e1453b
15
Fire & Security Products
Siemens Building Technologies Group
12.2001
2.2.2
Cable entry
Cables must be fed tightly through the rubber membrane in the base in order to prevent
condensation and air penetrating to the base/detector. Air «rinsing» arises due to differ-
ences in pressure in different rooms caused by air conditioning and ventilation systems.
Pressure compensation also arises through the cable conduit which to some extent
causes powerful air currents behind the base. This prevents smoke from properly enter-
ing the detector.
Smoke
Air current
Recess box
Fig. 12
Smoke is prevented from properly entering the detector if the rubber membrane
is not mounted air-tight.
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Fig. 13
Making the rubber membrane air-tight
Important:
Push the cable through the rubber membrane, or make holes with an awl. Do not cut
holes or slits!
