The leading ignition protection type is crucial for the electrical connection of a pressure sensor with explosion protection. pressure gauge does not necessarily need to be the main 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 use 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, there is a threat of an explosive atmosphere forming.
Explosion protection concept
UHP pressure transducers for such processes should be made with the corresponding safety. Along with 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 inside them mean, in greater detail:
Equipment group 2 (all areas except mining), can be utilized 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 concept of the instruments.
Explosion group (here: gases, resistive ignition energy of 40 ï¿½J, ideal for hydrogen/acetylene).
Temperature classes. T6 because the highest requirement stands for a maximum permissible surface temperature in the Ex environment < 85 ï¿½C (max. surface temperature of the WUC-1x and WU-2x: 40 ï¿½C).
?Equipment Protection Level? (EPL) for zone 2 per IEC 60079-0
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 one is relevant for the electrical connection: the best ignition protection type. In the case of the pressure transducers from the WU series, this is actually the Ex ec (Ex nA around 2022) mentioned first rather than the stricter Ex ic. This can also be seen in the bond values in the info 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 comes with an intrinsically safe circuit and may therefore be adjusted to correct 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.
Further information on the WUC-1x and WU-2x UHP pressure transducers and on the subject of hydrogen are available on the WIKA website. Assuming you have any questions, your contact will gladly assist you to.
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