Transcript FIRE SPREAD IN BUILDINGS URBAN FIRE FORUM Robert James Regulatory Services May 23, 2012 © 2011 Underwriters Laboratories Inc.

FIRE SPREAD IN BUILDINGS URBAN FIRE FORUM
Robert James
Regulatory Services
May 23, 2012
© 2011 Underwriters Laboratories Inc.
Size Up and Tactics
???
Design of Newer Homes
Larger Homes
Average Square Footage of New Single-Family
Homes
2,700
26% of Houses
built in 2008
were greater
than 3000 ft2
2,500
2,300
2,100
1,900
1,700
1,500
1972
1978
1984
1990
1996
2002
2008
Source: http://www.census.gov
Larger Homes
Percent of Total
Number of Home Levels
100
90
80
70
60
50
40
30
20
10
0
1970
1-Story
2-Story
1980
1990
2000
2010
Source: http://www.census.gov
Open Spaces
Open Spaces
Open Floor Plans
Great Rooms
9-14 ft Ceilings
Open Foyers
All of these features add volume/air which allows the fire to
grow and smoke to spread.
Increased Fuel Loads
• Upholstered furniture such as
chairs, recliners, love seats and sofas are
common fuel packages in the living room
or family room of a residential occupancy.
• A single upholstered chair can provide
enough energy to take a 10′ x 12′ room to
flashover.
• A sofa can provide 3X the energy of a
single chair.
Increased Fuel Loads - Experiment
Modern Room
Legacy Room
Increased Fuel Loads - Experiment
Modern Room
Legacy Room
11
Increased Fuel Loads - Occupants
Times to escape safely have been
reduced greatly.
• NIST Study “Escape times in this study were
systematically shorter than those found in a similar
study conducted in the 1970's. “
• This is due mainly to faster fire development times due
to modern furniture.
• Standards to improve the fire hazard posed by
furniture are not widely adopted in the US. Mattresses
are an exception to this post 2005.
Increased Fuel Loads – Fire fighters
Legacy
Modern
Changing Building Materials - Linings
• The wall lining can play
an important roll in the
transition from a room
fire to a structure fire.
• Fire training buildings
are constructed with
concrete walls so that
they can have repeated
fires.
Open Void Spaces – Attic Voids
If you can think it – it can be designed.
House geometries are limitless.
Changing Building Materials - Doors
• Interior doors have been made
lighter and use less material.
• If a fire in a closed room does not
run out of air and extinguish; then
it can burn through a door and
extend to the rest of the house.
• Many new doors are hollow and
filled with cardboard spacers or
are molded of wood particles
Changing Building Materials - Windows
• Windows have become more
energy efficient by adding glazing
and coatings.
• The easier windows fail due to
heat exposure the more air
available to feed a fire. The other
changes such as to the fuel load
make this important.
Current UL research project aims
to examine this with DHS AFG
funding.
Changing Building Materials
Home Sheathing: Solid Boards → Plywood → OSB →
Asphalt Fiberboard → Cardboard
Wall Linings: Plaster and lath → Gypsum Board
Structural Components:
Old Growth Lumber → New Growth Lumber
→ Engineered Lumber
Windows: Single Glazed → Double Glazed → Wood Framed
→ Vinyl Framed
Doors: Solid Core → Hollow Core → Composite Doors
Evolutions in building materials create changes in the fire environment.
How all of these changes compound is not well understood.
Changing Building Materials - Sheathing
Recently, serious fires in the
US have been the result of
fires starting on the outside of
the structure and spreading to
the inside.
Virginia – 1FF LODD
Loudon County, VA – May 25th 2008 – 1FF LODD
Changing Building Materials - Sheathing
Sources/Causes:
• Another structure
• Smoking materials
• Mulch
• Grilling
• Others
Structural Stability of Engineered Lumber in
Fire Conditions
21
Different Modern Construction Components
Time/Temperature Curve
2000°F
4 HR
2000
1700°F
1 HR
1800
1600
1400
1200
1000
1000°F
5 MIN
800
600
400
200
0
1
2
3
4
Modern Construction Unprotected 12” I Floor Joist
Large percentage of floor is detached from test frame
After
Before
Modern Construction Unprotected 12” I-Joist
Test Assembly # 2 Post Photos Collapse Time = 6:00 (ISO 4:00)
Legacy Construction Unprotected 2 x 10 Floor Joist
Post Photos Collapse Time = 18:45
Assembly
Structural Element
Type
Ceiling
Finish
Rating
(min : sec)
Protective
Membrane
Breach
Allowable
Deflection
L/240 = ¾”
(min : sec)
Fire Fighter
Breach (min
: sec)
1
2x10 Joist Floor
Legacy
None
0:45
0:00
3:30
18:35
2
Wood I Joist Floor
Lightweight
None
0:30
0:00
3:15
6:00
8
2x10 Joist Floor
Legacy
Lath and plaster
74:001
741
75:45
79*
3
2x10 Joist Floor
Legacy
Regular gypsum
wallboard
15:30
23:30
35:30
44:40
4
Wood I Joist Floor
Lightweight
Regular gypsum
wallboard
7:45
17:45
3:30
26:43
5
Metal Gusset Truss
Floor
Lightweight
Regular gypsum
wallboard
10:45
16:30
20:45
29*
6
Finger Joint Truss
Floor
Lightweight
Regular gypsum
wallboard
12:15
16:00
24:00
26:30
7
2x6 Joist & Rafter
Roof
Legacy
Regular gypsum
wallboard
15:15
15:45
3
382
9
Metal Gusset Truss
Roof
Lightweight
Regular gypsum
wallboard
13:45
13:45
3
23:10
* - Denotes approximate time
1 - Denotes total failure of ceiling - plaster & lath had deflected down to & was supported by TC's prior to event
2 - Kneeling fire fighter fell over & flaming impacting on
3 - Denotes not applicable to roof structures
Experimental Pictures
31
Improving Fire Safety by Enhancing the Fire
Performance of Engineered Floor Systems and
Providing the Fire Service with
Information for Tactical Decision Making
32
Structural Beam Tests
33
Full-span field experiments
34
Full-span laboratory experiments
Experiment
1
Floor System
Wood I-Joist
2
3
Wood I-Joist
Parallel Chord Wood Truss
Description
Repeat of Field Experiment 3, Max
Ventilation
Max Ventilation, Torch Ignition
Gypsum ceiling, Void Ignition
4
Parallel Chord Wood Truss
Gypsum ceiling, 80 ft2 exposed
35
Experimental Pictures
36
Existing Structure Experiments
37
Modern Suppression
38
Fire Formula of Modern Homes
Larger Homes
Open Spaces
Inc. Fuel Loads
 Faster fire propagation
 Shorter time to
flashover
 Rapid changes in fire
dynamics
 Shorter escape times
Voids Spaces
Changing Bldg.
