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What Does ATEX Mean?
ATEX stands for "Atmosphères Explosibles" and refers to the European regulatory framework for equipment, machinery and protective systems used in potentially explosive atmospheres.
An explosive atmosphere forms when flammable gases, vapours, mists or dusts mix with air in sufficient concentration. A single ignition spark – for example from an unsuitable electric motor or an electrostatic discharge – can then trigger an explosion.
In everyday usage, the term "ATEX approval" is frequently used. However, the legally correct term is ATEX conformity assessment in accordance with Directive 2014/34/EU. There is no government "approval" in the strict sense – instead, the manufacturer demonstrates through a conformity procedure that the product meets the essential health and safety requirements. The result is CE marking with the additional Ex symbol.
When Is ATEX Conformity Required?
Not every piece of equipment in an industrial facility requires ATEX. The decisive factors are whether an explosive atmosphere exists and whether the equipment could constitute an ignition source.
Whether ATEX conformity is relevant for your installation can be determined using a simple decision logic:
- Combustible substances present? Are flammable gases, vapours, mists or dusts processed, stored or transported?
- Explosive atmosphere possible? Can an ignitable mixture of these substances and air form in work areas?
- Equipment as ignition source? Could the equipment in use cause ignition through sparks, hot surfaces, electrostatic charge or mechanical friction?
Only when all three conditions are met simultaneously is an ATEX conformity assessment in accordance with Directive 2014/34/EU required for the equipment. The operator's risk assessment under Directive 1999/92/EC forms the basis for this evaluation.
ATEX Quick Check
Answer three questions to find out whether ATEX conformity could be relevant for your installation.
Non-binding initial assessment – does not replace a risk assessment.
Are flammable gases, vapours, mists or dusts processed, stored or transported at your facility?
Can an explosive atmosphere form in hazardous concentrations in your work areas?
Is equipment used in these areas that could act as an ignition source (e.g. electric motors, sensors, switchgear)?
Without combustible substances, an explosive atmosphere generally does not form. An ATEX conformity assessment is most likely not necessary.
This quick check does not replace an expert risk assessment under Directive 1999/92/EC. The actual evaluation is the responsibility of the operator or a competent person.
Combustible substances are present, but whether an explosive atmosphere can actually form in hazardous concentrations should be evaluated by an expert risk assessment.
This quick check does not replace an expert risk assessment under Directive 1999/92/EC. The actual evaluation is the responsibility of the operator or a competent person.
Combustible substances, explosive atmosphere and potential ignition sources – in this combination, an ATEX conformity assessment under Directive 2014/34/EU is generally mandatory. The required equipment category depends on the EX zone classification.
This quick check does not replace an expert risk assessment under Directive 1999/92/EC. The actual evaluation is the responsibility of the operator or a competent person.
Equipment without its own ignition potential (e.g. purely passive vessels without electrics) may in certain circumstances be operated in EX areas without a dedicated ATEX conformity assessment. A risk assessment by the operator is still required.
This quick check does not replace an expert risk assessment under Directive 1999/92/EC. The actual evaluation is the responsibility of the operator or a competent person.
Which EU Directives Govern ATEX?
The ATEX regulatory framework is based on two EU directives: one for manufacturers (product requirements), one for operators (occupational safety). Both are closely interlinked.
2014/34/EU – The Product Directive (ATEX 114)
The Product Directive addresses manufacturers of equipment and protective systems intended for use in potentially explosive atmospheres. It defines the technical requirements a product must meet before being placed on the market:
- Conformity assessment: The manufacturer must demonstrate that the product meets the essential health and safety requirements – depending on the equipment category, through internal production control or with the involvement of a notified body.
- Technical documentation: Design documents, risk analyses and test reports must be complete and retained for at least ten years.
- CE marking and Ex symbol: Compliant products receive the CE marking along with the specific Ex symbol (hexagonal mark) indicating the relevant equipment category.
1999/92/EC – The Workplace Directive (ATEX 137)
The Workplace Directive addresses employers and operators of installations in potentially explosive atmospheres. It requires systematic protective measures:
- Risk assessment: Systematic evaluation of whether and where explosive atmospheres may occur.
- Zone classification: Classification of areas according to the frequency and duration of the occurrence of explosive atmospheres.
- Protective measures: Technical and organisational measures to prevent ignition sources and limit the effects of explosions.
