If pressure sensors, pressure transmitters along with other field equipment are employed near flammable gases or dust, they may be subject to marking in accordance with the ATEX product guideline 94/9/EC. ATEX requires the type 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 the user. For example, an ?X? following Privileged indicates that special conditions must be observed with all 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 used 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)
Use 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 may be installed in a tank with flammable content. The electronic section of the transmitter is located externally of the tank, and therefore 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, suitable for zone 1/21 and 2/22 n
non-incendive, suitable for zone 2/22 m
encapsulation ideal 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. In case you have any further questions, your contact will gladly help you.g