Standards and certification for hazardous area instrumentation. June 2015

This publication is based on an appendix written by Chris Towle BSc, CEng, MIMech.E, MIET, FInstMC

1. Introduction
This document is intended to provide guidance on the certification and standards used in the design and application of instrumentation used in hazardous areas. Inevitably this subject is one of constant but usually slow change and hence the date on which this document is written [June 2015] should be taken into account when considering any action based on this document.

All standards are created by individuals who have a specific interest in the subject. The time involved and the costs incurred by participants are considerable. This restricts the people involved to those with an enforcement, certification or commercial interest, which they tend to promote. Consequently the major representation on international committees is from certification bodies; manufacturers have adequate representation but end-users are not adequately represented. The resultant standards are reasonable and produce adequately safe equipment, which is surprising and a testament to the integrity of the individuals involved.

2. Standards organisations
2.1 IEC
International standards for electrical equipment are created by the International Electrotechnical Committee [IEC]. Those covering hazardous areas are created by a specific committee TC31 and its numerous sub-committees and form part of the IEC 60079 series. The process of creating and modifying standards is slow because of the lengthy but essential consultation process. An interval of five years between editions of the standards is quite common. Almost all national standards-making organisations are members of IEC and it is a truly international organisation.

The format of the IEC standard number is IEC 60079-xx: yyyy. The xx being the part number of the specific section and the yyyy the year of publication.

The European Committee for Electrotechnical Standardisation [CENELEC] are the European standards making body for electrical equipment. Currently IEC and CENELEC hazardous area standards are voted on simultaneously and bear the same number. The CENELEC committee on intrinsic safety exists but has not found it necessary to meet for several years. The standards are identical in technical content but the CENELEC standard contains further information to make it more useable with the ATEX directive. The apparatus standards are 'harmonised' as being an acceptable interpretation of the ATEX directive.

It is important to recognise that the directive is a European Union [EU] document not a CENELEC standard and hence introduces some minor differences. There is usually a time difference of several months between the publication of the IEC standard and the publication of the EN and its final 'harmonisation' so that it can be used for ATEX certification. This delay could lead to there being different requirements for IECEx and ATEX certification for a short time. However no significant problems have occurred as a result of these differences as far as is known to the author.

The CENELEC standard number [European Norm] is the same as the corresponding IEC standard and has the form EN 60079-xx: yyyy. The date of publication may be one year later than the corresponding IEC standard.

2.3 BSI
The British Standards Institution [BSI] is the United Kingdom participating member of both IEC and CENELEC. BSI publish an English language version of the CENELEC standard. The form of the standard number is BS EN 60079-xx: yyyy. The technical content of the IEC, CENELEC and BS standards are identical.

3. IECEx
The IEC has an affiliated organisation which issues certificates of compliance with the IEC 60079 Series of standards. [There are a number of other related activities]. These certificates are based on detailed test reports created by approved testing organisations and are granted to manufacturers with approved quality control systems. The organisation is based in Australia; it has a strong secretariat responsible to a committee controlled by the approved certification bodies [CB]. A major advantage of IECEx certificates is that the latest version is available on the web and hence can be consulted at any time. IECEx certificates can only be issued by CBs. Anyone can use the IEC standards as a basis for 'certification' but this does not create an IECEx certificate.

The intended ideal is for IECEx certificates to be accepted universally. Some progress has been made in this direction, for example in Australia and Singapore, and there has been considerable support from the relevant United Nations organisation. Numerous countries issue certificates based on the IEC test report but sometimes the acceptance is questioned in excruciating detail and other barriers to issuing the certificates erected. It can still be an irritating and expensive business. It is disappointing that IECEx certificates are not acceptable in Europe and the US There are some chinks in the US barrier, For example the U.S. Coastguard accepts some IECEx certification. In countries where the end-user decides what is acceptable then IECEx certificates are usually favoured. The usual practice of European manufacturers is to obtain an IECEx certificate and test report and use these to obtain an ATEX certificate. The only consolation is that the current situation is a considerable improvement on the late 1900s when everybody used different standards and their own specially defended single certification body.

IECEx Certificate and EU Declaration of Conformity
IECEx Certificate and EU Declaration of Conformity

It is difficult to be too definitive about where IECEx certificates are accepted because there does not appear to be an authorised list. Australia, New Zealand and Singapore are known to accept IECEx certificates. Brazil. China, Russia, Korea and India are known to issue local certificates based on the IEC test reports.