Hazardous Area Classification & Protection

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Hazardous Area Classification &

Protection


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The Basic Physic PrinciplesAn explosion is the sudden chemical reaction of a flammable substance with oxygen with

the simultaneous release ofhigh energy. Flammable substances may be present in the

form ofgases,vapours, mists or dusts.

Explosion can only occur, when three factors come together :

1. Flammable material (in ignitable quantities)

2. Oxygen (in the air)

3. Ignition source


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Ignition source

Ignition of an explosive atmosphere can be caused by various sources:

> hot surfaces

> flames and hot gases

> mechanically generated sparks

> electrical installations> equalizing currents, cathodic corrosion protection

> static electricity

> lightning

> electromagnetic waves (high-frequency)

> optical radiation

> ionising radiation> ultrasonics

> adiabatic compression and shock waves

> exothermal reactions


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Flammable Material


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Classification


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Protection

The term primary explosionprotection refers to allprecautions, which prevent ahazardous explosive atmospherefrom being created can be

achieved by> avoiding flammable substances

(replacement technologies)

> inerting (addition of nitrogen,

carbon dioxide etc.)

> limitation of the concentration bymeans ofnatural or technicalventilation


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Hazardous locations are classified in

three ways by the National Electrical

Code: TYPE, CONDITION, and NATURE.


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Protection Methods

Pressurized Appartus


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Explosion Proof Exd


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Increased Safety Exi


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Intrinsically Safe Exn

Hazardous Area Classification & Protection

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