NIST Technical Note 1760 

Smoke Component Yields from BenchScale Fire Tests: 1. NFPA 269 / ASTM 

E 1678 

Nathan D. Marsh 

Richard G. Gann 

Jason D. Averill 

Marc R. Nyden 

 

NIST Technical Note 1760
 

Smoke Component Yields from BenchScale Fire Tests: 1. NFPA 269 / ASTM 

E 1678 

Nathan D. Marsh 

Richard G. Gann 

Jason D. Averill 

Marc R. Nyden 

Fire Research Division 

Engineering Laboratory 

December 2013 

U.S. Department of Commerce 

Penny Pritzker, Secretary 

National Institute of Standards and Technology 

Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technology and Director 
Certain commercial entities, equipment, or materials may be identified in this 

 document in order to describe an experimental procedure or concept adequately. 

Such identification is not intended to imply recommendation or endorsement by the 

National Institute of Standards and Technology, nor is it intended to imply that the 

entities, materials, or equipment are necessarily the best available for the purpose. 

National Institute of Standards and Technology Technical Note 1760 

Natl. Inst. Stand. Technol. Tech. Note 1760, 64 pages (December 2013)

CODEN: NTNOEF 
ABSTRACT 

A standard procedure is needed for obtaining smoke toxic potency data for use in fire hazard and 

risk analyses. Room fire testing of finished products is impractical, directing attention to the use 

of apparatus that can obtain the needed data quickly and at affordable cost. This report examines 

the first of a series bench-scale fire tests to produce data on the yields of toxic products in both 

pre-flashover and post-flashover flaming fires. The apparatus is the radiant furnace in NFPA 

269 and ASTM E 1678. Test specimens were cut from finished products that were also burned 

in room-scale tests: a sofa made of upholstered cushions on a steel frame, particleboard 

bookcases with a laminated finish, and household electric power cable. Initially, the standard 

test procedure was followed, with a variation to reduce the contribution to the effluent of postflaming pyrolysis. Subsequent variations in the procedure included cutting the test specimen into 

small pieces and performing the tests at a reduced oxygen volume fraction of 0.17. The yields of 

CO2 CO, HCl, and HCN were determined. The yields of other toxicants (NO, NO2, 

formaldehyde, and acrolein) were below the detection limits, but volume fractions at the 

detection limits were shown to be of limited toxicological importance relative to the detected 

toxicants. In general, dicing the test specimen and performing the tests at the reduced oxygen 

volume fraction had little effect on the toxic gas yields, within the experimental uncertainties. 

The exceptions were an increase in the CO yield for diced specimens at reduced oxygen, a 

decrease in the HCN yield from the intact sofa and cable specimens at reduced oxygen, and an 

increase in the HCN yield from dicing the cable specimens. In none of the procedure variations 

did the CO yield approach the value of 0.2 found in real-scale postflashover fire tests. 

Keywords: fire, fire research, smoke, room fire tests, fire toxicity, smoke toxicity 

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TABLE OF CONTENTS
 

LIST OF FIGURES ....................................................................................................................................................... VI
 

LIST OF TABLES......................................................................................................................................................... VI
 

I. INTRODUCTION......................................................................................................................................... 1
 

A. CONTEXT OF THE RESEARCH ........................................................................................................................................1
 

B. OBTAINING INPUT DATA.............................................................................................................................................2
 

C. PRIOR ROOM‐SCALE TESTS..........................................................................................................................................3
 

1. Test Configuration ......................................................................................................................................3
 

2. Combustibles ..............................................................................................................................................4
 

3. Test Conduct...............................................................................................................................................8
 

D. PHYSICAL FIRE MODELS .............................................................................................................................................9
 

II. EXPERIMENTAL INFORMATION ................................................................................................................11
 

A. SUMMARY OF NFPA 269/ASTM E 1678 APPARATUS.............................................................................................11
 

1. Hardware..................................................................................................................................................11
 

2. Gas Sampling and Analysis Systems.........................................................................................................15
 

B. OPERATING PROCEDURES ....................................................................................................................................19
 

1. "Standard" Testing ...................................................................................................................................19
 

2. Test Specimens .........................................................................................................................................20
 

3. Test Procedure Variation ..........................................................................................................................21
 

C. DATA COLLECTION..............................................................................................................................................22
 

III. CALCULATION METHODS..........................................................................................................................23
 

A. NOMENCLATURE ................................................................................................................................................23
 

B. MASS LOSS RATE................................................................................................................................................24
 

C. NOTIONAL GAS YIELDS ........................................................................................................................................24
 

D. CALCULATED GAS YIELDS .....................................................................................................................................25
 

1. CO and CO2 ...............................................................................................................................................25
 

2. HCl ............................................................................................................................................................27
 

3. HCN...........................................................................................................................................................27
 

4. Other Gases..............................................................................................................................................28
 

IV. RESULTS...................................................................................................................................................29
 

A. TESTS PERFORMED .............................................................................................................................................29
 

B. CALCULATIONS OF TOXIC GAS YIELDS WITH UNCERTAINTIES .......................................................................................36
 

V. DISCUSSION.............................................................................................................................................39
 

A. OVERALL TEST VALUES ........................................................................................................................................39
 

B. SPECIMEN PERFORMANCE AND TEST REPEATABILITY .................................................................................................39
 

1. CO2 and CO ...............................................................................................................................................39
 

2. HCl and HCN .............................................................................................................................................45
 

C. MEASURED VS. NOTIONAL VALUES ........................................................................................................................46
 

D. SPECIES SAMPLING AND MEASUREMENT.................................................................................................................46
 

1. Species Measurement Using FTIR Spectroscopy.......................................................................................46
 

2. Chimney Sampling ....................................................................................................................................47
 

E. IMPORTANCE OF UNDETECTED GASES ....................................................................................................................48
 

VI. CONCLUSION ...........................................................................................................................................51
 

VII. ACKNOWLEDGMENTS .................................................................................................................................53
 

REFERENCES............................................................................................................................................................55
 

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LIST OF FIGURES 

FIGURE 1. PHOTOGRAPH OF THE RADIANT TEST APPARATUS.....................................................................................................11
 

FIGURE 2. SCHEMATIC OF THE RADIANT TEST APPARATUS ........................................................................................................11
 

FIGURE 3. PHOTOGRAPH OF THE COMBUSTION CELL, SPECIMEN SUPPORT, RADIANT HEATERS, AND CHIMNEY...................................12
 

FIGURE 4. SCHEMATIC OF THE RADIANT FLUX DISTRIBUTION TEMPLATE......................................................................................13
 

FIGURE 5. MEAN RADIANT FLUX VS. RADIANT HEATER POWER SETTING. ERROR BARS ARE THE STANDARD DEVIATION ACROSS THE
 

DIFFERENT GAUGE POSITIONS.....................................................................................................................................14
 

FIGURE 6. FTIR SPECTRUM OF THE PRODUCTS OF BURNING ELECTRICAL CABLE............................................................................18
 

FIGURE 7. PHOTOGRAPHS OF TEST SPECIMENS.......................................................................................................................22
 

FIGURE 8. CO2 VOLUME FRACTION VS. PEAK AREA.................................................................................................................25
 

FIGURE 9. [CO/CO2]CHAMBER VS. [CO/CO2]CHIMNEY. .................................................................................................................26
 

FIGURE 10. RATIOS OF CO2 AND CO VOLUME FRACTIONS MEASURED USING NDIR AND FTIR SPECTROSCOPY VS. THE NDIR CO/CO2
 

VOLUME FRACTION RATIO. ........................................................................................................................................29
 

FIGURE 11. GAS VOLUME FRACTIONS FROM FOUR BOOKCASE SPECIMEN TESTS. (SOLID, CO2; DOTTED, CO; DASHED, O2). ..................40
 

FIGURE 12. COMPARISON OF OXYGEN CONSUMPTION (TOP HALF OF FIGURE) AND CO2 PRODUCTION (BOTTOM HALF OF FIGURE) IN
 

BOOKCASE SPECIMEN TESTS AT OXYGEN VOLUME FRACTIONS OF 0.21 (SOLID LINES) AND 0.17 (DOTTED LINES).........................41
 

FIGURE 13. COMPARISON OF CO PRODUCTION IN BOOKCASE SPECIMEN TESTS WITH OXYGEN VOLUME FRACTIONS OF 21 % (SOLID LINES)
 

AND 17 % (DOTTED LINES). NOTE THE CHANGE OF ORDINATE SCALE AT MASS LOSS OF 50 %.................................................42
 

FIGURE 14. COMPARISON OF CO PRODUCTION IN BOOKCASE SPECIMEN TESTS IN SLAB (SOLID LINES) AND DICED (DOTTED LINES)
 

CONFIGURATIONS. NOTE THE CHANGE OF ORDINATE SCALE AT MASS LOSS OF 50 PERCENT....................................................43
 

FIGURE 15. COMPARISON OF CO PRODUCTION IN ELECTRICAL CABLE TESTS IN WHOLE (SOLID LINES) AND DICED (DOTTED LINES)
 

CONFIGURATIONS. NOTE THE CHANGE OF ORDINATE SCALE AT MASS LOSS OF 50 PERCENT....................................................44
 

FIGURE 16. COMPARISON OF OXYGEN CONSUMPTION (TOP HALF OF FIGURE) AND CO2 PRODUCTION (BOTTOM HALF OF FIGURE) IN SOFA
 

SPECIMEN TESTS AT OXYGEN VOLUME FRACTIONS OF 0.21 (SOLID LINES) AND 0.17 (DOTTED LINES)........................................45
 

LIST OF TABLES 

TABLE 1. ELEMENTAL ANALYSIS OF FUELS................................................................................................................................5
 

TABLE 2. ELEMENTAL ANALYSIS OF FUEL COMPONENTS.............................................................................................................7
 

TABLE 3. HEATS OF COMBUSTION OF FUELS............................................................................................................................7
 

TABLE 4. TYPICAL MEASURED RADIANT FLUX VALUES.............................................................................................................13
 

TABLE 5. SPECIES AND FREQUENCY WINDOWS FOR FTIR ANALYSIS............................................................................................19
 

TABLE 6. CALCULATED NOTIONAL YIELDS OF TOXIC PRODUCTS FROM THE TEST SPECIMENS. ..........................................................24
 

TABLE 7. DATA FROM BOOKCASE MATERIAL TESTS. ................................................................................................................30
 

TABLE 8. GAS YIELDS FROM BOOKCASE MATERIAL TESTS. ........................................................................................................31
 

TABLE 9. DATA FROM SOFA MATERIAL TESTS. .......................................................................................................................32
 

TABLE 10. GAS YIELDS FROM SOFA MATERIAL TESTS. .............................................................................................................33
 

TABLE 11. DATA FROM CABLE MATERIAL TESTS. ....................................................................................................................34
 

TABLE 12. GAS YIELDS FROM CABLE MATERIAL TESTS. ............................................................................................................35
 

TABLE 13. YIELDS OF COMBUSTION PRODUCTS FROM RADIANT FURNACE TESTS..........................................................................36
 

TABLE 14. FRACTIONS OF NOTIONAL YIELDS OF COMBUSTION PRODUCTS FROM RADIANT FURNACE TESTS. ......................................37
 

TABLE 15. LIMITS OF IMPORTANCE OF UNDETECTED TOXICANTS................................................................................................49
 

. 

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I. INTRODUCTION 

A. Context of the Research 

Estimation of the times that building occupants will have to escape, find a place of refuge, or 

survive in place in the event of a fire is a principal component in the fire hazard or risk 

assessment of a facility. An accurate assessment enables public officials and facility owners to 

provide a selected or mandated degree of fire safety with confidence. Without this confidence, 

regulators and/or designers tend to apply large safety factors to lengthen the tenable time. This 

can increase the cost in the form of additional fire protection measures and can eliminate the 

consideration of otherwise desirable facility designs and construction products. Error in the 

other direction is also risky, in that if the time estimates are incorrectly long, the consequences of 

a fire could be unexpectedly high. 

Such fire safety assessments now rely on some form of computation that takes into account 

multiple, diverse factors, including the facility design, the capabilities of the occupants, the 

potential growth rate of a design fire, the spread rates of the heat and smoke, and the impact of 

the fire effluent (toxic gases, aerosols, and heat) on people who are in or moving through the fire 

vicinity.1

 The toolkit for these assessments, while still evolving, has achieved some degree of 

maturity and quality. The kit includes such tools as: 

 Computer models of the movement and distribution of fire effluent throughout a facility. 

o	 Zone models, such as CFAST2, have been in use for over two decades. This 

model takes little computational time, a benefit achieved by simplifying the air 

space in each room into two zones. A number of laboratory programs, validation 

studies3, and reconstructions of actual fires have given credence to the 

predictions.4 

o	 Computational fluid dynamics (CFD) models, such as the Fire Dynamics 

Simulator (FDS)5

, have seen increased use over the past decade. FDS is more 

computationally intense than CFAST in order to provide three-dimensional 

temperature and species concentration profiles. There has been extensive 

verification and validation of FDS simulations.5, 6 

These models calculate the local temperatures and combustion product concentrations as 

the fire develops. These profiles can be used for estimating when a person would die or 

be incapacitated, i.e., is no longer able to effect his/her own escape. 

