upholstered furniture flammability

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RESEARCH REPORT
UPHOLSTERED FURNITURE FLAMMABILITY
Thomas Fabian, Ph.D.
Fire Hazards Manager, Corporate Research
DISCLAIMER
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shall UL, its employees, or its agents incur any obligation or liability for damages including, but not limited to, consequential damage arising out
of or in connection with the use or inability to use the information contained in this Report. Information conveyed by this Report applies only to
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Report in no way implies Listing, Classification or Recognition by UL and does not authorize the use of UL Listing, Classification or
Recognition Marks or other reference to UL on or in connection with the product or system.
Issue date: July 31, 2013
Upholstered Furniture Flammability
P. ii
EXECUTIVE SUMMARY
Upholstered furniture was identified as a source of dangerous fire potential forty years ago in the
1973 report “America Burning” written by the National Commission on Fire Prevention and
Control.1 In the report smoking was identified as the predominant source of upholstered furniture
fires. Since then considerable attention has been given to reduce fires and associated losses
stemming from smoking related ignition sources including development of voluntary standards
and mandatory regulations, campaigns to curb smoking, and regulations and campaigns to
increase the presence of smoke alarms in households.
Between 1980 and 2009, residential structure fires originating with upholstered furniture
declined from 36,900 to 5,600.2 While the number of upholstered furniture fires has been
significantly reduced since 1980, they remain persistent and deadly. During the 2006 to 2010
time period these fires resulted in annual averages of 480 civilian deaths, 840 injuries, and more
than $427 million in direct property damage.3 The National Fire Protection Association (NFPA)
reported that “fires beginning with upholstered furniture accounted for 2% of reported home fires
but one of every five (19%) home fire deaths.”
Considerably less attention has been given to fires beginning from open flame ignition of
furniture. Small open flames such as candles, matches or lighters represent a different exposure
threat than smoldering induced by smoking materials or heating equipment. Upholstered
furniture fires started by small open flames are more likely to spread to the surrounding room
and residential structure than fires started by smoking materials.
During a home fire, upholstered furniture can become a significant fuel source. When exposed to
an open flame, this furniture can substantially contribute to a room’s time to flashover. Limiting
the fire growth from an upholstered furniture item can improve occupant safety and likelihood of
safely escaping.
UL, a leader in fire safety for over a century, initiated a self-funded exploration study in 2008 to
explore whether or not commercially available products such as flame retardant treated foams
and fire barriers (interliners) can retard and/or reduce the fire growth rate of upholstered furniture
exposed to small open flames. This study was an extension to what was learned for mattresses
(another significant source of fuel in a home fire) following the 2006 Consumer Product Safety
Commission’s Standard for the Flammability (Open Flame) for Mattress Sets 4.
Eleven commercially available barrier materials constituting different chemistries and physical
structures (including flat weaves, knits and high lofts); two comparable density polyurethane
foam materials, a non-flame retardant foam commonly used in upholstered furniture and a
1
“America Burning”, The Report of the National Commission on Fire Prevention and Control, US Fire
Administration, United States (May 4, 1973).
2
Ahrens, M. “Home Fire that Began with Upholstered Furniture”, National Fire Protection Association, United
States (2011).
3
Ahrens, M. “Home Structure Fires”, National Fire Protection Association, United States (2012).
4
16 CFR Part 1633 Standard for the Flammability (Open Flame) for Mattress Sets, U.S. Consumer Public Safety
Commission, United States. (March 15, 2006).
This Report cannot be modified or reproduced, in part, without the prior written permission of Underwriters Laboratories Inc.
Copyright © 2013 Underwriters Laboratories Inc.
P. iii
California Technical Bulletin (TB) 117 compliant fire-retardant treated foam; and the most
popular cover fabric from the largest upholstered furniture cover fabric supplier in the USA were
included in the investigation.
The investigation covered three scales of combustibility: (1) material-level experiments, (2)
mock-up experiments, and (3) full-size furniture experiments. The combustibility behavior of the
individual sample materials and combinations of materials (i.e. foam/barrier liner/cover fabric)
under well-ventilated, early stage flaming fire conditions was characterized using a cone
calorimeter. In the mock-up experiments, cushions of the foam and barrier liner combinations
evaluated in the material-level experiment phase were arranged to replicate an interior corner
such as that formed by the seat, back, and arm of a chair/sofa. The mock-up arrangements were
ignited at the interior intersection of the three cushions using a match-flame equivalent gas
burner. Heat release rate and mass loss rate were measured under an open calorimeter.
Combustibility of full-size chairs and sofas made from four of the foam and barrier liner
combinations was compared. Furniture pieces were ignited at a seat-back-arm interior corner,
center of the seat-back cushions, and the back leg area using the same match-flame equivalent
gas burner as for the mock-up assemblies. Heat release rate and mass loss rate were measured
under a product calorimeter.
While this investigation was by no means all encompassing, particularly with regards to the
flame retardant treated foam and the commercial applicability of the tested fire barrier and foam
materials, data from the cone calorimeter material-level, intermediate calorimeter mock-up, and
full-scale furniture testing indicate the following:

The three investigated general fire mitigation approaches for upholstered furniture
(substitution of foam without fire retardants with flame retardant treated foam, substitution of
polyester wrap with high-loft fire barrier, and inclusion of a flat fire barrier between the
cover fabric and polyester wrap) demonstrated some degree of reduction in ignitability and/or
flammability.

A layer of smooth bond polyester wrap (used to “soften” cushion edges) was sufficient to
make the investigated fire-retardant treated foam indistinguishable from the untreated foam.

Fire barrier technology, i.e. material chemistry and physical form, played a significant role
on ignitability and combustibility; however, all of the sample combinations incorporating the
fire barriers exhibited greater fire resistance than the polyester wrapped polyurethane foam
cushion with or without flame retardant.

Fire barriers were more effective retarding fire growth than the flame retardant treated foam
meeting the minimum performance requirements specified in TB 117. It should be noted that
TB 117 only prescribes a minimum performance level and that other compliant foam
products utilizing different flame retardant chemistries and/or concentrations may yield more
significant results.

Inclusion of an investigated fire barrier significantly retarded self-sustained flaming and fire
growth rate in upholstered chairs. This slower growth rate could delay or even prevent room
flashover thereby potentially reducing occupant deaths and injuries and property damage.

Poor seam construction can compromise the effectiveness of fire barriers.
P. iv
ADDITIONAL INFORMATION
Supplemental to the research presented herein, a series of living room fires and house fires were
conducted to better illustrate the impact upholstered furniture materials play on fire growth and
subsequent occupant tenability and survivability. These experiments were limited to a few
combinations of materials. An overview can be found at www.ul.com.
RECOMMENDATIONS FOR FUTURE RESEARCH
Based upon the results of this Project, the following were identified as areas that would benefit
from further research:
 Assessment of new fire barriers not available at the time of this investigation
 Broader study of flame retardant treated foams with regards to flame retardant chemistry and
concentration effects on upholstered furniture flammability
 Impact of filling materials other than polyurethane foam on upholstered furniture
flammability
 Combinations of flame retardant treated foam, other filling materials, and barriers
 Smoldering ignition resistance of fire barrier clad upholstered furniture
 Further refinement of small-scale predictive flammability test methods
 Assessment of furniture geometry impact on upholstered furniture flammability
 Impact of aging and use on the flammability of upholstered furniture constructed with fire
barriers and/or flame retardant-treated foams
 Impact of the slower fire growth rate in upholstered furniture on the time to room flashover
 Impact of the slower fire growth rate in upholstered furniture on occupant tenability and
survivability
P. v
TABLE OF CONTENTS
EXECUTIVE SUMMARY ............................................................................................................ ii
Additional information .............................................................................................................. iv
Recommendations for Future Research ..................................................................................... iv
LIST OF FIGURES ...................................................................................................................... vii
LIST OF TABLES ........................................................................................................................ xii
INTRODUCTION .......................................................................................................................... 1
FIRES ORIGINATING FROM SMOLDERING IGNITION SOURCES................................. 2
Fires Originating from Smoking Materials (small smoldering ignition source) ..................... 2
Fires Originating from Heating Equipment (large smoldering ignition source) ..................... 6
Fires Originating from Electrical Distribution and Light Sources .......................................... 6
FIRES ORIGINATING FROM OPEN FLAMES...................................................................... 6
PROJECT OBJECTIVE AND TECHNICAL PLAN................................................................... 11
OBJECTIVES ........................................................................................................................... 11
LIMITATIONS IN SCOPE ...................................................................................................... 11
TECHNICAL PLAN ................................................................................................................ 11
TASK 1 – SELECT AND PROCURE SAMPLE MATERIALS ................................................. 13
TASK 2 – CHARACTERIZATION OF SAMPLE MATERIALS .............................................. 17
EXPERIMENTAL .................................................................................................................... 17
Density .................................................................................................................................. 17
Thickness .............................................................................................................................. 17
Chemistry (FTIR) .................................................................................................................. 17
Elemental Analysis (ICP-MS) .............................................................................................. 17
Quantitative Elemental Analysis (Boron, Bromine and Chlorine) ....................................... 18
Pyrolysis-GC/MS (Py-GC/MS) ............................................................................................ 19
Thermal Degradation (TGA) ................................................................................................ 20
SEM-EDS ............................................................................................................................. 20
Potential Heat ........................................................................................................................ 20
Combustibility....................................................................................................................... 20
RESULTS ................................................................................................................................. 21
Density .................................................................................................................................. 21
Thickness .............................................................................................................................. 22
Chemistry (FTIR) .................................................................................................................. 22
Elemental Analysis (ICP-MS) .............................................................................................. 28
Quantitative Elemental Analysis (Boron, Bromine and Chlorine) ....................................... 30
Pyrolysis-GC/MS (Py-GC/MS) ............................................................................................ 30
Thermal Degradation (TGA) ................................................................................................ 31
SEM-EDS ............................................................................................................................. 41
Potential Heat ........................................................................................................................ 44
Combustibility....................................................................................................................... 44
SUMMARY .............................................................................................................................. 46
TASK 3 – MATERIAL COMBINATION COMBUSTIBILITY EXPERIMENTS .................... 48
SAMPLES ................................................................................................................................ 48
EXPERIMENTAL .................................................................................................................... 50
P. vi
RESULTS ................................................................................................................................. 51
Foam Thickness .................................................................................................................... 54
Polyester Wrap ...................................................................................................................... 54
Flame retardant Treated Foam .............................................................................................. 56
High-Loft Barriers ................................................................................................................ 58
Flat Barriers .......................................................................................................................... 61
ANALYSIS AND DISCUSSION ............................................................................................ 64
Influence of Cover Fabric ..................................................................................................... 64
Ignitability ............................................................................................................................. 66
Combustion Duration and Intensity ...................................................................................... 67
Correlation between Combustibility Results ........................................................................ 70
SUMMARY .............................................................................................................................. 72
TASK 4 – MOCK-UP ASSEMBLY COMBUSTIBILITY EXPERIMENTS ............................. 73
SAMPLES ................................................................................................................................ 73
EXPERIMENTAL .................................................................................................................... 74
RESULTS ................................................................................................................................. 76
Influence of Polyester Wrap ................................................................................................. 84
Influence of Flame retardant Treated Foam .......................................................................... 86
Influence of High-Loft Barriers ............................................................................................ 87
Influence of Flat Barriers ...................................................................................................... 90
ANALYSIS ............................................................................................................................... 94
Ignitability and Self-Sustained Combustion ......................................................................... 94
Combustion Duration and Intensity ...................................................................................... 95
SUMMARY .............................................................................................................................. 96
TASK 5 – FULL-SCALE FURNITURE COMBUSTIBILITY EXPERIMENTS ...................... 98
SAMPLES ................................................................................................................................ 98
EXPERIMENTAL .................................................................................................................. 101
RESULTS ............................................................................................................................... 101
ANALYSIS ............................................................................................................................. 109
Influence of Ignition Location ............................................................................................ 109
Influence of Furniture Component Materials ..................................................................... 113
Comparison of Full-scale Furniture Experiments to Mock-Up Assembly Experiments .... 115
SUMMARY ............................................................................................................................ 118
FINDINGS .................................................................................................................................. 120
IMPLICATIONS FOR POLICY AND PRACTICE .................................................................. 125
IMPLICATIONS FOR FUTURE RESEARCH ......................................................................... 125
FUNDING DISCLOSURE ......................................................................................................... 126
APPENDIX A: MOCK-UP ASSEMBLY TEST FRAME ......................................................... 127
APPENDIX B: FULL-SCALE FURNITURE HEAT RELEASE RATE AND MASS LOSS
PLOTS ........................................................................................................................................ 128
P. vii
LIST OF FIGURES
Figure 1: CPSC Cigarette Ignition Resistance Test (reprinted from 16 CFR Part 1634) ............... 3
Figure 2: Polyester microsuede cover fabric (C) .......................................................................... 14
Figure 3: Polyester wrap (W) ........................................................................................................ 14
Figure 4: Fire barrier 1 (FB1) ....................................................................................................... 14
Figure 5: Fire Barrier 2 (FB2) ....................................................................................................... 14
Figure 10: Fire Barrier 7 (FB7) ..................................................................................................... 15
Figure 13: Fire Barrier 10 (FB10) ................................................................................................. 15
Figure 14: Fire Barrier 11 (FB11) ................................................................................................. 16
Figure 15: ASTM E1354 Cone calorimeter sample holder .......................................................... 21
Figure 16: FTIR spectra for cover fabric C and polyester wrap W. ............................................. 23
Figure 17: FTIR spectra for PU and frPU foams. ......................................................................... 24
Figure 18: FTIR spectra for para-aramid flat fire barriers FB1 and FB2. .................................... 24
Figure 19: FTIR spectra for flat fire barrier FB3. ......................................................................... 25
Figure 20: FTIR spectra for elastic knit flat fire barriers FB4, FB5, and FB6. ............................ 25
Figure 21: FTIR spectra for cotton high-loft fire barrier FB7 and rayon high-loft fire barrier FB9.
..................................................................................................................................... 26
Figure 22: FTIR spectra for two-layer (cotton/rayon) high-loft fire barrier FB8. ........................ 26
Figure 23: FTIR spectra for three-layer (cotton/rayon/rayon) high-loft fire barrier FB10. .......... 27
Figure 24: FTIR spectra for high-loft fire barrier FB11. .............................................................. 27
Figure 25: FTIR spectra for decking D. ........................................................................................ 28
Figure 26: TGA results for cover fabric C. ................................................................................... 32
Figure 27: TGA results for polyurethane foam PU. ..................................................................... 33
Figure 28: TGA results for flame retardant treated polyurethane foam frPU. .............................. 33
Figure 29: TGA results for polyester wrap W. ............................................................................. 34
Figure 30: TGA results for para-aramid flat fire barrier FB1. ...................................................... 34
Figure 31: TGA results for para-aramid flat fire barrier FB2. ...................................................... 35
Figure 32: TGA results for flat fire barrier FB3. .......................................................................... 35
Figure 33: TGA results for elastic knit flat fire barrier FB4. ........................................................ 36
Figure 36: TGA results for cotton high-loft fire barrier FB7........................................................ 37
Figure 37: TGA results for rayon layer of two-layer high-loft fire barrier FB8. .......................... 38
Figure 38: TGA results for cotton layer of two-layer high-loft fire barrier FB8. ......................... 38
Figure 39: TGA results for rayon high-loft fire barrier FB9. ....................................................... 39
Figure 40: TGA results for rayon layer of three-layer high-loft fire barrier FB10. ...................... 39
Figure 41: TGA results for cotton layer of three-layer high-loft fire barrier FB10. ..................... 40
Figure 42: TGA results for high-loft fire barrier FB11................................................................. 40
Figure 43: TGA results for decking D. ......................................................................................... 41
P. viii
Figure 44: Cone calorimeter measured heat release rate profiles for polyurethane (PU) foam. .. 45
Figure 45: Cone calorimeter measured heat release rate profiles for flame retardant treated
polyurethane (frPU) foam. .......................................................................................... 45
Figure 46: Cone calorimeter cover fabric cut layout (left) and sample (right). Dashed lines are
fold lines; cross-hatched regions are overlapping portions on the sample bottom. .... 50
Figure 47: Time to ignition (blue) and flame duration (red) for cone calorimeter samples. Error
bars are SD. ................................................................................................................. 52
Figure 48: Peak and 180 second average heat release rates for cone calorimeter samples. Error
bars are SD. ................................................................................................................. 53
Figure 49: Effective heat of combustion for cone calorimeter samples. Error bars are SD. ........ 53
Figure 50: Polyurethane foam thickness effect on cone calorimeter measured combustibility. .. 54
Figure 51: Polyester wrap effect on combustibility of 25 mm thick foam cone calorimeter
samples. ....................................................................................................................... 55
Figure 52: Polyester wrap effect on combustibility of 51 mm thick foam cone calorimeter
samples. ....................................................................................................................... 55
Figure 53: Polyester wrap effect on combustibility of 51 mm thick fire-retardant treated foam
cone calorimeter samples. ........................................................................................... 56
Figure 54: Comparison of cone calorimeter measured combustibility for 51 mm thick
polyurethane foam and fire-retardant treated foam samples....................................... 57
Figure 55: Comparison of cone calorimeter measured combustibility for polyester wrap covered
51 mm thick polyurethane foam and fire-retardant treated foam samples. ................ 57
polyurethane foam and high-loft fire barrier 7 covered foam samples. ...................... 58
polyurethane foam and high-loft fire barrier 10 covered foam samples. .................... 60
polyurethane foam and high-loft fire barrier 11 covered foam samples. .................... 60
polyurethane foam samples with and without flat fire barrier 1. ................................ 61
foam samples with and without flat fire barrier 4. Note reignition of two barrier clad
samples. ....................................................................................................................... 63
Figure 67: Comparison of cone calorimeter measured combustibility for PU foam samples with
and without cover fabric. ............................................................................................ 65
P. ix
Figure 68: Comparison of cone calorimeter measured combustibility for frPU foam samples with
and without cover fabric. ............................................................................................ 66
Figure 69: Inverse relationship between flame duration and peak heat release rate. Error bars are
SD. .............................................................................................................................. 69
Figure 70: Inverse relationship between peak heat release rate and ignition. Error bars are SD. 70
Figure 71: First order correlation between effective heat of combustion and weight loss for cone
calorimeter samples. Error bars are SD. ..................................................................... 71
Figure 72: Zero-intercept, third order correlation between effective heat of combustion and
weight loss for cone calorimeter samples. Error bars are SD. .................................... 71
Figure 73: Mock-up assembly cushion arrangement example on test frame................................ 73
Figure 74: Mock-up experiment set-up......................................................................................... 75
Figure 75: Mock-up assembly experiment sample ignition exposure sequence........................... 76
Figure 76: Examples of post-experiment mock-up assemblies exhibiting (L to R): rapid selfextinguishment, delayed self-extinguishment, and consumed. ................................... 77
Figure 77: Time lapse photographs of fire growth behavior in for 20 s ignition exposure of
sample combination PU-FB7-C. ................................................................................. 78
Figure 78: Time lapse photographs of fire growth behavior in for 60 s ignition exposure of
sample combination PU-FB10-C. ............................................................................... 79
Figure 79: Time lapse photographs of fire growth behavior for 60 s ignition exposure of sample
combination PU-W-FB1-C. ........................................................................................ 80
Figure 80: Time lapse photographs of fire propagation and seam penetration in sample
combination PU-W-FB1-C. ........................................................................................ 81
Figure 81: Peak heat release rate of mock-up assembly experiments. Error bars are SD for the
mean of repeated exposures. ....................................................................................... 83
Figure 82: Total heat release for mock-up assembly experiments. Error bars are SD for the mean
of repeated exposures. ................................................................................................. 83
Figure 83: Heat of combustion for mock-up assembly experiments. Error bars are SD for the
mean of repeated exposures. ....................................................................................... 84
Figure 84: Polyester wrap effect on heat release rate profiles for PU foam based mock-up
assemblies. .................................................................................................................. 85
Figure 85: Polyester wrap effect on heat release rate profiles for frPU foam based mock-up
assemblies. .................................................................................................................. 85
Figure 86: Comparison of heat release rates for polyurethane foam and fire-retardant treated
foam mock-up assemblies. .......................................................................................... 86
Figure 87: Comparison of heat release rates for polyester wrap covered polyurethane foam and
fire-retardant treated foam mock-up assemblies. ........................................................ 87
high-loft fire barrier 7 covered foam mock-up assemblies. ........................................ 88
high-loft fire barrier 10 covered foam mock-up assemblies. ...................................... 89
high-loft fire barrier 11 covered foam mock-up assemblies. ...................................... 90
P. x
Figure 93: Comparison of heat release rates for polyester wrap covered polyurethane foam
mock-up assemblies with and without flat fire barrier 1. ........................................... 91
Figure 99: Single seat upholstered chair frame............................................................................. 98
Figure 100: Furniture at different stages of construction.............................................................. 99
Figure 101: Ignition locations for furniture combustibility experiments of single seat upholstered
chairs. ........................................................................................................................ 101
Figure 102: Heat release rate profiles for upholstered chair fire experiments. ........................... 102
Figure 103: Mass loss profiles for upholstered chair fire experiments. ...................................... 103
Figure 104: Fire progression for chair exhibiting rapid development and high peak heat release
rate............................................................................................................................. 104
Figure 105: Fire progression for chair exhibiting delayed development and moderate peak heat
release rate. ............................................................................................................... 105
Figure 106: Fire progression for chair exhibiting limited burning. ............................................ 106
Figure 107: Furniture calorimeter peak heat release rates. ......................................................... 107
Figure 108: Fire growth rate for furniture calorimeter experiments. Measured peak heat release
rates (kW) are listed above the respective experiments. ........................................... 108
Figure 109: Weight loss rate for furniture calorimeter experiments........................................... 108
Figure 110: Heat release rate results for Chair 1 (baseline) ignited at in tested locations. ......... 110
Figure 111: Heat release rate results for ignition of Chair 2 (FR foam) in various locations. ... 111
Figure 112: Heat release rate results for ignition of Chair 3 (High-loft barrier clad foam) in
various locations. ...................................................................................................... 111
Figure 113: Heat release rate results for ignition of Chair 4 (Full barrier clad) in various
locations. ................................................................................................................... 112
Figure 114: Heat release rate profiles for the four chair styles ignited at the back bottom. ....... 114
Figure 115: Heat release rate profiles for the two barrier clad chair styles ignited at the interior
corner. ....................................................................................................................... 115
Figure 116: Heat release rates for PU-W-C chair (interior corner ignition) and mock-up
experiments. .............................................................................................................. 116
Figure 117: Heat release rates for frPU-W-C chair (interior corner ignition) and mock-up
experiments. .............................................................................................................. 116
Figure 118: Heat release rates for PU-FB8-C cushioned chairs (interior corner ignition) and
mock-up experiments. ............................................................................................... 117
Figure 119: Mock-up test frame. ................................................................................................ 127
Figure 120: Heat release rate and sample mass of Chair 1 ignited at the corner. ....................... 128
P. xi
Figure 124: Heat release rate and sample mass of Chair 1 ignited at the seat/back. .................. 130
Figure 128: Heat release rate and sample mass of Chair 1 ignited at the back bottom. ............. 132
P. xii
LIST OF TABLES
Table 1: Major Causes for Upholstered Furniture Fire (2005 – 2009) ........................................... 1
Table 2: Tests for Resistance to Cigarette Ignition for Upholstered Furniture and its Components
....................................................................................................................................... 2
Table 3: Upholstered Fires and Associated Deaths Stemming from Small Open flame and
Smoking Materials. ....................................................................................................... 7
Table 4: Small Open Flame Ignition Tests for Upholstered Furniture ........................................... 7
Table 5: Larger Open Flame Ignition Tests for Upholstered Furniture .......................................... 9
Table 6: List of evaluated material-level samples. ....................................................................... 13
Table 7: Area density of fabric and barrier materials (expressed as mean ±SD). ........................ 22
Table 8: Barrier material thickness (expressed as mean ±SD). .................................................... 22
Table 9: Semi-quantitative elemental analysis by ICP-MS. ......................................................... 29
Table 10: Quantitative elemental analysis results for flame retardant characteristic elements. ... 30
Table 11: SEM-EDS quantified elemental composition (weight fraction) of fabric, foam and
barrier materials. ......................................................................................................... 42
Table 12: SEM-EDS quantified elemental composition (atomic fraction) of fabric, foam and
barrier materials. ......................................................................................................... 43
Table 13: Potential heat of foams, fabric and barrier materials (expressed as mean ±SD). ......... 44
Table 14: Combustibility characteristics of foam materials (expressed as mean ±SD). .............. 44
Table 15: Material characteristics of cover fabric and decking. ................................................... 46
Table 16: Material characteristics of untreated and treated polyurethane foams (expressed as
mean ±SD). ................................................................................................................. 46
Table 17: Material characteristics of flat fire barriers (expressed as mean ±SD). ........................ 47
Table 18: Material characteristics of high-loft fire barriers and polyester wrap (expressed as
mean ±SD). ................................................................................................................. 47
Table 19: Component experiment samples for cone calorimeter combustibility measurement. .. 49
Table 20: Ignition behavior of cone calorimeter component arrangements. ................................ 51
Table 21: Burning characteristics of cone calorimeter component arrangements (expressed as
mean ±SD). ................................................................................................................. 52
Table 22: Combustibility characteristics of foams with and without cover fabric (expressed as
mean ±SD). ................................................................................................................. 64
Table 23: Mock-up assembly experiment sample descriptions. ................................................... 74
Table 24: Mock-up assembly experiment results. ........................................................................ 82
Table 25: Single seat upholstered chair experiment sample descriptions................................... 100
Table 26: Single seat upholstered chair experiment sample mass. ............................................. 100
Table 27: Furniture combustion conditions at peak heat release rate. ........................................ 107
Table 28: Average peak heat release rate and standard deviation for each chair type ............... 112
P. 1
INTRODUCTION
For more than 20 years, upholstered furniture and mattresses/bedding fires have resulted in more
residential fire deaths than any other item.5 In 2006, the Consumer Product Safety Commission
(CPSC) developed and implemented the Standard for the Flammability (Open Flame) for
Mattress Sets 6 to address the fire performance of mattresses when exposed to open flame
ignition sources. The criteria for compliance set in the standard were feasible in part due to
innovations in thermal barrier (interliner) technology. The set of experiments described in this
report were conducted to explore whether or not the same mitigation approach can be effective
for upholstered furniture, for the purpose of reducing the flammability of upholstered furniture
and the deaths, injuries, and property losses due to upholstered furniture fires.
