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 |