How to Read an ATEX Marking

When a distributor ingests fifty supplier feeds for hazardous-area equipment, the same flameproof junction box can arrive as II 2G Ex d IIC T6 from one vendor, Ex d IIC T6 Gb from a second, and a plain-text blob like ATEX Zone 1, flameproof, T6 from a third. To a naive catalog system these look like three different products. To a buyer specifying equipment for a Zone 1 gas area, all three must resolve to the same canonical record — with a single, validated ATEX string. That gap between raw supplier text and a trusted, searchable attribute is exactly the problem Claro solves: it parses the marking into structured fields, validates each field for internal consistency, matches the result to your existing golden records, and writes clean attributes back into your PIM or ERP.

Anatomy of an ATEX marking

An ATEX marking is the standardized string stamped on equipment intended for explosive atmospheres. It follows a fixed left-to-right order defined by the ATEX directive and the IEC/EN 60079 series.

First block — equipment group and category

The first element is the equipment group:

• Group I — mining (firedamp and coal dust)
• Group II — surface industries (all other explosive atmospheres)
• Group III — dust-specific surface applications (in some newer markings)

Immediately after the group comes the category (1, 2, or 3). Category 1 is the highest level of protection; it is required for Zone 0 (gas) or Zone 20 (dust) locations where an explosive atmosphere is present continuously or for long periods. Category 2 covers Zone 1 / Zone 21; category 3 covers Zone 2 / Zone 22.

A capital G (gas) or D (dust) follows the category. So II 2 G is a surface-industry, category 2, gas product.

Second block — protection method and gas/dust group

After the Ex hexagon comes the protection-type code, which specifies how the equipment achieves safety:

The protection type is followed by the gas group (IIA, IIB, or IIC) for gas apparatus, or the dust group (IIIA, IIIB, IIIC) for dust apparatus. IIC is the most stringent gas group, covering hydrogen and acetylene atmospheres; IIA covers propane and similar gases.

Third block — temperature class

The temperature class (T1 through T6) is the maximum surface temperature the equipment may reach. It must remain below the auto-ignition temperature of the surrounding gas or vapour:

Optional suffix — Equipment Protection Level (EPL)

More recent markings include an EPL suffix such as Ga, Gb, Gc (gas) or Da, Db, Dc (dust). This maps closely to the category but is defined at the equipment level rather than for the installation zone. Gb is roughly equivalent to category 2 in a gas atmosphere.

A fully qualified modern marking therefore reads: Ex d IIC T4 Gb — flameproof, hydrogen-rated, 135 C maximum surface temperature, zone 1 gas protection level.

Why ATEX data almost never arrives clean

For distributors and marketplaces, ATEX attributes are among the highest-stakes fields in the catalog. A mismatch is not a formatting error; it is a safety and liability one. The problem is that clean data is the exception:

• Spacing and ordering differ between suppliers (some write II2G, others write II 2 G)
• The EPL suffix (Gb, Db) is present in some feeds and absent in others for the same product
• Older certificates use category notation; newer ones use EPL notation
• Some suppliers send a free-text description in place of a structured code
• Identical products carry different temperature class representations (T4 vs 135°C max)

Until the string is parsed into discrete, normalized fields — group, category, protection type, gas group, temperature class, EPL — catalog logic treats formatting variants as separate products. Deduplication fails. Faceted search returns incomplete results. AI assistants cannot match a buyer’s zone specification to the right SKU.

BEFORE / AFTER: raw supplier feed vs. trusted catalog record

Claro ingests the raw string from each supplier feed, parses it into the six structural fields above, runs a consistency check against the ATEX rules, and then matches the result against your existing catalog. Records that differ only in marking format are resolved to the same golden product. The normalized attribute values are written back to the correct fields in your PIM or ERP — no manual re-keying, no accumulation of variants, and no silent contradictions passed downstream.

How the blocks fit together: a worked example

Take the marking Ex d IIC T4 Gb:

1. Ex — the universal symbol for equipment built to IEC/EN 60079. Confirms the product carries formal explosion-protection certification.
2. d — flameproof enclosure. The housing can contain an internal ignition and prevent it from reaching the surrounding atmosphere.
3. IIC — the most stringent gas group. Suitable for hydrogen and acetylene environments, and therefore also valid for IIB and IIA atmospheres.
4. T4 — maximum surface temperature of 135 C. Safe for acetaldehyde and most common hydrocarbon atmospheres.
5. Gb — Equipment Protection Level b for gas. Equivalent to category 2; suitable for Zone 1 installations where an explosive atmosphere is likely to occur in normal operation.

Reading end to end: this is a flameproof device, rated for the most demanding gas groups, with a 135 C surface-temperature limit, suitable for Zone 1 gas installations. A specifier can match this directly against their site zone classification without reading a data sheet.

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