Bosch FAS-420-TM - Page 14

14 en | Technical Specifications FAS-420-TM Aspirating Smoke Detector
F.01U.088.878 | 4.1 | 2010.11 Operation Guide Bosch Sicherheitssysteme GmbH
– Phase 2
As soon as the system has switched to alarm state as a result of a rise in the
concentration of smoke particles typical of a fire, the alarm is signaled.
Figure 2.6 Phase 2: Early fire detection
– Phase 3
When the alarm is signaled, once the configurable pre-alarm threshold is reached, the
aspiration fan switches off and a second fan blows all smoke particles out of the pipe
system in the opposite direction.
Figure 2.7 Phase 3: Blowing out
– Phase 4
Once the pipe system has been blown out, the direction of flow is reversed again and the
time required for the smoke particles to penetrate into the detector module is measured.
On the basis of this time, the location of the smoke source can be accurately traced to
one of the monitored areas.
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FAS-420-TM series