If pressure sensors, pressure transmitters along with other field equipment are employed in the vicinity of 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 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 should 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 information on the possible regions of application and the sort of protection useful for the pressure sensor:
Explosion group:
I Mining industry, II the 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 in the vicinity of 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 area of the 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 suitable 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. Should Wonderful have any more questions, your contact will gladly help you.