Fire Suppression Systems. Federal Building and Fire Safety Investigation of the World Trade Center Disaster.
Fire Suppression Systems. Federal Building and Fire
Safety Investigation of the World Trade Center Disaster.
Hopkins, M.; Schoenrock, J.; Budnick, E.
NIST NCSTAR 1-4B; 278 p. September 2005.
World Trade Center; high rise buildings; building
collapse; disasters; fire safety; fire investigations;
terrorists; terrorism; fire hoses; hydraulic analyses;
spray density; sprinkler systems; standpipes; fire
suppression; water supply; codes; standards; sprinklers;
The National Institute of Standards and Technology
(NIST) conducted a building and fire safety
investigation of the World Trade Center (WTC) disasters.
The work documented in this report was performed in
support of the investigation of active fire protection
systems. Specifically, this effort involved
documentation and evaluation of the automatic sprinkler
and standpipe/pre-connected hose systems and their
associated water supplies in WTC 1, 2, and 7. An
extensive literature review was performed in order to
document the installed fire suppression features.
Hydraulic analyses were performed to provide estimates
of the baseline capabilities of the suppression systems
as well as capabilities under different fire incident
scenarios, including the events of September 11, 2001.
In general, the installed water supplies, automatic
sprinkler, and standpipe/pre-connected hose systems in
WTC 1, 2 and 7 met or exceeded the capabilities of
systems typically installed to protect high-rise office
buildings. The sprinkler systems were capable of
providing adequate water densities to areas as much as
two or three times the typical design areas.
Based on initial building damage estimates, the
sprinkler and standpipe systems sustained considerable
damage in the impact areas of WTC 1 and WTC 2. However,
even if the sprinkler systems had remained fully
operational and had been designed to protect higher
hazard levels (e.g., Extra Hazard), the size, number,
and extended area of the initial fires would have opened
a large number of sprinklers, involving floor areas
significantly larger than those associated with the
required water demand for the design area associated
with the installed systems. For the most part, the
water supplies provided redundant sources of water for
the standpipe and sprinkler system infrastructures.
However, the typical floor level sprinkler systems were
installed with a single connection to a sprinkler riser,
providing the potential for single points of failure.
The standpipe/pre-connected hose systems were consistent
with the applicable requirements of the Building Code of
the City of New York, but were not consistent with the
minimum flow rates and durations required in National
Fire Protection Association (NFPA) 14. In addition,
selected areas in all three buildings, including the
generator fuel day-tank enclosures on several floors in
WTC 7, were not protected by automatic sprinklers.