Short answer: An ATEX-rated fan is mandatory wherever combustible dust or flammable gas/vapor may occur in hazardous concentration — grain handling, biomass, paint booths, chemical, and solvent processes. Specifiers must define the hazardous zone (gas 0/1/2 or dust 20/21/22), the ignited substance and its auto-ignition temperature, then select certified construction (e.g., II 2G Ex d IIB T4 for gas, II 2D for dust). Compliance follows Directive 2014/34/EU.
Under the EU ATEX Directive 2014/34/EU, equipment used in potentially explosive atmospheres must be suitably constructed. If a process can produce a flammable atmosphere, a standard fan is not acceptable — it becomes an ignition source. This is a safety and legal requirement, not a performance preference.
Atmosphere | Zone | Definition |
Gas/vapor | 0 | Explosive mixture present continuously or long periods |
Gas/vapor | 1 | Likely to occur in normal operation |
Gas/vapor | 2 | Not likely, or only brief |
Dust | 20 | Cloud present continuously or long periods |
Dust | 21 | Likely in normal operation |
Dust | 22 | Not likely, or only brief |
Group I: mining (firedamp). Group II: surface industry (most plants).
Categories 1/2/3 indicate protection level (1 = very high, for Zone 0/20; 2 = high, for Zone 1/21; 3 = normal, for Zone 2/22).
Marking example: II 2G Ex d IIB T4 — Group II, Category 2, gas; flameproof enclosure; IIB gas group; T4 temperature class.
ATEX-certified motor with appropriate protection (Ex d flameproof, Ex e increased safety, or Ex t for dust).
Spark-resistant construction (non-sparking impeller, brass/bronze or treated alloy where required).
Earthing of rotating and static parts.
Temperature class (T1–T6) must exceed the auto-ignition temperature of the substance.
For dust: smooth internal surfaces to prevent deposit ignition.
Hazardous zone (gas or dust, number)
Ignited substance and its group (IIA/IIB/IIC; IIIA/IIIB/IIIC for dust)
Auto-ignition temperature → temperature class
Required equipment category
Certifying body and marking
Ducting and ancillary equipment also ATEX-rated
Q: When do I actually need an ATEX fan?A: Whenever the airstream may carry flammable gas/vapor or combustible dust in a classified zone — common in grain, biomass, paint, chemical, and solvent processes.
Q: What is the difference between Zone 1 and Zone 21?A: Zone 1 is gas/vapor likely in normal operation; Zone 21 is dust likely in normal operation. They are different atmospheres but similar risk levels.
Q: Can I use a "explosion-proof" motor with a standard impeller?A: No. The full air path (impeller, housing, inlet) must be spark-resistant and certified; the motor alone does not make the fan ATEX-compliant.
Q: What does "T4" mean on the rating?A: T4 is a temperature class meaning the surface temperature stays below 135°C — it must be lower than the substance's auto-ignition temperature.