Hazardous Area Classification
Done Right, the First Time
Accurate zone classification is the foundation of every ATEX compliance programme. Get it wrong and every equipment selection, inspection, and EPD built on top of it is compromised. Independent, field-verified zoning — for gas, vapour and dust.
(gas + dust combined)
EN 60079-10-1 & -10-2
across Europe
on every project
The Foundation of ATEX Compliance
Zone Classification Is Not a Document Exercise — It's an Engineering Decision
Hazardous area classification determines which zones exist, how large they are, and what category of Ex equipment is required. Every downstream decision depends on getting this right.
- Workplace Directive 1999/92/EC requires all explosive atmosphere areas to be classified into zones
- Zone classification must be based on release sources, ventilation, and substance properties — not assumptions
- Incorrect zoning leads to under-specified or over-specified equipment — both are non-compliant or wasteful
- Zone drawings must be kept up to date as the facility changes — they are living documents
- Zone classification forms the mandatory basis for the Explosion Protection Document (EPD)
- An independent classification by a competent engineer provides defensible, auditable results
Release source grade — Continuous, primary, or secondary release determines the zone category (0/1/2 for gas, 20/21/22 for dust).
Ventilation — Natural or forced ventilation directly shrinks or expands zone extents. Good ventilation can reduce Zone 1 to Zone 2 or eliminate a zone entirely.
Substance properties — Flash point, LEL, vapour density, and dust particle size all affect both the zone type and the required equipment temperature class and gas group.
Topography — Heavier-than-air vapours collect in pits and drains. Lighter-than-air gases accumulate in roof voids. The physical environment is part of the calculation.
Zone Categories
Understanding the Six Hazardous Zones
Gas/vapour and combustible dust are classified under separate zone numbering systems — both governed by EN/IEC 60079-10.
Gas & Vapour Zones (EN/IEC 60079-10-1)
Combustible Dust Zones (EN/IEC 60079-10-2)
What You Get
Classification Deliverables — What Each Document Does
A zone classification project produces a structured set of documents. Each one has a specific function in your compliance programme.
| Deliverable | Content | Used For |
|---|---|---|
| Release Source Register | All identified release sources, grade (continuous/primary/secondary), substance handled, release rate assumptions | Classification justification; audit baseline |
| Zone Drawings | Plan and elevation views with zone extents, zone type, equipment categories required, drawing revision history | EPD, equipment procurement, contractor briefing |
| Ventilation Assessment | Ventilation degree (high/medium/low), availability, effect on zone extents, recommendations for improvement | Zone extent justification; HVAC design review |
| Substance Data Summary | Flash point, LEL/UEL, vapour density, gas group (IIA/IIB/IIC), temperature class (T1–T6) for each substance | Equipment selection; Ex marking verification |
| Classification Report | Narrative justification for each zone decision, referencing EN 60079-10 methodology, signed and dated | EPD integration; regulatory authority; insurer |
| Equipment Category Matrix | Required equipment category per zone and substance combination — gas group and temperature class specified | Equipment procurement; Ex inspection input |
What Goes Wrong
The Most Common Zone Classification Failures
The Service
What a Classification Project Looks Like
From initial site review through to completed, EPD-ready documentation — a structured process that fits around your facility's schedule.
On-site walk-through to identify all potential release sources: valves, flanges, pumps, vents, filling points, drainage. Existing P&IDs and layout drawings reviewed in advance.
All substances handled assessed for flash point, LEL, vapour density, auto-ignition temperature. Gas group (IIA/IIB/IIC) and temperature class (T1–T6) determined per EN 60079-10.
Ventilation type, degree and availability assessed per EN 60079-10 methodology. Impact on zone extents calculated — and recommendations made where ventilation is insufficient.
Plan and elevation drawings produced showing all zone extents, zone types, and required equipment categories. Delivered in PDF and editable format for integration into your technical file.
Written narrative justifying every zone decision with reference to EN 60079-10 methodology. Signed and dated — ready for the EPD, auditors, and insurance assessors.
Existing classification reviewed against current plant layout and process. Gaps identified, drawings updated. Available as a one-off review or ongoing service for facilities under active modification.
Start with a free 30-minute online assessment. Describe your process and substances — and I'll tell you what classification scope you need and what it will cost.
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