 Devices such as the cone calorimeter7

 and larger scale apparatus8, which are routinely 

used to generate information on the rat of heat release as a commercial product burns. 

 A number of standards from ISO TC92 SC3 that provide support for the generation and 

use of fire effluent information in fire hazard and risk analyses.9 Of particular 

importance is ISO 13571, which provides consensus equations for estimating the human 

incapacitating exposures to the narcotic gases, irritant gases, heat, and smoke generated 

in fires.10 

More problematic are the sources of data for the production of the harmful products of 

combustion. Different materials can generate fire effluent with a wide range of toxic potencies. 

1 
 

Most furnishing and interior finish products are composed of multiple materials assembled in a 

variety of geometries, and there is as of yet no methodology for predicting the evolved products 

from these complex assemblies. Furthermore, the generation of carbon monoxide (CO), the most 

common toxicant, can vary by orders of magnitudes, depending on the fire conditions.11 

An analysis of the U.S. fire fatality data12 showed that post-flashover fires comprise the leading 

scenarios for life loss from smoke inhalation. Thus, it is most important to obtain data regarding 

the generation of harmful species under post-flashover (or otherwise underventilated) 

combustion conditions. Data for pre-flashover (well-ventilated) conditions have value for 

ascertaining the importance of prolonged exposure to "ordinary" fire effluent and to short 

exposures to effluent of high potency. 

B. Obtaining Input Data 

The universal metric for the generation of a toxic species from a burning specimen is the yield of 

that gas, defined as the mass of the species generated divided by the consumed mass of the 

specimen.13 If both the mass of the test specimen and the masses of the evolved species are 

measured continuously during a test, then it is possible to obtain the yields of the evolved species 

as the burning process, and any chemical change within the specimen, proceeds. If continuous 

measurements are not possible, there is still value in obtaining a yield for each species integrated 

over the burning history of the test specimen. 

The concentrations of the gases (resulting from the yields and the prevalent dilution air) are 

combined using the equations in ISO 13571 for a base set of the most prevalent toxic species. 

Additional species may be needed to account for the toxic potency of the fire-generated 

environment. 

To obtain an indicator of whether the base list of toxic species needs to be enhanced, living 

organisms should also be exposed to the fire effluent. The effluent exposure that generates an 

effect on the organisms is compared to the effect of exposure to mixtures of the principal toxic 

gases. Disagreement between the effluent exposure and the mixed gas exposure is an indicator 

of effluent components not included in the mixed gas data or the existence of synergisms or 

antagonisms among the effluent components. This procedure has been standardized, based on 

data developed using laboratory rats.14,15 However, it is recognized that animal testing is not 

always possible. In these cases, it is important to identify, from the material degradation 

chemistry, a reasonable list of the degradation and combustion products that might be harmful to 

people. 

Typically, the overall effluent from a fire is determined by the large combustibles, such as a bed 

or a row of auditorium seats. The ideal fire test specimen for obtaining the yields of effluent 

components is the complete combustible item, with the test being conducted in an enclosure of 

appropriate size. Unfortunately, reliance on real-scale testing of commercial products is 

impractical, both for its expense per test and for the vast number of commercial products used in 

buildings. Such testing is practical for forensic investigations in which there is knowledge of the 

specific items that combusted. 

2 
A more feasible approach for obtaining toxic gas yields for facility design involves the use of a 

physical fire model – a small-scale combustor that captures the essence of the combustible and of 

the burning environment of interest. The test specimen is an appropriate cutting from the full 

combustible. To have confidence in the accuracy of the effluent yields from this physical fire 

model, it must be demonstrated: 

	 How to obtain, from the full combustible, a representative cutting that can be 

accommodated and burned in the physical fire model; 

	 That the combustion conditions in the combustor (with the test specimen in place) are 

related to the combustion conditions in the fire of interest, generally pre-flashover 

flaming (well ventilated or underventilated), post-flashover flaming, pyrolysis, or 

smoldering; 

	 How well, for a diverse set of combustible items, the yields from the small-scale 

combustor relate to the yields from real-scale burning of the full combustible items; and 

	 How sensitive the effluent yields are to the combustor conditions and to the manner in 

which the test specimen was obtained from the actual combustible item. 

At some point, there will be sufficient data to imbue confidence that testing of further 

combustibles in a particular physical fire model will generate yields of effluent components with 

a consistent degree of accuracy. 

The National Institute of Standards and Technology (NIST) has completed a project to establish 

a technically sound protocol for assessing the accuracy of bench-scale device(s) for use in 

generating fire effluent yield data for fire hazard and risk evaluation. In this protocol, the yields 

of harmful effluent components are determined for the real-scale burning of complete finished 

products during both pre-flashover and post-flashover conditions. Specimens cut from these 

products are then burned in various types of bench-scale combustors using their standard test 

protocols. The test protocols are then varied within the range of the combustion conditions 

related to these fire stages to determine the sensitivity of the test results to the test conditions and 

to provide a basis for improving the degree of agreement with the yields from the room-scale 

tests. 

This report continues with a brief description of the previously conducted room fire tests. The 

full details can be found in Reference 16. Following this recap are the details of the tests using 

the first of four bench-scale apparatus to be examined. 

C. Prior Room-scale Tests 

1. Test Configuration 

With additional support from the Fire Protection Research Foundation, NIST staff conducted a 

series of room-fire tests of three complex products [16]. The burn room was 2.44 m wide, 2.44 

m high, and 3.66 m long (8 ft x 8 ft x 12 ft). The attached corridor was a 9.75 m (32 ft) long 

3 
extension of the burn room. A doorway 0.76 m (30 in.) wide and 2.0 m (80 in.) high was 

centered in the common wall. The downstream end of the corridor was fully open. 

2. Combustibles 

Three fuels were selected for diversity of physical form, combustion behavior, and the nature and 

yields of toxicants produced. Supplies of each of the test fuels were stored for future use in 

bench-scale test method assessment. 

	 “Sofas” made of up to 14 upholstered cushions supported by a steel frame. The cushions 

consisted of a zippered cotton-polyester fabric over a block of a flexible polyurethane 

(FPU) foam. The fire retardant in the cushion padding contains chlorine atoms. Thus, 

this fuel would be a source of CO2, CO, HCN, HCl, and partially combusted organics. 

The ignition source was the California TB133 propane ignition burner17 faced downward, 

centered over the center of the row of seat cushions. In all but two of the tests, the sofa 

was centered along the rear wall of the burn room facing the doorway. In the other two 

tests, the sofa was placed in the middle of the room facing away from the doorway to 

compare the burning behavior under different air flow conditions. Two of the first group 

of sofa tests were conducted in a closed room to examine the effect of vitiation on fire 

effluent generation. In these, an electric “match” was used to initiate the fires. 

	 Particleboard (ground wood with a urea formaldehyde binder) bookcases with a 

laminated polyvinylchloride (PVC) finish. This fuel would be a source of CO2, CO, 

partially combusted organics, HCN, and HCl. To sustain burning, two bookcases were 

placed in a “V” formation, with the TB133 burner faced upward under the lower shelves. 

	 Household wiring cable, consisting of two 14 gauge copper conductors insulated with a 

nylon and a polyvinyl chloride (PVC), an uninsulated ground conductor, two paper filler 

strips, and an outer cable jacket of a plasticized PVC. This fuel would be a source of 

CO2, CO, HCl, and partially combusted organics. Two cable racks containing 3 trays 

each supported approximately 30 kg of cable in each of the bottom two trays and 

approximately 17 kg in each of the middle and top trays. The cable trays were placed 

parallel to the rear wall of the burn room. Twin propane ignition burners were centered 

under the bottom tray of each rack. 

The elemental chemistry of each combustible was determined by an independent testing 

laboratory. The analytical chemical data are shown in Table 1. The elemental composition of 

the component materials in the fuels is shown in Table 2. Additional data on the heats of 

combustion (triplicate samples) are shown in Table 3. 

The details of the composition of the fuels and their test configurations are discussed below. The 

ignition modes and test configurations were selected to provide burning durations (under both 

well-ventilated and ventilation-limited conditions) that were long enough for accurate 

combustion product analyses. In some cases, adherence to realism was sacrificed to achieve this. 

Some of the sofas were burned in two different orientations to estimate the effect of fuel location 

on combustion product yields. 

4 
Table 1. Elemental Analysis of Fuels. 

Mass % 

Sample C H N Cl Ca Pb Al Sb P Sn Ti Total Δ * 

Particle Board, with laminate 46.89 6.70 2.68 0.26 n n n n n n n 56.53 43.4

46.56 6.68 3.35 0.24 n n n n n n n 56.83 43.1

47.12 6.60 2.76 0.26 n n n n n n n 56.74 43.2

 Mean value 46.86 6.66 2.93 0.25 56.70 43.3

 Standard deviation 0.28 0.05 0.37 0.01 0.15 0.1Pressboard, with laminate 43.04 6.12 0.21 0.14 n n n n n n n 49.51 50.4

43.12 6.08 0.21 0.15 n n n n n n n 49.56 50.4

42.73 6.20 0.18 0.14 n n n n n n n 49.25 50.7

 Mean value 42.96 6.13 0.20 0.14 49.44 50.5

 Standard deviation 0.21 0.06 0.02 0.01 0.17 0.1Cushion fabric 47.23 6.23 0.18 n n n n n n n n 53.64 46.3

48.12 6.10 0.19 n n n n n n n n 54.41 45.5

47.38 5.99 0.20 n n n n n n n n 53.57 46.4

 Mean value 47.58 6.11 0.19 53.87 46.1

 Standard deviation 0.48 0.12 0.01 0.47 0.4

Cushion padding 56.38 8.48 12.58 0.95 n n n n 0.20 n n 78.59 21.4

56.33 8.58 12.50 0.90 n n n n 0.15 n n 78.46 21.5

56.36 8.53 12.46 0.71 n n n n 0.21 n n 78.27 21.7

 Mean value 56.36 8.53 12.51 0.85 0.19 78.44 21.5

 Standard deviation 0.03 0.05 0.06 0.13 0.03 0.16 0.1

Cable jacket 40.83 5.07 <0.10 26.77 10.42 < 0.05 72.67 27.3

40.94 5.20 <0.10 26.53 10.18 < 0.05 72.67 27.3

40.87 5.15 <0.10 26.68 10.24 < 0.05 72.70 27.3

 Mean value 40.88 5.14 26.66 10.28 < 0.05 72.68 27.3
Mass % 

Sample C H N Cl Ca Pb Al Sb P Sn Ti Total Δ * 

 Standard deviation 0.06 0.07 0.12 0.10 0.02 0.0Wire insulation 48.25 6.73 2.39 26.04 0.80 0.62 83.41 16.5

48.20 6.98 2.65 26.08 0.81 0.62 83.91 16.048.57 6.82 2.40 26.22 0.72 0.63 84.01 15.9

 Mean value 48.34 6.84 2.48 26.11 0.78 0.62 83.78 16.2

 Standard deviation 0.20 0.13 0.15 0.09 0.04 0.00 0.32 0.3Cable filler 42.58 6.65 <0.10 n 49.23 50.7

42.42 6.84 <0.10 n 49.26 50.7

42.72 6.80 <0.10 n 49.52 50.4

 Mean value 42.57 6.76 49.34 50.6 Standard deviation 0.15 0.10 0.16 0.1Cable residue 18.39 2.30 0.20 22.99 43.88 56.1

25.42 

19.03 2.45 0.21 27.76 49.45 50.5

28.62 

17.91 2.47 0.14 30.00 50.52 49.4

27.87

 Mean value 18.44 2.41 0.18 26.96 47.95 52.0

 Standard deviation 0.56 0.09 0.04 2.51 3.57 3.5

* [1 - Σ (mass %) of listed elements] ** See following text for estimation methods 
Table 2. Elemental Analysis of Fuel Components. 

Mass % 

Sample C H N Cl Ca Pb Al Sb P Sn Ti Ash 

Wood 49.0 6.1 0.2 0.5 Paper 49.0 6.1 0.2 0.5 

Urea formaldehyde 33.3 5.6 38.9 PVC 38.4 4.8 56.7 Dioctyl phthalate 73.8 9.8 Melamine 28.6 4.8 66.7 

Cotton ( = cellulose) 44.5 6.2 

Polyethylene terephthalate 62.5 4.2 

Nylon 6,6 64 9.3 12 

Nylon 6 66 10.2 11 

FPU foam 57.6 5.6 11.2 

Table 3. Heats of Combustion of Fuels. 

