If pressure sensors, pressure transmitters along with other field equipment are employed near flammable gases or dust, they might be subject to marking relative to the ATEX product guideline 94/9/EC. ATEX requires the type label of the sensor to add the ATEX marking, so usually that 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 instance, an ?X? following the approval number indicates that special conditions must be observed when using the device. They are either given in the approval document and in the corresponding manual. Above all, marking in accordance with ATEX gives info on the possible areas of application and the sort of protection useful for the pressure sensor:
Explosion group:
I Mining industry, II other areas useful Device class:
Use in zone 0/20 near von flammable gases (1G), dust (1D)
Use in zone 1/21 near flammable gases (2G), dust (2D)
Use in zone 2/22 near flammable gases (3G), dust (3D)
However, there are also devices where only certain parts may be installed in other zones, for instance, a pressure sensor marked 1/2G may be installed in a tank with flammable content. The electronic the main transmitter is located on the outside 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, ideal for zone 2/22 m
encapsulation ideal for zone 1/21 and 2/22 Gas group and temperature class: i.e. Quadruple for hydrogen
Note:
Further information on the subject of hydrogen can be found on the WIKA website. Assuming you have any more questions, your contact will gladly help you.