page 23 of 91 USB-QFLCII-14804/0
System categories
Only systems with approval for the corresponding zone may
be applied within
the system. Assignment to the categories can
be found in the following charts:
Category 1D 2D 3D
Safety measure Very high High Average
To be utilized in zone
(ATEX)
20 or 21 or 22 21 or 22 22
To be utilized in
Class II
Division 1 or 2 Division 1 or 2 Division 2
Maximum
surface
temperature
The maximum allowable surface temperature of the units should be
taken into consideration and should not be more than 2/3 of the
substance’s particular minimum ignition temperature of a dust cloud! In
addition, the maximum allowable surface temperature must not exceed
the minimum ignition temperature of a dust layer reduced by 80K.
3.8.4 Additional explosion protection measures to reduce the effects of
explosions
If ignition sources cannot entirely be avoided, additional explosion
protective measures are required.
This includes:
– spark detection and extinguishing equipment
– explosion pressure relief equipment
– explosion suppression equipment
The inlet isolation device is used as a mechanical explosion
protection measure for the purpose of isolating connected
ductworks from an explosion (used in addition to explosion
pressure relief or explosion suppression).
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