Between 1980 and 2009, residential structure fires originating with upholstered furniture
declined from 36,900 to 5,600. 7 While the number of upholstered furniture fires has been
significantly reduced since 1980, they remain persistent and deadly. During the 2006 to 2010
time period these fires resulted in annual averages of 480 civilian deaths, 840 injuries, and more
than $427 million in direct property damage.4 The National Fire Protection Association (NFPA)
reported that “fires beginning with upholstered furniture accounted for 2% of reported home fires
but one of every five (19%) home fire deaths.”
Table 1 lists the major causes of upholstered furniture fires between 2005 and 2009.6
Table 1: Major Causes for Upholstered Furniture Fire (2005 – 2009)
Ignition Source
Smoking materials
Intentional
Candle
Hot ember or ash
Heating equipment
Electrical distribution or light source
Playing with heat source
% Fires
28
13
10
10
9
9
8
% Deaths
58
6
6
7
7
11
5
% Injuries
38
8
12
10
6
10
9
In approximately 76% of upholstered furniture fires, the fire growth extended beyond the
upholstered furniture resulting in 94% of the total upholstered furniture fire fatalities.
Fires originating with upholstered furniture can be categorized into three general classes:
1. Small smoldering ignition source such as a cigarette, cigar or other smoking material
2. Large smoldering ignition source such as a portable heater
3. Small open flame ignition source such as a candle, match, or lighter
5
Ahrens, M. “Home Structure Fires”, National Fire Protection Association, United States (2012).
16 CFR Part 1633 Standard for the Flammability (Open Flame) for Mattress Sets, U.S. Consumer Public Safety
Commission, United States. (March 15, 2006).
7
States (2011).
6
P. 2
FIRES ORIGINATING FROM SMOLDERING IGNITION SOURCES
Fires Originating from Smoking Materials (small smoldering ignition source)
Smoking materials still represent the largest percentage of ignition sources for fires and related
deaths and injuries. Most of these fires are started by either discarded cigarettes or cigarettes in
close proximity of the upholstered furniture.
There are several standard test methods available that test the ignition resistance of upholstered
furniture components and products to cigarettes. These test methods are summarized in Table 2.
Table 2: Tests for Resistance to Cigarette Ignition for Upholstered Furniture and its Components
Test Method
8
CA TB 116
9
CA TB 117
10111213141516
UFAC
17
NFPA 260 ,
18
ASTM E 1353
19
16 CFR Part 1634
20
NFPA 261 ,
21
ASTM E 1352
22
BS 5852
23
EN 1021
Sample
Large scale mock-up or commercially available furniture
Small scale mock-up
Small scale mock-up
Small scale mock-up
Small scale mock-up
Large scale mock-up
Small scale mock-up or commercially available furniture
8
California Technical Bulletin 116 Requirements, Test Procedure and Apparatus for Testing the Flame Retardance
of Upholstered Furniture, California Bureau of Home Furnishings and Thermal Insulation, United States (Jan.
1980).
9
of Resilient Filling Materials Used in Upholstered Furniture, California Bureau of Home Furnishings and Thermal
Insulation, United States (March 2000).
10
Fabric Classification Test Method, Upholstered Furniture Action Council, United States (1990)
11
Interior Fabrics Test Method, Upholstered Furniture Action Council, United States (1990)
12
Barrier Test Method, Upholstered Furniture Action Council, United States (1990)
13
Decking Material Test Method, Upholstered Furniture Action Council, United States (1990)
14
Filling/Padding Components Test Methods, Upholstered Furniture Action Council, United States (1990)
15
Decorative Trims Test Method, Upholstered Furniture Action Council, United States (1990)
16
Welt Cord Test Method, Upholstered Furniture Action Council, United States (1990)
17
NFPA 260 Standard Methods of Tests and Classification System for Cigarette Ignition Resistance of Components
of Upholstered Furniture, National Fire Protection Association, United States (2013).
18
ASTM E 1353 Standard Test Methods for Cigarette Ignition Resistance of Components of Upholstered Furniture,
ASTM International, United States (2008).
19
16 CFR Part 1634 Standard for the Flammability of Residential Upholstered Furniture; Proposed Rule, US
Consumer Product Safety Commission, United States (March 4, 2008).
20
NFPA 261 Standard Method of Test for Determining Resistance of Mock-Up Upholstered Furniture Material
Assemblies to Ignition by Smoldering Cigarettes, National Fire Protection Association, United States (2013).
21
ASTM E 1352 Standard Test Method for Cigarette Ignition Resistance of Mock-Up Upholstered Furniture
Assemblies, ASTM International, United States (2008).
22
BS 5852 Methods of Test for Assessment of the Ignitability of Upholstered Seating by Smouldering and Flaming
Ignition Sources, British Standards Institute, United Kingdom (2006).
23
EN 1021-1 Furniture - Assessment of the ignitability of upholstered furniture - Part 1: ignition source
smouldering cigarette, European Committee for Standardization, Belgium (2006).
P. 3
The samples in the test methods are broken down into three different size categories: small scale
mock-up, large scale mock-up, and commercially available furniture.
The small scale mock-up assembly cigarette resistance test methods (CA TB 117, UFAC test
methods, NFPA 260, ASTM E 1353, 16 CFR Part 1634, BS 5852, and EN 1021) are similar to
one another and consist of a foam and fabric combination to form a seat and back arrangement,
such as Figure 1. In the American test methods (CA TB 117, UFAC test methods, NFPA 260,
ASTM E 1353, and 16 CFR Part 1634) the frame holding the arrangement is wood, while in the
European test methods (BS 5852 and EN 1021) the frame is steel. In these tests, a cigarette is
placed on the cover fabric in the crevice formed at the intersection of the back and seat. In the
American test methods, the cigarette is also covered with a smoldering-prone fabric.
Performance is characterized by either char length or mass loss, and observation of transition
from smoldering to flaming combustion.
Figure 1: CPSC Cigarette Ignition Resistance Test (reprinted from 16 CFR Part 1634)
CA TB 117 also has provisions for evaluating the upholstered furniture filling material. Whether
a sample passes or fails is dependent on the char length and mass loss of the filling material. The
sample fails if the maximum char length is greater than 2 inches in any direction. It will also fail
if, in two or more of the samples, the remaining unburned sample is less than 80% of the original
weight.
The small scale mock-up test methods developed by the Upholstered Furniture Action Council
(UFAC), American Society of Testing and Materials (ASTM), and NFPA are nearly identical.
The test methods divide the performance of the samples into Class I or Class II. These test
methods include a test method to address each of the following components of upholstered
furniture: cover fabric, interior fabric, welt cord, filling/padding, decking material, and barrier
material. Class I components do not ignite during the test and char less than 38 mm to 51 mm in
the vertical direction (the char length requirements change depending on the component being
tested). Any samples that do not meet the Class I requirements are categorized as Class II.
P. 4
Similarly, the CPSC developed test method, 16 CFR Part 1634, consists of a small-scale
arrangement and is shown in Figure 1. Compliant designs are also divided into two categories –
Type I and Type II. Type I upholstered furniture are finished articles constructed with cover
fabrics or other covering materials that are smolder-resistant in accordance with the cover fabric
performance test (Section 1634.4). Type II upholstered furniture are finished articles constructed
with internal barriers (placed between cover fabrics and any interior filling materials) that are
smolder and open flame-resistant in accordance with two barrier performance tests (Sections
1634.5 and 1634.6).
Type I compliance testing is conducted on mock-up arrangements of the standard polyurethane
foam (SPUF) substrate covered with the upholstery cover fabric under investigation. Compliance
is demonstrated if:
a) mock-up self-extinguishes within the 45 minute test period,
b) there is no transition to flaming combustion during the test period, and
c) mass loss of the SPUF substrate shall not exceed 10%.
Type I furniture may be constructed with any interior filling materials and no upholstery
materials other than cover fabrics need be qualified. Articles of upholstered furniture with noncomplying cover fabrics are required to have Type II barriers.
Type II compliance testing is conducted on mock-up arrangements of the internal fire barrier
under investigation placed between the standard polyurethane foam (SPUF) and a standard cover
fabric. Compliance is demonstrated if:
a) there is no transition to flaming combustion during the test period for the smoldering test
scenario mock-up (Section 1634.5),
b) mass loss of the SPUF substrate for the smoldering test scenario mock-up (Section 1634.5)
does not exceed 1%, and
c) total mass loss of the flaming test scenario mock-up (Section 1634.6) does not exceed 20%.
Type II furniture may be constructed with any cover fabrics and any interior fillings and no
upholstery materials other than barriers need be qualified.
Unlike the previously mentioned test methods, the British Standard (BS) 5852 addresses the
flammability of the combined material components of upholstered furniture in a small scale
mock-up, instead of a test method for each component incorporated in a standardized small scale
mockup. In this test method, the sample’s performance is determined by if and when the sample
ignites, and if it ignites, whether or not it is flaming ignition or progressive smoldering. BS 5852
defines progressive smoldering as:
a) “any test specimen that displays escalating smoldering combustion behavior so that it is
unsafe to continue the test and forcible extinction is required
b) any test specimen that smolders to the full thickness of the test specimen, or to more than 50
mm from the nearest part of the cigarette, within 60 min of placement of the cigarette
c) any test specimen that produces externally detectable amounts of smoke, heat or glowing 60
min after placement of the cigarette…
d) any test specimen that, on final examination, shows evidence of charring within the filling
(other than discoloration) more than 100 mm in any direction, apart from upwards, from the
nearest part of the original position of the source”
P. 5
The standard defines flaming ignition as:
a) “any test specimen that displays escalating flaming combustion behavior so that it is unsafe
to continue and forcible extinction is required
b) any test specimen that burns until it is essentially consumed within the test duration
c) any test specimen on which any flame front reaches the extremities of the specimen other
than the top of the vertical part of the test specimen or passes through the full thickness of the
test specimen within the duration of the test
d) the occurrence of any visible flaming within 60 min of placement of the cigarette…
e) any test specimen from which debris causes an isolated floor fire not meeting the
requirements of (the previous) item”
In European Standard EN 1021, the test method is similar. The most significant difference is the
definition of progressive smoldering and flaming ignition. In this standard progressive ignition is
defined as:
a) “any test assembly that displays escalating combustion behaviour so that it is unsafe to
continue the test and active extinction is necessary;
b) any test assembly that smoulders until it is largely consumed within the test duration;
c) any test assembly that smoulders to the extremities of the specimen, viz. upper or lower
margins, either side or to its full thickness, within the duration of the test;
d) any test assembly that smoulders after one hour from the beginning of the test;
e) any test assembly that, on final examination, shows evidence of active smouldering”
In EN 1021, flaming ignition is the presence of any flame.
In addition to small scale mock-up tests, there are large scale mock-up and commercially
available furniture tests. Large scale mock-ups consist of the upholstered furniture components
being arranged to resembled furniture of parts of furniture. The samples can consist of the
materials arranged and sized to simulate an arm and part of the back and seat of a sofa, for
example. In all of the following test methods the material components are evaluated together in
one sample. CA TB 116, NFPA 261, ASTM E 1352, and BS 5852 address large scale mock-ups
and/or commercially available furniture. In each of the standards, multiple burning cigarettes are
applied to the horizontal surfaces, crevices, edges, and any depressions that might exist in the
materials of the mock-up or furniture.
CA TB 116 includes multiple tests addressing the smooth surfaces, decking, welts, quilted
locations, tufted locations, crevices, tops of the arms and back, and covering materials of the
sample. In each, three burning cigarettes are applied to the area. The sample fails if it begins to
flame or char more than two inches in any direction.
NFPA 261 and ASTM E 1352 differ from CA TB 116 in that the burning cigarettes are placed on
similar areas of concern on one test sample during one test instead of multiple tests and samples.
In NFPA 261 and ASTM E 1352, the standards require reporting of the maximum char distance
and when ignition occurs at each location.
In BS 5852, only three locations are tested: one on the seat and two on the floor – one underneath
the furniture and one on the side of the furniture. The reporting for the commercially available
furniture test method within BS 5852 is almost the same as the small scale mock-up, described
P. 6
earlier. The definition for flaming ignition also includes “any test specimen on which any flame
front reaches the extremities of the specimen other than the top of the vertical part of the test
specimen, within the duration of the test.”
Fires Originating from Heating Equipment (large smoldering ignition source)
NFPA analysis of fires in home structure shows that portable and fixed heating equipment
including wood stoves were responsible for 8% of the fires and 7% of associated fatalities
involving the upholstered furniture as the first item ignited.24 It is conjectured that these fires
may occur when the upholstered furniture is in close proximity to the heating unit.
Currently, there are no standard tests for upholstered furniture that use radiant heating as the
ignition source. However, ASTM E 1354 Standard Test Method for Heat and Visible Smoke
Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter 25 offers a
potential small-scale test method to evaluate fabric and foam combinations exposed to radiant
heat in a manner similar to the conditions that may be encountered by heating equipment placed
close to an upholstered furniture item.
Fires Originating from Electrical Distribution and Light Sources
NFPA analysis of fires in home structure shows that electrical malfunction was a factor in an
annual average of 630 fires originating from upholstered furniture.26 Of these, lamps and lighting
equipment were involved in an average of 200 fires and 20 deaths per year, cords and plugs in
160 fires and 40 deaths, and wiring, switches, and outlets in another 240 fires.
In most cases involving wiring and cords, fires start when localized arcing and overheating occur
in damaged wiring. In cases involving lamps, a potential scenario is the close proximity of the
lamp to the upholstered furniture causing localized heating of the furniture fabric and ignition.
While there are no standardized tests representing electrical fires used to test upholstered
furniture, the open flame source may be able to represent a fire started with localized arcing and
overheating. Fires resulting from close proximity to lamps may be represented by radiant heating
provided by the Cone Calorimeter (ASTM E 1354).
FIRES ORIGINATING FROM OPEN FLAMES
Small open flames such as candles, matches or lighters represent a different exposure threat than
smoldering induced by smoking materials or heating equipment. Upholstered furniture fires
started by small open flames are less likely to be confined to the object of origin or room of
origin than fires started by smoking materials, Table 3 (note that smoldering fires must transition
to open flame fires in order to spread beyond the object of origin). It is also important to note that
when the small open flame induced fire was confined to the upholstered furniture item, there
24
States (2011).
25
ASTM E 1354 Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products
Using an Oxygen Consumption Calorimeter, ASTM International, United States (2013).
26
States (2011).
P. 7
were no fatalities reported. This suggests that limiting the fire growth from an upholstered
furniture item can provide significantly improve safety.
Table 3: Upholstered Fires and Associated Deaths Stemming from Small Open flame and Smoking Materials.
% of Fires
Open
Smoking
Flame
Materials
24
32
35
32
10
10
28
23
3
3
Extent of Flame Damage
Confined to object of origin
Confined to room of origin
Confined to floor of origin
Confined to building of origin
Extending beyond building of origin
% of Deaths
Open
Smoking
Flame
Materials
0
10
17
25
27
16
47
45
9
3
There are several standard test methods available to determine the performance of upholstered
furniture components using a small open flame as an ignition source. These are summarized in
Table 4.
Table 4: Small Open Flame Ignition Tests for Upholstered Furniture
Source
Number
-
28
Gas flame
1
2
0.077
20
29
Gas Flame
1
2
0.077
15
CA TB 117
BS 5852
Energy
(KJ)
(kW)
1
0.046
Ignition
Type
Gas flame
Test Standard
EN 1021
27
Flame Duration
(s)
12
Sample
Small scale mock-up
Small scale mock-up or
commercially available
furniture
Small scale mock-up
California TB 117 is a component test for upholstered furniture filling materials. Depending
upon the form of the component material, it is evaluated as either an independent component
material or in a component mock-up with a standard cover fabric:
 Resilient cellular materials (e.g. foam) are tested by direct exposure to flame source for 12
seconds and the pass/fail criteria is char length, flame duration and glowing combustion
duration (Section A Part I)
 Resilient cellular materials used in shredded form are further tested in a “pillow”
configuration to an open flame exposure for up to 12 seconds and the pass/fail criteria is
mass loss (Section A Part II)
 Expanded polystyrene beads are directly exposed to a flame generated by methenamine
reagent tablet and the pass/fail criteria is mass loss (Section A Part III)
 Non-man-made fillings are directly exposed to flame source for 12 s, pass/fail criteria is char
length and flame duration (Section B Part I)
27
28
29
EN 1021-2 Furniture - Assessment of the ignitability of upholstered furniture - Part 2: ignition source match
flame equivalent, European Committee for Standardizations, Belgium (2006)


P. 8
Feathers and down are tested in a “pillow” configuration to an open flame exposure for up to
12 seconds and the pass/fail criteria is mass loss (Section B Part II)
Man-made fiber fillings are directly exposed to flame for 5 seconds and the pass/fail criteria
is burn duration (Section C)
Test method BS 5852 provides provisions for evaluating upholstered furniture component
materials in a composite, small scale mock-up arrangement (Section 4) or as full furniture pieces
(Section 5). The mock-up arrangement consists of vertically and horizontally oriented
components which comprise a single combination of covering fabric, fire barrier (if used), and
filling material as used in the upper 75 mm (3 in.) of the upholstery in the upholstered furniture.
Under the full-furniture provision, the furniture piece is evaluated to ignition exposures to both
the seating surface as well as from underneath. The pass/fail criteria is the same for the two
approaches - presence of flaming combustion more than 120 seconds after removal of the
ignition source flame and presence of heat, glowing, or smoke production more than 15 minutes
after removal of the ignition source flame. The ignition flame, Source 1, is similar in size to that
produced by a match or a cigarette lighter and is frequently referred to as “match-flame
equivalent”.
Test method EN 1021 is similar to the small scale mock-up used in BS 5852 exposed to a Source
1 flame. The duration of the flame exposure is 5 seconds less in EN 1021 than BS 5852. This test
method does not provide pass/fail criteria. It does, however, require whether or not the sample
ignited to be recorded and if it did ignite, when it ignited and whether or not it was progressive
smoldering or flaming ignition.
Progressive smoldering is defined by EN 1021 Part 2 as:
“a) any test assembly that displays escalating combustion behaviour so that it is unsafe to
continue and test and active extinction is necessary;
b) any test assembly that smoulders until it is largely consumed within the test duration;
c) any test assembly that smoulders to the extremities of the specimen, viz. upper or lower
margins, either side or to its full thickness, within the duration of the test;
d) any test assembly that smoulders after one hour from the beginning of the test;
e) any test assembly that, on final examination shows evidence of active smouldering.
Flaming ignition is defined by EN 1021 Part 2 as:
“a) any test assembly that displays escalating combustion behaviour so that it is unsafe to
continue the test and active extinction is necessary;
b) any test assembly that burns until it is essentially consumed within the test duration;
c) any test assembly on which any flame front reaches the lower margin, either side or passes
through its full thickness within the duration of the test;
d) any flaming which continues for more than 120 s after removal of the burner tube.”
There are also a number of standard test methods available to determine the performance of
upholstered furniture and its components using larger open flames, larger than candles, matches
or lighters. These are presented in Table 5.
P. 9
Table 5: Larger Open Flame Ignition Tests for Upholstered Furniture
Test Standard
CA TB 133
30
ASTM E 1537
32
NFPA 266
34
Source
Number
Flame Duration
(s)
Gas flame
-
1600
20
80
Gas flame
-
1600
20
80
Gas flame
Gas flame
Gas flame
Wood crib
Wood crib
Wood crib
Wood crib
3
2
3
4
5
6
7
42
11
42
142
285
1040
2110
0.602
0.275
0.602
1
1.9
2.6
6.4
70
40
70
Burn-out
Burn-out
Burn-out
Burn-out
31
16 CFR Part 1634
BS 5852
Energy
(KJ)
(kW)
Ignition
Type
33
Sample
Large scale mock-up or
furniture
Large scale mock-up or
furniture
Small scale mock-up
Small scale mock-up or
furniture
Test methods California TB 133, ASTM E 1537, and NFPA 266 are calorimeter tests using the
full furniture (a large scale mock-up furniture assembly or commercially available product) as
the test sample whereas in 16 CFR Part 1634 the test sample is a small scale mock-up. BS 5852
provides test methods for both full furniture and small scale mock-ups.
In California TB 133 the test sample is located in a 12 × 8 ft. room with one 2 × 7 ft. doorway
opening. ASTM E 1537 allows the test to be conducted with the test sample either in a room or
directly under a calorimeter. The NFPA 266 is a calorimeter test only. A full furniture item or
mock-up consisting of seat, back and side arm cushions may be used in the ASTM E 1537 and
NFPA 266 test methods. All the tests employ a 10 × 10 in. (250 × 250 mm) square burner placed
over the seat of the upholstered furniture or mock-up as an ignition source with a heat output of
approximately 20 kW.