Sample 

Δ

Hc (MJ/kg) Mean 

σ

Particle Board, with laminate 18.24 18.17 18.07 18.16 0.07 

Pressboard, with laminate 16.48 16.18 16.26 16.31 0.03 

Cushion fabric 18.17 17.96 17.94 18.02 0.10 

Cushion padding 26.09 26.02 26.12 26.08 0.04 PVC sheet 16.67 16.48 1.27 16.47 0.17 Cable jacket 18.30 18.41 18.36 18.36 0.04 

Wire insulation 23.39 23.33 23.45 23.39 0.06 Cable filler 17.01 17.00 17.00 17.00 0.00 Cable residue Did not ignite 
 

The mass fractions of cover fabric and padding in the sofa cushions were determined to be 

0.205 ± 0.004 and 0.795 ± 0.004, respectively. Since the cushions appeared to burn evenly (i.e., 

the fabric was generally not burned away well before the foam was) and since they were virtually 

consumed in the tests, we presumed that the elemental composition of the fuel was steady during 

the tests. We then estimated the cushion composition (mass fraction) to be: 

C: 0.545  1 % 

H: 0.080  1 % 

N: 0.100  1 % 

Cl: 0.0068  16 % 

P: 0.0015  17 % 

O: 0.267  4 % 

The derived value for the heat of combustion for the cushions is 24.4 MJ/kg  3 %. The mass 

density of the foam was measured as 0.031 g/cm3  6 %; the areal density of the cover fabric was 

measured as 0.019 g/cm2  4 %. 

For the bookcases, we estimated the fuel composition (mass fraction) to be: 

C: 0.481  0.6 % 

H: 0.062  0.8 % 

N: 0.029  13 % 

Cl: 0.0030  4 % 

O: 0.426  1 % 

The heat of combustion for the bookcase is 18.2 MJ/kg  0.4 %. 

For the electric power cable, we measured the mass fractions of the insulation, filler paper, and 

jacket to be 0.516  0.007, 0.033  0.0007, and 0.239  0.007, respectively. The remainder of 

the mass was the copper wire. For the combustible material, the elemental composition was: 

C: 0.576  0.5 % 

H: 0.080  1.5 % 

Cl: 0.323  0.4 % 

N: 0.021  6 % 

The heat of combustion for the combustible fraction of the cable is 21.60 MJ/kg  0.6 %. 

3. Test Conduct 

During each test, the mass of each test specimen was monitored continuously. The 

concentrations of CO2, CO and O2 were monitored in the burn room and at three locations in the 

corridor using species-specific analyzers. Fourier transform infrared (FTIR) spectroscopy was 

used to monitor CO2, CO, HCN, HCl, HF, HBr, NO, NO2, H2CO (formaldehyde), and C3H4O 

8 
 

 

(CH2=CH-CH=O, acrolein) near the upstream and downstream ends of the corridor. Soot was 

measured gravimetrically near these two locations. All measurements were intended to be in the 

upper smoke layer. In the two tests with the doorway blocked, the effluent was sampled from 

the upper layer of the burn room. 

For the open-door tests, the yields of the gases were determined by defining the pre- and postflashover time intervals, determining the test specimen mass loss and the average volume 

fractions of the gases during those intervals, calculating the pre- and post-flashover yields of CO2 

from the above plus the calculated total mass flow through the doorway, and determining the 

yields of the other gases using the ratios of their mass fractions to the mass fraction of CO2. 

For the closed-room tests, we assumed that the upper layer was well mixed. The measured 

volume fractions of the gases and the ideal gas law were used to calculate the mass of each 

species in the upper layer. These were normalized to specimen mass loss as a function of time. 

The uncertainty in the yield values resulted from the sensitivity of the yield to the selected time 

pre- or post-flashover time interval, the uncertainty in the specimen mass loss, the uncertainty in 

the species mass flow out the doorway (for open door tests), and the quality of the assumptions 

inherent in the calculation of the mass of product in the upper layer (for closed room tests). For 

the closed room tests, the uncertainty was further estimated by comparing the yield values from 

the early combustion with those from the pre-flashover segments of the open door sofa tests. 

The analysis of similar tests also structured the determination of uncertainty and repeatability. 

Many HCl and HCN measurements were close to the instrumental background. Nonetheless, the 

data were sufficient to obtain reasonable post-flashover yield values and pre-flashover yield 

estimates for the three combustibles. The post-flashover HCl and HCN concentrations were also 

high enough to obtain estimates of the degree of loss of the compounds down the length of the 

corridor. The pre-flashover values had too high a degree of uncertainty for this use. 

The equations in ISO 13571 allow for additional gases to be included in estimating the time 

available for escape or refuge from a fire. The composition of the combustibles precluded the 

formation of some of these. Three key sensory irritants (NO2, acrolein, and formaldehyde) were 

not detected, thus establishing the upper limits of their presence. Analysis of these levels in light 

of their incapacitation concentrations from ISO 13571 showed they would have had less than a 

20 % contribution to incapacitation relative to the concentration of HCl, except in the case of the 

bookcases, which produced little HCl. This unimportance of secondary toxicants is consistent 

with the results of the animal experiments used to establish the N-gas hypothesis that attributes 

fire effluent lethality to a small number of gases.18 

D. Physical Fire Models 

Historically, there have been numerous bench-scale devices that were intended for measuring the 

components of the combustion effluent.19,20 The combustion conditions and test specimen 

configuration in the devices vary widely, and some devices have flexibility in setting those 

conditions. Currently, ISO TC92 SC3 (Fire Threat to People and the Environment) is proceeding 

toward standardization of one of these devices, a tube furnace (ISO/TS 1970021) and is 

9 
 

considering standardization of another, the cone calorimeter (ISO 5660-122) with a controlled 

combustion environment. There are concurrent efforts in Europe and ISO to upgrade the 

chemical analytical capability for a closed box test (ISO 5659-223). Thus, before too long there 

may well be diverse (and perhaps conflicting) data on fire effluent component yields available 

for any given product. This situation does not support either assured fire safety or marketplace 

stability. 

Only one device, used in both NFPA 26914 and ASTM E167815, has been validated with animal 

exposure and gas measurement data against real-scale fire test data for the same materials, and 

then only for post-flashover yields of the principal toxicants.24 The three, relatively 

homogeneous materials were Douglas fir, a rigid polyurethane foam, and an unplasticized PVC. 

The toxicology of the combustion products varied significantly among the three materials. 

Laboratory rats were exposed to the combustion effluent for 30 min and then observed for 

14 days. The times of any animal deaths were recorded. The yields of the principal toxicants 

were also determined. 

The validation was conducted according to five hypotheses: 

1.	 The equal LC50 hypothesis: LC50 valuesi

, as measured in the bench-scale test and in the 

real scale, agree to within the acceptable uncertainty. 

2.	 The primary toxic gas hypothesis: The bench-scale test shows the same primary toxic 

gases as the real-scale test. 

3.	 The equal yields hypothesis: The yields of the measured toxic gases are the same, to 

within the acceptable uncertainty, in the bench-scale and in the real-scale tests. 

4.	 The N-Gas hypothesis: The real-scale and the bench-scale results agree, to with the 

acceptable uncertainty, with predictions based on measured gas concentration and 

computations made according to the N-Gas Model.ii 

5.	 The type-of-death hypothesis: The type of death (within- or post-exposure) is similar for 

the bench-scale and for the real-scale tests. 

The agreement between the bench-scale results and the real-scale results was deemed to be 

within a factor of three, based on the hypothesis with the worst agreement. The LC50 values 

agreed within approximately ± 50 %. 

The existence of this prior validation suggested that this apparatus was a reasonable starting 

point for the current project. Accordingly, the apparatus was evaluated for specimens of the 

same batches of the finished product used in the previously reported room-fire tests.16 These 

combustibles were non-homogeneous and more complex than the three, relatively homogeneous 

materials previously used to estimate the validity of NFPA 269 and ASTM E 1678. 

i

 The LC50 is the concentration of a species that leads to the death of half (50 %) of the test animals within a 

specified time interval. An analogous metric is the IC50 where the observed response is incapacitation. 

ii When polymeric materials are thermally decomposed and burned, there are hundreds of species in the effluent. 

The N-Gas model postulates that the toxic potency of the effluent can be substantially explained using a small 

number, N, of these species. Typically, N is fewer than 10. 

10 
 

II. EXPERIMENTAL INFORMATION 

A. Summary of NFPA 269/ASTM E 1678 Apparatus 

1. Hardware 

The apparatus consists of a radiant combustion cell, a collection chamber for the combustion 

effluent, and a chimney connecting the two. Figure 1 is a photograph of the apparatus, Figure 3 

is a schematic of the apparatus, and Figure 3 depicts the combustion cell and radiant heaters; 

more detailed diagrams are in the NFPA and ASTM Standards. A brief description of the three 

components follows. 

Figure 1. Photograph of the Radiant Test Apparatus. 

Heating Elements Heating Elements 

A B C D E F Exposure Chamber 

(6 exposure ports) 

Chimney 

Combustion Custion Chamber 

(with sample holder) 

Figure 2. Schematic of the Radiant Test Apparatus 

11 
Figure 3. Photograph of the Combustion Cell, Specimen Support, Radiant 

Heaters, and Chimney. 

a. Combustion Cell 

The combustion cell is fabricated from a quartz ground glass joint, approximately 0.3 m long and 

0.13 m in inner diameter. Within the cell is a platform upon which sits a tray containing the test 

specimen. A load cell sits below the combustion cell and is connected to the specimen tray by a 

solid rod. The load cell has a capacity of 500 g, with a rated resolution of 0.1 g. Electrodes are 

located within the cell to enable spark ignition of the specimen pyrolyzate. 

Two quartz heaters, whose axes are parallel to the length of the combustion cell, apply radiant 

energy to the test specimen. According to the standard test procedures in the Standards, the 

orientation of the radiant heat lamps is to be adjusted so that no measurement at seven locations 

across the face of the specimen deviates more than 10 % from the average. Figure 4 depicts the 

steel template used to determine the radiant flux distribution. The template is made of steel sheet 

stock, with dimensions 8 cm x 13 cm x 5 cm high. The eight holes are approximately 1.4 cm in 

diameter. 

12 
 

 

 

2 8

1 

3 

5 

4 

6 

7 

Figure 4. Schematic of the Radiant Flux Distribution 

Template. 

The following procedure was used to determine the magnitude and uniformity of the radiant flux 

imposed on the test specimen for a given electrical power supplied to the heaters. The template 

was placed on the specimen platform and a Schmidt-Boelter heat flux gauge was inserted into 

the template such that its top surface was flush with the top surface of the template. A power 

setting for the radiant heaters was selected, and the heaters were allowed to stabilize for 

approximately five minutes. The electrical output of the gauge was recorded and converted to a 

radiant flux using the calibration curve supplied by the manufacturer. The gauge was then 

moved to each of the other holes in the template and the heat flux valued recorded. The 

orientations of the heaters were then adjusted such that all measurements were within 10 % of 

the mean value, as required in the standards. One set of values is shown in Table 4. All are 

within the required interval except for the low value at Position 1 for the power setting of 250, 

and the high Position 2 value (at 350), both of which deviate by approximately 2 kW/m2 . These 

are insignificant in the overall radiant flux to the test specimen, approximately no more than a 

5 % flux reduction over approximately one-eighth of the surface. Figure 5 is a plot of these 

mean radiant flux values as a function of the dial setting on the heater power source. 

Table 4. Typical Measured Radiant Flux Values. 

Input 

Power 

Setting 

Radiant Flux (kW/m2

) 

Gauge Position 

1 2 3 4 5 6 7 8 Mean 

100 13 13 15 13 14 14 12 13 13.4 

250 35 44 45 37 43 44 38 40 40.8 

350 58 70 62 56 68 64 57 60 61.8 

13 
     

0

10

20

30

40

50

60

70

0 100 200 300 400

Mean Radiant Flux (kW/m2)

Radiant Heater Power Setting

Figure 5. Mean Radiant Flux vs. Radiant Heater Power Setting. Error bars are the 

standard deviation across the different gauge positions. 

