Explosion Research Ltd.
Zone
System nomenclature
These represent the more common techniques of protection
|
Group / Environment
|
Explosion Risk |
MPL (Minimum Protection Level) |
Zone |
Ex code
|
Minimum protection technique |
Base Standard used |
|
I (mines) |
Energized |
Ma |
|
|
|
|
|
I (mines) |
Not Energized |
Mb |
|
|
|
|
|
II (gas) |
Explosive gas > 1000 hrs/yr |
Ga |
0 |
Ex ia Ex ma |
Intrinsic safety encapsulation |
60079-11 60079-18 |
|
II (gas) |
Explosive gas 10 to 1000 hrs/yr |
Gb |
1 |
Ex ib Ex mb Ex pxb Ex eb Ex db Ex s |
Intrinsic safety Encapsulation Pressurized Increased safety Explosion Proof special |
60079-11 60079-18 60079-2 60079-7 60079-1 Two certifiers consensus |
|
II (gas) |
Explosive gas 1 to 10 hrs/yr |
Gc |
2 |
Ex ec Ex ic Ex pzc Ex pyc Ex nC Ex nR |
Non-arcing Limited energy Pressurized Pressurized Sealed Restricted breathing |
60079-7 60079-11 60079-2 60079-2 60079-15 60079-15 |
|
III (dust) |
Explosive Dust 1 > 1000 hrs/yr |
Da |
20 |
|
|
|
|
III (dust) |
Explosive Dust 10 to 10000 hrs/yr |
Db |
21 |
|
|
|
|
III (dust) |
Explosive Dust 1 to 10 hrs/yr |
Dc |
22 |
|
|
|