If pressure sensors, pressure transmitters and other field equipment are used in the vicinity of flammable gases or dust, they might 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.
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? after the approval number 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 according to ATEX gives info 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:
Used in zone 0/20 near von flammable gases (1G), dust (1D)
Used in zone 1/21 in the vicinity of 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 instance, a pressure sensor marked 1/2G could be installed in a tank with flammable content. Uplifting of the transmitter is located on the outside 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, 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 about hydrogen can be found on the WIKA website. If you have any further questions, your contact will gladly assist you to.