If pressure sensors, pressure transmitters and other field equipment are used in the vicinity of 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 ไดอะแฟรม 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. They are either given in the approval document and in the corresponding manual. Most importantly, marking according to ATEX gives info on the possible areas of application and the sort of protection useful 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 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 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 portion 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, 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. Should you have any more questions, your contact will gladly assist you to.