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8/13/2019 Pump Clinic 44

1/7Pump Clinic 44 Hazardous Areas August 2010 Page 1 of 7

Hazardous Areas

Hazardous area information is divided into the following sections:

1. Classification2. Protection Techniques3. Equipment Selection4. Aust ralian Standards5. Main Features

This information is of a general nature only and not to be relied upon for total accuracy. Readers mustmake themselves fully aware of the specific requirements of all relevant Australian Standards and otherstatutory requirements.

Section 1 Classification

This section refers to the requirements of Australian Standards and is intended to provide a quickreference for some common aspects of hazardous area classification in gas zones 0, 1 & 2.

For more detailed explanations of the requirements and responsibilities regarding installations inhazardous areas, consult the relevant standards.

In Australia, the following standards refer to classification of hazardous areas:

Gas - AS 2430.1 Dust - AS/NZS 61241.3

A Hazardous Area is defined by four main criteria, these being:1) The type of hazard (class)2) The likelihood of the hazard being present in flammable concentrations i.e. how hazardous is it

(zones)3) What is the hazard (group)4) The auto-ignition temperature of the hazardous material (temperature or T rating)

Classifi cation Example: ClassIZone1GroupIIATempClassT31) What type of hazard? (Class)

Class Hazard Remark

I GasesFlammable/explosive

gas mixtures

Dusts Combustible dusts

Note:Australia is aligning with IEC Standards and Classes are beingreplaced by Zones 0, 1 & 2 for gases and Zones 20, 21 & 22 for dusts.

2) How hazardous is i t? (Zone)

Grade of Release Description Gas Zone Dust Zone

Continuous: Source of releaseis continuous or frequent duringnormal operation

A hazardous atmosphere is continuously orhighly likely to present or present for longperiods of time (>1000 hours per year)

0 20

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Primary: Source of release isperiodical or occasional duringnormal operation

A hazardous atmosphere is possible butunlikely to be present for long periods of time(>10


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Section 2 Protection Techniques

This section refers to the requirements ofAustral ian Standards andis intended to provide a quickreference for some common protection techniques.

For more detailed explanations of the requirements and responsibilities regarding installations in hazardous areas,consult the relevant standards in your country.

Protection Philosophy Suitable Techniques Remark

Ex'd' FlameproofContainment ofExplosion

Ex'nC' Non-Sparking, Enclosed-break Devices

Ex'h' Hermetic SealingRarely permitted inAustralia. No AustralianStandard.

Ex'm' Encapsulation

Ex'nR' Non-Sparking, Restricted Breathing

Ex'nZ' Non-Sparking, Pressurisation

Ex'o' Oil ImmersionRarely used in Australia.No Australian Standard.

Ex'p' Pressurisation

Ex'q' Sand/Powder/Glass FilledRarely used in Australia.No Australian Standard.

ExclusionofHazardousMaterial

DIP Dust Ignition Protection For zones 20, 21 & 22 only

Ex'e' Increased SafetyPreventionofSourceofIgnition

Ex'nA' Non-Sparking

Ex'i' Intrinsic SafetyLimitationofIgnitionEnergy

Ex'nL' Non-Sparking, Energy Limiting

DilutionofGasAtmosphere Ex' v ' VentilationNote:Ex's' (Special Protection) may also apply to equipment that does not comply with the techniques describedabove, but may be suitable for use in hazardous areas.

3. Equipment Selection

This section refers to the requirements ofAustral ian Standards andis intended to provide a quickreference for the correct selection of equipment in gas zones 0, 1 & 2 (this page does not address dustzones 20, 21 & 22).

For more detailed explanations of the requirements and responsibilities regarding installations inhazardous areas, consult the relevant standards in your country.

In Australia, refer to AS/NZS 2381 for the selection, installation & maintenance of electrical equipment inhazardous areas.

