Electrical Equipment for Hazardous Areas - Classification, Design and Standards

Hazardous Areas Technical Guide - This excellent 90 page technical guide from Weidmuller is a large pdf download at 5 Megs, however it is worth the wait!

Intrinsic Safety, Barriers and Isolators - A full page of great links.

A Common Regulatory Framework for Equipment Used in Environments with an Explosive Atmosphere - This is a publication that helps address the hazards in environments with a high risk of explosion such as mines, refineries, chemical plants and mills. The booklet can be used by countries that lack regulation in this sector as a blueprint for their legislation, and also for aligning existing national regulations with internationally harmonized best practice.

Basics of Explosion Protection - from Stahl. 

Electrical Apparatus and Hazardous Areas - Covers Hazardous Areas, Groups, Zones, Temperature Classes, Types of Protection, Equipment Protection Levels, Standards and ATEX - from Hexagon Technology.

Hazardous Area Classification and Control of Ignition Sources - This Technical Measures Document refers to the classification of plant into hazardous areas, and the systematic identification and control of ignition sources - from the UKHSE.

Electrical Information - Including Cenelec and IEC hazardous Area Information, North American Hazardous locations, IP code information and Abbreviations, Acronyms and Definitions - From Hawke International.

Hazardous Areas Technical Guide - This publication provides a brief overview of the essential aspects of explosion protection. Ultimately, safety in a potentially explosive atmosphere is a team effort. Manufacturers have a responsibility to ensure only safe equipment is placed on the market. Installers must follow the instructions provided and use the equipment only for its intended purpose. Finally, the user has a duty to inspect and maintain the equipment in a safe working order - from Warom.

Hazardous Area Classifications and Protections - The intent of this document is to provide a broad overview of hazardous area classifications and the types of protection techniques involved - from Emerson Process Management.

Hazardous Area Installations - How to make 92% of sites safer without increasing the costs of compliance - From Abhisam Software.

How to Manage Hazardous Areas effectively by using Gas Monitors - Electrical equipment installed in hazardous areas, necessarily has to conform to the area classification for that area. However, frequently, practical problems arise, where the specified equipment may not be easily available. For example, an area classified as Zone 1 under the IEC system, theoretically can accept only Zone 1 equipment. However sometimes, especially in case of specialized equipment, Zone 1 certified equipment of that type may not be available. In such cases what could be done? This paper presents the background of such situations, possible solutions and current international practices regarding this issue - from Abhisam Software.

Minimum Ignition Energy (MIE) - In the following table MIE is quoted for flammable substances mixed with air. A reference is provided to indicate the source of the data. MIE values are provided for guidance only. Please check references for specific measurement conditions - from Explosion Solutions.

From TRANSTEK - Product Certification for Hazardous Areas - Just as it isn't easy to manufacture a device for use in a potentially hazardous environment, understanding the maze of different standards, zones, divisions, temperature classifications and markings is something of a nightmare for those trying to find the right equipment that meets the required standards for their application. What follows therefore is an attempt to answer some of the many questions regularly posed relating to:
- The major standard and assessment systems used in Australia & overseas (IECEx, ATEX, NEC, etc.)
- Hazardous Area Zones (Zone 0, 1 and 2)
- Temperature Classifications (T ratings)
- Safety protection concepts (Intrinsically Safe / Flameproof / Encapsulation, etc.)
- Device markings Just what do all those letters and numbers really mean?

The following papers and presentations are from the IDC Technologies "Hazardous Areas: Classifications and Equipment Conference 2007", these papers are recommended reading.

Electrical Equipment in Hazardous Areas - Field Inspections - Bill Rankin - This paper focuses on the problems which are directly related to the inspection process. It has been written from the perspective of the Ex inspection team who usually have no control over the design and installation process. It is acknowledged that the competency of the design and installation personnel will affect the quality of the installation that is to be inspected. The failure of Ex inspection campaigns can be attributed to four main areas:

- Poor planning of the Ex inspection activities
- Lack of competence of the Ex inspectors
- Lack of clarity of the inspectors’ roles
- Lack of clarity of the inspection scope

Ex Inspections—Potential Pitfalls - Alan Wallace- Inlec Engineering - Many, if not most, Ex inspection campaigns are grossly inefficient, and their
effectiveness is often questionable. This presentation discusses the four main reasons why Ex inspection campaigns fail to meet the client's expectations. It also offers recommendations to improve the quality and efficiency of Ex inspections.

