The containment of smoke and other toxic gases during a fire is a crucial element of fire and life safety. At times, it’s easy to get bogged down in the little details of life safety compliance. The codes, requirements, and citations from Authorities Having Jurisdiction who enforce these codes seem to be the driving factor for keeping life safety systems in working order. During this process, we tend to lose sight of the bigger picture and the reason the codes were created in the first place. When your fire barriers are non-compliant, you are not only jeopardizing your facilities compliance, you are jeopardizing the lives of your building occupants.
Firestopping is the process of installing specific materials and fire-rated UL system specifications to resist or stop the spread of fire and smoke through openings and penetrations in fire-rated walls, floors, and floor/ceiling assemblies. Smoke can fill a 20 by 20 foot room through a pencil size hole in less than 3 minutes. Over half of fire-related deaths occur in rooms where the fire did not originate and ¾ of all fire deaths are caused by smoke inhalation. This is why proper firestopping is so important. There have been several major fires in history that reveal the true consequences of what happens when firewalls are neglected or firestop systems are not properly installed.
Browns Ferry Nuclear Plant
On March 22, 1975 a fire broke out in Browns Ferry Nuclear Plant when a worker tried to test the material for smoke containment. He held a candle under the fire/air seal. The temporary sealing material turned out to be highly combustible, and caught fire. It ignited and burned, with fire rapidly spreading and affecting critical power and station control systems. The fire damaged enough cables that operators could not monitor the plant normally and emergency repairs had to be performed. More than 1,600 electrical cables were affected, 628 of which were important to plant safety.
What were the life safety implications?
This disaster highlighted the need for regulations on using appropriate firestop material. Urethane foam was used as a firestop material in electrical conduit pipe penetrations, which was highly combustible and lead to the spread of the fire at a very fast pace instead of slowing the spread of fire as intended. Some senior personnel at the plant thought that the urethane sheet foam used to seal the cable penetrations was fireproof. As a result, an untested material not meant for use as a “Firestop System” caused a major disaster and set a precedent for future penetrations to be sealed in a particular way. Afterwards, a prescriptive fire code was put in place for U.S. nuclear power stations to provide the best assurance that no single fire can destroy the reactor control room’s ability to safely shutdown the reactor following a significant fire.
MGM Grand Hotel
On November 21, 1980 a fire at the MGM Grand Hotel in Las Vegas, Nevada was started by “heat from an electrical ground-fault within a combustible concealed space in a waitresses serving station.” Eighty-five people were killed in the fire and nearly 700 were injured from the fire and smoke, making it the third highest fatality count hotel fire in the US (NFPA, 2008). While the fire primarily damaged the ground floor casino and adjacent restaurants, most of the deaths were caused by smoke inhalation on the upper floors of the hotel.
What were the life safety implications?
One of the life safety issues was openings in the vertical shafts, stairways, elevator hoist ways, and the seismic joints which allowed the toxic smoke to spread throughout the building all the way to the top floor. Later newspaper articles indicated that there were 83 building code violations, design flaws, installation errors and materials that were identified afterward that contributed to the magnitude of the fire and smoke spread. Not more than three months after the fire, the state’s building and fire codes were revised to have the most stringent fire-sprinkler and life-safety requirements in the country.
Sometimes it’s necessary to look back on past mistakes to help guide our future decisions. The probability of these tragic events happening might be small, but the consequences are devastating. Disasters like these have shaped the life safety system industry and codes that are in place today. Firestopping helps to contain smoke and toxic gases to help stop it from spreading to other areas in the building. We need to take into consideration what firestopping does, and why it’s important that the penetrations in your barriers are properly sealed. Firestopping can increase the availability of escape routes for occupants and ultimately save lives.
Learn more about firestopping.