lighting for potentially explosive...

Lighting for Potentially Explosive Environments

Version 3.0, April 2015

Intertek

Deeside Lane, Chester, CH1 6DD UK

[email protected] 01244 882590 www.intertek.com/hazloc

mailto:[email protected]

http://www.intertek.com/hazloc

Lighting For Potentially Explosive Environments

Contents

Contents ............................................................................................................. 1 Introduction ......................................................................................................... 1 Where do you find potentially explosive environments? ........................................ 2 Geography .......................................................................................................... 2 Fundamental Information – ‘Protection Concepts’ ................................................ 3 Protection Concepts ............................................................................................ 3 EU Compliance - ATEX Directive 94/9/EC ............................................................. 5

ATEX 94/9/EC Certification requirements ...................................................... 6 Markings ...................................................................................................... 6

IECEx ................................................................................................................... 6 North America ..................................................................................................... 7

Option 1: Full Listing (certification) with ‘Authorisation to Mark’ ................... 7 Option 2: Limited Production Certification (LPC) ............................................ 7 Option 3: Unit verification ............................................................................. 8

What you’ll need to get a quotation for compliance services ................................ 8 Advances in Lighting Technologies ....................................................................... 8 Common misconceptions and issues .................................................................... 9

Performance versus compliance .................................................................. 10 In summary ........................................................................................................ 10 How Intertek can help ....................................................................................... 11 Contacts ............................................................................................................ 11

Introduction

A potentially explosive environment is one where, the presence of dust, gas or vapours means the atmosphere could potentially combust should an ignition source be introduced.

As lighting tends to be electrically powered, the possibility of a stray spark from a lighting system, could lead to major explosion. Luminaire manufacturers therefore use a number of techniques to make their products as safe as possible to enable them to operate in these challenging environments.

This paper provides a summary of the protection concepts used by product designers to make hazardous area safe products and gives a basic overview of the requirements for lighting products intended for potentially explosive environments. It will also indicate routes to product compliance that manufacturers might consider.

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Where do you find potentially explosive environments?

• Automotive refuelling stations or petrol stations • Oil refineries, rigs and processing plants • Power generation • Chemical processing plants • Printing industries, paper and textiles • Pharmaceutical production/manufacture • Aircraft refuelling and hangars • Surface coating industries • Underground coalmines • Sewerage treatment plants • Gas pipelines and distribution centres • Grain handling and storage • Woodworking areas • Food processing plants • Sugar refineries • Metal surface grinding, especially from metal dusts and particles • And others

All of these environments need to be lit safely – so creating lighting suitable for these environments presents an enormous potential market.

Geography

Before any product designer puts pencil to paper, they need to consider where they intend the finished product to be installed. Most territories have their own Standards and regulations that govern the installation, use and maintenance of equipment in potentially explosive environments.

Designing products to the Standard(s) that govern the product in your target market (whilst this seems counter to innovation) greatly increases the likelihood of meeting those requirements on first assessment. Modifying an existing product to cope with potentially explosive environments is obviously more challenging, but suitable modifications can be achieved with the right support.

In the EU, designers are faced with meeting the requirements of a number of regulations, such as the ATEX Directive. The current version of the Directive, 94/9/EC is being replaced with 2014/34/EU which comes into force on 20th April 2016. In the US, the National Electrical Code governs requirements. Other territories have their own rules, but broadly speaking designers are looking to achieve compliance for multiple territories.




Such as:

• The National Electrical Code, FM, UL and CSA Standards for the USA & Canada

• EN Standards and Applicable Directives (such as ATEX) for the EU • IEC Standards and local regulations for all other international territories

Fundamental Information – ‘Protection Concepts’

The most fundamental information needed by product designers developing lighting for potentially explosive environments, is a reference list of ‘protection concepts’ – these are design principles that ensure that their products do not provide ignition sources, such as flames, sparks, friction and heat.

