Intrinsically safe how to safety of equipment can measures a very good presentation for explosive atmosphere

1. EXPLOSIVE ATMOSPHERES
EXPLOSIVE ATMOSPHERES
CLASSIFICATION AND
PROTECTION METHODS
MUHAMMAD KHIZAR HAYAT
MOHSIN MUMTAZ

2. EXPLOSIVE ATMOSPHERES
 EXPLOSIVE ATMOSPHERE
It is a mixture of:
1. Flammable substance (gas, vapor, mists, dusts)
2. Oxygen or Air
 HAZARDOUS AREA
An area in which an explosive atmosphere is present, or expected
to be present, such as to require special precautions for
construction, installation and use of electrical apparatus.

3. EXPLOSIVE ATMOSPHERES
IGNITION TRIANGLE
IGNITION ENERGY
FUEL
OXYGEN

4. EXPLOSIVE ATMOSPHERES
1. Explosion Containment:
 Explosion Proof Ex ‘’d’’
2. Segregation:
 Pressurization Ex ‘’p’’
 Encapsulation Ex ‘’m’’
 Oil Immersion Ex ‘’o’’
 Powder Filling Ex ‘’q’’
3. Prevention:
 Intrinsic Safety Ex ‘’i’’
 Increased Safety Ex ‘’e’’
 Simplified Ex ‘’n’’
METHODS OF PROTECTION

5. EXPLOSIVE ATMOSPHERES
 Sturdy mechanical construction
 Used for electrical apparatus where high power levels are required
 Not suitable for apparatus with relevant size
EXPLOSION CONTAINMENT

6. EXPLOSIVE ATMOSPHERES
Pressurization Encapsulation
For large electrical machines
For higher energy levels
Good mechanical protection
Not used for moving parts
SEGREGATION

7. EXPLOSIVE ATMOSPHERES
Origin Of Intrinsic Safety
England 1913: methane gas explosion in a coal mine
INTRINSIC SAFETY

8. EXPLOSIVE ATMOSPHERES
Categories Of Safety
Ex “ia” allows upto 2 independent faults
Ex “ib” allows only one fault
INTRINSIC SAFETY

9. EXPLOSIVE ATMOSPHERES
INTRINSICALLY SAFE BARRIERS
To interface electrical apparatus located in a hazardous location
with electrical apparatus located in a non hazardous location
TYPES:
 Diode Safety Barriers, Or “Passive” Barriers
 Galvanically Isolated Safety Barriers, Or “Active”
Barriers

10. EXPLOSIVE ATMOSPHERES
INTRINSICALLY SAFE BARRIERS
PASSIVE BARRIERS
 Lower component costs
 Introduction of errors by the limiting resistor and zener

11. EXPLOSIVE ATMOSPHERES
INTRINSICALLY SAFE BARRIERS
ACTIVE BARRIERS
• Better measurement accuracy
• Output signals can be directly used

12. EXPLOSIVE ATMOSPHERES
DEGREES OF PROTECTION OF ENCLOSURES
First Figure Indicates Protection
Against Solid Foreign Objects Index IP Index
Second Figure Indicates
Protection Against Water
Penetration
Non protected
Protected against solid object
50 mm  or more
Protected against solid object
12.5 mm  or more
Protected against solid object
2.5 mm  or more
Protected against solid object
1 mm  or more
Dust protected
Dust-tight
0
1
2
3
4
5
6
6 5
0
1
2
3
4
5
6
7
8
Non protected
Protected against vertically
Falling water drops
Protected against vertically Falling water
drops when enclosure tilted up to 15°
Protected against spaying water up to
60° from vertical
Protected against splashing water from
any direction
Protected against jets of water from any
direction
Protected against powerful jets of water
from any direction
Protected against immersion
Protected against continuous immersion
IP 65

13. EXPLOSIVE ATMOSPHERES
1. NORTH AMERICA
2. EUROPE
3. ATEX
CLASSIFICATION OF HAZARDOUS LOCATIONS

14. EXPLOSIVE ATMOSPHERES
Division 1 Dangers can be present during normal functioning
Division 2 Dangers can only be present in case of abnormal
functioning
Class I Gases or
Vapors
Group A Acetylene
Group B Hydrogen
Group C Ethylene
Group D Propane
Class II Dusts
Group E Metal Dust
Group F Coal Dust
Group G Grain Dust
Class III Fibers
NORTH AMERICA

