SUCO ESI North America maintains comprehensive ATEX/IECEx certified pressure sensor portfolios serving oil & gas, chemical processing, pharmaceutical manufacturing, and other industries where explosive atmospheres pose constant risks. This complete guide demystifies ATEX pressure sensor certification—explaining directive requirements, decoding Ex markings, comparing protection methods, and guiding proper sensor selection for hazardous area applications worldwide.
⚠️ Understanding ATEX: The European Explosive Atmosphere Directive
What is ATEX?
ATEX derives from the French “ATmosphères EXplosibles” and encompasses two European directives governing equipment and protective systems for explosive atmospheres:
ATEX Directive 2014/34/EU (Equipment Directive)
- Scope: Manufacturers and importers of equipment and protective systems intended for use in potentially explosive atmospheres
- Requirements: Equipment must undergo conformity assessment, receive EC-Type Examination Certificate from Notified Body, bear CE marking with Ex symbol
- Application: Pressure sensors, transmitters, switches, and all electrical/mechanical equipment used in ATEX zones
- Legal Status: Mandatory for equipment sold in EU since July 2003 (updated 2014)
ATEX Directive 1999/92/EC (Workplace Directive)
- Scope: Employers operating facilities where explosive atmospheres may occur
- Requirements: Risk assessment, area classification, explosion protection document, use of ATEX-certified equipment
- Application: Oil refineries, chemical plants, grain elevators, pharmaceutical facilities, any workplace with explosive atmosphere potential
- Legal Status: Mandatory for employers in EU member states
ATEX vs. IECEx: Global Harmonization
While ATEX applies in Europe, IECEx (International Electrotechnical Commission Explosive Atmospheres) provides global certification scheme recognized by 35+ countries:
| Aspect | ATEX | IECEx |
|---|---|---|
| Geographic Scope | EU + EEA countries (27 EU + 3 EEA) | 35+ countries worldwide including Australia, Canada, China, India, Saudi Arabia |
| Technical Standards | EN standards (harmonized with IEC) | IEC standards (60079 series) |
| Certification Bodies | EU Notified Bodies | IECEx Certification Bodies (ExCBs) |
| Marking | CE mark + Ex symbol + specific codes | Ex symbol + specific codes (no CE mark) |
| Validity | Legally required in EU | Accepted in participating countries, often alongside national schemes |
💡 Practical Approach: Many manufacturers including SUCO ESI obtain both ATEX and IECEx certification simultaneously, enabling global market access with minimal additional effort since technical requirements substantially overlap.
🏭 Zone Classification: Understanding Hazardous Area Categories
Gas/Vapor Explosive Atmosphere Zones
ATEX classifies areas based on explosive atmosphere presence likelihood:
Zone 0 (Extreme Hazard)
- Definition: Explosive gas atmosphere present continuously, for long periods, or frequently
- Examples: Inside fuel tanks, closed chemical reactor vessels, vapor space in storage tanks
- Duration: Explosive atmosphere present >1,000 hours/year (>10% of time)
- Equipment Requirement: Category 1G (“very high” protection level) – e.g., intrinsically safe (ia)
- Sensor Application: Tank level/pressure monitoring, reactor pressure control
Zone 1 (High Hazard)
- Definition: Explosive gas atmosphere likely to occur in normal operation occasionally
- Examples: Pump/compressor seal areas, filling stations during operation, areas near Zone 0
- Duration: Explosive atmosphere present 10-1,000 hours/year (0.1-10% of time)
- Equipment Requirement: Category 1G or 2G (“high” protection) – e.g., intrinsically safe (ia/ib), flameproof (d)
- Sensor Application: Process line pressure monitoring, compressor discharge pressure, loading rack instrumentation
Zone 2 (Moderate Hazard)
- Definition: Explosive gas atmosphere not likely in normal operation, if occurs will exist briefly
- Examples: Areas beyond Zone 1 boundaries, maintenance areas, normally sealed equipment
- Duration: Explosive atmosphere present <10 hours/year (<0.1% of time)
- Equipment Requirement: Category 1G, 2G, or 3G – various protection methods acceptable
- Sensor Application: Remote monitoring, auxiliary systems, non-process-critical measurement
Dust Explosive Atmosphere Zones
Combustible dust presents different but equally serious explosion risks:
| Zone | Dust Cloud Presence | Equipment Category | Examples |
|---|---|---|---|
| Zone 20 | Continuous/long periods/frequent | Category 1D | Inside silos, dust collectors, powder transfer equipment |
| Zone 21 | Likely occasionally in normal operation | Category 1D or 2D | Near dust handling equipment, filling/emptying areas |
| Zone 22 | Not likely, brief if occurs | Category 1D, 2D, or 3D | Adjacent areas to dust zones, maintenance areas |
