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ATEX
ATEX Directive 2014/34/EU (previously 94/9/EU)
The ATEX directives define the EU’s minimum safety requirements for equipment used in explosive atmospheres. For industrial valves, pneumatic and electric actuators, and associated components, understanding these requirements is essential — from design and installation to maintenance and operation.
What Is ATEX?
ATEX stands for ATmosphères EXplosives and refers to two main EU directives:
ATEX 114 (2014/34/EU) – for manufacturers of equipment and protective systems used in potentially explosive atmospheres.
ATEX 153 (1999/92/EC) – for employers and operators, focusing on worker protection in environments where explosion risks exist.
The purpose is to ensure uniform safety standards across the EU and allow free trade of certified equipment. Equipment marked with CE and Ex symbols meets ATEX requirements and can be freely used within the European Union.
Zone Classification
Before selecting equipment, each area must be classified according to how likely an explosive atmosphere is to occur. Classification applies to both gases/vapors and dusts.
| Zone | Type | Description |
|---|---|---|
| 0 / 20 | Category 1 | Explosive atmosphere continuously or frequently present |
| 1 / 21 | Category 2 | Likely to occur occasionally during normal operation |
| 2 / 22 | Category 3 | Unlikely to occur or only for a short period |
Example:
A valve mounted near a flange connection with flammable gas inside might be in Zone 1 (2G), while a conveyor in a sugar plant might be Zone 21 (2D) due to combustible dust.
Structure of an ATEX Code – Example: II 2G Ex d IIB T6
| Code Element | Meaning |
|---|---|
| II | Surface industry (non-mining) |
| 2G | Zone 1, gas environment, Category 2 |
| Ex d | Protection method – flameproof enclosure |
| IIB | Gas group (medium explosivity) |
| T6 | Max surface temperature 85°C |
Protection Methods
A valve mounted near a flange connection with flammable gas inside might be in Zone 1 (2G), while a conveyor in a sugar plant might be Zone 21 (2D) due to combustible dust.
ATEX defines several protection principles for electrical and mechanical equipment:
Ex d – Flameproof enclosure: Any internal ignition is contained within the housing.
Ex e – Increased safety: Design minimizes ignition risks.
Ex i – Intrinsically safe: Electrical energy kept too low to ignite.
Ex t – Dust protection: Tight enclosures prevent dust ingress.
For valves and actuators, this means choosing the right materials, seals, and enclosure ratings (IP codes) to eliminate ignition sources.
Gas and Dust Groups
Different gases and dusts require different protection levels:
| Group | Type | Example | Hazard Level |
|---|---|---|---|
| IIA | Gas | Propane, Ammonia | Low |
| IIB | Gas | Ethylene | Medium |
| IIC | Gas | Hydrogen, Acetylene | High |
| IIIA | Dust | Wood dust | Low |
| IIIB | Dust | Plastic or sugar dust | Medium |
| IIIC | Dust | Metal dust (conductive) | High |
Temperature Classes
Equipment surface temperature must remain below the ignition temperature of the surrounding atmosphere.
For instance, a T6-rated solenoid valve must not exceed 85°C during operation.
| Class | Max Surface Temp | Typical Application |
|---|---|---|
| T1 | 450°C | General industrial areas |
| T2 | 300°C | Industrial environments with moderate ignition risk |
| T3 | 200°C | Oil/gas, chemical plants |
| T4 | 135°C | Refineries, fuel storage, solvent handling |
| T5 | 100°C | High-safety industrial zones with low ignition temperatures |
| T6 | 85°C | Maximum protection – high-risk gases |
Takeaway
In the valve and actuator industry, ATEX compliance begins with correct design and certification. All electrical and mechanical components — such as solenoids, limit switches, and positioners — must be approved for use in explosive atmospheres. Any potential ignition source, including metal-to-metal friction or static discharge, must be eliminated or strictly controlled to prevent explosion risk.
Manufacturers are required to document full compliance with the ATEX 114 directive and confirm that every product is suitable for its intended zone classification. Each valve or actuator must be delivered with an EU Type Examination Certificate, a technical file and user manual in the local language, CE and Ex markings, and clear information on temperature limits and zone ratings.
In daily operation, maintaining ATEX compliance relies on disciplined procedures. The installation area should be classified by a qualified expert. Equipment must match the correct ATEX code, zone, and gas or dust group. Documentation and markings should always be verified before installation. Only certified technicians may perform service or maintenance, and no modifications should be made to ATEX-certified equipment without formal re-approval. These practices ensure continued safety, reliability, and regulatory compliance in all explosive environments.
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