Presentation Hazardous Area Classification.pdf

Hazardous Area Classification for Design

1. Hazardous Area
Classification

2. Introduction
Fire,ExplosionsandEnvironmentalPollutionarethemostserious
“unpredictable"issuesaffectinglifeandbusinesslossesinthehydrocarbon
andchemicalindustriestoday.

3. Fire and Explosion Fundamentals
•What is Fire?
•Flammable Hazardous Material
•Fire Triangle and Fire Tetrahedron
•What is an Explosion?
•Properties of Hazardous Materials

4. What is Fire?
Fire
Isarapidoxidationprocesswhichisa
chemicalreactionresultingintheevolutionof
heatandlight.

5. Flammable or hazardous material
•FlammableMaterialcanbegas,vapor,liquidorsolidthatcanreact
continuouslywithoxygenandmayresultinfireorexplosion.
•ThisreactioncanbeinitiatedbySparkorHotSurfaces
•FlammableMaterialscanbe:
•Flammablevaporsgeneratedbyliquid
•FlammableMists
•FlammableGases
•CombustibleDusts
Paint
Flammable
Vapor

6. Fire Triangle
Fuel
Heat
Oxygen
All three elements must be
present to initiate a fire.

7. Fuel
Heat
Oxygen
Chemical reaction
Fire Tetrahedron

8. Maybethecombustible
material.Canbesolid,liquid
orgas
Thosematerialsthatyield
oxygenorotherOxidizing
gasesduringthecourseof
achemicalreaction.
Heat istheenergy
component needed to
increase the fuel’s
temperaturetothepoint
wheresufficientvaporsare
producedforignitionto
occur.
Thechemicalchainreaction
knownasfireoccurswhen
fuel,oxygenandheatare
presentintheright
conditionsandamount.
FUEL OXIDIZING AGENT (O 2) HEAT
CHEMICAL CHAIN
REACTION
Fire Tetrahedron

9. What is an Explosion?
Explosion
isanuncontrolledreleaseofenergy
accompaniedbyasuddenand
violentexpansionofgasesand
possiblyrapidcombustionofany
flammablematerialspresent.

10. Explosion

11. Properties of Hazardous Materials
Flammability Range
The minimum or maximum concentration
of gas in air that will ignite.
Lower Flammability Limit
The lowest concentration at which a
fuel/air mixture will burn. Below this there
is too little fuel (the mixture is too lean)
Upper Flammability Limit
The highest concentration at which a
fuel/air mixture will burn. Above this there
is not enough oxygen (the mixture is too
rich)

12. Properties of Hazardous Materials
Flash Point
Theminimumtemperaturetowhichaliquidfuelgivesoffsufficientvaporthat
canbeignitedmomentarilybyaflame.
Fire Point
Theminimumtemperaturetowhichaliquidfuelgivesoffsufficientvaporto
supportcontinuouscombustion.
AutoIgnitionTemperature
Theminimumtemperatureatwhichaliquidfuelwillignitewithoutthepresence
ofapilotflameorspark.

13. What is Hazardous Area?
Theareainwhichanexplosivegas
atmospherepresentorlikelytobe
presentinquantitiessuchasto
requirespecificprecautionsfor
construction,installationanduseof
electricalapparatus.

14. HAC is Defined by three main criteria:
What is Hazardous Area?
Type of the hazard ( gas , vapor, dust, fibers)
Likelihoodof the hazard being present in
flammable concentrations
The Auto Ignition Temperature of the
hazardous temperature.

15. Why do we classify Hazardous Areas?
•Ifproperareaclassificationandsafetyengineeringpracticesarefollowed
whileworkinginthoseareaswecangreatlyreducetheriskoffireand
explosionshazardsintheseplaces.
•Allelectricalequipmentproduceenergyintheformofsparkswhichcan
ignitethesehazardousmaterialsandorcauseexplosionscausing
catastrophicdamage.
•Inhazardousareaweusespecialpurposeexplosionprotectedelectrical
equipmentandinstruments.

