Special Hazards - WIKA 53 Mode D'emploi

2. Safety
A heat return flow from the process, which exceeds the ignition
temperature of the surrounding hazardous area, is not permitted and
must be prevented through appropriate thermal insulation!
GB
The following surface temperatures must not be exceeded:
Permissible
surface
temperature
1) If dust should settle on the instrument (up to a max. 5 mm layer thickness), a safety margin
of 75 K must be maintained between the minimum ignition temperature of the dust layer
and the surface temperature! For thicker dust layers a greater safety margin should be
incorporated!

2.4 Special hazards

8
Potentially explosive atmosphere
Gas/air/vapour/air/mist
≤ 80 % of the ignition
temperature in °C
WARNING!
Observe the information given in the applicable type
examination certificate and the relevant country-
specific regulations for installation and use in potentially
explosive atmospheres (e.g. IEC 60079-14, NEC, CEC).
Non-observance can result in serious injury and/or
damage to the equipment.
For additional important safety instructions for insturments
with ATEX approval see chapter "2.3 Additional safety
instructions for instruments with ATEX approval".
WARNING!
Residual media in dismounted instruments can result in
a risk to persons, the environment and equipment. Take
sufficient precautionary measures.
WIKA operating instructions models 53, 54, 55 (ATEX)
Dust / air
≤ 2/3 of the minimum
ignition temperature
in °C
1)