Knowledge / Ex protection
Every Ex device carries a standardised marking on its nameplate. This article breaks it down completely — from the equipment group to the special symbols “X”, “U” and square brackets.
The marking consists of two parts: the marking per Directive 2014/34/EU (Annex II No. 1.0.5) — Ex hexagon, equipment group, category, atmosphere — and the marking per standard (EN IEC 60079-0) with type of protection, group, temperature class and equipment protection level. Using the RW65_EX_II as an example:
The identical marking is also carried by the intrinsically safe LED beacon DKL01 — the system applies equally to every device type.
The letter after “Ex” names the type of protection — the design principle by which ignition is prevented. For gas atmospheres, the IEC/EN 60079 series defines, among others:
Enclosure withstands an internal explosion — motors, switchgear
Ignition sources avoided by design — terminal boxes, luminaires
Energy limitation in the circuit — instrumentation, sensors; “ia” as the only level down to Zone 0
Compound encloses ignition sources — solenoid valves, electronics
Protective gas under overpressure — cabinets, analysers
Ignition sources under oil — rare, e.g. transformers
Filling quenches sparks — rare, e.g. ballasts
Simplified requirements — Zone 2 only
Dust-tight enclosure with temperature limitation — dust hazardous areas
The group after the type of protection states which substances the device is suitable for. Higher groups include the lower ones — IIC therefore also covers IIB and IIA.
lowest ignition sensitivity
medium ignition sensitivity
highest ignition sensitivity — includes IIA and IIB
e.g. flour, wood dust
e.g. metal dust, soot — includes IIIA and IIIB
The temperature class limits the device's maximum surface temperature (EN IEC 60079-0, Clause 5.3.2, Table 2). It must stay below the ignition temperature of the gas present:
For dusts, direct maximum temperatures are usually stated instead of T classes. The permissible surface temperature must be checked against the ignition and glow temperature of the specific dust present (EN 60079-14).
ATEX category (Directive 2014/34/EU) and equipment protection level EPL (IEC 60079) describe the same protection level from two sets of rules. The assignment to zones is governed by EN 60079-14, Table 1:
Four additions are frequently overlooked in practice — and are legally relevant:
An “X” at the end of the certificate number (e.g. “…ATEX 1234X”) means: specific conditions of use apply, stated exclusively in the EU type examination certificate — for example requirements regarding ambient temperature, mounting or electrostatic charging. Compliant use is not possible without reading the certificate (EN IEC 60079-0).
A “U” identifies an incomplete Ex component (e.g. an empty enclosure) that only becomes usable equipment in combination with further components. Direct use in the zone is not permissible.
Square brackets, e.g. “II (1) G [Ex ia Ga] IIC”, identify associated apparatus: Zener barriers, isolating amplifiers or IS power supplies that are mounted in the safe area and whose circuits lead into the zone. The category in round brackets refers to the connected circuits.
If the permissible ambient temperature range deviates from the standard range of −20 °C to +40 °C, it must be stated on the nameplate, e.g. “−40 °C ≤ Ta ≤ +60 °C” (EN IEC 60079-0).
Intrinsically safe ATEX differential pressure gauge — Zones 0/1/2 and 20/21/22, ranges from 40 Pa.
View productIntrinsically safe 3-color LED beacon — Zones 0/1/2 and 20/21/22, IP67 fully potted.
View productSend us your zone, medium and task — we will check whether the RW65_EX_II or DKL01 with their approval (II 1 GD Ex ia IIC/IIIC T4 Ga Da) covers your requirement. We do not offer general ATEX consultancy; for applications using our devices, we provide concrete support.
Note: The content of this page is provided for general guidance and replaces neither the operator's risk assessment nor case-by-case verification by qualified personnel. Responsibility for sizing, equipment selection, installation and operation lies solely with the operator. Despite careful preparation, we accept no liability for accuracy or completeness; the currently valid edition of the applicable regulations and standards prevails.