16. Concept of Classification
•HazardousAreaClassificationistobedonefortheareasoftheplantthat
wouldhaveinstancesofflammablemixturesofvapors,gasesordustsin
normaldaytodayoperations.
•Underunusualconditionslikeacatastrophicaccidentalreleaseoflarge
quantityofinflammablewhicharenoteasilypredictable.
•Underusualdaytodayoperationalconditionsintheplantorfacilitythere
aresomeareaswhichwouldhavethepresenceofflammablemixturesof
vaporsandgasese.g..Vaporspaceinthestoragetank,arounda
mechanicalsealofapump,theareaaroundsurroundingthebreathing
valveonthestoragetank.

17. Basic concepts
•What is Hazard?
•What is Risk?
•Can we avoid the risk altogether?
•Area classification –a measure of the risk
•Area classification benefits.
•How does Area Classification work?
•How can area classification reduce the costs?

18. HAZARD & RISK
Hazard
isthesourceofpotentialdamage,harmor
adversehealtheffects.Ahazardcanexist
withoutincurringanyharm.
NO EXPOSURE: NO RISK
21

19. What is the risk?
•Is the measure of likelihood that the undesired event or accident
will actually occur

20. Can we avoid the risk altogether?
•It is not possible in the world without some amount of risk

21. Hierarchy of Control

22. •Sincewecannotavoidtheriskwecanmanageitinalogicalway.
•Sincewehavenocontrolovertheseverityoftheconsequence,we
reducetheotherfactorintheriskequationwhichistheprobabilityof
theoccurrence.
•Inthesamewaywemanagetheriskofhandlingandstoringlarge
amountsofflammableandexplosivematerialsbyareaclassification
whichreducetheprobabilityofthematerialscatchingfireor
explosion.
Can we avoid the risk altogether?

23. Area classification -A Measure of the Risk
•HazardousAreaClassificationprovidesa
profileoftheriskofexplosionintheseareas.
•ItCannotpredictdefinitivelythatanexplosion
willorwillnottakeplaceinthatarea.
•Itonlysegregatestheplantareasintoareas
wherethelikelihoodofanexplosionishighand
areaswherethelikelihoodisloworimprobable.
•Theclassificationprovidesusatooltomitigate
theriskofexplosioninsuchareas.

24. How Does Area Classification Works ?
•Identifywhichareasoftheplantaremorehazardousandneed
specialattentionorequipment.
•Identifyareasoftheplantcarrymorerisksthanothers.
•Areaclassificationallowstheoperationsmanagersto
mitigatetheserisksbytakingappropriatesafetymeasuresin
eachidentifiedareasandreducetheoverallriskofthefacility
•Designoperations,materialandstaffmovementtorestrict
accesstotheseareasandhavespecialworkproceduresfor
theseareas.

25. Area Classification Benefits
•Giveusariskprofileoftheplantorfacilitytoenableustooperateit
safer
•Enablestopmanagementtoreallyunderstandtherealriskofthefacility
andthencomeupwithappropriatestrategiestomitigatetherisk.
•Enableustodesignandinstallelectricalinstrumentationandcontrol
systemequipmentthatwillnotcausefiresorexplosionsattheoptimumcost
•Reducethecostsofcompliancetoregulationsandstandardswithout
compromisingonthesafety
•Maketheoveralloperationssaferandmoreprofitable

26. How Area Classification Reduce Costs?
•Ittellsuswhatkindofequipmentcanbeusedintheareaand
whattypecannotbeused.
How
•Putexplosionprotectedelectricalequipmentdesignedfor
useonlyincertainarea.
•Theequipmentcarrymarkingwhichtellsweatheritcan
beusedornot.
•Basedonthisitwillbesafelyusetheequipmentinthatarea
withoutanyworry.
•Therewouldbesomeelectricalequipmentandinstruments
thataresuitableforuseonlyinzone2whereascertain
othertypescanbeusedsafelyinzone1

27. Standards for Area Classification
•European System /IECSystem ( Zones & Groups )
•North American System (NEC) ( Classes & Divisions )
IEC: International Electrotechnical Committee.
NEC: National Electric Code.

28. Standards for Area Classification
European System /IEC System
•TheEuropeanSystemisbasedonzones
•EveryHazardousAreaisbrokenupintodifferentzones
basedonthelikelihoodofahazardousgas/vapormixture
beingpresent.

