Interstate Bank Building
Fire;
INITIAL STAGES
At 2222 on the night
of the fire, the buildings two fire pumps were shut down
by the sprinkler contractor, and the combination standpipe
system was drained down to the 58th floor level to facilitate
connecting the new sprinkler system to the standpipe at
that level. Three minutes later, at 2225, employees of the
sprinkler system contractor heard glass falling and saw
light smoke at the ceiling level on the 5th floor. A manual
alarm was pulled but sounded for only a few seconds. It
is believed that the alarm was silenced by security personnel
on the ground floor.
At 2230, a smoke detector
on the 12th floor was activated and was reset by security
personnel. At 2232, three additional smoke detectors on
the 12th floor were activated and were again reset by security
personnel. At 2234, four smoke detectors on the 12th floor
were activated and reset.There was heavy exposure of flames
to the windows on successive floors as the fire extended
upward from the 12th to 16th floors. The flames were estimated
to be lapping 30 feet up the face of the building. The curtain
walls, including windows, spandrel panels, and mullions,
were almost completely destroyed by the fire. There were
no "eyebrows" to stop the exterior vertical spread,
and fireground commanders were concerned about the possibility
of the fire "lapping" higher to involve additional
floors.
Minor fire extension also occurred via poke-through penetrations
for electricity and communications, via HVAC shafts, and
via heat conduction through the floor slabs. A minor fire
occurred in a storeroom on the 27th floor, ignited by fire
products escaping from an HVAC shaft that originated on
the 12th floor. This fire self-extinguished due to oxygen
deficiency, but could have greatly complicated the situation
if it had continued to burn. The secondary extensions were
minor compared to the perimeter fire spread at the curtain
walls.
The fire extended at a rate estimated at 45 minutes per
floor and burned intensely for approximately 90 minutes
on each level. This resulted in two floors being heavily
involved at any point during the fire. The upward extension
was stopped at the 16th floor level, after completely destroying
four and one-half floors of the building.
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