The ATEX guideline is intended to protect persons who work in potentially explosive atmospheres or who may be affected by explosions. The employees have to strictly observe the essential health and safety requirements by the manufacturer and certify that by means of conformity assessment procedures. The ATEX directive applies to explosion-proof, electrical and mechanical devices, components and protective systems. Only these may be used in potentially explosive atmospheres since 1 July 2003. In Germany, the Explosion Protection Product Ordinance transposed the EU directive into national law.
When handling substances that react with oxygen, there is a risk of explosion if it is in a room volume with a certain partial pressure or as fine-grained dust in the air. It is an explosive gas-air mixture when the fraction of flammable gas or a vaporized liquid is between the upper and lower explosive limit. Distributing flammable substances in the air can create an explosive atmosphere.
Explosion triangle: Combustible material, oxygen and ignition source cause an explosion
Primary explosion protection: Avoid explosive atmospheres
Secondary explosion protection: Avoid effective sources of ignition
Tertiary explosion protection: Constructive explosion protection
A classification of devices that can be used in potentially explosive atmospheres has been divided into three groups since the introduction of EN 60079-0: 2009.
Firedamp threatened mines
- depending on explosive substance
- Hazards increase from A to C
Explosive gases of some types of protection (EX i, EX d, Ex n) are subdivided into the following subgroups:
Dusts are divided into
Ex d = Pressure proof encapsulation
Ex n = depending on type, Ex nA, Ex nL or Ex ic
Subgroup A: gasoline, diesel, ethane
Subgroup B: town gas, ethylene, hydrogen sulfide
Subgroup C: hydrogen, carbon disulfide
If a system is operated in accordance with ATEX 137, approved inspection bodies have to regularly inspect it in accordance with the operational safety ordinance. Qualified persons have vocational training, experience and have recently done the job to have the necessary specialist knowledge. Devices must completely prevent the ignition of explosive atmospheres or at least reduce the effect to a sufficient safe level. In Germany, the TÜV Süd tests the systems.
When products require a production control, a notified body gives them the CE marking. It applies to devices or systems with an EC-Type Examination Certificate issued by a notified body (electrical equipment 0, 20, 1, 21 incl. internal combustion engines) and mechanical equipment for zones 0, 20.
Devices and protective systems covered by the directive require a CE marking, an EC declaration of conformity (confirmation of compliance with essential health and safety requirements) and a conformity assessment procedure. Only in this case products may be available for payment or free of charge on the EU market.
TBH also offers systems for extraction from explosion-proof areas (except mining). The devices comply with the applicable ATEX product guideline 2014/34 / EU and the standard DIN EN 1127-1: 2007. Systems of a category may only be used for certain zones, e.g. Category 2 devices are only permitted for zone 1 (for gases and vapors) or for zone 21 (dusts).
To ensure the correct extraction, the following questions must be answered:
- What is extracted?
- How much is released?
- Can the released amount be reduced?
- How is the contaminated air detected?
- Are there any fixed ATEX zones or other regulations?
- Is there an ignition hazard analysis and is it necessary?
From these findings, the operator determines the zones in his production. For this purpose, an ATEX consulting service provider can be used. This can also create an explosion protection document. If the risk has been assessed by the released substances and the zones have been classified, the appropriate extraction system can be selected. For this, TBH employees check the process parameters (dust or gas quantity, acquisition, required air volume flow, etc.) and the zone classification of the customer.