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 sort label of the sensor to add the ATEX marking, so usually this is labelled directly onto the sensor during production.
Next to the Notified Body and the approval number, the marking of pressure sensors also includes important information for an individual. For instance, an ?X? after the approval number indicates that special conditions should be observed when using the device. These are either given in the approval document and in the corresponding manual. Most importantly, 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 of use Device class:
Use 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 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, ideal for zone 2/22 m
encapsulation suitable for zone 1/21 and 2/22 Gas group and temperature class: i.e. Save for hydrogen
Note:
Further information on the subject of hydrogen are available on the WIKA website. In case you have any further questions, your contact will gladly help you.g