These tests when conducted under the calorimeter permit measurement of heat release rates,
smoke release rates, and weight loss. Tests conducted in the room also permit measurement of
the temperature of the hot gas layer, smoke obscuration, and carbon monoxide gas concentration.
If the calorimeter is used in the test, the CAL TB 133 has fire performance requirements for
upholstered furniture with respect to (i) peak heat release rate (< 80 kW); (ii) total heat released
(< 25 MJ during the first 10 minutes); (iii) smoke opacity (< 75% in the room at 4 ft. height); and
(iv) carbon monoxide concentration (not greater than 1000 ppm for 5 minutes).
30
California Technical Bulletin 133 Flammability Test Procedure for Seating Furniture for Use in Public
Occupancies, California Bureau of Home Furnishings and Thermal Insulation, United States (Jan. 1991).
31
ASTM E 1537 Standard Test Method for Fire Testing of Upholstered Furniture, ASTM International, United
States (2013).
32
NFPA 266 Standard Method of Test for Fire Characteristics of Upholstered Furniture Exposed to Flaming
Ignition Source, National Fire Protection Association, United States (1998).
33
34
P. 10
If the calorimeter is not used in the test, the CAL TB 133 has fire performance requirements with
respect to (i) peak temperature at the ceiling (< 200 °F); peak temperature at 4 ft. level (< 50 °F);
smoke opacity (< 75 % in the room at 4 ft. height); (iv) carbon monoxide concentration (not
greater than 1000 ppm for 5 minutes); and sample weight loss (< 3 pounds during the first 10
minutes of burning).
The requirements with and without the calorimeter measurements are similar, as relationships
between heat release rate and temperature have been established by McCaffrey et. al.35. The
weight loss and total heat generated requirements are also related through the heat of combustion
of the polyurethane foam (18 kJ/g) that is a key combustible component of the upholstered
furniture
BS 5852 evaluations of upholstered furniture component materials (Section 4) and full-furniture
pieces (Section 5) using the increasingly larger flame sources are conducted the same as with the
small flame source (Source 1). The pass/fail criteria for the two larger gas flame sources (2 and
3) are the same as for Source 1 – presence of flaming combustion more than 120 seconds after
removal of the ignition source flame and presence of heat, glowing, or smoke production more
than 15 minutes after removal of the ignition source flame. The pass/fail criteria for wood crib
sources is presence of heat, glowing, or smoke production more than 60 minutes after ignition of
the wood crib and the presence of flaming combustion more than 10 minutes after ignition of
wood crib Sources 4 and 5 or 13 minutes for wood crib Sources 6 and 7. The longer acceptable
flaming combustion durations for the wood crib sources are essentially two minutes longer than
the time necessary for the cribs to be consumed. Should the sample burn to an extremity other
than the top of the vertical part, it is considered a failure.
The proposed CPSC open flame ignition test (16 CFR Part 1634, Section 1634.6) is used when
the sample fails the cigarette ignition resistance test. The open flame ignition test uses a similar
test method to the component mock-up test method in BS 5852 with the Source 3 flame. In the
proposed CPSC test method, the “mockup must not exceed 20% mass loss by the end of the 45
minute test. 10 initial samples are tested. If there is a failure with any of the 10 specimens, an
additional 20 specimens are tested, and at least 25 of the 30 must meet the criteria for the sample
barrier to pass.”36
35
McCaffrey, B.J., Quintiere, J.G., and Harkleroad, M.F. “Estimating Room Temperatures and the Likelihood of
Flashover Using Fire Test Data Correlations”, Fire Tech, pp. 99-119 (1981).
36
P. 11
PROJECT OBJECTIVE AND TECHNICAL PLAN
The investigation focused on exploring whether commercially available flame retardant treated
foam and fire barrier technologies can retard and/or reduce the fire growth rate of upholstered
furniture when exposed to small open flames.
OBJECTIVES
The objectives of this study were to:
1. Explore strategies for the improvement of the fire performance of upholstered furniture with
respect to small open flame ignition sources.
2. Determine the influence of location of ignition on fire growth of full furniture chairs
3. Investigate the effect of sample size on fire growth
The objectives were accomplished through the following technical plan.
LIMITATIONS IN SCOPE
This study was focused on the flammability performance of materials and components used in
upholstered furniture. Flame retardant chemistry and concentration effects on flammability
performance were limited to the investigated materials. The study did not cover:
 Effectiveness of the fire mitigation approaches on occupant safety and egress
 Furniture comfort, durability and wear performance, and aesthetics
 Furniture construction practicality and affordability
Information conveyed by this report applies only to the specimens actually involved in these
experiments. The results may not be fully representative of all furniture constructions available
in the marketplace today. Thus, results should not be extrapolated to furniture comprised of
different materials, component arrangements, design geometry and features.
TECHNICAL PLAN
The technical plan consisted of six tasks that are summarized below.
Task 1 – Select and Procure Sample Materials
In this task, commercially available component materials intended for use in upholstered
furniture were selected and procured. Component materials included a cover fabric, polyurethane
foams with and without flame retardant treatment, and various fire barriers based upon their
chemical and physical attributes.
Task 2 – Characterization of Sample Materials
The selected sample materials were characterized for density, chemistry, thermal degradation
behavior, and combustibility. Compliance of the foams and cover fabric to appropriate
residential upholstered furniture standards was also verified.
Task 3 – Material Combination Combustibility Experiments
The combustibility of various combinations of foam, polyester wrap, barrier material and cover
fabric as would be used in upholstered furniture construction practice was characterized under
flaming conditions by oxygen consumption calorimetry (cone calorimeter) to assess materiallevel performance differences.
P. 12
Task 4 – Mock-Up Assembly Combustibility Experiments
In this task, different strategies for reducing and/or retarding fire growth were evaluated against a
baseline scenario to determine if commercially available products (e.g. FR foams, fire barriers)
can retard and reduce the fire growth rate in mock-ups exposed to an open flame ignition source.
Task 5 – Full-Scale Furniture Combustibility Experiments
The combustibility of single seat upholstered chairs exposed to an open flame ignition source
was characterized to assess system level performance of full-scale furniture. Chairs were
constructed using four different combinations of foam, polyester wrap, fire barrier material, and
cover fabric evaluated in Task 4.
Task 6 – Develop Technical Report
A comprehensive technical report was developed to summarize the details of the materials,
experiment samples and procedures, and the results obtained. The report also provides
recommendations for future study.
The results of this investigation (Task 6) are described herein.
P. 13
TASK 1 – SELECT AND PROCURE SAMPLE MATERIALS
Commercially available cover fabric, foams, and fire barriers representative of those prevalently
used in residential upholstered furniture and mattresses were selected for this study. The cover
fabric selected was the most popular cover fabric from the largest upholstered furniture cover
fabric supplier in the United States. The polyurethane foam was selected based on most
commonly used density in upholstered furniture37, use for compliance testing residential
sprinklers (UL 162638), and potential use for compliance testing smoke detectors and alarms (UL
21739 and UL 26840). Two versions of the foam were included in the study – a California
Technical Bulletin 117 (TB 117)41 compliant foam and a flame retardant free foam as specified
for residential sprinkler and smoke detector and alarm testing. Eleven different barrier products
were selected from a list of barrier products recommended by barrier manufacturers for use in
upholstered furniture. Selection of these barriers was based on their chemical and physical
attributes as well as prevalence in the market.
The purchased materials are identified and described in Table 6. Photographs of the cover fabric,
decking, polyester wrap, and fire barriers follow in Figure 2 through Figure 14.
Table 6: List of evaluated material-level samples.
Material ID
C
D
PU
frPU
W
FB1
FB2
FB3
FB4
FB5
FB6
FB7
FB8
FB9
FB10
FB11
Material Description
Cover fabric: beige, polyester microsuede
Decking: beige cotton twill (nominal 8 oz)
Polyurethane foam
Flame retardant treated polyurethane foam
Polyester wrap: 1 oz smooth bond
Fire barrier 1: Para-aramid-PET-Rayon blend nonwoven flat sheet
Fire barrier 2: Para-aramid blend nonwoven flat sheet
Fire barrier 3: Woven flat sheet
2
Fire barrier 4: Elastic knit flat sheet (nominal 5.5 oz/y )
2
2
2
Fire barrier 7: Cotton based high-loft (nominal 1.0 oz/y )
2
Fire barrier 8: Two layer (rayon/cotton) high-loft (nominal 0.75 oz/y )
2
Fire barrier 9: Rayon based high-loft (nominal 1.0 oz/y )
2
Fire barrier 10: Three layer (rayon/rayon/cotton) high-loft (nominal 0.8 oz/y )
Fire barrier 11: Cotton-viscose rayon blend high-loft
37
Knudtson, L. “Smolder Testing Evaluation of Selected Cigarettes”, Presented at: ASTM E05.15 Furnishings and
Contents. Atlanta, Georgia, United States (December 5, 2012).
38
UL 1626 Residential Sprinklers for Fire-Protection Service, Underwriters Laboratories Inc., United States (2008).
39
UL 217 Single and Multiple Station Smoke Alarms, Underwriters Laboratories Inc., United States (2006).
40
UL 268 Smoke Detectors for Fire Alarm Systems, Underwriters Laboratories Inc., United States (2009).
41
P. 14
Figure 2: Polyester microsuede cover fabric (C)
Figure 3: Polyester wrap (W)
Figure 4: Fire barrier 1 (FB1)
Figure 5: Fire Barrier 2 (FB2)
P. 15
P. 16
P. 17
TASK 2 – CHARACTERIZATION OF SAMPLE MATERIALS
Acquired sample materials were characterized for physical, chemical, and thermal characteristics
by a variety of analytical techniques. Measure physical properties included thickness and
density; chemical composition was characterized by Fourier Transform Infrared Spectroscopy
(FTIR), elemental analysis (ICP-MS), and pyrolysis-GC-MS (Py-GC-MS); and thermal
characteristics included thermal degradation behavior, potential heat and combustibility.
The two foams, PU and frPU, were evaluated for compliance to California Technical Bulletin
117 (TB 117) by the California Bureau of Home Furnishings and Thermal Insulation (BHFTI)42.
The frPU foam was found to be compliant and the PU foam was found to be non-compliant.
EXPERIMENTAL
Density
Area density of the fabric, polyester wrap, and fire barriers was determined by averaging the 10
specimens per sample. Specimen measuring 50.8 × 50.8 mm (2.0 × 2.0 in.) were cut using die
avoiding the fabric selvage and weighed on an analytical balance with a sensitivity of 0.0001 g.
Volume density of the foams was determined from 100 × 100 × 51 mm (4.0 × 4.0 × 2.0 in.)
samples. Three specimen of each foam type were measured using a caliper with a sensitivity of
0.01 mm and an analytical balance with a sensitivity of 0.0001 g.
Thickness
The uncompressed thickness of fire high-loft barriers was determined with a sensitivity of 0.01
mm. Reported results are the average of 10 specimens per sample.
Flat barrier thickness was measured using a Federal Product Corp; Model d71 dial micrometer
(85 g force exerted over 31.7 mm2) with a sensitivity of 0.01 mm. Reported results are the
average of 10 specimens per sample.
Chemistry (FTIR)
Infrared spectral response of the materials was characterized in the solid-state using a Nicolet
Nexus 470 FTIR with a Golden Gate KRS-5 diamond ATR accessory. Samples were scanned
from 400 to 4000 cm-1 wavenumber at a 4 cm-1 resolution; 32 scans were averaged per recorded
spectra.
Elemental Analysis (ICP-MS)
Semi-quantitative analysis of the materials for elemental metals and some non-metals by
inductively coupled plasma-mass spectroscopy (ICP-MS). Testing was performed by Galbraith
42
California Bureau of Home Furnishings and Thermal Insulation, 4244 South Market Ct., Suite D, Sacramento, CA
95834, United States.
P. 18
Laboratories43 following procedure ME-31 (Semi-Quantitative Metals Screen by Mass
Spectrometry).
ICP-MS is a highly sensitive method for quantifying metals and some non-metals at ppm and
lower concentrations. The technique couples an ICP with a mass spectrometer. Prior to analysis,
approximately 0.5 g samples were acidified or digested using appropriate sample digestion
methods. The resulting aqueous sample solution was then introduced into a calibrated ICP
instrument where the liquid carrier was evaporated and any dissolved solids were atomized for
detection in a mass spectrometer. Concentration was determined by comparison of the mass-tocharge ratio of each element in the sample solution to the mass-to-charge ratio of the same
element in the calibration solution.
Materials were tested for (listed in order of elemental mass): Lithium, Beryllium, Boron,
Sodium, Magnesium, Aluminum, Phosphorus, Potassium, Calcium, Scandium, Titanium,
Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Gallium, Germanium,
Arsenic, Selenium, Rubidium, Strontium, Yttrium, Zirconium, Niobium, Molybdenum,
Ruthenium, Rhodium, Palladium, Cadmium, Indium, Tin, Antimony, Tellurium, Cesium,
Barium, Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Europium, Gadolinium,
Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Hafnium, Tantalum,
Tungsten, Rhenium, Iridium, Platinum, Gold, Thallium, Lead, Bismuth, Thorium, and Uranium.
Minimum detection limits for all elements was typically 2 ppm; minimum detection limits for
iron and gold analysis of some samples were 20 ppm. Measurement accuracy for the utilized
semi-quantitative method was ±50 %.
Quantitative Elemental Analysis (Boron, Bromine and Chlorine)
Materials that had cotton as a component (FB7-11) were further analyzed for quantitative
assessment of boron content by ICP-AES using simultaneous optical systems and axial or radial
viewing of the plasma. Testing was performed by Galbraith Laboratories44 following procedure
ME-70 (Inductively Coupled Plasma Atomic Emission Spectrometry).
Prior to analysis, approximately 100 mg samples were acidified or digested using appropriate
sample preparation method. The resulting solution was nebulized and the resulting aerosol was
transported to the plasma torch. Element-specific emission spectra were produced by radiofrequency inductively coupled plasma. The spectra were dispersed by a grating spectrometer, and
the intensities of the emission lines were monitored by photosensitive devices. Background
correction was required for trace element determination. Background were measured adjacent to
analyte lines on samples during analysis. The position selected for the background-intensity
measurement, on either or both sides of the analytical line, was determined by the complexity of
the spectrum adjacent to the analyte line. In one mode of analysis the position used was as free as
possible from spectral interference and reflected the same change in background intensity as
occurs at the analyte wavelength measured. Background correction was not required in cases of
43
44
Galbraith Laboratories Inc., PO Box 51610, Knoxville, TN 37950-1610, United States.
P. 19
line broadening where a background correction measurement would actually degrade the
analytical result. Measurement accuracy for the ME-70 quantitative method was ±10 %.
The foam and fire barrier materials were further analyzed by ion chromatography for quantitative
assessment of bromine and chlorine content. Samples weighing between 400 and 800 mg were
tested by Galbraith Laboratories45 following procedure ME-4A (Determination of Anions by
Suppressed Ion Chromatography). Measurement accuracy for the ME-4A quantitative method
was ±10 %.
Foam and fire barrier materials exhibiting chlorine concentrations exceeding than the 2 % upper
concentration limit of the ME-4A quantitative assessment of bromine and chlorine content
method were also titrated by Galbraith Laboratories46 using procedure E17-1 (Determination of
Total Halogens or Total Halides by Potentiometric Titration) to assess halogen content. To
determine the total halogen content, 20 to 70 mg samples were converted to halides by
(Schoniger) oxygen flask combustion (G-54 or ASTM E-442) absorbed in a 2% hydrazine
sulfate solution (liquid samples were weighed into gelatin capsules prior to combustion).
Chloride, bromide, and iodide were automatically titrated with dilute AgNO3 potentiometrically
to calculate the resulting Total Halogens as Chlorine. Measurement accuracy for the E17-1
quantitative method was ±0.71 %.
Pyrolysis-GC/MS (Py-GC/MS)
Volatile, semi-volatile and non-volatile components present in the fabric, foam, and barrier
materials were analyzed with a Frontier Laboratories PY-2020iD Py-GC/MS. Approximately 0.1
mg solid samples were placed in the Auto-Shot Sampler for introduction into the pyrolyzer
furnace. Released compounds were trapped and focused in a Micro-Jet Cryo Trap before being
introduced into the gas chromatography column. The carrier gas was 99.995% pure helium and
the separation column was a stainless-steel capillary coated with 5% diphenyldimethyl
polysiloxane (Ultra ALLOY-5: 30 m length, 0.25 mm inner diameter with 0.25 μm of the film
thickness, Frontier Laboratories). Compounds were eluted at different retention times to a mass
spectrometer downstream. The mass spectrometer broke each molecule into ionized fragments
and detected the fragments by their mass to charge ratio.
The pyrolyzer furnace was operated in three analysis modes:
1. Evolved Gas Analysis (EGA) for the polymer identification: The sample was introduced into
the 50 °C furnace, held for 1 minute to equilibrate, and then heated to 700 °C at a rate of 20
°C/min. The polymeric material was identified by comparison of the EGA data to an EGA
library.
2. Thermal Desorption (TD): The sample was injected at 50 °C, held for 1 minute to equilibrate,
and then heated to 350 °C at a rate of 20 °C/min. As the temperature increased, individual
compounds desorbed from the sample and were carried to the splitter and ultimately to the
MS detector. The elute compounds were identified by comparison to either NIST or F-Search
Additive libraries.
45
46
P. 20
3. Pyrolysis: The sample was introduced into the 550 °C furnace where it was pyrolyzed into
characteristic fragments. Polymer species were identified through collection of the pyrolyzed
fragments and comparison to an F-Search Polymer/Pyrolyzate library.
Testing was conducted in triplicate.
Thermal Degradation (TGA)
Thermal degradation behavior of the fabric, foam, and barrier materials was characterized using
a TA Instruments model Q500 TGA with an evolved gas analysis (EGA) furnace. Samples
weighing between 10 to 50 milligrams were heated from 40 to 850 °C at 20 °C/min under a 90
mL/min dry air flow rate.
SEM-EDS
Fabric, foam, and barrier materials were analyzed using a Jeol JSM-6701F scanning electron
microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) to determine the inorganic
content of the fabric, foam, and barrier materials. Samples were coated with a thin layer of gold
for electric conductivity. Analysis was performed under high vacuum conditions utilizing a 20kV
accelerating voltage and a working distance of approximately 15 mm. The electron beam current
was 10 A and the measuring time was 60 s.
Potential Heat
Potential heat of the materials was measured in accordance with NFPA 259 Standard Test
Method for Potential Heat of Building Materials 47 using a Parr oxygen isoperibol bomb
calorimeter under a high-pressure oxygen environment. The bomb calorimeter is calibrated by
one-gram benzoic acid pellets with a known heat of combustion of 26.43 kJ/g (11,373 BTU/lb).
A gross calorific value is defined as the amount of heat liberated per unit mass of a sample when
burned in oxygen at a constant volume vessel.
Combustibility
The combustibility behavior of the untreated and flame retardant treated foams was characterized
under flaming conditions using a cone calorimeter in accordance with test method ASTM E 1354
Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products
Using an Oxygen Consumption Calorimeter 48.
Foam test specimen measuring 100  100 mm square by 51 mm thick were cut and tested in a
horizontal orientation using an edge frame sample holder with a restraining grid (HEG) such that
the intended outer surface of the material was exposed to the applied radiant heat flux, Figure 15.
47
NFPA 259 Standard test Method for Potential Heat of Building Materials, National Fire Protection
Association, United States (20130.
48
ASTM E 1354 Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products
Using an Oxygen Consumption Calorimeter, ASTM International, United States (2013).
P. 21
Figure 15: ASTM E1354 Cone calorimeter sample holder
Tests were performed, in triplicate, at 30 kW/m2 radiant heat flux setting on the conical heater
and using an electric spark igniter to ignite the thermal decomposition gases. Data was collected
until flaming or other signs of combustion ceased. Samples were exposed until flaming
combustion ceased for more than 2 minutes or for a maximum of 60 minutes (as specified in
ASTM E 1354) in order to collect sufficient data for this investigation. Observations regarding
ignition time and physical changes to the sample (e.g. melting, swelling, or cracking) were also
noted.
Heat release rates and effective heats of combustion were calculated using the procedures
described in ASTM E 1354 and are summarized in the following equations.
HRR =
Measured heat
[=] kW/m2
Sample area
completion
Total Heat =
ignition
HRR  dt
1000 MJ / kJ
Effective Heat of Combustion =
[=] MJ/m2
Total Heat  Sample area
[=] kJ/g
Total weight loss  1000 kJ/MJ
Eq. 1
Eq. 2
Eq. 3
RESULTS
Density
The PU foam volume density (and SD) was measured to be 29.6 ±0.6 kg/m3; the frPU foam was
measured to be 27.6 ±0.6 kg/m3.
Area densities measured for the fabric and barriers are listed in Table 7.
P. 22
Table 7: Area density of fabric and barrier materials (expressed as mean ±SD).
Material ID
C
D
W
FB1
FB2
FB3
FB4
FB5
FB6
FB7
FB8
FB9
FB10
FB11
2
Area Density (g/m )
717.9 ±6.3
1036.1 ±15.4
1443.9 ±83.7
295.8 ±21.3
268.7 ±12.6
463.6 ±5.1
869.6 ±27.5
1177.6 ±32.0
684.6 ±4.7
1325.6 ±143.9
1095.7 ±93.3
1434.3 ±54.7
1060.4 ±123.5
1548.2 ±127.2
Thickness
Measured flat barrier and uncompressed high-loft barrier thickness are listed in Table 8.
Table 8: Barrier material thickness (expressed as mean ±SD).
Material ID
FB1
FB2
FB3
FB4
FB5
FB6
FB7
FB8
FB9
FB10
FB11
Thickness (mm)
0.3 ±0.0
0.4 ±0.0
0.1 ±0.0
0.6 ±0.0
0.8 ±0.0
0.3 ±0.0
7.3 ±0.6
8.0 ±0.7
8.3 ±0.4
10.1 ±0.8
7.2 ±0.7
Chemistry (FTIR)
Measured FTIR spectra for the materials are shown in Figure 16 through Figure 25. Analysis of
the spectra indicated both the face and back-side of cover fabric C were polyester and were
consistent with the polyester wrap W (Figure 16). Foam spectra for the foams (Figure 17)
indicated that the foams were a polypropylene oxide polyol, polyether based polyurethane.
Results for the two para-aramid flat sheet barriers FB1 and FB2 confirmed the para-aramid base
material and revealed the incorporation of polyester and rayon in FB1 (Figure 18). The FR
coated glass-fiber sheet FB3 appears to be either a melamine derivative or a styrene/acrylic
derivative (Figure 19). Elastic knit flat barriers FB4 and FB5 were based on a PAN-PVC
copolymer and chemically the same (Figure 20); elastic knit flat barrier FB6 appeared to be
based on PAN-PVC but also incorporated cotton (Figure 20). High-loft barrier FB7 was
determined to be predominantly cotton whereas high-loft barrier FB9 was predominantly rayon,
and both exhibited evidence of PET (Figure 21). Multilayer high-loft barriers FB8 and FB10 had
P. 23
sides that were predominantly cotton or rayon, and both exhibited evidence of PET (Figure 22
and Figure 23 respectively). High-loft barrier FB11 was found to be a mixture of cotton, rayon
and PET (Figure 24). Decking D was determined to be cotton (Figure 25).
