Hazardous Areas
Current trends in
industry
Carolyn Yates
Technical Director, Energy and Resources
Aurecon – Northern Territory
Hazardous Areas – Current trends in industry
Overview
 A few hazardous area basics
 Classification
 Explosion protection techniques and equipment
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Current trends in area classification
Design and installation
Inspection and maintenance
Common myths
Some of the interesting stuff 
Introduction
The disclaimer…..
Before we start, this presentation is based on Australian
requirements and jurisdictions. When working on projects in
other areas of the world, it is important to find out what the
requirements are in the location and follow them.
This presentation is designed to give a basic introduction to
hazardous areas and to provide some of my own experiences
as hazardous area designer, inspector and auditor. It is not a
competency course.
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What is a hazardous area?
Definition: Hazardous area
Hazardous area definitions are found
in several Australian Standards.
This definition for a hazardous area
comes from AS/NZS 3000 Clause
1.4.11.
“Area in which an explosive
atmosphere is present, or may be
expected to be present, in quantities
such as to require special
precautions for the construction,
installation and use of equipment
[AS/NZS 60079.0].”
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What is a hazardous area?
What does it really mean?
 An area that contains, or is reasonably expected to contain
flammable gases or vapours or combustible dusts, fibres or
flyings.
Generally if you have flammable gases or liquids, or
combustible dusts, you will most likely have a hazardous area.
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Around Darwin……..
 Darwin LNG (and Inpex Ichthys will also have some areas)
 Power stations (Channel Island, Weddell)
 Industrial facilities, such as the Vopak Fuel Terminal
 Some maybe less obvious examples:
 Service stations (bowsers and tanks)
 LPG refilling areas (eg BCF, BBQs Galore)
 Laboratories
 Airports (including aircraft hangars)
 Workshops (welding bays where acetylene is used)
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Did you know?
Flour (grain),
white/granulated sugar
and cocoa are highly
explosive and come
under the heading of
“combustible dusts”
Some of the worst
industrial explosions
have been due to
combustible dusts.
Other examples include
coal, citric acid
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Something to note……
It is rarely possible by simple examination of a plant or plant
design, without extensive experience, to decide which parts of
the plant are hazardous areas.
More detailed information is necessary and this involves the
analysis of the basic properties of the materials present and the
possibility of a release occurring.
Hazardous area classification is a specialist area.
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Which of these plants contain a hazardous area?
Plant A
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Plant B
Classification
Hazardous area classification divides areas in to Zones based on
the likely frequency and duration of a release, release rate,
concentration, velocity and ventilation of the area.
Hazardous area classification zones include
……but this is not the whole picture.
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Classification – Example of Zones for Gases &
Vapours
AS/NZS 60079.10.1 Figure ZA.4
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Classification - Jargon Alert!
Classification also considers the materials being considered
and assigns an equipment group and temperature classification
to the area based on the material properties.
Temperature class – T1, T2, T3…..T6 (400°C down to 85°C)
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How hot the thing gets…..
Also known as the autoigntion temperature
Equipment/Apparatus or Gas group - IIA, IIB, IIC
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How much energy it has – the spark energy…..
IIA is the least onerous, IIC the most
And this is the area that gets forgotten about……
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Common myths - Round 1
“We will just go with the worst case scenario and say that all
equipment installed needs to be IIC T6”.
Your installation will be very dark as you won’t be able to buy a light fitting.
But what about hydrogen?
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IIC gas – explosive…..BUT
Has an incredibly high autoigntion temperature - 560°C, which makes it a
T1 requirement
Acetylene is a nastier gas
Takeaway point - You need to check. It’s not always obvious.
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Current trends in classification
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The classic approach still in use is via examples in AS/NZS
60079.10.1
Equipment Protection Levels (EPLs) introduced in the last
update to the standard
Photo – Vopak Darwin (vopak.com)
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Current trends in classification
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What about other areas? (That are not covered in AS/NZS
60079.10.1…):
 Fuel wharves and berths (ship loading and unloading)
 Diesel areas
Other areas
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International standards to the
rescue!
