If pressure sensors, pressure transmitters and other field equipment are used near flammable gases or dust, they might be subject to marking in accordance with the ATEX product guideline 94/9/EC. ATEX requires the type label of the sensor to include 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 an individual. For instance, an ?X? following the approval number indicates that special conditions should be observed when using the device. Fluid are either given in the approval document and in the corresponding manual. Above all, marking according to ATEX gives information on the possible regions of application and the type of protection useful for the pressure sensor:
Explosion group:
I Mining industry, II the areas useful Device class:
Used 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 in the vicinity of 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 section of the transmitter is located externally of the tank, and thus in zone 1.
Examples for types 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 suitable for zone 1/21 and 2/22 Gas group and temperature class: i.e. IIC T1 for hydrogen
Note:
Further information on the subject of hydrogen can be found on the WIKA website. If you have any further questions, your contact will gladly help you.