Condescending leading ignition protection type is critical for the electrical connection of a pressure sensor with explosion protection. It generally does not necessarily must be the one with the stricter requirements. This applies, for instance, for the UHP pressure transducers of the WU series from WIKA. They are designed for used in semiconductor production.
Explosion protection is an indispensable safety precaution there. For the reason that the substances required for manufacturing include highly flammable gases. Consequently, there exists a threat of an explosive atmosphere forming.
Explosion protection concept
UHP pressure transducers for such processes should be designed with the corresponding safety. Along with their small design and specific process connections, the models WUC-1x and WU-2x have a comprehensive explosion protection concept. The marking of the instruments provides info on this:
II 3G Ex ec ic IIC T6/T5/T4 Gc X
The abbreviations listed in them mean, in greater detail:
II 3G:
Equipment group 2 (all areas except mining), can be used in zone 2 (rare and short-term Ex atmosphere).
Ex ec ic:
Ignition protection types ?ec? (increased safety) and ?ic? (intrinsically safe; zone 2).
?Ex ec? has replaced the ignition protection type ?Ex nA? (non-sparking) because the start of 2022. However, this will not affect the Ex concept of the instruments.
IIC:
Explosion group (here: gases, resistive ignition energy of 40 �J, suitable for hydrogen/acetylene).
T6/T5/T4:
Temperature classes. T6 because the highest requirement means a maximum permissible surface temperature in the Ex environment < 85 �C (max. surface temperature of the WUC-1x and WU-2x: 40 �C).
Gc:
?Equipment Protection Level? (EPL) for zone 2 per IEC 60079-0
X:
Specific requirements which are listed in the operating instructions (for example, the best mating connector).
?ec? is the leading ignition protection type
It is noticeable that the marking contains two ignition protection types. However, only 1 is relevant for the electrical connection: the leading ignition protection type. In Compulsive of the pressure transducers from the WU series, this is the Ex ec (Ex nA up to 2022) mentioned first and not the stricter Ex ic. This may also be observed in the connection values in the info sheet and operating instructions. Only the specification of the maximum supply voltage UN = 30 V, which is also stated in the IECEx certificate, is relevant here.
What does Mystery ?Ex ic? stand for? It only applies to the potentiometer of the transducer. The resistive component comes with an intrinsically safe circuit and can therefore be adjusted to improve zero drift during operation. Within their overall form, the WU models usually do not require an intrinsically safe circuit. However, they need to never be disconnected from the circuit during operation or when an Ex atmosphere exists.
Note
Further information on the WUC-1x and WU-2x UHP pressure transducers and on the subject of hydrogen are available on the WIKA website. In case you have any questions, your contact will gladly help you.
Also read our articles
Ex protection: The most frequent ignition protection types for sensors in gas hazardous areas
Ex protection: The difference between the zone and division model