1. Selection of Explosion Protected Equipment for Hazardous Locations
Pieter Coetzee
Explosion Prevention Consultant
South African Flameproof Association
MIE workshop 2015

2. Contents Introduction Standards
Occupational Health and Safety Act. (Act 85 of 1993) & ARP 0108
Area Classification
Marking of Ex equipment
Equipment protection levels (EPL)
Gas Groups
Temperature Classification
Selection of Explosion Protected Equipment
Conclusion

3. Introduction Hazardous Location Definition Explosion protected
An area in which an explosive gas atmosphere or combustible dust, in the form of a cloud is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment
Explosion protected
descriptive of apparatus designed and approved for use in hazardous locations in accordance with a suitable protection method, including Ex d, Ex i, Ex e, Ex p, Ex nA, Ex m and Ex q

4. Standards
IEC/SANS IEC/SANS IEC/SANS

5. Three components are required for an explosion or fire to occur
Oxygen
Flammable Substance
Ignition Source

6. Ignition Source

7. Possible results from explosions, incidents and fires
Includes:
loss of life
loss of production (Financial Impact)
damage to plants
Environmental impact
Explosion in Reynosa Mexico, Unofficially a leak of gas.
14Killed
Many Hospitalized
February 7, 2008
Sugar Involved
Reynosa Mexico reported the death of 30 contractors/PEMEX workers and 42 injured

8. Loss of life

9. Acts and regulations
Act – The Act shall refer to the latest issue of the Act
Industry: Mines
- Mines Health and Safety Act (Act 29 of 1996)
Industry: Surface
Occupational Health and Safety Act (Act 85 of 1993)
To meet safety requirements as per section 44 of the OHS Act.

10. Electrical Machinery Regulation (EMR)
Every employer or user shall identify all hazardous locations and classify them
EMR 9(2)
The equipment must be appropriate to the area classification
EMR 9(3)
The end user shall be in possession of a certificate in a form acceptable to the chief inspector - IA certificates as per ARP 0108 etc.

11. STEP 1 EMR 9(1)Area Classification /Map
Area classification is:
is a method of analysing and classifying the explosive environment,
takes into account gas groups and temperature classes.
is to facilitate proper selection and installation of apparatus to be used safely in that environment,
The basic underlying philosophy is SAFETY of life and property by quantifying the location.

12. Objectives of Area Classifications
An approximate structure of the procedure is outlined in the following block diagram

13. EMR 9(1)Area Classification /Map
Important information
Area divided into Zones

14. Important information on Area Classification drawing/Map
Zones/EPL (0/Ga; 1/Gb; 2/Gc for gas or 20/Da; 21Db;
22/Dc for dust)
Material name (flammable substance)
Flash point
Ignition temperature
Gas group (IIA; IIB; IIC)
Temperature class for flammable substance( T1- T6)
Extend of the zones ( vertical and horizontal in meters)

15. Equipment Protection Level (EPL)
The level of protection assigned to equipment based on:
its risk of becoming a source of ignition, and
distinguishing the differences between
explosive gas atmospheres,
explosive dust atmospheres
The higher the risk like zone 0, a higher level of protection is required like Ex ia; ma.
The lower the risk like Zone 2, a lower level of protection is required like Ex ic, p .
EPL-Scale

16. Equipment Protection Level (EPL)
Group
Ex risk
Risk
Zone
EPL
Minimum type of protection
I (mines)
energized
Very high
“0” Ma
Same as Ga
de-energized in presence of Ex atmosphere
High 1 Mb
Same as Gb
II (gas)
explosive atmosphere > 1000 hrs/yr Ga
ia, ma
explosive atmosphere between 10 and 1000 hrs/yr Gb
ib, mb, px, py, e, o, q, d
explosive atmosphere between 1 and 10 hrs/yr
Low 2 Gc
nA, ic, pz
III (dust)
explosive surface > 1000 hrs/yr 20 Da
ta; ia; ma
explosive surface between 10 and 1000 hrs/yr 21 Db
tb, ib, mb, p
explosive surface between 10 and 10 hrs/yr 22 Dc
tc, ic, p

17. Safety Height and Hazard Depth

18. Typical example and interpretation of an Ex marking
E Ex ia IIC T6 Ga
Temperature Classification (T-Class) identifies the maximum ignition- capable surface temperature which the equipment will exhibit.(T6 =85°C)
Unless otherwise stated, the maximum ambient temperature to which the equipment may be subjected (and thus the maximum ambient temperature for which the T-Class will be true) is 40°C
Gas Group/ Apparatus Group
The roman II indicates surface industry (not mining). IIC is the most onerous subgroup in Group II.
Equipment which is suitable for IIC will also be suitable for IIA and IIB
Code letters indicate the type of protection (or types) of protection utilized by this equipment:‘ia’ indicates Intrinsic Safety
Ex: is the symbol for explosion protection
The initial ‘E’ indicating conformity with European EN standards.
This ‘E’ is no longer used so it will not be shown on equipment which has been designed and certified since around 2007
Equipment protection level

19. STEP 2 Gas Groups - Ex d IIC T4 Gb
Industry
Gas Group
Substance
MIE
Selection of equipment
Mining Industry
Group I I
Methane
200µJ
Equipment only suitable for mines unless it is additional approved for surface: Marked I/IIC
Surface Industry
Group II
IIA
Propane
180 µJ and higher
IIA; IIB and IIC certified equipment may be use in an IIA area.
IIB
Ethylene
60 µJ -180 µJ
IIB and IIC certified equipment may be used in an IIB area.
IIC
Hydrogen
20 µJ – 60 µJ
Only IIC certified equipment is allowed to be used in an IIC area.
According to SANS , 2009, equipment group for dust is to be group III - IIIA, IIIB or IIIC for electrical equipment for places with an explosive dust atmosphere.
(The gases noted in the table are typical gases for each group.)
MIE – Minimum ignition energy
Gas Group IIC is the most severe gas group

