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

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)

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

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.

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.

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

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:

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.

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.

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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