FSE 120 Task B
docx
keyboard_arrow_up
School
Eastern Kentucky University *
*We aren’t endorsed by this school
Course
120
Subject
Industrial Engineering
Date
Dec 6, 2023
Type
docx
Pages
6
Uploaded by ChefNarwhal3048
Running Head: ANTICIPATED FIRE GROWTH
1
Task B: Anticipated Fire Growth
Kaylie R. Petrey
Eastern Kentucky University
FSE 120
May 8
th
, 2022
ANTICIPATED FIRE GROWTH
2
Early Fire Growth
The three seated couch has a large space heater directly beside it; this heater faces both
the couch and the blanket lying on the couch. Considering the blanket is on top of the couch I
would say that once the couch caught on fire and began to spread, the blanket would ignite as
well. From class we were shown that polyurethane foam, I am assuming the arms are padded,
releases intense heat, toxic smoke, and burns rapidly (Gorbet et al., 2016). So, I would estimate
that spread of the fire to the blanket would only take a few minutes. Polyurethane foam is also
known for melting into a burning liquid (Safety Data Sheet - qckslvr.com, 2014). Given that
polyurethane burns with intense heat, the carpet below would ignite within the first 10 minutes.
The carpet fire and lapping of the flames of the couch fire would likely cause the armchair to
ignite as well, I would estimate roughly 15 minutes, or more are needed for this to happen. The
chair also contains polyurethane, meaning it too will burn fast and hot. The canvas above the
chair will be destroyed as the high heat fire consumes it as fuel as well, allowing flames to climb
the wall. There likely will be nothing more than a completely charred frame left behind of the
canvas, couch, and armchair.
As the couch fire continues to spread, the fire would have spread across the entire couch
in about 10 minutes or less. The blanket will aid in this spread as it is thermally thin and quickly
consumed by the fire. The couch is thermally thick and will require more time to be consumed.
The canvas is also thermally thin, and that is why it will also be consumed at a much faster rate
than the thermally thick armchair. Given that the heat of combustion for polyurethane is 45,000
kJ/kg, couch fabric is 43,000 kJ/kg (
Nuclear regulatory commission,
2004), and the carpet is 25
kJ/kg it is safe to say this fire will spread fast (
Solids - densities
, 2022).
ANTICIPATED FIRE GROWTH
3
Flash Over
The heat release rate for flashover via the Thomas method uses the following formula,
Q
̇
fo
= 7.8A
T
+ 378A
v
√
h
?
. A
T
is the total area of the compartment excluding the area of the
vent opening, 2(3.66m)(3.66m)+2(3.66m)(2.44m)+2(3.66m)(3.66m)- door=71.44m
2
then I
calculated the area for the door opening, 0.91m x 2m= 1.82m
2
. Now, 71.44-1.82= 69.62m
2
. So,
A
T
is 71.44m
2
. A
v
is the area of the vent opening which is 1.82m
2
. The value for h
v
is the height
of the vent opening, 2m. Finally, we plug our numbers into the equation to get the final line of,
Q
̇
fo
=7.8(71.44)+378(1.82)
√
2
. Once solved, the answer is 1530.15 kW of a heat release rate is
required to cause a flashover (Gorbet et al., 2016). Based off my previous estimations in task A,
adding up to 7050kW to 7650 kW, the room can flashover.
Barauskas method use the following formula,
=wA
Q
̇
v
√
h
?
where
Q
̇
is the heat release
rate, A
v
is the area of ventilation opening, h
v
is the height of ventilation opening, and w is the
value for maximum 1500, minimum 600, and empirical best fit heat release rate 750. For the
purpose of calculating flashover, the value 750 is used and to calculate maximum heat release
rate the value 1500 is used.
=
Q
̇
750(1.82)
√
2
, this brings the answer to 1930.4 kW (Gorbet et
al., 2016). Barauskas method also proves that it is possible for a flashover based on my
estimations.