The Application of Intrinsic Safety to Fieldbus Systems - Chris Towle Chairman: MTL Instruments Ltd - This excellent paper covers the technical aspects of FISCO, FNICO, Exe and Exi combination, Maintenance and Inspection along with Intrinsically Safe Ethernet.

Myths and Actual Practice with Industrial Data Communications and Hazardous Areas - Steve Mackay - IDC Technologies - This presentation covers Practical examination of data communications systems in hazardous areas for Ethernet, Foundation Fieldbus, Profibus or RS-485 along with Practical guidelines for best practice in designing your next industrial data communications system in a hazardous area.

The Current State of the IEC Intrinsically Safe Standards - Chris Towle - Chairman: MTL Instruments Ltd - A candid discussion on the IEC IS standards which includes IEC Organisation, Intrinsic Safety Standards, An Analysis of the Change from ‘nL’ to ‘ic’ and advice to the First-time Designer.

Changes to Certification and its Impact on Manufacturers - Des McDonell CSE-Ex Pty Ltd - This presentation covers product certification in Australia.

Gases and Vapours - Gases and Vapours (and Mists) mix more or less homogeneously with air and form flammable mixtures relatively quickly. While this is obvious for gases, vapours can travel very quickly and form flammable or explosive mixture with air in a very short time frame - from EPEE Consulting.

Flammable / Combustible Liquids - While the dangers of flammable liquids are well known, combustible liquids can be as dangerous under certain conditions. The vapour space in storage tanks is a Zone 0 are even for combustible liquids. Should the ambient temperature approach the flash point of combustible liquid within 6 deg C, it has to be treated as if it were a flammable liquid - from EPEE Consulting.

The following papers and presentations are from the IDC Technologies "Hazardous Areas: Classifications and Equipment Conference 2009", these papers are recommended reading.

It’s Not Rocket Science Unless You Do It Wrong - Dave Adams - Technical Advisor - Hazardous Locations Equipment: Canadian Standards Association International - The certification of hazardous locations electrical equipment is changing, and will continue to change, for some time. There has never been a more confusing time for manufacturers, end-users, and certification agencies alike. This paper does not really have a point, or maybe it has several. While it provides answers, it will also raise new questions. It is really just a strung-together collection of miscellaneous observations, ramblings, and rants, garnered from 18 years in the business of certifying hazardous locations equipment.

Proper Grounding of Instrument and Control Systems in Hazardous Locations - Joe Zullo - Regional Sales Manager: MTL Americas - Grounding is defined as electrical equipment connected directly to mother earth, or to some conducting body that serves in place of the earth, such as the steel frame of a plant and its earth mat or the hull of a ship or oil drilling platform. Proper grounding is an essential component for safely and reliably operating electrical systems. Improper grounding methodology has the potential to bring disastrous results from both an operational as well as a safety standpoint. There are many different categories and types of grounding principles. This paper’s primary focus is to demonstrate proper grounding techniques for low voltage Instrument and Control Systems (IACS) that have been proven safe and reliable when employed in process control facilities.

The New Dimension of Intrinsic Safety - Rick Ogrodzinski - Project Leader - Global Projects Team, Process Automation Division: Pepperl + Fuchs, Inc - intrinsic safety type of protection is currently achieved by limiting the available power. This limitation of power - usually to less than 2 W - provides intrinsic safety (Ex i) and is therefore mainly employed in the area of control and instrumentation in the power supply to actuators and sensors with low connected load. A significantly higher direct power with the simultaneous safeguarding of all the positive characteristics of intrinsic safety offers the user a new and essentially wider scope of application. These aims are achieved through DART technology (DART: Dynamic Arc Recognition and Termination). DART is a means of instantaneous tripping, which dynamically detects an undesired condition or a fault in the electrical system precisely as it occurs and instigates an immediate transition to a safe condition before any safety-critical parameters are exceeded. DART is based on the detection of fault conditions and their characteristic rate of rise of current.

The following papers and presentations are from the IDC Technologies "Hazardous Areas Conference 2015", these papers are recommended reading.

Hazardous Area Classification of Large Scale Plants - Paul Spresser - The hazardous area classification of a large scale plants can be problematical. A preference to use the generalised method of classification exists and its use is easily substantiated, for most aspects of these plants. However, unless some clear cut guidelines are established and allowance is made for a certain level of exceptions to the main adopted methodology, impractical solutions can result. Room must be left for use of the Source of Release by example and calculation methods for a practical classification solution - from EPEE consulting and IDC Technologies.