15. EXPLOSIVE ATMOSPHERES
TEMPERATURE
CLASS
MAX SURFACE
TEMPREATURE
OC
GAS OR VAPOR
(EXAMPLE)
IGNITION
TEMPERATURE
OC
T1 450 Hydrogen 560
T2 300 Butane 365
T2 A 280
T2 B 260
T2 C 230
T2 D 215
T3 200 Heptane 215
T3 A 180
T3 B 165
T3 C 160
T4 135 Ethylether 170
T4 A 120
T5 100 Dehide Acetate 140
T6 85 Carbon Disulphide 102
SURFACE TEMPERATURE CLASS
NORTH AMERICA

16. EXPLOSIVE ATMOSPHERES
NORTH AMERICA
EXAMPLE
FISHER I/P CONVERTER
USA/Canada
NEMA 4
CL I, DIV 1, Group C,D
CL I, DIV 2, Group A,B,C,D
CL II, DIV 1,2 Group E,F,G

17. EXPLOSIVE ATMOSPHERES
Zone 0 An area in which an explosive air/gas mixture is
continuously present or present for long periods.
Zone 1 An area in which an explosive air/gas mixture is
likely to occur in normal operation.
Zone 2 An area in which an explosive air/gas mixture is
unlikely to occur; but, if it does, only for short
periods of time.
Group I Mines Methane
Coal Dust
Group II Surface
Industries
IIA Propane
IIB Ethylene
IIC Hydrogen
Acetylene
EUROPE

18. EXPLOSIVE ATMOSPHERES
Group I
( Mines )
( 150 °C ) Where coal dust can form a layer
( 450 °C ) for methane / air mixture, only if above risk is avoided by
sealing or ventilation
Temperature
Class
Max. Surface
Temperature
°C
Gas or Vapours
(Examples)
Ignition
Temperature
°C
T1 450 Hydrogen 560
T2 300 Butane 365
T3 200 Heptane 215
T4 135 Ethylether 170
T5 100 Dehide Acetate 140
Group II
( Surface )
T6 85 Carbon Disulphide 102
SURFACE TEMPERATURE CLASS
EUROPE

19. EXPLOSIVE ATMOSPHERES
EEx d II C T6
Equipment conform to
type of protection
standardised by CENELEC
( European standards )
Cl. Temperature, T1 - T6
Gas subdivision A, B, C
group
used in surface
Type of protection used
o, p, q, d, e, i, m, ...
MARKING
EUROPE

20. EXPLOSIVE ATMOSPHERES
NOTIFIED BODIES
( Official Journal of the EC No. C80/10 - March 17, 1994 )
ISSeP Institut scientifique de service publique Belgium
Demco Danmarks elektriske Materielkontrol Denmark
PTB Physikalisch Technische Bundesanstalt Germany
BVS Bergau-Versuchsstrecke "
LOM Laboratorio Oficial José Maria Madariaga Spain
INERIS Inst. Nat. de l'Environnement Industriel et des Risques France
LCIE Laboratoire Central des Industries Electriques "
CESI Centro Elettrotecnico Sperimentale Italiano Italy
KEMA NV KEMA Niederland
EECS Electrical Equipment Certification Service UK
.........

21. EXPLOSIVE ATMOSPHERES
ATEX
ATmosphere
EXplosibles

22. EXPLOSIVE ATMOSPHERES
DIRECTIVE ATEX 100 A NEW APPROACH
Group I
( mines )
82/130/EC
88/035/EC
91/269/EC
94/044/EC
Group II
( surface )
76/117/EC
79/196/EC
84/047/EC
88/571/EC
90/487/EC
94/026/EC
Directive
Machine
98/37/EC
( ESR 1.5.7 )
94/9/EC

23. EXPLOSIVE ATMOSPHERES
 Adopted by the European Union to
facilitate free trade
in EU.
 Covers equipment and protective systems,
which may be used in potentially explosive
atmospheres
 Covers both electrical and mechanical
equipment.
ATEX
Scope of the Directive

