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ATEX Directive 94/9 EC Principal protection measures

Electrical Equipment


There are eight recognised concepts of explosion protection within Europe. These are detailed in the European EN 60079 series of Standards shown below

There are four basic methods utilised in order to avoid un-controlled ignitions and we recommend reviewing EN 1127 for further guidance available from BSI, cover page shown opposite


Exclusion of the flammable substance.
Prevention of component sparks or hot surfaces.
Explosion quenching.
Energy limitation.

By applying individually or in combination, the following protection concepts are applied to equipment in order to achieve this

EX Protection Concepts

Zone(s)

ATEX Category

Methodology

Intrinsic Safety

ia

0,1,2

1

Limited energy - will not cause ignition in normal operation, with one fault and with any combination of two faults applied

ib

1,2

2

Limited energy - will not cause ignition in normal operation, with one single fault applied

ic

2

3

Limited energy - will not cause ignition in normal operation

Flameproof

d

1,2

2

Explosion containment, will not allow transmission of an internal explosion to the surrounding environment

Increased Safety

e

1,2

2

Prevention of arcs, sparks and hot surfaces in normal operation

Purged & Pressurisation

p

1,2

2

Excludes the hazardous atmospheres by 50Pa positive pressure of inert gas

Powder Filled

q

1,2

2

High power electronics, such as solenoids, capacitors etc. prevents the explosive atmosphere reaching a hazard

Encapsulation

m

1,2

2

Light current applications and instrumentation

Oil Immersion

o

1,2

2

High current switchgear, transformers etc. prevents the explosive atmosphere reaching a hazard

Non-Sparking

n

2

3

Is not capable of causing an ignition and faults are unlikely to occur


 
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