An Ex marking is a short string of codes printed on every piece of explosion-protected equipment. It tells you which hazardous areas the equipment can go into. Our HZ7106 searchlights carry this one:
Ex db ia IIC T6 Gb
Read it left to right. Each part answers one question.
1. Ex: is it explosion protected?
The Ex prefix says the equipment was built and tested to the IEC 60079 series of standards for explosive atmospheres. Without it, the light must not enter a classified area.
2. Protection type: how is ignition prevented?
The next codes name the protection methods. A light can combine several.
| Code | Method | What it means |
|---|---|---|
| d / db | Flameproof enclosure | The housing can contain an internal explosion and stops flame escaping. |
| e / eb | Increased safety | Extra measures stop arcs, sparks and hot spots from occurring at all. |
| ia | Intrinsic safety, level a | Circuit energy stays too low to ignite gas even with two faults. |
| ib | Intrinsic safety, level b | As above, safe with one fault. |
| mb | Encapsulation | Parts that could spark are sealed in compound. |
| nR | Restricted breathing | The enclosure limits how much gas can get in. Zone 2 type of protection. |
Most small flashlights and headlamps use ib: the battery and LED driver are limited in energy. Larger searchlights add a flameproof body (db) because they hold more energy.
3. Gas group: which gases?
- IIA: propane and similar gases, the easiest to protect against.
- IIB: ethylene and similar.
- IIC: hydrogen and acetylene, the hardest to protect against.
A IIC light is also safe in IIA and IIB areas. Every Ex model in our range is rated IIC.
4. Temperature class: how hot can it get?
| Class | Max surface temperature |
|---|---|
| T1 | 450 °C |
| T2 | 300 °C |
| T3 | 200 °C |
| T4 | 135 °C |
| T5 | 100 °C |
| T6 | 85 °C |
The light's class must be lower than the auto-ignition temperature of the gas on site. T4 covers most hydrocarbons. T6 is the strictest class.
5. Equipment protection level: which zone?
- Ga: very high protection, for Zone 0, 1 and 2.
- Gb: high protection, for Zone 1 and 2.
- Gc: enhanced protection, for Zone 2 only.
Two examples from our range
HZ5130 headlamp, Ex ib IIC T4 Gb: intrinsically safe, any gas group, surface below 135 °C, for Zone 1 and 2.
HZ7625 flashlight, Ex d ib IIC T6 Gb: flameproof body plus intrinsically safe circuit, surface below 85 °C, for Zone 1 and 2.
Always match the marking to your site's hazardous area classification drawing, and keep a copy of the certificate with your equipment records.