All of the tests reported here were conducted at an irradiance of nominally 50 kW/m2 . Over 

time, the heaters aged and the radiant flux for a given power setting changed. The output of the 

heaters was checked periodically, and the appropriate power setting was selected. 

b. Collection Chamber 

The effluent collection chamber was fabricated of clear polycarbonate with inside dimensions of 

1.22 m wide x 0.45 m deep x 0.37 m high, for a nominal volume of 0.2 m3 . Across the front of 

the chamber are six ports, each nominally 63 mm inner diameter and 100 mm in length. They 

will be referred to as Ports A through F, from left to right in the figures above. In the standards, 

these are intended for supporting housings for the rats that would be exposed to the combustion 

effluent. In the tests reported here, the ports were closed with rubber stoppers. Four of the 

stoppers were penetrated by 6.25 mm outer diameter copper tubing. These were gas sampling 

and return lines for the fixed gas (CO, CO2, and O2) analyzers and a Fourier transform infrared 

(FTIR) analyzer. Toward the left end of the chamber floor is a rectangular hole to the chimney, 

through which gas flowed to and from the combustion cell. A hinged lid to cap the chimney is 

operable from outside the chamber. On the right side of the floor of the chamber is a small fan to 

minimize any stratification of the combustion effluent within the chamber. Also on the right side 

of the chamber is a port for a plastic expansion bag. As warm combustion effluent enters the 

14 
chamber, the gas temperature in the chamber rises and the expansion bag inflates, minimizing 

any pressure increase in the chamber. This temperature rise did not exceed approximately 10 %. 

c. Chimney 

The 0.3 m tall chimney consists of three rectangular channels. The center channel (nominally 

150 mm x 30 mm internal dimension) is centered over the test specimen. During a test, the 

combustion effluent rises through this center channel into the collection chamber. Flanking the 

center channel are two channels, each of whose internal cross section is nominally 70 mm x 

30 mm. During a test, gas from the collection chamber flows downward through these channels 

to the burning specimen. The chimney is sealed to the combustion cell and to the collection 

chamber to minimize gas leakage during a test. 

2. Gas Sampling and Analysis Systems 

In the room-scale tests (Section I.C), measurements were made of 12 gases. Water and methane 

were included because of their potential interference with the quantification of the toxic gases. 

Two of the toxic gases, HBr and HF, were not found in the combustion products because there 

was no fluorine or bromine in the test specimens. The remaining eight toxic gases were acrolein 

(C3H4O), Carbon monoxide (CO), carbon dioxide (CO2), formaldehyde (CH2O), hydrogen 

chloride (HCl), hydrogen cyanide (HCN), nitric oxide (NO), and nitrogen dioxide (NO2). Some 

of these turned out to be generated at levels that would not have contributed significantly to the 

incapacitation of exposed people. Thus, it was deemed unlikely that animal tests would have 

added much tenability information. As a result, the same gases were monitored in the benchscale tests, and no animals were exposed. The basis for comparison between tests of the same 

combustibles at the two scales is the yields of the chemically diverse set of toxicants. 

CO and CO2 were quantified using a nondispersive infrared (NDIR) gas analyzer; oxygen was 

quantified by a paramagnetic analyzer in the same instrument. The precisions of the analyzers, 

as provided by the manufacturer, were: 

CO: 10 μL/L 

CO2: 0.02 L/L 

O2: 0.05 L/L 

For sampling from the collection chamber, gas was continuously drawn from Port C of the 

collection chamber through copper tubing of 6.35 mm outer diameter. The flow passed through 

a coiled tube immersed in a water ice bath; an impinger bottle immersed in dry ice, with its upper 

half filled with glass wool; and finally a glass fiber disk filter before reaching the pump and 

being returned to the chamber through Port F. The traps and filter removed particulates and 

condensable species, including water, that would otherwise interfere with and possibly harm the 

analyzer. The return minimized the effect of gas removal on the contents of the chamber. While 

sampling, the flow was maintained at 1 L/min for the CO and CO2 detectors and 0.2 L/min for 

the O2 detector. The analyzer itself was calibrated daily with zero and span gases (a mixture of 

5000 μL/L CO and 0.08 L/L of CO2 in nitrogen, and ambient air (0.2095 L/L oxygen on a dry 

basis)). The span gas is certified to be accurate to within 2 % of the value. 

15 
 

 

The concentrations of CO, CO2, and the additional six toxic gases were measured using a Midac 

Fourier transform infrared (FTIR) spectrometeriii equipped with a stainless steel flow cell (2 mm 

thick KBr windows and a 11.5 cm optical pathlength), maintained at (170 ±5) °C. Samples were 

drawn through a heated 6.35 mm (1⁄4 in.) copper tube from a fitting mounted in Port E with its tip 

at approximately the same location as the sampling line for the NDIR analyses. The sample was 

pulled through the sampling line and flow cell by a small pump located downstream from the 

flow cell, and then returned to the collection chamber through Port A. There were no traps or 

filters in this sampling line. The pump flow was measured at 10 L/min maximum, but was at 

times lower due to fouling of the sampling lines with smoke deposits. 

In general, lower limits of FTIR detection for the gases were desired. For example, the 

30-minute LC50 value (150 μL/L in the N-gas model14) for HCN is only a few times the 

minimum detection limit in this instrument. Improved signal to noise ratios were achieved by 

sampling through the side of the center channel of the chimney, approximately 7 cm below the 

top. At this location, the effluent volume fractions were significantly higher than they were in 

the collection chamber since the flow had not yet been diluted into 200 L of air. Presumably the 

effluent undergoes no further chemistry once past the chimney sampling location and into the 

cool, well-mixed gas in the collection chamber. Thus, ideally, the ratio of the volume fraction of 

a trace gas in the chimney to the volume fraction of a more easily quantifiable gas, such as CO2, 

in the chimney should be the same as the ratio of the volume fractions of the gases in the 

collection chamber. However, because the test apparatus is designed to recirculate gas from the 

collection chamber to the combustion chamber, an unknown fraction of the gas passing the 

chimney sampling port is from the collection chamber rather than the sample, having already 

been “counted” on a previous trip up the chimney. So instead, we used the average volume 

fractions in the chimney over the course of the sample burn, and then related this to the final 

volume fraction in the collection chamber. The signal to noise ratio was also improved by 

averaging up to several hundred spectra prior to quantification. 

In a typical run, gas was sampled (for FTIR analysis) from the chimney from the start of the test 

until flaming ceased. The sampling was then switched to the Port E sampling location by 

rotating a T-valve fitting that was connected, via more heated copper tube, to the flow cell. 

It was not possible to observe the flame height in the chimney, and for a number of the tests, the 

flame extended out of the chimney and a few centimeters into the collection chamber. This 

meant that the combustion products could be undergoing reaction downstream of the sampling 

port, and that the volume fractions extracted from the chimney were not necessarily the final 

values. The magnitude of the error introduced by this phenomenon was estimated as follows. 

	 In all the tests, CO2 was the dominant carbon-containing gas; the volume fraction of CO 

was no more than 10 % of the volume fraction of CO2. Thus, oxidation of some part of 

the CO (or other organic species) downstream of the chimney sampling port would not 

appreciably affect the volume fraction of CO2. 

iii Certain commercial equipment, products, or materials are identified in this document in order to describe a 

procedure or concept adequately or to trace the history of the procedures and practices used. Such identification is 

not intended to imply recommendation, endorsement, or implication that the products, materials or equipment are 

necessarily the best available for the purpose. 

16 
	 The volume fractions of CO and CO2 in the collection chamber, which were measured 

after the specimen flaming had ceased, were indicative of the full flame chemistry. The 

same is true of the ratio of these two volume fractions. 

	 Comparing the ratio of the two volume fractions in the chimney to the ratio in the 

collection chamber provided an indication of the degree of CO oxidation in the extended 

flame. 

A similar process might have been followed for HCN and the other organic combustion 

products. However, their volume fractions in the collection chamber were too small to be 

quantified. The procedure for estimating these yields or upper limits of these yields is described 

in Sections III.F.3 and III.F.4. 

HCl is generated soon after the specimen pyrolysis and is not oxidized downstream. Thus, the 

ratio of the volume fractions of HCl to CO2 measured in the chimney should be nominally the 

same as the ratio in the collection chamber. 

An example of a spectrum measured by FTIR spectroscopy during one such test is displayed in 

Figure 6. The series of peaks extending from about 3050 cm-1 to 2600 cm-1 are due to HCl. In 

this case, it is possible to resolve the individual frequencies corresponding to changes in the 

population of rotational states as the H-Cl bonds vibrate. This is usually only possible for small 

gas phase molecules. There are three spectral features due to CO2 that are evident in this 

spectrum. The most intense, centered at 2350 cm-1, corresponds to asymmetric stretching of the 

two C=O bonds. The symmetric stretch is not observed because there is no change in dipole 

moment when both O atoms move in phase. The second feature, seen as two distinct peaks 

centered at about 3650 cm-1, is an overtone band that derives from the simultaneous excitation of 

these bond-stretching modes. The third peak at about 650 cm-1 is due to the out of plane bending 

of the molecule. There are bands due to the C≡O stretching vibrations in carbon monoxide, 

centered at about 2150 cm-1. The remaining peaks in this spectrum are due to H2O. 

Using these spectra, gas concentrations were quantified using the Autoquant software. This is a 

software package for performing real time and off-line quantitative analyses of target 

compounds, and is based on the Classical Least Squares (CLS) algorithm as described by 

Haaland et al.25 In this method, the measured spectra are fit to linear combinations of reference 

spectra corresponding to the target compounds. 

Calibration spectra were obtained from a quantitative spectral library assembled by Midac26 and 

from a collection of spectra provided the Federal Aviation Administration who performed benchscale fire tests on similar materials.27 In this analysis, the least squares fits were restricted to 

characteristic frequency regions or windows for each compound that were selected in such a way 

as to maximize the discrimination of the compounds of interest from other components present in 

fire gases. All reference spectra were recorded at 170 °C and ambient pressure. 

The identities of the target compounds (as well as other compounds that absorb at the same 

frequencies and must, therefore, be included in the analyses), their corresponding concentrations 

(expressed in units of μL/L for a mixture of the calibration gas and N2 in a 1 meter cell), and the 

characteristic spectral windows used in the quantitative analyses are listed in Table 5. 

17 
Also listed in this Table are minimum detection limits (MDLs) for each of the target compounds. 

These values, which represent the lowest concentrations that can be measured with the 

instrumentation employed in these tests, were estimated as follows. The calibration spectra were 

added to test spectra (which, when possible, were selected in such a way that only the compound 

of interest was not present) with varying coefficients until the characteristic peaks of the target 

compounds were just discernible above the baseline noise. The value of signal averaging over 

ca. 100 spectra was included. The MDL values reported in Table 5 were obtained by 

multiplying these coefficients by the known concentrations of the target compound in the 

calibration mixtures. 

Water, methane and acetylene are included in the quantitative analyses because they have 

spectral features that interfere with the target compounds. The nitrogen oxides absorb in the 

middle of the water band that extends from about 1200 cm-1 to 2050 cm-1. Consequently, the 

limits of detection for these two compounds are higher than for any of the other target 

compounds. Thus, it is not surprising that their presence was not detected in any of the tests. 

4500 4000 3500 3000 2500 2000 1500 1000 500

Wavenumber (cm‐1)

H2O H2O

CO

CO2

CO2

HCl

CO2

Figure 6. FTIR Spectrum of the Products of Burning Electrical Cable. 

18 
Table 5. Species and Frequency Windows for FTIR Analysis. 

Compound 

Reference 

Volume Fraction 

(μL/L) 

Frequency 

Window (cm-1) 

Minimum 

Detection Limit 

(μL/L) 

CH4 483 2800 to 3215 20 

C3H4O 2250 850 to 1200 20 

CH2O 11300 2725 to 3000 40 

CO2 47,850 660 to 725, 2230 to 2300 800a 

CO 2410 2050 to 2225 20 

H2O 100,000 1225 to 2050, 3400 to 4000 130a 

HCl 9870 2600 to 3100 20 

HCN 507 710 to 722, 3200 to 3310 35 

NO 512 1870 to 1950 70 

NO2 70 1550 to 1620 40 a Present in the background. 

Delay times for gas flows from the sampling locations within the test structure to the gas 

analyzers were small compared to the duration of the specimen burning. The burn durations 

were at least 2 min for the bookcase specimens, at least 2 min for the cable specimens, and at 

least 1 min for the sofa specimens. Combining the gas sample pumping rate and the volumes of 

the sampling lines, the delay time to the oxygen analyzer was about 5 s, about 1 s to the CO and 

CO2 analyzers, and 0.1 s to the FTIR analyzer. Since the yield calculations involved averaged 

volume fractions over the duration of the burning, delay time effects were neglected. 

B. Operating Procedures 

1. "Standard" Testing 

The intent was to test specimens of each of the three finished products in the manner prescribed 

in the two Standards, although without the use of test animals. The steps in the procedure are: 

	 Calibrate the heat flux to the specimen surface and calibrate the gas analyzers (each 

performed daily). 

	 Weigh the specimen holder without and with the test specimen. 

	 Open the shutter. 

	 Insert the test specimen on the specimen holder and cap the combustion cell. 

	 Turn on the gas sampling system and establish background data for the combustion 

product concentrations and baseline data for the initial specimen mass. 

