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By: Grant Laidlaw
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Many people ask for assistance in the understanding of theoretical and practical aspects of the industry. I will endeavour to enlighten. We are going back to basics as I have questions coming in that indicate that the basic understanding necessary to work in industry is not in place.
Riaan asks: Hi Grant, We are being asked questions on ATEX, For example do we comply with ATEX and for our ATEX documentation, Can you shed some light on this please. Thank you.
Hi Riaan, yes I can help.
International and particularly in Europe two prominent safety standards that govern the design, manufacturing and use of equipment in hazardous environments are ATEX and IECEx (International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres).
l can provide an overview of ATEX and IECEx in relation to our industry.
Both ATEX and IECEx are responses to the need for standardised safety regulations and certifications in potentially explosive environments. While ATEX is a European directive aimed at harmonising safety standards within the European Union, IECEx is an international certification system that seeks to simplify and streamline the certification process for hazardous area equipment on a global scale. By understanding both ATEX and IECEx, manufacturers and users can be confident their equipment is safe, compliant and suitable for use in hazardous environments around the world.
A brief history of ATEX and IECEx
ATEX was developed to ensure the safety of equipment and protective systems used in potentially explosive atmospheres within the European Union. The term “ATEX” comes from the French phrase “ATmosphères EXplosibles”, which refers to explosive atmospheres. Before ATEX, each European country had its own set of regulations governing equipment used in hazardous areas. This fragmentation made it difficult for companies to understand and comply with varying requirements across different regions.
The first ATEX directive (ATEX 100a) was introduced in 1994, and it was later replaced by the ATEX 137.
IECEx is an international certification system developed by the International Electrotechnical Commission (IEC) to harmonise and simplify the certification process for hazardous area equipment globally. Established in 1996, the IECEx System aims to facilitate international trade in equipment and services for use in explosive atmospheres while maintaining the required level of safety. The IECEx System comprises three certification schemes: IECEx Certified Equipment Scheme, IECEx Certified Service Facilities Scheme, and IECEx Scheme for Certification of Personnel Competence.
ATEX governs how systems are designed and operated when using flammable refrigerants (such as hydrocarbons like propane/R290 or other A2L, A2 and A3 fluids ).
We have of course SANS Standards which follow the same type of guidelines but are due for an update.
Riaan what does this mean to you?
Key Aspects in Air Conditioning / Refrigeration
- Flammable Refrigerants: As the industry shifts away from traditional non-flammable F-gases toward natural flammable refrigerants, a new safety aspect emerges: severe leak can mix with ambient air and create an explosive atmosphere.
- Ignition Prevention: ATEX-certified or ATEX-compliant refrigeration equipment (such as special fridges, freezers, compressors, or fans) is built to eliminate potential ignition sources, featuring spark-free electrical components, hermetic seals, and controlled surface temperatures.
- Not Every System is ATEX: Using a flammable refrigerant like R290 does not automatically mean the entire refrigeration system or room must be ATEX-certified. Standard sealed commercial or industrial systems rarely leak enough gas per minute to trigger an explosive zone. ATEX rules apply only if a site-specific risk assessment officially classifies an area as a hazardous (explosive) zone.
- Service and Maintenance: Opening a refrigeration circuit for repairs, charging, or recovery can temporarily create localised flammable pockets, requiring strict risk assessments, ventilation, and trained technicians.
Unlike R290, R744 (carbon dioxide) is an A1 refrigerant, meaning it is non-flammable and non-toxic. Because it cannot create an explosive atmosphere, ATEX regulations do not apply to R744 systems.
However, R744 comes with its own severe safety challenges due to its extreme operating pressures and asphyxiation risks.
R744 Safety Risks (Non-ATEX)
- Extreme Operating Pressures: R744 systems operate at pressures up to 5 to 10 times higher than standard refrigerants (often exceeding 120 bar on the high side). This requires specialised high-pressure components.
- Asphyxiation Hazard: Because CO2 is heavier than air, a major leak in an enclosed space (like a plant room or cold room) will displace oxygen and pool on the floor.
- Dry Ice Formation: If R744 is trapped or vented too quickly, the sudden pressure drop can cause the liquid to flash into solid dry ice inside pipes or valves, potentially blocking safety relief lines and causing a rupture.
Safety Requirements for R744
Because ATEX doesn’t apply, compliance falls under standard refrigeration safety codes (like EN 378 in Europe or ASHRAE 15 in the US):
- Gas Detection: Fixed CO2 sensors are mandatory in plant rooms and walk-in cold rooms to alert staff to a leak before oxygen levels drop dangerously.
- Emergency Ventilation: Sensors must be tied to mechanical exhaust fans to clear out leaking CO2.
- Trapped Liquid Relief: Every section of piping that can be isolated by valves must have a pressure-relief valve to prevent catastrophic pipe bursts from thermal expansion.
When using R290 (propane) however, you are dealing with an A3 refrigerant, meaning it is highly flammable and requires strict adherence to safety standards.