Generally a potentially explosive environment is divided into Zones in the EU and Divisions in the US – these determine the level of risk present in particular areas.

Particular protection concepts are applied to equipment for use in classified areas.

You can work with your test and certification partner to develop an understanding of protection concepts and how they affect your designs.

Protection Concepts

The following tables show the protection concepts for the EU/IECEx and North American approaches.

Note on the North American table, both divisions and zones are referred to in the ‘Area classification’ column - showing both the NEC 500 and NEC 505 approach.




Figure 1: North American protection concepts

The EU/IECEx table shows a lengthier list of protection concepts than the North American table. The application of protection concepts to a design will be used by an evaluating body in the respective regions to determine lighting compliance with local requirements.




Figure 2: EU and IECEx protection concepts

EU Compliance - ATEX Directive 94/9/EC

The European ATEX Directive applies to equipment and protective systems intended for use in potentially explosive atmospheres. It is mandatory for organisations in the EU to follow the Directive to protect employees from explosion risk in areas with an explosive atmosphere. The regulations apply to all equipment intended for use in explosive atmospheres, whether electrical or mechanical and include protective systems.

The Directive 94/9/EC divides equipment into categories, which determines in what zones equipment can be used.




ATEX Category

Zone Definition of zone

Gas Dust

1 0 20 Hazardous atmospheres are present under normal operation and for long periods of time.

2 1 21 Hazardous atmospheres may be present under normal operation but only for short periods of time.

3 2 22 Hazardous atmospheres only present under fault conditions and only for very short periods of time.

M1 I (Mines with firedamp)

M2 I (Mines with firedamp)

ATEX 94/9/EC Certification requirements Product Certification - Electrical - Categories 1 & 2 (M1 & M2) and Safety Devices

• Test & certification of equipment by Notified Body • Certification of Quality System by Notified Body

Product Certification - Electrical - Category 3 – Self Declaration by manufacturer, assessment to relevant Standards

• Internal Control of Production

Product Certification- Non-Electrical - Category 1 & M1 and Safety Devices (e.g. vent panels)

• Test & certification of equipment by Notified Body • Certification of Quality System by Notified Body

Category 2 & M2 - Requires a Technical Dossier to be lodged with a Notified Body

Category 3 - Self Declaration by manufacturer

• Internal Control of Production

Markings Manufacturers who apply its provisions and affix the CE marking and the Ex marking are able to sell their equipment anywhere within the EU without any further requirements being applied with respect to the risks covered.

IECEx

The IECEx Scheme was established in 2003 as a means of mutual recognition by various national laboratories, of equipment and services intended for use in explosive atmosphere environments, while maintaining the required level of safety.




The IECEx is a voluntary program, and it’s primary objectives include cutting certification costs, speeding turnarounds, reducing time to market, providing one international database listing, and building and maintaining international confidence in the product assessment process.

IECEx requires that electrical equipment demonstrates conformity to IEC 60079 series Standards to secure an Ex Test Report (Ex TR). This can then be used to approach IEC Ex scheme bodies in target countries for recognition of compliance. Currently the following countries recognise IEC Ex Standards:

Australia (AU), Brazil (BR), Canada (CA), China (CN), Croatia (HR), Czech Republic (CZ), Denmark (DK), Finland (FI), France (FR), Germany (DE), Hungary (HU), India (IN), Italy (IT), Japan (JP), Korea (KR), Malaysia (MY), Netherlands (NL), New Zealand (NZ), Norway (NO), Poland (PL), Romania (RO), Russia (RU), Singapore (SG), Slovenia (SI), South Africa (ZA), Spain (ES), Sweden (SE), Turkey (TR), United Kingdom (GB), United States of America (US)

North America

The legal requirement to test and certify products for sale in the United States is designated by the Occupational Safety and Health Administration (OSHA) and it requires products to be assessed by a Nationally Recognized Testing Laboratory (NRTL).

