If pressure sensors, pressure transmitters along with other field equipment are employed near flammable gases or dust, they may be subject to marking relative to 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 contains important information for the user. For instance, an ?X? after the approval number indicates that special conditions must be observed with all the device. Uninterested are either given in the approval document and in the corresponding manual. Above all, marking in accordance with ATEX gives home elevators the possible regions of application and the sort of protection useful for the pressure sensor:
Explosion group:
I Mining industry, II the areas useful Device class:
Used in zone 0/20 in the vicinity of von flammable gases (1G), dust (1D)
Used in zone 1/21 near flammable gases (2G), dust (2D)
Use in zone 2/22 near flammable gases (3G), dust (3D)
However, there are also devices where only certain parts may be installed in other zones, for example, a pressure sensor marked 1/2G could be installed in a tank with flammable content. The electronic part 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 ideal 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. Should you have any further questions, your contact will gladly help you.