| Mechanical Systems
Three separate air-handling systems circulated and
conditioned air
in the building. None of the systems was equipped
with smoke detectors or
controls to shut the fans down in order to prevent
recirculation of smoke.
The first sign of a fire in the building was the presence
of smoke in the
lobby that had been circulated by the air handling
system.
Two air handling systems, located in the basement,
were dedicated
to the three floors below grade and the first through
fifth stories,
respectively. Each of these systems heated, cooled,
and mixed air, moving
fresh supply air to the floors through a large air
shaft near the center of
the building. A separate shaft was provided for returning
air from these
floors to the air handling units in the basement.
Supply air was ducted to
registers throughout these areas, while return air
was transported to the
shaft through a common return air plenum above the
original plaster
ceiling. The dangerous accumulation of fire gases
on the third floor is
believed to have occurred in this return air plenum
as well as a secondary
void space between the original ceiling and a “dropped”
ceiling.
Floors five through nine received air from a shared
mechanical unit
located between the eighth and ninth floors. Individual
units were used for
heating and cooling in the guest suites. Return air
circulated through the
corridors? The provision of a separate air handling
system for the upper
floors prevented smoke from the fire on the third
floor from being
recirculated to the guest rooms by the air handling
system.
Elevators
Although the elevator shafts did not contribute significantly
to
smoke spread, some occupants used the elevators rather
than stairways to
evacuate the building. A single bank of two elevators
served all floors
except the mechanical penthouse. At least one hotel
guest reported that
he left the building via an elevator after becoming
aware of the fire.
3 The use of corridors for return air purposes is
now expressly prohibited by several
model codes. See Section 803.1 of the BOCA National
Building Code, 1990 edition and
NFPA 90A-(89), Section 2-3.11.1.
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