition temperature of the gas present.
| Class | Max surface temperature |
|---|---|
| T1 | 450 °C |
| T2 | 300 °C |
| T3 | 200 °C |
| T4 | 135 °C |
| T5 | 100 °C |
| T6 | 85 °C |
Reading the marking
A typical ATEX marking reads II 2G Ex db IIB T4 Gb. Every element carries meaning — equipment group (II), category (2), medium (G for gas), type of protection (db), gas subgroup (IIB), temperature class (T4) and equipment protection level (Gb).
Non-metallic materials
The standard pays particular attention to plastic enclosures: the permitted surface area is limited, because static builds up on a large plastic surface. It is for the same reason that antistatic PPE is mandatory in ATEX zones.