What are ex-zones?
"Explosive atmospheres" are not equally dangerous everywhere. They are therefore divided into so-called zones. These indicate how often and for how long an explosive atmosphere can occur in an area.
A basic distinction is made between two types of zones:
- Gas Ex areas → for gases, vapors or mists
- Dust Ex zones → for combustible dusts (e.g. flour, plastic powder, metal dust)
🧯 Zoning at a glance
Gas Ex areas:
| Zone | Meaning | Example |
|---|---|---|
| Zone 0 | Constantly or frequently occurring explosive atmosphere | In tanks, reactors |
| Zone 1 | Occasionally available | Proximity to vents, filling systems |
| Zone 2 | Only rarely or briefly available | Surroundings of zone 1, e.g. leakage areas |
Dust-free zones:
| Zone | Meaning | Example |
|---|---|---|
| Zone 20 | Constant or frequent dust cloud | Interior of silos, mills |
| Zone 21 | Occasional dust in the air | Petrol stations, under silos |
| Zone 22 | Short-term dust dispersion | Areas under conveyor belts, maintenance flaps |
🛠️ What can be used where?
Depending on the zone, different requirements apply to equipment, machines, tools and systems.
Electrical devices (e.g. sensors, drives, lights):
| Device category | Use in the zone | Examination by notified body |
|---|---|---|
| Category 1 | Sounds 0 / 20 | ✔️ Mandatory: EU type examination (module B) + production control (module D or F) |
| Category 2 | Zone 1 / 21 | ✔️ Mandatory: EU type examination (module B) + module C1 or F |
| Category 3 | Zone 2 / 22 | ❌ No notified body - self-certification by the manufacturer (Module A) |
Non-electrical (mechanical) devices (e.g. tools, pumps, drives):
| Device category | Use in the zone | Examination by notified body |
|---|---|---|
| Category 1 | Sounds 0 / 20 | ✔️ Obligation: Type examination and quality assurance (e.g. module B + D) |
| Category 2 | Zone 1 / 21 | ❌ Not mandatory, but possible on a voluntary basis - personal responsibility with technical documentation |
| Category 3 | Zone 2 / 22 | ❌ No notified body - only internal assessment and declaration of conformity |
Important: The higher the hazard (i.e. the lower the number of zones), the stricter the requirements for the device or tool! For electrical devices, a notified body must always be consulted for categories 1 and 2. For non-electrical devices (e.g. compressed air machines), this is only mandatory for category 1 - a manufacturer's assessment with technical documentation is sufficient for zone 1.
⚠️ Practical example: Leaking valve
A gas leak in a piping system causes vapors to escape regularly in a small area. Although the leak is small, an explosive atmosphere is regularly created there - it is therefore zone 1.
Only a category 2G device with the appropriate labeling may be used here - anything else would be a violation of the safety regulations.
📋 How to recognize suitable devices:
Observe the marking on the rating plate, e.g:
II 2G Ex db IIC T4 Gb
This means:
- II = Not underground (mining)
- 2G = Permitted for zone 1 (G = gas, 2 = occasional)
- Ex db = Explosion protection through flameproof enclosure
- T4 = Max. Surface temperature 135 °C
🧯 Fazit
Zones define the risk - device categories define the requirements
.
Everyone who works in potentially explosive atmospheres should be aware of this:
- Which zone are you in?
- Which device category is permitted there?
- Whether the device used has a valid ATEX marking