The term ATEX comes from ATmosphères EXplosibles and refers to the European Union regulatory framework governing equipment intended for use in potentially explosive atmospheres.

ATEX certification is mainly based on Directive 2014/34/EU, which defines the essential health and safety requirements for equipment and protective systems intended for use in such environments. Understanding the meaning of ATEX certification is essential to ensure the safety of plants and operators across many industrial sectors.

ATEX regulations: definition and explanation of explosive atmospheres

An explosive atmosphere can occur when gases, vapours, mists, or combustible dusts mix with air under conditions that allow ignition. For this reason, pumps intended to operate in environments with explosion risk must be ATEX certified and designed to prevent the formation of ignition sources.

ATEX zones: what they are and why they are essential

Before selecting or installing an ATEX-certified pump, it is crucial to understand how hazardous areas within plants are classified. Zone classification makes it possible to assess how frequently and for how long a potentially explosive atmosphere may be present, and therefore to define the level of protection required for equipment such as pumps.

Zones are defined by mandatory regulations and are part of the ATEX framework relating to areas where gases, vapours, mists, or combustible dusts may be present.

ATEX zones for gases, vapours, and mists – explanation

• Zone 0: an area in which an explosive atmosphere is present continuously, frequently, or for long periods.
  These are the highest-risk areas and require Category 1 equipment.
• Zone 1: an area in which the formation of an explosive atmosphere is likely during normal operating conditions.
  Pumps installed in this zone must belong to categories offering a high level of protection.
• Zone 2: an area in which an explosive atmosphere is unlikely to occur and, if it does occur, will persist only for a short time.
  In this case, Category 3 equipment may be used, where permitted.

This classification derives directly from European definitions of potentially explosive atmospheres, where the presence of gases, vapours, or mists may lead to ignition phenomena under certain operating conditions.

ATEX equipment categories: meaning and definition

ATEX categories define the level of protection that equipment must guarantee when installed in areas with different probabilities of explosive atmospheres. This classification is established by ATEX Directive 2014/34/EU, which specifies the essential safety requirements and conformity assessment procedures to be applied before a product is placed on the European market.

The categories are directly related to ATEX zones: the higher the risk of an explosive atmosphere being present, the higher the level of protection required.

• Category 1 – Maximum Level of Protection

Equipment designed to operate in conditions of continuous, frequent, or prolonged risk, typical of Zones 0 (gas) or 20 (dust). These devices must ensure an extremely high level of protection, even in the event of a fault. They are required only for very critical applications where explosive atmospheres are almost constantly present.

• Category 2 – High Level of Protection

Designed for use in areas where an explosive atmosphere is likely under normal operating conditions, such as Zones 1 or 21. This equipment must remain safe even in the event of faults that can reasonably be expected to occur. In industrial practice, many ATEX-certified AODD pneumatic diaphragm pumps and piston pumps fall into this category, as they are often installed in chemical and pharmaceutical plants or in solvent and flammable fluid handling applications.

• Category 3 – Standard Level of Protection

Equipment suitable for zones where the presence of an explosive atmosphere is unlikely or, if it occurs, lasts only for a very short time (Zones 2 or 22). These devices are designed to ensure safety during normal operation, without the need for high fault tolerance. This category is used when the risk is low and well controlled.

ATEX marking

All equipment intended for use in ATEX zones must bear complete marking in accordance with Directive 2014/34/EU. Below is an example of ATEX marking:

1. CE: compliant with ATEX Directive 2014/34/EU.

2. ATEX: specific marking for explosion protection.

3. Equipment Group:
I - Equipment intended for use in underground mining operations and their surface installations, exposed to the risk of firedamp and/or combustible dust.
II - Equipment intended for use in other environments where explosive atmospheres may occur.

4. Category:
3G - Equipment suitable for use in Zone 2 where potentially explosive gases are present.
2G - Equipment suitable for use in Zone 1 and 2 where potentially explosive gases are present.
1G - Equipment suitable for use in Zone 0, 1 and 2 where potentially explosive gases are present.

5. Type of protection h: General protection for non-electrical equipment.

6. IIB - For all gases of Group IIA and IIB when the required level of protection applies (e.g. “ia”). See EN 60079-11.

7. Temperature class: T4 – Maximum permitted surface temperature 135°C.

8. EPL (Equipment Protection Level)
Ga - Protection level suitable for use in Zone 0.
Gb - Protection level suitable for use in Zone 1.
Gc - Protection level suitable for use in Zone 2.

ATEX summary