⚠️ Common Dust Hazards: Grain dust (elevators, mills), pharmaceutical powders (tablet compression), metal dust (aluminum, magnesium machining), coal dust (mining, power plants), plastic/resin powders (manufacturing), sugar dust (food processing)
🛡️ Protection Methods (Types of Protection)
Intrinsic Safety (Ex ia / Ex ib)
Intrinsic safety represents the most common protection method for ATEX pressure sensors:
Principle of Operation
- Limits electrical energy (voltage, current, power) to levels incapable of igniting explosive atmosphere
- Achieved through energy-limiting circuits (zener diode barriers, galvanic isolators)
- Even under fault conditions (short circuit, component failure), insufficient energy for ignition
- Requires intrinsically safe equipment in hazardous area plus associated apparatus (barriers) in safe area
Categories
- Ex ia: Two independent faults cannot cause ignition (Zone 0/20 rated)
- Ex ib: One fault plus one additional fault cannot cause ignition (Zone 1/21 rated)
- Ex ic: One fault cannot cause ignition (Zone 2/22 rated)
Advantages for Pressure Sensors
- ✅ Simple installation—no special enclosures or purging required
- ✅ Can perform live work (hot work) on barriers in safe area
- ✅ Suitable for Zone 0/20 applications
- ✅ Low maintenance—no moving parts or consumables
- ✅ Wide sensor selection available
Limitations
- ⚠️ Voltage/current limited—typically 28V max, affects cable lengths
- ⚠️ Requires approved barriers in safe area
- ⚠️ Cable parameter restrictions (capacitance, inductance)
Flameproof Enclosure (Ex d)
Flameproof protection allows internal ignition but contains explosion:
Principle of Operation
- Robust enclosure withstands internal explosion pressure
- Flamepath joints (threaded connections, machined flanges) cool escaping gases below ignition temperature
- Prevents internal explosion propagating to external explosive atmosphere
Application to Pressure Sensors
- Housing machined to precise tolerances maintaining flamepath integrity
- Cable entries via certified cable glands with thread engagement requirements
- Suitable for Zone 1/21 applications
- Common in higher-power sensors requiring more than intrinsically safe levels
Advantages
- ✅ No external barriers required
- ✅ Higher power levels possible
- ✅ Simple system architecture
Limitations
- ⚠️ Heavy, expensive enclosures
- ⚠️ Cannot open for service in hazardous area (must de-energize)
- ⚠️ Not suitable for Zone 0/20
- ⚠️ Strict installation requirements (thread engagement depth, etc.)
Other Protection Methods
| Protection Type | Code | Principle | Pressure Sensor Use |
|---|---|---|---|
| Increased Safety | Ex e | Enhanced construction preventing sparks/hot surfaces | Junction boxes, terminal compartments |
| Encapsulation | Ex m | Components embedded in resin preventing ignition | Electronics encapsulation, PCB protection |
| Pressurization | Ex p | Positive internal pressure excluding explosive atmosphere | Analyzer houses, large instrument enclosures |
| Oil Immersion | Ex o | Components submerged in oil | Rare in modern pressure sensors |
| Type n | Ex nA/nC/nR | Non-sparking, restricted breathing, sealed | Zone 2/22 applications |
🔍 Decoding ATEX Ex Markings
Understanding the Complete Ex Marking
ATEX-certified pressure sensors bear markings containing critical safety information:
Example Marking Decoded
Mark: CE 0102 ⚠ II 2G Ex ia IIC T6 Gb
| Symbol | Meaning | This Example |
|---|---|---|
| CE 0102 | Conformity mark + Notified Body number | Certified by Notified Body #0102 |
| ⚠ | Warning symbol for explosive atmospheres | Special conditions may apply |
| II | Equipment Group (I=mining, II=surface industries) | Surface industries (not mines) |
| 2G | Equipment Category and atmosphere type | Category 2 (Zone 1), Gas atmospheres |
| Ex | Explosive atmosphere protection | Explosion-protected equipment |
| ia | Type of protection | Intrinsically safe, two-fault protection |
| IIC | Gas group (IIA/IIB/IIC) | Suitable for most flammable gases including hydrogen, acetylene |
| T6 | Temperature class | Max surface temp 85°C (suitable for gases with ignition temp >85°C) |
| Gb | Equipment Protection Level (EPL) | “High” protection level for Zone 1 |
Gas Groups Explained
Gas classification determines ignition difficulty:
- Group IIA: Propane, butane, ethanol, ammonia, carbon monoxide (easiest to protect against)
- Group IIB: Ethylene, dimethyl ether (intermediate ignition sensitivity)
- Group IIC: Hydrogen, acetylene, carbon disulfide (most easily ignited, requires highest protection)
💡 Selection Rule: Equipment marked IIC suitable for all gases. Equipment marked IIB suitable for IIB and IIA. Equipment marked IIA suitable for IIA only. SUCO ESI ATEX sensors typically certified IIC for maximum application flexibility.