Figure 16: FTIR spectra for cover fabric C and polyester wrap W.
P. 24
Figure 17: FTIR spectra for PU and frPU foams.
Figure 18: FTIR spectra for para-aramid flat fire barriers FB1 and FB2.
P. 25
Figure 19: FTIR spectra for flat fire barrier FB3.
Figure 20: FTIR spectra for elastic knit flat fire barriers FB4, FB5, and FB6.
P. 26
Figure 21: FTIR spectra for cotton high-loft fire barrier FB7 and rayon high-loft fire barrier FB9.
Figure 22: FTIR spectra for two-layer (cotton/rayon) high-loft fire barrier FB8.
P. 27
Figure 23: FTIR spectra for three-layer (cotton/rayon/rayon) high-loft fire barrier FB10.
Figure 24: FTIR spectra for high-loft fire barrier FB11.
P. 28
Figure 25: FTIR spectra for decking D.
Elemental Analysis (ICP-MS)
The foams, fabric and barriers were analyzed for inorganic element content. Of the 65
investigated elements, 52 elements were detected at trace concentrations or not detected. These
elements were (listed in order of elemental mass): Lithium, Beryllium, Scandium, Vanadium,
Chromium, Manganese, Cobalt, Nickel, Copper, Gallium, Germanium, Arsenic, Selenium,
Rubidium, Yttrium, Zirconium, Niobium, Molybdenum, Ruthenium, Rhodium, Palladium,
Cadmium, Indium, Tellurium, Cesium, Barium, Lanthanum, Cerium, Praseodymium,
Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium,
Thulium, Ytterbium, Lutetium, Hafnium, Tantalum, Tungsten, Rhenium, Iridium, Platinum,
Gold, Thallium, Lead, Bismuth, Thorium, and Uranium.
Measured concentrations of the remaining 13 elements (Boron, Sodium, Magnesium, Aluminum,
Phosphorus, Potassium, Calcium, Titanium, Iron, Zinc, Strontium, Tin, and Antimony) are listed
in Table 9.
P. 29
Table 9: Semi-quantitative elemental analysis by ICP-MS.
Calcium
Titanium
Iron
Zinc
Strontium
Tin
Antimony
C
2
55
39
45
25
D
10
341
515
25
162
PU
2
78
26
56
65
frPU
5
81
43
89
5063
W
<2
21
5
7
49
FB1
7
1314
99
71
86
FB2
<3
4828
79
23
74
FB3
3968
1934
1881
Major
73
FB4
3104
1915
1018
Major
65
FB5
2373
1681
813
Major
44
FB6
3097
1852
1202
19344
186
FB7
4960
92
549
46
332
FB8 - top
2913
253
485
31
257
FB8 - below
2298
932
133
51
74
FB9
228
1523
34
40
23
FB10 - top
3161
949
259
46
112
FB10 - below
2945
956
135
44
70
FB11
11
129
68
24
<20
[1]
Notes:
NA = measurement not reliable for reporting purposes
[2]
Major = measurement exceeded upper limit
[1] [2]
Potassium
Phosphorus
Aluminum
Magnesium
Sodium
Material ID
Boron
Element Concentration (ppm)
40
236
109
97
51
166
165
449
433
399
NA
NA
NA
NA
NA
NA
NA
NA
256
193
68
132
14
238
503
Major
Major
Major
NA
NA
NA
NA
NA
NA
NA
NA
539
3
3
10
194
30
<3
379
252
151
228
32
22
24
75
18
23
42
152
66
79
165
19
77
141
642
505
231
420
33
23
<20
<2
<20
<20
<20
12
10
16
27
4
18
10
12
7
5
9
10
34
140
200
71
107
12
<2
2
<2
<2
<2
5
8
613
434
322
436
7
5
<2
<2
<2
<2
<2
3
<2
228
477
<2
<2
5
<2
<2
<2
<2
<2
<2
<2
<2
<2
<2
<2
126
<2
<2
3
290
37
<3
252
8468
2237
3215
58
48
27
23
43
41
8
P. 30
Quantitative Elemental Analysis (Boron, Bromine and Chlorine)
Quantitative elemental analysis of the foams, fabric and barriers for boron, bromine and chlorine
is listed in Table 10. These three elements are characteristic of flame retardants known to be used
in textile products. Boric acid is a flame retardant regularly used to treat cellulosic materials such
as cotton. Cotton-based high-loft fire barriers FB7, FB8 and FB10 exhibited elevated boron
levels suggesting the likely use of boric acid or a borate whereas the rayon-based high-loft fire
barrier FB9 and the cotton-rayon-polyester blend high-loft fire barrier FB11 did not. Bromine
and chlorine are the active elements in halogenated flame retardants. High concentrations of
chlorine observed for fire barriers FB4, FB5, and FB6 (in excess of 6 %) are consistent with the
PAN-PVC copolymer base observed by FTIR. Elevated concentrations of chlorine in the flame
retardant treated foam frPU, and fire barriers FB3 and FB10 (top) suggest the presence of
chlorinated chemical moiety such as a flame retardant or chlorinated paraffin.
Table 10: Quantitative elemental analysis results for flame retardant characteristic elements.
[1]
Note:
Material ID
Boron
Bromine
Chlorine
PU
-153 ppm
490 ppm
frPU
-45 ppm
1.880 %
FB1
-37 ppm
224 ppm
FB2
-<27 ppm
117 ppm
FB3
-51 ppm
0.793 %
FB4
-<20 ppm
16.80 %
FB5
-< 13 ppm
16.98 %
FB6
-< 24 ppm
6.37 %
FB7
0.489 %
< 29 ppm
528 ppm
FB8 - top
0.366 %
< 34 ppm
230 ppm
FB8 - below
0.667 %
<32 ppm
90 ppm
FB9
314 ppm
< 39 ppm
160 ppm
FB10 - top
0.265 %
<31 ppm
0.145 %
FB10 - below
0.330 %
<31 ppm
149 ppm
FB11
5 ppm
<29 ppm
186 ppm
[1]
Reported chlorine concentrations less than 2 % measured by ME-71 method;
concentrations greater than 2 % measured by E17-1 method.
Pyrolysis-GC/MS (Py-GC/MS)
The foams, fabric and barriers were analyzed by pyrolysis-GC/MS for presence of flame
retardants and other additives.
Analysis of the PU and frPU foam indicated the foams to be based on 2,4-toluene diisocyanate
(TDI) and propylene glycol. Additives detected in the foams included a Ciba-Geigy antioxidant
and an alkylated diphenylamine costabilizer. Three flame retardant chemicals were found in the
frPU: tris(1,3-dichloroisopropyl)phosphate (TDCPP), triphenyl phosphate (TPP), and tris(4-tertbutylphenyl) phenyl phosphate (TBPP). The concentration of flame retardants was found to be
approximately 3 %, which is consistent with concentrations reported by Stapleton et al49.
49
Stapleton, H.M., Klosterhaus, S., Eagle, S., Fuh, J., Meeker, J.D., Blum, A. and Webster, T.F. Organophosphate
Flame Retardants in Furniture Foam and US House Dust. Environ. Sci. Technol., 2009, 43 (19), pp 7490–7495.
P. 31
Analysis of the cover fabric C indicated a 1 % concentration of polyurethane, most likely used as
a binder, and the decking D had a polydimethylsiloxane (PDMS) treatment.
Analysis of the barriers indicated flame retardants in flat barriers FB3-6. FB3 contained four
flame retardant chemicals: triphenyl phosphate (TPP), tris(4-tert-butylphenyl) phenyl phosphate
(TBPP), and a chlorinated paraffin. The concentration of flame retardants was found to be
approximately 3 %. Antimony chloride (SbCl3) was also detected suggesting presence of
antimony trioxide (Sb2O3), a flame retardant synergist to the halogenated flame retardants. Knit
flat barriers FB4- 6 also exhibited antimony chloride suggesting antimony trioxide which would
have a synergistic flame retardant effect with the PAN-PVC base material. No halogenated flame
retardant chemistries were found for any of the other barriers.
The antimony trioxide results are consistent with the semi-quantitative antimony elemental
analysis results (FB3-6) and the detection of chlorinated additives is consistent with the
quantitative chlorine elemental analysis results (frPU and FB3). These results also confirm that
the chlorine detected in the quantitative elemental analysis for FB4-6 is from the PAN-PVC
copolymer base and not from flame retardant additives.
Thermal Degradation (TGA)
Measured FTIR spectra for the materials are shown in Figure 26 through Figure 43. Analysis of
the results for the polyester microsuede cover fabric C (Figure 26) and the polyester wrap W
(Figure 29) indicated the same thermal degradation behavior as characterized by the two-stage
degradation behavior, onset temperature, peak degradation rate temperature, and degradation
residue content. Thermal degradation behavior of the flame retardant treated foam frPU (Figure
28) versus the polyurethane foam PU (Figure 27) is consistent with behavior observed for other
halogenated flame retardant materials, namely a lower degradation onset temperature (143 vs.
154 °C) and increased degradation rate at lower temperatures. Degradation residue content was
greater for the frPU than the PU foam (2.5 vs. 1.5 %) most likely due to the inorganic phosphate
component of the halogenated flame retardants.
Analysis of the para-aramid flat sheet fire barrier FB1 results (Figure 30) indicates the barrier is
approximately 22 % rayon, 26 % polyester, 40 % para-aramid, and 12 % inorganic material. In
contrast to FB1, para-aramid flat sheet fire barrier FB2 (Figure 31) appears to be entirely paraaramid.
The FR coated glass-fiber sheet FB3 appears to be approximately 92 % inorganic material
(Figure 32). Elastic knit flat barriers FB4 and FB5 exhibit similar multi-stage degradation
consistent with the PAN-PVC copolymer identified by FTIR and inorganic material with slight
differences in composition (Figure 33 and Figure 34 respectively). Degradation behavior of
elastic knit flat barrier FB6 appeared to be similar to FB4 and FB5 but also exhibited a
degradation stage consistent with cotton (Figure 35). Degradation residue content of the three
knit barriers was 41 %, 45 % and 42 % respectively.
High-loft barriers FB7 through FB10 exhibited similar degradation behaviors consistent with
cotton and rayon and inorganic residue contents ranging from 6 to 23 % (Figure 36 through
Figure 41). Degradation of high-loft barrier FB11 was found to be consistent with a mixture of
P. 32
cotton, rayon and PET and had a 22 % inorganic residue content (Figure 42). Decking D had
approximately 2 % residual inorganic content (Figure 43).
Figure 26: TGA results for cover fabric C.
P. 33
Figure 27: TGA results for polyurethane foam PU.
Figure 28: TGA results for flame retardant treated polyurethane foam frPU.
P. 34
Figure 29: TGA results for polyester wrap W.
Figure 30: TGA results for para-aramid flat fire barrier FB1.
P. 35
Figure 31: TGA results for para-aramid flat fire barrier FB2.
Figure 32: TGA results for flat fire barrier FB3.
P. 36
Figure 33: TGA results for elastic knit flat fire barrier FB4.
P. 37
Figure 36: TGA results for cotton high-loft fire barrier FB7.
P. 38
Figure 37: TGA results for rayon layer of two-layer high-loft fire barrier FB8.
Figure 38: TGA results for cotton layer of two-layer high-loft fire barrier FB8.
P. 39
Figure 39: TGA results for rayon high-loft fire barrier FB9.
Figure 40: TGA results for rayon layer of three-layer high-loft fire barrier FB10.
P. 40
Figure 41: TGA results for cotton layer of three-layer high-loft fire barrier FB10.
Figure 42: TGA results for high-loft fire barrier FB11.
P. 41
Figure 43: TGA results for decking D.
SEM-EDS
Fabric, foam, and barrier materials were analyzed by SEM-EDS to determine elemental
composition. Weight and atomic fraction results are summarized in Table 11 and Table 12.
Chlorine and phosphate levels observed in the frPU foam were consistent with the presence of
chlorinated organophosphate flame retardants and chlorinated paraffins found by Py-GC/MS.
The higher chlorine levels found in fire barriers FB3-6 were consistent with the chlorinated
flame retardants detected in FB3 by Py-GC/MS and the PAN-PVC copolymer detected in FB4-6
by FTIR. Concentration trends in the observed chlorine levels corroborated results from the wet
chemistry techniques used for quantitative elemental analysis.
Fire barriers FB3-6 results indicated calcium and aluminum silicates. The high-loft barriers with
rayon (FB8 – top, FB9, FB10 – top, FB11) appeared to have silica. Because silicates and silica
are inorganic, they would remain in TGA testing residue.
P. 42
Table 11: SEM-EDS quantified elemental composition (weight fraction) of fabric, foam and barrier materials.
Material ID
C
O
N
Ti
Si
C
60.95 38.82
-0.23
-D
49.04 50.53
--0.25
PU
66.58 33.25
---frPU
63.57 35.64
---W
59.94 39.96
--0.10
FB1
52.55 41.44
--4.31
FB2
76.10 18.91
---FB3
36.48 39.60
--8.86
FB4
47.81 7.98 16.82
-0.54
FB5
49.88 8.57 17.23
-0.46
FB6
56.33 35.90
---FB7
48.30 50.99
---FB8 – top
34.65 55.51
--9.17
FB8 – bottom
49.93 46.40
--1.15
FB9
46.13 47.84
--5.35
FB10 - top
44.07 50.65
--4.92
FB10 - bottom 52.34 47.24
--0.26
FB11
36.44 53.72
--8.83
[1]
Note:
Sum may not add to 100.00 due to rounding.
P
---0.21
---------------
Weight Fraction (%)
Cl
Al
Na
---0.18
--0.16
--0.58
-------0.52
2.39
3.75
-21.90 0.17
-19.20 0.19
-6.37
------------------------
S
-----0.23
1.31
--0.14
---------
Ca
-------7.07
0.59
0.46
---------
Sb
-------1.85
4.22
3.90
1.17
--------
K
----------0.24
0.70
-0.95
--0.16
--
Zn
-----0.72
1.31
------------
Cu
-----0.74
1.86
-----0.66
1.58
0.68
0.36
-1.00
SUM
[1]
100.00
100.00
99.99
100.00
100.00
99.99
100.01
100.00
100.00
100.01
100.01
99.99
99.99
100.01
100.00
100.00
100.00
99.99
P. 43
Table 12: SEM-EDS quantified elemental composition (atomic fraction) of fabric, foam and barrier materials.
Material ID
C
D
PU
frPU
W
FB1
FB2
FB3
FB4
FB5
FB6
FB7
FB8 – top
FB8 – bottom
FB9
FB10 - top
FB10 - bottom
FB11
C
67.61
56.28
72.69
70.16
66.61
61.20
83.03
48.78
62.47
63.59
65.78
55.65
43.11
58.16
54.62
52.30
59.50
45.14
O
32.33
43.53
27.25
29.53
33.34
36.23
15.49
39.76
7.83
8.20
31.47
44.10
51.85
40.58
42.52
45.12
40.32
49.95
N
--------18.85
18.84
---------
Ti
0.06
------------------
Si
-0.12
--0.05
2.15
-5.07
0.30
0.25
--4.88
0.57
2.71
2.50
0.13
4.68
P
---0.09
---------------
Atomic Fraction (%)
Cl
Al
Na
---0.07
--0.06
--0.22
----------0.30
1.08
2.23
-9.68
0.10
-8.28
0.11
-2.52
------------------------
S
-----0.10
0.54
--0.07
---------
Ca
-------2.83
0.23
0.18
---------
Sb
-------0.24
0.54
0.49
0.13
--------
K
----------0.09
0.25
-0.34
--0.06
--
Zn
-----0.15
0.26
------------
Cu
-----0.16
0.38
-----0.16
0.35
0.15
0.08
-0.23
SUM
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
P. 44
Potential Heat
Potential heat measured for the foams, fabric and barriers are listed in Table 13.
Table 13: Potential heat of foams, fabric and barrier materials (expressed as mean ±SD).
Material ID
C
D
PU
frPU
W
FB1
FB2
FB3
FB4
FB5
FB6
FB7
FB8
FB9
FB10
FB11
Potential Heat (kJ/kg)
21689 ±2
17238 ±28
28167 ±602
26899 ±374
22510 ±178
18989 ±293
25793 ±361
1827 ±59
12039 ±170
11630 ±341
10402 ±33
16875 ±82
15805 ±167
13360 ±167
14437 ±112
13291 ±117
Combustibility
The cone calorimeter combustibility results from the tests included ignition time, sample weight,
heat release rate, effective heat of combustion, and specific extinction area. Average and
standard deviation combustibility data for the two foam types are summarized in Table 14; heat
release rates for the two foams are plotted in Figure 44 and Figure 45 respectively. The effective
heat of combustion, average heat release rate, and total heat were statistically significantly
different at a 0.05 level.
Table 14: Combustibility characteristics of foam materials (expressed as mean ±SD).
Foam
Material
Initial
Weight (g)
PU
frPU
15.43 ±0.27
14.41 ±0.83
Weight
Loss
(%)
100.00
100.00
Ignition Eff. Heat of Avr. HRR. at
Peak HRR
Time
Combustion
180 s
(kW/m²)
(s)
(kJ/g)
(kW/m²)
3 ±1
25.4 ±0.1
212 ±11
284 ±27
8 ±6
22.8 ±0.2
191 ±15
303 ±26
Total Heat
(MJ/m²)
44.6 ±0.9
37.4 ±2.4
P. 45
Figure 44: Cone calorimeter measured heat release rate profiles for polyurethane (PU) foam.
Figure 45: Cone calorimeter measured heat release rate profiles for flame retardant treated polyurethane
(frPU) foam.
P. 46
SUMMARY
Material characteristics for the cover fabric and the decking are summarized in Table 15,
untreated and treated polyurethane foams in Table 16, flat fire barriers in Table 17, and high-loft
fire barriers in Table 18.
Table 15: Material characteristics of cover fabric and decking.
Characteristic
Color
Bulk Material
Inorganic Residue (%)
2
Area Density (g/m )
Notes
Cover Fabric C
Beige
Polyester
1.4
717.9 ±6.3
21689 ±2
Polyurethane binder
Decking D
Beige
Cotton
2.1
1036.1 ±15.4
17238 ±28
Polydimethylsiloxane treatment
Table 16: Material characteristics of untreated and treated polyurethane foams (expressed as mean ±SD).
Characteristic
Color
Bulk Material
Antioxidant
Costabilizer
Flame Retardant Chemicals
3
Density (g/m )
Eff. Heat of Combustion (kJ/g)
Peak HRR (kW/m²)
Untreated Foam PU
White
80:20 TDI/polypropylene oxide
polyol, polyether based
polyurethane
Ciba-Geigy
Alkylated diphenylamine
-1.5
29.6 ±0.6
28167 ±602
25.4 ±0.1
284 ±27
Treated Foam frPU
White
80:20 TDI/polypropylene oxide
polyol, polyether based
polyurethane
Ciba-Geigy
Alkylated diphenylamine
TDCPP, TPP, TBPP
2.5
27.6 ±0.6
26899 ±374
22.8 ±0.2
303 ±26
P. 47
Table 17: Material characteristics of flat fire barriers (expressed as mean ±SD).
Characteristic
Color
Bulk Material
FB1
Yellow
FB2
Yellow
Para-aramid/
polyester/rayon
blend
Para-aramid
Flame Retardant
Chemicals
12
< 0.1
295.8 ±21.3
0.3 ±0.0
18989 ±293
268.7 ±12.6
0.4 ±0.0
25793 ±361
Inorganic Additives
2
Area Density (g/m )
Thickness (mm)
FB3
White
melamine or
styrene/acrylic
derivative coated
glass fiber
TPP, TBPP,
Chlorinated
paraffin,
Antimony trioxide
92
calcium and
aluminum
silicates
463.6 ±5.1
0.1 ±0.0
1827 ±59
FB4
Off-white
FB5
Off-white
FB6
Off-white
PAN-PVC
copolymer
PAN-PVC
copolymer
PAN-PVC
copolymer and
cotton
Antimony trioxide
Antimony trioxide
Antimony trioxide
41
calcium and
aluminum
silicates
869.6 ±27.5
0.6 ±0.0
12039 ±170
45
calcium and
aluminum
silicates
1177.6 ±32.0
0.8 ±0.0
11630 ±341
42
calcium and
aluminum
silicates
684.6 ±4.7
0.3 ±0.0
10402 ±33
Table 18: Material characteristics of high-loft fire barriers and polyester wrap (expressed as mean ±SD).
Characteristic
Color
Bulk Material
FB7
Off-white
Cotton
FB8
Off-white
Cotton-Rayon
bilayer
Flame Retardant
Boric acid
Boric acid
Chemicals
[1]
7
Inorganic Additives
silica
2
Area Density (g/m )
1325.6 ±143.9
1095.7 ±93.3
Thickness (mm)
7.3 ±0.6
8.0 ±0.7
16875 ±82
15805 ±167
[1]
Note:
Individual layers measured but not composite structure.
FB9
Off-white
Rayon
FB10
Off-white
Cotton-RayonRayon trilayer
FB11
Off-white
Cotton/polyester/
rayon blend
Poly Wrap W
White
22
silica
1548.2 ±127.2
7.2 ±0.7
13291 ±117
1
Polyester
Boric acid
22
silica
1434.3 ±54.7
8.3 ±0.4
13360 ±167
[1]
silica
1060.4 ±123.5
10.1 ±0.8
14437 ±112
1443.9 ±83.7
22510 ±178
P. 48
TASK 3 – MATERIAL COMBINATION COMBUSTIBILITY
EXPERIMENTS
Combustibility of various combinations of foam, polyester wrap, barrier material and cover
fabric as would be used in upholstered furniture construction practice was characterized under
flaming conditions by oxygen consumption calorimetry (cone calorimeter) to assess materiallevel performance differences. The ASTM E 1354 cone calorimeter was selected for this task
because it can simulate well-ventilated, early stage fires and allows control of the heating
conditions leading to thermal decomposition and ignition of the sample. Component
combinations exhibiting longer times to ignition, lower heat release rates, and/or shorter flaming
durations would be expected to perform better to open flame exposure.
SAMPLES
Component combustibility specimens were based on 100  100 mm (4  4 in.) square foam
blocks layered with the components of interest and wrapped in cover fabric. Fire resistant barrier,
when used, was positioned immediately adjacent to the cover fabric. Flat fire resistant barriers
were evaluated with polyester wrap between the barrier and the foam; polyester wrap was not
used in the high-loft barrier samples. The foam/wrap/barrier sample assembly was wrapped in a
single piece of cover fabric, cut pattern depicted in Figure 46. The cover fabric piece center was
draped over the top of the sample assembly and the extensions were wrapped around the sides
and overlapped the bottom. Samples fell into one of the following categories (cross-section with
description extending from the center upward):
Foam, cover fabric
Foam, polyester wrap, cover fabric
POLYESTER WRAP
FOAM
Foam, polyester wrap, flat barrier, cover fabric
FOAM
Foam, high-loft barrier, cover fabric
FLAT BARRIER
POLYESTER WRAP
HIGH-LOFT BARRIER
FOAM
FOAM
Experiment samples are summarized in Table 19.
P. 49
Table 19: Component experiment samples for cone calorimeter combustibility measurement.
