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 type label of the sensor to add 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? following Increase 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 regions of application and the sort of protection useful for the pressure sensor:
Explosion group:
I Mining industry, II the areas useful Device class:
Use in zone 0/20 near von flammable gases (1G), dust (1D)
Use in zone 1/21 in the vicinity of flammable gases (2G), dust (2D)
Used in zone 2/22 in the vicinity of 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 may be installed in a tank with flammable content. The electronic part of the transmitter is located on the outside 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, 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. Should you have any further questions, your contact will gladly help you.