Temperature Classes
Maximum surface temperature must stay below gas autoignition temperature:
| T-Class | Max Surface Temp | Suitable for Gases with Ignition Temp | Example Gases |
|---|---|---|---|
| T1 | 450°C | >450°C | Ammonia (630°C) |
| T2 | 300°C | 300-450°C | Ethanol (363°C), kerosene (210°C) |
| T3 | 200°C | 200-300°C | Gasoline (280°C) |
| T4 | 135°C | 135-200°C | Acetaldehyde (175°C) |
| T5 | 100°C | 100-135°C | Carbon disulfide (90°C) |
| T6 | 85°C | >85°C | Hydrogen (560°C), acetylene (305°C) |
⚠️ Important: Hydrogen sensors often specify T6 not because hydrogen ignites at 85°C (it ignites at 560°C) but to ensure sensor works safely in any Group IIC gas, including carbon disulfide which ignites at 90°C.
🔧 Selecting ATEX-Certified Pressure Sensors
Application-Specific Selection Guide
Oil & Gas Production
Typical Requirements:
- Zone 1/2 classification for most process areas
- Group IIC (hydrogen sulfide present in sour gas)
- T4-T6 temperature class depending on process temperature
- High pressure capability (up to 10,000+ PSI)
- Corrosion-resistant materials (Inconel, Hastelloy)
Recommended: SUCO ESI ATEX-certified transducers with II 2G Ex ia IIC T6 rating, 316L or Inconel construction
Chemical Processing
Typical Requirements:
- Zone 1/2 for process areas, Zone 20/21 if handling combustible powders
- Group IIB/IIC depending on chemicals (check MSDS)
- Material compatibility with aggressive chemicals
- Sanitary connections (tri-clamp) for pharmaceutical applications
- Clean room compatibility (low particle generation)
Recommended: Ex ia sensors with chemically inert sapphire diaphragms, FFKM seals, 316L or Hastelloy wetted materials
Grain Handling and Food Processing
Typical Requirements:
- Zone 20/21/22 for dust atmospheres
- Category 1D or 2D equipment
- IP6X dust ingress protection (dust-tight)
- Food-grade materials (316L stainless, FDA-compliant seals)
- Easy cleaning (smooth surfaces, minimal crevices)
Recommended: Ex ta/tb dust-ignition protection, IP67 minimum environmental rating, 3-A sanitary design where required
Pharmaceutical Manufacturing
Typical Requirements:
- Zone 1/2 for solvent handling areas
- Zone 20/21 for powder handling
- Both gas and dust certification often needed
- Sanitary design, CIP/SIP compatibility
- Material certifications (USP Class VI, ISO 10993)
- Contamination prevention (smooth surfaces, no lubricants)
Recommended: Dual gas/dust rated sensors (II 2G/2D), 316L electropolished surfaces, EHEDG compliance
Common Selection Mistakes to Avoid
- ❌ Wrong Zone Rating: Using Category 2G (Zone 1) equipment in Zone 0 area—not permitted
- ❌ Insufficient Gas Group: IIA sensor in hydrogen application—won’t protect against H₂ ignition
- ❌ Wrong Temperature Class: T4 sensor (135°C max) in application with 100°C ambient + 50°C self-heating = 150°C surface temp—exceeds T-class
- ❌ Ignoring Dust: Gas-only certification in area with combustible dust present
- ❌ Improper Installation: Certified sensor installed with non-certified cable gland—breaks Ex chain
- ❌ Missing Documentation: No Ex installation drawings or special conditions—audit fail
🛠️ Installation Requirements for ATEX Sensors
General ATEX Installation Rules
Cable and Cable Glands
- Use certified cable glands appropriate for sensor Ex type (Ex ia requires approved glands)
- Maintain minimum thread engagement (typically 5 threads or per manufacturer specification)
- Use appropriate cable type (armored, unarmored as specified)
- Respect cable parameter limits (capacitance, inductance for ia circuits)
- Install drip loops preventing water entry
- Seal unused cable entries with certified stopping plugs
Grounding and Bonding
- Earth metal sensor housings per manufacturer instructions
- Maintain equipotential bonding across installations
- Use corrosion-resistant ground connections
- Verify ground continuity after installation
Documentation
- Maintain installation drawings showing Ex equipment locations
- Keep copies of EC-Type Examination Certificates
