How do metal enclosures meet the ATEX certification requirements of the chemical industry?

 

 

Anji Huacheng Electrics Co., Ltd.

 

Anji Huacheng Electrics Co., Ltd., operating under the brand PROTA, is a leading manufacturer of metal enclosures and electrical cabinets, renowned for precision engineering and compliance with global safety standards. Based in Zhejiang Province, China, the company's product range has wall-mounted units, floor-standing cabinets, stainless steel enclosures, knock-down designs, and custom-engineered solutions, serving chemical processing, petrochemicals, pharmaceuticals, and industrial automation-industries where explosive atmospheres are a persistent risk.

 

PROTA's metal enclosures are defined by their adherence to rigorous international certifications (TUV, SGS, CE, and ATEX) and innovative design features: modular architectures for easy on-site assembly, flat-packaging for cost-efficient logistics, and durable construction tailored to harsh environments. With over 100 patents and a 40,000㎡ production facility, the company specializes in enclosures that balance protection, functionality, and compliance-critical for equipment operating in zones where flammable gases, vapors, or dusts may be present.

 

In the chemical industry, ATEX certification (from the EU directive 2014/34/EU) is not merely a regulatory box to check; it is a foundational safety requirement. It ensures equipment does not act as an ignition source in explosive atmospheres, safeguarding workers, facilities, and the environment. PROTA's metal enclosures meet these standards through a holistic approach to design, materials, and manufacturing, making them integral to safe chemical operations.

 

 

ATEX certification

 

ATEX certification is a comprehensive framework, encompassing design, testing, and documentation to ensure equipment safety in explosive environments. For metal enclosures, it is rooted in two core objectives: preventing ignition of external explosive atmospheres and containing internal explosions if they occur.

 

The certification process involves rigorous third-party testing, where enclosures are subjected to simulated explosive conditions, corrosion challenges, and temperature extremes to validate performance. This testing is not limited to the enclosure as a whole; individual components-hinges, cable glands, gaskets-must meet ATEX standards, ensuring system-wide integrity.

 

ATEX categorizes hazardous zones based on the likelihood and duration of explosive atmospheres, dictating the stringency of requirements:

 

Gas/vapor zones: Zone 0 (continuous presence), Zone 1 (intermittent presence), Zone 2 (rare presence).

Dust zones: Zone 20 (continuous dust clouds), Zone 21 (intermittent dust clouds), Zone 22 (rare dust accumulation).

 

Enclosures must be certified for specific zones, with Zone 0/20 requiring the most robust protection. PROTA's ability to tailor enclosures to these zones-through material selection, sealing, and structural design-positions them as a trusted partner for chemical facilities navigating complex ATEX requirements.

 

How metal enclosures meet ATEX requirements

 

The foundation of safety

 

PROTA's material selection is guided by ATEX's mandate to prevent ignition and resist chemical degradation:

 

Stainless steel (316 grade): The cornerstone of chemical industry enclosures, 316 stainless steel offers superior resistance to corrosive substances, which is critical for maintaining structural integrity in Zone 1 and 2 environments. Its non-sparking properties, even when struck by tools or debris, eliminate a common ignition source. For high-salt environments (coastal chemical plants), 316L (low-carbon variant) further reduces corrosion risk.

Aluminum alloys (5000 and 6000 series): Used in lighter enclosures for Zone 2 or 22 applications, these alloys are treated with chromate conversion coatings or powder coatings to enhance corrosion resistance. Their inherent conductivity allows for effective grounding, dissipating static electricity that could ignite flammable dusts or vapors.

Non-ferrous hardware: Hinges, latches, and fasteners are crafted from brass, bronze, or Monel (a nickel-copper alloy)-metals that do not produce sparks when friction occurs. This is particularly critical in Zone 1, where a single spark from metal contact could ignite propane or benzene vapors.

 

These materials are not chosen in isolation; PROTA conducts compatibility testing with common chemical substances, ensuring enclosures remain stable over decades of exposure.

 

Containing explosions to protect the perimeter

 

ATEX's most stringent requirement-critical for Zone 0, 1, 20, and 21-involves containing internal explosions, preventing them from igniting external atmospheres. PROTA achieves this through precision engineering:

 

Flameproof joints: Enclosure doors, panels, and access points feature machined "flame paths"-interlocking metal surfaces with tightly controlled gaps (0.1–0.5mm, depending on joint length). If an internal explosion occurs (from a short circuit in the inverter), these gaps cool and quench flames as they escape, reducing their temperature below the ignition point of external flammables. PROTA's computer numerical control (CNC) machining ensures these gaps are consistent across every unit, a level of precision impossible with manual fabrication.

Pressure-resistant construction: Enclosure frames use PROTA's patented 9-Folded framework profile, a reinforced design that distributes explosion pressure evenly across walls and corners. This prevents deformation or rupture, even when internal pressures reach 10–20 bar-typical of electrical component failures in explosive atmospheres.

Sealed penetrations: Cable glands, conduit entries, and sensor ports are equipped with ATEX-certified flameproof seals-often made from copper or brass-that maintain the enclosure's integrity. These components are tested to ensure they withstand pressure spikes and prevent flame propagation, with certification markings traceable to independent labs.

 

Eliminating ignition sources

 

ATEX mandates that enclosures eliminate all potential ignition sources, from static electricity to excessive heat. PROTA's designs address this through layered solutions:

 

Static dissipation: For dust-rich environments (Zones 21 and 22), where combustible dusts (pharmaceutical powders, polymer granules) pose risks, enclosures are treated with conductive coatings or bonded to grounding straps. This ensures static charges-accumulated from air flow or material contact-dissipate to earth, preventing sparks that could ignite dust clouds. PROTA's testing has measuring surface resistance (aiming for 10⁶–10⁹ ohms), the range deemed safe for dust zones.