24. EXPLOSIVE ATMOSPHERES
DIRECTIVE ATEX 100A NEW APPROACH
94/9/EC
Dates of Application
• Transposition into national law 1 . 9 . 1995
• Application ( optional ) 1 . 3 . 1996
• Application ( total ) 1 . 7 . 2003

25. EXPLOSIVE ATMOSPHERES
PRE-REQUISITES OF THE DIRECTIVE
There are three pre-conditions for the directive to apply
 The equipment must have its own source of ignition
 Be intended for use in potentially explosive
atmospheres
 Be under normal atmospheric conditions

26. EXPLOSIVE ATMOSPHERES
ATEX
Zones Category Design of
Safety
Design
Requirement
G
Gas
D
Dust
Zone 0 Zone 20 1 Very high level
of safety
Safe with two
separate faults
Zone 1 Zone 21 2 High level of
safety
Safe with one
fault
Zone 2 Zone 22 3 Normal level of
safety
Safe in normal
operation
GROUP I Mines
GROUP II Equipment for surface installation

27. EXPLOSIVE ATMOSPHERES
EUROPEAN Marking Under New
Directive
...... II 2 G &/or D
Equipment Group ( surface )
Gas
Zone 1
Dust
Zone 21
Equipment Category ( surface )
Zone 1 for Gas / Zone 21 for Dust
Notified body code
EC logo
EC ’s
distinctive
Mark
for certified
Ex equipment

28. EXPLOSIVE ATMOSPHERES
Directive Implementation by ASCO
Explosion protection The no of the Identification The identification
Specific “Ex”. The EC type of protection no of Notified
equipment group examination Body involved in
and category of certificate Manufacturing
Equipment phase

29. EXPLOSIVE ATMOSPHERES
Comparison of Various standards
Area Classification
Continuous
Hazard
Intermittent
Hazard
Hazard Under
Abnormal
Condition
NORTH AMERICA
(CEC/NEC) DIVISION 1 DIVISION 2
EUROPE
(CENELEC/IEC) ZONE 0 ZONE 1 ZONE 2
ATEX DIRECTIVE ZONE 0 / 20 ZONE 1 / 21 ZONE 2 / 22

30. EXPLOSIVE ATMOSPHERES
EQUIVALENCE OF CLASSES AND GROUPS
HAZARD
CATEGORIES
APPARATUS CLASSIFICATION IGNITION
ENERGY
NORTH
AMERICA
EUROPE ATEX
METHANE Class I, Group D GROUP I
(Mines)
GROUP I
(Mines)
ACETYLENE
HYDROGEN
ETHYLENE
PROPANE
Class I, Group A
Class I, Group B
Class I, Group C
Class I, Group D
Group IIC
Group IIC
Group IIB
Group IIA
Group II
(Gas)
>20uJ
>20uJ
>60uJ
>180uJ
METAL DUST
COAL DUST
GRAIN DUST
Class II, GroupE
Class II, GroupF
Class II, GroupG
In
Preparation
Group II
(Dust)
More
Easily
Ignited
FIBERS Class III

31. EXPLOSIVE ATMOSPHERES
Types of Protection
General
Principles
European Practice Zone American practice Division
Explosion
containment
Explosion proof
Ex”d”
1,2 Explosion proof 2
Segregation
Pressurization Ex”p” 1,2 Purging 1,2
Encapsulation Ex”m” 1,2 Encapsulation 2
Oil Immersion Ex”o” 1,2 Oil immersion 1,2
Powder Filling Ex”q” 1,2 Not Recognized -
Prevention
Increased Safety
Ex”e”
1,2 Not Recognized -
Intrinsic Safety Ex”ia” 0,1,2 Intrinsic Safety 1,2
Intrinsic Safety Ex”ib” 1,2 Not Recognized -
Simplified Ex”n” 2 Non-Incendive 2

32. EXPLOSIVE ATMOSPHERES
TEMPERATURE COMPARISON
MAX SURFACE TEMP
OC
EUROPE/ ATEX NORTH AMERICA
450 T1 T1
300 T2 T2
280 T2 A
260 T2 B
230 T2 C
215 T2 D
200 T3 T3
180 T3 A
165 T3 B
160 T3 C
135 T4 T4
120 T4 A
100 T5 T5
85 T6 T6

33. EXPLOSIVE ATMOSPHERES
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