Explosive Hazardous Areas - In the Mining Environment - Aaron Drew - This paper discusses the effects on mine design, operation and maintenance as a result of the inclusion/use of chemicals that produce explosive atmospheres. A brief discussion in relation to the acceptance of EEHA principles within the mining community - the age old how can it be hazardous when you can eat it argument. Finally, mines are interesting in as much as they may have both dust and gaseous hazardous areas, what is the outcome when the hazardous zones overlap and a piece of equipment must be certified to both dust and gaseous requirements? Is such equipment readily available in the market? - from Primero Group and IDC Technologies.

Risk Based Prioritisation of Ex Equipment Non-Compliances - Alan Wallace - In most facilities, electrical equipment in hazardous areas must be installed in accordance with AS/NZS60079.14. Due to decay, damage, incorrect original installation, or maintenance, electrical installations in hazardous area may not be fully compliant with the installation standard. Many OpCos spend hundreds of thousands of dollars conducting periodic Ex inspection campaigns, in accordance with AS/NZS60079.17. It is usually not possible to rectify all of these Ex non-compliances immediately. This is especially true when there are many Ex non-compliances. The non-compliances are usually prioritised for rectification. However, in most cases there is no structured and justifiable basis for the prioritisation applied. This paper discusses a qualitative risk based approach to prioritisation to ensure that the Ex non-compliances creating the highest risk are addressed first. The methodology achieves a balance between being simple to apply vs. considering all of the factors that contribute to the risk - from Inlec Engineering Australasia.

Training Competencies for Electrical Equipment in Hazardous Areas - Paul Egan - Within industry, there is much confusion, as whether it is a requirement to have nationally accredited competencies for any electrical work carried out with Electrical Equipment in Hazardous Areas (EEHA). The legislation in Western Australia calls up the Australian / New Zealand Standard 60079 series. AS/NZS Standard 60079-14 requires, anyone carrying out work in the areas of design, classification, installation, inspections and maintenance, be competent to the requirements of AS/NZS 4761:2008 Even though these standards clearly require certain competences to be able to carry out works in hazardous areas, there are many organisations that do not understand or don’t care to have their personnel correctly trained to these standards. It is also a requirement to have awareness training for anyone (non electrical) who is working in the hazardous area. There is also the issue of just obtaining the minimum required competencies, as this is often not enough. Further mentoring and milestone achievements are often required before a person can truly be deemed competent to carry out work in these areas. This presentation highlights the requirements for all training required and what training needs to be undertaken, to demonstrate competency in EEHA design, classification, installation, inspection and maintenance.

Death by Standards - S. Srinivas Shastri - Technology has advanced significantly over the past several decades, and this has resulted in not only better materials of construction but also in tailor made instrumentation and tight process control. As accidents have occurred in the past (Piper Alpha, Bhopal, Flixborough, and other unfortunate events) there is a greater understanding of process systems and materials. All these advances have led to documenting best industry practice in the form of standards, codes and practices. Legislation has been implemented that often draws upon these standards, however, there application of the standards is not prescriptive. The interpretation and the application of standards is the role of the practicing engineer and she/he should draw upon wisdom in ensuring compliance and most critically safety of the operation. This paper has very few references as it is an ‘applied paper’, however it does draw heavily from the usual normative hazardous area classification standards relevant to Australia - AS/NZS 60079.10.1 and API RP 505 specifically. In the context of this paper these standards are those editions that were current as of 2014. This paper discusses two classification examples from a recent large LNG project.

Area Classification and Major Hazards - Lars Rogstadkjernet - Hazardous area classification and major hazards risk assessments have a common objective: to assure a plants operability and safety by preventing ignition. Yet, the two tasks are often carried out without much consideration of the other. Hazardous area classification is prescriptive and oriented toward high frequency events whereas risk analysis is usually performance oriented and focus on rare events. Legislative requirements for major hazards typically refer to rare events: those occurring every 10 000 or 100 000 years, with the requirement being that unacceptable events cannot occur more frequent than this. Consequently, the scenarios being of concern to the risk assessor can be much different to those normally thought of for zoning purposes even if they are somehow dealing with the same problem: preventing ignition. Ignition is a major factor in a risk analysis and a potent ignition source outside a classified area may be of crucial importance. Similarly there may be areas where classification is mandated but of lesser importance in the eyes of a risk assessor. A key point for this paper is ignition hazard beyond the boundaries of area classification. Case examples will be used to illustrate how ignition from non EX areas impact on risk as well as well as examples of where EX proofing is less critical - at least in the eyes of a risk assessor.

