Various important full-scale smoke control experiments have been conducted at the 10- storey experimental fire tower at the National Research Council of Canada (NRCC), which includes a combination of corridors, stair and lift shafts. The focus of the experiments performed at the NRCC tower has been on establishing the performance of stairwell and lift shaft pressurisation schemes [e.g. Tamura & Klote, 1987] and in providing data for numerical model validation [e.g. Hadjisophocleous et al, 2002]. Experiments have also been undertaken at the experimental building-fire facility at Victoria University of Technology, Australia [see, e.g., He, 1999].
For the purposes of the review, and the project generally, the common access egress path was taken to consist of the following physical components, starting from the fire compartment or dwelling. Where a component is labelled as 'optional', this refers to the fact that this component will not necessarily be present in all cases. As noted already, lifts and lift shafts have been omitted from the.
Fire compartment. The fire will generally be considered as being within a space open directly to the front door of the fire compartment. Optionally, there may be an internal lobby separating the room of fire origin and the front door.
Common corridor (optional). There may be one or more corridor / lobby section(s), separated by an appropriate form of compartmentation, e.g. fire door.
Stair lobby/vestibule (optional). A separate enclosure to provide additional protection to the stair or an area of refuge.
The final stage, at the level of final escape, may then include a protected lobby or corridor, or the stair may open directly to the outside.
Before reviewing the various schemes, it is worth noting here the principle mechanisms, or forces, that influence the movement of smoke from the fire source to the rest of the building. The following mechanisms are the principle ones determining the transport of smoke from the location of fire origin.
Thermal expansion due to heat from the fire. During the growing stage of a compartment fire, provided there are sufficient opening to the compartment then the volume of the gas (air and smoke) inside the compartment will increase in proportion to the increase in absolute temperature inside the compartment. The increased volume is forced out of the compartment into the adjoining spaces. The pressure difference between the compartment and adjoining spaces is determined by the opening area(s), size of the compartment and the rate of temperature rise. Once steady conditions are reached inside the compartment of fire origin, the pressure difference (due to expansion), and the associated expansion flow, reduces to zero.
Buoyancy forces due to the fire gases. Once the fire is no longer growing, the flow of smoke out of, and air into, a compartment ventilated to adjacent ambient conditions is (ignoring wind effects etc) driven by the buoyancy forces associated
© Building Research Establishment Ltd 2005