Because R290 has an extremely low Global Warming Potential (GWP), it is being widely introduced, but its flammability triggers specific engineering and safety protocols under ATEX guidelines.
I find that there exists the perception that R290 is only used in smaller systems, this is not the case. R290 can be and is currently used in systems that include large industrial chillers and the trends indicate that the use of R290 will increase across the entire spectrum of equipment encompassed by the air conditioning and refrigeration sectors.
R290 and ATEX Compliance
Charge Limits Determine Risk: If a system leaks, the concentration of R290 must stay below the Lower Flammability Limit (LFL).
- Factory-Sealed Hermetic Systems: For small commercial equipment (like bottle coolers or plug-in display cases) standards allow up to 500g without requiring ATEX certification for the room itself, provided the equipment meets component safety standards (like EN 60335-2-89).
- Large Systems: For larger split systems or industrial chillers with bigger charges, an ATEX Zoning Assessment is required to classify the space.
Spark-Free Components: Any electrical component in close proximity to the refrigeration circuit must be ATEX-certified or sealed so it cannot create an electrical arc. This applies to:
Compressors and terminal boxes, fan motors, Thermostats, relays, pressure switches etc.
Ventilation and Monitoring:
For larger R290 charges, rooms often require leak detection sensors tied to automated mechanical ventilation to disperse propane before it reaches an explosive concentration.
Establish perimeters when working with R290
There is no single, fixed perimeter distance laid down by the ATEX directives for working with R290, perimeter distances are not hardcoded; instead, they must be calculated dynamically through a site-specific risk assessment.
However, standard safety norms, manufacturer specifications, and standard ATEX assessment models dictate distinct perimeter zones depending on the activity:
Temporary Maintenance & Servicing Perimeter
When a technician opens a refrigeration circuit to work on an R290 system, a temporary ATEX Zone 2 is established:
- The Standard Work Perimeter: Best practice and standard safety training manuals dictate a minimum 3-meter radius perimeter clearance around the workspace.
- Expanded Intervention Perimeter: For intensive work directly on the refrigeration circuit (such as brazing or recovery), safety protocols frequently require an expanded zone of 5 to 6 meters clear of any ignition sources.
Theoretical Jet Leak Calculations (EN 60079-10-1)
An uncontrolled R290 gas release under ATEX guidelines, the hazardous jet length (where the gas-to-air mixture stays above the Lower Flammability Limit) typically scales as follows:
- 1 meter for a small (0.25 mm) puncture.
- 2 meters for a larger (1mm) puncture.
Riaan let me create a typical scenario
We are performing general air conditioning repairs on an R290 mid-wall split system.
Because R290 is a highly flammable A3 refrigerant, you must establish a temporary ATEX Zone 2 hazardous area before cracking open the system.
Safety Perimeter for Repairs
For a standard split system repair, you must enforce a minimum 3-meter radius safe zone around the indoor or outdoor unit you are servicing.
Within this 3-meter perimeter, you must ensure:
- Zero ignition sources: No phones, unsealed power tools, or standard electrical switches etc.
- No low-lying traps: Ensure there are no floor drains, open basement stairs, or ventilation ducts within this zone. Because R290 is heavier than air, any leaked gas will sink and pool in low areas.
- Continuous monitoring: A calibrated flammable gas leak detector must be active at floor level within this perimeter at all times.
R290 Work Checklist
When preparing to break into the split system circuit, follow these sequential steps to ensure compliance:
Isolate Power
Turn off the mains power to the AC unit outside your 3-meter perimeter to prevent any arcing switches from creating a spark.
Ventilate the Area
Set up a DC extraction / Ventilation fan if you are working indoors.
Ensure a continuous cross-breeze to instantly dilute any accidental gas release.
Use the Right Tools
Use equipment specifically rated for flammable refrigerants (spark-free switches).
Ensure your vacuum pump switch is spark-free, or turn it on/off outside the 3-meter zone.
Brazing Protocol
If brazing is required, you must thoroughly purge the entire circuit with oxygen-free nitrogen and verify with your gas detector that the internal R290 concentration is at 0%.
Riaan you are most likely dealing with a European based company that will no doubt expect you to follow ATEX Directives. As this applies to flammable environments unless you are working with Flamable refrigerants ATEX does not apply. However should you be using flammables then yes the expectation would naturally be that you should comply. Having said that, it will be well worth implementing ATEX standards in any company or for any person working with flammable refrigerants. This simply represents a safe way to work when dealing with Flammable refrigerants. We have tens of thousands of systems utilising flammable refrigerants in the country. Most domestic refrigeration systems utilise R600a and most beverage coolers now operate on R290. In addition R290 split air conditioning systems are now being introduced into South Africa. We need to, as an industry, prepare for these changes.
Riaan, thank you for your question. I hope that this helps with your understanding of ATEX and the implications thereof.
Grant Laidlaw
REFERENCES:
ACRA
ASHRAE
Institute of Refrigeration Ireland
ATEX Workplace 1999/92/EC (risk assessment, zones)
ATEX Equipment 2014/34/EU
EN 60079-10-1