All installed process instruments in hazardous areas are required to have a type of protection that ensures safety of personnel as well as that of the instruments.
The following table provides the guidelines to select the type of protection according to the zone of risk:
|
Type of Protection |
Meaning |
|
Ex i |
Intrinsic
Safety |
|
Ex d |
Flameproof Enclosure |
|
Ex e |
Increased
Safety |
|
Ex m |
Encapsulation |
|
Ex p |
Pressurized
Apparatus |
|
Device |
Zone 0 |
Zone 1 |
Zone 2 |
|
Transmitter/Positioner |
Ex i |
Ex i (preferred) Ex d
(alternative) |
Ex i (preferred) Ex d, Ex e, Ex m (alternatives) |
|
Switch/Push-Button |
- |
Ex de |
Ex i (preferred) Ex e, Ex m (alternatives) |
|
Temperature Sensor |
- |
Ex e |
Ex e |
|
Solenoid Valve |
- |
Ex d |
Ex d |
|
Junction Box |
- |
Ex e |
Ex e |
|
Fire & Gas Detector |
- |
Ex d |
Ex d |
|
Analyzer |
- |
Ex I, Ex d |
Ex i, Ex d |
|
Local Panel |
- |
Ex d or Ex p |
Ex d or Ex p |
Note: As the Directive ATEX 94/9/EC is mandatory, only “Ex” equipment CE marked compliant with this ATEX Directive may be installed within the European Union.
Instruments will typically be designed to have immunity for radio frequency and electromagnetic interferences.
