WIKA R74.100 Mode D'emploi page 10

3. Special conditions for use (X conditions)
Hazardous dust atmosphere
For dusts, the procedure specified in ISO/IEC 80079-20-2 for
determining the ignition temperature has to be applied. The ignition
EN
temperature is determined separately for dust clouds and dust
layers, respectively. For dust layers, the ignition temperature depends
on the dust layer thickness per IEC/EN 60079-14.
Ignition temperature
of dust
Dust cloud T
Dust layer T
The permissible maximum medium temperature must not exceed the
lowest determined value, even in case of a malfunction.
Explosive atmosphere consisting of hybrid mixtures
The instruments must not be used in areas in which an atmosphere
consisting of explosive hybrid mixtures (dusts mixed with gases) can
occur.
3) Mount the instrument in such a way that, taking into consideration
the influence of convection and heat radiation, no deviation above or
below the permissible ambient and medium temperatures can occur.
4) The instruments must be earthed via the process connection. This
is why electrically conductive sealing should be used at the process
connection. Alternatively, take other measures for grounding.
External sources depend on end use application and must be
assessed by the end user.
5) Avoid handling of materials that react dangerously with the materials
used for the instrument, and substances liable to spontaneous
combustion.
10
Maximum permissible medium
temperature (in the measuring system)
< 2/3 T
cloud
< T
layer layer
layer thickness)
WIKA additional information models 73, 74 (ATEX)
cloud
− 75 K − (reduction depending on the