29. European System /IEC

30. European System /IEC

31. Examples

33. Examples

34. European System (ZONES)

35. ZONES(CONT.)

36. ZONES(CONT.)

37. ZONES(CONT)

38. ZONES(CONT.)

39. ZONES(CONT.)

40. ZONES(CONT.)

41. ZONES(CONT.)

42. ZONES(CONT.)

43. ZONES(CONT.)

44. ZONES(CONT.)

45. ZONES(CONT.)

46. ZONES(CONT.)

47. ZONES(CONT.)

48. ZONES(CONT.)

51. Floating roof tank

53. Openings classification
•Openings are classified as A, B, C, D with the following characteristics:
•Type A –Openings not conforming to the characteristics specified for types B, C or D
•Examples:
•open passages for access or utilities, for example, ducts, pipes through walls, ceilings and
floors;
•fixed ventilation outlets in rooms, buildings and similar openings of types B, C and D which
are opened frequently or for long periods.

54. Openings classification(cont.)
•Openings are classified as A, B, C, D with the following characteristics:
•Type B –Openings which are normally closed (for example, automatic closing)
and infrequently opened, and which are close-fitting.

55. Openings classification(cont.)
•Type C –Openings normally closed and infrequently opened, conforming to type B,
which are also fitted with sealing devices (for example, a gasket) along the whole
perimeter; or two type B openings in series, having independent automatic closing
devices.

56. Openings classification(cont.)
•Openings are classified as A, B, C, D with the following characteristics:
•Type D –Openings normally closed conforming to type C which can only be opened
by special means or in an emergency.

61. IEC Gas Grouping
II C
DANGER
II BII A
Under IEC system Materialsare classified under various Groups as
follows :
GroupI:Miningapplications
(undergroundminescontainingfiredampthe
minegasthatcompromisedmainlyof
Methane)
GroupII::(surfaceindustry)
FlammableGaseslikehydrogen
propane..etc.flammablevapors
likeacetone,benzeneetc.Group
IIissubdividedintoA,B,C

62. IEC Gas Grouping

63. North American System/ NEC
•This system consists of Classes , Divisions & Groups:
ClassI:locationsinwhichflammablegases,
flammableliquids-producedvaporsareormaybe
presentintheairinquantitiessufficienttoproduce
explosiveorignitablemixtures,
Class II :locations that are hazardous
because of present of combustible dust.
ClassIII:locations that are hazardous
because of the presence of easily ignitable
fibers.

65. NorthAmerican System/NEC
•The NEC System is based on Divisions
Division 1
•Inwhichignitableconcentrationsofhazard
existsundernormaloperationconditions
and/orwherehazardiscausedbyfrequent
maintenanceorrepairworkorfrequent
equipmentfailure.
Division 2 •Inwhichignitableconcentrationsofhazardare
handled,processedorused,butwhichare
normallyinclosedcontainersorclosed
systemsfromwhichtheycanonlyescape
throughaccidentalruptureorbreakdownof
suchcontainersorsystems.

66. North American System
•IntheNorthAmericanSystemeachClasshasseveral
Groupsunderit.

67. Material Classification under the two systems

69. Temperature Classification
Why This Is Necessary ?
As a hot surface can provide sufficient energy to ignite flammable mixtures
of vapors , gases or dusts in the hazardous area.
IEC North America /NEC

71. Protection Techniques
Popular Types
Exd:Flame/Explosion Proof
Exi: Intrinsically safe
Exe: Increased safety
Exn: No-sparking
Exp: Pressurization
Not -Popular Types
Exq:Powder Filled
Exo: Oil Immersed

72. Protection Techniques
Flameproof enclosure “ d ”
•is totally enclosed construction.
•When gas or vapor get into the enclosure and an
explosion take place,
•the enclosure withstands the pressure of explosion
and,
•preventingtheignitionofaspecifiedgasorvapor
surroundingtheenclosurebysparks,flashes,or
explosionofthegasorvaporwithin,andwhich
operatesatsuchanexternaltemperaturethata
surroundingflammableatmospherewillnotbe
ignitedthereby.
Application:
switchgear,motors,MachineControlSystems

