Simulation of an Attic Fire in a Wood Frame Residential Structure–Chicago
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Simulation of an Attic Fire in a Wood Frame Residential Structure–Chicago

August 23, 2019


This video provides an
overview of an analysis conducted by the
National Institute of Standards and
Technology or NIST to provide insight,
into the dynamics of a fire that resulted in a
line of duty death. On November 2, 2012 a fire in a two and one-half
storey residential structure claimed the life of a Captain
of the Chicago Fire Department. NIST examined the fire
dynamics of this incident at the request of NIOSH
and the Chicago Fire Department. At 5:16 in the afternoon
dispatch called a still alarm for smoke in the area. Battalion 19 arrived on scene
within a minute of dispatch. He reported a working
fire with heavy smoke showing from the rear and front
of the structure’s attic. Battalion 19 made entry
through the front door and took the stairwell to survey the interior
of the second floor. He observed the
light haze of smoke throughout the second floor and a glow around the rear
door to the enclosed porch. Battalion 19 returned
to the front door and met the Engine 123
Captain and firefighter. Battalion 19 made entry to
the first floor apartment and worked his way to the
rear of the structure. From the inside,
he opened the door that led to the rear foyer
on the backside of the house, and noticed heavy fire
in the enclosed porch and rear stairwell area. Within five minutes
of the dispatch, the engine 123 Captain
and firefighter were on the second floor where they advanced
a charged hose line toward the rear door
of the apartment. Another firefighter went to
the rear of the structure to check doors. He first went to
the basement door which he was unable
to force-open. Then he made entry
to the enclosed porch at the first floor level. He stated that he noticed
fire light up in the stairwell. He kicked in the locked door
that connected the porch, the rear foyer. He saw no fire on the
first floor and backed out. Approximately 6 minutes
after arrival on scene, Battalion 19 radioed
the engine 123 Captain that there was heavy fire in the
enclosed porch and attic area and that engine 49 was going
to put water on the fire around the rear
attic window. There was no acknowledgment
from the Captain. The Engine 123
firefighter paramedic and four other firefighters were near the kitchen
on the second floor when they heard a
loud commotion. The engine 123
firefighter paramedic heard the Captain yell, “Get out of here”. The Engine 123 firefighter
paramedic yelled Mayday as he tried to
get the Captain and the Engine 123
firefighter untangled. The other four firefighters
heard the verbal Mayday and a Mayday was
transmitted over the radio. The firefighters grabbed
the Engine 123 Captain and got him down the stairs. CPR was successfully performed
on the Engine 123 Captain. Unfortunately, he succumbed
from his injuries shortly after arriving
at the hospital. NIST’s Fire Dynamics
Simulator or FDS was used to provide
insight into the dynamics of the structure fire. The inputs and details
for the FDS simulations are documented in the
NIST Technical Note 1838. The fire started
in the attic and spread down through an
opening in the enclosed porch on the rear of the structure. The heated gases of the fire increased the pressure in
the attic and porch area. The increased pressure
forced the smoke and flames out of the gable ends
and eaves of the attic as well as the holes
burned through the walls of the enclosed porch. The fire in the attic
and rear porch areas was also ventilation
limited or fuel-rich. The spread of
fire and hot gases into the second floor of the
structure was initially stopped by a closed steel-faced
wood-framed door. After exposure to elevated
temperatures and pressure from the fire in
the porch area, the wood-frame of
the door decomposed and the upper portion
of the door collapsed, allowing the higher
pressure of hot gases to flow into the
lower pressure hallway where the Captain
was located. The door failure resulted in
the establishment of a flow path between the higher pressure and
higher temperature conditions in the enclosed porch, and the lower pressure and
lower temperature conditions in the hallway and kitchen
areas of the second floor. This video shows the
second floor plan view. The temperature estimates are
shown at 6 feet above the floor. The temperature
of the gases that flowed into the
hallway at this height exceeded 500°F within
seconds of the door failing. The model results
presented so far only considered the
flow into the hall with the top half
of the door open. What if the door folded
over and then fell open? The images show the comparison
of the flow results with the half-open door
and the full-open door. There have been many
previous fire incidents in which changes
in the flow paths have had an adverse impact on
firefighter and occupant safety. Fires with rapidly developing
or changing flow paths are significant hazard
to firefighters. The development of a flow
path could be caused by the failure of a
component of the structure such as a door, window
or portion of a ceiling, wall or floor. Environmental
conditions such as wind can generate hazardous thermal
conditions within a flow path. Uncoordinated ventilation
or uncontrolled doors can also be the cause of
increased thermal hazards within a flow path. In this fire incident, the thermal degradation and
failure of the rear porch door resulted in a rapid increase
in temperature and fire gases in the hallway, conditions that change
from tenable to untenable within seconds. Prediction of
the failure mode and failure time of
a building component is not a reasonable
expectation given the large
number of unknowns that the firefighters
face on the fire ground. Research has been
conducted by NIST and UL with fire departments
across the country on exterior fire attack. The studies have shown that
the application of water from the exterior into the
fire area of a structure prior to the start of
the interior operations can significantly improve
the safety of firefighters by reducing the thermal
hazard from the fire and reducing the potential for developing high
pressure high velocity, hot gas flows within
the structure. The exterior attack should be made with a straight
stream or solid stream. When sizing up a
structure fire, choose your tactics with
potential flow paths in mind. Recalled it in a flow path heat moves from a region
of high pressure to a region of low pressure. Firefighters located
in the flow path downstream of the fire can be exposed to
deadly levels of heat. Therefore, it is critical that crews coordinate
ventilation and suppression tactics. For more information
on this incident, see NIOSH Report 2012-28
and NIST Technical Note 1838. These reports and
other information on flow paths
and fire dynamics can be found at the NIST
firefighting technology website. For updates, follow
NIST on Twitter.

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  1. Thanks for checking out our videos. Please add your comments and let us know what you think.We will be reviewing and then posting comments as long as they are on topic, respectful and do not promote specific products or services.

  2. Thanks to NIST, UL, NIOSH,and especially the CFD members who were open and honest about this.  I consider Herbie as a friend and I think he would be proud of this work if it ultimately will save at least one FF's life.

  3. Thanks NIST for providing this easy-to-understand explanation of flow-path and how it caused the loss of own of our own. I think many of the explanations of flow-path can be theoretical or "bookish" and hard to grasp for many of us. Through his service and sacrifice and this research Captain Johnson's loss will aid many other firefighters.

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