If pressure sensors, pressure transmitters along with other field equipment are used 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 include the ATEX marking, so usually that 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. 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 type of protection used for the pressure sensor:
Explosion group:
I Mining industry, II other 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 near flammable gases (3G), dust (3D)
However, there are also devices where only certain parts could be installed in other zones, for example, a pressure sensor marked 1/2G may be installed in a tank with flammable content. Danger of the transmitter is located on the outside of the tank, and therefore 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, suitable 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 on the subject of hydrogen are available on the WIKA website. When you have any more questions, your contact will gladly assist you to.g