B2Q

Assume an atrium has a headroom of 25m. As a performance-based fire safety design, beam detectors will be provided at level 14.0m and 24.5m to act as the smoke detection system for the atrium. To minimize the possible false alarm, cross zoned detection is applied to the beam detectors, that is, two beam detectors will be provided in the same detection zone. Due to the excessive ceiling height, long-throw sprinkler system actuated by infra-red flame detectors is installed at level 3.0m to provide adequate water coverage to the atrium base as the fire suppression system for the atrium. Cross zoned detection is also applied to the infra-red flame detectors, that is, two infra-red flame detectors will be provided in the same detection zone. Therefore, the fire protection system for the atrium include:

Beam detectors Two at level 14.0m

Two at level 24.5m

Infra-red flame detectors Two at level 3.0m

Long-throw sprinkler system One set (One pump in duty, One pump in standby and One control valve)

Basic Event Probability

Beam detector fails to send fire signal to the fire safety control panel in case of fire 0.01

Infra-red flame detector fails to send fire signal to the fire safety control panel in case of fire 0.015

The fire safety control panel will not deliver a signal to actuate the pumps and valve 0.01

Pump fails to start upon receipt of the actuation signal 0.005

Valve fails to open upon receipt of the actuation signal 0.001

No water in the sprinkler tank 0.0001

a) Use fault tree or event tree to illustrate the failure of the fire protection system serving for the atrium;

b) Given the probability of the following events, evaluate the failure probability of the fire protection system serving for the atrium.

B.2 Assume an atrium has a headroom of 25m. As a performance-based re safety design, 13) beam detectors will be provided at level 140m and 24.5m to act as the smoke detection system for the atrium. To minimize the possible false alarm, cross zoned detection is applied to the beam detectors, that is, two beam detectors will be provided in the same detection zone. Due to the excessive ceiling height, long-throw sprinkler system actuated by infra-red ame detectors is installed at level 3.0m to provide adequate water coverage to the atrium base as the re suppression system for the atrium. Cross zoned detection is also applied to the infra-red ame detectors, that is, two infra-red ame detectors will be provided in the same detection zone. Therefore, the re protection system for the atrium include: Beam detectors Two at level 14.0m Two at level 245m Infra-red ame detectors Two at level 3.0m Long-throw sprinkler system One set (One pump in duty, One pump in standby and One control valve) Use fault tree or event tree to illustrate the failure of the re protection system serving for the atrium; Given the probability of the following events, evaluate the failure probability of the re protection system serving for the atrium. Beam detector fails to send re signal to the re safety control 0 01 panel in case of re ' Infra-red ame detector fails to send re signal to the re safety 0 015 control panel in case of re ' The re safety control panel will not deliver a signal to actuate the 0 01 pumps and valve ' Pump fails to start upon receipt of the actuation signal 0.005 Valve fails to open upon receipt of the actuation signal 0.001 No water in the sprinkler tank 0.0001