73. Protection Techniques
Increased Safety “ e ”
•IN case of INCREASED SAFETY CONCEPT
additional measures are applied to increase the level
of safety,
•thus preventing the possibility of high temperatures
and the occurrence of sparks or electric arcs within the
enclosure or on exposed parts of electrical equipment
•“Increased safety” increases the insulation
performance
Application :
Junctionboxes/terminalboxes-Lighting-Measuring
instruments-Transformers-Squirrelcagemotors

74. Methods of protection
The “e” Principal
insulated enclosure,
minimum IP 54
Excertifiedelectricalcomponents
(withelectricalconnectionsthat
cannotloosenbythemselves)
Protection Techniques

75. Methods of protection
“de” protection
Protection Techniques
•Mainlyjunctionboxeshave100%increasedsafety“e”
•Sparkingequipmentoftenincorporates“d”components
•Mostproductscommonlyreferredtoas“e”combinethe2typesof
protection“e+d”

76. Methods of protection
“de” products
also called «ed»
flameproof “d” chambers
“e” enclosure
16A plug and socket
Protection Techniques

77. Methods of protection
“de” products
also called «ed»
Control stations
Protection Techniques

78. Methods of protection
“de” products
also called «ed»
fluorescent luminaire
Protection Techniques

79. Methods of protection
stainlesssteel -“e” (junction box)
cabinet -“de” (control station)
“de” products
also called «ed»
Protection Techniques

80. Protection Techniques
Intrinsically safe “ i”
•Electricalsystem/apparatusanditswiringisnotcapableofrealizingsufficient
electricalorthermalenergyundernormalorabnormalconditionstocauseignition
ofaspecificflammableorcombustiblemixtureinitsmostignitableconcentrations.
Ex ia
Equipment that incapable of causing
ignition in normal operation with two
faults
Ex ib
Equipmentincapableofcausing
ignitioninnormaloperationwitha
singlefault
Intrinsically
safe “ i”
e.g. switch amplifier

81. Protection Techniques
Pressurization type “ p ”
•isatypeofprotectionbywhichtheentryofa
surroundingatmosphereintotheenclosureofthe
electricalapparatusispreventedbymaintaining,
•insidethesaidenclosure,aprotectivegasata
higherpressurethanthatofthesurrounding
atmosphere.
•Theoverpressureismaintainedwithorwithout
continuousflowoftheprotectivegas.
•Theprotectivegascanbeeitherair,inertgasoran
othersuitablegas.

82. Protection Techniques
Pressurization type “ p ”
Application:
•Large machines
•Switching and M&C panels
•Switch rooms & control centers
•Analysis & monitoring apparatus
•Special application solutions

83. Protection Techniques
No –sparking “n”
Itisapplicabletoelectricequipmentwhichisnotcapableofignitingpotentially
explosiveatmospheresundernormaloperation.
isthespecialexplosionprotectionconstructionforZone2orDivision2.

84. Protection Techniques
Powder Filled “q”
isatypeofprotectioninwhichtheenclosureoftheelectrical
apparatusisfilledwithamaterialinafinelygranulated
statesothat,intheintendedconditionsofservice,anyarc
occurringwithintheenclosureoftheelectricalapparatus
willnotignitethesurroundingatmosphere.
Noignitionshallbecausedeitherbyflameorbyexcessive
temperatureofthesurfacesoftheenclosure.
Application :
•Fuses
•Capacitors
•Electronic circuit boards -EVG

85. Protection Techniques
Oil immersion “o”
•isatypeofprotectioninwhichtheelectrical
apparatusorpartsoftheelectricalapparatusare
immersedinoil
•insuchawaythatanexplosiveatmospherewhich
maybeabovetheoiloroutsidetheenclosure
cannotbeignited.
Application :
•Switching units
•Circuit breakers
•Transformers

