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 in accordance with the ATEX product guideline 94/9/EC. ATEX requires the type label of the sensor to include the ATEX marking, so usually this 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” after the approval number indicates that special conditions must 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 information on the possible areas of application and the type of protection used for the pressure sensor:
- 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)
- Use 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 may be installed in other zones, for example, 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 thus 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. IIC T1 for hydrogen