If pressure sensors, pressure transmitters and other field equipment are used in the vicinity of flammable gases or dust, they might be subject to marking relative to the ATEX product guideline 94/9/EC. ไดอะแฟรม requires the sort label of the sensor to include the ATEX marking, so usually this is labelled directly onto the sensor during production.
Close to the Notified Body and the approval number, the marking of pressure sensors also contains important information for the user. For example, an ?X? after the approval number indicates that special conditions must be observed with all the device. They are either given in the approval document and in the corresponding manual. Most importantly, marking in accordance with ATEX gives information on the possible regions of application and the sort of protection used for the pressure sensor:
Explosion group:
I Mining industry, II other areas of use Device class:
Use in zone 0/20 near von flammable gases (1G), dust (1D)
Used in zone 1/21 near flammable gases (2G), dust (2D)
Used in zone 2/22 near flammable gases (3G), dust (3D)
However, there are also devices where only certain parts could be installed in other zones, for instance, a pressure sensor marked 1/2G could be installed in a tank with flammable content. The electronic portion of the transmitter is located externally of the tank, and thus in zone 1.
Examples for forms of protection:
i intrinsic safety (Limitation of electrical ignition energy by limiting current and voltage)
ia for Zone 0 or Zone 20 (for Zone 20 also iaD)
ib for Zone 1 or Zone 21 (for Zone 21 also ibD)
ic for Zone 2 d
flameproof / explosion proof enclosure, ideal for zone 1/21 and 2/22 n
non-incendive, suitable for zone 2/22 m
encapsulation ideal for zone 1/21 and 2/22 Gas group and temperature class: i.e. IIC T1 for hydrogen
Note:
Further information about hydrogen are available on the WIKA website. For those who have any further questions, your contact will gladly assist you to.