Hazardous Area Classification

1. HAZARDOUS AREA CLASSIFICATION
Health, Safety & Environment
II 2G E Ex ib IIC T5

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Hazardous Area Classification 2
The need to know!
 Severe accidents in coal mines occurred
throughout the world in the 19th and 20th
century (thousands of casualties).
 Classified and unclassified areas
 Use of non-IS equipment
 Mobile phones
 Safety measures

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Hazardous Area Classification 3
Hazardous Area
 HA is defined as an area in which the
atmosphere contains flammable or explosive
gases, vapors or dusts.
 Includes such installations as oil/gas rigs,
processing refineries, chemical production,
flammable liquids storage, fuel transportation,
petrol station, Paint & paper production.

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Hazardous Area Classification 4
The fire triangle and what we can do about it
Controls

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Hazardous Area Classification 5
International
IEC International Electrotechnical Commission
E.g. IEC 60079-10
European
CENELEC European committee for Electrotechnical
standardization
E.g. EN 60079-10
US
NEC National Electric Code
(part of NFPA 70)
The standards

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Hazardous Area Classification 6
Classification -IEC and ATEX Standards
 The type of Hazard (Groups)
 The auto ignition temperature of the
hazardous material (“T” rating)
 The likelihood of the hazard being present
in flammable concentrations (Zones)

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Hazardous Area Classification 7
The Type of Hazard (Group)
 In the form of either Gas/Vapor/Dust/Fibre
 Two groups depending on Mining or above
surface industry
Group I – Electrical equipment for Mines
Group II – Electrical equipment for places with gas atmosphere
Group III – Electrical equipment for places with dust atmosphere

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Hazardous Area Classification 8
Auto ignition Temperature or “T” rating
 Temp. class is based on auto ignition temp.
of hazardous material
 Gas Groups (I, IIA, IIB, IIC)
 Dust Groups (IIIA, IIIB, IIIC)
 Temperature class (T1, T2, …… T6)

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Hazardous Area Classification 9
Zones
Gases and Vapors and Dust
 Amount of the time the hazardous is present
Safe Zone
Zone 2/22 - Gas or vapor is not likely to be present in normal
operation and for short period of time. (<10 hrs/year)
Zone 1/21 - Gas or vapor is possible but unlikely to be present for
long period of time. (>10<1000 hrs/year)
Zone 0/20 - Gas or vapor is highly likely to be present and for long
periods of time. (>1000 hours/year)

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Area Classification - Zones

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Hazardous Area Classification 11
Gas Groups
Gas
Group
Temperature Class
T1 T2 T3 T4 T5 T6
I Methane
IIA Acetone Ethanol Diesel Fuel Acetaldehyde
Methane Cyclohexane Artificial Fuel
Ethane Propanol 2 Fuel Oil
Benzene N-Butyl alcohol N-hexane
Methanol N-Butane Heptane
Toluene Kerosene
Propane
Acetic acid
Ammonia
IIB Coal Gas Ethylene Ethylene glycol Ethyl Methyl Ether
Ethylene oxide Hydrogen Sulphide
Propanol 1 Tetrahydrofuran
Methyl ethyl Ketone
Acetylene
IIC Hydrogen

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Hazardous Area Classification 12
Temperature Classes
T Code Maximum Surface Temperature
T1 450 °C
T2 300 °C
T3 200 °C
T4 130 °C
T5 100 °C
T6 85 °C

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Hazardous Area Classification 13
Auto ignition temperatures
Material
Temperature
(oC)
Acetaldehyde 175
Acetone 465
Acetylene 305
Gasoline 280
Hydrogen 500
Butane 420
Carbon 700

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Hazardous Area Classification 14
Protection Concept

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Hazardous Area Classification 15
Ingress Protection
The International Electro technical Commission
provides Ingress Protection (IP) ratings that are
used to determine the degree of protection
provided by an electrical enclosure.

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Hazardous Area Classification 16
What do the numbers represent?
IP6X
The first number designates protection against solid objects.
IPX8
The second number designates protection against water.

