How safe is your system in potentially explosive atmospheres really? A spark, leak or electrostatic discharge can have serious consequences, from production downtime to endangering people and the environment. The risk increases, especially in complex automation systems, if components are not harmonised with each other in accordance with standards. That is why effective explosion prevention and protection requires certified, internationally approved solutions that are reliable in every zone, for every industry.
Reliable explosion prevention and protection is based on three levels:
Together, they ensure safe and efficient system operation.
The IECEx system is the globally recognised foundation for the explosion prevention and protection of electrical equipment.
It defines standardised testing and certification procedures based on IEC standards and is used as a reference for national systems in many countries.
What you should know about IECEx:
The ATEX Directive (2014/34/EU) specifies requirements for equipment and protective systems in potentially explosive atmospheres within the EU. It describes how systems, components and accessories are assessed and approved in terms of their ignition sources, zone classifications and equipment categories.
What you should know about ATEX:
The USA and Canada have their own systems for classifying potentially explosive atmospheres: NEC 500 (Class/Division) and NEC 505 (Zone Concept). Certifications are carried out by organisations such as UL (Underwriters Laboratories) and FM (Factory Mutual), which test independently of IECEx.
What you should know about UL / FM:
China has introduced the national CCC Ex system (China Compulsory Certification – Explosion Protection), which replaces the former NEPSI approval. Certification is mandatory for the Chinese market and is based on national GB standards that are based on IEC standards.
What you should know about CCC Ex / NEPSI:
The Brazilian INMETRO system is based on IECEx, but requires local testing by accredited bodies (OCP). INMETRO certification is mandatory for the operation of electric devices in Ex zones.
What you should know about INMETRO:
KOSHA (Korea Occupational Safety and Health Agency) certifies devices for use in potentially explosive atmospheres. The requirements are based on IECEx, but necessitate additional national tests and identification.
What you should know about KOSHA:
In India, the Petroleum and Explosives Safety Organisation (PESO) regulates explosion prevention and protection for equipment in explosive atmospheres. Certification is required by law and is based on IECEx standards with additional national requirements.
This is what characterises PESO:
TIIS (Technology Institution of Industrial Safety) is Japan's national testing system for equipment in potentially explosive atmospheres. TIIS certification is mandatory for market access and ensures that products comply with Japanese safety standards.
What you should know about TIIS:
The ANZEx system is based on IECEx standards, supplemented by country-specific testing and identification requirements. It is the national certification for explosion prevention and protection of electrical equipment in Australia and New Zealand.
This is what characterises ANZEx:
In potentially explosive atmospheres, a distinction is made according to the frequency and duration of the occurrence of an explosive atmosphere. The correct zoning is crucial for selecting suitable components and reliably avoiding the risk of ignition.
An explosive atmosphere in zone 0 is present for longer periods of time or permanently, for example inside tanks, pipelines or reactors. That means this zone is particularly critical in terms of safety and requires materials, seals and temperature resistance of the highest standards. Only specially authorised devices and sensors that do not represent an ignition source even in the event of long-term exposure may be used here.
Areas in which explosive gases or vapours regularly occur during normal operation are classified as zone 1. This is the case, for example, in filling and emptying processes, in gas distribution or mixing systems or when transferring products between reactors and storage tanks. Devices must be designed in such a way that they do not cause ignition even if they come into frequent contact with an explosive atmosphere.
Zone 2 describes areas in which explosive gases, vapours or mists only occur briefly and irregularly, for example in the event of leaks or in the vicinity of compressors and pipe systems. Devices that work safely under normal operating conditions and do not represent a source of ignition even in the event of malfunctions are sufficient.
Zone 20 describes areas in which explosive dust atmospheres are constantly or frequently present, for example in silos or filter systems. The same strict requirements apply here as in Zone 0 for gases: all devices must be protected against dust deposits, heat development and electrostatic charging.
In Zone 21, an explosive dust atmosphere regularly occurs during normal operation, for example in filling systems, mixers or in the vicinity of discharge systems. Devices must be dust-proof and heat-resistant to prevent ignition.
Zone 22 covers areas in which explosive dust atmospheres occur only occasionally, e.g. in packaging, food or conveyor systems. Components used in this zone are reliably protected against dust and temperature increases under normal operating conditions.
Explosion prevention and protection in automation describes all technical and organisational measures that prevent ignition from occurring in systems with potentially explosive atmospheres. This includes the correct selection and certification of electric and pneumatic components, zoning and compliance with international directives such as IECEx or ATEX. This ensures that automated processes run safely, reliably and in compliance with standards, even in critical environments.
IECEx is an international certification system for devices and components used in potentially explosive atmospheres. It is based on IEC standards and ensures test procedures worldwide are standardised.
By harmonising different national regulations, IECEx facilitates market access and reduces the effort involved in international projects.
ATEX is the European directive for explosion prevention and protection (2014/34/EU). It regulates which devices and protective systems may be used in potentially explosive atmospheres in the EU. In addition to technical testing in accordance with IEC standards, ATEX also requires legal certificates and CE identification.
Details on the directive can be found under ATEX – European Directive.
IECEx is a global, voluntary certification system, while ATEX is the binding EU directive. Both are based on the same technical standards, but differ in their legal validity: ATEX is mandatory in Europe, IECEx is internationally recognised but optional.
Devices with both certifications can be used worldwide, as the associated test and safety requirements are clearly traceable in accordance with IEC standards.
IECEx certification is carried out by recognised test centres that test components in accordance with international explosion prevention and protection standards. Manufacturers must prove that their products are not an ignition source and can be operated safely in the long term. Approved certification bodies (ExCBs) document the results in a publicly accessible IECEx certificate.
Certification is always required when devices are used in potentially explosive atmospheres, i.e. where gas, vapour or dust atmospheres can occur. In Europe, ATEX is required by law, while IECEx is used internationally as proof of standardised safety. Certified components not only ensure operation, but also liability and legal compliance.
Explosion prevention and protection and functional safety (SIL) both pursue the goal of minimising risks in automation, but in different ways. Explosion prevention and protection prevents explosive atmospheres from igniting. SIL evaluates and reduces systematic or accidental malfunctions in safety-related controllers.
Further information can be found on our page on Functional safety (SIL) in the process industry.
Both areas are part of a comprehensive safety concept. Explosion prevention and protection protects systems and people from ignition hazards, while machinery safety protects them from mechanical or electrical risks.
Together, they help to assess and minimise risks and safeguard against them in accordance with standards.
You can find more detailed information on this topic on our website Machinery safety in automation technology.
ATEX and IECEx describe the explosion prevention and protection of electrical devices in explosive atmospheres, while IP protection classes determine their impermeability to dust and water. Both specifications complement each other, but address different safety aspects.