	 Turn on the quartz heaters and turn on the spark igniter. 

19 
 

 Record the time of ignition and turn off the spark igniter. 

 Record the time of flameout. 

 Fifteen minutes after turning on the igniter and heaters, turn off the power to the heaters. 

 Collect concentration data for a total of 30 min. 

 Dispose of any residue of the test specimen and prepare for the next test. 

As prescribed in the two Standards, the specimen mass is to be such that the estimated value of 

the Fractional Effective Dose (FED) for a 30 min exposure of rats to the effluent is near 

unity.14,15 Preliminary tests were performed to approximate this specimen mass. 

During preliminary tests, it was observed that the specimens of the bookcase material continued 

to smolder after the flames disappeared, and specimens of the power cable continued to pyrolyze. 

Since the purpose of the small-scale tests was to obtain data for pre- and post-flashover flaming 

combustion, inclusion of the smoldering/pyrolysis effluent in the collection chamber 

environment would be misleading. (In the room tests, there was no sustained external heating of 

the burning finished goods.) Thus, upon observation of flameout, the shutter was immediately 

closed and the power to the heaters turned off. At the same time, to minimize the risk of a flame 

puff upon opening the combustion chamber, the chamber was flushed with nitrogen to quench all 

reaction. 

2. Test Specimens 

Consistent with the standard procedure, we maintained a specimen configuration that 

approximated the full combustible item. The initial sofa specimens were a single piece of foam, 

7.5 cm by 7.5 cm by 1 cm thick, covered with a single piece of the polyester/cotton cover fabric, 

7.5 cm x 7.5 cm, on the upper (exposed) surface. The initial bookcase specimens were single, 7.5 

cm x 10 cm pieces of the particle board, with the vinyl surface facing the radiant heaters. The 

initial cable specimens were three 7.5 cm lengths of cable cut from the spool. Sample sizes were 

chosen to produce a Fractional Effective Dose (FED) near 1, as determined by the N-gas model 

for lethality to rats.14,15 

m  CO 21%  O 2  HCN  HCl  HBr FED     

 CO  b 21 LC50O2 LC50 HCN LC50 HCl LC50 HBr 2 

m  CO 21%  2  HCN  HCl  HBr  

O 

  

 CO  b 21%  5.4 % 150 μL L 3700 μL/L 3000 μL L 2 

φx is the volume percent of CO2 or O2 (100  L/L) and the volume fraction in μL/L for the other 

gases above. m and b are empirically determined constants such that if φCO2 < 5 % then m = -18 

and b = 122,000; whereas if φCO2 > 5 % then m = 23 and b = -38,600. Little effort was made to 

fine-tune the FED, since animals were not being exposed to the effluent. 

20 
3. Test Procedure Variation 

One of the purposes of this program was to obtain effluent composition data in tests with variants 

on the standard operating procedure. This would enable estimation of the sensitivity of the gas 

yields to the manner in which the test specimen was derived from the complete combustible 

object and examination of the potential for an improved relationship with the yield data from the 

room-scale tests. For this apparatus, two such variations were examined: 

	 Variation of the combustion environment to more closely approach the post-flashover 

conditions that occurred in the room-scale tests. This entailed changing the initial oxygen 

volume fraction. During pre-flashover burning, the air entrained by a fire has an oxygen 

volume fraction of nominally 0.21. This fraction is lower for post-flashover fires. 

Preliminary experiments indicated that flaming combustion of specimens from all three 

finished products could be initiated for an initial oxygen volume fraction in the collection 

chamber as low as 0.17. This atmosphere was created by flowing nitrogen into the 

collection chamber prior to the start of a test until the oxygen analyzer indicated a steady 

oxygen volume fraction of 0.17. 

	 Test specimen conformation. To determine the importance of specimen inhomogeneity 

(e.g., due to layering of the component materials), the test specimens from the sofas and 

bookcases were cut into pieces with dimensions on the order of 1 cm and randomly 

arranged in the sample holder. The cable specimens were cut into lengths less than 1 cm 

and the insulating materials separated. For these diced specimens, (a) materials from the 

interior of the finished product were directly exposed to the radiant flux and ambient 

atmosphere and (b) the surface area available for combustion or pyrolysis was increased. 

In each case the quantity of material was the same mass as that used in the intact 

specimen (generally approximately 90 g, 6 g, and 30 g for the particleboard, foam, and 

cable, respectively.) Figure 7 presents photographs of the intact and diced test 

specimens. 

21 
Intact Bookcase Diced Bookcase 

Intact Cable Diced Cable 

Intact Sofa Diced Sofa 

Figure 7. Photographs of Test Specimens. 

C. Data Collection 

The signals from the load cell and the fixed gas analyzer were collected using a personal 

computer with National Instruments data acquisition hardware and software. Values were 

recorded at 1 s intervals. The FTIR spectra were recorded using the FTIR computer system. 

Spectra were taken every 1 s to 6 s. 

During each test, four times were recorded manually. These were the start of test, first observed 

flaming, cessation of visible flaming, and conclusion of the test. Additional notes were recorded, 

such as failure of an instrument, clogging of a sampling line, and flames extending above the top 

of the chimney. 

22 
 

 

III. CALCULATION METHODS 

A. Nomenclature 

The following nomenclature is used in this section: 

F carbon mass fraction in the fuel (dimensionless) 

∆m mass loss of the test specimen (g) 

M molecular weight (kg kmol-1) 

p pressure (Pa) 

T temperature (K) 

y species yield (dimensionless) 

α combustion expansion factor (dimensionless) 

 combustion efficiency (dimensionless) 

 volume fraction of gas g (dimensionless) = pg / pT 

 global equivalence ratio (dimensionless) 

ρ gas density (kg m-3) 

V volume of the collection chamber (L) 

Superscripts 

A refers to concentrations in the analyzer 

C refers to concentrations near the top of the chimney 

EC refers to concentrations in the collection chamber 

Subscripts 

amb ambient air 

dry dry air 

f fire 

g a gas, g 

x refers to a specific gas of interest, e.g., CO, CO2 

not refers to the notional yield of a combustion product 

t total 

23 
B. Mass Loss Rate 

The specimen mass loss during a test was determined from the initial and final readings from the 

load cell. The uncertainty in the mass loss was derived from the uncertainties in these two 

measurements. The noise in these measurements was reduced by using the average of 10 points. 

Care was taken to allow the specimen holder to cool before the final measurements to cool so 

that thermal buoyancy would not affect the measured value of the specimen residue. No 

consideration was given to whether the chemical composition of the residue (if any) was 

different from the composition of the specimen at the beginning of the test. Mass loss 

percentages were calculated from the load cell data using the previously identified initial and 

final readings, and the instantaneous reading to calculate mass lost up to that point. 

C. Notional Gas Yields 

The notional, or maximum possible, gas yields (Table 6) were calculated as follows: 

 CO2: Assume all the carbon in the test specimen is converted to CO2. Multiply the 

mass fraction of C in the test specimen (Table 2 or Section II.C) by the ratio of the 

molecular mass of CO2 to the atomic mass of carbon. 

 CO: Assume all the carbon in the test specimen is converted to CO. Multiply the mass 

fraction of C by the ratio of the molecular mass of CO to the atomic mass of carbon. 

 HCN: Assume all the nitrogen in the test specimen is converted to HCN. Multiply the 

mass fraction of N by the ratio of the molecular mass of HCN to the atomic mass of 

nitrogen. 

 HCl: Assume all the chlorine in the test specimen is converted to HCl. Multiply the 

mass fraction of Cl by the ratio of the molecular mass of HCl to the atomic mass of 

chlorine. 

The notional yields from the bookcase and cable specimens were assumed to be the same as the 

yields from the intact combustibles.16 The sofa specimen had a mass ratio of fabric to foam that 

differed modestly from the intact sofas. 

Table 6. Calculated Notional Yields of Toxic Products from the Test Specimens. 

Gas 

Notional Yields 

Bookcase Cable 

Sofa 

1 layer foam 

1 layer fabric 

CO2 1.72 ± 1 % 2.11 ± 1 % 1.95 ± 4 % 

CO 1.09 ± 1 % 1.33 ± 1 % 1.24 ± 4 % 

HCN 0.057 ± 13 % 0.040 ± 6 % 0.193 ± 4 % 

HCl 0.0026 ± 4 % 0.332 ± 1 % 0.0069 ± 19 % 

The uncertainty in the notional yield values is determined by the uncertainty in the prevalence of 

the central element (in the bullets just above) in the combustible. These uncertainties were 

estimated in Section I.C. For the cuttings from the sofas, the uncertainty in the notional yields 

24 
 

was increased by the small variability (estimated at 3 percent) in the relative masses of the fabric 

and padding materials in the test specimens. 

D. Calculated Gas Yields 

1. CO and CO2 

Yields of CO and CO2 were calculated using the volume of the collection chamber, the gas 

concentrations in the chamber (accounting for the background concentrations in room air), the 

consumed mass of the fuel, and the ideal gas law. 

pg V = mg R T/Mg 

yg = [g pt V Mg] / [R T ∆mfuel] 

where R is the universal gas constant, 8.31 x 103

 L-Pa/mol-K. The pressure, temperature, gas 

volume fractions, and mass lost from the test specimen were all measured in the laboratory. 

We soon discovered that the CO2 absorption band used by the FTIR spectrometer software was 

saturated, so that the FTIR peak intensity was not proportional to the volume fraction. 

Accordingly, we calculated the area under the CO2 absorption band for a number of volume 

fractions and plotted the results against the FTIR spectrometer software values for known 

CO2/air mixtures. This is shown in Figure 8. This enabled determining the relationships of 

volume fractions of other gases measured in the chimney to their volume fractions in the 

collection chamber. The concentrations of the other gases were sufficiently low that their 

absorption bands were not saturated. 

Figure 8. CO2 Volume Fraction vs. Peak Area. 

25 
 

 

A plot of the values of [CO/CO2]chamber vs. [CO/CO2]chimney did not show the expected linear 

relationship with an intercept at the origin (Figure 9). Figure 9 suggests that when the combustion 

at the sampling point is relatively efficient (between < 1 percent CO by volume and 4 percent 

CO by volume), partial oxidation of pyrolyzate leads to a relatively constant CO concentration 

emanating from the reaction volume. As the combustion becomes less complete, pyrolyzate 

oxidation and CO burnout in the plume proceed at comparable rates. At any rate, the CO volume 

fractions in the chamber were always large enough that the measurements there could be used to 

calculate the CO yields. 

Figure 9. [CO/CO2]chamber vs. [CO/CO2]chimney. 

Another consideration for the yield calculations was the value of the chamber volume. During 

the course of a test, the expansion bag inflated both due to the temperature rise in the collection 

chamber and to the additional gaseous combustion products from the burning test specimen. 

	 The initial temperature in the chamber was typically 296 K and the typical temperature 

rises were to approximately 330 K or lower. Thus, the peak volume expansion from this 

source was about 10 %. After the burning had ceased, the gas in the chamber cooled due 

to contact with the chamber walls, and the temperature returned essentially to room 

temperature. Thus, by using the final volume fractions of the two gases in calculating the 

gas yields, it was consistent to use the chamber volume with the bag deflated. 

	 The specimen combustion ceased when the fuel was consumed or when the oxygen 

volume fraction in the chamber neared 0.14. For this amount of oxygen consumption, 

26 
calculations for complete combustion of either a hydrocarbon fuel (i.e., containing no 

oxygen) or a wood-like fuel indicate that the generated combustion gases would expand 

the volume by about 3 % or 7 %, respectively. This contribution to the bag expansion 

would not change as the chamber gases cooled. However, some of the combustion 

products (e.g., much of the water vapor) would condense as the temperature dropped or 

would be adsorbed on the chamber surfaces. Thus, at the end of the test, the increase in 

the gas volume would be of the order of 5 % or less and was neglected. 

For each experiment, the uncertainty in the yield values for these two gases resulted from: 

	 The uncertainty in the volume fraction measurement in the chimney. This was typically 

less than 5 percent. 

	 The uncertainty in the specimen mass loss. This was typically less than 1 percent. 

	 The uncertainty in the collection chamber volume. This was on the order of 1 percent. 

We therefore assigned a numerical uncertainty of ± 5 percent to the yields of CO and CO2. 

There was also a contribution to the repeatability of the test results from variation in the 

combustion of each test specimen. As will be seen below, this was generally larger than the 

above uncertainties. 

2. HCl 

The only calculable HCl yields were from the cable specimens. Above the chimney sampling 

point, HCl should not have been generated or consumed by any flames extending through the 

chimney. The yields were calculated by multiplying the yield of CO2 by the ratio of the volume 

fraction of HCl in the chimney to the volume fraction of CO2 in the chimney and the ratio of 

molecular weights of the two gases. The estimated uncertainty in the HCl volume fractions was 

± 10 percent, and the estimated uncertainty in the HCl yields was ± 15 percent. 

