Do you have a piece of equipment which you need to use in gas explosion hazardous areas but it is not designed for any type of explosion protection? On the surface, the solution seems fairly simple – you just put it into a protective housing. But since we are dealing with risks to human life and the environment, many rules have to be followed.
Three major explosion protection rules systems are important within the European Community:
Directive 99/92/EC (ATEX 137) “Minimum requirements for improving the health and safety protection of workers potentially at risk from explosive atmospheres” defines the responsibilities of the employer.
Directive 94/9/EC (ATEX 95) describes the rules for “manufacturing equipment and protective systems for use in potentially explosive atmospheres”.
In terms of standards, IEC 60079 covers most of the aspects to be considered. It contains the classification of hazardous areas (IEC 60079-10), the various types of protection, and maintenance and repair (IEC 60079-17 & -19).
This international standard is released into European and national rules, while additional regional regulations may apply.
The IEC standard offers two options to operate non-explosion protected equipment inside explosion hazardous areas: pressurization Ex p (IEC 60079-2) and flameproof encapsulation Ex d (IEC 60079-1). As an expert on explosion protection, Pepperl+Fuchs provides special solutions for both protection types.
Pressurization Ex p keeps the explosive gas away from the equipment by creating an overpressure inside the enclosure. The equipment stays safe, but continuous activities are required, such as maintaining the overpressure and monitoring in order to switch to safe conditions in case of malfunctions or external influences.
Flameproof encapsulation Ex d is, in comparison, “only” a passive enclosure with a certain ingress protection degree according to EN 60529. The explosive gas will enter the enclosure via the gaps at lid and cable entries. An explosion might take place inside but it must never come out.
Enclosures are thoroughly tested during certification and production process to ensure that an explosion never will come out. The following requirements have to be fulfilled by the enclosures:
The pressure test is one of the rigorous examinations which ensures that all of the mentioned requirements are met. Depending on enclosure volume, type of gas, and expected ambient temperatures, explosion reference pressures are determined. Each solution has to withstand these references.
Full certification of enclosure and operators such as switches, indicator lights, and pushbuttons, and the deep knowledge and experience of the project engineers in our Solution Engineering Centers ensure that your equipment will work optimally and your application will be safely protected.
For information on flameproof solution alternatives as well as engineering and customizing specifics please contact us or visit www.pepperl-fuchs.com/flameproof.