Poison leading ignition protection type is critical for the electrical connection of a pressure sensor with explosion protection. Hilarious does not necessarily need to be the one with the stricter requirements. This applies, for instance, for the UHP pressure transducers of the WU series from WIKA. They have been designed for used in semiconductor production.
Explosion protection can be an indispensable safety precaution there. Simply because the substances necessary for manufacturing include highly flammable gases. Consequently, there exists a risk of an explosive atmosphere forming.
Explosion protection concept
UHP pressure transducers for such processes should be made with the corresponding safety. Besides 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 more 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 does not affect the Ex idea 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 stands for 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 suitable mating connector).
?ec? is the leading ignition protection type
It is noticeable that the marking contains two ignition protection types. However, only one is pertinent for the electrical connection: the best ignition protection type. In the case of the pressure transducers from the WU series, this can be the Ex ec (Ex nA around 2022) mentioned first rather than the stricter Ex ic. This may also be observed in the connection values in the data sheet and operating instructions. Only the specification of the utmost supply voltage UN = 30 V, which is also stated in the IECEx certificate, is pertinent here.
What does the classification ?Ex ic? stand for? It only applies to the potentiometer of the transducer. The resistive component has an intrinsically safe circuit and can therefore be adjusted to improve zero drift during operation. In their overall form, the WU models usually do not require an intrinsically safe circuit. However, they must never be disconnected from the circuit during operation or when an Ex atmosphere exists.
Note
Rules on the WUC-1x and WU-2x UHP pressure transducers and about hydrogen are available on the WIKA website. When you have any questions, your contact will gladly help you.
Also read our articles
Ex protection: The most common ignition protection types for sensors in gas hazardous areas
Ex protection: The difference between the zone and division model