3. HCN 

There were some calculable HCN yields from the sofa and cable specimens. The HCN volume 

fractions in the chamber were close to the limit of detection; thus, it was preferred to calculate 

HCN yields using the volume fractions in the chimney. However, as with CO, there is the 

potential for HCN to be oxidized to nitrogen oxides downstream of the chimney sampling 

location. To the extent that this occurs, the HCN volume fraction emerging from the flame 

would be overestimated. 

An estimate of the degree of HCN oxidation was obtained as follows. For those tests in which 

there were measurable volume fractions of HCN in both the chamber and the chimney, the ratio 

of the volume fractions of CO2 in the two locations was 2.9 ± 0.2. The ratio for the HCN volume 

fractions was 5.5 ± 1.8. The greater variability in the latter ratio was likely due to the closeness 

of some of the chamber volume fractions to the limit of detection and to differences in the flame 

extension beyond the sampling point. Of more importance is the fact that the HCN ratio is 

approximately double the CO2 ratio, indicating that typically about half of the HCN had been 

oxidized before entering the chamber. 

27 
As a result, the yields of HCN were estimated by multiplying the yield of CO2 by the ratio of the 

volume fraction of HCN in the chimney to the volume fraction of CO2 in the chimney, then by 

the ratio of molecular weights. The results were then divided by two as an estimate of the 

oxidized fraction: 

yHCN = 1⁄2 yCO2 (HCN, chimney/ CO2, chimney)(MHCN/M CO2) 

The estimated uncertainty in the larger values of the HCN volume fraction was ± 25 percent, and 

the estimated uncertainty in the HCN yields was ± 30 percent. The uncertainty increased as 

values of HCN approached the limit of detection. 

4. Other Gases 

The volume fractions of the other toxic gases in both the chimney and the collection chamber 

were always below the detection limit. Thus, the upper limits of the yields of these gases were 

estimated using their limits of detection. 

28 
IV. RESULTS 

A. Tests Performed 

The following is the test numbering key, with format F-Y-m-[O2]-N, where 

F: Fuel [S = sofas; B = bookcases; P = power cable] 

Y: 1 = intact specimen; 2 = diced specimen 

m: Approximate initial specimen mass (g). For the sofa specimens, this is followed by 

the number of layers of fabric and of foam.

 [O2] Approximate initial oxygen volume percent in the collection chamber 

N: Replicate test number for that set of combustible and conditions 

Some of the replicate runs are not included if an instrument failed or if one of the sampling lines 

became clogged. 

Table 7 through Table 12 present the test data and the calculated yields for the bookcase, sofa, 

and cable specimens, respectively. In these tables, Δt is the observed duration of flaming 

combustion and Δm is the measured mass lost during the flaming combustion. The horizontal 

colored bands highlight groups of replicate tests. A yield number in red indicates a higher 

uncertainty due to the volume fraction being near the limit of detection. 

All yields were calculated from NDIR volume fractions (CO, CO2) or referenced to the NDIR 

values for CO2 (HCN, HCl). The mean ratio of NDIR volume fraction values to FTIR volume 

fraction values for CO2 was 0.86 ± 0.24; the ratio for CO was a nearly identical 0.85 ± 0.24. 

Figure 10 shows there was not a strong dependence of this ratio on the type of specimen or the 

completeness of combustion. 

Figure 10. Ratios of CO2 and CO volume fractions measured using NDIR and FTIR 

spectroscopy vs. the NDIR CO/CO2 volume fraction ratio. 

29 
Table 7. Data from Bookcase Material Tests. 

Code Size 

Specimen 

Mass (g) 

Δm 

(g) 

Δt (s) 

Flaming 

NDIR Chamber Final 

O2 

(L/L) 

FTIR (Chamber) FTIR (

CO2 

(L/L) 

CO 

(L/L) 

CO2 

(L/L) 

CO 

(L/L) 

HCl 

(L/L) 

CO2 

(L/L) 

CO 

(L/L) 

B-1-90-21-2 slab 76 x95x20 90.9 29.6 313 0.0706 2530 0.135 0.0706 3670 110 0.0805 1360 B-1-90-21-3 slab 76 x95x20 88.1 26.9 195 0.0618 3200 0.145 0.0560 2020 100 0.1046 910 

B-1-90-21-4 slab 76 x95x20 87.8 25.6 270 0.0608 1270 0.145 0.0621 1250 0 0.0630 1200 B-1-90-21-5 slab 76 x95x20 89.4 25.3 235 0.0628 1160 0.143 0.0526 1160 30 0.0678 980 

B-1-90-21-6 slab 76 x95x20 89.6 29.5 293 0.0700 2680 0.136 0.0483 2060 20 0.0699 1680 

B-2-90-21-1 diced cubes 90.3 24.9 150 0.0629 2100 0.143 0.0558 1450 50 0.1027 1700 B-2-90-21-4 diced cubes 88.7 23.7 140 0.0567 1660 0.148 0.0615 1130 20 0.0764 380 

B-2-90-21-5 diced cubes 90.0 25.6 161 0.0632 1710 0.142 0.0570 1650 40 0.0946 1630 

B-1-90-17-1 slab 76 x95x20 89.8 14.4 110 0.0332 1010 0.137 0.0286 770 0 0.0628 1020 

B-1-90-17-2 slab 76 x95x20 92.1 18.2 148 0.0410 1360 0.131 0.0378 920 0 0.0662 970 

B-2-90-17-1 diced cubes 90.4 16.6 98 0.0348 1420 0.136 0.0311 980 0 0.0734 1500 B-2-90-17-2 diced cubes 90.4 18.9 148 0.0383 1920 0.133 0.0343 1330 40 0.0720 1420 
Table 8. Gas Yields from Bookcase Material Tests. 

Code Size 

Specimen 

Mass (g) 

Δm 

(g) 

yCO2 

(g/g) 

yCO 

(g/g) 

yHCN 

(g/g) 

yHCl 

(g/g) 

yNO 

(g/g) 

yNO2 

(g/g) 

Yacrol

(g/g

B-1-90-21-2 slab 76 x95x20 90.9 29.6 0.88 0.0200 < 0.00012 0.00097 < 0.0005 < 0.0005 < 0.0B-1-90-21-3 slab 76 x95x20 88.1 26.7 0.85 0.0279 < 0.00009 0.00020 < 0.0004 < 0.0003 < 0.0B-1-90-21-4 slab 76 x95x20 87.8 25.5 0.88 0.0115 < 0.00015 < 0.00000 < 0.0007 < 0.0006 < 0.0

B-1-90-21-5 slab 76 x95x20 89.4 26.0 0.92 0.0106 < 0.00015 < 0.00011 < 0.0006 < 0.0006 < 0.0

B-1-90-21-6 slab 76 x95x20 89.6 30.5 0.88 0.0213 < 0.00013 0.00030 < 0.0006 < 0.0005 < 0.0B-2-90-21-1 diced pieces 90.3 35.9 0.93 0.0197 < 0.00010 0.00081 < 0.0004 < 0.0004 < 0.0B-2-90-21-4 diced pieces 88.7 24.8 0.88 0.0163 < 0.00012 0.00065 < 0.0005 < 0.0005 < 0.0B-2-90-21-5 diced pieces 90.0 27.1 0.91 0.0156 < 0.00010 0.00031 < 0.0005 < 0.0004 < 0.0B-1-90-17-1 slab 76 x95x20 89.8 15.4 0.85 0.0162 < 0.00015 < 0.00022 < 0.0006 < 0.0006 < 0.0

B-1-90-17-2 slab 76 x95x20 92.1 18.7 0.83 0.0174 < 0.00013 < 0.00020 < 0.0006 < 0.0005 < 0.0

B-2-90-17-1 diced pieces 90.4 17.8 0.77 0.0199 < 0.00011 < 0.00017 < 0.0005 < 0.0004 < 0.0

B-2-90-17-2 diced pieces 90.4 19.6 0.75 0.0237 < 0.00011 0.00075 < 0.0005 < 0.0004 < 0.0
Table 9. Data from Sofa Material Tests. 

Code Size 

Specimen 

Mass (g) 

Δm 

(g) 

Δt (s) 

Flaming 

NDIR Chamber Final 

O2 

(L/L) 

FTIR (Chamber) FT

CO2 

(L/L) 

CO 

(L/L) 

CO2 

(L/L) 

CO 

(L/L) 

HCl 

(L/L) 

HCN 

(L/L) 

CO2 

(L/L) 



(L

5-1-6,1&1,21-1 76x64x25 6.1 5.4 123 0.0264 890 0.176 0.0129 520 0 30 0.0243 S-1-6,1&1-21-2 76x64x25 6.1 5.4 79 0.0239 610 0.180 0.0206 520 0 90 0.0580 1

S-1-6,1&1-21-3 76x64x25 6.2 5.4 73 0.0238 470 0.180 0.0151 490 0 0 corrupt corr

S-2-6,1&1-21-1 diced pieces 6.3 5.3 67 0.0244 720 0.180 0.0212 590 20 60 0.0541 1

S-2-6,1&1-21-2 diced pieces 6.3 5.5 64 0.0245 880 0.179 0.0216 710 30 120 0.0592 2

S-1-6,1&1-17-1 76x64x25 6.3 5.5 77 0.0244 860 0.144 0.0154 400 0 30 0.0404 1

S-1-6,1&1-17-2 76x64x25 6.2 5.6 70 0.0238 900 0.143 0.0212 730 0 10 0.0520 1

S-1-6,1&1-17-3 76x64x25 6.5 5.8 90 0.0250 810 0.142 0.0215 1410 10 50 0.0608 3

S-2-6,1&1-17-1 diced pieces 6.3 5.4 59 0.0246 840 0.143 0.0213 700 0 40 0.0589 1

S-2-6,1&1-17-2 diced pieces 6.3 5.2 55 0.0235 1380 0.147 0.0198 1020 0 90 0.0670 3

S-2-6,1&1-17-3 diced pieces 6.3 5.8 60 0.0249 1390 0.143 0.0216 1410 10 50 0.0603 3
Table 10. Gas Yields from Sofa Material Tests. 

Page Code Size 

Specimen 

Mass (g) 

Δm 

(g) 

yCO2 

(g/g) 

yCO 

(g/g) 

yHCN 

(g/g) 

yHCl 

(g/g) 

yNO 

(g/g) 

yNO2 

(g/g) 

109 5-1-6,1&1,21-1 76x64x25 6.1 5.4 1.80 0.038 < 0.00079 < 0.00119 < 0.0035 < 0.0031 

110 S-1-6,1&1-21-2 76x64x25 6.1 5.4 1.62 0.026 0.00327 0.00090 < 0.0013 < 0.0014 

136 S-1-6,1&1-21-3 76x64x25 6.2 5.4 1.62 0.020 

111 S-2-6,1&1-21-1 diced pieces 6.3 5.3 1.69 0.031 0.00297 0.00101 < 0.0015 < 0.0016 

112 S-2-6,1&1-21-2 diced pieces 6.3 5.5 1.63 0.037 0.00381 0.00111 < 0.0013 < 0.0014 

120 S-1-6,1&1-17-1 76x64x25 6.3 5.5 1.66 0.037 0.00076 < 0.00066 < 0.0020 < 0.0021 

121 S-1-6,1&1-17-2 76x64x25 6.2 5.6 1.68 0.040 0.00069 < 0.00052 < 0.0015 < 0.0016 

137 S-1-6,1&1-17-3 76x64x25 6.5 5.8 1.58 0.032 0.00152 < 0.00042 < 0.0012 < 0.0013 

122 S-2-6,1&1-17-1 diced pieces 6.3 5.4 1.64 0.035 0.00282 < 0.00045 < 0.0013 < 0.0014 

123 S-2-6,1&1-17-2 diced pieces 6.3 5.2 1.54 0.057 0.00515 < 0.00037 < 0.0011 < 0.0011 

138 S-2-6,1&1-17-3 diced pieces 6.3 5.8 1.58 0.056 0.00213 < 0.00042 < 0.0012 < 0.0013 
Table 11. Data from Cable Material Tests. 

