e1276e
21
Siemens Building T
echnologies
Cerberus Division
09.2000
4.6
Monitoring areas with joist constructions
Note that the term «joists» also covers such structures as air conditioning ducts which are
mounted up to 0.15m below the ceiling.
In principle linear smoke detectors must be placed in the inter-joist area. Due to economic
reasons this is not possible, layout underneath joist constructions is also permissible ac-
cording to 4.6.1
4.6.1
Layout underneath joist construction
The linear smoke detector can be mounted below the joists, if:
the joist height is less than 2O% of the total height of the room
If the width of the inter-joist area is
50% of the maximum broad of surveillance
or if the inter-joist area is
200m
2
When calculating the width of the monitored area that only the distance up to the joist
construction counts as the height of the room h.
h: Height for determining max. width of monitored area
100%
h
<
20%
min. 30cm
Fig. 15 Detector layout underneath joist construction
4.6.2
Layout within the joist area
When the joist construction is more than 2O% of the total height of the room, than the
joists must be considered as room dividers and each section must be individually moni-
tored.
100%
> 20%
When distance exceeds max. monitored area
mount more than one DLO11.. per section
Min. gap between two parallel
beams determined by distance
Fig. 16 Detector layout within joist construction
