The safest cables for EX-applications.
Dr.-Ing. Edmund Remane, HRADIL Spezialkabel GmbH, R&D special projects
The new developed HRADIL SC 44 cables fulfill the requirements of the IEC 60079-14-9.3.1 in its entirety
Explosion prevention is a main preoccupation in many industrial production areas such as in chemical and petrochemical industries, oil- , gas extractions and mining; in these fields combustible gases and vapors are liberated throughout production, transport and storage.
HRADIL first solves the zone entrainment problem.
Because it is not possible to limit electricity and voltage in such a way that a spark formation could be a 100% avoided, one tries to prevent an explosion through higher components safety and flameproof encapsulation. Despite these preventions many accidents occurred due to the fact that explosive gases passed through the cable into less protected areas.
The IEC 60079-14-9 regulates the requirements of cables in EX applications relating to mechanical damages as well as to damages due to corrosion, chemical and thermic actions. Many suppliers comply with these requirements and make use of special thermoplastic materials and specific cable constructions.
But the contractual obligation of the IEC 60079-14-9.3.1 that a “pumping action” – means a zone entrainment - of explosive gases out of a potentially explosive environment must be inhibited, has been insufficiently fulfilled until now, mostly due to the fact that a cable structure is not entirely compact. Open spaces between cable wires and fillers may exist, in which the explosive gases flow in and spread. Given this capillary structure, a zone entrainment cannot be excluded. The risk is even higher when the cable contains hygroscopic porous fillers like flow tissues and fibrous materials.
HRADIL Spezialkabel has developed a new production process by which this contractual obligation of the IEC 60079-14 9.3.1 is fulfilled for a wide range of cables. Technical background is a special developed pressure-extrusion method, with which a flame-retardant, halogen and non-hygroscopic material mix is inserted within the cable. All cable cores and shieldings are embedded in such a way that all capillary spaces within the wire are filled. There is no way a zone entrainment of combustible gases may occur, as certifies the DEKRA test report.
Technical and legal consequences
HRADIL CEO Alfred Hradil emphasizes the safety gain that the new SC 44 cables offers: “This is the first time we can fully guarantee that a zone entrainment of easily combustible substances cannot occur with our cables. This is why these cables will have an enormous impact on all off-shore applications and on the chemical industry. For with these further developed and conformable state-of-the-art cables, all suppliers and producers can supply proof that they fully meet the requirements of the IEC 60079-14-9.3.1”.
All suppliers and producers in the EX fields have long known that the crucial point of the IEC 60079-14-9.3.1, the zone entrainment, could hardly be fulfilled. In practice though, this wasn’t a problem. Even if the „worst case“ happened, one could still refer to the latent residual risk given that the state of the art production process capabilities could not eliminate the possibility of a zone entrainment. The new HRADIL SC 44 cables now changed it all. The entire requirements of the IEC 60079-14-9.3.1 can be fulfilled, the state-of-the-art technology has been taken one step forward. For the benefit of all who work in explosion hazardous areas.
Background IEC 60079-14
Design, selection and erection of electrical installations in explosive atmospheres
This standard regulates the installation of electrical equipment in hazardous areas with explosive atmospheres due to gases and vapors. It replaces DIN VDE 0165:1991-02, except from its dust hazards sections which still are valid (until the EN 50281-1-2 (DIN VDE 0165 part 2) is implemented). It supplements the requirements of the general erection regulations of DIN VDE 0100ff and additional applicable standards.
The scope is extensively regulated. The standard applies for all electrical installations and equipment in hazardous areas, regardless if they are permanently or temporarily fixed, portable, transportable or being held in the hand. It applies for all electric voltages.