- Document special conditions of use (if any)
- Record inspection and maintenance activities
- Create Explosion Protection Document (per Directive 1999/92/EC)
Intrinsically Safe Circuit Installation
Barrier Selection and Placement
- Install barriers in safe (non-hazardous) area
- Match barrier parameters to sensor requirements (verify Um, Im, Pm)
- Ensure barrier entity parameters accommodate cable capacitance/inductance
- Ground barriers to earth (single-point ground typical)
Cable Routing
- Segregate IS circuits from non-IS circuits (separate conduit or minimum 50mm spacing)
- Blue insulation for IS wiring (recommended practice, not always mandatory)
- Label conduits: “Intrinsically Safe Wiring”
- Calculate and document cable parameters
💼 ATEX Compliance Costs and Benefits
Cost Comparison
| Item | Standard Sensor | ATEX-Certified Sensor | Premium |
|---|---|---|---|
| Sensor Cost | $300-$500 | $600-$1,200 | +100-140% |
| Installation Labor | $200 | $400-$600 | +100-200% |
| Barriers/Associated Equipment | $0 | $200-$400 (if ia) | N/A |
| Documentation | $50 | $200-$500 | +300-900% |
| Total Installed Cost | $550-$750 | $1,400-$2,700 | +155-260% |
Benefits Justifying Premium
- ✅ Legal Compliance: Required by law in EU, avoiding penalties and liability
- ✅ Safety: Preventing explosions that cause fatalities, injuries, and facility destruction
- ✅ Insurance: Lower premiums, avoiding coverage exclusions for non-compliant equipment
- ✅ Operational Continuity: Preventing $1M+ per day shutdown costs from incidents
- ✅ Global Market Access: Enabling equipment sales and project execution in 60+ countries
- ✅ Reputation Protection: Avoiding brand damage from safety incidents
💰 ROI Perspective: A single prevented explosion saving one life and avoiding $10M+ in damages justifies ATEX compliance costs across thousands of sensors. The question isn’t “Can we afford ATEX?” but “Can we afford not to comply?”
🌟 SUCO ESI ATEX-Certified Pressure Sensor Solutions
SUCO ESI provides comprehensive ATEX pressure sensor portfolios with certifications covering global hazardous area requirements:
ATEX Certification Coverage
- ✅ Multiple Protection Types: Ex ia, Ex ib, Ex d available
- ✅ Gas and Dust: II 2G and II 2D dual certifications
- ✅ Broad T-Class Range: T1-T6 options for various process temperatures
- ✅ Group IIC Rating: Suitable for all flammable gases including hydrogen
- ✅ IECEx Equivalent: Dual ATEX/IECEx certification for global deployment
- ✅ North American Options: CSA/UL Class I Div 1 certification available
Application-Specific Solutions
- Hydrogen ATEX Sensors: II 1G Ex ia IIC T6 for fuel cell and production applications
- High-Accuracy ATEX Transducers: ±0.25% accuracy with SoS technology and ATEX certification
- Explosion-Proof Switches: Ex d flameproof designs for high-power applications
- Dust-Ignition Protected: Ex ta/tb certification for powder handling
Technical Support and Compliance Assistance
- Application Engineering: Zone classification review, sensor selection guidance
- Installation Support: Ex installation drawings, cable parameter calculations
- Documentation: EC-Type Certificates, installation manuals, special conditions
- Training: ATEX awareness, proper installation techniques
- Compliance Audits: Installation verification, documentation review
Contact SUCO ESI for ATEX-Certified Sensors
📞 Phone: 1-800-473-7313
🌐 Website: www.sucoesi.com
📧 Contact: Request ATEX Technical Support
Related Resources:
- Complete Guide to Electrical Pressure Sensors
- Browse ATEX-Certified Product Line
- Download ATEX Certificates and Technical Documentation
- Official EU ATEX Information
ATEX pressure sensor certification ensures equipment safety in explosive atmospheres, protecting lives, assets, and operational continuity. SUCO ESI’s comprehensive ATEX/IECEx certified portfolio combined with expert application support enables compliant, safe installations worldwide. ⚠️
ATEX Pressure Sensor Certification