A case study on the unwanted fire alarms

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A case study on the unwanted fire alarms

 

Author: Ip, Sik-wing
Title: A case study on the unwanted fire alarms
Degree: M.Sc.
Year: 1997
Subject: Fire alarms
Fire alarms -- China -- Hong Kong -- Case studies
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Pages: x, [184] leaves : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1250494
URI: http://theses.lib.polyu.edu.hk/handle/200/2456
Abstract: The objective of this dissertation is to study the unwanted fire alarms of the automatic fire detection system and the fire fighting systems of a building. A survey was conducted to understand the false alarms patterns and then analyze the causes of false alarms. Results obtained are used for recommending remedial measures to minimize future occurance of false fire alarms. A building of an eminent public listed company located in Causeway Bay, Hong Kong was selected as the sample building. Three years of false alarm data of the Automatic Fire Detection System and other fire fighting systems were collected. A site survey was conducted to determine the physical environments of the fire detectors. From the false alarms records provided by the Company, analysis on three hundred collected samples were carried out. Results reveal that a frequency of 3 to 4 days (or twice a week) of false alarm was reported. Over 90% of the false alarms come from the Automatic Fire Detection system and only about 10% come from the manual call points and sprinkler system. This is annoying to the occupants and wasted time and resources of fire brigade. A "Cry Wolf Syndrome" would result in the alarm being ignored by the occupants until the fire has become highly destructive and life threatening. Most of the false alarms come from the category of "Smoke Detector" and "Other Reasons". The category "Other Reasons" including those false alarms arising from defective components, power supply problem, unstable control panel, improper operation of control panel, transmission line fault, decoration/renovation works, services, smoking, accidental events and other unidentified reasons. All these causes could be attributed to POOR maintenance and management. The causes of smoke detectors are mainly because of dust, air current, moistures, temperature and smoking particles. Aging effect of the detector is another problem. Remedial measures have to be made in using smoke detectors. The percentage weightings of false alarms are 41% (1994), 70% (1993) and 30% (1992) for "Smoke Detector" and 38% (1994), 18% (1993) and 61% (1992) for "Other Reasons". Over 90% of false alarms would be eliminated if these two factors were excluded. Three recommendations are made to reduce false alarms:- 1. Performance based design and proper selection of fire detectors for the system is necessary. 2. Proper maintenance and management to the fire fighting systems are recommended. 3. Heat detector to be used, if feasible, as demonstrated by a sample calculation.

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