What is a smoke control system?
Smoke and products of combustion are considered one of the greatest hazards to life safety in the built environment.
Even considering the exceptional safety and proven suppression track record of automatic sprinkler systems, early detection and notification by automatic fire alarm systems, and other features of fire protection and life safety, we still need to deal with smoke in our buildings, and how that smoke could potentially impact occupants.
A smoke control system is a means to prevent the impact of smoke and extremely hazardous products of combustion on egressing occupants and occupants located within a building, that may not be in immediate fire area.
We want to keep deadly smoke from preventing people trying to escape a building.
These systems are aimed at providing tenable conditions for egressing occupants from their initial location in a building throughout their complete egress.
Smoke is airborne solid and liquid particulates as well as gases that are products of a material undergoing pyrolysis and combustion; these products then get mixed with entrained air and disperse as a smoke plume and smoke layer, quickly spreading throughout compartments and a building.
Smoke contains reduced levels of oxygen and the presence of carbon monoxide, carbon dioxide, hydrogen cyanide, hydrogen chloride, and other toxic gases. These conditions result in physiological and psychological effects on occupants, that need to be reduced through the use of a smoke control system.
Overall, we characterize the goals of smoke control systems into one of the following four categories:
Smoke control systems maintain a tenable environment along egress routes during the time required for evacuation
Smoke control systems limit the migration of smoke beyond the fire area for the entire duration of the fire event
Smoke control systems provide conditions outside of the fire area that enable emergency personnel to conduct search and rescue operations and to locate, control, and extinguish a fire
Smoke control systems assist in post-fire smoke removal.
Smoke control systems are aimed at preventing the unwarranted movement of smoke through various occupancies including high-rises, atriums, hospitals, arenas, and more occupancies where the building code requires such. To achieve the overall goal of providing a tenable environment for egressing occupants, this is typically provided through either a pressurization approach, exhaust approach, or air-flow method to control, limit, and prevent the movement of smoke from the area of origin to adjacent spaces. We want to keep a safe environment in a building long enough for everyone to escape.
One of the most prominent fire events in the United States that made us take a strong look at smoke control systems was the MGM grand fire in Las Vegas, Nevada on November 21, 1980. This building was 26 stories in height and at the time of the fire had 5,000 patrons located within. A fire originated on the 1st floor in the Deli space due to an electrical fire. It took 6 minutes for the fire to become fully developed across the first floor casino space after it was discovered. Although lack of sprinkler protection on the ground floor due to an exception was also a contributing factor, it is important to note that of the 85 total deaths that occurred from this fire, 72 percent of these deaths were on upper floor levels. Thus, it was clearly building egress system that proved to be the deadliest factor, specifically non-protected vertical openings including stairwells that quickly became smoke-filled. This fire, among numerous others, pushed the significance of smoke control systems in the modern code structure.
In this video, we gave you a strong overview of what a smoke control system is, from defining the hazards and characteristics of smoke, the goal of these systems, and a brief introduction to the approaches utilized in smoke control system design.
I’m David Stacy, and this is MeyerFire University.