the quality systems in the field of explosion proof equipment

8/7/2019 The Quality Systems in the field of Explosion Proof Equipment

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specialist in ex-proof electrical equipment

introduces :

The Quality Systems inThe Quality Systems in

the field of Explosionthe field of ExplosionProof EquipmentProof Equipment



The Hazard TriangleThe Hazard Triangle

OXYG

EN

SPARK / IGNITION

EXPLOSIONEXPLOSION

C O M B U S T I B L E

G A S



Sources of IgnitionSources of Ignition• A source of energy is all that is needed to touch off an explosion

when flammable gases or combustible dusts are mixed in theproper proportion with air.

• Equipment :

switches

circuit breakers

motor starters

push button stationsplug/receptacles

Can produce arcs or

sparks in normaloperation when contacts

are open & close



What are Hazardous LocationsWhat are Hazardous Locations

• The identification of a danger zone in a chemical or

petrochemical plant should be carried out by highly qualifiedpersonnel. Normally process managers, who establish wherein the plant there is a presence of either a continuous oroccasional explosive atmosphere.

• The most frequent danger points are found where there is apossibility of inflammable gas leaks, that can occur duringnormal operation or due to a breakdown.

• The classification is determined by the quantity of gas present

in given zone.



Basic PrinciplesBasic Principles

• To define the various hazard zones in the interior of aplant (Zones/Groups)

• Flash point and self-inflammation temperature in ºc

for gases, self flammation temperature in layers or inclouds for dust

• To select the choice of electrical equipments that canbe installed in that zone to ward off the danger ofexplosions caused by accidental sparks or surfaceoverheating



The marking systemThe marking system

CE marking which certifies conformity

Notified Body identification code (e.g. : 0081 = LCIE)

Distinctive community marking

for equipment usable on potentially explosive atmosphere

Equipment Group (used in surface industry)

Equipment category (for Zone 1)

Gas and/or Dust

Temperature

class

0081 II 2 G e/o D T6 IP66

Example marking required by the new directive ATEX 94/9/CE

IP protection

degree

EEx-e

Method of

protection



CENELECCENELEC(European Committee for Electro Technical Standardization)

Some of specialized laboratories recognized by theEEC in Europe :

• BASEEFA U.K.

• LCIE France

• CESI Italy

• DEMKO Denmark

• ISSeP (INIEX) Belgium• KEMA Holland

• PTB Germany



Equipment GroupsEquipment Groups

Place of Use Group Areas Representative Gas

Minessusceptible tofiredamp

I Gaseous mines Methane

Surfaceindustries

II A Surface Propane

II B

II B + H2

Ethylene

Hydrogen

II C Hydrogen and orAcetylene



Hazardous Areas ClassificationHazardous Areas Classification



Equipment Categories andEquipment Categories andHazardous Areas ClassificationHazardous Areas Classification

equipment

category

hazardous

areasdescription

1 G ZONE 0 An area in which the mixture of explosive gas is constantlypresent (ex. The inside of fuel tank).

2 G ZONE 1

An area in which a mixture of explosive gas may be

present during the normal operation of the plant (max 10hours / year)

3 G ZONE 2An area in which the mixture of explosive gas is notnormally present, but is only present for brief periods oftime. (max 1 hour / year)

Gas / VapourGas / Vapour



Equipment Categories andEquipment Categories andHazardous Areas ClassificationHazardous Areas Classification

equipment

category

hazardous

areasdescription

1 D ZONE 20 An area in which the mixture of explosive powder isconstantly present (ex. Centrifugal dust separator).

2 D ZONE 21An area in which a mixture of explosive powder may bepresent during the normal operation of the plant (max 10hours / year)

3 D ZONE 22 An area in which the mixture of explosive powder is notnormally present, but is only present for brief periods oftime. (max 1 hour / year)

DustDust



ExplosionExplosion--proof Standardproof Standard““Method of ProtectionMethod of Protection””

General Rules Permitted inZone

Oil immersed Ex “o” Zone 1, 2

Inside Pressure Ex “p” Zone 1, 2Construction under sand Ex “q” Zone 1 ,2

Explosion-proof housing Ex “d” Zone 1 ,2

Increased Safety Ex “e” Zone 1 ,2

Intrinsic Safety Ex “i” Zone 0, 1 ,2

Encapsulation Ex “m” Zone 1 ,2




EEx-i

Intrinsic Safety

Designed to limit

the ignition energy

of the circuitZone 0 – 20 – 1 – 21 – 2 - 22




EEx-d

Explosion-Proof Housing-Contain internal explotion

-Explotion cannot transmitted outside enclosure

-Cabel fitting must have 5 treads engaged

Designed to contain theexplosion (flame) inside

the enclosure

Zone 1 – 21 – 2 - 22




EEx-eIncreased Safety

1.Must use high impact resistant materials

FRP/GRP will not hold static charge

2.Internal components cannot produce arcs or

sparks3.Has special air and line leakage and creapage

distances

4.Control internal and external temperature.

