Comprehensive explosion protection tailor-made for complex production plants
In line with technical advancement the production procedures in the processing industries get increasingly perfected. In parallel they get increasingly more complex. This also counts for the explosion protection, if it is needed. Mastering all this requires experience and expert knowledge. Therefore comprehensive system solutions from single sources get very popular, especially as a great many diverse regulations and safety standards have to be respected. Pepperl+Fuchs supports plant operators all over the world with expert knowledge in explosion protection and turnkey system solutions.
An explosion happens in a fraction of a second and actually is a relatively simple chemical reaction. The safe prevention of this explosion, however, or at least the minimization of the dangerous consequences, is a complex task which requires profound knowledge and experience. The first IS interface barriers, introduced by Pepperl+Fuchs in the 1950‘s, originated the intrinsically safe explosion protection in process automation. Today the company is worldwide market leader for this technology. In parallel, huge development capacities have been invested in all other types of explosion protection so novelties and improvements got released to the markets continuously. The experts and engineers are active in many standardization organizations and technical committees, such as in shaping IEC 60079 which internationally defines the basic requirements for explosion protection. Its adaption for the European Union, until April 2016, was directive 94/9/EU (ATEX 95) which is now succeeded by directive 2014/34/EU. Further conformity assessment schemes are according to IECEx or specific national standards, for instance NEC500 and NEC505 in USA, the ‚Eurasian Conformity‘ (EAC) valid in the customs union Russia/Belarus/Kazakhstan, CCOE in India or NEPSI in China, just to name a few.
These standards define types of protection, zone classifications of hazardous areas as well as requirements on installation, maintenance and repair. Most types of protection require special design provisions on equipment and associated apparatus for use in hazardous areas. Among those are ‘increased safety’ Ex e (IEC 60079-7) and ‚intrinsic safety‘ Ex i (IEC 60079-11). Equipment not specifically designed for hazardous areas can be protected by means of ‚pressurized enclosure‘ Ex p (IEC 60079-2) or ‘flameproof enclosure‘ Ex d (IEC 60079-1). Protection against dust ignitions can be achieved by ‘protection by enclosure‘ Ex t (IEC 60079-31).
All these details on international, regional as well as company-internal safety regulations have to be aligned with the requirements of the specific processing application. Pepperl+Fuchs offers components in all aforementioned types of explosion protection as well as the expertise to combine these with further functionalities to application-specific solutions. In ordinary cases this is achieved by configurations from a pre-defined modular kit in a certain type of explosion protection. More complex requirements demand for sophisticated engineering, frequently combining various types of explosion protection as well as non-protected components. So-called Solution Engineering Centers (SEC) design the specific solution in close cooperation with the customer, manage the project from start through parts procurement and manufacturing to commissioning at the user’s site. The tailor-made systems integrate indigenous explosion protection modules with components from third-party providers, according to the customer’s specification.
For process control, intrinsically safe technologies are state-of-the-art: analog safety barriers, Remote I/O Systems or fieldbus topologies. ‚Intrinsic safety‘ Ex i allows to maintain or exchange field devices and signal transmission components without process shut-down. By limiting the power in each electrical circuit a possible arc or spark is kept below the ignition energy of the surrounding gas atmosphere. The consequence, however, is limited energy to feed loop-powered devices.
Components or devices not designed according to any type of protection which prevents the occurrence of sparks, have to be safely protected when used in hazardous areas. There are two options. ‚Pressurization‘ Ex p contains the potential ignition sources inside an appropriate enclosure and keeps any explosive gas mixture on the outside by means of overpressure. A continuous flow of inert gas must be guaranteed by reliable control and monitoring methods. ‘Flameproof’ Ex d, in contrast, contains a possible explosion inside sturdy enclosures without the need of active control elements and pumps. Suitably designed flame paths prevent the egression of the flame. Furthermore the outer surface of the enclosure must never reach the ignition temperature of the surrounding gas atmosphere.
Lighting or power distribution networks as well as control of machinery which requires more energy than possible with Ex i can be achieved by ‘increased safety’ Ex e. Several modular product series of terminal boxes, control units as well as complex control stations offer the most efficient solution for any specific application. The modular concept of Ex e certified components, from terminals, pushbuttons and LED indicators through control switches with various switching positions and contact configurations to potentiometers and measuring devices, in conjunction with several enclosure variants, allows a multitude of configuration options. Even buzzers can be integrated. Many functions are also available as individually equipment certified devices, allowing the user to design unique control panels with full certification.
Enclosures manufactured from aluminum, stainless steel, cast iron or glass fiber reinforced polyester form the base for any explosion protected solution. These are available in many different sizes and designs, with viewing windows for monitoring instruments as an option. Especially for Ex d enclosures the highest quality standards are valid, they are made of saltwater-resistant, copper-free aluminum or premium AISI 316L stainless steel.
With solutions incorporating non-certified components, be it in Ex p or Ex d, adherence to the relevant equipment standards is ensured by the project engineers in the SECs. Once in operation the user has to consider the regulations regarding testing, commissioning and maintenance of electrical installations in hazardous areas. These are defined in IEC 60079-14 and -17. Especially with Ex d special care is mandatory when working on the enclosure or closing the enclosure cover. Therefore a combination with a connection chamber in Ex e is convenient. Both enclosures are mechanically connected by a particular flange, specific line bushings are utilized for cable entry into the Ex d compartment.
Based on the huge variety of components and enclosures, both Ex e or Ex d, as well as Ex p control elements, the project engineers in close cooperation with the customer will derive the most efficient solution. Users will benefit from all types of explosion protection, in turnkey solutions tailored to their specific applications. Superior quality, comprehensive certification, detailed documentation as well as continuing support form the basis for efficient plant operation. Don’t hesitate to contact us.
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