Foam
Foam Thickness
Type
(mm)
PU25-C
PU
25
PU25-W-C
PU
25
PU25-FB7-C
PU
25
PU25-FB8-C
PU
25
PU25-FB9-C
PU
25
PU25-FB10-C
PU
25
PU25-FB11-C
PU
25
PU51-C
PU
51
PU51-W-C
PU
51
PU51-W-FB1-C
PU
51
PU51-W-FB2-C
PU
51
PU51-W-FB3-C
PU
51
PU51-W-FB4-C
PU
51
PU51-W-FB5-C
PU
51
PU51-W-FB6-C
PU
51
frPU51-C
frPU
51
frPU51-W-C
frPU
51
[1]
Note:
Expressed as mean ±SD
Sample ID
Polyester
Wrap
-X
------X
X
X
X
X
X
X
-X
Barrier
--FB7
FB8
FB9
FB10
FB11
--FB1
FB2
FB3
FB4
FB5
FB6
---
Initial Weight
[1]
(g)
22.95 ±0.36
25.63 ±0.18
24.50 ±0.29
24.20 ±0.03
24.62 ±0.44
23.66 ±0.40
24.35 ±0.47
30.88 ±0.27
33.61 ±0.75
42.69 ±0.57
40.12 ±0.32
40.50 ±0.69
43.20 ±2.00
51.38 ±0.50
45.68 ±2.33
29.66 ±0.40
33.15 ±0.74
P. 50
Bottom
Bottom
Top
Bottom
Top
Bottom
Figure 46: Cone calorimeter cover fabric cut layout (left) and sample (right). Dashed lines are fold lines;
cross-hatched regions are overlapping portions on the sample bottom.
EXPERIMENTAL
The combustibility behavior of the samples under flaming conditions was evaluated using a cone
calorimeter in accordance with test method ASTM E 1354 Standard Test Method for Heat and
Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption
Calorimeter 50 as described in Task 2 – Characterization of Sample Materials. Experiments were
performed, in triplicate, at 30 kW/m2 radiant heat flux setting on the conical heater and using an
electric spark igniter to ignite the thermal decomposition gases. Data was collected until flaming
or other signs of combustion ceased. Samples were exposed until flaming combustion ceased for
more than 2 minutes or for a maximum of 60 minutes (as specified in ASTM E 1354) in order to
collect sufficient data for this investigation. Observations regarding ignition time and physical
changes to the sample (e.g. melting, swelling, or cracking) were also noted.
50
ASTM E 1354 Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using
an Oxygen Consumption Calorimeter, ASTM International, United States (2013).
P. 51
Samples were conditioned at a temperature of 23 ±3 °C (77 ±5 °F) and a relative humidity of 50
±5 % for a minimum of 168 hours prior to testing. Note that these temperature and humidity
conditions are consistent with ASTM E 1354.
RESULTS
The cone calorimeter ignition behavior from the experiments included observation of flashing
both prior to ignition as well as after ignition, ignition time, and where applicable, reignition
time. Results are summarized in Table 20 and time to ignition and burn duration are plotted in
Figure 47. Sample weight loss, peak and average heat release rates, effective heat of combustion,
and total generated heat for the experiments are summarized in Table 21; heat release rates and
the effective heats of combustion are plotted in Figure 48 and Figure 49 respectively.
Pre-ignition flashing (flames lasting less than 4 seconds) was only observed for four flat barrier
combinations (FB2 and FB4-6). Three of these barrier combinations (FB 4-6), as well as one of
the high-loft barrier combinations (FB9), exhibited post-burn flashing. The two barrier
combinations that exhibited post-burn flashing, the high-loft and one flat barrier (FB4), reignited
and burned for 147 and 202 s respectively.
Table 20: Ignition behavior of cone calorimeter component arrangements.
Pre-Ignition
Flashing
(No.)
PU25-C
None
PU25-W-C
None
PU25-FB7-C
None
PU25-FB8-C
None
PU25-FB9-C
None
PU25-FB10-C
None
PU25-FB11-C
None
PU51-C
None
PU51-W-C
None
PU51-W-FB1-C
None
PU51-W-FB2-C
0, 1, 3
PU51-W-FB3-C
None
PU51-W-FB4-C
0, 0, 1
PU51-W-FB5-C
1, 0, 1
PU51-W-FB6-C
0, 0, 1
frPU51-C
None
frPU51-W-C
None
[1]
Note:
Expressed as mean ±SD
Sample ID
Ignition Time
[1]
(s)
Burn Duration
[1]
(s)
15 ±2
26 ±3
36 ±2
42 ±1
45 ±6
35 ±2
47 ±2
38 ±13
36 ±20
42 ±3
72 ±11
80 ±5
33 ±21
61 ±2
34 ±21
30 ±8
31 ±8
380 ±59
546 ±59
901 ±65
726 ±92
720 ±185
810 ±120
738 ±42
416 ±38
537 ±29
663 ±27
1405 ±81
122 ±6
104 ±14
116 ±10
121 ±12
467 ±16
522 ±11
Post-Burn
Flashing
(No.)
None
None
None
None
0, 3, 0
None
None
None
None
None
None
None
9, 0, 5
7, 3, 0
1, 1, 1
None
None
Reignition?
(duration, s)
No
No
No
No
Yes (147)
No
No
No
No
No
No
No
Yes (192, 212)
No
No
No
No
P. 52
Figure 47: Time to ignition (blue) and flame duration (red) for cone calorimeter samples. Error bars are SD.
Table 21: Burning characteristics of cone calorimeter component arrangements (expressed as mean ±SD).
Sample
Weight Loss
(%)
Peak HRR
(kW/m²)
Avr. HRR. at
180 s (kW/m²)
Total Heat
(MJ/m²)
PU25-C
PU25-W-C
PU25-FB7-C
PU25-FB8-C
PU25-FB9-C
PU25-FB10-C
PU25-FB11-C
PU51-C
PU51-W-C
PU51-W-FB1-C
PU51-W-FB2-C
PU51-W-FB3-C
PU51-W-FB4-C
PU51-W-FB5-C
PU51-W-FB6-C
frPU51-C
frPU51-W-C
94.64 ±0.64
89.64 ±1.47
91.48 ±3.09
88.93 ±9.05
84.20 ±9.65
90.01 ±5.15
81.93 ±5.08
90.58 ±0.63
95.18 ±0.81
45.47 ±0.81
79.98 ±2.19
9.01 ±0.23
30.01 ±3.11
24.27 ±0.46
22.33 ±1.16
91.17 ±0.26
89.98 ±0.43
257 ±4
242 ±11
195 ±19
223 ±2
229 ±24
230 ±10
223 ±8
266 ±21
216 ±10
213 ±13
154 ±10
150 ±1
142 ±23
183 ±1
165 ±14
199 ±9
212 ±16
184 ±3
158 ±4
84 ±6
94 ±4
94 ±12
88 ±4
96 ±3
207 ±8
182 ±4
77 ±2
40 ±5
17 ±2
36 ±6
36 ±1
45 ±8
163 ±6
176 ±13
47.8 ±0.9
49.1 ±0.2
46.0 ±3.2
44.2 ±5.5
42.8 ±5.6
44.6 ±3.3
44.6 ±1.7
65.0 ±1.2
71.3 ±2.0
41.6 ±1.4
64.6 ±6.3
3.4 ±0.6
14.8 ±5.6
9.6 ±0.7
10.0 ±1.5
59.7 ±2.0
67.0 ±3.9
Eff. Heat of
Combustion
(kJ/g)
19.3 ±0.2
18.8 ±0.4
18.1 ±0.9
18.1 ±0.5
18.2 ±0.3
18.4 ±0.6
19.7 ±0.5
20.5 ±0.2
19.6 ±0.5
18.9 ±0.5
17.7 ±2.1
8.1 ±1.7
9.9 ±3.2
6.8 ±0.7
8.6 ±0.9
19.4 ±0.4
19.8 ±0.6
P. 53
Figure 48: Peak and 180 second average heat release rates for cone calorimeter samples. Error bars are SD.
Figure 49: Effective heat of combustion for cone calorimeter samples. Error bars are SD.
P. 54
Foam Thickness
Doubling the foam thickness from 25 to 51 mm (PU25-C vs. PU51-C), corresponding to
approximately 7.9 g of additional foam and fabric, was found to more than double the length of
time to ignition and extend the burn duration by approximately 10%. This additional foam was
found to only increase the peak heat release rate by approximately 4 % but resulted in a more
significant heat output: the 180 s average heat release rate was almost 15 % greater and the total
heat release was 36 % greater. Consequently the effective heat of combustion was approximately
5.5 % greater for the increased fuel load. Heat release rate profiles are presented in Figure 50.
Figure 50: Polyurethane foam thickness effect on cone calorimeter measured combustibility.
Polyester Wrap
The additional fuel load imparted by a nominal 2.8 g layer of polyester wrap on the foam
samples was found to increase the ignition time of the thin foam combination (PU25-C vs.
PU25-W-C) but not the thicker foam (PU51-C vs. PU51-W-C) or the flame retardant treated
foam (frPU51-C vs. frPU51-W-C) samples. Burn duration, however, was extended in all three
cases by 11 to 40+ %. Comparing the effect of including polyester wrap to doubling the foam
thickness, polyester wrap has a larger effect on burn duration.
Including polyester wrap on untreated foam resulted in lower peak and 180 s average heat
release rates, lower effective heat of combustion, longer burn duration, and consequently greater
total heat release. Polyester wrap on the flame retardant treated foam (frPU) reduced peak and
180 s average heat release rates, total heat release, and effective heat of combustion. Heat release
rate profiles are plotted in Figure 51 through Figure 53.
P. 55
Figure 51: Polyester wrap effect on combustibility of 25 mm thick foam cone calorimeter samples.
Figure 52: Polyester wrap effect on combustibility of 51 mm thick foam cone calorimeter samples.
P. 56
Figure 53: Polyester wrap effect on combustibility of 51 mm thick fire-retardant treated foam cone
calorimeter samples.
Flame retardant Treated Foam
Comparison of the untreated foam to flame retardant treated foam (PU51-C vs. frPU51-C)
reveals that the flame retardant treated foam ignited sooner and burned 12 % longer, though at a
lower intensity, as characterized by the lower peak and average heat release rates, total heat
release and effective heat of combustion, Figure 54.
Substituting flame retardant treated foam in place of the untreated foam in the polyester wrap
layered samples (PU51-W-C vs. frPU51-W-C) resulted in earlier sample ignition and a 12 %
longer burn duration, though at a slightly lower intensity, as characterized by the lower peak and
average heat release rates, total heat release and effective heat of combustion, Figure 55.
P. 57
Figure 54: Comparison of cone calorimeter measured combustibility for 51 mm thick polyurethane foam and
fire-retardant treated foam samples.
Figure 55: Comparison of cone calorimeter measured combustibility for polyester wrap covered 51 mm thick
polyurethane foam and fire-retardant treated foam samples.
P. 58
High-Loft Barriers
Substituting a high-loft fire barrier for the polyester wrap (PU25-FB#-C vs. PU25-W-C)
prolonged time to ignition by 9 to 21 s and extended the burn duration by 174 to 355 s. Peak heat
release rates were found to be modestly reduced with four of five barrier combinations exhibiting
no more than an 8 % reduction and the fifth barrier combination (FB7) exhibiting a 19 %
reduction. Average heat release rates, however, were more significantly reduced by 40 to 47 %.
Despite the significant reduction in average heat release rates, the prolonged burn durations
resulted in total heat releases only reduced by 6 to 13 %. Effective heats of combustion were not
found to be statistically different at a 0.05 level. Heat release rate measurements for the five
high-loft barrier clad foam samples are presented alongside the polyester wrap covered foam
samples in Figure 56 through Figure 60.
polyurethane foam and high-loft fire barrier 7 covered foam samples.
P. 59
P. 60
P. 61
Flat Barriers
Ignition behavior of samples with a flat fire barrier inserted between the polyester wrap and the
cover fabric trended with barrier technology. Para-aramid blend barrier samples (FB 1 and 2)
took longer to ignite than the polyester wrap layered foam samples (6 and 36 s respectively) and
burned for a longer period, 106 and 868 s respectively. The other four flat barrier samples (FC36) exhibited ignition times up to twice as long as the polyester wrap layered foam samples but
burned for a significantly shorter duration, 415 to 433 s shorter. No correlation was found
between pre-ignition flashing and ignition time.
All six of the flat sheet barrier samples exhibited some form of reduction in combustibility
compared to the polyester wrap layered foam samples, Figure 61 through Figure 66. One barrier
sample (FB1) displayed a comparable peak heat release rate while the rest were 15 to 34 % lower
for all but one barrier. Average heat release rates, however, for all six barrier samples were 58 to
91 % lower. The longer burning para-aramid blend barrier samples resulted in total heat releases
9 and 42 % lower than the polyester wrap layered foam samples but only 52 and 16 % of the
samples were consumed during testing. Thus the effective heats of combustion for the two paraaramid blend barriers were not found to be statistically different from the polyester wrap layered
foam samples at a 0.05 level. Total heat releases for the four barriers exhibiting short burn
durations was 80 to 95 % less than the polyester wrap layered foam samples and only 9 to 30 %
of the samples were consumed during testing to result in less than half of the effective heats of
combustion as the polyester wrap layered foam samples.
polyurethane foam samples with and without flat fire barrier 1.
P. 62
P. 63
Figure 64: Comparison of cone calorimeter measured combustibility for polyester wrap covered foam
samples with and without flat fire barrier 4. Note reignition of two barrier clad samples.
P. 64
ANALYSIS AND DISCUSSION
Influence of Cover Fabric
The impact of the cover fabric on combustibility can be assessed from the testing completed on
the PU and frPU foams in Task 2 and the cover fabric wrapped foam samples (PU-C and frPUC) in Task 3. Results from these experiments are summarized in Table 22 and heat release rates
for the foam based samples are plotted in Figure 67 and Figure 68 respectively.
Table 22: Combustibility characteristics of foams with and without cover fabric (expressed as mean ±SD).
Sample
Initial Weight
(g)
PU51
PU51-C
frPU51
frPU51-C
15.43 ±0.27
30.88 ±0.27
14.41 ±0.83
29.66 ±0.40
Ignition
Time
(s)
3 ±1
38 ±13
8 ±6
30 ±8
Peak HRR
(kW/m²)
Avr. HRR. at
180 s (kW/m²)
Total Heat
(MJ/m²)
284 ±27
266 ±21
303 ±26
199 ±9
212 ±11
207 ±8
191 ±15
163 ±6
44.6 ±0.9
65.0 ±1.2
37.4 ±2.4
59.7 ±2.0
Eff. Heat of
Combustion
(kJ/g)
25.4 ±0.1
20.5 ±0.2
22.8 ±0.2
19.4 ±0.4
The cover fabric was found to significantly delay sample ignition (sustained flaming) for both
foam types. This delay reflects the cover fabric’s greater critical heat flux for ignition due to
material chemistry differences (polyester versus polyurethane) and physical form differences
(open-cell foam versus ultrasuede textured microfiber fabric).
P. 65
Manifestations of the chemical differences between polyester and polyurethane were also
observed in the smaller effective heat of combustions for foams wrapped in the cover fabric than
the foam alone. Potential heat measurements of the foams and cover fabric reported in Task 2
show that the polyester cover fabric has a lower potential heat than the polyurethane foams
(Table 13).
Wrapping the foam in cover fabric was found to reduce the peak and average heat release rates,
more so for the frPU foam than the PU foam. The cover fabric restricts air flow to the
combustion region thereby diminishing combustion efficiency. This effect was more pronounced
for the frPU foam based samples because the cover fabric also retarded diffusion of released
flame retardant away from the combustion region prior to engagement. Although the cover fabric
retarded the combustion process, there was sufficient energy to consume the entire sample, and
burn duration was extended.
Figure 67: Comparison of cone calorimeter measured combustibility for PU foam samples with and without
cover fabric.
P. 66
Figure 68: Comparison of cone calorimeter measured combustibility for frPU foam samples with and without
cover fabric.
Ignitability
The same cover fabric was the initial exposed surface in all of the samples. If the cover fabric is
the sole, or dominant, source of the volatilized gases that are initially ignited, then all of the
sample combinations should have the same ignitability. Given the broad range of observed
ignition times for the various combinations of foams, barriers, and wraps, it is clear that the
internal material components were a factor in sample ignition. The internal material components
may chemically alter the combustion reaction kinetics and/or physically interfere with the
production of the combustible gases. Combustion kinetics can be interfered through the release
of chemically active species that create competing chemical reactions to the combustion reaction.
Physical interferences include limiting heat transfer to internal components thereby retarding
formation of volatilized combustible gases (i.e. a thermal barrier), a physical barrier to transport
of the volatilized combustible gases from the interior components to the combustion region, and
increased thermal mass that would take longer to heat and volatilize.
Differences in time to ignition observed for just the covered foam samples may be attributed to
different factors. Increasing the foam thickness (PU25-C vs. PU51-C) does not chemically
change the sample so the associated delay in time to ignition must be due to a physical factor.
For this study, the thicker foam samples had to be slightly compressed to fit the 51 mm deep
sample holder. As a consequence of this constraint, it is likely that the greater density of the
compressed foam simply acted as a larger thermal mass that needed to be heated. The shorter
time to ignition observed for the flame retardant treated foam (frPU51-C vs. PU51-C) is
consistent with use of flame retardants that chemically interfere with the combustion reaction
P. 67
such as the chlorinated flame retardants detected in Task 2 – Characterization of Sample
Materials.
Including additional components between the foam and the exposed cover fabric will clearly act
as a physical barrier to heat and mass transfer but may also act chemically depending upon the
chemistry of the component material. Samples containing lofty materials such as the polyester
wrap or the high-loft barriers (PU25-X-C) did indeed retard ignition as compared to samples
without them (PU25-C). The absence of a statistically significant change in ignition time (at a
95% confidence level) observed for the thicker foam sample combinations (PU51-C vs. PU51W-C, frPU51-C vs. frPU51-W-C) may be attributed to the compressed nature of the sample. The
absence of benefit observed for the wrap in the thicker samples indicates that the wrap does not
act as a chemical barrier to ignition but as a physical barrier, with thermal insulation being its
primary mode.
Like the lofty polyester wrap, the high-loft barrier materials were also expected to act as a
physical barrier retarding ignition. Ignition times for all of the high-loft barrier clad samples
(PU25-FB#-C) were greater than that of the comparable polyester wrap clad sample (PU25-WC). This may have been in part due to their thicker loft thereby providing more of a barrier.
Variation in the ignition times for the high-loft barrier samples however suggests that some of
the barrier materials may have also chemically interfered in the combustion process resulting in
even longer ignition times. Evidence for the chemical interference includes char forming cotton
found in Task 2 – Characterization of Sample Materials.
Flat fire barriers (FB1-6) were not expected to act as a thermal barrier as much as a physical
and/or chemical barrier to ignition by virtue of barrier thinness. Reduction in sample ignitability,
however, was statistically significant at the 95% confidence level for one of the flat barrier
samples (FB3) and at a 90% confidence level for two of the other flat barrier sample
combinations (FB2 and 5). Additionally four of the flat barrier sample combinations (FB2, 4-6)
exhibited pre-ignition flashing, which was not observed for any of the other sample
combinations, further corroborating evidence of those particular fire barriers interfering with the
ignition reaction. The monolithic film nature of FB3 would be expected to act as a physical
barrier to gas transport and when coupled with the chemically active organophosphate flame
retardants, chlorinated paraffin, and antimony oxide detected in Task 2 – Characterization of
Sample Materials, the significant reduction in ignitability should not be unexpected. FB4-6
incorporated PVC in their formulation so chemical interference from the chlorine is not
unexpected.
These results are not unexpected when considering placement of the flame retardant treated
component relative to the cover fabric. In the case of the flame retardant treated foam samples
(frPU-W-C), the flame retardants are initially masked by the combustible polyester wrap
whereas in the fire barrier samples (high-loft and flat barrier), the flame retardants are adjacent to
the exposed cover fabric.
Combustion Duration and Intensity
Once ignition and sustained flaming occurred, burn intensity and duration become limited by the
diffusion rate of volatilized combustible gases to the mixed air-fuel flame region. Barriers more
P. 68
effective at inhibiting the transport of volatilized gases, either by retarding the rate of
volatilization, hindering diffusion, or via chemically competitive reactions, will be more
effective at retarding combustion and therefore reducing burn intensity. Correspondingly the
burn duration will be extended provided the reduced burn intensity remains greater than the
critical flux for propagation. Should the burn intensity drop below a critical flux for propagation,
flaming combustion will cease.
Burn durations were significantly different (at 95% confidence level) when including some
component between the foam and the exposed cover fabric for every sample combination but one
(PU25-FB9-C). Typically the burn durations were longer than that of the corresponding cover
fabric covered foam sample except for four of the flat barriers which exhibited shorter burn
durations. Longer burn durations in themselves would not be surprising by virtue of the greater
combustible sample mass of the added polyester wrap and/or barrier components assuming
constant combustion rates. Considerable variation in burn durations for different component
combinations with comparable sample masses, however, indicates that the added components
also affect the combustion process. Furthermore the physical/chemical hindrance resulting from
the added component can overshadow the increased combustible mass as evidenced by the three
heaviest sample combinations exhibiting the shortest burn durations.
For materials with comparable effective heats of combustion, the law of conservation of mass
dictates that the rate of combustion must be slower in order to lengthen the burn duration for an
equivalent mass sample. And a slower rate of combustion would result in less intense burning.
All of the combinations incorporating the polyester wrap and/or barrier between the foam and the
exposed cover fabric exhibited lower burn intensities, as characterized by peak and 180 s average
heat release rates, than the corresponding cover fabric over foam samples. Reductions in the 180
s average heat release rates were significantly different (at 95% confidence level) for every
combination; reductions in the peak heat release rates were similarly significant except for
polyester wrap with the thinner foam (PU25-W-C) and high-loft barrier FB9 samples. The only
exception to this reduced burn intensity observation was the frPU foam samples in which the
peak and 180 s average heat release rates were greater when the polyester wrap was included
than without it (though not at a 95% confidence level). The impact of the inserted components on
the heat release rates confirms their role as a barrier, either physical and/or chemical in nature, to
the combustion process.
The flame retardant treatment of the foam was found to reduce the burn intensity and extend the
burn duration relative to the corresponding untreated foam samples (frPU-C vs. PU-C) similar to
what was observed in the combustibility analysis of the bare foams conducted in Task 2 –
Characterization of Sample Materials.
The results observed for the flame retardant treated foam samples and the untreated foam
samples with and without the polyester wrap (PU-C, frPU-C, PU-W-C, frPU-W-C) provides
insight on the influence of the flame retardant foam treatment relative to the polyester wrap.
Untreated foam samples with polyester wrap (PU-W-C) exhibited lower heat release rates and
longer burn durations than the corresponding samples without the polyester wrap (PU-C). This
suggests that the polyester wrap acts as a physical barrier hindering the development/transport of
P. 69
volatilized gases from the foam to the diffusion flame front thereby reducing the combustion
reaction rate (no chemical species known to chemically interfere in the combustion kinetics were
detected in the polyester wrap in the material analysis completed for Task 2 – Characterization of
Sample Materials). In contrast to this, the heat release rates were more intense and the burn
durations were longer for the flame retardant treated foam samples with polyester wrap (frPUW-C) than the corresponding samples without the polyester wrap (frPU-C). This would indicate
that the physical barrier effect of the polyester wrap hindered the liberation and/or transport
flame retardant chemicals from the foam thereby reducing the effectiveness of the competing
chemical reaction.
The flat barriers, which typically included either high-temperature polymers or chemically active
species, were more effective at reducing the burn intensity suggesting that chemical interference
is more effective than physical hindrance via loft. Samples incorporating the four flat barriers
with chemically active species (FB3-6) exhibited the lowest heat release rates and shorter burn
durations than without the barriers. It is quite likely that the combination of the physical
hindrance of the barrier in combination with the chemical interference were sufficient to reduce
the burn intensity to less than the critical flux for propagation.