86. Protection Techniques
Encapsulation “m”
•isatypeofprotection,inwhichthepartsthatcould
igniteanexplosiveatmosphere,
•areenclosedinaresinsufficientlyresistantto
environmentalinfluences,
•insuchawaythatthisexplosiveatmospherecannotbe
ignitedeitherbysparkingorheatingwhichmay
occurwithintheencapsulation.
Application :
•Valves
•Electronic circuit boards
•Miniature motors

88. API 500 (American Petroleum Institute) using Division method
only for petroleum industries.
European Standards IEC using ZONING method for general
industries .
API 505 For Petroleum industry using zoning method.
North America using classes and divisions, Class I for Gas,
Class 2 for Dust and Class 3 for Fiberd.
Methods of classifying Hazardous area

89. CENELEC: European committee for electrotechnical standardization
Ex Marking

90. Ex Marking
ATEX MARKING SYSTEM
ATEX: Explosive Atmosphere

91. Installation rules
Methods of installation throughout the world
•wire,braidorsteel-tape
armouredcable.
•connectionusinganearth
continuitycablegland
•unarmoured cable
•connection using a cable gland
•conductorsplacedinsidea
rigidthreadedconduit
•connectionusingaseal

92. Installation rules
Multicore cables
Protection against mechanical shocks
• armoured cables
Or • cable ducting + installation clamps
Protection against chemical attack
• most industrial cables are suitable
Protection against fire
• minimum: cable which does not propagate flames
• ideal : cable capable of withstanding fire
Methods of installation throughout the world

93. Installation rules
Selecting cable inlets
The cable gland must:
•be adapted to the type ofthread of the product on which it is
mounted
•be Exeor Exdcertified
•have at least the same index of protection as the product on
which it is mounted
•be adapted to the cable diameter and type
•sometimes clamp the cable
Methods of installation throughout the world

94. Installation rules
Selecting cable glands
The cable gland must be certified:
• Exe if the enclosure is Exe or Exed
• Exd if the enclosure is Exd
IP of the cable gland ≥ IP of the product ( later will be explained)
Methods of installation throughout the world

95. Installation rules
Selectingcable glands
The cable gland must be matched to the cable type
• Cable diameter
• Cable .armoured
or .unarmoured
or .MICC
Mineral-insulated copper-clad cable
Methods of installation throughout the world

96. Selecting cable glands
The cable must be correctly clamped by means of the
cable gland
• Internal clamping system
• External clamping system
orby means of an installation clamp
Methods of installation throughout the world

97. cable clamp
Selecting
cable glands
“e” cable gland
• polycarbonate
• IP 67
• for unarmoured cable
Methods of installation throughout the world

98. Selecting
cable glands
“e” plastic cable gland
unarmoured cable
“ed” 16A 230V socket
Methods of installation throughout the world

99. Selecting cable glands
“ed” rotary switch
armoured cable
“e” cable gland for
an armoured cable
Methods of installation throughout the world

100. Installation rules
Selectingcable glands
cable clamping
rings
“e” cable gland for an armoured cable
and earth continuity
NB: this type of gland ensures the earth continuity of the armoured cable
Methods of installation throughout the world

101. Installation rules
Selecting cable glands
“d” cable gland
Methods of installation throughout the world

102. Installation rules
Selecting cable glands
seal
Compound
•The connection between the
conduit and the electrical
device is achieved using a
seal
•The connector is filled with a
sealing compound (to prevent
an explosion from spreading
through the conduits)
Methods of installation throughout the world

103. Installation rules
Advantagesofaninstallationwithcableglands
comparedtoaconduitinstallation
•More competitive prices
•No need to thread the conduits on site
•No generalized seals
•Easier maintenance, inspection and extensions
•Far fewer problems with corrosion
Methods of installation throughout the world

104. Conduit installation

105. Installationwith cable gland

106. What do you think?
EX !!!

107. What do you think?
EX !!!

108. Ingress Protection
•IPclassificationsystemdesignatesthe
degreeofprotectionprovidedbyan
enclosureagainstimpactandwateror
dustpenetration(ingress).
•Ithastwonumbers;
•First: Protectionagainstsolidobjects,
•second: Protectionagainstwater.