20. Verification of gas groups:
NOTE: The above shows clear reference of II and IIC together.

21. The equipment requirements increase from II A to II C
Increase in the level of protection will increase the cost !

22. STEP 3 Temperature Classes - Ex d IIC T4 Gb
Explosion proof equipment, installed within the Ex area, is divided into 6 temperature classes (T1 to T6).
Temperature class is not – as it is often wrongly believed – the operating temperature range of the equipment, but the maximum permissible surface temperature of the equipment, in relation to + 40°C ambient temperature on any surface area, and should not be exceeded at any time.
The maximum surface temperature must remain below the ignition temperature of the all flammable substances at all times.
The equipment requirements rise from T1 to T6.
T-Class
Maximum surface temperature
of the equipment
Ignition temperatures of combustible substances T1
450°C
> 450 °C T2
300°C
> 300 °C T3
200°C
> 200 °C T4
135°C
> 135 °C T5
100°C
> 100 °C T6
85°C
> 85 °C

23. Modification of Ex e enclosures
Special terminals

24. Ex e Special terminals

25. HAC Temperature Classes – Zone 2 IIC T1
All flammable gases and vapours are placed in a gas group and a temperature class as per table.

26. STEP 4 EMR9(2) Selection of Explosion Protected Equipment (EPE)
Selection of EPE will always follow the area classification
Type of protection must be suitable for the Zone/EPL of use.
EPE must be covered by an approved Inspection Authority (IA) certificate issued by an ATL.
Ingress protection (IP) Ratings – application.
Ambient temperature rating –20°C to +40°C if not on certification.

27. Different Ex Techniques
Protection Type
Symbol
Application
Typical application
Principle
Energy Limiting
Intrinsic Safety
Ex ia
Ex ib
Ex ic
Ex iaD
Zone o
Zone 1
Zone 2
Zone 20
Instrumentation; control gear
Containment
Flameproof
Ex d
Zone 1 & 2
Switchgear; motors; pumps
Refined Mechanical design
Increase Safety
Ex e
Motors; Light fittings
Non-sparking
Ex nA (ec)
Segregation
(Isolation)
Pressurization
Exp;
Ex pD
Zone 1& 2
Zone 21
Motors; analysers;
control rooms
Encapsulation
Ex ma
Ex m;
Ex mD
Zone 0
Solenoids; fuses; relays
Sand filling
Ex q
Strip heaters,
capacitors

28. EMR9(2) Selection of Explosion Protected Equipment (EPE)
EPE for use in different zones
EPL’s
Hazardous area divided into zones and EPE allowed in these zones 1 2
Zone 0 EPE - Ex ia; ma Ga 
Zone 1 EPE - Ex ib; d; e; m; p; q Gb 
Zone 2 EPE - Ex ic; nA; nR; nC; Gc

29. Verification of EPE for hazardous locations
Hazardous Area Classification
Zone 1; Gas Group IIB; Temp: T4
Equipment marking
Ex d IIC T5 Gb - 20 to 40°C
Verification sheet
Area
Equipment
Compliance
Zone 1
d (Gb)
Suitable
Gas Group
IIB
IIC
Temperature class T4 T5
Ambient temperature
- 20 to 40°C

30. Hazardous Location Information
Practical Exercise: Equipment selection and verification for hazardous locations
Equipment (EPE)
Hazardous Location Information
Yes/No
Classification
Chemical
Gas Group
Temp. Class
Example:
Ex nA IIB T2
Zone 1 N
Illuminating Paraffin
IIA Y T3
Comments: EPE protection type (nA) not applicable to the Classification Zone 1. Equipment (EPE) temperature class too high for the location temperature class.
Ex o IIB T2
Carbon Disulphide
IIC T6
Ex m IIB T4
Zone 2
Ethyl Nitrite
Ex ib II T4
Zone 0
Ethylene Oxide
IIB T2
Ex n IIB T2
Acetylene
Ex ib IIB T6
Octane
Comments: Y N Y N N N N N Y Y

31. Hazardous Location Information
Practical Exercise: Memorandum
Equipment (EPE)
Hazardous Location Information
Yes/No
Classification
Chemical
Gas Group
Temp. Class
Example:
Ex nA IIB T2
Zone 1 N
Illuminating Paraffin
IIA Y T3
Comments: EPE protection type (nA) not applicable to the Classification Zone 1. Equipment (EPE) temperature class too high for the location temperature class.
Ex o IIB T2
Carbon Disulphide
IIC T6
Comments: Gas group incorrect; temperature class too high.
Ex m IIB T4
Zone 2
Ethyl Nitrite
Comments: Temperature class too high.
Ex ib II T4
Zone 0
Ethylene Oxide
IIB T2
Comments: Protection type can only be used in Zones 1 and 2.
Ex n IIB T2
Acetylene
Comments: Protection type incorrect; Gas Group incorrect.
Ex ib IIB T6
Octane
Comments:

32. People are our most valuable asset and the industry must ensure a safe work environment as per Section 8 and Electrical Machinery regulation 9 as per the latest issue of the Occupational Health and Safety Act and Regulations (85 0f 1993).