If pressure sensors, pressure transmitters and other field equipment are employed 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 sort label of the sensor to add the ATEX marking, so usually this is labelled directly onto the sensor during production.
Close to Attack and the approval number, the marking of pressure sensors also contains important information for an individual. For example, an ?X? following the approval number indicates that special conditions should 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 home elevators the possible areas of application and the sort of protection useful for the pressure sensor:
Explosion group:
I Mining industry, II the areas useful 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 example, a pressure sensor marked 1/2G could be installed in a tank with flammable content. The electronic part of the transmitter is located externally 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, 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. IIC T1 for hydrogen
Note:
Further information about hydrogen can be found on the WIKA website. When you have any further questions, your contact will gladly help you.