Intertek is an OSHA recognised NRTL and is accredited as a Testing Organization and Certification Body by the Standards Council of Canada.

There are several routes to product compliance - tailored to a manufacturer’s production capacities.

Option 1: Full Listing (certification) with ‘Authorisation to Mark’ This is ideal if for those producing a large quantity of products or components on an on-going basis and entails:

• Initial factory inspection • Full product testing to the appropriate product Standards • Quarterly site inspections • On-going surveillance by the NRTL

Option 2: Limited Production Certification (LPC) This option intends to support the compliance of an anticipated ‘batch’ of products produced within a defined three-month period. This entails

Figure 3: An example of our NRTL Mark for North America




• Full product testing to the appropriate product Standards

Should you need to produce more units, the three-month period can be renewed.

Option 3: Unit verification This option supports the creation of bespoke products and entails

• Full product testing to the appropriate product Standards (as far as possible without damaging the unit)

Acceptance by Authorities Having Jurisdiction (AHJs) NRTL marks are recognised by local inspectors and Authorities Having Jurisdiction (AHJs) throughout North America and also in some areas of South America.

Intertek is an NRTL recognized by OSHA, and our ETL Listed Mark is an accepted by AHJs as proof of product compliance.

What you’ll need to get a quotation for compliance services

The process for full authorisation to mark begins with getting a quote. To get an accurate quotation, a manufacturer should provide:

• Drawings/Product Photographs (if available) • Product Specifications (dimensions, power ratings, materials list etc) • Product description (intended use) • Details of any approved/certified components in the finish product • A prototype or regular sample (if available) • Existing test reports and certification for IECEx if applicable • Ordinary location compliance paperwork

Advances in Lighting Technologies

Whilst lighting products had made technological advances during the previous decades, it may be seen that in recent years, the advent of solid state LED lighting has been a noticeable step change in lighting technology. It is this technological change that has brought many new and varied lighting applications from safe to hazardous areas.

With lighting manufacturers seeing opportunities for their normal area LED products in the lucrative hazardous area equipment market, many may fall into the




trap of aiming for the best possible certification without actually considering the likely zones of use, and the subsequent easing of test requirements for these less onerous areas.

There is no ‘catch all’ Standard which links both the testing of normal and hazardous area lighting so there is still the requirement to test separately to the Standards listed above as well as to the traditional lighting Standards such as IEC/EN 60598 & IEC/EN 61347 and their variants, and if necessary, LED specific ones, IEC/EN 62031 & IEC/EN 62471

Common misconceptions and issues

When looking at the family of explosive atmosphere Standards for the first time, some engineers may think that the likes of LED lighting could automatically be suitable for Intrinsic Safety, given the relatively low powers and potentially low voltage applications. This however needs to be tempered by the fact that an Intrinsic Safety investigation would require the engineer to assess what the theoretical worst case scenarios could be, when taking into consideration multiple faults, such as breakage of tracks and wires, failure of components, and addition of capacitors.

For example, if an LED luminaire is fed from a nominal 28V supply, then by its nature the circuit would likely not be thought to spark, however the breakage of conductors, and in some cases, the re-making of these conductors must be considered. If the luminaire nominally draws 0.5A, then in theory, as per the parameter tables of IEC60079-11, the combination of voltage and current is non-incendive, i.e. a spark from this source could not ignite many of the commonly known gases or vapours. However, we cannot rely on nominal values and must consider what happens when the supply fluctuates. When components are not suitably rated, fault scenarios may lead to voltages and current far in excess of those considered “nominal” or non-incendive.

Next, if a luminaire is found to reach maximum surface temperatures of the order of 150°C under R&D and production testing, this may be found to be noticeably higher under Intrinsically Safe conditions, i.e. when testing under R&D conditions, the need to fault all of the available power into a single component may not have been considered, but with Intrinsic Safety this is invariably always either assessed using known data, or tested to prove mounting conditions, etc, have minimal effect. This test/assessment method may bring about surface temperatures well over 200°C.

