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DSEAR — Hazardous-Area Classification ​

Classify explosive-atmosphere zones (0/1/2) from substance properties, grade of release and ventilation, and derive the ATEX equipment category, gas group and temperature class — IEC 60079-10-1 / DSEAR 2002.

Overview ​

DSEAR (Dangerous Substances and Explosive Atmospheres) classification determines the hazardous zone around a source of flammable release and the ATEX equipment category, gas group and temperature class required for equipment installed there. ErgoPlanner implements the IEC 60079-10-1 logic as real conditional physics — not a flat lookup table: it applies a flashpoint flammability gate, maps grade of release to a base zone, then modulates that zone with the degree and availability of ventilation, and finally derives the equipment requirements with a written rationale.

In this guide you'll learn

  • How to create a DSEAR assessment and select a dangerous substance
  • How grade of release and ventilation drive the hazardous zone
  • How the zone maps to ATEX category, gas group and temperature class
  • How to read the classification rationale and save the assessment

Estimated Time: 20 minutes Difficulty: Intermediate

Prerequisites ​

  • A signed-in account
  • An engineering calculations entitlement — DSEAR gates the substance catalog and the classifier
  • Process and ambient temperatures for the location, and the grade/ventilation of the release source
  • Familiarity with IEC 60079-10-1 area-classification concepts

Where to find it ​

The assessment list is at /dsear/assessments; an individual assessment opens at /dsear/assessments/{id}.

How the classification works ​

The classifier proceeds in stages:

  1. Flammability gate — Using the substance flashpoint, process and ambient temperatures and the handled above flashpoint flag, it first decides whether a flammable atmosphere can form at all. If the liquid is handled well below its flashpoint and cannot form a flammable mist/vapour, the area may be non-hazardous.

  2. Grade of release → base zone — Per IEC 60079-10-1 Clause 5.3:

    Grade of releaseBase zone (gas)
    ContinuousZone 0
    PrimaryZone 1
    SecondaryZone 2

  3. Ventilation modulation — The degree (High / Medium / Low) and availability (Good / Fair / Poor) of ventilation adjust the base zone: high-degree, good-availability ventilation can reduce the zone (or its extent), while poor ventilation can make it more onerous.

  4. Equipment requirements — From the resulting zone the classifier derives:

    • ATEX equipment category — Category 1G (Zone 0), Category 2G (Zone 1) or Category 3G (Zone 2).
    • Gas group — IIA, IIB or IIC, from the substance.
    • Temperature class — T1–T6, from the substance autoignition temperature versus equipment surface limits.
    • A rationale explaining how the zone and category were reached.

Workflow ​

Step 1 — Create the assessment ​

  1. Go to /dsear/assessments and click Create Assessment.
  2. Enter an assessment name and optional description, and nominate a lead engineer.
  3. The assessment then asks for the release scenario (Step 2). Assessments progress through Draft → In Progress → Approved → Closed.

Step 2 — Describe the release scenario ​

Complete the scenario fields:

  • Substance — pick a dangerous substance from the catalog (the dropdown shows the substance and, where known, its flashpoint). The catalog provides each substance's flashpoint, LEL/UEL, vapour density, autoignition temperature and gas group.
  • Release grade — Continuous, Primary or Secondary.
  • Ventilation degree — High, Medium or Low.
  • Ventilation availability — Good, Fair or Poor.
  • Process temperature (°C) and Ambient temperature (°C).
  • Handled above flashpoint — a switch indicating whether the substance is processed above its flashpoint (which makes a flammable atmosphere far more likely).

Step 3 — Classify ​

Run the classification (the classifier is stateless, so you can iterate on inputs freely). The result panel shows:

  • Zone — Zone 0, Zone 1, Zone 2, or Non-hazardous.
  • ATEX category — Category 1G / 2G / 3G (or none).
  • Gas group — IIA / IIB / IIC.
  • Temperature class — T1–T6.
  • Rationale — the written explanation of the classification.

Step 4 — Save the assessment ​

Save to persist the scenario inputs and the computed classification as a named assessment for the safety file. You can re-open and update it later, and the stored result travels with it.

Worked example ​

A solvent with a flashpoint of 12 °C handled at a process temperature of 25 °C (i.e. above its flashpoint) with a Secondary grade of release and Medium / Good ventilation:

  • The flammability gate passes (handled above flashpoint).
  • Secondary release → base Zone 2.
  • Medium-degree, good-availability ventilation keeps it at Zone 2.
  • Result: Zone 2, ATEX Category 3G, with the substance's gas group (e.g. IIA) and temperature class derived from its autoignition temperature.

Use cases ​

  • Area classification drawings — Classify each release source on a plant and assign the zones that drive the hazardous-area drawing and equipment schedule.
  • Equipment selection — Use the ATEX category, gas group and temperature class to specify compliant motors, instruments and luminaires for each zone.
  • What-if on ventilation — Test whether improving ventilation degree/availability reduces a Zone 1 to Zone 2, lowering equipment cost, before committing to HVAC changes.

References ​

  1. IEC 60079-10-1 — Explosive atmospheres: Classification of areas (explosive gas atmospheres)
  2. IEC 60079-0 — Explosive atmospheres: Equipment — General requirements (gas groups, temperature classes)
  3. DSEAR 2002 — Dangerous Substances and Explosive Atmospheres Regulations
  4. Directive 2014/34/EU (ATEX) — Equipment for use in potentially explosive atmospheres