External <= 85 deg Cel (T6).

Designed to prevent

any ignition from

arising

Zone 1 – 21 – 2 - 22




EEx-qPowder Filling

EEx-mEncapsulation

EEx-pPressurization

EEx-oOil Immersion

Designed to prevent the flammable

Mixture reaching a mean of ignition Zone 1 – 21 – 2 - 22




EEx-n

Restricted Breathing “n” Equipment (Non Sparking)1.Equipment has no normally arcing parts

2.Enclosure restricts ingress of hazardous gases

3.Thermal effects incapable of ignition

Designed to preventany ignition from

arising

Zone 2 - 22



Temperature class T1 T2 T3 T4 T5 T6

Maximum Surface 450ºc 300ºc 200ºc 135ºc 100ºc 85ºc

TemperaturesTemperatures

HOT COOLER

T1 T2 T3 T4 T5 T6

T1 T2 T2 A T2 B T2 C T2 D T3 T3 A T3 B T3 C T4 T4 A T5 T6

450° 300° 200° 135° 100° 85°

450° 300° 280° 260° 230° 215° 200° 180° 165° 160° 135° 120° 100° 85°

Different temperature classification betweenDifferent temperature classification between U.E.U.E. andand U.S.A.U.S.A. standardsstandards



Classification of the Hazardous AreasClassification of the Hazardous AreasAmerican StandardAmerican Standard

Division 1 The danger can exist during normal operation

Division 2 The danger could exist only in case of breakdown

CLASS I Gas or Vapours (Groups A – B – C – D)

CLASS II Powders (Groups E – F – G)

CLASS III Fibers



Differences between the EuropeanDifferences between the Europeanand north America Methodsand north America Methods

Div. 2 – Class IDivision 1 – Class I

ZONE 2ZONE 1ZONE 0IEC / EUROPE

USA / CANADA

BREAKDOWNINTERMITTENTPRESENCE

COSTANTLYPRESENCE

Div. 2 – Class IIDivision 1 – Class II

ZONE 22ZONE 21ZONE 20IEC / EUROPE

USA / CANADA

BREAKDOWNINTERMITTENTPRESENCE

COSTANTLYPRESENCE

Note : The fibers – Class III – are still not specified by European Standards



Advantages & Disadvantages ofAdvantages & Disadvantages ofExEx ““dd”” and Exand Ex ““ee””

Advantages Disadvantages

EEx-d • capable of withholding a possible

internal explosion and prevent itstransmission to the atmosphereoutside the housing

• higher class of protection

• easily available and cheapercomponents

• maintenance more complicated

(e.g. difficult to change fluorescent tubes)

• piped plant (where requested)complicated

EEx-e • easy installation

• pleasant appearance• safety cut-off switch

• high cost of spare parts (components

must be Ex type)• frequent and costant maintenance

(e.g. seal)



Examples of ExplosionExamples of ExplosionProof EquipmentProof Equipment



EExEEx--dd

Junction boxes

EJB Series

Material: Aluminium

GUB Series

Material: Aluminium



EExEEx--dd

Distribution boards

Material: Aluminium – Stainless steel



Lighting fixtures

EExEEx--dd

RCDE

Material: Aluminium

EVFEVAC

EJB08



EExEEx--e / EExe / EEx--ii Junction boxes

Materials: GRP – Stainless steel - Aluminium



EExEEx--eded

SA/C

Lighting Fixture / Control Station


AVFMaterial: GRP



EExEEx--dede

CCAC

Lighting fixtures / Control stations / Distribution Boards

SFDEMaterial: Aluminium


(detailed view)



EExEEx--d / EExd / EEx--e / EExe / EEx--ii

Cable glands

Materials :

Nickelplated brass – GRP

Stainless steel – Galvanized steel



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the quality systems in the field of explosion proof equipment

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