Should a machine working with combustible gas or dust be ATEX-marked? The answer is… it depends.
Article 1 of Directive 2014/34/EU defines that it applies to:
- equipment and protective systems intended for use in potentially explosive atmospheres;
- safety, control and regulating devices intended for use outside potentially explosive atmospheres but necessary or useful for the safe functioning of equipment and protective systems with respect to the risks of explosion;
- components intended for incorporation into equipment and protective systems referred to in point a)
This implies that machinery that physically enters an atmosphere classified according to Directive 99/92/EC (zones 0, 1, 2, 20, 21, 22) must be ATEX-marked in accordance with the Directive (Art. 1, para. a)).
Machines that do not enter classified zones but which, by their design, constitute emission sources (and thus classify the zone in which they are installed) must also be ATEX-marked.
Non-ATEX machines, on the other hand, represent a large number of cases on the market. Think of dispensers for alcohol-based flavourings in the food industry, dispensers for flammable paints and/or solvents, and dispensers for combustible powders.
These machines may have leaks of liquids, vapours or dusts capable of forming potentially explosive atmospheres. When it is necessary to avoid the ATEX conformity process for such machines, explosion prevention systems can be used: ventilation, dilution, confinement of atmospheres in such a way as to reduce the probability of ATEX formation to negligible values.
These systems represent safety functions within the meaning of requirement 1.5.7 of Directive 2006/42/EC, and as such must exhibit the appropriate level of reliability in terms of functional saftey. However, these functions are also covered by Article 1(b) of Directive 2014/34/EU.
Therefore, explosion hazard safety functions in non-ATEX machines must be ATEX functions, and all components in the logic chain (input-logic-output) must be ATEX-marked. As these components are not in a classified zone, they can be of the least economically impactful group (i.e. II 3GD); however, they must meet the required reliability requirements (PL or SIL).
Directive 2014/34/EU does not require marking of interior areas. This is because only external parts can come into contact with explosive atmospheres.
If a machine can exclude the release of hazardous substances inside it, the application of the ATEX Directive is not required. Possibly, the manufacturer can assign an internal classification for reasons of user information (e.g. isolators in which the user can insert objects, substances and equipment). In any case, the Machinery Directive already covers the explosive risk and requires that machines placed on the market comply with this aspect as well.
At Advolo, we provide a team of experts who can help you with the design and evaluation of ATEX products in compliance with national and international standards. Please do not hesitate to contact us for more information at: commerciale@advolo.it
