If pressure sensors, pressure transmitters and other field equipment are used near flammable gases or dust, they might be subject to marking in accordance with 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 the user. For example, an ?X? following the approval number indicates that special conditions should be observed when using the device. These 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 type 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)
Use in zone 1/21 near 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 instance, a pressure sensor marked 1/2G may be installed in a tank with flammable content. The electronic area 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 suitable for zone 1/21 and 2/22 Gas group and temperature class: i.e. Great for hydrogen
Note:
Further information about hydrogen are available on the WIKA website. For those who have any more questions, your contact will gladly help you.