What are ATEX zones? Explanation of zones 0 to 22 according to the ATEX directive

When selecting explosion-proof equipment, the ATEX zone in which it will be used is crucial. But what exactly do these zones mean? In this blog, we explain the differences between zones 0, 1 and 2 (gas/vapour) and zones 20, 21 and 22 (dust) – so you can always make the right choice.

What is an ATEX zone?

An ATEX zone indicates how often and how long an explosive atmosphere can be present. The zones are divided into two categories:

• Gas/vapour/mist zones: zones 0, 1 and 2
• Dust zones: zones 20, 21 and 22

Both categories have their own risk profile and equipment requirements.

Gas and vapour zones

Zone 0

Definition: Explosive atmosphere (gas, vapour or mist) is present permanently or for long periods.

Examples: Inside storage tanks or pipes.

Requirements: Only equipment with the highest degree of protection is permitted.

Zone 1

Definition: Explosive atmosphere occurs regularly during normal use.

Examples: Edges of storage tanks, areas around pumps or valves.

Requirements: Equipment must be completely safe under normal use.

Zone 2

Definition: Explosive atmosphere occurs rarely and for short periods.

Examples: Areas around tanks or pipes where leakage occurs only occasionally.

Requirements: Equipment must not cause ignition under normal conditions or in the event of a single fault.

Dust zones

Zone 20

Definition: An explosive atmosphere caused by combustible dust in the form of a cloud is present continuously or for long periods.

Examples: Inside silos, mixing chambers or filters in which dust circulates permanently.

Requirements: Equipment must be suitable for continuous use in heavy dust loads, with maximum explosion protection.

Zone 21

Definition: An explosive dust atmosphere may form regularly during normal use.

Examples: Around filling stations, conveyor belts or processing installations.

Requirements: Equipment must be dust-tight and function safely under normal conditions.

Zone 22

Definition: Explosive dust atmospheres occur rarely and only briefly.

Examples: Storage rooms, corridors or maintenance areas where dust may escape occasionally.

Requirements: Equipment must offer protection against occasional exposure to combustible dust.

Whether it's gases or dust, the correct zone classification determines which ATEX-certified equipment you can safely use. Not sure about the right choice? Our specialists at Jenson ATEX Depot will be happy to help you.

Request free advice on ATEX equipment for your specific zone at [email protected].