- Explosion protection document: Written documentation of all assessments, zones and measures – must be available before work commences and kept up to date.
Risk Assessment as a Mandatory Basis
Before any equipment may be used in a potentially explosive area, the operator must assess whether and how frequently an explosive atmosphere may occur. The result of this assessment determines the EX zone and thus the permissible equipment category. Without a documented risk assessment, operating installations in potentially explosive areas is not permitted.
EX Zones at a Glance: Zone 0, Zone 1 and Zone 2
Zone classification categorises areas according to the frequency and duration of the occurrence of explosive atmospheres. It determines which equipment category may be used.
The following overview refers to gas and vapour atmospheres (identifier G), which are typically relevant for mixing vessels. For dust atmospheres, the analogous Zones 20, 21 and 22 (identifier D) apply.
| Zone | Frequency of explosive atmosphere | Typical occurrence | Permitted equipment category |
|---|---|---|---|
| Zone 0 | Continuously, for long periods or frequently | Interior of vessels containing flammable liquids | Category 1G only |
| Zone 1 | Occasionally during normal operation | Near vents, filling points, manhole openings | Category 1G or 2G |
| Zone 2 | Rarely and only for short periods | Near pipe connections, safety valves, flange gaskets | Category 1G, 2G or 3G |
For stainless steel mixing vessels, Zone 0 typically applies inside the vessel when flammable media are processed. The immediate external area around filling and venting openings is usually classified as Zone 1, while more distant areas are classified as Zone 2.
Which ATEX Category Belongs to Which Zone?
The assignment of equipment categories to EX zones is normatively defined. If you know your zone, you can directly determine the minimum required equipment category.
The following table shows the assignment for gas/vapour atmospheres (G) and dust atmospheres (D):
| Zone (Gas / Dust) | Atmosphere | Minimum required category |
|---|---|---|
| Zone 0 / Zone 20 | Present continuously or for long periods | Category 1 (highest protection level) |
| Zone 1 / Zone 21 | Occasionally during normal operation | Category 2 |
| Zone 2 / Zone 22 | Rarely and only for short periods | Category 3 |
A higher equipment category may always be used in a lower zone: a Category 1 device is also permissible in Zone 1 and Zone 2. The reverse does not apply – a Category 3 device must not be operated in Zone 0 or Zone 1.
How to Read ATEX Marking Correctly
Every ATEX-compliant device bears a standardised marking. Understanding the individual components allows you to directly assess whether a device is suitable for a specific zone.
ATEX marking follows a fixed scheme. Using the example of a typical agitator drive for Zone 1:
Example marking: II 2G Ex IIB T4 Gb
- II – Equipment group II: Equipment for all industrial sectors except mining (Group I). Virtually all agitators and vessel components fall into Group II.
- 2G – Equipment category 2, gas/vapour: Approved for Zone 1 (and Zone 2). The number indicates the protection level (1 = highest, 3 = lowest), the letter indicates the atmosphere (G = gas, D = dust).
- Ex – Explosion protection: Identifies the equipment as tested for use in potentially explosive atmospheres.
- IIB – Gas group: Classifies the ignitability of the gases for which the equipment is designed. IIA = low ignitability (e.g. propane), IIB = medium (e.g. ethylene), IIC = high (e.g. hydrogen, acetylene).
- T4 – Temperature class: Maximum surface temperature of the equipment during operation is 135 °C. The ignition temperature of the medium must not fall below this value.
- Gb – Equipment Protection Level: "Gb" indicates a high level of protection – the equipment provides protection against ignition even under foreseeable malfunctions.
When procuring agitators and vessel components, the marking must be matched against the zone classification and the medium being processed. The gas group and temperature class in particular must suit the specific application.
Common Misconceptions About ATEX
There are widespread misconceptions surrounding ATEX. Knowing them helps avoid unnecessary costs and legal risks.
Misconception: "Every device in an EX zone requires ATEX"
- ATEX only applies to equipment that could itself constitute an ignition source. Purely passive components without electrical, mechanical or thermal ignition potential – such as simple pipe sections or closed storage tanks without attachments – are not automatically subject to ATEX requirements.
