When specifying an ATEX explosion proof container for a hazardous area installation, the most common — and most costly — mistake is getting the zone classification wrong. Over-specifying Zone 1 equipment for a Zone 2 location wastes budget. Under-specifying creates a serious safety and compliance risk. This guide explains the difference between Zone 1 and Zone 2, how to determine the correct classification for your site, and what it means for your container specification.
What Is ATEX and Why Does It Matter?
ATEX is the EU directive governing equipment used in explosive atmospheres — environments where flammable gases, vapours, mists or dusts may be present. The equivalent international standard is IECEx, recognised globally outside the EU.
Any electrical or mechanical equipment installed in a classified hazardous area — including containers housing electrical systems, compressors, generators or control panels — must be certified to the appropriate ATEX or IECEx category.
Non-compliant equipment in a classified zone is a serious regulatory violation and creates significant liability in the event of an incident.
ATEX Zone Classification: Gas and Vapour Atmospheres
Zone 0
An area where an explosive atmosphere in the form of a cloud of flammable gas, vapour or mist is present continuously or for long periods. Very rare in practice — typically only inside storage tanks or process vessels. Container installations in Zone 0 are exceptional and require the highest level of equipment protection.
Zone 1
An area where an explosive atmosphere is likely to occur in normal operation occasionally. Examples include areas near open process equipment, pump seals, flanged connections and ventilation outlets on offshore platforms. Zone 1 requires Category 2 equipment — higher cost, more stringent certification.
Zone 2
An area where an explosive atmosphere is not likely to occur in normal operation, and if it does occur, will exist only for a short time. The most common classification for container installations near process areas. Zone 2 permits Category 3 equipment — less costly than Zone 1 but still requires full ATEX certification.
ATEX Zone Classification: Dust Atmospheres
- Zone 20 — explosive dust atmosphere present continuously (equivalent to Zone 0)
- Zone 21 — explosive dust atmosphere likely in normal operation (equivalent to Zone 1)
- Zone 22 — explosive dust atmosphere unlikely in normal operation (equivalent to Zone 2)
Dust classifications are common in grain handling, pharmaceutical manufacturing, mining and wood processing. Container installations in these environments require specific dust-rated ATEX equipment.
How to Determine Your Site’s Zone Classification
Zone classification is the responsibility of the site operator and must be documented in a formal Hazardous Area Classification (HAC) study. This study identifies all potential sources of ignition release, defines the zone boundaries and specifies the required equipment protection level.
For container procurement, always request the HAC study or zone drawing from the site operator before specifying equipment. Never assume the zone classification — it must be confirmed in writing.
What Zone Classification Means for Your Container Specification
Zone 1 Container Requirements
- All electrical equipment: Category 2G (gas) or Category 2D (dust)
- Explosion-proof (Ex d) or intrinsically safe (Ex i) electrical installations
- Non-sparking materials for mechanical components
- Flame arrestors on all ventilation openings
- Static grounding and bonding connections
- Full ATEX certification documentation for all installed equipment
Zone 2 Container Requirements
- All electrical equipment: Category 3G (gas) or Category 3D (dust)
- Increased safety (Ex e) or non-sparking (Ex n) electrical installations permitted
- Flame arrestors on ventilation openings
- Static grounding connections
- Full ATEX certification documentation for all installed equipment
Common Applications by Zone
Typical Zone 1 Installations
- Offshore platform process decks
- Pump rooms and compressor houses
- Flammable liquid loading and unloading areas
- Areas adjacent to relief valve outlets
Typical Zone 2 Installations
- Offshore platform non-process areas
- Onshore refinery perimeter areas
- Chemical plant storage areas
- Fuel storage compound perimeters
Tamga Modules ATEX Explosion Proof Container Solutions
Tamga Modules manufactures ATEX certified explosion proof containers for Zone 1 and Zone 2 hazardous area installations. Our units are fully certified to the ATEX Directive 2014/34/EU and IECEx standards, with complete documentation packages for regulatory compliance.
We supply explosion proof containers for oil and gas, chemical, pharmaceutical, mining and defence applications across Europe, the Middle East and Africa. We also supply ATEX certified compressor containers and E-House containers for hazardous area power distribution.
ATEX Container Certification: Step-by-Step Process
Understanding the certification process helps procurement teams set realistic timelines and avoid costly delays. Here is how ATEX container certification works in practice:
Step 1: Hazardous Area Classification Study
Before any equipment is specified, the site operator must provide a formal Hazardous Area Classification (HAC) study or zone drawing. This document defines the zone boundaries, the gas or dust group, and the temperature class. Without this document, no ATEX specification can be written. Allow 2-4 weeks for this study if it does not already exist.
Step 2: Equipment Selection and Specification
Based on the HAC study, all electrical equipment inside the container is specified to the appropriate ATEX category and protection concept. Zone 1 typically requires Ex d (flameproof) or Ex e (increased safety) equipment. Zone 2 permits Ex n (non-sparking) equipment. Every component — from lighting to cable glands — must be individually certified.
Step 3: Design Review and Documentation
A complete equipment schedule listing every ATEX certified component, its certificate number and its protection concept is prepared. This document forms the basis of the ATEX technical file required by the directive.
Step 4: Factory Build and Inspection
The container is built to the approved design. A third-party inspection body — typically a Notified Body under the ATEX Directive — inspects the installation, verifies component certificates and checks the wiring and earthing systems.
Step 5: Declaration of Conformity
On successful inspection, the manufacturer issues an EU Declaration of Conformity and affixes the CE and Ex markings to the container. The complete technical file is handed over to the client for their regulatory records.
Typical Certification Timeline
| Stage | Typical Duration |
|---|---|
| HAC study (if required) | 2–4 weeks |
| Design and specification | 1–2 weeks |
| Factory build | 4–8 weeks |
| Third-party inspection | 1–2 weeks |
| Documentation and delivery | 1 week |
| Total | 9–17 weeks from order |
Common ATEX Compliance Mistakes to Avoid
Mistake 1: Assuming the Zone Classification
Never assume the zone classification without a formal HAC study. A procurement team that specifies Zone 2 equipment for what turns out to be a Zone 1 location faces expensive rework and potential regulatory enforcement action. Always obtain written confirmation of the zone classification from the site operator before issuing a purchase order.
Mistake 2: Specifying the Container Without the Zone Classification
Some buyers issue container specifications before the HAC study is complete, then discover the zone classification requires more expensive equipment than budgeted. Build HAC study completion into your project programme before container specification begins.
Mistake 3: Ignoring Cable Gland and Conduit Certification
ATEX certification applies to every component that could be a source of ignition — including cable glands, conduit fittings and junction boxes. A container with fully certified switchgear but non-certified cable glands is non-compliant. Verify that every penetration point is included in the equipment schedule.
Mistake 4: Missing the Earthing and Bonding Requirements
Static electricity is a significant ignition risk in hazardous areas. ATEX compliant containers require a dedicated earthing and bonding system — not just a connection to the site earth. Verify that the earthing design is included in the container specification and inspected as part of the certification process.
Mistake 5: Not Requesting the Full Technical File
The ATEX Directive requires the manufacturer to maintain a technical file for each certified product. Buyers should always request a copy of this file on delivery — it contains the equipment schedule, individual component certificates, wiring diagrams and the Declaration of Conformity. Without it, you cannot demonstrate compliance to an inspector or insurer.