Type of explosion protection
| Code | Meaning | Applies to |
|---|
| Ex d | Flameproof | Gas (electrical) |
| Ex e | Increased safety | Gas (electrical) |
| Ex i | Intrinsic safety | Gas (electrical) |
| Ex m | Encapsulation | Gas (electrical) |
| Ex p | Overpressure | Gas (electrical) |
| Ex q | Powder filling | Gas (electrical) |
| Ex o | Liquid immersion | Gas (electrical) |
| Ex nA, nR, nC | Non-arcing, restricted breathing, enclosed construction | Gas (electrical) |
| Ex op is | Optical radiation | Gas (electrical) |
| Ex t / tD A2x | Protection by enclosure | Dust (electrical) |
| Ex p / pD | Overpressure | Dust (electrical) |
| Ex i / iD | Intrinsic safety | Dust (electrical) |
| Ex m / mD | Encapsulation | Dust (electrical) |
| b | Control of ignition source | Gas or dust (non-electrical) |
| c | Constructional safety | Gas or dust (non-electrical) |
| k | Liquid immersion | Gas or dust (non-electrical) |
| Ex h | Mechanical protection with b, c, or k | Gas or dust (non-electrical) |
| d | Flameproof | Gas or dust (non-electrical) |
Gas / dust group
| Group | Allowed in area with |
|---|
| IIA | IIA gases (e.g. methane, propane, acetone, kerosene, petrol) |
| IIB | IIA and IIB gases (e.g. ethyl glycol, ethylene, ethanol) |
| IIC | IIA, IIB, and IIC gases (e.g. hydrogen, acetylene) |
| IIIA | IIIA fibres (>0.5mm) |
| IIIB | IIIA and IIIB dust (non-conducting, <0.5mm) |
| IIIC | IIIA, IIIB, and IIIC dust (conducting, <0.5mm) |
Temperature class
| Class | Max surface temp | Allowed in area with |
|---|
| T1 | 450°C | T1 |
| T2 | 300°C | T1, T2 |
| T3 | 200°C | T1, T2, T3 |
| T4 | 135°C | T1, T2, T3, T4 |
| T5 | 100°C | T1, T2, T3, T4, T5 |
| T6 | 85°C | T1, T2, T3, T4, T5, T6 |
Hand tools (EN 1127-1, Annex A)
| Zone | Single sparks (hand tools) | Shower of sparks (sawing, grinding) |
|---|
| 0 / 20 | Not allowed | Not allowed |
| 1 | Limited allowed *1 | Not allowed |
| 2 | Allowed | Not allowed |
| 21 / 22 | Allowed | Limited allowed *2 |
*1 Steel tools not allowed with gas group IIC, H₂S, CO, or ethylene oxide.
*2 Protect the workplace and remove accumulated dust, or keep the workplace wet.
Clothing (CLC/TR 60079-32-1, 11.5)
| Zone | Requirement |
|---|
| All zones | Antistatic shoes (consider the surface); don't put clothes on or off in the area |
| Zone 0 and 1 | Anti-static clothing |
| Zone 2, 20, 21, 22 | No special requirements, except for very sensitive gases or dusts |
ATEX 114 — directive for manufacturers of equipment, safety devices, and protective systems.
ATEX 153 — directive for employers/end-users, covering safety and health protection of workers.
Sequence of measures
- Prevent the explosive atmosphere — remove fuel or oxygen
- Prevent ignition sources — ATEX equipment, spark-free tools, etc.
- Limit consequences — pressure relief, isolation, suppression
The explosion triangle: an explosive atmosphere needs explosive material, oxygen, and a source of ignition together. Remove any one and there's no explosion risk — this is why the sequence above starts with prevention rather than protection.