A Case Study: Hazardous Area Considerations for Diesel Storage in a Hot Climate - Daniel Bianchini, Justin Van Staden and Harrison Cox - Hazardous areas are most often associated with the storage and handling of flammable liquids. However, in certain circumstances hazardous areas can occur around combustible fuel installations. This paper explores a specific case study involving the above ground storage of diesel in a hot climate (Pilbara, WA) and investigates scenarios to inform the understanding as to when hazardous areas might occur. Issues reviewed include the relationship between ambient conditions and the temperature of the fuel being handled, spill scenarios, and the potential formation of sprays and mists.

Hazardous Area Classification: The Dangers of Using Standards for Determination of Hazard Zones - Kehinde Shaba, Colin Hickey - There are many benefits to using standards to determine the hazard radius in hazardous area classification applications. By codifying existing knowledge they ensure rapid and timely delivery of required results. However, they suffer from a number of limitations - chief of which is a lack of specificity. This paper discusses the pitfalls/challenges of using standards for establishing hazard radii and then discusses how they can be addressed by the use of detailed consequence modelling. A case study comparison of the two approaches is also outlined as well as the benefits of using a more targeted approach.

Machine Safety in Hazardous Areas - Ross De Rango - The principal interest of this paper is zoning. Other considerations of course need to be taken into account to ensure that equipment installed is safe for the location, but it is zoning that has the most impact in the context of design choices for machine safety systems in hazardous areas.

Fire and Explosion Protection of Electrical Installations with New Advanced Suppression Systems - Andrew Kim - Senior Research Officer - Fire Research Program, Institute for Research in Construction - National Research Council of Canada The National Research Council of Canada (NRC) has carried out projects to evaluate the fire and explosion protection effectiveness of new technologies technologies which will be examined and discussed. There is a potential for a very large fire or explosion when using electrical equipment in areas where flammable gases could accumulate or in room containing power transformers. Recently, several new fire suppression technologies have been developed to provide protection in an environment with an explosive atmosphere or to provide suppression of a large fire involving electrical equipment, such as power transformers. In one project, the explosion suppression effectiveness of hybrid gas generators in providing safety to occupants in a compartment against a deflagration type explosion was evaluated. Hybrid gas generator systems combine gas generator technology with a liquid fire suppression agent. In another project, the effectiveness of a newly developed compressed-air-foam (CAF) system was evaluated to provide fire protection in power transformers. Thanks to the National Research Council Canada.

Comprehensive Global guide to Hazardous Locations And boy is this comprehensive! It is an excellent technical resource from Cooper Crouse Hinds which includes virtually everything including: Basics of Explosion Protection, Area Classification, Methods of Explosion Protection, Equipment Selection, Installation & Wiring Practice.

Ex poster (inc ATEX) - thanks to Endress + Hauser.

Flammable Risk - from Crowcon.

Hazardous Area Classification/ Flameproofing - From the UK Health and Safety Executive.

Hazardous Area Reference Chart - From Crouse-Hinds.

Extronics Wall Chart - Some Useful Ex Information here.

MTL Luton UK Technical Information - You will have to register to get access- it is quick, easy and worth it!

Flammable Facts Poster - This poster from MTL gives a quick look at the most important facts associated with Electrical Equipment in Hazardous Areas.

A Guide to Risk Based Assessments of In-situ Large Ex 'e' and Ex 'N' Machines - Whilst not free this guide provides a practical method to undertake a comparative evaluation of the risk of incendive discharges occurring in existing large Ex 'e' and Ex 'N' high voltage machines in potentially explosive atmospheres.

How Can You Manufacture Explosion-Proof Equipment and Systems to World-Class Safety Requirements? - Depending upon the Zone of usage, electrical, electronic and mechancial equipment intended for use in potentially hazardous environments must be independently evaluated for their impact on overall safety. The European Union’s ATEX Directive and the IECEx Certified Product Scheme are two assessment routes used for the safety of equipment used in such environments. This white paper provides an overview of these two routes and provides answers to frequently asked questions. You will have to register to download this paper from TÜV SÜD. 

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