ATEX - equipment for potentially explosive atmospheres
Equipment and protection systems in potentially explosive atmospheres must be safe. The manufacturer of equipment and protections systems used in potentially explosive atmospheres is responsible for ensuring that the equipment or protection system meets the requirements laid down in the Directive on ATEX equipment.
The Directive on ATEX equipment regulates the safety of equipment and protection systems for potentially explosive atmospheres. ATEX comes from the French words “atmosphères explosibles”.
The purpose of the Directive on ATEX equipment is to ensure that ATEX products in use and on the market are safe for persons, domestic animals and property. ATEX products must be safe in their intended purpose of use and anticipated disruptions, and their structure must not allow explosive mixtures of air to ignite.
What are potentially explosive atmospheres?
Potentially explosive atmospheres are conditions that potentially contain an explosive mixture of air. The potentially explosive mixture of air may be caused by flammable gases, mists, vapours or dust when mixed with air.
Potentially explosive atmospheres primarily occur when handling flammable liquids and gases, and dusts, in the processing industry and distribution substations, for example.
Scope of application of the Directive on ATEX equipment
The Directive on ATEX equipment applies to equipment intended for use in potentially explosive atmospheres, including
- electrical and mechanical equipment with an ignition source;
- protective systems;
- components of equipment and protective systems;
The scope of application also includes safety, regulating and control equipment that is intended for use outside the potentially explosive atmospheres but is necessary for the safe operation of equipment and protection systems or that reduces the risk of explosion.
The scope of application of the Directive on ATEX equipment excludes
- medical devices;
- means of transport;
- seagoing vessels;
- personal protective equipment;
- equipment and protective systems where the explosion hazard results from the presence of explosive substances or unstable chemical substances;
- equipment intended for use in domestic and non-commercial environments where potentially explosive atmospheres may only rarely be created, solely as a result of the accidental leakage of fuel gas;
- simple equipment and equipment whose sole potential source of ignition is static electricity caused by the process;
Classification of products
The manufacturer must define the ATEX equipment’s group and category based in its purpose of use.
The Directive divides equipment into two groups based on where the equipment is used:
- group I products are intended for use in the underground parts of mines and in those parts of surface installations of such mines that are likely to become endangered by firedamp and/or combustible dust;
- group II products are intended for use in other environments that are likely to become endangered by explosive atmospheres.
The groups are divided into equipment categories. Products in group I are divided into two equipment categories: M1 and M2 and products in group II are divided into three equipment categories: 1, 2 and 3. For group I, one of the factors that the categorisation is based on is whether the product becomes de-energised in the event of an explosive atmosphere. Products in group II are categorised based on where the product’s intended place of use is, i.e. is the atmosphere always potentially explosive or is it likely to occur for short or extended periods. Further information on the categorisation of products is available in Annex I of the Directive on ETAX equipment.
Safety, regulating and control equipment is categorised based on the equipment or protection system for the operation of which they are necessary and to the operation of which they contribute.
|Level of protection||Group I||Group II||Efficiency of protection||Operating conditions|
|Very high||M1||Two independent means of protection or protection assured in the event of two faults occurring independently of each other.||The equipment remains energised and operational in an explosive atmosphere.|
|Very high||1||Two independent means of protection or protection assured in the event of two faults occurring independently of each other.||The equipment remains energised and operational in atmosphere categories 0,1,2 (G) and/or 20,21,22 (D)|
|High||M2||Normal operation and severe operating conditions||The equipment de-energises in the event of an explosive atmosphere|
|High||2||Normal operation and anticipated frequently occurring disturbances or equipment faults.||The equipment remains energised and operational in atmosphere categories 1,2 (G) and/or 21,22 (D)|
|Normal||3||Normal operation||The equipment remains energised and operational in atmosphere categories 2 (G) and/or 22 (D)|
Obligations of the manufacturer, importer and seller
Miten ilmanvaihto vaikuttaa tilaluokitukseen?
Ilmanvaihto on edellytyksenä tilaluokitukselle.
- Ilmanvaihdon vaikutus tilaluokitukseen
- arvioidaan erikseen saatavuus ja teho (esim. ulkona ilmanvaihto on aina saatavilla, mutta teho vaihtelee)
- Ilmanvaihdon poistojen sijoitus kaasun ominaisuuksien mukaan (palavan nesteen höyryt ilmaa raskaampia, vety ilmaa kevyempää)
- Alipaine suhteessa ympäröiviin tiloihin
- Normaalin toiminnan aikana palavan nesteen höyryjä => oltava koneellinen ilmavaihto
- Pitoisuus ilmassa ≤ 25% alemmasta syttymisrajasta
- Ilmanvaihdon riittävyyttä tulee valvoa eli käytännössä mitattava
Ilmanvaihtokanavat ja -aukot on puhdistettava riittävän usein.
- Ilmanvaihdon vaikutus tilaluokitukseen
Responsibilities of the manufacturer, importer and seller in table format
Operating instructions and markings regarding the safe use of products