IEC Releases Standard for Safety of Electrical Equipment Used in Explosive Atmospheres - IEC 60079-1
June 8, 2007 // Published as a news service by IHS
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The International Electrotechnical Commission (IEC) developed IEC 60079-1 ed. 6 - Explosive atmospheres - Part 1: Equipment protection by flameproof enclosures "d" in response to accidents that occur when people work with explosive materials.
Published in April 2007, the standard recognizes that certain kinds of electrical equipment such as lamps, motors and electromagnets have the potential to produce sparks or other flames that could ignite explosive atmospheres.
The safety challenge for manufacturers of such equipment is to design enclosures that would contain any such flames and thus prevent them from causing the atmospheres to explode.
The standard provides specific guidelines for the construction and testing of equipment meant to operate in explosive atmospheres, which can be found in places as remote as floating oil rigs or in places as familiar as the neighbourhood petrol or filling station.
While considered the oldest of explosion protection techniques, the updated version of this standard incorporates the latest safety principals in equipment protection with flameproof enclosures known in the industry as "Ex d."
It was prepared by IEC Technical Committee (TC) 31, whose area of responsibility is equipment for use where there is a hazard due to the possible presence of explosive atmospheres of gases, vapours, mists or combustible dusts.
"There are things that go bang and there are things that make it go bang," said George Thompson, secretary to TC 31. "Keeping those two things apart is what it's really about."
"This standard addresses a protection technique that requires an enclosure to contain arcing parts (electrical discharges) under strict design and performance specifications," said Paul Kelly of UL Conformity Assessment Services and a member of TC 31.
"According to these strict specifications, an enclosure is to withstand the ignition of a gas atmosphere that may exist inside the enclosure, while also cooling any gases expelled from the enclosure as a result of the internal ignition. This cooling helps minimize the potential for ignition of any external explosive atmosphere that may surround the enclosure."
Another reason for manufacturers to employ the standard is to facilitate exports so that importers do not have to retest the equipment to ensure that it is safe, according to IEC Technical Officer Peter Lanctot.
A manufacturer holding a certificate issued by an IECEx Certification Body (ExCB) in the IECEx scheme will find it faster and cheaper to export into new markets, said the IEC. An up-to-date listing of approved certification bodies, which can issue IECEx Certificates of Conformity, can be found at www.iecex.com .
The sixth edition of IEC 60079-1 replaces the fifth edition, which was published in 2003.
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Technical changes from the previous edition include changes to critical dimensions, testing and marking requirements and to the determination of maximum surface temperatures and explosive pressures. The sixth edition also contains general revisions and a new annex regarding protection levels for explosive equipment.
Source: International Electrotechnical Commission (IEC).