Burn intensity, i.e. peak heat release rate, was found to correlate with burn duration such that
samples that burned at lower intensities tended to burn for longer durations, Figure 69. Samples
incorporating the four chemically active flat barriers (center bottom) are an exception to this
trend in that they exhibited both low peak heat release rates and short burn durations.
Figure 69: Inverse relationship between flame duration and peak heat release rate. Error bars are SD.
P. 70
The same physical/chemical interference barrier premise that explains the longer burn durations
associated with smaller heat release rates should also apply to the ease of ignition – sample
combinations that take longer to ignite should exhibit lower heat release rates. A comparison of
the time to ignition and the peak heat release rate, Figure 70, indicates an inverse trend further
substantiating this premise.
Figure 70: Inverse relationship between peak heat release rate and ignition. Error bars are SD.
Correlation between Combustibility Results
Despite the wide range of flammability results measured for the different combinations of
materials and components evaluated in this Task, a linear correlation between the effective heat
of combustion and weight loss was found as depicted in Figure 71:
Effective HOC = 0.1541 (Wt Loss %) + 5.92, R2 = 0.8329
In attempt to derive a correlation that is more physically meaningful for extrapolation of low
weight loss sample combinations, zero-intercept, second and third order relations were also
investigated. Of these only the zero-intercept, third order fit yielded adequate results with respect
to R2 values as depicted in Figure 72:
Effective HOC = 5×10-5 (Wt Loss %)3 + 0.0086 (Wt Loss %)2 + 0.6012 (Wt Loss %)
R2 = 0.8424
While the fit offered a more physically meaningful result, the slight improvement in R2 it is not
statistically significant improvement over the linear fit.
P. 71
Figure 71: First order correlation between effective heat of combustion and weight loss for cone calorimeter
samples. Error bars are SD.
Figure 72: Zero-intercept, third order correlation between effective heat of combustion and weight loss for
cone calorimeter samples. Error bars are SD.
P. 72
SUMMARY
The three investigated fire mitigation approaches (substitution of foam with flame retardant
treated foam, substitution of polyester wrap with high-loft fire barrier, and inclusion of a flat fire
barrier between the cover fabric and polyester wrap) demonstrated on a material level some
degree of reduction in ignitability and/or flammability as characterized by the time to ignition,
burn duration, peak and 180s average heat release rates, total heat release, and effective heat of
combustion:
1. Substitution of TB 117 compliant foam (frPU) for regular polyurethane foam (PU) exhibited
slightly shorter burn duration.
2. Substitution of a high-loft fire barrier (FB7 to 11) for polyester wrap (W):
 Prolonged time to ignition by 9 to 21 s; extended burn duration by 174 to 355 s
 Peak heat release rate was modestly reduced but 180 s average heat release rate was
significantly reduced
 Total heat releases were 6 to 13 % lower
3. Inclusion of a flat fire barrier (FB1 to 6) between the polyurethane foam and the cover fabric:
 Prolonged time to ignition up to twice as long
 Para-aramid blends extended burn duration by 106 and 868 s; others were 415 to 433 s
shorter
 Peak heat release rate was reduced up to 34 % and 180 s average heat release rate was
significantly reduced (58 to 91 %)
 Total heat releases for para-aramid blends was 9 and 42 % lower; others were 80 to 95 %
lower
Overall, incorporation of a barrier, whether a high-loft or a flat barrier, appeared to be more
effective at prolonging time to ignition and reducing heat release rates than substitution of the
TB 117 compliant foam in these calorimeter sized samples.
Despite differences in sample components, a reasonable correlation between weight loss and
effective heat of combustion was established for cone calorimeter samples.
P. 73
TASK 4 – MOCK-UP ASSEMBLY COMBUSTIBILITY
EXPERIMENTS
While the cone calorimeter provides important combustibility data on a material level it is
limited to 100  100 mm (4  4 in.) size samples. To overcome the sample size limitations, a
larger three sided mock-up assemblies were evaluated in this task, to determine if the material
combinations evaluated in Task 3 – Material Combination Combustibility Experiments can
retard and reduce the fire growth rate of the assemblies when exposed to an open flame ignition
source. The larger size samples in conjunction with the more complex sample geometry expand
fire growth potential by adding fuel mass, introducing multiple burning surfaces including
horizontal (bottom cushion and side cushion tops), vertical (back and side cushions), and
overhanging surfaces (crevices formed by seat cushion and the side cushions), allowing reradiation between surfaces, and permitting pool fire formation and fire spread. Ignition was also
changed from an incipient fire condition simulated in the cone calorimeter to a first item ignited
scenario using an open flame source.
SAMPLES
Mock-up assemblies were based on a three sided configuration shown in Figure 73, similar to
that used by Krasny and Babrauskas 51. The configuration was formed by a nominal 305 × 305
mm (12 × 12 in.) bottom cushion and two side cushions nominally measuring 229 × 305 mm and
229 × 229 mm (9 × 12 and 9 × 9 in.).
Figure 73: Mock-up assembly cushion arrangement example on test frame.
51
Krasny, J. and Babrauskas, V. “Burning Behavior of Upholstered Furniture Mock-Ups”, J of Fire Sci, Vol. 2, pp.
205-235 (1984).
P. 74
Cushions were based on a 76 mm (3 in.) thick foam core wrapped in the respective component
materials and inserted into a cover fabric case. Cover fabric case seams were sewn with Size 69
bonded nylon thread. The open end of the cover fabric cases were pinned closed.
The same component combinations evaluated in Task 3 – Material Combination Combustibility
Experiments were investigated in this Task. As before, high-loft barrier samples did not
incorporate the polyester wrap; while the flat sheet fire barrier samples included the polyester
wrap layered between the foam and the barrier. The fire barrier in all samples was positioned
immediately adjacent to the cover fabric. Component combinations along with sample
identification are listed in Table 23.
Table 23: Mock-up assembly experiment sample descriptions.
Sample ID
Foam Type
Polyester Wrap
Barrier
PU-C
PU-W-C
PU-FB7-C
PU-FB8-C
PU-FB9-C
PU-FB10-C
PU-FB11-C
PU-W-FB1-C
PU-W-FB2-C
PU-W-FB3-C
PU-W-FB4-C
PU-W-FB5-C
PU-W-FB6-C
frPU-C
frPU-W-C
PU
PU
PU
PU
PU
PU
PU
PU
PU
PU
PU
PU
PU
frPU
frPU
-X
-----X
X
X
X
X
X
-X
--FB7
FB8
FB9
FB10
FB11
FB1
FB2
FB3
FB4
FB5
FB6
---
Samples were conditioned in air at a temperature between 18 °C (65 °F) and 25 °C (77 °F) and a
relative humidity less than 55 % for a minimum of 168 hours prior to testing. These temperature
and humidity conditions are consistent with the Consumer Product Safety Commission’s 16 CFR
Part 1633 Standard for the Flammability (Open Flame) of Mattress Sets; Final Rule 52 and
exceed the duration requirements.
EXPERIMENTAL
Combustibility of the mock-up assemblies were evaluated on an expanded steel mesh test frame
(test frame construction details are presented in Appendix A: Mock-Up Assembly Test Frame)
placed on a load cell. The mock-up assembly was centered under a combustion products
collection hood and exhaust system equipped with an instrumentation to measure exhaust flow
and oxygen concentration. An aluminum foil lined noncombustible deck board was placed on the
52
16 CFR Part 1633 Standard for the Flammability (Open Flame) of Mattress Sets; Final Rule, US Consumer
Product Safety Commission, United States (March 2006).
P. 75
load cell below the test frame to catch materials that melted away from the mock-up assembly.
The experiment set-up is depicted in Figure 74.
Figure 74: Mock-up experiment set-up.
A match flame equivalent ignition source, BS 5852 source 1 (gas flame)53, was applied to the
interior corner of the assembly to initiate the experiments. Three sets of cushions were tested for
each component combination. The first cushion set was exposed to the ignition source for 20 s. If
the cushion set was consumed during testing, a second cushion set was to the same 20 s ignition
exposure; if the cushion set was not consumed, the second cushion set was exposed to the
ignition source for 60 s. If the second cushion set was consumed during testing, then the third
cushion set was also exposed to the ignition source for the same duration; if the second cushion
set was not consumed, then the third cushion set was exposed to the next longer exposure
duration (either 60 or 300 s). A schematic of the exposure sequence is depicted in Figure 75.
53
Specimen #1
P. 76
Specimen #2
Specimen #3
20 seconds
Consumed
20 seconds
Not
Consumed
Consumed
60 seconds
20 seconds
Not
Consumed
60 seconds
Consumed
60 seconds
Not
Consumed
300 seconds
Figure 75: Mock-up assembly experiment sample ignition exposure sequence.
Experiments were conducted in a draft free area (as defined in 16 CFR Part 1633) with
conditions maintained at 23.6 ±2.8 °C (74.5 ±5 °F) and a relative humidity of 50 ±10 %.
Mass loss and heat release rate data was collected until flaming and other signs of combustion
ceased. Experiments were recorded by video.
RESULTS
All of the mock-up assemblies ignited from the open flame exposure. Combustion behavior after
removing the ignition source flame was found to depend on the cushion components and the
duration of exposure to the ignition source such that mock-up assembly experiment results
ranged from self-extinguishing within seconds to burning for a period of time and then selfextinguishing (i.e. portions of the mock-up assembly were undamaged at experiment completion)
to consumed (i.e. no portions of the mock-up assembly were undamaged at experiment
completion). Examples of these results are shown in Figure 76.
P. 77
Figure 76: Examples of post-experiment mock-up assemblies exhibiting (L to R): rapid self-extinguishment,
delayed self-extinguishment, and consumed.
Longer durations of exposure to the ignition source flame were found to exacerbate burning for
every combination of mock-up assembly components.
The critical determinant between mock-up assemblies self-extinguishing versus being consumed
was found to be engagement of the polyurethane foam (untreated or treated) in the burning
process. None of the mock-up assemblies that self-extinguished had direct engagement of the
foam whereas every experiment in which that the foam was directly engaged resulted in the
mock-up assembly being consumed.
Experiments in which the ignition source flame exposed the foam to open flame, the fire
propagated within the cushion using the foam as the primary fuel source for further growth.
Experiments in which the foam was not exposed by the ignition source flame, fire propagation,
where it did occur, occurred along the cushion surfaces. In such cases the fire initially
propagated from the burner application point upward along the vertex formed by the two vertical
cushions and then outward from the vertical cushion vertex along the two vertical cushion faces
and the top surface of the horizontal cushion. The internal components of the mock-up assembly
cushions, i.e. fiber wrap, barrier, and foam, were found to influence the surface burning
characteristics of the cushions. Observed surface burning characteristics of the cushion ranged
from match-flame equivalent size flames fueled by the cover fabric to flame heights exceeding
380 mm fueled by volatilized gases from the barrier and foam. Examples of different observed
fire growth behaviors are shown in Figure 77 through Figure 79.
P. 78
0 seconds
10 seconds
20 seconds
60 seconds
73 seconds
100 seconds
120 seconds
300 seconds
Figure 77: Time lapse photographs of fire growth behavior in for 20 s ignition exposure of sample
combination PU-FB7-C.
P. 79
0 seconds
30 seconds
60 seconds
180 seconds
300 seconds
540 seconds
617 seconds
930 seconds
Figure 78: Time lapse photographs of fire growth behavior in for 60 s ignition exposure of sample
combination PU-FB10-C.
P. 80
0 seconds
35 seconds
60 seconds
300 seconds
551 seconds
622 seconds
754 seconds
1663 seconds
Figure 79: Time lapse photographs of fire growth behavior for 60 s ignition exposure of sample combination
PU-W-FB1-C.
In some mock-up assembly experiments where the fire propagated across cushion surface to the
far cushion end (the cushion loading end), the fire breached the “loading” seam and engaged the
foam. This behavior is depicted in Figure 80 through a series time lapse photographs. Such
P. 81
instances are indicative of further possible improvements in reducing fire growth through better
seam construction techniques.
300 seconds
420 seconds
551 seconds
622 seconds
754 seconds
1663 seconds
Figure 80: Time lapse photographs of fire propagation and seam penetration in sample combination PU-WFB1-C.
Four mock-up assembly combinations (high-loft barrier FB11, PU-W-C, frPU-C, and frPU-WC) were consumed after a 20 s ignition exposure. Six sample combinations (PU-C, flat barrier
FB1, high-loft barriers FB7, 8, 9 and 10) self-extinguished after a 20 s ignition exposure but
were consumed from a 60 s exposure. One combination (flat barrier FB2) self-extinguished after
a 60 s ignition exposure but was consumed from a 300 s exposure and four sample combinations
(flat barriers FB3, 4, 5 and 6) self-extinguished after a 300 s ignition exposure.
Total weight loss, peak heat release rate, total heat release, and heat of combustion for the
experiments are summarized in Table 24; peak heat release rate, total heat release and heat of
combustion are plotted in Figure 81 through Figure 83.
P. 82
Table 24: Mock-up assembly experiment results.
Sample
Ignition
Exposure
(s)
Weight Loss
(g)
Peak HRR
(kW)
20
2
0.2
60
685
73.3
60
552
83.2
20
650
84.5
PU-W-C
20
687
78.6
20
743
95.9
[1]
20
42.1
PU-FB7-C
20
5
1.2
60
824
41.3
20
1027
39.5
PU-FB8-C
20
3
0.6
60
909
37.7
[1]
20
50.5
[1]
PU-FB9-C
20
0.5
60
813
53.8
20
19
1.4
PU-FB10-C
60
1092
27.1
60
814
34.4
20
802
38.6
PU-FB11-C
20
900
44.7
20
864
37.9
20
14
0.9
PU-W-FB1-C
60
740
34.0
60
535
24.8
20
5
0.8
PU-W-FB2-C
60
1
0.5
300
718
35.0
20
1
0.5
PU-W-FB3-C
60
3
0.5
300
8
1.5
[1]
20
1.0
PU-W-FB4-C
60
2
0.7
300
3
0.3
20
5
0.6
PU-W-FB5-C
60
14
0.6
[1]
300
0.7
20
1
1.7
PU-W-FB6-C
60
2
0.4
300
5
0.5
20
437
42.0
frPU-C
20
391
35.4
20
489
50.8
20
571
67.6
frPU-W-C
20
579
56.5
20
600
71.7
[1]
Notes:
Weight data not collected
[2]
Could not calculate due to absence of weight data
PU-C
Total Heat
(MJ)
0.000
13.030
11.890
14.387
15.732
16.629
20.057
0.052
18.839
18.879
0.005
17.085
19.351
0.018
19.055
0.134
23.242
17.990
17.848
20.709
19.254
0.106
14.934
11.710
0.029
0.014
15.339
0.013
0.016
0.129
0.007
0.037
0.001
0.072
0.054
0.067
0.006
0.004
0.026
8.571
8.985
11.198
12.191
10.017
11.230
Heat of
Combustion
(MJ/kg)
0.0
19.0
21.5
22.1
22.9
22.4
[2]
10.4
22.9
18.4
1.7
18.8
[2]
[2]
23.4
7.1
21.3
22.1
22.3
23.0
22.3
7.6
20.2
21.9
5.8
14.0
21.4
13.0
5.3
16.1
[2]
18.5
0.3
14.4
3.9
[2]
6.0
2.0
5.2
19.6
23.0
22.9
21.4
17.3
18.7
P. 83
Figure 81: Peak heat release rate of mock-up assembly experiments. Error bars are SD for the mean of
repeated exposures.
Figure 82: Total heat release for mock-up assembly experiments. Error bars are SD for the mean of repeated
exposures.
P. 84
Figure 83: Heat of combustion for mock-up assembly experiments. Error bars are SD for the mean of
repeated exposures.
It was observed that the elastic flat barriers tended to compress the cushions edges resulting in
rounded edges and flat barriers with less drape tended to give the cushions a “stiffer-look”. These
observations were not noted to influence fire growth.
Influence of Polyester Wrap
The additional fuel load imparted by the layer of polyester wrap on the foam samples was found
to impact heat release rates and weight loss for both the untreated and flame retardant treated
foam samples (PU-W-C vs. PU-C, frPU-W-C vs. frPU-C). Heat release rate profiles for samples
with and without the polyester wrap appear to be similar with peak heat release rates observed
approximately 165 s after ignition for the untreated foam samples, Figure 84, and 275 s for the
flame retardant treated foam samples, Figure 85. The average peak heat release rate observed for
untreated foam samples incorporating the polyester wrap (PU-W-C) was approximately 8 %
greater than the samples without the polyester wrap (PU-C) but approximately 50 % greater for
the flame retardant treated foam based assemblies. The total heat release for both foam types was
15 to 20% greater when the polyester wrap was included in the samples.
More interestingly, a longer exposure period was needed to achieve self-sustained flaming in the
untreated foam combination (PU-W-C) than the samples incorporating the polyester wrap (PUW-C). This behavior was not, however, observed for the flame retardant treated foam samples.
Open flame burn duration was not impacted by the polyester wrap for either foam type.
P. 85
Figure 84: Polyester wrap effect on heat release rate profiles for PU foam based mock-up assemblies.
Figure 85: Polyester wrap effect on heat release rate profiles for frPU foam based mock-up assemblies.
P. 86
Influence of Flame retardant Treated Foam
Comparison of the untreated foam to flame retardant treated foam mock-up assemblies (PU-C vs.
frPU-C) reveals that the flame retardant treated foam specimen achieved self-sustained flaming
conditions with a shorter ignition burner exposure time, grew in intensity at a slower rate, and
burned for a longer duration, Figure 86. The average peak heat release rate of the frPU samples
was 45 % lower and the average total heat release was 23 % lower. This combustibility response
for flame retardant treated foam assemblies is consistent with TGA observations of initial
degradation occurring at a lower temperature for flame retardant treated materials than for
corresponding untreated materials.
Mock-up assemblies of both foam types covered in polyester wrap (PU-W-C vs. frPU-W-C)
attained self-sustained flaming with a 20 s burner exposure. Heat release rate growth was slightly
slower for the flame retardant treated foam mock-up assemblies and the average peak heat
release rate was 24 % lower, Figure 87. Burn duration for the two sample assembly types were
comparable resulting in the flame retardant treated foam based assemblies having an average
total heat release 28 % lower than that of the untreated foam assemblies.
The flame retardant treated foam in both sets of mock-up assemblies, with and without polyester
wrap, exhibited less consumed weight than the untreated assemblies.
Figure 86: Comparison of heat release rates for polyurethane foam and fire-retardant treated foam mock-up
assemblies.
P. 87
Figure 87: Comparison of heat release rates for polyester wrap covered polyurethane foam and fire-retardant
treated foam mock-up assemblies.
Influence of High-Loft Barriers
Four of the five high-loft barrier assembly combinations (FB7-10) survived the 20 s ignition
exposure that was sufficient to consume the polyester wrap assembly combination (PU-W-C).
However, these four barrier assembly combinations were consumed from 60 s exposures. The
fifth high-loft barrier assembly combination (FB11) was consumed from a 20 s exposure.
Once ignited, regardless of the ignition exposure duration, the high-loft barrier assemblies
burned for 500 to 1600 s longer (FB9 and FB7 respectively) than for the polyester wrap
assembly combination. Heat release rate growth was significantly slower for the high-loft barrier
assembly combinations and the average peak heat release rate was 40 to 66 % lower. Heat
release rate measurements for the five high-loft barrier clad foam samples are plotted alongside
the polyester wrap covered foam samples in Figure 88 through Figure 92.
P. 88
Figure 88: Comparison of heat release rates for polyester wrap covered polyurethane foam and high-loft fire
barrier 7 covered foam mock-up assemblies.
P. 89
P. 90
Influence of Flat Barriers
All of the six flat barrier assembly combinations (FB1-6) survived the 20 s ignition exposure that
was sufficient to consume the polyester wrap assembly combination (PU-W-C). Ignition
exposure beyond a 20 s exposure and subsequent combustibility tended to fall along barrier
technology. One para-aramid blend barrier assembly combination (FB1) was consumed from a
60 s exposure while the other para-aramid blend barrier assembly combination (FB2) survived a
60 s exposure but not a 300 s exposure. Sample burn durations for the two para-aramid barrier
combinations were extended by 1210 and 800 s for FB1 and FB2 respectively. The other four
flat barrier assembly combinations all survived a 300 s ignition source burner exposure to selfextinguish in less time than the polyester wrap assembly combination samples were consumed.
Heat release rate growth for the two para-aramid barrier assembly combinations that were
consumed was significantly slower than the assemblies without the barrier, Figure 93 and Figure
94. Peak heat release rates were attained more than 600 s longer and 66 and 59 % lower. Heat
release rates measured for the four other flat barrier assembly combinations are plotted alongside
the polyester wrap covered foam samples in Figure 95 through Figure 98.
P. 91
Figure 93: Comparison of heat release rates for polyester wrap covered polyurethane foam mock-up
assemblies with and without flat fire barrier 1.
P. 92
P. 93
P. 94
ANALYSIS
Ignitability and Self-Sustained Combustion
The same cover fabric was the initial exposed surface in all of the samples. If the cover fabric is
the sole, or dominant, source of the volatilized gases that are initially ignited, then all of the
sample combinations should have the same ignitability. Given the broad range of observed
ignition times for the various combinations of foams, barriers, and wraps, it is clear that the
internal material components were a factor in sample ignition. The internal material components
may chemically alter the combustion reaction kinetics and/or physically interfere with the
production of the combustible gases. Combustion kinetics can be interfered through the release
of chemically active species that create competing chemical reactions to the combustion reaction.
Physical interferences include limiting heat transfer to internal components thereby retarding
formation of volatilized combustible gases (i.e. a thermal barrier), a physical barrier to transport
of the volatilized combustible gases from the interior components to the combustion region, and
increased thermal mass that would take longer to heat and volatilize.
In the mock-up experiments, ignitability and self-sustained combustion was assessed by whether
or not the sample was consumed from a given ignition exposure duration. The fabric covered
untreated foam (PU-C) required a longer ignition exposure duration to fully consume the sample
than the covered flame retardant treated foam (frPU-C). The shorter exposure duration necessary
for ignition and self-sustained combustion of the flame retardant treated foam samples is
consistent with observations for the same combination of materials in Task 3 – Material
Combination Combustibility Experiments and the use of flame retardants that chemically
interfere with the combustion reaction such as the chlorinated flame retardants detected in Task 2
– Characterization of Sample Materials.
Including additional components between the foam and the exposed cover fabric will act as a
physical barrier to heat and mass transfer and sometimes also act chemically depending upon the
chemistry of the added component material.
The observed reduction in the necessary ignition exposure duration for the polyester wrap clad
foam (PU-W-C vs. PU-C) is counter intuitive if the polyester wrap acted as a physical barrier to
ignition and maintaining self-sustained combustion. Instead it appeared that the loft of the
polyester wrap created an air “channel” or “gap” between the cover fabric and the underlying
foam that facilitated flame attachment and sustained combustion in the two vertically oriented
cushions. This behavior could not be assessed for the flame retardant treated foam samples
(frPU-C and frPU-W-C) because both sample sets ignited and sustained combustion for the
shortest ignition exposure duration utilized.
Like the polyester wrap samples, PU-W-C, the cotton-viscose-rayon blend high-loft samples,
PU-FB11-C, were all consumed by the shortest ignition exposure duration utilized. This behavior
would suggest that any hindrance provided by the barrier to ignition and self-sustained
combustion in the vertical orientation were exceeded by the air “channel”/“gap” created by the
barrier loft between the cover fabric and the underlying foam.