Selection of Suitable Protection Technique for the Zone

Class Zone Permitted Protection Techniques Possible Application

Ex'ia' Intrinsic Safety (2 fault tolerant) Instrumentation & process control equipmentI 0

Ex's' Special Protection (certified for Zone 0) Gas detectors, analysers

Zone0protectiontechniques,plusthefollowingEx'd' Flameproof Power equipment, motors, high intensitylighting

Ex'ib' Intrinsic Safety (1 fault tolerant) Instrumentation & process control equipment

I 1

Ex'p' Pressurisation (certified for Zone 1) Control rooms, analyser houses, motors


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Ex' v ' Ventilation (certified for Zone 1) Switchrooms, laboratories, analyser houses


Ex'm' EncapsulationSolenoids, coils, electronics, proximityswitches

Ex'e' Increased Safety Junction boxes, light fittings, motors

Ex'o' Oil Immersion Control, signal & communication equipment

Ex'q' Sand/Powder/Glass Filled Signalling devices, plant telephonesZone1protectiontechniques,plusthefollowing

Ex'n' Non-Sparking Equipment (Non-Incendive) Junction boxes, light fittings, motors

Ex'p' Pressurisation (certified for Zone 2) Control rooms, analyser houses, motors

Ex' v ' Ventilation (certified for Zone 2) Switchrooms, laboratories, analyser houses

I 2


Selection of Suitable Temperature Classification

T Class Maximum Surface Temperature

T1 450oC

T2 300oC

T3 200oC

T4 135oC

T5 100oC

T6 85oC

Note:Applicable for an ambient temperature of 40oC.

Remember:Equipment must have an equal or higher temperature class(T1-T6) than the classification of the hazardous area.

Example:A T5 certified switch can be used in areas classified as T1 to T5,but cannot be used in an area classified as T6.

Selection of Suitable Gas Group

Gas GroupSubdivision

Permitted Gas GroupSubdivision

IIA IIA, IIB or IIC

IIB IIB or IIC only

IIC IIC only

Other Considerations

Other considerations when selecting electrical equipment for use in hazardous areas might include thefollowing:

Cost effectiveness with regard to purchase, installation and ownership

Maintenance requirements

Resistance to conditions (process, mechanical, environment)

Standardisation (can improve cost effectiveness, maintainability and ultimate safety)

4. Australian Standards

This section refers to some of theAustral ian Standards that govern the certification and installation ofelectrical equipment in hazardous areas and reference the corresponding IEC standards.


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For more detailed explanations of the requirements and responsibilities regarding installations inhazardous areas, consult the relevant standards in your country.

In Australia, refer to AS/NZS 2381 for the selection, installation & maintenance of electrical equipment inhazardous areas.

Protection Technique Standards

Aust ral ian Standards Protection TechniqueCertification Installation

IECStandards

Ex'd' Flameproof AS 2380.2 AS 2381.2 60079-1

Ex'e' Increased Safety AS 2380.6 AS 2381.6 60079-7

Ex'i' Intrinsic SafetyAS 2380.7 or

AS/NZS 60079.11AS 2381.7 60079-11

Ex'm' Encapsulation AS 2431 60079-18

Ex'n' Non-Sparking AS 2380.9 AS 1076.7 60079-15

Ex'o' Oil Immersion AS/NZS 60079.6 60079-6

Ex'p' Pressurisation AS 2380.4 AS 2380.4 60079-2

Ex'q' Sand/Powder/Glass Filled AS/NZS 60079.5 60079-5

Ex's' Special Protection AS 1826 AS 1076.8

Ex' v ' Ventilation AS 1482 AS 1076.13

General RequirementsAS 2380.1 or

AS/NZS 60079.0AS 2381.1 or

AS/NZS 60079-060079-0

5. Main Features

This section refers to the requirements ofAustral ian Standards andis intended to provide a quickreference for some of the basic construction features and installation requirements for the most commonprotection techniques (however there may be other precautions or restrictions that apply to yourinstallation).

Refer to the appropriate standards in your country for detailed construction and installation requirementsfor the various protection techniques.

Installation requirements applicable toALLprotection techniques include:

(a) Read the hazardous area compliance certificate, especially any Conditions of Use.

(b) All enclosure interfaces, eg, cable or conduit connections, must maintain the integrity and ratingof the enclosure.

(c) All circuits feeding into hazardous areas must be correctly isolated.

(d) Correct earthing is essential, including equipotential bonding, instrument and protective earthing.Depending on your installation, you may also require lightning protection, intrinsically safeearthing, cathodic protection, static protection, etc.

(e) Correct circuit protection (overcurrent, earth leakage, phase reversal, etc as appropriate) mustbe used.

Ex'd' Flameproof Robust construction. Be able to withstand, without damage, an internal explosion.

