Pixavi focuses on the following standards in order to achieve world wide certification:

• IECex (International)
• ATEX (Europe, but with International acceptance to some degree)
• FCC / CE (EMC, ESD and RF compliance)

 

Background

Explosive atmospheres can be caused by flammable gases, mists or vapours or by combustible dusts. With a certain level of concentration of these substances, all that is needed is a source of ignition to cause an explosion.

 

Explosions can be lethal and cause serious injuries as well as material and economic damage. Preventing releases of hazardous substances, which can create explosive atmospheres, and preventing sources of ignition are two widely used ways of reducing the risk. Using ATEX or IECex certified equipment is one way of doing this.

 

What is ATEX?

ATEX is the name commonly given to the framework for controlling explosive atmospheres and the standards of equipment and protective systems used in them. It is based on the requirements of two European Directives.

It is based on the requirements of two European Directives.

 

1) Directive 99/92/EC (also known as ‘ATEX 137’ or the 'ATEX Workplace Directive’) on minimum requirements for improving the health and safety protection of workers potentially at risk from explosive atmospheres. The text of the Directive and the supporting EU produced guidelines are available on the EU-website. For more information on how the requirements of the Directive have been put into effect in Great Britain see the information in the section on Equipment and protective systems intended for use in explosive atmospheres.

• ATEX Workplace Directive or Atex 137

 

2) Directive 94/9/EC (also known as ‘ATEX 95’ or ‘the ATEX Equipment Directive’) on the approximation of the laws of Members States concerning equipment and protective systems intended for use in potentially explosive atmospheres. The text of the Directive and EU produced supporting guidelines are available on the EU web site. For more information on how the requirements of the Directive have been put into effect in Great Britain see the section on Selection of equipment and protective systems.

• ATEX Equipment Directive

 

Equipment and protective systems intended for use in explosive atmospheres

The aim of Directive 94/9/EC is to allow the free trade of ‘ATEX’ equipment and protective systems within the EU by removing the need for separate testing and documentation for each Member State. In Great Britain, the requirements of the Directive were put into effect through the DTI’s Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 (SI 1996/192). The Regulations apply to all equipment intended for use in explosive atmospheres, whether electrical or mechanical, and also to protective systems. Manufacturers/suppliers (or importers, if the manufacturers are outside the EU) must ensure that their products meet essential health and safety requirements and undergo appropriate conformity procedures. This usually involves testing and certification by a ‘third-party’ certification body (known as a Notified Body), but manufacturers/suppliers can ‘self-certify’ equipment intended to be used in less hazardous explosive atmospheres. Once certified, the equipment is marked by the ‘EX’ symbol to identify it as such. Certification ensures that the equipment or protective system is fit for its intended purpose and that adequate information is supplied with it to ensure that it can be used safely.

The DTI has policy responsibility for the Regulations (although HSE enforces them).

 

What is IECex

The IECEx Scheme is an international Conformity Assessment Scheme covering Electrical Equipment for Explosive Atmospheres, as the Internationally accepted means of demonstrating conformity with IEC Standards prepared by IEC TC31

 

 

IECex vs ATEX

The new IECEx certification scheme helps manufacturers with a method of providing global acceptance for their hazardous area products in countries participating in the scheme.

 

ATEX is relying on many different forms of Conformity Assessment while IECEx is a true Type 5 Certification Scheme.  They each have their role, but which gives the greater confidence in the product?

 

Although both schemes relate to confirming the perceived safety of products for use in hazardous areas, their origins and the forces driving the way they operate are different.

 

ATEX is about enabling to trade within Europe.  Its purpose is to establish a level of safety which is to be regarded as sufficient to ensure that national authorities would accept the equipment certified.  It is not intended to help European equipment manufacturers to export to the rest of the world.  In pursuit of the removal of trade barriers, ATEX 94/9/EC eased off on some of the requirements in the previous ATEX directives (76/117/EEC and 82/130/EEC).

 

IECEx is about giving confidence that a product or service meets clearly defined transparent criteria.  By providing that transparency with a high level of confidence, it is intended that it will eventually provide a worldwide recognised certificate in which the whole world has confidence.  The driving force is safety, with the trade benefits following from the confidence.

 

IECEx is about to give confidence that a product or service meet clearly defined criteria. By providing transparency with a high degree of confidence, it would provide a certificate recognized globally.

 

The scope of the IECEx Scheme is defined by the standards issued by IEC Standards Committee TC 31 and is limited to electrical equipment, whereas the scope of ATEX is broader, also including non-electrical equipment and protective systems. Directly comparing the schemes is not relevant for equipment out of the scope of one of them, but note that there is an intention to broaden the scope of the IECEx Scheme in the future.

