hazardous area terminology

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Hazardous Area Terminology

Certification Standards

Expos products are certified to international standards for the installation and use of

electrical equipment in hazardous areas.

Worldwide: The IEC defines the most!idely adopted hazardous area standards. These

standards:

Classify hazards"

Areas #$ones% in !hich hazards may &e present"

'rotection used to pre(ent explosions in these areas #IEC )**+, series%.

-any countries are replacing national standards and certification schemes !ith IECEx

conformance and require IECEx certification:

Europe: Expos products are certified to E/ IEC standards under the ATE0scheme. 1e ha(e full 2rd party appro(al under the rele(ant 3irecti(es and our

-anufacturers 3eclaration of Conformity to European 4tandards #CE mar5ing%.

Brazil: Expos products ha(e I/-ET67 certification to IEC standards.

Australia & Singapore: IECEx certification is already mandatory.

North America: the /8'A #/ational 8ire 'rotection Association% is the primary agency for

the protection of installations from fire and explosion.

NFPA!is the /ational Electrical Code #/EC%. It descri&es permissi&le electrical

installations for residential commercial and industrial uses.

Article "!! !ithin the /EC. This categorizes hazardous locations 9 materials as

3i(isions and Classes. Article "!"is a later addition. This classifies hazardous locations into $ones 9

roups follo!ing IEC guidelines.

NFPA#$%is the 4tandard for 'urged and 'ressurized Enclosures for Electrical

Equipment.

Expo Technologies products are certified #listed% through appro(als &y c;


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roups: the flamma&le nature of the material.

In >,,? Canada introduced the @$one system for ne! hazardous area plants.

Worldwide: The classification of hazardous areas #locations% follo!s the IEC format:

$ones" define the pro&a&ility of the presence of flamma&le materials"

'rotection Types: denote the le(el of safety for the de(ice"

roups: classify the exact flamma&le nature of the material. /B. IEC groups are not

the same as the ;4As /EC roups.

'()atings

8or &oth IEC and /EC Tratings indicate the apparatus maximum surface temperature

under normal operation and specified fault conditions. The equipments Trating must &e

lo!er than the hazardous materials ignition temperature in that location.

The surface temperature is &ased on =*C #>*=8% am&ient. The

IEC has T> #=D*C% through T) #?DC%"

/EC uses the same principles &ut has more su&di(isions e.g. T2A T2B T2C.

E*plosion Protection 'echni+ues

The follo!ing descri&es explosion protection techniques to ena&le the use of electrical

equipment in hazardous areas.

/ational or international standards and codes of practice go(ern each technique and

define the equipments design and application.

/ational certifying #or appro(als% authorities ensure design compliance.

/ational inspectorates #or insurance companies% (et and usually inspect each

installation.

Flameproof ,E* d-IECFEuropean Harmonized 4tandard )**+,>

An enclosure contains the equipment. This enclosure !ill: 1ithstand an internal explosion of flamma&le gas or (apour that may enter it"

1ithout suffering damage"

1ithout communicating the internal flammation to the external explosi(e atmosphere

through any Goints or structural openings.

The enclosure is designed for a particular gas grouping #I IIA IIB or IIC%. Equipment using

this protection method is:

-ar5ed Ex d"

4uita&le for $one > and $one hazardous areas.

;sually Ex d equipment is large and ro&ust !hich limits its application to components.

.ntrinsic Safet/ 0 E* ia 1 E* i2 1 E* ic IECFEuropean Harmonized 4tandard )**+,>>

This protection technique restricts the electrical energy !ithin the equipment and

interconnecting !iring. The energy is so restricted that it cannot cause ignition &y spar5ing

or heating.

Equipment in the hazardous area and the connected apparatus in the safe area must &e

certified as intrinsically safe. Also the !hole system including interconnecting !iring must &e


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assessed as @safe. Certified independent &odies generally e(aluate equipment. The user is

responsi&le for system assessment.

The su&types aF&Fc define the equipments suita&ility for $one * $one > or $one . The

difference is performance under fault conditions:

Ex ia systems are safe e(en !ith faults"

Ex i& systems are safe !ith > fault"

Ex ic systems are safe in normal operation #no fault%.

Intrinsic safety is limited to lo! po!er circuits. It is mainly used for instrumentation and

exposed measurement de(ices.

