On the Subject of Hazardous Applications
For more than 50 years, Knick has developed and produced hazardous-area equipment with the intrinsic safety type ‘i’ protection preferred by the chemical industry. The product range of approved equipment includes standard-signal isolators, repeater power supplies and temperature transmitters as well as devices for liquid analysis, systems for fully automated process analysis and retractable fittings. The approvals are in line with IECEx standards, ATEX rules and, for North America, UL, FM, and CSA, as well as further regional standards.
The intrinsic safety type of protection ‘i’ is based on the limitation of voltages and currents or power outputs in order to reliably avoid explosive sparking or impermissible heating. The maximum permissible values were determined in comprehensive test series carried out by the German PTB and other institutes and were first specified in according standards. The European standards EN 60079, EN 61241, and EN 13463 currently serve as a basis for the development of explosion-protected equipment. The latest guidelines and regulations on the subject of explosion protection are always promptly implemented by Knick and continuously integrated into the development of equipment.
Explosion protection has developed dynamically in recent years; this will continue in the future. A great deal of work in this respect has been and is being done by the International Electrotechnical Commission IEC, which also developed the series of standards
– IEC 60079 “Electrical apparatus for explosive gas atmospheres”
– IEC 61241 “Electrical apparatus for use in the presence of combustible dust”,
which now serve as the global basis of national standards.
In Europe, the 94/9/EC directive requires comprehensive explosion protection for electrical and nonelectrical equipment. This requirement was carried out when the above IEC standards became EN standards – further complemented by EN 13463 “Non-electrical apparatus for use in hazardous locations.” A range of changes have been added to the current bodies of standards; the following presents just a few examples of these:
– intrinsic safety “i”, introduction of type of protection ic in addition to ia, ib
– encapsulation “m”, division into types of protection ma, mb, mc
– introduction of Group III for dust atmospheres at risk of explosion, subdivided into IIIA, IIIB, IIIC
– introduction of information on EPL (Equipment Protection Level) Ga, Gb, Gc for gas and Da, Db, Dc for dust
Directive 94/9/EC also requires that “the latest technical level of knowledge, which is constantly changing, must be used promptly and as far as possible.” The assumption here is that the latest standards also reflect the latest technology. Equipment must therefore be regularly adapted to the latest body of standards. The standards themselves are usually reviewed every 3 to 5 years.
As every device is subject to several standards which naturally cannot all be superseded at the same time, the manufacturers must constantly work on revising their devices. This can mean that the identifier, the area of application, or the electrical data change. For this reason, users should check on every repeat order whether the relevant devices still meet their requirements.
Protection of existing rights continues to apply for existing systems and devices used within them.
Explosion protection continues to develop not just within the European Union but also on a global scale. Standardization of norms is seen as a particularly relevant factor here, making approvals valid in many countries. The desired ideal condition is a single, globally applicable approval. A system like this does exist, building on the IEC norms, and is generally known as the IECEx system. Although many countries cooperate on this system, the IECEx approvals themselves are still only accepted by a few nations. However, in countries which do not recognize the IECEx approvals, national approvals on the basis of the IECEx approvals are possible.
As a result, electrical equipment is increasingly first receiving an IECEx Certificate of Conformity (IECEx CoC) approval as per the IECEx standard. On the basis of this, approvals for the ATEX region, North America, Asia etc. are then carried out (IECEx CoC are available at www.iecex.com).
The IECEx standards are established on a zone system which will become the norm throughout the world. The division system common in the U.S. and Canada will nevertheless remain in force for a while – especially in the U.S., where new plants may still be built on this system. Both systems – the zone and the division system – have to date been used on a mutually exclusive basis in the U.S. and Canada; a mixture is not permissible.
Hazardous-area Quality Assurance Systems
Quality assurance systems for hazardous areas are required by the various approval systems / offices for the development and/or manufacture of hazardous-area devices. Compliance with the relevant standards is checked in regular audits. For example, the audits for IECEx and ATEX take place every three years, with an interim audit after half this time in each case. FM, CSA, and UL audit the parent plant and production sites every three months.