Fire alarm

Fire alarm bell installation

Brief:

Measurements of fire alarm sound pressure levels (SPLs) in five elder care centres showed that the sound output of a fire alarm can be depreciated after installation [1,2]. The alarm level of a new fire alarm installation could alert most of the building occupants but could not awaken a sleeping person.Subjective ratings on the fire alarm audibility in terms of minimum fire alarm SPL were studied with 230 awaken subjects divided by two age groups (22–48 and 66–88) in the five elder care centres. A higher perceived SPL is preferred for the elder age group to obtain the same subjective rating, when compared with the younger age group.Correlations between the subjective ratings and the measured SPL show that the alarm SPL of 65 dBA can alert most of the occupants in daytime, but expressed a preference that the alarm SPL be increased.The results show that the minimum required fire alarm SPL is 74.5 dBA, which agrees with the recommended alarm SPL at bed head of 75 dBA in the design guidelines. The depreciation of SPL of alarm sounder and the preferred SPL of occupants should be considered in designing a fire alarm system for elder care centres.

It is important to understand the occupant behavioural response in fire emergency in high-rise buildings so that proper decisions for a fire safety management plan could be made [3]. Behavioural responses of building occupants to an audible fire alarm cue in high-rise buildings in Hong Kong were investigated. Fire alarm audibility of a sustained alarm cue and occupant's past experience regarding the fire alarms could be key parameters for further investigation [4,5].

Reference:

[1] Wong LT, Leung LK, 2005. Minimum fire alarm sound pressure level for elderly care centres, Building and Environment 40(1) 125-133.

[2] Wong LT, Leung LK, 2004. Optimum sound pressure level of a fire alarm sounder for elderly, Proceedings of Shenyang-Hong Kong Joint Symposium 2004 on Healthy Building in Urban Environment, 29-30 July, Shenyang, China, pp. A103-A110.

[3] Wong LT, Fong NK, Sui WH, 2009. A survey of occupant response towards an audible fire alarm, International Journal for Housing Science 33(4) 249-258.

[4] Wong LT, Chak SY, 2000. Audibility and occupant response towards the audio fire alarm in high-rise residential buildings, International Journal for Housing Science and Its Applications 24(4) 315-327.

[5] Fong NK, Wong LT, Sui WH, 2005. Behavioural responses to fire alarm in high-rise buildings in Hong Kong, Proceedings of the 2005 Asia-Pacific Conference on Risk Management and Safety-Challenges in Engineering Applications and Advances in Technologies, Hong Kong Association of risk Management and Safety, Kowloon Shangri-La Hotel, Hong Kong, 1-2 Dec, pp. 184-191.