Fire Behavior
If the couch were to be ignited by the heater to the right, the fire would spread quickly to
the blanket. The couch contains polyurethane, which is known to burn fast and with Immense
heat. It would only take a few moments for the flames to get close enough to the blanket to cause
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
ANTICIPATED FIRE GROWTH
4
it to also ignite. The blanket is thermally thin, and because of that it will also burn fast as the fire
consumes it for fuel. The couch supplies a much larger fuel source for the fire, and so the fire
will keep spreading across the couch. Of course, the fire may also spread to the carpet and
armchair by the time one third of the couch is consumed and with the armchair we will see the
canvas destroyed by the climbing flames. Many of these factors also depend on where the couch
is ignited. Polyurethane foam melts and becomes a flaming liquid that is able to ignite other fuels
such as the carpet as well, expediting fire spread
(Safety Data Sheet - qckslvr.com, 2014)
. I
would say within 20 minutes, or less, all of the compartment will be ablaze based on the
characteristics of ignited polyurethane, the amount of fuel, and the video we watched for lecture.
Overall, I expect this compartment to flashover within minutes and all the contents to be
destroyed.
Heat transfer mechanisms include conduction, convection, and radiant heat. Conduction
is where heat is transferred from a warmer object through touch, for example if the heater were
to be contacting the couch or the blanket the heat would be transferred from the heater to
blank/couch by contact. Convection is essentially the phrase “hot air rises, cold air sinks.” The
heat created by the heater will rise and become cooler, causing it too then lower. This cycle
continues, and you have what are known as convection currents. Radiation heat transfer is where
an object within reasonable proximity to another object emitting heat will also become warmer.
For example, the heater is not contacting the couch or blanket, but they still become warmer due
to the heater releasing heat. Convection heat transfer is largely present during the fire growth
stage, while radiant heat transfer takes over in the flashover and post flashover stages (Gorbet et
al., 2016).
ANTICIPATED FIRE GROWTH
5
The thermal radiation given off the initial polyurethane foam fire will reach the ignition
temperature for a majority of the other fuel items as it grows and spreads. Thus, causing a
simultaneous ignition of other fuels in the compartment. Temperatures within the compartment
during a flashover can reach from approximately 593°C to 649°C, and post flashover
temperatures can reach up to 1093°C. Heat flux for the onset of a flashover is 20 kW/m
2
at floor
level. The heat flux post flashover is 200 kW/m2 (FEMA, 2016). Compartment fires are known
to flashover due to the sufficient fuels and inadequate oxygen/ventilation in the confined space.
The lack of oxygen is why flashovers have flames bellowing out of ventilation areas as the fire
transitions from a fuel-controlled fire to a ventilation-controlled fire, there is simply too much
fuel and not enough oxygen.
ANTICIPATED FIRE GROWTH
6
References
FXI. (2014).
Safety Data Sheet - qckslvr.com
.
https://www.qckslvr.com/Images/quicksilveranalytics/sds/_C__BIS-
4001A_BISKIT_SDS.pdf. Retrieved May 6, 2022, from
https://www.qckslvr.com/Images/quicksilveranalytics/sds/_C__BIS-
4001A_BISKIT_SDS.pdf
Gorbett, G. E., Pharr, J. L., & Rockwell, S. R. (2016).
Fire dynamics
(Second). Pearson.
FEMA. (2016). Fire Investigation: Fire Dynamics and Modeling. Nfa.usfa.fema.gov. Retrieved 7
May 2022, from https://nfa.usfa.fema.gov/ax/sm/sm_r0204.pdf.
Solids - densities
. Engineering ToolBox. (n.d.). Retrieved May 2, 2022, from
https://www.engineeringtoolbox.com/density-solids-d_1265.html
U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington. (2004,
December).
Nuclear regulatory commission
. Retrieved May 2, 2022, from
https://www.nrc.gov/docs/ML0432/ML043290075.pdf
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help