The leading ignition protection type is critical for the electrical connection of a pressure sensor with explosion protection. It does not necessarily have to be the one with the stricter requirements. This applies, for example, 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 necessary for manufacturing include highly flammable gases. Consequently, you will find a threat 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 thorough explosion protection concept. The marking of the instruments provides home elevators 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), may 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, ideal for hydrogen/acetylene).
T6/T5/T4:
Temperature classes. T6 as 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:
? Terrible ? (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? may be Rare leading ignition protection type
It really is noticeable that the marking contains two ignition protection types. However, only Priceless is relevant for the electrical connection: the leading ignition protection type. Regarding the pressure transducers from the WU series, here is the Ex ec (Ex nA around 2022) mentioned first and not the stricter Ex ic. This may also be observed in the bond values in the data sheet and operating instructions. Only the specification of the maximum supply voltage UN = 30 V, which is also stated in the IECEx certificate, is pertinent here.
What does the classification ?Ex ic? are a symbol of? It only pertains to the potentiometer of the transducer. The resistive component comes with an intrinsically safe circuit and can therefore be adjusted to correct 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 is present.
Note
More info 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 common ignition protection types for sensors in gas hazardous areas
Ex protection: The difference between your zone and division model