Caput 6
Greges instrumentorum, categoriae et gradus tutelae
Editum
- How to read an Ex marking: decoding II 2 G Ex db IIC T4 Gb step by step
II 2 G Ex db IIC T4 Gb means group II, category 2, gas, flameproof level b, gas group IIC, 135 °C maximum surface temperature and EPL Gb. This guide decodes every element of ATEX and IEC markings, dust and old EEx markings, with worked examples.
- Equipment Protection Levels (EPL): Ga, Gb, Gc, Da, Db, Dc and how they match zones
EPLs rate how likely Ex equipment is to become an ignition source: Ga, Gb, Gc for gas, Da, Db, Dc for dust, Ma, Mb for mines. Learn the definitions, the default zone mapping, the link to ATEX categories and when risk assessment may change the EPL.
- ATEX equipment categories 1, 2 and 3 and how they relate to EPLs
ATEX categories M1, M2 and 1, 2, 3 (G or D) define how much protection equipment gives, which zones it may serve and which conformity assessment route applies. This guide explains each category, the notified body routes and the link to EPLs Ga to Dc.
- Equipment groups I, II and III: mining, gas and dust
Ex equipment is grouped by atmosphere: Group I for mines with firedamp, Group II for gases and vapours (IIA, IIB, IIC) and Group III for dusts (IIIA, IIIB, IIIC). Learn the definitions, MESG and dust criteria, why mines are separate and how ATEX groups differ.
- Ambient temperature range Ta: what -20 °C to +40 °C really means
Ex equipment is certified for an ambient range, by default -20 °C to +40 °C. Its temperature class and protection hold only inside it. How Ta is marked, what extended ranges require, and what it means for cable entries, cold climates and process heat.
- The X and U suffixes on Ex certificates: specific conditions of use and Ex components
An X after an Ex certificate number means specific conditions of use that the installer and user must meet; a U means an Ex component that cannot be used alone. Meaning, typical conditions, who is responsible, and what to do with each.