109. Ingres Protection
EXAMPLE:IP54

110. IP Rating

111. IP Rating

112. IP ratings

113. What if hazardous area is wrongly classified ?
Unnecessarily pay more money
More Maintenance Costs
Facility will incur more costs over its lifecycle.
Costcouldbehighastheymayresultinunwanted
explosionleadingtolossoflifeandproperty

114. API 500 (American Petroleum Institute) using Division method
only for petroleum industries.
European Standards IEC using ZONING method for general
industries .
API 505 For Petroleum industry using zoning method.
North America using classes and divisions, Class I for Gas,
Class 2 for Dust and Class 3 for Fiberd.
Methods of classifying Hazardous area

115. SUMMEERY
EuropeanSystem /IEC

116. North American System/ NEC
•This system consists of Classes , Divisions & Groups:
ClassI:locationsinwhichflammablegases,
flammableliquids-producedvaporsareormaybe
presentintheairinquantitiessufficienttoproduce
explosiveorignitablemixtures,
Class II :locations that are hazardous
because of present of combustible dust.
ClassIII:locations that are hazardous
because of the presence of easily ignitable
fibers.

117. North American System
•IntheNorthAmericanSystemeachClasshasseveral
Groupsunderit.

119. Temperature Classification
Why This Is Necessary ?
As a hot surface can provide sufficient energy to ignite flammable mixtures
of vapors , gases or dusts in the hazardous area.
IEC North America /NEC

121. CENELEC: European committee for electrotechnical standardization
Ex Marking

122. Ex Marking
ATEX MARKING SYSTEM
ATEX: Explosive Atmosphere

123. NEC Marking

124. Ingres Protection
EXAMPLE:IP54

125. How to carry out area classification?
Step by step
STEP 1 :
Decide on the standard that would be followed (IEC-NEC)
STEP2:
Checkoutthelayoutofthefacilityortheplant,thequantitiesthatare
handledintheprocessplant
STEP3:
whatisthematerialtemperatureclassificationofthesematerials?flashpoints,
autoignitiontemperature,densityofvapor/gas(lighterorheavierthanair)

126. How to carry out Area Classification?
Step by step
STEP 4 :
•Dividetheplantintodifferentunits
•Starttoevaluatethesourcesofreleaseofunit
•Classifythemascontinuousgrade,primarygradeorsecondarygrade
•Tabulatethemfindingsinaworksheetandmarktheseonthegeneral
arrangementdrawingoftheunit
STEP5:
Evaluateventilationinthearea(closedoropen)howdoesthewindgo?Doesthe
winddirectionremainthesameorchangedifthevaporcloudformed,howfarit
willtravelalongwiththewind?Arethereareanyplaceswhereescapedvapors
mayaccumulate

127. Sources of
release

128. How to carry out Area Classification?
Step by step
STEP 6 :
basedonthefindingsonstep4&5andthestandardyouarefollowing
markthehazardousareaonthedrawingstheseextentswillbe
surroundingthereleasepointsthathavebeenmarkedinstep4
STEP7:
Dividethehazardousareaintodivisionsorzones(dependingonthestandard
youareusing)

129. Consequence of Poor area classification
•Over Classification –White Elephant
•Under Classification –Playing with Fire
•Proper Area Classification is the virtuous in between

130. Over classification-A White Elephant
•Increasecapitalexpenditureonnewprojectsduetomore
expensiveequipmentbeingspecified
•Increaseoperationsandmaintenanceexpenditureofan
existingfacilityasreplacementpartswillbecomemoreexpensive
maintenanceworkpermitswillbestringentandtimeconsuming
leadingtohighercosts
•Unnecessarylabelyourfacilitydangerousinthelocal
community
•Increaseyourinsurancepremiums

131. Under classification –Playing With Fire
•IncreaseTheRisksofyourplantorfacilitywithoutanybody
knowingit,especiallythetopmanagement.
•Incaseofanunfortunateaccidentexposeyouandyour
companytolawsuits.
•Givelotofbadpresstoyourcompanyandeventhreatenits
existence

132. So now what do we do?
•ConductanAuditofyourFacility.
•MarkingHazardousAreaswithreferencetothecurrent
standards.
•TrainingpersonnelonthebasicsofHAC.