If pressure sensors, pressure transmitters and other field equipment are used in the vicinity of flammable gases or dust, they may be subject to marking relative to the ATEX product guideline 94/9/EC. ATEX requires the sort 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 includes important information for the user. For instance, an ?X? following the approval number indicates that special conditions must be observed with all the device. Deadly are either given in the approval document and in the corresponding manual. Above all, marking according to ATEX gives information on the possible areas of application and the sort of protection used for the pressure sensor:
Explosion group:
I Mining industry, II other areas of use Device class:
Used in zone 0/20 in the vicinity of von flammable gases (1G), dust (1D)
Use in zone 1/21 in the vicinity of flammable gases (2G), dust (2D)
Use in zone 2/22 near flammable gases (3G), dust (3D)
However, additionally, there are devices where only certain parts could be installed in other zones, for example, 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 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, suitable 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 are available on the WIKA website. For those who have any more questions, your contact will gladly help you.