Presence of precision machined flamepaths, which are designed with a minimum flame leakagepath (FLP) and a maximum experimental safe gap (MESG) to quench the flame and cool hotgases before reaching the external explosive atmosphere.

Ensure suitable layout and spacing of internal components to avoid pressure piling.

Avoid invasion of flamepath by maintaining minimum 40mm clearance to other

structures/obstructions. Use non-flammable grease used on flamepaths (silicon, lanolin, etc).

Minimum 5 threads (tapered threads) or 8 (parallel threads) must be engaged on all flamepaths.

Running couplings/nipples not permitted (unable to verify number of threads engaged).


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Ex'e' Increased Safety Quality construction with minimum impact resistance of 7nM and minimum IP rating of IP54.

Minimum creepage & clearage distances.

Maximum surface temperature limits (assisted by restricted electrical loadings and minimumenclosure volume).

Limited quantities and ratings of terminals in junction boxes.

Where more than 1 component makes up the equipment, such as a junction box with terminals,all components must be individually certified (component certificate numbers will have a Usuffix).

Restrictions on permitted alterations (consult with manufacturer if changes required).

Minimum core sizes

All unused terminals to be screwed tight.

If at full current, do not bunch more than cores together.

Earth fault protection required on motors (generally alarm in Zone 2 or shutdown in Zone 1)

Ex'i' Intrinsic Safety Exia 2 fault tolerant, suitable for Zone 0

Exib 1 fault tolerant, suitable for Zone 1 (not Zone 0)

Allows for the use of non-certified simple devices, maximum 1.2V, 100mA, 25mW

I.S. barriers are required for all I.S. circuits (including simple devices in Australia)

I.S. barriers located in safe area (or protected using a different technique) Segregation required between I.S. and Non-I.S. components

I.S. components generally marked in BLUE colour

Shunt Diode Barriers (using zener diodes) require high integrity earth, but Isolated InterfaceBarriers do not.

Calculations generally required to match components and cabling when using individuallycertified components ("Entity Concept")

An entire system may be certified together, including all components and cabling ("IntegratedSystem")

Ex'm' Encapsulation A protection concept whereby equipment that could potentially cause an ignition is encapsulated

within a compound or resin so as to prevent contact with the explosive atmosphere. The concept also limits the surface temperature of the equipment under normal operating

conditions.

Ex'n' Non-Sparking Equipment that has the potential to arc is not capable of igniting a surrounding explosive

atmosphere.

This can be further categorised as follows:- Ex nA -Where components used in construction are non-sparking- Ex nC -Where components used in construction are non-incendive- Ex nR Where components used are tightly enclosed to restrict the breathing and

prevent ignition- Ex nL -Where components used in construction do not contain enough energy to cause

an ignition

Ex'o' Oil Immersion All equipment that has the potential to arc and potentially cause an ignition is immersed in a

protective liquid or oil.

The oil provides an insulating method to prevent ignition.

Ex'p' Pressurisation Enclosure must be purged or proven to be gas-free prior to energisation.

Separate protection techniques are required for support equipment (such as purge control unit,pressurisation accessories, gas detector, etc).

Protected enclosure must maintain a minimum pressure of 300 pascal or 50% higher than themaximum working pressure, whichever is the greatest.

Low pressure alarm sensor set at 50 pascal


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Ex'q' Powder Filling All equipment that has the potential to arc is contained within an enclosure filled with quartz or

glass powder particles.

The powder filling prevents the possibility of an ignition.

Ex's' Special This method of protection, as its name indicates, has no specific parameters or construction

rules.

In essence it is any method of protection which can provide a pre-determined level of safety toensure that there is no potential for an ignition.

As such it does not fall under any specific protection method and may, in fact, be a combinationof more than one.

Ex'v' Ventilation Gas or vapour released into the atmosphere can be diluted by dispersion or diffusion into the air

until its concentration is below the LEL.There are two types of ventilation available:

- Natural ventilation- Artificial ventilation, general or local

Natural ventilation is created by the movement of air caused by the wind and/or by temperaturegradients.

Artificial ventilation is provided by artificial means, e.g. fans or extractors. With the use of artificial ventilation, it is possible to achieve:

- Reduction in the extent of the zone- Shortening of the time of persistence of an explosive atmosphere- Prevention of the generation of an explosive atmosphere

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