IP15
 Good for fuel wharves and berths
(ship loading and unloading)
 API RP 505
 Diesel areas
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Dispersion Modelling for those
other hard to determine areas
 Gas pipeline pressure relief/venting
Diesel areas
 About diesel….
 Flashpoint is generally 61°C,
which makes it a combustible
 Australian standards only
require you to consider
hazardous areas for
combustible liquids which are
being handled above
(flashpoint – 6
degrees)…….this is 55°C for
diesel……
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Diesel areas
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Manufacturer caution
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Ullage spaces within tanks
Hazards from misting
So why talk about it?
 Some companies are taking a
very conservative line and are
treating all diesel as a
flammable, in case the 55
degree mark is breached
 But, many diesel
installations are classified
as non-hazardous…….
 Which way do you go?
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Design and installation
Back in the bad old days…..
Now…..
The design and installation of a hazardous area installation
must be completed by competent persons – to AS/NZS 4761.
It involves correct selection of explosion protection techniques
and installation requirements for the classified areas.
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Design and installation
There are many things to consider:
 Explosion protection techniques
 Ambient conditions
 Cable selection
 Location of equipment
 Additional electrical
requirements for different
protection techniques
 Certificates of conformity for
equipment
 Information for inclusion within
the verification dossier
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Common myths – Round 2
“Intrinsically safe areas”
– No such thing
“All hazardous area equipment is intrinsically safe”
– No it’s not. Other protection techniques are often in use
“Only industrial plants have hazardous areas”
– No again! Also found in education facilities, commercial buildings,
etc
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Equipment - Explosion protection techniques
There are many different explosion protection techniques. The
most common ones are:
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Flameproof enclosures “d”
Increased safety “e”
Intrinsic safety “i”
Non-sparking “n”
Encapsulation “m”
Special protection “s”
Protection by Enclosure “tD” (used to be DIP)
Refer to Sylvania Lighting Information Sheet
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Design and installation
Flameproof (Ex d) motor:
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Design and installation
Non-sparking (Ex nA) light fitting:
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Design and installation
Intrinsically safe
(Ex i) level transmitter
……..the one time it’s ok to call
something intrinsically safe…..when
it actually is.
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Inspection and maintenance
People performing inspections or maintenance shall be
competent.
 Inspections conducted to AS/NZS 60079.17
 Initial, detailed grade inspections on completion of
installation
 Maximum timeframe of 4 years between inspections
 Periodic inspections can be close or visual, however if major
defects are found, should be upgraded to detailed
inspections
 Defects must be rectified as soon as practicable
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Inspection and maintenance
In Queensland and Victoria, it is mandatory for a third party to
complete an inspection of the installation to confirm
compliance with standards and that the installation is safe.
The inspector will provide a permission to energise when they
are happy that the installation is safe and compliant.
This is not a legislative requirement in the NT, however many
industrial sites will insist on a third party verification of new
installations prior to energisation.
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Some of the interesting stuff
Why you should use proper flameproof “barrier” type glands
..\..\Videos\APLNG Cable.mp4
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Some of the interesting stuff
Sir Samuel Griffiths Centre – hydrogen fuel cell facility
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Imported European equipment – modifications required for Australian
standards
Some of the interesting stuff
Laboratory – Chemical Waste Collection System
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Dispersion modelling to reduce zone extents
Some key takeaways….
1. If you have a hazardous area installation, get competent
personnel involved early – this saves changes later which
are more expensive
2. Use the risk control hierarchy to reduce the size of the
zones or the equipment installed within them
3. Hazardous areas is a specialist area – if you want to work in
this area, get trained and competent
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Further Information
Standards Australia Publications
• HB13 – Handbook: Electrical equipment for hazardous areas
• AS/NZS 60079.10.1 – Explosive atmospheres Part 10.1:
Classification of areas – Explosive gas atmospheres
• AS/NZS 60079.10.2 – Explosive atmospheres Part 10.2:
Classification of areas – Combustible dust atmospheres
• AS/NZS 60079.14 – Explosive atmospheres Part 14: Electrical
installations design, selection and erection
• AS/NZS 60079.17 – Explosive atmospheres Part 17: Electrical
installations inspections and maintenance
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Questions?
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