The ignition flame duration required for ignition and self-sustained combustion of the high-loft
barrier FB7-10 wrapped samples was longer than that of the polyester wrap clad sample (PU-WThis Report cannot be modified or reproduced, in part, without the prior written permission of Underwriters Laboratories Inc.
P. 95
C) suggesting that the technologies used in these barriers did hinder ignition/self-sustained
combustion more than the air “channel”/“gap” created by the barrier loft enabled. These results
are consistent with the longer ignition times observed in the respective combination of materials
in Task 3 – Material Combination Combustibility Experiments.
Flat fire barriers (FB1-6) were not expected to act as a thermal barrier as much as a physical
and/or chemical barrier to ignition by virtue of their thickness. All of the flat barrier sample
combinations required longer ignition flame durations for ignition and self-sustained combustion
than the equivalent barrier-less sample (PU-W-C). This behavior is evidence of the barriers being
a hindrance to ignition/self-sustained combustion by physical and possible chemical
mechanisms. Placement of the flat barrier adjacent to the cover fabric was not observed to lead to
the formation of an air “channel”/“gap” under the cover fabric as observed for the previously
described high-loft barriers and polyester wrap sample combinations. In addition to being a
physical barrier, the four best performing barriers (FB 3-6) contained chemicals known to
interfere with combustion kinetics – organophosphate flame retardants, chlorinated paraffin, and
antimony oxide in FB3 and PVC formulation of FB4-6 (Task 2 – Characterization of Sample
Materials). As with the high-loft barrier samples, the results for the flat fire barriers are
consistent with the longer ignition times observed in the respective combination of materials in
Task 3 – Material Combination Combustibility Experiments.
These results are not unexpected when considering placement of the flame retardant treated
component relative to the cover fabric. In the case of the flame retardant treated foam samples
(frPU-W-C), the flame retardants are initially masked by the combustible polyester wrap
whereas in the fire barrier samples (high-loft and flat barrier), the flame retardants are adjacent to
the exposed cover fabric.
Combustion Duration and Intensity
Once ignition and sustained flaming occurs, burn intensity and duration become limited by the
diffusion rate of volatilized combustible gases to the mixed air-fuel flame region. Barriers more
effective at inhibiting the transport of volatilized gases, either by retarding the rate of
volatilization, hindering diffusion, or via chemically competitive reactions, will be more
effective at retarding combustion and therefore reducing burn intensity. Correspondingly the
burn duration will be extended provided the reduced burn intensity remains greater than the
critical flux for propagation. Should the burn intensity drop below a critical flux for propagation,
flaming combustion will cease.
The polyester wrap impacted the untreated and flame retardant treated foam samples differently
(PU-W-C and frPU-W-C respectively). For the untreated fabric covered foam samples (PU-C
and frPU-C), the initial rate of fire growth was similar to that of the samples with the polyester
wrap. One of the polyester wrap samples lasted for the same length of time as the samples
without the wrap, but the other polyester wrap samples lasted 300 s to 375 s longer. After
evaluating the fabric covered flame retardant treated foam samples with and without the
polyester wrap, it was found that the polyester wrap did not significantly impact the initial fire
growth rate or duration of any of the samples. The samples with the wrap had higher peak release
rates than the corresponding foam only samples. The average peak heat release rate was 8 %
P. 96
higher than the fabric covered untreated foam and 50 % higher for the fabric covered flame
retardant treated foam.
The impact of the flame retardant treatment on foam was apparent in the mock-up experiments
when including polyester wrap in the samples (PU-W-C vs. frPU-W-C) and not including
polyester wrap (PU-C vs. frPU-C). The fabric covered flame retardant treated foam samples
(frPU-C) showed a slower rate of fire growth and longer burn duration than the corresponding
untreated samples (PU-C). The flame retardant treated foam samples burned 150 s to 360 s
longer and had an average peak heat release rate of 45 % less than the untreated foam samples.
Including the polyester wrap, the flame retardant treated foam samples (frPU-W-C) reduced the
average peak heat release rate by 28 % and the fire durations.
Some of the high-loft barrier sample fires and most of the flat barrier sample fires selfextinguished without consuming the sample. The behavior of the fires that progressed until the
sample was fully consumed was similar to that described for the fabric covered flame retardant
treated foam fires (frPU-W-C). The durations of the high-loft barrier fires were 500 s to 1600 s
longer than the fabric covered polyester wrap and foam (PU-W-C) fires and the flat barrier fires
were 800 s to 1210 s longer than the fabric covered polyester wrap and foam (PU-W-C) fires.
The average peak heat release rates from the high-loft fire barrier samples were 40 % to 66 %
less and from the flat fire barrier samples were 59 % to 66 % less than the average peak heat
release rates from the fabric covered polyester wrap and foam samples (PU-W-C).
The trends of these results are consistent with those observed for the Task 3 – Material
Combination Combustibility Experiments.
SUMMARY
The three investigated fire mitigation approaches (substitution of untreated foam with flame
retardant treated foam, substitution of polyester wrap with high-loft fire barrier, and inclusion of
a flat fire barrier between the cover fabric and polyester wrap) demonstrated on a mock-up level
some degree of reduction in ignitability and/or flammability as characterized by the ignition
exposure time, burn duration, and peak heat release rates, total heat release, and heat of
combustion:
1. Substitution of TB 117 flame retardant treated foam (frPU) in place of untreated foam (PU):
 Flame exposure duration necessary to achieve self-sustained flaming and sample
consumption was reduced (from 60 s to 20 s)
 Intensity of the fires was reduced by an average of 45 %
 Fire duration was extended by 150 s to 360 s
2. Substitution of high-loft fire barrier (FB7 to 11) in place of polyester wrap (W):
 Flame exposure time was the same or extended (from 20 s to 20-60 s)
 Intensity of the fires was reduced by an average of 40-66 %
P. 97
3. Inclusion of a flat fire barrier (FB1 to 6) between the cover fabric and polyester wrap54:
 Flame exposure time was the extended (from 20 s to 60-300 s)
 Intensity of the fires was reduced by an average of 59-66 %
Overall, the flat barriers (FB1-6) performed better than the TB 117 foam (frPU), polyester wrap
(W), and high-loft barriers (FB7-11). Flat barriers FB3-6 were the only samples that were not
consumed by the fires from 20 s, 60 s, or 300 s flame exposure.
In some of the experiments, the fire spread through the barrier seam. Barrier seam integrity is
critical to prevent a breach between the different pieces of the mock-up.55
54
The fires tested did not consume all of the mock-ups. The data provided is for the mock-ups that were consumed.
Seam integrity has also been observed to be critical in open-flame compliance testing of mattresses as evidenced
by mattresses constructed identically except for the seams construction exhibited significantly different results.
55
P. 98
TASK 5 – FULL-SCALE FURNITURE COMBUSTIBILITY
EXPERIMENTS
The combustibility of single seat upholstered chairs exposed to an open flame ignition source
was characterized to assess performance of full-scale furniture and to investigate the applicability
of the results from mock-up tests in Task 4 – Mock-Up Assembly Combustibility Experiments.
Chairs were constructed from four combinations foam, polyester wrap, barrier material, and
cover fabric evaluated in Task 4 – Mock-Up Assembly Combustibility Experiments. The ignition
point was varied to assess its impact on fire growth and size.
SAMPLES
Single seat upholstered chairs were based on hard wood frames with metal sinuous ‘S’ springs,
jute webbing, burlap, and arm-front pleats made from the cover fabric, Figure 99. Interior
components were stapled to the wood frame and cover fabric was affixed with metal tacktite tack
strips. The weight of the frame assemblies was approximately 17.4 kg.
Figure 99: Single seat upholstered chair frame.
The chairs had loose seat and back cushions and padded armrests. Cushions were based on a 102
mm (4 in.) thick foam core wrapped in the respective component materials and inserted into the
cover fabric case. Cover fabric case seams were sewn with Size 69 bonded nylon thread. The
armrests were padded with the respective 51 mm (2 in.) thick foam and covered in either
polyester wrap or high-loft barrier FB8 such that it was stapled to the underside of the armrest,
wrapped over the armrest from the outside to the inside and extended down to below the decking
where it was stapled to the frame. Frame exterior components (burlap, polyester wrap, high-loft
barrier, decking, cover fabric, and dustcover) were affixed to the frame by staples. Pictures of the
chairs at various stages of construction are presented in Figure 100.
P. 99
Foam padded armrests (Chair 1-4)
Foam padded armrests (Chair 1-4)
High-loft barrier over foam padded armrest
(Chair 3 & 4)
Barrier FB3 being installed on exterior
(Chair 4)
Synthetic Accord dustcover (Chair 1-3)
Barrier FB3 as dustcover (Chair 4)
Figure 100: Furniture at different stages of construction.
Four combinations of materials were evaluated based on performance results observed in Task 4
– Mock-Up Assembly Combustibility Experiments. Experiment sample descriptions for the four
evaluated chair material variations are presented in Table 25.
P. 100
Table 25: Single seat upholstered chair experiment sample descriptions.
Experiment Sample Frame Cover Elements (from frame to exterior)
Back & Seat Cushions
Chair 1 (Baseline)
PU-W-C
Underside: synthetic Accord dustcover
Seat: burlap, polyester wrap (W), decking (D)
Inside back: burlap, medium weight (4-5 oz)
decking, polyester wrap (W), cover fabric (C)
Inside arm: burlap, PU foam, polyester wrap (W),
cover fabric (C)
Outside arm & back: medium weight (4-5 oz)
decking, polyester wrap (W), cover fabric (C)
PU-W-C
(PU foam wrapped in
polyester wrap and encased
with cover fabric)
Chair 2 (FR foam)
frPU-W-C
Same as Chair 1 except frPU foam substituted on
the arm & interior side
frPU-W-C
(same as Chair 1 substituting
frPU foam)
Chair 3 (High-loft
barrier clad foam)
PU-FB8-C
Same as Chair 1 except high-loft barrier FB8
substituted for polyester wrap on inside arm
PU-FB8-C
(same as Chair 1 substituting
high-loft barrier FB8)
Chair 4
(Full barrier clad)
PU-FB3/FB8-C
Underside: flat barrier FB3
Seat: burlap, polyester wrap (W), flat barrier FB3,
decking (D)
Inside back: burlap, medium weight (4-5 oz)
decking, polyester wrap (W), flat barrier FB3,
cover fabric (C)
Inside arm: burlap, PU foam, polyester wrap (W),
flat barrier FB3, cover fabric (C)
Outside arm & back: medium weight (4-5 oz)
decking, polyester wrap (W), flat barrier FB3,
cover fabric (C)
PU-FB8-C
(same as Chair 3)
Samples were conditioned in air at a temperature greater than 18 °C (65 °F) and less than 25 °C
(77 °F) and a relative humidity less than 55 percent for a minimum of 72 hours prior to testing.
Note that these temperature and humidity conditions are consistent with the Consumer Product
Safety Commission’s 16 CFR Part 1633 Standard for the Flammability (Open Flame) of
Mattress Sets; Final Rule and exceed the duration requirements. Post-conditioning samples
weights are listed in Table 26.
Table 26: Single seat upholstered chair experiment sample mass.
Experiment
Sample
Chair 1
(PU-W-C)
Chair 3
(PU-FB8-C)
Ignition
Location
Corner
Seat/Back
Back Bottom
Corner
Seat/Back
Back Bottom
Chair Mass
(kg)
23.6
23.1
23.6
23.8
24.1
24.3
Experiment
Sample
Ignition
Location
Corner
Seat/Back
Back Bottom
Corner
Chair 4
Seat/Back
(PU-FB8/FB3-C)
Back Bottom
Chair 2
(frPU-W-C)
Chair Mass
(kg)
23.4
24.0
24.1
23.9
23.5
24.3
P. 101
EXPERIMENTAL
Combustibility of the chairs was evaluated on a load cell in a room oxygen consumption
calorimeter (UL Test Cell A). A noncombustible deck board was placed on the load cell below
the chairs to catch materials that melted and fell away.
Chairs were ignited using a 20 second application of the match flame equivalent ignition source,
BS 5852 source 1 (gas flame)56, to one the three ignition locations displayed in Figure 101 and
listed below:
1. Corner: Interior corner formed by the arm rest, and seat and back cushions
2. Seat/Back: Midpoint of the crevice created by the intersection of the seat and back cushions
3. Back Bottom: Bottom of back of chair near the chair leg
Figure 101: Ignition locations for furniture combustibility experiments of single seat upholstered chairs.
RESULTS
The 20 second exposure to the ignition burner flame was sufficient to ignite all of the chairs at
the corner and seat/back locations. Ignition at the back bottom location was found to be
considerably more challenging than the cushions and required multiple ignition attempts as noted
below.
Chair 1 – PU-W-C
Attempt 1: 20 s exposure at right leg
Chair 2 – frPU-W-C
Attempt 1: 20 s exposure at right leg, self-extinguished approximately 20 s later
Attempt 2: 10 s exposure at Attempt 1 location
Chair 3 – PU-FB8-C
56
P. 102
Attempt 1: 20 s exposure at right leg, consumed underside dustcover from bottom resulting
in flaming droplets on the test deck, self-extinguished approximately 5 min after
ignition;
Attempt 2: 30 s exposure at left leg, self-extinguished approximately 25 s later
Attempt 3: 30 s exposure at Attempt 1 location
Chair 4 – PU-FB3/FB8-C
Attempt 1: 20 s exposure at right leg, self-extinguished 36 s later
Attempt 2: 30 s exposure at left leg, self-extinguished 8 s later
Attempt 3: 20 s exposure at center of bottom edge, self-extinguished 24 s later
Attempt 4: 25 s exposure at Attempt 1 location, flaming droplets on the test deck, selfextinguished 9:15 later
Observed heat release rates and sample mass loss for the four chair constructions ignited at the
three locations are plotted in Figure 102 and Figure 103 respectively. Although details cannot be
clearly seen, three distinct fire growth behavior trends can be distinguished:
 Rapid development and high peak heat release rate
 Delayed development and moderate peak heat release rate
 Limited burning
Figure 102: Heat release rate profiles for upholstered chair fire experiments.
P. 103
Figure 103: Mass loss profiles for upholstered chair fire experiments.
Fire progression for three of the chair fire experiments exhibiting the three distinct fire growth
behavior categories are depicted in the following three series of time-lapsed pictures, Figure 104
through Figure 106.
P. 104
60 seconds
120 seconds
180 seconds
240 seconds
300 seconds
343 seconds (Peak HRR)
403 seconds (Peak HRR + 60 s)
Figure 104: Fire progression for chair exhibiting rapid development and high peak heat release rate.
P. 105
60 seconds
150 seconds
300 seconds
480 seconds
Figure 105: Fire progression for chair exhibiting delayed development and moderate peak heat release rate.
P. 106
60 seconds for Attempt #4
120 seconds
Figure 106: Fire progression for chair exhibiting limited burning.
Peak heat release rates for the twelve trials are plotted in Figure 107. The burn duration
associated with the peak heat release rate is tabulated in Table 27 along with the corresponding
total heat release and sample weight loss.
P. 107
corner
seat/back
back bottom
Figure 107: Furniture calorimeter peak heat release rates.
Table 27: Furniture combustion conditions at peak heat release rate.
Experiment
Sample
Ignition
Location
Corner
Seat/Back
Back Bottom
Corner
Chair 2
Seat/Back
(frPU-W-C)
Back Bottom
Corner
Chair 3
Seat/Back
(PU-FB8-C)
Back Bottom
Corner
Chair 4
Seat/Back
(PU-FB8/FB3-C)
Back Bottom
Chair 1
(PU-W-C)
Heat Release
Rate
(kW)
1268
1397
1367
1073
1146
1380
382
427
444
190
214
3
at Peak Heat Release Rate (PHRR)
Total Heat
Weight Loss Burn Duration
Release
(%)
(s)
(MJ)
141
29.5
382
141
28.1
343
95
20.5
546
130
29.8
321
137
31.2
362
148
33.1
596
167
39.1
1151
102
22.0
1892
68
17.3
640
103
23.4
1090
10
2.3
504
1
0.7
581
Fire growth rate for the four chair constructions and three ignition locations is depicted in Figure
108 by the burn duration associated with reaching, 100, 200, 500, 1000 kW and the peak heat
release rate. Consumed sample weight loss corresponding to these points is plotted in Figure 109.
Measured heat release rates and consumed sample weights for the twelve experiments are plotted
in Appendix B: Full-Scale Furniture Heat Release Rate and Mass Loss Plots.
corner
P. 108
seat/back
back bottom
Figure 108: Fire growth rate for furniture calorimeter experiments. Measured peak heat release rates (kW)
are listed above the respective experiments.
corner
seat/back
back bottom
Figure 109: Weight loss rate for furniture calorimeter experiments.
P. 109
ANALYSIS
Fire growth behavior of the chairs was influenced by the furniture component materials and the
ignition location.
Influence of Ignition Location
The impact of ignition location was observed in the ease of ignitability and fire growth behavior.
The backside location was more difficult to ignite than the cushions (interior corner and
seat/back) due to differences in the materials, most notably the wood frame structure member
and the absence of foam. The difference in the material properties of the foam and wood impacts
the ignitability and incipient fire growth stage in three respects: (1) wood has a greater critical
flux for ignition than the foam (~ 12 kW/m2 reported for maple57 and 7 kW/m2 for non-FR
furniture grade polyurethane foam58), (2) wood has a greater thermal mass (heat capacity × mass)
than the foam59, and (3) wood has a greater heat conductivity than foam60. As a net result,
ignition and sustained flaming combustion of the backside location requires a greater amount of
heat input.
Ignition location influenced the fire growth behavior to varying degrees. Fire propagation for
chairs ignited at foam bearing portions, i.e. interior corner and seat/back, was similar whereas
ignition of the chair backside resulted in dramatically different fire propagation.
Fire propagation for chairs ignited at the interior corner initially occurred upward along the
vertical intersection of the arm and back cushion and then spread laterally across the arm and
back cushion and radially outward on the seat cushion to engage the far arm. Fire propagation for
chairs ignited at the seat/back location initially occurred up the back cushion and then spread
laterally across the back cushion and radially outward on the seat cushion to engage both arms at
approximately the same time. Fire propagation for chairs ignited at the backside location initially
occurred up the backside between the decking and the cover fabric, penetrating the upper frame
cavity to the front side of the frame, engaging the back cushion and simultaneously spreading to
the two arms and seat cushion.
The consequence of the ignition location-induced fire growth behaviors on the heat release rate
can be seen in Figure 110 through Figure 113 for Chairs 1 to 4. For the baseline chairs, PU-W-C,
and the frPU-W-C chairs (Chair 1 & 2), the corner, seat/back, and back bottom ignition locations
resulted in fires with similar behavior – rapid fire growth and a high peak heat release rate. The
only difference being that the wood at the back bottom location delayed the spike in heat release
rate by 200 s. For the PU-FB8-C chairs (Chair 3), the first peak heat release rate happens from
the back bottom ignition. The back bottom ignited fire peaked early at about 600 s while the
corner ignited fire took almost an additional 600 s to reach its peak heat release rate. The
seat/back ignited fire grew at a similar rate to the back bottom ignited fire, but was delayed about
57
Spearpoint, M.J., Predicting the Ignition and Burning Rate of Wood in the Cone Calorimeter Using and Integral
Model (NIST GCR 99-775), National Institute of Standards and Technology (1999)
58
Fernando, A., Leonard, J., Webb, A., Bowditch, P., and Dowling, V., Experimental Derivation of Material
Combustion Properties for Flame Spread Models, pp.315-326 in Proc. Fire and Materials 2001 Conf., Interscience
Communications Ltd., London (2001).
59
Drysdale, D.D. An Introduction to Fire Dynamics, 2nd ed., p. 33, (1999).
60
Drysdale, D.D. An Introduction to Fire Dynamics, 2nd ed., p. 33, (1999).
P. 110
1100 s. Chair 4, which coupled the PU-FB8-C cushions with a flat fire barrier FB3 on the chair
exterior sides, self-extinguished after multiple attempts to ignite the back bottom of the chair.
The corner and seat/back ignited chairs did fully burn. The corner ignited fire initially grew
faster than the seat/back ignited fire, but did not reach its peak heat release rate until 500 s after
the seat/back fire peaked. Table 28 summarizes the effect the change in ignition location impacts
the peak heat release rate.
Figure 110: Heat release rate results for Chair 1 (baseline) ignited at in tested locations.
P. 111
Figure 111: Heat release rate results for ignition of Chair 2 (FR foam) in various locations.
Figure 112: Heat release rate results for ignition of Chair 3 (High-loft barrier clad foam) in various locations.
P. 112
Figure 113: Heat release rate results for ignition of Chair 4 (Full barrier clad) in various locations.
Excluding the Chair 4 sample ignited at the back bottom and self-extinguished, the standard
deviations of all of the samples are within at most 13% of the average peak heat release rate.
This shows that the ignition location has a minimal effect on the peak heat release rate of the
samples that did not self-extinguish.
Table 28: Average peak heat release rate and standard deviation for each chair type
Standard Deviation
Average PHRR
(kW)
(kW)
(% of Average)
Chair 1 (PU-W-C)
1344
68
5
Chair 2 (frPU-W-C)
1200
160
13
Chair 3 (PU-FB8-C)
418
32
8
[1]
Chair 4 (PU-FB8/FB3-C)
202
17
8
[1]
Note:
Data excludes the back bottom ignited sample that self-extinguished
Experiment Sample
The peak heat release rates are minimally impacted by the change in the ignition location (except
in the case where the sample self-extinguished). Generally, the fire behavior was unchanged as
well. The differences that occurred were when the fire growth rate began to initially increase
quickly and the peak heat release rate occurred.
These observations are similar to other research on ignition location effects. Mittler and Tu61
investigated ignition location effect on twelve chairs and demonstrated that measured peak heat
61
Mittler, H.E. and Tu, K.M. Effect of Ignition Location on Heat Release Rate of Burning Upholstered Furniture.
NISTIR 5499, National Institute of Standards and Technology, United States (1994).
P. 113
release rates were within 10 % regardless of the four investigated ignition locations and chairs
ignited from the back took longer to reach their peak heat release rate than chairs ignited on the
center of the cushion.
More recently ignition location has been found to be a factor on larger furniture pieces.
Janssens62 found that the peak heat release rate was greater for three-seat, cotton fabric and highdensity polyurethane foam sofa mock-ups ignited in the center cushion versus next to the arm
(using CA TB 133 burner flame). Fire growth rates, however, were similar for the initial
approximately 130 seconds after which the sofa mock-up ignited at the center cushion continued
to increase whereas the sofa mock-up ignited at the arm burned at a relatively steady heat release
rate for another 240 seconds or so.
Influence of Furniture Component Materials
Some of the utilized component materials used in the furniture pieces were found to have a more
significant effect on fire propagation than others.
Comparison of results for chairs constructed with the two different foam types, PU (Chair 1) and
fire-retardant treated foam frPU (Chair 2), reveals that the flame retardant treated foam chairs
exhibited approximately 15 % lower peak heat release rates when the cushions were directly
ignited and comparable peak heat release rates when ignited from the back side (Table 27). The
fire growth rate and duration to grow from 100 kW to 1000 kW, however, are within 50 seconds
regardless of ignition location. This last point is significant when put into context of room
flashover – NFPA 286 identifies flashover for a 2.44 × 3.66 × 2.44 m (8 × 12 × 8 ft) room with
0.78 m (30.75 in.) wide by 2.02 m (79.5 in.) high door opening as 1000 kW.63 Collectively these
results show that the benefits of the flame retardant treatment foam utilized in this study are
overwhelmed by the ignition source and application duration employed in this study and does not
result in a practical benefit to occupants with respect to occupant safety and egress time.
