Reliability of automatic sprinkler systems in shopping centres in Hong Kong

Pao Yue-kong Library Electronic Theses Database

Reliability of automatic sprinkler systems in shopping centres in Hong Kong

 

Author: Tang, Wai-kuen
Title: Reliability of automatic sprinkler systems in shopping centres in Hong Kong
Degree: M.Sc.
Year: 1999
Subject: Fire sprinklers -- China -- Hong Kong
Fire sprinklers -- China -- Hong Kong -- Mathematical models
Shopping malls -- Fires and fire prevention -- China -- Hong Kong
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Building Services Engineering
Pages: xii, 87, [51] leaves : ill. (some col.) ; 31 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1471901
URI: http://theses.lib.polyu.edu.hk/handle/200/1683
Abstract: Shopping centres have been very popular in Hong Kong in the past two decades. Sprinkler systems became mandatory for shopping centres in 1973. However, some sprinkler systems may not be maintained properly, especially in those small shopping centres managed by small property management companies. Furthermore, the sprinkler systems are often regarded as if they can function effectively even without any maintenance. As a result, many sprinkler systems installed in shopping centres have become antiquated and are poorly maintained. Their effectiveness in fire extinguishment is in doubt. The reliability of automatic wet pipe sprinkler systems in shopping centres was studied and analyzed with the aid of the fault tree analysis technique. A mathematical model was developed from the fault tree diagram to estimate the average statistical downtime of sprinkler systems. The study is carried out to identify the weak areas of typical wet pipe sprinkler systems and to ascertain if the sprinkler systems installed in the shopping centres in Hong Kong are as effective as they are perceived by the general public. Designs of most wet pipe sprinkler systems are similar. A typical schematic diagram is produced for the purpose of analysis. The major components of the system are identified and their failure modes are defined. The fault tree analysis technique is used to develop a fault tree and subsequently, a mathematical model for this generic system. The mathematical model is a useful tool for analysis because the mean fractional dead time or the average statistical time when the system is in failed state, can be estimated by inserting the respective failure rates of the components and sub-systems of the sprinkler system into the mathematical equation. It is found that the system shutdown rate, which may be caused by maintenance or repair of the system components, has the greatest impact on the overall system failure probability. The system is less susceptible to the failure of other components such as the sprinkler pumps and the emergency generator because of the redundancy arrangement in these sub-systems. The conclusion conforms to findings in the literatures that water being shut-off is the main cause of failure of sprinkler system. The effect of the shutdown duration on the overall system failure probability is explored and corresponding measures are recommended in this study. To conclude, automatic sprinkler systems are not maintenance-free systems. Instead, they require close attention and proper maintenance in order to be effective and reliable in fire extinguishment.

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