Code Size 

Specimen 

Mass (g) 

Δm 

(g) 

NDIR Chamber 

Final 

O2 

(L/L) 

FTIR (Chamber) FTIR (

Δt (s) 

Flaming 

CO2 

(L/L) 

CO 

(L/L) 

CO2 

(L/L) 

CO 

(L/L) 

HCl 

(L/L) 

CO2 

(L/L) 

CO 

(L/L) 

C-1-30-21-3 3 x 127 mm 29.6 8.2 162 0.0242 2180 0.176 0.0209 1500 805 0.0322 1560 

C-1-30-21-4 3 x 127 mm 29.6 7.5 166 0.0262 2060 0.174 0.0222 1420 2479 0.0368 1850 

C-1-30-21-5 3 x 127 mm 29.6 8.2 186 0.0250 2110 0.174 0.0212 1990 23 0.0303 2650 C-1-30-21-6 3 x 127 mm 29.7 7.7 147 0.0245 2060 0.174 0.0201 1939 3420 0.0368 3240 C-1-30-21-7 3 x 127 mm 30.0 7.5 115 0.0232 2240 0.176 0.0188 2060 4710 0.0460 4320 C-2-30-21-2 diced pieces 29.7 8.1 135 0.0269 2300 0.173 0.0202 1820 2500 0.0329 2660 

C-2-30-21-3 diced pieces 29.3 7.7 157 0.0220 2680 0.179 0.0175 2390 4959 0.0128 1850 C-2-30-21-4 diced pieces 29.6 7.6 145 0.0191 1780 0.182 0.0211 2200 4000 0.0339 3190 

C-1-30-17-1 3 x 127 mm 29.7 8.1 186 0.0259 2790 0.138 0.0203 2360 3990 0.0286 3130 

C-1-30-17-2 3 x 127 mm 29.7 7.7 180 0.0245 2450 0.140 0.0197 2210 3900 0.0265 2720 C-2-30-17-1 diced pieces 29.4 7.3 127 0.0261 2590 0.136 0.0214 2300 4840 0.0312 3110 C-2-30-17-2 diced pieces 29.5 6.8 147 0.0259 1800 0.138 0.0214 1700 4530 0.0295 2210 
Table 12. Gas Yields from Cable Material Tests. 

Code Size 

Specimen 

Mass (g) 

Δm 

(g) 

yCO2 

(g/g) 

yCO 

(g/g) 

yHCN 

(g/g) 

yHCl 

(g/g) 

yNO 

(g/g) 

yNO2 

(g/g) 

Yac

(g

C-1-30-21-3 3 x 127 mm 29.6 8.2 1.08 0.057 0.00165 0.14 < 0.0016 < 0.0014 < C-1-30-21-4 3 x 127 mm 29.6 7.5 1.28 0.059 0.00128 0.19 < 0.0017 < 0.0014 < C-1-30-21-5 3 x 127 mm 29.6 8.2 1.28 0.059 0.00128 0.19 < 0.0017 < 0.0014 < C-1-30-21-6 3 x 127 mm 29.7 7.7 1.12 0.055 0.00045 0.22 < 0.0018 < 0.0015 < C-1-30-21-7 3 x 127 mm 30.0 7.5 1.17 0.057 0.00039 0.26 < 0.0015 < 0.0013 < C-2-30-21-2 diced pieces 29.7 8.1 1.13 0.064 0.00053 0.27 < 0.0012 < 0.0010 < C-2-30-21-3 diced pieces 29.3 7.7 1.22 0.061 < 0.00040 0.24 < 0.0018 < 0.0015 < 

C-2-30-21-4 diced pieces 29.6 7.6 1.05 0.076 < 0.00088 0.41 < 0.0039 < 0.0034 < 

C-1-30-17-1 3 x 127 mm 29.7 8.1 0.92 0.049 0.00042 0.20 < 0.0013 < 0.0011 < C-1-30-17-2 3 x 127 mm 29.7 7.7 1.17 0.075 0.00063 0.31 < 0.0020 < 0.0017 < C-2-30-17-1 diced pieces 29.4 7.3 1.17 0.069 < 0.00047 0.31 < 0.0021 < 0.0018 < 

C-2-30-17-2 diced pieces 29.5 6.8 1.31 0.077 < 0.00689 0.33 < 0.0020 < 0.0018 < 
 

 

 

 

 

 

B. Calculations of Toxic Gas Yields with Uncertainties 

Table 13 contains the yields of the combustion products calculated using the data from Table 8, 

Table 10, and Table 12. The estimated uncertainties reflect the repeatability of the volume 

fractions in replicate tests, uncertainties in the other terms in the yields calculations, and degree 

of proximity of the measured values to the background levels. 

Table 13. Yields of Combustion Products from Radiant Furnace Tests. 

GAS 

Initial 

O2 Form Bookcase Sofa Cable 

CO2 

0.21 Intact 0.88  8 % 1.68  10 % 1.16  11 % 

0.21 Diced 0.91  8 % 1.66  7 % 1.13  11 % 

0.17 Intact 0.84  8 % 1.64  8 % 1.05  17 % 

0.17 Diced 0.76  8 % 1.59  8 % 1.24  11 % 

CO 

0.21 Intact 0.0183  40 % 0.028  32 % 0.058  7 % 

0.21 Diced 0.0172  15 % 0.034  15 % 0.067  15 % 

0.17 Intact 0.0168  8 % 0.036  14 % 0.062  30 % 

0.17 Diced 0.0218  14 % 0.049  26 % 0.073  20 % 

HCN 

0.21 Intact < 2 x 10-4 < 3 x 10-3 9 x 10-3  65 % 

0.21 Diced < 1 x 10-4 3.4 x 10-3  45 % < 6 x 10-4 

0.17 Intact < 2 x 10-4 1.0 x 10-3  70 % 5 x 10-4  50 % 

0.17 Diced < 1 x 10-4 3.4 x 10-3  65 % < 7 x 10-3 

HCl 

0.21 Intact 3 x 10-4  x3 < 1 x 10-3 0.20  35 % 

0.21 Diced 6 x 10-4  45 % 1 x 10-3  25 % 0.31  40 % 

0.17 Intact < 2 x 10-4 < 7 x 10-4 0.25  40 % 

0.17 Diced < 8 x 10-4 < 5 x 10-4 0.32  18 % 

NO 

0.21 Intact < 7 x 10-4 < 3 x 10-3 < 2 x 10-3 

0.21 Diced < 5 x 10-4 < 2 x 10-3 < 2 x 10-3 

0.17 Intact < 6 x 10-4 < 2 x 10-3 < 2 x 10-3 

0.21 Diced < 5 x 10-4 < 1 x 10-3 < 2 x 10-3 

NO2 

0.21 Intact < 6 x 10-4 < 3 x 10-3 < 2 x 10-3 

0.21 Diced < 5 x 10-4 < 2 x 10-3 < 3 x 10-3 

0.17 Intact < 6 x 10-4 < 3 x 10-3 < 2 x 10-3 

0.21 Diced < 4 x 10-4 < 2 x 10-3 < 2 x 10-2 

Acrolein 

0.21 Intact < 4 x 10-4 < 2 x 10-3 < 1 x 10-3 

0.17 Diced < 3 x 10-4 < 6 x 10-4 < 1 x 10-3 

0.17 Intact < 4 x 10-4 < 8 x 10-4 < 1 x 10-3 

0.17 Diced < 3 x 10-4 < 6 x 10-4 < 1 x 10-3 

Formaldehyde 

0.21 Intact < 4 x 10-4 < 2 x 10-3 < 1 x 10-3 

0.21 Diced < 3 x 10-4 < 2 x 10-3 < 2 x 10-3 

0.17 Intact < 4 x 10-4 < 2 x 10-3 < 1 x 10-3 

0.17 Diced < 3 x 10-4 < 2 x 10-3 < 1 x 10-3 

36 
 

 

 

 

 

The values in Table 14 are the values from Table 13 divided by the notional yields from Table 6. 

Thus the uncertainties are the combined uncertainties from those two tables. 

Table 14. Fractions of Notional Yields of Combustion Products from Radiant 

Furnace Tests. 

GAS 

Initial 

O2 Form Bookcase Sofa Cable 

CO2 

0.21 Intact 0.51  9 % 0.86  14 % 0.55  12 % 

0.21 Diced 0.53  9 % 0.85  11 % 0.54  12 % 

0.17 Intact 0.47  9 % 0.84  12 % 0.50  18 % 

0.17 Diced 0.44  9 % 0.82  12 % 0.59  12 % 

CO 

0.21 Intact 0.0168  40 % 0.023  36 % 0.044  8 % 

0.21 Diced 0.0158  16 % 0.027  19 % 0.050  16 % 

0.17 Intact 0.0154  9 % 0.029  18 % 0.047  30 % 

0.17 Diced 0.0200  15 % 0.040  30 % 0.055  20 % 

HCN 

0.21 Intact < 4 x 10-3 < 2 x 10-2 0.22  70 % 

0.21 Diced < 2 x 10-3 1.8 x 10-2  50 % < 0.08 

0.17 Intact < 4 x 10-3 5 x 10-3  75 % 0.012  55 % 

0.17 Diced < 2 x 10-3 1.8 x 10-2  70 % < 0.2 

HCl 

0.21 Intact 0.1  x3 < 0.2 0.60  35 % 

0.21 Diced 0.2  50 % 0.15  45 % 0.94  40 % 

0.17 Intact < 8 x 10-2 < 0.1 0.75  40 % 

0.17 Diced < 3 x 10-2 < 0.07 0.96  20 % 

37 
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38 
 

V. DISCUSSION 

A. Overall Test Values 

The principal outcome of this series of tests is a well-documented set of combustion product 

yields. This includes the numerical values themselves, the apparatus conditions under which 

they were obtained, the uncertainty in their calculated values, and the repeatability of the tests. 

Next most important is a determination of the extent to which the toxic gas yields are affected by 

variations in the test protocol that are reasonable in light of possible variations in combustion 

conditions in fires involving the intact products. 

Third, it is important to evaluate the quality of the derived knowledge in the context of its 

intended use. The yield information would be used with a computational fire model (zone or 

CFD) to generate the time-dependent environment generated by a fire. Equations such as those 

in ISO 1357110 would then be used to assess whether the combination of occupancy design, 

contained combustibles, and occupant/responder characteristics lead to the desired level of life 

safety. 

The documentation of the yields has been provided in the earlier sections. The following 

examines the context and quality of the results. 

B. Specimen Performance and Test Repeatability 

1. CO2 and CO 

There was no significant effect on the CO2 and CO yields as a result of changing the initial 

oxygen volume fraction or dicing the test specimens. 

For the bookcase and sofa specimens, the repeatability of the CO2 yields was comparable to the 

uncertainties inherent in the volume fraction measurements. The scatter in the CO2 yields from 

the cable specimens was modestly higher, probably reflective of the variable HCl yields and the 

role of HCl as a flame inhibitor. 

The degree of repeatability in the CO yields was lower for all three types of specimens. The 

bookcase specimens were prone to unpredictable transition from flaming to smoldering, and 

some scoping tests had shown that the smoldering period generated a disproportionate yield of 

CO. There might have been some variability in the promptness in closing the shutter, isolating 

the combustion chamber from the collection chamber. This was not likely a major factor, since 

the uncertainties in the CO yields from the sofa and cable specimens were comparable to those 

for the bookcase specimens, and those two specimen types were less prone to smoldering. 

Another potential source of test-to-test variability was the promptness with which the test 

specimen was quenched with nitrogen following the closing of the shutter. This needs to be 

prescribed carefully in the test method, since the mass loss from the specimen could continue 

39 
after the shutter is closed and product gases were no longer being transferred to the collection 

chamber. However, this did not appear to be significant in this series of tests. 

Taking a closer look at the extent to which replicate tests burned in a consistent manner, Figure 

11 shows the resulting CO2 and CO volume fraction profiles from four similar bookcase tests. 

The progress of each test has been normalized by the extent of the burn, i.e., the total mass lost 

from the test specimen. The justification for normalizing by the extent of burn is to depict the 

repeatability of the test. If profiles generally match, this indicates that the specimens burned in a 

consistent manner. If, on the other hand, the profiles vary widely, as they do for CO in Figure 

11, this indicates a high variation from test to test. 

0.25 3000 

2500 

0.2 

Volume Fraction O 2 , CO2 (L/L) 

2000 

0.15 

1500 

0.1 

1000 

0.05 

500 

0 0 

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 

Mass Loss 

Volume Fraction CO ( L/L) 

Figure 11. Gas volume fractions from four bookcase specimen tests. (Solid, CO2; 

dotted, CO; dashed, O2). 

The depiction of volume fraction profiles shown in Figure 11 does not allow for easy comparison 

to other tests with different materials or conditions. Therefore subsequent figures show average 

profiles combining two or more tests of the same kind, using the following procedure. The data 

from a given test are rescaled so that the mass loss entries occur at regular intervals. Then, for a 

given mass loss percent, the volume fraction entries are averaged across multiple tests of the 

same type, and standard deviations taken. In the subsequent figures, the bold line represents the 

average of multiple tests and the lighter lines represent one standard deviation above and below 

that average. 

