Saving lives with smoke vents
by Thomas Renner
A General Motors plant in Livonia, Mich., was considered a state-of-the-art facility for the post World War II-era when it was built in 1949. Four years later, a fire destroyed the expansive facility, killing six people and throwing 45,000 workers out of jobs, at least temporarily. Only an office building and a smaller power plant were reported salvageable of the 139,355-m2 (1.5-million sf) facility.
Sparks from a welder’s torch started the blaze, and the building went up in smoke in a matter of minutes. By the time firefighters arrived, there was very little they could do. The roof had partially collapsed, making the building too dangerous to enter. The fire burned itself out the following day, but not before the smoldering wreckage spread out across 14 ha (34 acres) resulting in a $50 million (almost $500 million in today’s dollars). It is considered the most destructive industrial fire in U.S. history.
At the time of the fire, the building and production processes were deemed fully up to all established fire and safety codes, and the building itself was said to have “the most modern fire-prevention and fire-quenching equipment.” However, a Fire Engineering article published in September 1953 reported the building “was enlarged several times, and there were no effective firestops to divide up the large floor area. Also, the sprinkler system did not cover the entire plant.” Later reports said no more than 20 percent of the building was sprinklered, and there were no fire walls, partitions, or roof vents.
Without a way to escape, the smoke, heat, and fire were trapped inside the building, creating temperatures intense enough to melt and warp metal girders and cause structural damage to roof trusses, which ultimately led to the collapse of the building.
“Two of the biggest challenges we face in fighting any fire are heat and smoke,” said Steve Martin, battalion chief for the Columbus, Ohio, Fire Department. He watched a fire at Dick Cold Storage in Columbus destroy the building in August 2016. That building also lacked smoke vents. “The heat of the fire radiates on everything surrounding it, causing the flames to spread and rapid degradation of structural elements.”
Understanding smoke vents
In June 2018, Dick Cold Storage opened a new, state-of-the-art facility with automatic smoke vents. The vents, manufactured by The BILCO Company of Connecticut, allow for the escape of smoke, heat, and gasses in a burning building.
“Vents will allow for the removal of heat and smoke will potentially slow the spread of fire,” Martin said. “They will also permit firefighters to see and enter the building, to possibly extinguish the fire early, preventing the entire building from becoming a loss.”
After the fire at Livonia, building codes and common design practices changed. One of the new practices included the installation of smoke vents on ceilings of storage buildings, manufacturing facilities, and warehouses.
Regulations for smoke vents in commercial structures are outlined in the National Fire Protection Association (NFPA) 204, Standard for Smoke and Heat Venting. NFPA 204 provides calculations to determine the required dimensions and spacing of smoke and heat vents. The number of smoke vents depends on the size of the building or area protected, the height of the ceilings, and the depth of the expected smoke layer, according to Robert Solomon, PE, division director for NFPA.
The number of smoke vents required is also determined by local building and fire codes and by the type of commercial structure. Dick Cold Storage has 169,902 m3 (six million cf) of storage space, which is the usual unit of measurement for the cold storage industry.
“In the cold storage industry, it is not so much about square feet as it is about cubic space,” said Rob Adams, a partner at Tippmann Innovation who helped design the new building. “It is about getting pallet positions. You want to maximize square footage, so you generally build horizontal instead of vertical. You are refrigerating the same footprint. It is significantly more costly to build a refrigerated building.”
In 2017, architects designing the Hale Centre Theatre in Utah had workers install 20 acoustical smoke vents. The theater stretched out over 12,356 m2 (133,000 sf)—about 9290 m2 (100,000 sf) larger than the cold storage facility—and only required two more smoke vents. The acoustic vents were required, however, to limit noise intrusion from interstate roadways and a nearby airport.
“A cold storage facility may have a greater fuel load than a theater, which correlates to a design with a higher expected heat release rate, greater temperature outputs, and an increased smoke production rate, which may require larger, more closely spaced vents,” Solomon said. “The design influences the number, size, spacing, and activation requirements. The theater scenario is largely directed at stages and is essentially a key occupant life safety feature.”
Without vents to exhaust the smoke, the smoke is contained within the building, said William Koffel, PE, FSFPE, and president of Koffel Associates.
“This could impact egress, cause increased property damage, and hinder the efforts of first responders,” he said.
Koffel said if the incident commander determines that ventilation is necessary and appropriate, firefighters will manually cut holes in the roof to serve as roof vents.
“Many of these buildings are light steel construction and there may be concerns with the integrity of the roof upon which the firefighters need to work,” he said.
All information listed in this section was submitted by The Bilco Company.
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