Pressurization ,E* p-IECFEuropean Harmonized 4tandard )**+,

This protection method uses the pressure of a protecti(e gas to pre(ent explosi(e gases or

dust entering a space that might contain an ignition source. If that space contains

equipment that emits gas it pre(ents an explosi(e atmosphere &y using a continuous flo!

of protecti(e gas to dilute the atmosphere.

Equipment using this protection method is: -ar5ed Ex p"


.ncreased safet/ ,E* e-IECFEuropean Harmonized 4tandard )**+,+

This protection method applies additional measures to electrical apparatus !hich reduce

the possi&ility of excessi(e temperatures or arcs and spar5s.

Equipment using this protection method is:

-ar5ed Ex e"


3il immersion ,E* o-IECFEuropean Harmonized 4tandard )**+,)

This protection method immerses electrical apparatus in oil so an explosi(e atmospherea&o(e the oil or outside the enclosure !ont ignite.


-ar5ed Ex o"


Powder filling 4sand filling5 ,E* +-IECFEuropean Harmonized 4tandard )**+,D

This protection method fills the enclosure surrounding the electrical apparatus !ith granular

material e.g. sand. Hence an arc !ont ignite the explosi(e atmosphere.


-ar5ed Ex q"


Encapsulation ,E* m- IECFEuropean Harmonized 4tandard )**+,>?

The protection method encapsulates parts that could create spar5s or hot surfaces !ith a

compound. The compound pro(ides a &arrier &et!een the electrical apparatus and the

explosi(e atmosphere.


-ar5ed Ex ma and is suita&le for $one *"


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-ar5ed Ex m& and is suita&le for $one >.

'/pe N normall/ non(spar6ing and1or non(incendi7e circuits ,E* n-IECFEuropean

Harmonized 4tandard )**+,>D

This protection means in normal operation electrical apparatus !ont ignite a surrounding

explosi(e atmosphere. In addition a fault is unli5ely to cause ignition.

There are four types of Ex n appropriate for $one areas:

Ex nA: /on4par5ing apparatus"

Ex nC: /onincendi(e sealed encapsulated apparatus"

Ex n< for Energy


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Group E 'etal ust

Group F Coal ust

Group G Grain ust

Apparatus 'emperatureclassification #T class%

Maximum surface temperature Temperature class

)*+C (-) F !/

0++C (*1 F !

-+C (*02 F !#

2+C (*++ F !3

0+C ())2 F !C

/*C ()/4 F !

++C (04 F !0

/-+C (0*2 F !0#

/2*C (04 F !03

/2+C (0+ F !0C

/0*C (1* F !)

/+C ()- F !)#

/++C (/ F !*

-*C (/-* F !2

/orth America Hazardous


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Zone 0 !ases"

Zone 20 #usts"

Flammable material present continuously or for long periods (typically

/+++ hours or more per year

Zone 1 !ases"

Zone 21 #usts"

Flammable material present in normal operation (typically bet"een /+

and /+++ hours per year

Zone 2 !ases"

Zone 22 #usts"

Flammable material present in abnormal conditions only (typically less

than /+ hours per year

E*plosion 9roups

T$pical !as %a&ar#IEC '00()*0

E+,-.EA/ E/ '00()*0

#cetylene, $ydrogen IIC

&thylene II3

5ropane II#

Apparatus temperatureclassification #T class%

Maximum surface temperature IECE+,-.EA/ Temperature class

)*+C !/

0++C !

++C !0

/0*C !)

/++C !*

-*C !2

Protection ethods & Standardsfor roup II Electrical Apparatus for gas atmospheres

.rotection

Met%o#

Co#e

Ex

ATE

CAT

E/

IEC

.ermitte#

Zone T$pical Applications

Comments0 1 2

General

6equirements2++147+

3asic electrical 8 mechanical

requirements

9il Immersion o 2++1472 :es :es!ransformers, starting

resistors


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5ressuri%ed p 2++147 :es :es

;"itchgear and control

cabinets, analy%ers,

large motors

5o"der filled q 2++147* :es :es!ransformers, capacitors,

heating conductor terminals

Flameproof d 2++147/ :es :es

;"itchgear and controlgear,

indicating equipment,

transformers, light fittings,

motors, heating equipment

Increased

safetye 2++1471 :es :es !erminal 8 connection boxes

Intrinsic safety

iaia /

2++147

//:es :es :es

;afe "ith faults.

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