FRAME Calculation examples book. - FRAME Fire Risk Assessment ...

F.R.A.M.E.
The building was equipped with 30 overhead sprinkler systems and 17 in-rack sprinkler
systems. The facility was supplied by a 10 " looped water main connected to a 20" municipal
water main. A 1,135,600 litre water tank provided an additional water supply. Two 9,462
litre/min fire pumps, one electric and one diesel, were connected to the fire protection system.
The electric pump was connected to the water mains and the diesel pump was connected to
the water tank.
The sprinkler system over the area of the first fire was designed to supply a density of 18 litre/
min/ ml. However, there were no in-rack sprinklers in this area. The ceiling was located about
22m above the floor and 16m above the highest level of racks.
A fire alarm system monitored the sprinkler systems, valves and fire pumps. Alarm and trouble
signals were transmitted to an on-site security office that was continually monitored. Alarm
signals were transmitted to an off-premises supervising station that was responsible for
notifying the fire department. At the time of the first fire, there were 15 employees in the
building.
The first fire, reported at 5.32am, quickly involved the combustible materials being stored in
the 6.4m high portable racks. When the fire was discovered, it was reported to have fully
involved the three-tier rack, and was extending to the ceiling. The rapid fire spread can be
attributed to the combustible nature of the products being stored and their storage
configuration. Employees tried unsuccessfully to fight it using portable fire extinguishers and
occupant-use fire hoses. The overhead sprinkler system, that was located approximately 15m
above the top level of the racks, activated at 5.32am, but did not extinguish or control the fire.
The fire was extinguished by the fire department using an interior attack.
The New Orleans Fire Department responded at 5.37am with an initial attendance of six
appliances. The first appliance arrived at 5.40am and reported heavy smoke showing. Eight
additional units were dispatched at 5.42am. The fire was reported to be coming through the
roof at 5.43am. Fire fighters began an interior operation to contain the fire. It was declared
under control at 8.44am, and extinguished at 11.54 am.
Once fire control had been achieved, all the sprinkler systems in the facility were manually
shut down by closing the individual valves on the risers. According to the New Orleans Fire
Department, this was because numerous sprinkler heads had opened throughout the
warehouse, causing extensive water damage. At 2.20pm, electrical power was restored to the
conveying system within the racks in the south-central portion of the building. Damaged wiring
in this area arced and ignited combustible materials. As soon as the second fire was
discovered, facility personnel began opening the recently shut valves on the ceiling and in-rack
sprinkler systems. The catastrophic damage that followed is attributed to the fact that the
sprinkler systems were shut down throughout the entire facility. Consequently, the sprinkler
system was overwhelmed, and the fire department had to mount a defensive operation.
This second fire was declared under control on Wednesday, 27 March 1996 at 9.08pm, six
days after the first fire.
The warehouse and distribution portion of the building, and its contents, were destroyed by the
second fire. There was minimal fire and water damage to the area located on the other side of
the fire separation wall. There was some structural damage to the walls due to the stresses
placed on this portion of the building by the collapsing roof on the east side of the fire
separation wall. On this side, structural collapse was widespread.
The devastation caused by the fires was the result of a number of factors, including:
Excessive clearance between the ceiling sprinklers and the top of the storage racks in the area
of fire origin for the first fire, lack of in-rack sprinkler systems ,shutting off all the sprinkler
systems in the building following the first fire restoration of electrical service without
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