Installing non-certified equipment in hazardous areas with potential for gas explosion
05 December 2014
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 must be followed.
The Pepperl+Fuchs Bebco EPS Type X purge system reduces the classification within the protected enclosures from Division 1 to non-hazardous
An introduction to explosion protection rules and regulations
Three major explosion protection directives and standards 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: pressurisation Ex p (IEC 60079-2) and flameproof encapsulation Ex d (IEC 60079-1). As an expert on all explosion protection methods, Pepperl+Fuchs provide standard and customised solutions for both protection types:
Pressurisation (Ex p) keeps the explosive gas away from the equipment by creating an overpressure inside the enclosure. Visit www.pepperl-fuchs.co.uk/purge for more details on this specific topic.
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.
Comprehensive product tests ensure maximum security for applications with enclosures being thoroughly evaluated and tested during design, certification and production processes, to ensure the following requirements are fulfilled:
• The enclosure must withstand the explosion pressure without any damage
• Surface temperature must always stay below the ignition temperature of the surrounding atmosphere
• Any flame escaping through the gaps must cool down sufficiently
The pressure test is one of the rigorous examinations which ensure 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.
All Exd enclosure solutions are supplied from our 60,000 sq ft UK manufacturing facility in Birmingham to Pepperl+Fuchs world renowned high standard of ISO9000 certified quality and reliability. In addition, our unparalleled service provides expert application analysis and technical expertise at no extra charge with each and every product we manufacture.
For information on flameproof solutions please visit www.pepperl-fuchs.co.uk/flameproof.
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