 

Use of standards

ATEX compliance is not about compliance with standards but about compliance with the Essential Health and Safety Requirements (EHSRs) given in the directive.  Because these are fairly general and not themselves subject to routine amendment or revision, the directive relies on standards to outline the norm in respect of the EHSRs.  However, since compliance with the standards is not required, it is impossible to tell from publicly available ATEX documentation the exact provisions that have been applied to a particular equipment. Standards are, however, very relevant in determining the norm.  It is an absolute requirement of the directive that changes in technological knowledge should be adopted as soon as practicable and the best guide to the commonly accepted state of such knowledge is contained in the harmonised standards.  It is even common to be ahead of the harmonisation process, though this should only be done in conjunction with a Notified Body that is active in the standards harmonization and is aware of all the implications.

 

Atex: Declaration of conformity

The single public domain document for ATEX is the manufacturer’s Declaration of Conformity (DoC).  This is the only document that the manufacturer is obliged to show to his customer and the manufacturer has sole responsibility for it.  He produces it entirely independently of any other documentation that he might have, although it may refer to other documentation.  In particular, it is the manufacturer who has responsibility for bringing together the modules for type examination and for production control, and ensuring that they are compatible, or he may be totally responsible for every aspect under the module “Internal Control of Production”.

By definition, certification is the action of a third party (see ISO/IEC Guide 2).  Clearly the issuing of the DoC is the action of the first party and therefore falls outside the definition of certification.  However, one or more of the process leading to the issuing of the DoC may involve a third party (the Notified Body) and each part of the process may be referred to, colloquially, as “certification”.

 

IECex: Certificate

As opposed to ATEX, IECEx has been made from the outset as a Type 5 Certification Scheme, relying on a single third party to bring together all aspects of design and production control before issuing a publicly available certificate.  Thus the public domain documentation is a certificate issued by the certification body.  Furthermore, because of the online IECEx database, any purchaser of the equipment can check the current status of the certificate on the web.

 

Differences

ATEX has one advantage over IECEx, being that it is possible to fudge compliance with standards.  Although an advantage when correctly applied to assist in the introduction of new technology, it does leave doubt as to exactly which requirements from standards have been applied in order to claim compliance with the EHSRs.

 

Opposed to this, IECEx is totally transparent and you get what you see: absolute compliance with the nominated standards.

 

Notified Bodies for the ATEX Directive are appearing everywhere in Europe, it is a commercial free-for-all and it is not entirely clear where some of these bodies are getting their expertise, or the criteria being used for notification.  It is a complicated subject and debated among the professionals.

 

IECEx has a better controlled process to monitor the level of competence of the certification bodies that it admits to membership, therefore giving confidence in the quality of the work of the body and the degree of confidence that can be put in the certified equipment.

 

Will IECex conquer the world?

The target end point should be acceptance of an IECEx Certificate directly into Europe as meeting the ATEX Directive.  There is still a way to go before this is a reality. In the mean time, by conforming to the IECEx procedures it is possible to produce a set of documentation that merely requires an ATEX front page to meet the requirements of both schemes. This means that a certification process covering IECex will also cover ATEX.

 

So, which scheme should I go for?

Currently, both ATEX and IECex are recommended. 5 years from now, IECex is likely to dominate the jungle of certification schemes, enabling one scheme for all countries.

 

 

Hazardous location categories: zones vs. divisions / World vs. North America

Wiring practices in hazardous locations are still subject to debate—whether the U.S. should change its method of classifying locations by divisions and adopt the European method of zone classification. It is also affecting businesses throughout the industry. Some fear the zone method would replace existing jobs because of the lack of conduit installations in zone-classified equipment. Others say it's economically smart to switch; the installation materials are less expensive. Here isan easy way to see the differences between the zones and divisions, as described by UL's Hazardous Locations Services.

 

Class I

Flammable gases, vapors, or liquids

Class I area classification North America (NEC 500) ATEX/IECex (NEC 505) Division 1: Where ignitable concentrations of flammable gases, vapors, or liquids can exist all the time or some of the time under normal operating conditions. Zone 0: Where ignitable concentrations of flammable gases, vapors, or liquids are present continuously or for long periods of time under normal operating conditions.   Zone 1: Where ignitable concentrations of flammable gases, vapors, or liquids are likely to exist under normal operating conditions. Division 2: Where ignitable concentrations of flammable gases, vapors, or liquids are not likely to exist under normal operating conditions. Zone 2: Where ignitable concentrations of flammable gases, vapors, or liquids are not likely to exist under normal operating conditions.