Temperature control: Enclosure surfaces must remain below the "auto-ignition temperature" of surrounding substances (215°C for ethanol, 560°C for methane). PROTA integrates passive cooling features-heat sinks, louvered panels, and thermal insulation-to achieve this. In high-heat environments (near reactors), active cooling systems (ATEX-certified fans or heat exchangers) are added, with motors and controls themselves certified for explosive zones to avoid introducing new risks.

Arc containment: Internal components (contactors, relays) are housed in sub-enclosures or shrouded to contain arcs from electrical switching. This prevents hot particles from escaping and igniting external vapors-a critical feature for enclosures housing control systems in Zone 1.

 

Sustaining safety over time

 

Chemical environments accelerate degradation, and ATEX requires enclosures to maintain protective properties for their full service life (typically 15–20 years). PROTA's approach:

 

Multi-layer coatings: Enclosures destined for aggressive environments receive a three-step treatment: a zinc-rich primer (for corrosion resistance), an epoxy undercoat (to seal pores), and a polyester topcoat (for UV and chemical resistance). This system withstands 1,000+ hours of salt spray testing (per ASTM B117), far exceeding ATEX's minimum requirements.

Sealed designs: IP66/IP67 ratings ensure dust tightness and water resistance, preventing corrosive liquids or vapors from infiltrating and damaging internal components. Gaskets are made from Viton or EPDM-elastomers resistant to oils, solvents, and high temperatures-with compression limits engineered to maintain seals over repeated door openings.

Drainage systems: For outdoor or washdown environments (chemical cleaning facilities), enclosures have sloped roofs and weep holes (fitted with flameproof plugs) to expel accumulated moisture, reducing corrosion risks in Zone 2.

 

Testing and certification: Validating compliance

 

ATEX certification is not granted based on design alone; it requires rigorous testing by accredited bodies. PROTA's process ensures every enclosure meets these standards:

 

Component-level testing: Individual parts-flameproof joints, cable glands, hinges-are tested for flame quenching, pressure resistance, and corrosion before assembly. This modular approach ensures no weak link compromises the whole.

System-level certification: Assembled enclosures undergo explosive atmosphere testing, where they are exposed to flammable gas-air mixtures (propane, hydrogen) and ignited internally. Passing requires no external ignition and minimal structural damage. For dust zones, enclosures are tested with aluminum powder or cornstarch clouds to validate dust explosion containment.

Traceability: Each enclosure carries a unique serial number, linked to test reports, material certificates, and assembly records. This allows chemical facilities to trace compliance back to manufacturing, a requirement for ATEX audits.

 

Adaptations for dust vs. gas environments

 

ATEX distinguishes between gas/vapor (Zones 0–2) and dust (Zones 20–22) environments, each demanding tailored designs:

 

Gas/vapor zones: Enclosures prioritize flameproof joints and pressure resistance, as gas explosions propagate quickly and generate high pressure. PROTA adds pressure relief valves (certified for Zone 1) to vent excess pressure without compromising flame containment.

Dust zones: Dust explosions produce slower, more sustained pressure, requiring enclosures with thicker walls and tighter seals to prevent dust ingress. PROTA's dust-specific designs have smooth internal surfaces (to avoid dust accumulation) and quick-release panels for easy cleaning-critical for maintaining Zone 21/22 compliance.

 

PROTA's ATEX-compliant solutions in action

 

PROTA's metal enclosures address diverse chemical industry needs, from batch processing to continuous production:

 

Chlorine manufacturing plants: 316 stainless steel enclosures in Zone 1 protect control systems from corrosive chlorine gas, with flameproof joints preventing ignition of hydrogen (a byproduct) in case of electrical failure.

Pharmaceutical API production: Dust-tight enclosures in Zone 22 house motors and sensors, with smooth surfaces and anti-static coatings to avoid igniting combustible drug powders (lactose-based excipients).

Petrochemical storage terminals: Aluminum enclosures in Zone 2, fitted with UV-resistant coatings, protect pumps and meters from hydrocarbon vapors and coastal salt spray, with static grounding straps ensuring safe operation during tanker unloading.

 

Preserving ATEX compliance over time

 

ATEX compliance is not a one-time achievement; it requires ongoing maintenance. PROTA's enclosures are designed to facilitate this:

 

Inspection-friendly features: Removable panels and labeled access points allow technicians to check flameproof joints for corrosion or debris without disassembling critical components.

Replacement parts: PROTA supplies ATEX-certified replacement gaskets, hinges, and glands, ensuring repairs do not compromise compliance.

Documentation support: The company provides maintenance manuals tailored to ATEX requirements.

 

Metal enclosures as a pillar of chemical safety

 

Meeting ATEX certification in the chemical industry demands enclosures that balance protection, durability, and precision-qualities PROTA's metal enclosures deliver through material science, flameproof design, and rigorous testing. By addressing the unique risks of gas and dust explosive atmospheres, these enclosures do more than comply with regulations: they create a safer foundation for chemical operations, protecting workers, equipment, and communities.

 

As chemical processes grow more complex and global safety standards tighten, ATEX-compliant metal enclosures remain indispensable. PROTA's commitment to innovation-from CNC-machined flame paths to corrosion-resistant coatings-ensures these enclosures evolve alongside industry needs, sustaining their role as guardians of explosive environments.