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 include the ATEX marking, so usually that 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 example, an ?X? following the approval number indicates that special conditions should be observed with all the device. Problem 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 used for the pressure sensor:
Explosion group:
I Mining industry, II other 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 near flammable gases (3G), dust (3D)
However, additionally, there are devices where only certain parts may be installed in other zones, for instance, a pressure sensor marked 1/2G could 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, 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 can be found on the WIKA website. For those who have any more questions, your contact will gladly assist you to.