The fire area contained more than one automatic sprinkler zone and several unsupervised
control valves; these valves were not chained and locked in the open position.
One of these valves was found closed after the fire during the investigation stage. There
were automatic sprinklers discharging water during most of this fire as documented by the
dense white cold smoke and video tape of the scene as the front wall was moved. However,
it is possible that the sprinklers in the immediate area of origin were shut off. Investigators
found a closed control valve on the water supply to these sprinklers. No member of the
Chicago Fire Department reported closing the valve which was located in the fire area.
Because of the storage height, arrangement in the racks, solid shelves, and modest
water density, it is unlikely that this fire would have been controlled by the ceiling only
automatic sprinklers even if all of the systems had functioned properly. The back-to-back
racks with boxes two and three deep in each rack provided excellent conditions for a
shielded fire burning out of the reach of the automatic sprinkler discharge. Cardboard
boxes and their contents are very susceptible to smoldering fire development even when
the outside surface is water soaked.
The fire’s origin and cause had not been determined at the time this report was
prepared. Several electrical related causes were being investigated. Just before the fire
was observed, an electrician was working inside an electrical panel on the wall in the fire
area. Another cause being probed is the high intensity discharge lighting fixtures hung
from the bottom of the floor or roof above the racks. A fixture or light bulb may have
failed, ejecting hot materials which could have lodged in between the cardboard boxes.
The long commitment of fire department resources to this fire is typical of the
experience with records storage. The heavy equipment needed to gain access to the
interior is also typical for large windowless structures. The configuration of the rack
storage and the weight of water-soaked records and storage boxes present a potential for structural collapse of both the storage racks and the building. By themselves, paper
records and their storage means can provide a load very close to the capacity of the
structure; with the additional weight of the fire fighting water absorbed by the boxes and
their contents, a floor can become quickly overloaded. In addition, storage racks are
typically unprotected steel which will loose their structural stability when exposed to heat
and flame. They can also be overloaded by the extra weight of the water absorbed and
collected in the items stored in the racks. Failure of one rack may cause adjacent ones to
topple because of insufficient anchorage or simple overload.
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