ATEX Explosion-Proof Push Buttons
In environments where flammable gases, vapors, or combustible dust are present, standard push buttons can be an ignition source. ATEX-certified explosion-proof buttons are designed to prevent this.
What is ATEX?
ATEX comes from the French "ATmosphères EXplosibles." It refers to two EU directives that govern equipment and workplaces in explosive atmospheres. If you operate in the EU, equipment in hazardous areas must be ATEX certified. Outside the EU, the equivalent is IECEx (International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres).
Zone classifications
Hazardous areas are classified by how likely an explosive atmosphere is to be present:
| Zone | Atmosphere | Frequency | Examples |
|---|---|---|---|
| Zone 0 | Gas/vapor | Continuously present | Inside tanks, vessels |
| Zone 1 | Gas/vapor | Likely in normal operation | Near vents, filling points, relief valves |
| Zone 2 | Gas/vapor | Not likely, short duration | General refinery areas, pump rooms |
| Zone 20 | Combustible dust | Continuously present | Inside dust collectors, silos |
| Zone 21 | Combustible dust | Likely in normal operation | Grain elevators, flour mills, coal handling |
| Zone 22 | Combustible dust | Not likely, short duration | Areas near dust processing equipment |
Temperature classes
Every ATEX device has a temperature class (T1-T6) indicating the maximum surface temperature it can reach. This must be below the auto-ignition temperature of the gas present:
- T6 (85°C) — Most restrictive. Required for carbon disulfide (CS2).
- T5 (100°C) — Required for some chemical processes.
- T4 (135°C) — Common for general chemical plants.
- T3 (200°C) — Suitable for most petroleum products.
- T2 (300°C) — Covers acetylene.
- T1 (450°C) — Least restrictive. Covers methane and most common gases.
Industries that need ATEX buttons
- Oil & gas — refineries, drilling platforms, gas processing plants
- Chemical processing — reactors, mixing vessels, storage facilities
- Pharmaceutical — solvent handling areas, powder processing
- Food & beverage — grain silos, flour mills, sugar processing, distilleries
- Mining — underground coal mines (methane), ore processing
- Paint & coatings — spray booths, mixing rooms
- Woodworking — sawdust extraction, sanding areas
How to choose the right ATEX button
- Know your zone — Zone 1 requires Ex d (flameproof) or Ex e (increased safety). Zone 2 can use Ex nA (non-sparking).
- Know your gas group — IIC (hydrogen) is most restrictive. Most chemical plants need IIB (ethylene). IIA (propane) covers basic petrochemical.
- Know your temperature class — Check the auto-ignition temperature of the gas and select a T-class below it.
- Standard buttons don't work — Even if a standard IP67 button looks sealed, it hasn't been tested to prevent internal sparks from igniting the external atmosphere. ATEX certification involves specific enclosure testing.