{"id":1596,"date":"2026-07-08T07:59:28","date_gmt":"2026-07-08T07:59:28","guid":{"rendered":"https:\/\/climntech.com\/?p=1596"},"modified":"2026-07-17T08:02:45","modified_gmt":"2026-07-17T08:02:45","slug":"what-is-an-atex-zone-1","status":"publish","type":"post","link":"https:\/\/climntech.com\/en\/quest-ce-quune-zone-atex-1\/","title":{"rendered":"What is an ATEX Zone 1? Zone 2, Zone 21, Zone 22?"},"content":{"rendered":"

In many industrial sectors, certain workspaces present a permanent or occasional risk of explosion. These environments receive a precise regulatory classification: they are referred to as ATEX zones, an acronym for\u2019AT<\/strong>atmospheres EX<\/strong>Plosives. For any HSE manager, establishment manager, or maintenance manager, mastering this classification is a legal obligation. Just as understanding its concrete implications for equipping workstations is an operational necessity. ClimnTech provides an overview.<\/p>\n\n\n\n

What is an explosive atmosphere?<\/h2>\n\n\n\n

An explosive atmosphere forms when a mixture of flammable substances (in the form of gas, vapor, mist, or dust) combines with air in sufficient proportions to ignite in the presence of an ignition source. If the combustion spreads instantaneously throughout the entire mixture, it causes a sudden pressure increase: this is an explosion.<\/p>\n\n\n\n

The distinction between atmosphere explosive<\/em> and atmosphere Explosible<\/em> It is important. An explosive atmosphere is already present under ignition conditions. An explosive atmosphere is likely to become one depending on local conditions: pipe leakage, pipe rupture, thermal variation, machine startup.<\/p>\n\n\n\n

The sources of ignition that can trigger an explosion are numerous: electrical or electrostatic arcs, mechanical sparks, hot surfaces, and open flames. It is precisely this broad spectrum that necessitates strict regulations on all equipment deployed in these areas.<\/p>\n\n\n\n

The regulatory framework: two ATEX Directives<\/h2>\n\n\n\n

European regulation organizes responsibilities around two complementary directives.<\/p>\n\n\n\n

The Directive 2014\/34\/EU<\/strong> (formerly 94\/9\/EC) is aimed at equipment manufacturers. It requires CE marking for equipment used in ATEX zones and defines the safety categories that each piece of equipment must comply with according to the zone in which it will be deployed.<\/p>\n\n\n\n

The Directive 1999\/92\/EC<\/strong> It is addressed to employers. It obliges them to assess explosion risks in their facilities, to delineate ATEX zones, and to formalize this analysis in an Explosion Protection Document (DRPCE). This document must demonstrate that the risks have been assessed, that the measures taken meet the directive's requirements, and that the equipment used is compliant with the zone in which it operates. The zoning itself is carried out under the responsibility of the site manager.<\/p>\n\n\n\n

ATEX Zones Classification: Gases and Dusts<\/h2>\n\n\n\n

ATEX zoning classifies areas based on the probable frequency and duration of an explosive atmosphere's presence. Two families of risks coexist: gas\/vapor\/mist atmospheres (Zone G) and dust atmospheres (Zone D).<\/p>\n\n\n\n

Gas zones (G)<\/h3>\n\n\n\n

Zone 0<\/strong> The explosive atmosphere is present permanently or for very long periods (more than 1,000 hours per year). Typical example: the inside of a tank containing a flammable liquid. Equipment deployed here must belong to Category 1G, the highest safety level.<\/p>\n\n\n\n

Zone 1<\/strong> Explosive atmospheres are likely to occur occasionally during normal operation, between 10 and 1,000 hours per year. Examples: immediate vicinity of a valve or flange on a flammable product pipeline, area around a hydrocarbon storage vent. Required equipment is category 2G.<\/p>\n\n\n\n

Zone 2<\/strong> : An explosive atmosphere is unlikely during normal operation and, if it occurs, it only lasts for a short time (less than 10 hours per year). Examples: peripheral areas to Zone 1, ventilated rooms containing hazardous installations. Category 3G equipment is sufficient.<\/p>\n\n\n\n

Dust zones (D)<\/h3>\n\n\n\n

Zone 20<\/strong> permanent or prolonged presence of flammable dust clouds. Required equipment category: 1D.<\/p>\n\n\n\n

Zone 21<\/strong> Occasional release of dust clouds during normal operation. Required Category: 2D. Affected sectors: flour mills, grain silos, sugar industries, wood processing, pharmaceuticals.<\/p>\n\n\n\n

Zone 22<\/strong> : unlikely and short-lived presence of suspended dust. Required category: 3D.<\/p>\n\n\n\n

A technical point to remember about dust: the visible presence of deposits already indicates a probability of a hazardous area. From 50 grams of dust per square meter (or 0.3 mm thick), the conditions for an explosion are met if this deposit is suspended in the presence of a sufficiently powerful ignition source.<\/p>\n\n\n\n

Temperature class: a decisive parameter<\/h2>\n\n\n\n

Each piece of equipment deployed in an ATEX zone carries a temperature class, noted T1 to T6, which indicates the maximum surface temperature the device can reach. This value must remain below the auto-ignition temperature of the gas or dust present in the zone.<\/p>\n\n\n\n

For example, ethylene ignites spontaneously at 425 \u00b0C (T2 class), while certain organic dusts have much lower auto-ignition temperatures. Equipment classified as T4 does not exceed 135 \u00b0C on its surface. This covers the vast majority of common industrial environments.<\/p>\n\n\n\n

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Are you managing an ATEX-certified site and looking for compliant thermal comfort solutions? Contact ClimnTech experts for advice tailored to your area<\/a><\/strong><\/p>\n<\/blockquote>\n\n\n\n

Read the ATEX equipment marking<\/h2>\n\n\n\n

Any device certified for ATEX zones bears a standardized marking that summarizes all of its safety features. Let's take the marking for ClimnTech coolers: II 2G IIB T4 Gb.<\/p>\n\n\n\n

This marking is deciphered as follows:<\/p>\n\n\n\n