Study of the effect of ventilation rate and platform’s ceiling height on visibility in typical MRT underground station’s fire
In case of a fire building visibility is a major important aspect to ensure that all the occupant can evacuate safely. Because of the smoke flow which is a buoyant – driven flow and due to the installation of near – stairway drop wall that prevent smoke spread to the upper level of the MRT underground station for several period, a fire occurrence at the platform level (which is the location of ignition source in this study) could endanger the safety of passenger at platform’s level even more caused by the prevention of the smoke spread which could increase the smoke layer’s thickness substantially. This phenomenon give rise to faster increase of opacity which reduce significantly the occupant’s capability to looking for the means of escape (e.g. stairs) when the emergency situation arise, such as fire. So, to avoid such situation which endangers occupant’s life safety, especially at platform’s level, a sufficient mechanical ventilation rate should be known and must be installed at the ceiling of MRT Underground Station. The Fire Dynamic Simulator (FDS V553) code is used to simulate or predict smoke spread and the capability of mechanical ventilation to extract smoke and toxic gases due to fire. In this study, performance of ventilation rates (6000 m3/h and 7000 m3/h) toward extraction of the smoke based on visibility for various locations are compared according to the platform’s ceiling height (3 m and 4 m) and Heat Release Rate (HRR) of 50 MW.
Keywords: ventilation rate, visibility, MRT