Materials
 Shorter time to collapse
39
DHS / Assistance to Firefighters grant – PV and
Fire Fighter Safety
The project that addresses fire fighter’s concerns
regarding fighting fires involving photovoltaic (PV)
modules.
The deployment of PV complicates traditional firefighter
suppression, ventilation and overhaul tactics - potentially
exposing firefighters to electrical hazards not
encountered with traditional utility power supplies.
•Shock Hazard Due to the Presence of Water and PV
Power During Suppression Activities
•Shock Hazard Due to the Direct Contact With Energized
Components During Firefighting Operations
•Emergency Disconnect and Disruption Techniques
• Severing of Conductors
• Assessment of PV Power During Low Ambient Light,
Artificial Light and Light from a Fire
• Assessment of Potential Shock Hazard From Damaged
PV Modules and Systems
Photos courtesy of College Park MD Fire Department
40
PV and Fire Fighter Safety Highlights – Power
Generation, Fireground Illumination
Experiments using ground lighting towers
indicate that artificial light at night (e.g. ground
scene lighting) can cause a typical rooftop PV
array to generate current at hazardous levels.
Current
(mA)
Hazard
Leakage
Safe
2
Perception
40
Lock On
240
Electrocution
1000 Volt Array with Night-Time Illumination from Fire Truck(s) Lighting
Truck #1
Truck #2
Total
Distance
Bed 12 kW
Bed 6 kW
Lighting
from
Boom 6 kW
Boom 4.5 kW
kW
Array (Feet)
None
Bed + Boom
Volts
MilliAmps
Hazard
48
0
Safe
18
25
812
132
Lock On
Bed + Boom
10.5
38
780
88
Lock On
Boom
4.5
38
738
50
Lock On
Bed + Boom
28.5
25 & 38
836
212
Lock On
Partial Bed
3
25
657
22
Perception
Partial Bed
1.5
25
575
11
Perception
Bed + Boom
18
50
735
37
Perception
Bed + Boom
10.5
75
700
22
Perception
Bed + Boom
28.5
50 & 75
773
49
Lock On
1.5
50
340
1.5
Safe
Bed + Boom
Bed + Boom
Partial Bed
41
PV and Fire Fighter Safety Highlights – Power
Generation, Fire Illumination
Using a stack of ignited wood skids to illuminate
a PV module resulted in surprising results of
hazardous power levels at various distances
from the fire.
Light from a Fire (Single Module)
Distance from
Open Circuit
Short Circuit
Fire (Feet)
Volts
MilliAmps
Hazard
75
30
52
Lock On
50
31
57
Lock On
40
32
59
Lock On
15
33
62
Lock On
Full Sun
37
7500
42
PV and Fire Fighter Safety Highlights –
Depowering by Shielding
Results indicate a range of effectiveness
between commercially available salvage
tarps and generic plastic sheet tarps
ranging from minimal voltage output to null
as compared to a baseline measurement.
Cost
Use of Various Tarps to Block Illumination
Open
Short
Circuit
Circuit
Tarp
Color Layers
Volts
Amps
Hazard
$15
$15
4.0 mil sheet
4.0 mil sheet
Black
Black
1
2
33
0.5
0
0
Safe
Safe
$16
$16
5.1 mil tarp
5.1 mil tarp
Dark Blue
Dark Blue
1
2
126
121
2.1
1
Electrocution
Electrocution
Salvage Canvas Dark Gray
1
3.2
0
Safe
1
124
1.8
Electrocution
148
8.1
$78
$94
Salvage Vinyl
Full Sun
Red
Photo above courtesy of San Jose Fire Department..
43
www.ul.com/fireservice
44
Impact of Ventilation on Fire Behavior in Legacy and
Contemporary Residential Construction
1200 ft2 One-Story House
3200 ft2 Two-Story House
45
UL Web Site:
www.ul.com
© 2011 Underwriters Laboratories Inc.
www.ul.com/fireservice
Fire Fighter Safety Projects
1) Impact of Ventilation on Fire Behavior in Legacy and
Contemporary Residential Construction (2008 DHS AFG)
2)
Structural Stability of Engineered Lumber in Fire Conditions
(2006 DHS AFG)
3) Improving Fire Safety by Enhancing the Fire Performance of
Engineered Floor Systems and Providing the Fire Service with
Information for Tactical Decision Making (2009 NIST ARRA)
48
THANK YOU.
Contact Information:
Bob James
Program Manager
[email protected]
813-956-8669
www.ul.com/fireservice