1. Hazardous Area Classification
1. Hazard & Its Causes/ Types
2. Hazardous Area Definitions
3. Material Classification
4. Area Classification
5. Prevention

2. 1. Hazard & Its Causes/ Types
Introduction: Any area in plant where manufacturing processes emit/ may emit gases, vapours or mists if mixed with air in correct proportions will produce explosive medium.
For an ignition to occur there must be:
A Hazard
A Source of Energy (Ignition or Hot Surface)
Air (To Support Combustion)

3. 1. Hazard & Its Causes/ Types
Fire Triangle:
Temperature
Air
Fuel

4. 1. Hazard & Its Causes/ Types
Terminology:
Flammable Mixture: Rich flammable fuel/ air combination in atmospheric conditions
Hazard: The Presence/ Risk of presence of flammable mixture
Hazardous Area: An area where during normal operations, a flammable mixture is likely to be present. The material involved is Crude oil & its derivatives, natural & synthetic process gases, Hydrocarbons, Metal dusts, fibers etc.

5. 1. Hazard & Its Causes/ Types
Non-Hazardous (Safe Area): An area, which is neither Hazardous nor remotely hazardous.
Electrical Apparatus For Hazardous Area: The apparatus which will not ignite the surrounding Hazardous Atmosphere, where it is used.
Types of Protection: Specific measures applied to electrical apparatus to prevent ignition in Hazardous Area.

6. 1. Hazard & Its Causes/ Types
Combustion
Polymers
Explosive
Corrosive
Ignition

7. 1. Hazard & Its Causes/ Types
Spontaneous Combustion: Many hazardous material have property known as auto ignition; Temperature at which ignition occurs without source of ignition.
Polymers:

8. 2. Definitions Prime Considerations:
Ease of Ignition: The type of Material is classified as per property of various materials for ease of ignition.
Area classification basis: Area over Hazard may extend.
Auto-Ignition Temperature: Temperature Class of Apparatus Used.

9. 3. Material Classification
Standards Followed:
Europe: CENELEC & IEC
North America: NEC
IEC : Gases and Vapours in two groups:
GR I : Mining (Sub-Surface) Industry
GR II : Surface Industry; Sub-Groups A,B,C.

10. 3. Material Classification
As per NEC:
Class 1: Gases & Vapours; further divided into 4 groups: A,B,C,D.
Class 2: Combustible Dusts; further divided into 3 groups based on their resistivity: G,E,F.
Class 3: Combustible fibers or flyings.

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