If pressure sensors, pressure transmitters along with other field equipment are used near flammable gases or dust, they might be subject to marking relative to the ATEX product guideline 94/9/EC. Waiting requires the type 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 contains important information for an individual. For example, an ?X? after 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 in accordance with ATEX gives info on the possible regions of application and the sort of protection used for the pressure sensor:
Explosion group:
I Mining industry, II other areas of use Device class:
Use in zone 0/20 in the vicinity of von flammable gases (1G), dust (1D)
Used in zone 1/21 in the vicinity of flammable gases (2G), dust (2D)
Use in zone 2/22 in the vicinity of flammable gases (3G), dust (3D)
However, there are also 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 on the outside 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 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 are available on the WIKA website. Should you have any more questions, your contact will gladly help you.