Hazardous Areas Explained: What ATEX Zones Mean for Your Equipment

In oil and gas plants, refineries, chemical stores, fuel areas, paint shops and on many vessels, flammable gas, vapour or dust can be present in the air. Ordinary electrical equipment can ignite it. That's why these areas need explosion-protected (Ex) equipment, certified under schemes such as ATEX (Europe) and IECEx (international).

Zones: how likely is an explosive atmosphere?

Gas and vapour

  • Zone 0: present continuously or for long periods.
  • Zone 1: likely to occur in normal operation.
  • Zone 2: not likely in normal operation, and only for a short time if it does occur.

Dust

  • Zone 20, 21, 22: the same idea for combustible dust, from continuous (20) to unlikely (22).

The zone is set by the site's hazardous area classification, usually done by the plant owner or a qualified engineer. Equipment must be certified for that zone or a stricter one.

Reading the Ex marking

The marking on Ex equipment tells you where it can be used. Key parts:

  • Protection type, for example "d" (flameproof enclosure), "e" (increased safety) or "i" (intrinsic safety).
  • Gas group (IIA, IIB, IIC) or dust group (IIIA, IIIB, IIIC). IIC and IIIC cover the most demanding gases and dusts.
  • Temperature class (T1 to T6). This is the maximum surface temperature. It must be below the ignition temperature of the gases present; T6 is the coolest.

What typically needs to be Ex-rated

  • Lighting: area lights, floodlights, emergency and exit lights.
  • Plugs, sockets, switches, junction boxes and control stations.
  • Portable equipment used inside the zone, such as torches and tools. Non-sparking hand tools may also be required.

Documents matter

Auditors and owners will ask for certificates. Keep the ATEX or IECEx certificate and datasheet for every item installed in a hazardous area. We supply these free of charge with Ex-rated products.

How Delight can help

Browse Explosion-Proof & Hazardous Area Fixtures and ATEX Plugs & Switches. Send us your zone, gas group and temperature class, and we'll match and quote certified equipment, with certificates, within 24 hours. We supply plants and vessels in Singapore and overseas. Request a quotation.

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