Class I groups Division 1 and 2 A (acetylene) B (hydrogen) C (ethylene) D (propane) Zone 0, 1, and 2 IIC (acetylene and hydrogen) IIB (ethylene) IIA (propane)

Class I temperature codes Division 1 and 2 Zone 0, 1, and 2 T1 (≤ 450°C) T1 (≤ 450°C) T2 (≤ 300°C) T2A, T2B, T2C, T2D (≤ 280°C, ≤260°C, ≤ 230°C, ≤ 215°C) T2 (≤ 300°C) T3 (≤ 200°C) T3A, T3B, T3C (≤ 180°C,≤165°C, ≤ 160°C) T3 (≤ 200°C) T4 (≤ 135°C) T4A (≤ 120°C) T4 (≤ 135°C) T5 (≤ 100°C) T5 (≤ 100°C) T6 (≤ 85°C) T6 (≤ 85°C)

 

Class II

Combustible dusts

Class II area classification Division 1: Where ignitable concentrations of combustible dusts can exist all the time or some of the time under normal operating conditions.   Division 2: Where ignitable concentrations of combustible dusts are not likely to exist under normal operating conditions.

Class II groups Division 1 and 2 E (metals—division 1 only) F (coal) G (grain)

Class II temperature codes Division 1 and 2 T1 (≤ 450°C) T2 (≤ 300°C) T2A, T2B, T2C, T2D (≤ 280°C, ≤ 260°C, ≤ 230°C, ≤ 215°C) T3 (≤ 200°C) T3A, T3B, T3C (≤ 180°C, ≤ 165°C, ≤ 160°C) T4 (≤ 135°C) T4A (≤ 120°C) T5 (≤ 100°C) T6 (≤ 85°C)

Class III

Ignitable fibers and flyings

Class III area classification Division 1: Where easily ignitable fibers or materials producing combustible flyings are handled, manufactured, or used. Division 2: Where easily ignitable fibers are stored or handled.
Class III groups Division 1 and 2 None.	Class III temperature codes Division 1 and 2 None.
Note: Article 503 of the National Electric Code limits the maximum temperature for Class III equipment to 165°C for equipment not subject to overloading and to 120°C for equipment that may be overloaded.

 

Source: UL's Hazardous Locations Services

 

 

Protection methods

 

The IECex standard (60079) presents a range of different protection methods.

 

Intrinsic Safety a	ia	60079-11
Intrinsic Safety b	ib	60079-11
Flameproof	d	60079-1
Pressurization	p	60079-2
Increased Safety	e	60079-7
Encapsulation	m	60079-18
Oil Immersion	o	60079-6
Powder Filling	q	60079-5
Non-sparking	n	60079-15
General Requirement		60079-0
Inspection & Maintenance		60079-17

 

 

 

 

Gas Groups

 

Methane	I
Propane	IIA
Ethylene	IIB
Hydrogen	IIC
Acetylene	IIC
All Gases	II

 

 


Certification marking

* For IECex, the "EEx" symbol is replaced with "Ex"

 

 

Certification modules:



 

Group	Cat	Athmosphere	Protection	Required protection
I (Mines)	M1	Methane & Dust	Very High	Two faults, remain energized and functioning
I (Mines)	M2	Methane & Dust	High	Severe normal operation, De-energize in exp. atm.
II (Above Ground)	1	Gas,Vapor, Mist, Dust	Very High	Two faults
II (Above Ground)	2	Gas,Vapor, Mist, Dust	High	One fault
II (Above Ground)	3	Gas,Vapor, Mist, Dust	Low	Normal operation

 

 

Ingress protection and rugged rating

Below is the official Ingress protection and Impact rating scheme. IP numbers are often rated on enclosures and connectors etc. to indicate protection from solids, liquids and impact. The table below gives a description of these ratings. Note that the third number, protection against impacts, is often omitted.

 

Example of Ingress protection number is IP68. This translates to mean 15 Meters or 50 feet Indefinite submersion of the object into water.

 

	First Number - Protection against solids	Second Number - Protection against liquids	Third Number - Protection against mechanical impacts (often omitted)
0	No Protection	No Protection	No Protection
1	Protected against solid objects over 50mm	Protected against vertically falling drops of water	Protected against impact of 0.225 joules
2	Protected against solid objects over 12mm	Protected against direct sprays up to 15° from vertical	Protected against impact of 0.375 joules
3	Protected against solid objects over 2.5mm	Protected against direct sprays up to 60° from vertical	Protected against impact of 0.5 joules
4	Protected against solid objects over 1mm	Protected against direct sprays from all directions - limited ingress permitted	Protected against impact of 2.0 joules
5	Protected against dust - limited ingress permitted	Protected against low pressure jets from all directions - limited ingress permitted	Protected against impact of 6.0 joules
6	Totally protected against dust	Protected against strong jets from all directions - limited ingress permitted	Protected against impact of 20.0 joules
7		Protected against effects of immersion from 15cm - 1m
8		Protected against long periods of immersion under pressure