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Hazardous Area Classification 17

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Liquid Ingress Protection
Level Protected Against Details
5 Water Jets by a 6.3 mm
nozzle from any
direction
15 minutes at least
Water=12.5 LPM at 30
Kpa at a distance of 3 m
6 Powerful water jets
(12.5 mm nozzle) from
any direction
3 minutes at least
Water = 100 LPM at
100 Kpa at a distance of
3 m
7 Immersed up to 1 m 30 minutes at 1 m
8 Immersion beyond 1 m,
continuous immersion
Continues immersion in
water at 3 m
Hazardous Area Classification 19

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Hazardous Area Classification 20
Classification – NEC Standards
Defined by Class, Division and Groups
Class define the type of hazard;
 Unclassified
 Class I Flammable Gas or Vapor
 Class II Combustible dusts
 Class III Ignitable fibers or flyings

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Hazardous Area Classification 21
Divisions
 Division 1— Hazardous atmosphere is present during normal
operation.
 Division 2— Hazardous atmosphere is present only during
abnormal conditions such as equipment failure.

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Hazardous Area Classification 22
Groups Based on MESG & MIC
Group Material
A Methane, Propane, Petrol
B Arsine, Butadiene, ethylene oxide
C Ethylene, Acetylene, Hydrogen, Hydrogen
Sulfide
D Acetone, Ammonia, Benzene, Ethane, Toluene
E Metal Dust (Al, Mg, Ti, Zn, Cr, Cd)
F Coal Dust
G Grain Dust, cellulose acetate, skim milk, sugar
Explosive Fibers ( Cotton Lint, Flax, Rayon)

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Hazardous Area Classification 23
Auto ignition temperatures
Material
Temperature
(oC)
Acetaldehyde 175
Acetone 465
Acetylene 305
Gasoline 280
Hydrogen 500
Butane 420
Carbon 700
Coal (Cloud, Layer) 610, 180
Wheat (Cloud, Layer) 470, 260
Skim Milk 190, 200

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Hazardous Area Classification 24
Temperature Ratings
T Code Maximum Surface
Temperature
T1 450 °C
T2 300 °C
T2A 280 °C
T2B 260 °C
T2C 230 °C
T2D 215 °C
T3 200 °C
T3A 180 °C
T3B 165 °C
T3C 160 °C
T4 135 °C
T4A 120 °C
T5 100 °C
T6 85 °C

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Protection Concept
 Flame Path
 Non-Incendive components
 Oil immersed
 Encapsulation
Hazardous Area Classification 25

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Comparison
IEC
 Zone
 Zone 0, 1
 Zone 2
 Groups
 Group I
 Group IIA,IIB,IIC
 Group IIIA,IIIB, IIIC
 T Ratings
 T1, T2, T3, T4, T5,
T6
NEC
 Division
 Division 1
 Division 2
 Class
 Class I (Group
A,B,C,D,E,F,G)
 Class II
 Class III
 T Ratings
 T1, T2(A,B,C,D), T3(A,B,C), T4(A),
T5, T6
Hazardous Area Classification 36

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Comparison
IEC
 Protection Techniques
 Intrinsically safe
 Flameproof
 Increased safety
 Restricted breathing
 Encapsulation
 Purge/pressurized
protection
 Oil immersed
 Sand/powder filling
 Special protection
NEC
 Protection Techniques
 Flame path
Hazardous Area Classification 37

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Comparison
IEC
 IP Ratings
 10
 11
 54
 14
 55
 66
 66
 52
 67
 67
NEC
 NEMA Ratings
 1
 2
 3
 3R
 3S
 4
 4X
 5
 6
 6P
Hazardous Area Classification 38

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Comparison
IEC
 IP
 IP
 IP
 IP
 IP 52
 IP 52
 IP 54
NEC
 7
 8
 9
 10
 12
 12K
 13
Hazardous Area Classification 39

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Hazardous Area Classification 40
Lets Recap!
 Zones
 Gas groups
 Temperature Class
 Intrinsic Safety
 Divisions
 Ingress Protection

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Hazardous Area Classification 41
Exercise
II 2G Ex d IIC T6
II 1D Ex ia IIIB T5
Class I Div 2 B T2
Class III Div 1 E T1
IP 12
IP 35
IP 55

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Hazardous Area Classification 42
Thank You