Also, when specifying parameters such as T-Class and apparatus group, it is worth referring to IEC60079-20-1 (“Material characteristics for gas and vapour classification – Test methods and data”) where the Standard shows only two T6




rated gas (i.e. a gas with an auto-ignition temperature in the range of 85°C to 100°C), Carbon Disulfide CS2, Nitrous acid ethyl ester(= Ethyl nitrite*) CH3CH2ONO, and only four IIC (MESG < 0,55 mm, or MIC < 0,5) rated gases, Hydrogen H2, Ethine(=Acetylene)(= Ethyne) CH≡CH , Carbon Disulfide CS2, Dichlorodiethylsilane (= Diethyl-dichloro-silane)(C2H5)2SiCl2, Coke oven gas, Water gas (Mixture of CO + H2), and as such, to drop the specified parameters to IIB & T5 (or even T4) would have little practical detriment in the vast majority of applications for hazardous area lighting, but bring positive effects to the test/assessment/certification success and time scales.

Note that some lighting products will lend themselves to other concepts e.g. Ex d

Performance versus compliance It may be stating the obvious, but manufacturers of lighting products will invariably try to get maximum light output from their product for the given design parameters. In doing this, a by-product is most often high localised temperatures. This is more obvious with LED lighting due to the very small size of the LED. Effective heat-sinking will help to reduce this localised heating, but the heat sink methods need to be shown to be robust enough to withstand any physical or thermal/humidity testing that may be conducted, i.e. reliance on viscous heat-sink pastes to hold PCBs to heat sinks will invariably cause the PCB and heat-sink to have poor heat transfer properties, and as such, the test engineer should consider such foreseeable conditions and test accordingly.

*The auto-ignition temperature of ethyl nitrite is 95 °C, above which the gas suffers explosive decomposition. In summary

Forging a strategic partnership with your test and certification partner can help to ensure that you’re aware of the requirements that your lighting product faces in its target markets early in the design phase - to help you maximise your compliance through good design.

A strategic approach to testing and certification, planned as an intrinsic part of product development activities can also impact on how quickly your product is available for sale and how much it costs to develop and potentially revise.

Independent testing of your product has clear benefits in terms of freeing up time, money and personnel that you would previously have to invest in in-house testing.




This will help your acceptance in new markets, where perhaps your brand is not yet established.

Getting to grips with the difference between test certificates and product approvals will help you to choose the best compliance route for you and enable you to invest your compliance budget in the solution that delivers the best return on your investment.

Awareness of why products fail testing enables product designers to ‘design for compliance’, which will reduce the chances of product failure and reduce the overall time it takes to complete the compliance process too, saving you time and money as well as helping to get products to market faster.

How Intertek can help

• Intertek provides testing and evaluation solutions for Lighting products and products for potentially explosive environments.

• We offer compliance advice and product assessment services to meet international requirements.

• With our experienced Ex engineers supporting your project, you not only get the guidance you need, but also a fast service that helps speed your time to market – helping you realise return on your R & D investment much faster.

• By offering technical Ex services both on and offsite, our experts can tailor the assessment programme to suit your needs.

Contacts

Lighting Potentially explosive areas

Kevin Sweeney Harry Hamilton [email protected] [email protected]

Intertek Intertek Cleeve Road Deeside Lane Leatherhead Chester Surrey Flintshire KT22 7SB CH1 6DD Tel: +44 1372 370900 Tel: +44 1244 882590






For more information on specific testing and certification information, please contact Intertek at +44 1244 882590, email [email protected], or visit our website at www.intertek-hazloc.com.

This publication is copyright Intertek and may not be reproduced or transmitted in any form in whole or in part without the prior written permission of Intertek. While due care has been taken during the preparation of this document, Intertek cannot be held responsible for the accuracy of the information herein or for any consequence arising from it. Clients are encouraged to seek Intertek’s current advice on their specific needs before acting upon any of the content.




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