Substitution of the polyester wrap on the cushions and arm rests with high-loft barrier FB8
(Chair 1 vs. Chair 3) was found to reduce the peak heat release rate by approximately 70 % to
less than 500 kW. Correspondingly the fire growth rate from 100 to 200 kW was found to be
extended by 120 to 480 seconds depending on ignition location. Based on these results it would
not be unreasonable to expect the high-loft barrier wrapped foam chair style to extend tenable
and survivable conditions in residences thereby improving occupant life safety.
Chair styles 1, 2, and 3 had the same components on the frame back; therefore, differences in fire
propagation rates when ignited at the back are attributable to the cushion and arm rest
components. Fire growth rates were similar for the three chair styles while the fire was limited to
the back side of the frame. Correspondingly the time for the heat release rate to reach 100 kW
ranged between 364 and 470 seconds. Once the flames penetrated upper back of the chair frame
to engage the cushions, however, differences in the fire growth rate stemming from the cushion
and arm rest components became apparent. Heat release rates for the polyester wrapped foam
62
Janssens, M. Reducing Uncertainty of Quantifying the Burning Rate of Upholstered Furniture. Southwest
Research Institute, United States (July 2012).
63
NFPA 286 Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth.
National Fire Protection Association, United States (2011).
P. 114
Chairs 1 and 2 rapidly accelerated in excess of 1300 kW whereas the FB8 high-loft barrier clad
Chair 3 accelerated at a more modest rate to approximately 450 kW. The reduction in peak heat
release rate and longer burn duration difference for the high-loft barrier wrapped foam chair
relative to the other two chair styles may have been in part due to the FB8’s thicker loft
providing more of a physical hindrance to the transport of volatilized gases as well as the char
forming cotton and the boric acid present in the FB8 barrier chemically interfering in the
combustion reaction. Heat release rates measured for the four chair variations are plotted in
Figure 114.
Figure 114: Heat release rate profiles for the four chair styles ignited at the back bottom.
Addition of flat barrier FB3 around the chair frame to the FB8 high-loft barrier wrapped
cushions and arm rests (Chair 4) was found to further reduce the peak heat release rate by 50 %
(approximately 85 % less than Chair 1) to less than 225 kW when ignited on the cushions; the
peak heat release rate was less than 10 kW when ignited on the back side. Based on these results,
significant improvement in life safety would be reasonable to expect for this furniture style.
Chair styles 3 and 4 used the same cushions and same frame components with the exception of
the added flat barrier FB3 on the frame exterior in Chair 4. Therefore, differences in fire
propagation rates when ignited on the cushions are attributable to the barrier on the frame
exterior. Heat release rate profiles for the two chairs ignited at the interior corner are remarkably
similar, Figure 115. The second peak appears to correspond to flame penetration into the back
cushion and breaching of the sides below the arm rests. The breaching of the sides provided
another air flow path to the back cushion. Flames were found to penetrate the side breaches in
Chair 3 but not Chair 4 suggesting the underlying glass fiber weave in the barrier was a sufficient
P. 115
physical barrier to retard air flow to the chair seating portion. This visual assessment is further
corroborated by the smaller peak heat release rate associated with the second peak. Similar
behavior was observed for the chairs ignited at the seat/back location.
Figure 115: Heat release rate profiles for the two barrier clad chair styles ignited at the interior corner.
Comparison of Full-scale Furniture Experiments to Mock-Up Assembly Experiments
The furniture pieces were considerably larger, geometrically more complex, contain a wider
variety of components and component materials in varying thicknesses and arrangements, and
construction elements not represented in the mock-up arrangements. Consequently the size of the
furniture fires was expected to be considerably larger than that of the mock-up arrangement fires
on the corresponding foam/barrier/polyester wrap components. Despite these differences, the
mock-up experiments provided insight into the burning behavior of full-scale furniture.
The three cushion mock-up arrangements resembled the furniture interior corner formed by the
arm, seat and back cushions. The resemblance was both in terms of physical geometry (one
horizontal surface and two orthogonal vertical surfaces) and components. These similarities
suggest that the early stage of fire growth in the chairs ignited at the interior corner (before the
fire size exceeds the size of the mock-up arrangements) should be similar to the corresponding
mock-up arrangements. Plots of the three component arrangements used in the furniture
cushions, PU-W-C (Chair 1), frPU-W-C (Chair 2), and PU-FB8-C (Chairs 3 and 4), are plotted
alongside corresponding Task 4 mock-up experiments in Figure 116 through Figure 118.
P. 116
Figure 116: Heat release rates for PU-W-C chair (interior corner ignition) and mock-up experiments.
Figure 117: Heat release rates for frPU-W-C chair (interior corner ignition) and mock-up experiments.
P. 117
Figure 118: Heat release rates for PU-FB8-C cushioned chairs (interior corner ignition) and mock-up
experiments.
Fire growth in the PU-W-C mock-ups and chair are virtually indistinguishable for the first c.150
seconds at which point the mock-up arrangements reach their size-limited peak heat release rate.
Initial fire growth of the chairs using the two fire resistant strategies, flame retardant treated
foam in frPU-W-C and the high-loft fire barrier in PU-FB8-C, was more rapid than the
corresponding mock-ups indicating the larger chair samples to be less impacted by the fire
resistant strategy than the mock-ups. It should also be noted that the PU-FB8-C cushioned chairs
sustained self-propagating flames after a 20 second exposure to the ignition source whereas the
PU-FB8-C mock-ups did not. Thus, reduction in flammability performance of mock-ups may not
necessarily be representative of full-scale fire behavior.
Trends observed for the material combinations in the mock-up and chair experiments were
however consistent. In the mock-up experiments, the intensities of the fires were reduced by
substituting the untreated polyurethane foam for flame retardant polyurethane foam, the
polyester wrap for high-loft fire barrier FB8, and the addition of flat fire barrier FB3 (PU-W-C
vs. frPU-W-C, PU-FB8-C, and PU-W-FB3-C). The peak heat release rates for each material
combination were ordered as follows: PU-W-C > frPU-W-C > PU-FB8-C > PU-W-FB3-C. The
results of the full-scale experiments showed little difference in the peak heat release rates
between the PU-W-C and frPU-W-C chairs (Chair 1 & 2). But the peak heat release rate dropped
70 % when the wrap was replaced with FB8 (Chair 3) and 85 % when FB3 was added (Chair 4).
P. 118
The difficulty igniting Chair 4 (PU-FB8-C cushions and FB3 clad exterior sides) at the back
location and obtaining self-propagating fire growth was consistent with the results observed for
the mock-up experiments using the same fire barrier (PU-W-FB3-C) in Task 4 – Mock-Up
Assembly Combustibility Experiments in which the mock-up samples self-extinguished after
each of the 20 s, 60 s, and 300 s flame exposures.
SUMMARY
The fire performance of four different combinations of materials and the effect of varying
ignition locations was investigated using full-scale upholstered chairs. Baseline chairs (Chair 1)
were made with a non-flame retardant treated polyurethane foam covered with polyester wrap
and the cover fabric (PU-W-C). Chair 2 were constructed by replacing the untreated foam with
flame retardant treated foam (frPU-W-C) in the arms and cushions. In Chair 3, the polyester
wrap was replaced with a high-loft barrier (PU-FB8-C) in the arms and cushions. Lastly, Chair 4
was made the same as Chair 3 but also included a flat barrier under the cover fabric on all of the
chair exterior sides (FB3). The material changes affected the intensities and behavior of the fires.
Three ignition locations were evaluated for each chair type – the inside corner where the arm
meets the back and the seat cushion, middle of the seat cushion where it meets the back of the
chair, and the bottom of back of chair next to the foot of the chair. The changes in ignition
locations resulted in changes in the ignitability and time to the peak heat release rate.
1. Effect of changing ignition locations:
 20 s flame exposures were sufficient to ignite the corner and side/back location for each
of the chairs.
 The back bottom location required more than one 20 s exposure for Chairs 2-4, due to the
wood frame and absence of foam at the location
 Resulting fire intensities varied minimally; the standard deviation of was at most 13% of
the average peak heat release rate for the samples that successfully burned
 Fire behavior was unchanged for Chairs 1-3; the Chair 4 back bottom ignited fire showed
limited burning, while the fires at the other locations showed delayed development with a
moderate heat release rate
 One chair, the FB3/FB8 Chair 4 fire ignited from the back bottom, was the only chair to
show limited burning and self-extinguished
 Time to peak heat release rate varied 203 s for Chair 1, 275 s for Chair 2, 1252 s for
Chair 3, and 586 s for Chair 4
 Fire growth behavior was unchanged – rapid development with a high peak release rate.
 Average peak heat release rate was reduced by 15% for corner ignition and side/back
location, and unchanged for the back bottom ignition.
 Elapsed times for the heat release rate to reach 1000 kW (flashover) were comparable
3. Substitution of high-loft fire barrier (FB8) in place of polyester wrap (W):
 Fire growth behavior showed delayed development with a moderate heat release rate.
 Average peak heat release rate was reduced by 70 %
P. 119
4. Substitution of high-loft fire barrier (FB8) in place of polyester wrap (W) and inclusion of a
flat fire barrier (FB3) under the chair exterior side cover fabric:
 Fire growth behavior showed delayed development with a moderate heat release rate or
limited burning (depending on the ignition location)
 Ignition at the back bottom resulted in limited burning and self-extinguished without
engaging the chair cushions
 Average peak heat release rate when ignited on the cushion and consuming the sample
was reduced by 85 %
Overall Chair 4 (containing both high-loft and flat barriers) proved to be the most fire resistant in
the full-scale chair experiments, self-extinguishing when ignited at the back bottom and reducing
the peak heat release rates by more than 1000 kW to about 200 kW or less when ignited on the
cushions.
P. 120
FINDINGS
A series of fire experiments were conducted to explore the potential of commercially available
fire barrier products (interliners) and a fire-retardant treated polyurethane foam to retard and/or
reduce the fire growth rate of upholstered furniture when exposed to small open flames. While
this investigation was by no means all encompassing, particularly with regards to the flame
retardant foam and the usability of the fire barrier and foam materials for commercial production,
certain findings include:
Material Chemistry
 The investigated fire barriers utilized different technologies to impart the desired reduction in
ignitability/flammability. All of the strategies are targeted at impacting the combustion
reaction by either reducing the reaction rate or altering the reaction kinetics. Approaches
included:
o Physical hindrances to retard heat transfer (slows reaction rate)
o Physical hindrances to diffusion of volatilized gases to the diffusion flame (slows
reaction rate)
o Reactive chemistry such as charring materials to hinder heat transfer (slows reaction rate)
o Reactive chemistry such as halogenated compounds to interfere in the combustion
reaction (changes reaction kinetics)

Reactive flame retardant chemicals were observed in the flame retardant treated foam and
barriers by various analytical techniques and some specific compounds were qualitatively
identified:
o chlorinated species: PAN-PVC copolymer, chlorinated paraffins,
o organophosphates; triphenyl phosphate (TPP), tris(4-tert-butylphenyl) phenyl phosphate
(TBPP)
o chlorinated organophosphates: tris(1,3-dichloroisopropyl)phosphate (TDCPP)
o inorganic species: boric acid, antimony trioxide
Material-Level Experiments
ASTM E 1354 cone calorimeter testing provided a convenient means for repeatable, wellcontrolled evaluation of the combustibility of individual and combinations of materials.
a flat fire barrier between the cover fabric and polyester wrap) demonstrated on a material level
some degree of reduction in ignitability and/or flammability as characterized by the time to
ignition, burn duration, peak and 180s average heat release rates, total heat release, and effective
heat of combustion:
1. Substitution of TB 117 compliant foam (frPU) for regular polyurethane foam (PU) exhibited
slightly shorter burn duration.
2. Substitution of a high-loft fire barrier (FB7 to 11) for polyester wrap (W):
 Prolonged time to ignition


P. 121
Extended burn duration but at a significantly reduced combustion intensity (heat release
rates)
Reduced total heat release
3. Inclusion of a flat fire barrier (FB1 to 6) between the polyurethane foam and the cover fabric:
 Prolonged time to ignition up to twice as long
 Para-aramid blend barriers extended burn duration at a significantly reduced combustion
intensity (heat release rates)
 Flat barriers utilizing halogenated chemistries shortened burn duration and reduced
combustion intensity (heat release rates) by up to 90 %
 Reduced total heat release
Overall, incorporation of a barrier, whether a high-loft or a flat barrier, appeared to be more
effective at prolonging time to ignition and reducing heat release rates than substitution of the
TB 117 compliant foam in these calorimeter sized samples.
Despite differences in sample components, a reasonable correlation between weight loss and
effective heat of combustion was established for cone calorimeter samples.
Mock-up Experiments
The three cushion mock-up arrangement experiments provided a convenient means for assessing
the combustibility of combinations of furniture components in an increasingly complex sample
geometry than the cone calorimeter but without the need for complete furniture pieces. The
mock-up arrangement expanded fire growth potential from material-level cone calorimeter
experiments through additional fuel mass; introduction of multiple burning surfaces including
horizontal (bottom cushion and side cushion tops), vertical (back and side cushions), and
overhanging surfaces (crevices formed by seat cushion and the side cushions); re-radiation
between surfaces; opportunity for pool fire formation; and fire spread. Ignition by a match-flame
equivalent gas source was simulated a first item ignited scenario.
a flat fire barrier between the cover fabric and polyester wrap) demonstrated on a mock-up level
some degree of reduction in ignitability and/or flammability as characterized by the ignition
exposure time, burn duration, and peak heat release rates, total heat release, and heat of
combustion:
 Flame exposure duration necessary to achieve self-sustained flaming and eventual sample
consumption was shorter
 Fire duration was extended but at a significantly reduced intensity
2. Substitution of high-loft fire barrier (FB7 to 11) in place of polyester wrap (W):
 Flame exposure duration necessary to achieve self-sustained flaming and eventual sample
consumption was the same or longer
 Fire duration was extended but at a significantly reduced intensity
P. 122
3. Inclusion of a flat fire barrier (FB1 to 6) between the cover fabric and polyester wrap:
 Flame exposure ration necessary to achieve self-sustained flaming and eventual sample
consumption was extended up to 300 seconds
 Para-aramid blend barriers extended burn duration at a significantly reduced combustion
intensity (heat release rates)
 Flat barriers utilizing halogenated chemistries were not consumed by fire even after 300
second ignition flame exposures
Overall, the flat barriers (FB1-6) performed better than the TB 117 foam (frPU), polyester wrap
(W), and high-loft barriers (FB7-11).
In some of the experiments, the fire spread through the barrier seam. Barrier seam integrity is
critical to prevent a breach between the different pieces of the mock-up.
Furniture Experiments
The furniture experiments provided a means to assess the combustibility of upholstered furniture
on a system level as opposed to a component or material level. Complete furniture testing
accounted for all of the factors potentially affecting combustibility such as furniture size and
geometry, decorative features, components and component materials in varying thicknesses and
arrangements, and construction (including any construction defects). Ignition by a match-flame
equivalent gas source simulated a first item ignited scenario and offered a means for comparison
of results to the mock-up arrangements of components.
Four combinations of component materials were investigated to explore the different mitigation
approaches in single seat upholstered chairs. The chairs had hard wood frames, padded armrests,
and loose seat and back cushions. Baseline performance, Chair 1, was established using
untreated foam covered with polyester wrap. An equivalent chair in which the TB 117 compliant
foam was used instead of the untreated foam constituted the flame retardant treated foam
approach, Chair 2. Fire barriers were utilized in two variations of chairs. Chair 3 used the
untreated foam covered with high-loft barrier FB8 instead of the polyester wrap, and Chair 4 was
the same as Chair 3 but also included flat fire barrier FB3 under the cover fabric on all of the
chair exterior sides. The material changes affected the intensities and behavior of the fires.
Three ignition locations were evaluated for each chair type – the inside corner where the arm
meets the back and the seat cushion, middle of the seat cushion where it meets the back of the
chair, and the bottom of back of chair next to the foot of the chair. The changes in ignition
locations resulted in changes in the ignitability and time to the peak heat release rate.
1. Effect of changing ignition locations:
 20 s flame exposures were sufficient to ignite the corner and side/back location for each
of the chairs.
 The back bottom location required more than one 20 s exposure for Chairs 2-4, due to the
wood frame and absence of foam at the location
 Resulting fire intensities varied minimally; the standard deviation of was at most 13% of
the average peak heat release rate for the samples that successfully burned



P. 123
Fire behavior was unchanged for Chairs 1-3; the Chair 4 back bottom ignited fire showed
limited burning, while the fires at the other locations showed delayed development with a
moderate heat release rate
One chair, the FB3/FB8 Chair 4 fire ignited from the back bottom, was the only chair to
show limited burning and self-extinguished
Time to peak heat release rate varied 203 s for Chair 1, 275 s for Chair 2, 1252 s for
Chair 3, and 586 s for Chair 4
 Fire growth behavior was unchanged – rapid development with a high peak release rate.
 Average peak heat release rate was reduced by 15% for corner ignition and side/back
location, and unchanged for the back bottom ignition.
 Elapsed times for the heat release rate to reach 1000 kW (flashover) were comparable.
3. Substitution of high-loft fire barrier (FB8) in place of polyester wrap (W):
 Fire growth behavior showed delayed development with a moderate heat release rate.
 Average peak heat release rate was reduced by 70 % (~ 400 kW).
4. Substitution of high-loft fire barrier (FB8) in place of polyester wrap (W) and inclusion of a
flat fire barrier (FB3) under the chair exterior side cover fabric:
 Fire growth behavior showed delayed development with a moderate heat release rate or
limited burning (depending on the ignition location).
 Ignition at the back bottom resulted in limited burning and self-extinguished without
engaging the chair cushions.
 Average peak heat release rate when ignited on the cushion and consuming the sample
was reduced by 85 % (~ 200 kW).
The heat release rate experiments on the individual chairs clearly demonstrated that
commercially available fire barrier products (interliners) can retard the fire growth rate of
upholstered furniture exposed to small open flames, and consequently delay, or possibly even
prevent, room flashover thereby potentially reducing occupant deaths and injuries and property
damage. The investigated fire barriers were found to be significantly more effective than the
investigated fire-retardant treated polyurethane foam meeting California TB 117 performance
requirements.
Peak heat release rates measured for upholstered chairs made with California TB 117 compliant
fire-retardant treated polyurethane foam were measurably less than for furniture made without
the compliant foam. The results, however, were not meaningful when placed in context of the
potential for developing flashover conditions. It should be noted that California TB 117 only
prescribes a minimum performance level and that other compliant foam products utilizing
different flame retardant chemistries and/or concentrations may demonstrate more meaningful
results.
Overall, Chair 4 (containing both high-loft and flat barriers) proved to be the most fire resistant
in the full-scale chair experiments, self-extinguishing when ignited at the back bottom and
P. 124
reducing the peak heat release rates by more than 1000 kW to about 200 kW or less when ignited
on the cushions.
Lastly, flammability trends observed for the material combinations in the mock-up experiments
were generally consistent with those observed for the chair experiments. However, some
reductions in ignitability and flammability observed in the mock-up experiments were not as
pronounced in the chair experiments suggesting caution to be exercised when predicting fullscale fire behavior from mock-up experiments.
P. 125
IMPLICATIONS FOR POLICY AND PRACTICE
Based on the work reported herein and other published literature, the following views are
presented for consideration:
1. Fires originating from upholstered furniture have been and continue to be a serious concern
that needs to be effectively addressed.
2. Mechanisms to retard ignitability and fire growth from open flame exposure such as fire
barriers should be incorporated in upholstered furniture. However, a balanced approach that
also considers health implications and impact to the environment needs to be considered.
Flammability standard for residential upholstered furniture should embody both smoldering
and open flame exposure.
3. Compliance requirements for a residential upholstered furniture flammability standard should
be based on end product (full furniture) testing.
4. Compliance requirements for residential upholstered furniture flammability standard should
include provisions for acceptance of alternative components (component substitution).
5. Acceptance of alternative components should be plausible by simple, easy to conduct, low
cost means such as material level or mock-up level tests. Performance of the proposed
alternative components should be no worse than that of the components deemed acceptable
through end product testing.
6. A single nation-wide (or even global) program for evaluating the fire performance of
upholstered furniture would allow manufacturers to introduce products more quickly and
efficiently while establishing equivalent safety for all.
Collectively these recommendations are quite similar to the existing CPSC program for
evaluating the fire performance of mattresses (16 CFR 1632 for smoldering ignition resistance
and 16 CFR 1633 for open flame resistance).
IMPLICATIONS FOR FUTURE RESEARCH
The research reported herein expands the existing body of scientific knowledge regarding the
impact of furniture components and materials on ignitability and fire growth. There are,
however, areas that could benefit from further research. These areas include the following:
 Assessment of new fire barriers not available at the time of this investigation
 Broader study of flame retardant treated foams with regards to flame retardant chemistry and
concentration effects on upholstered furniture flammability
 Impact of filling materials other than polyurethane foam on upholstered furniture
flammability
 Combinations of flame retardant treated foam, other filling materials, and barriers
 Smoldering ignition resistance of fire barrier clad upholstered furniture
 Further refinement of small-scale predictive flammability test methods
 Assessment of furniture geometry impact on upholstered furniture flammability



P. 126
Impact of aging and use on the flammability of upholstered furniture constructed with fire
barriers and/or flame retardant-treated foams
Impact of the slower fire growth rate in upholstered furniture on the time to room flashover
Impact of the slower fire growth rate in upholstered furniture on occupant tenability and
survivability
FUNDING DISCLOSURE
All financial support for this research was funded solely by Underwriters Laboratories Inc. and
UL LLC.
P. 127
APPENDIX A: MOCK-UP ASSEMBLY TEST FRAME
The mock-up assembly test frame utilized in this work was based on the test frames specified in
BS 585264 and 16 CFR Part 163465. The test frame consists of three steel square frames
orthogonal to each other. The square frames were made of nominal 25 × 25 mm (1 × 1 inch)
steel angle 3 mm (0.125 inch) thick and securely held platforms of expanded steel mesh set 6 ± 1
mm (0.25 ± 0.05 inch) below the front face of each test frame. The expanded steel mesh was
approximately 28 × 6 mm. The horizontal square frame (“seat”) was 51 mm (2 inch) above the
noncombustible deck board. The test frame is pictured in Figure 119.
Figure 119: Mock-up test frame.
64
BS 5852 “Methods of Test for Assessment of the Ignitability of Upholstered Seating by Smouldering and Flaming
Ignition Sources”, British Standards Institute, UK.
65
16 CFR Part 1634 “Standard for the Flammability of Residential Upholstered Furniture; Proposed Rule”, US
P. 128
APPENDIX B: FULL-SCALE FURNITURE HEAT RELEASE
RATE AND MASS LOSS PLOTS
Heat release rate and mass loss rate for the four chair styles ignited in the three locations are
plotted in Figure 120 through Figure 131.
Figure 120: Heat release rate and sample mass of Chair 1 ignited at the corner.
P. 129
P. 130
Figure 124: Heat release rate and sample mass of Chair 1 ignited at the seat/back.
P. 131
P. 132
Figure 128: Heat release rate and sample mass of Chair 1 ignited at the back bottom.
P. 133
P. 134

upholstered furniture flammability

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