Misconception: "Passive vessels are automatically subject to ATEX"
- A stainless steel vessel without its own active components (no motor, no sensors, no electrics) is not in itself classified as "equipment" within the meaning of Directive 2014/34/EU. However, as soon as an agitator, heater or instrumentation is fitted, the assessment changes for these components.
Misconception: "Once ATEX-compliant, always ATEX-compliant"
- Modifications, retrofits or the replacement of components can invalidate existing conformity. After every significant change, the conformity assessment must be re-examined and documented.
Important: The operator bears co-responsibility
- ATEX conformity of a device alone is not sufficient. The operator is responsible for the risk assessment, correct zone classification, the explosion protection document and the selection of suitable equipment. These obligations are regulated in Directive 1999/92/EC.
ATEX vs. CE – What Is the Difference?
Many users confuse ATEX conformity with general CE marking. Both have different scopes of application.
- CE marking: Indicates that a product meets the fundamental requirements of all applicable EU directives (e.g. Machinery Directive, Low Voltage Directive, EMC Directive). CE marking is mandatory for virtually all products placed on the EU single market.
- ATEX conformity: Is an additional requirement for equipment and protective systems used in potentially explosive atmospheres. It is governed by Directive 2014/34/EU and applies in addition to the general CE marking.
A device with CE marking is therefore not automatically approved for use in EX areas. Conversely, every ATEX-compliant device also bears the CE marking – plus the additional hexagonal Ex symbol indicating the equipment category.
Practical Example: Agitator in a Stainless Steel Vessel
In the chemical industry as well as in food, beverage and pharmaceutical production, stainless steel mixing vessels are used in potentially explosive areas. ATEX conformity applies to all active components.
Stainless steel is widely used as a material for vessels in EX areas: it is corrosion-resistant, hygienic and easy to clean. However, the material alone is not sufficient – in potentially explosive areas, all active components of a mixing vessel must be designed with explosion protection:
- Agitator and drive motor: The motor must be approved for the respective zone (e.g. Category 2G for Zone 1). The agitator shaft and bearings must not create ignition sources through friction or overheating.
- Sealing systems: Mechanical seals or magnetic couplings prevent the escape of flammable media. The seal itself must be ATEX-compliant.
- Instrumentation and sensors: Temperature, pressure and level sensors must be provided in intrinsically safe design (Ex i) or in flameproof enclosure (Ex d).
- Earthing and equipotential bonding: All metallic components must be continuously earthed to eliminate electrostatic charge as an ignition source.
Typical zone configuration for a closed mixing vessel: Zone 0 inside the vessel, Zone 1 or Zone 2 in the immediate external area around manholes, filling nozzles and vents.
ATEX conformity required for
- Agitators and drives in vessels with flammable media
- Electrical components in areas with gas, vapour or dust atmospheres
- Instrumentation and sensors within classified EX zones
- Sealing systems at vessel openings in potentially explosive areas
ATEX conformity generally not required for
- Vessels and agitators operated exclusively with non-flammable media
- Installations in areas without a classified EX zone
- Purely mechanical components without their own potential ignition source (subject to risk assessment)
Used EX vessels are a cost-effective alternative, provided condition, documentation and marking are current and complete. Behälter KG stocks inspected stainless steel mixing vessels as well as explosion-protected mixing vessels.
Tips for Selecting and Operating ATEX Mixing Vessels
The correct selection and safe operation of agitators in EX areas require a systematic review of several factors – from zone classification to documentation.
- Determine the zone: Establish the EX zone for the installation location based on the risk assessment. The zone determines the required equipment category.
- Check all components: Not only the drive motor, but also seals, instrumentation, lighting and electrical connections must be checked for ATEX conformity. Every component must be approved for the respective zone.
- Ensure earthing and equipotential bonding: Continuous earthing of all metallic parts is mandatory. Missing or interrupted earthing connections are among the most common deficiencies found during inspections.
- Match medium and temperature class: The gas group (IIA/IIB/IIC) and temperature class (T1–T6) of the equipment must match the medium being processed. The ignition temperature of the medium must be above the maximum surface temperature of the equipment.
- Maintain complete documentation: EU declaration of conformity, explosion protection document, test certificates and maintenance records must be available and up to date. For used installations: check documentation before purchase.
- Evaluate used installations: Used ATEX vessels and agitators are technically suitable when the marking is legible and correct, documentation is complete, and the technical condition is confirmed by an expert inspection.
