Investigation of the effects of pressure variation on water mist qualities for fire-fighting
Lee, Jaclyn Jie Yin.
Date of Issue2009
School of Mechanical and Aerospace Engineering
This project is concerned with parametric study on the effectiveness of fire extinguishment using water mist by pressure variation for a given mist gun nozzle design. This report consolidates the observations made during the experiments conducted at the Nanyang Technological University (NTU) and Singapore Civil Defence Academy (CDA) involving the production of water mist at different pressures produced by the mist gun used by the Singapore Civil Defence Force (SCDF). It aims to investigate how the variation of pressure would affect the different parameters involved for effective fire-fighting, so that a proper pressure and hence power requirement can be specified to increase the effectiveness of water mist systems currently used by the SCDF. The experiments were conducted to determine the effect of pressure on the parameters of spread, range of throw and extinguishment speed. It was found that the spread of the water mist particles generally increases with pressure. However, there is a limit to which the spread will be able to reach. This is dependent on the design of the nozzle. Similarly, the range of throw, too, increases with pressure, reaching a limit where further increases in pressure would not lead to further increases in the range of throw. Besides its effects on spread and range of throw, it was found that initial increases in pressure cause the rate of extinguishment to increase but subsequent increases led to a slower extinguishment speed. There is therefore an optimum pressure level for a given mist gun nozzle design in effective fire fighting. The results obtained from these experiments could also be used to develop a portable backpack system for use by the SCDF.
Final Year Project (FYP)
Nanyang Technological University