So, for example, Figure 12 combines the results of four tests with an initial oxygen volume 

fraction of 0.21 (solid lines) to results from two tests with an initial oxygen volume fraction of 

0.17 (dotted lines). Most significantly, although the oxygen volume fractions were different at 

40 
the start of the two sets of tests, by the end they were nearly the same. This implies that the 

particleboard burning is an oxygen-limited process and that once the oxygen volume fraction 

drops below 0.15, burning in the flaming mode ceases. If flaming is limited by a lack of 

oxygen, then the overall effect of reducing the initial oxygen volume fraction is to reduce the 

overall intensity of burning—a view supported by the reduction in CO2 production when the 

initial oxygen volume fraction was reduced, as seen in Figure 12. 

0 

0.05 

0.1 

0.15 

0.2 

0.25 

Volume Fraction O 2 (L/L) 

0 

0.02 

0.04 

0.06 

0.08 

0.1 

0.12 

0.14 

0.16 

0.18 

0.2 

Volume Fraction CO 2 (L/L) 

21 % O2 

17 % O2 

17 % O2 

21 % O2 

0% 20% 40% 60% 80% 100% 

Mass Loss 

Figure 12. Comparison of oxygen consumption (top half of figure) and CO2 

production (bottom half of figure) in bookcase specimen tests at oxygen volume 

fractions of 0.21 (solid lines) and 0.17 (dotted lines). 

The production of CO in the same sets of tests, shown in Figure 13, was also reduced when the 

initial oxygen volume fraction was reduced. In summary, lower initial oxygen gave less 

complete combustion, as expected. The difference was small, since the test specimens 

approached flame extinction as they approached the same residual oxygen volume fraction. 

In these tests, the FED values based on the volume fractions when progress reached a mass loss 

of 100 percent are 0.83 and 0.74 for oxygen volume fractions of 0.21 and 0.17, respectively. 

(These values are slightly higher than those computed for the 30 min exposure because over the 

course of those 30 minutes the falling temperature of the air allows the apparatus expansion bag 

to deflate, which introduces air that was sequestered from the recirculating and burning process.) 

The change in FED is primarily the result of a reduction in CO, although the contribution from 

oxygen depletion actually rises slightly. These values are well in the range specified by the 

standard (0.5 to 1.5); if they were not, it is uncertain whether the method of adjusting the sample 

size would be able to compensate. If the burning of the bookcase material in this apparatus is in 

fact oxygen-limited, then a larger sample would experience the same absolute mass loss as a 

41 
smaller sample, in both cases burning only until the oxygen volume fraction reaches 0.14 and 

producing identical quantities of CO and CO2 as were found here. 

0 

50 

100 

150 

200 

250 

300 

350 

Volume Fraction CO ( L/L) 

0 

500 

1000 

1500 

2000 

2500 

3000 

Volume Fraction CO ( L/L)

21 % O2 

17 % O2 

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 

Mass Loss 

Figure 13. Comparison of CO production in bookcase specimen tests with oxygen 

volume fractions of 21 % (solid lines) and 17 % (dotted lines). Note the change of

ordinate scale at mass loss of 50 %. 

Figure 14 compares the effect of dicing the bookcase specimen, depicting the CO production as a 

function of mass loss fraction. The primary observation from this comparison is that dicing the 

material serves to reduce the scatter of the results at all stages, as indicated by the much narrower 

standard deviation bands. And although it appears that at earlier stages of burning the CO 

production was lower in the diced configuration, it ultimately reached the same value in either 

case. An analysis of the production of CO2 and oxygen shows essentially the same trend ­

reduced scatter but ultimately reaching the same average value. 

42 
Volume Fraction CO ( L/L) 

350 

300 

250 

200 

150 

100 

50 

0 

3000 

2500 

2000 

1500 

1000 

500 

0 

Volume Fraction CO ( L/L) 

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 

Mass Loss 

Figure 14. Comparison of CO production in bookcase specimen tests in slab 

(solid lines) and diced (dotted lines) configurations. Note the change of ordinate 

scale at mass loss of 50 percent. 

Similar, but not identical behavior was found in the burning of diced and whole electrical cable 

specimens. As shown in Figure 15, the diced electrical cable specimens do appear to have 

produced less CO in the early stages of burning, but ultimately the exposure chamber CO volume 

fraction reached the same value as when the cables were whole. However, unlike with the 

bookcase specimen tests, dicing the electrical cables significantly expanded the standard 

deviation of the measured CO volume fractions in the later stages of burning. We hypothesize 

that this difference can be explained by the way dicing transformed the test specimen. In the 

case of the particleboard, the ignition of the whole slab depended on the behavior of the veneer, 

which peeled and blistered in an irregular way, changing the initial heat flux to the underlying 

wood. Dicing the particleboard significantly reduced the exposure of the veneer, so the primary 

exposure was to the homogenous wood particle matrix. The cable, on the other hand, is 

composed of multiple layers, including the PVC outer sheath, paper wrappers, individual 

conductor insulators, and the copper conductors. In the assembled product, these layers melted 

and burned in turn, presenting a spatially uniform material facing the radiant heaters. In the 

diced configuration, the cables consisted of a randomly-ordered array of 1 cm pieces of four or 

five different materials. This approach does not allow for strict control of the material 

distribution across the sample holder. Whereas dicing the bookcase material reduced its disorder 

to the scale of the wood particles, dicing the cable increased disorder at the 1 cm scale. 

43 
Volume Fraction CO ( L/L) 

600 

500 

400 

300 

200 

100 

0 

3000 

2500 

2000 

1500 

1000 

500 

0 

Volume Fraction CO ( L/L) 

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 

Mass Loss 

Figure 15. Comparison of CO production in electrical cable tests in whole (solid 

lines) and diced (dotted lines) configurations. Note the change of ordinate scale 

at mass loss of 50 percent. 

The third set of specimens examined here, the fabric/foam combinations, was by comparison not 

sensitive to either configuration or initial oxygen volume fraction. Figure 16 shows the oxygen 

depletion and CO2 production from tests of whole slabs of foam with initial oxygen volume 

fractions of 0.21 and 0.17. Unlike the bookcase tests, the sofa material tests did not appear to be 

limited by oxygen consumption. The oxygen depletion in either case was essentially the same. 

However, even in the reduced oxygen tests, the oxygen volume fraction never fell to 0.14, the 

limiting volume fraction for the particleboard. One reason for this low oxygen depletion was the 

small size of the sofa specimen (6 g compared to 90 g of bookcase material). Therefore, a larger 

specimen of sofa material might experience some effect from a reduced oxygen test, or if there 

were a larger reduction in the initial volume fraction. It should be noted that the reduced oxygen 

tests did have an effect on CO production, increasing its volume fraction from 500 μL/L to 

750 μL/L. 

Another feature of the sofa material tests was the brief duration of the flaming mode, lasting for 

under 1 min in most cases, compared to 2.5 min for the cable and 2 min to 5 min for the 

bookcase specimens. From Figure 16, it appears that both the oxygen consumption and the CO2 

generation were confined to the later stages of mass loss, behavior not seen with the other 

materials. We suspect that this is primarily a result of a delay on the order of 10s of seconds 

between the burning of the sample material, the flow of the effluent into the exposure chamber, 

and finally the flow to the instrument, that is masked by the longer duration of the flaming mode 

of the other materials. However, it is also possible that a delay exists between the gasification of 

the foam and the oxidation of those gases. 

44 
0 

0.05 

0.1 

0.15 

0.2 

0.25 

Volume Fraction O 2 (L/L) 

0 

0.01 

0.02 

0.03 

0.04 

0.05 

Volume Fraction CO 2 (L/L) 

0% 20% 40% 60% 80% 100% 

Mass Loss 

Figure 16. Comparison of oxygen consumption (top half of figure) and CO2 

production (bottom half of figure) in sofa specimen tests at oxygen volume 

fractions of 0.21 (solid lines) and 0.17 (dotted lines). 

2. HCl and HCN 

The repeatability of the HCl yields (Table 13) from the cable specimens is comparable to the CO 

yields, when allowing for the less precise calculation method for the HCl volume fractions. The 

repeatability of the HCN yields form the sofa material specimens is also reasonable, realizing 

that the signal-to-noise ratio was lower for this combustion product than for CO2, CO, or HCl. 

There is a small possibility that the HCl yields from the diced cable specimens are modestly 

higher than from the intact specimens. Only about one-third of the combustible mass was lost 

during these tests, and HCl is typically generated early in the pyrolysis of PVC. Thus, exposing 

some of the interior PVC surface by dicing the test material might have led to increased HCl 

generation. 

We do not find that any significant differences in HCN yield from the sofa material as a result of 

varying the configuration or oxygen volume fraction. It might appear that dicing the test 

specimens increased the HCN yield, but the yields are all close to the limit of detection and the 

differences should not be overinterpreted. 

45 
 

C. Measured vs. Notional Values 

During sustained and complete combustion, the yield of CO2 should approach its notional values, 

since CO2 is a marker for combusted carbon. This was the case for the sofa specimens, where 

the yields were only about 15 percent below the notional values. The typical residual mass was 

approximately 10 percent of the initial mass, and it appeared to be carbonaceous. 

For the bookcase specimens, the yield of CO2 was about half its notional value. Only about onethird of the specimen mass was consumed, and the residue surface was a carbonaceous char. 

The cable specimens also had CO2 yields that were about half of its notional value. Only about 

one-third of the mass was consumed, and the residue was black and somewhat charred. 

The yields of CO from all the specimens ranged from about 0.02 to 0.05, which corresponds to 

about 2 percent to 5 percent of their notional values. These values are consistent with relatively 

fuel-lean combustion28 and are about five to ten times lower than the CO yields expected of 

postflashover fires.15 

The yields of HCl from the cable specimens approach their notional values. The deficit may 

reflect scavenging by the calcium carbonate filler in the cable jacket. 

The yields of HCl from the bookcase and sofa specimens are 10 percent or less of their notional 

values. Chlorine is present at well under one percent by mass in these two products, so even 

small wall losses in the chimney could have a large effect on the HCl reaching the sampling 

location. 

Very little of the fuel nitrogen appears as HCN. This is as expected from fires that are fuel-lean, 

with the nitrogen probably appearing as molecular nitrogen or nitrogen oxides. 

D. Species Sampling and Measurement 

1. Species Measurement Using FTIR Spectroscopy 

FTIR spectroscopic analysis of combustion products has become fairly common in fire research 

laboratories. However, that does not mean that its use is straightforward. The data from a recent 

round robin involving FTIR measurement of toxic combustion products from a standardized 

apparatus showed interlaboratory variations of up to an order of magnitude. There are 

documents under development in ISO TC92 SC1 and SC3 to standardize the implementation. 

We were able to obtain usable information using this technique. There are a number of lessons 

emerging from this test series that can provide useful input to these efforts, such as the 

following: 

	 The application of FTIR spectroscopy to fire testing requires the constant attention of an 

experienced professional at a level well beyond the demands of the more traditional fire 

test instrumentation. 

46 
	 To maximize the opportunity for obtaining time resolved concentration data, we selected 

a small volume cell of short optical path length and operated without a soot filter. While 

some cleaning was necessary, it was not a major impediment. However, the short path 

length did limit the sensitivity, and moderated our ability to determine toxicologically 

important levels of the major gases. 

	 For future work, a longer path length should be considered. This needs to be 

implemented in the context of burning times as short as one minute, which limits the 

residence time and flow pattern through the cell. 

	 The long, heated lines used here (and recommended in the SAFIR report29 and ISO 

1970230) enabled quantitative collection of HCl, a compound that is generally regarded as 

difficult to determine. 

2. Chimney Sampling 

Some combustion products, such as CO2 and CO, are generated in sufficient quantity and are 

sufficiently stable to be analyzed in the collection chamber. By contrast, the volume fractions of, 

e.g., the acid gases decay rapidly and must be either sampled as they are generated or their 

volume fractions in the collection chamber must be extrapolated back to the time when they first 

enter the chamber. 

For the current experiments, the decision to sample combustion products from within the 

chimney was well intentioned, but was found to have its limitations. The principal caution arose 

from the flames often extending past the sampling point. As a result, the measured volume 

fractions were not necessarily indicative of those to which people might be exposed. 

The limitations of the current location could be mitigated by several approaches, each requiring 

care in its implementation: 

	 The sampling port could be moved above the outlet of the chimney. The location would 

need to be above the reactive zone of the plume from any combustible. It would also 

have to be below the region where the gases begin to be diffused by the uncontrolled flow 

field in the collection chamber. 

	 The chimney could be lengthened such that the flames never extend beyond a sampling 

point located near the top of the chimney. The extent to which the hot walls influenced 

the yields of the toxic combustion products would need to be resolved. 

	 The sensitivity of the FTIR absorption cell could be improved, subject to the volumetric 

limitation mentioned above. 

	 Reducing the volume of the collection chamber could be considered. This would 

increase the volume fractions of the gases and improve the accuracy of any extrapolation 

to the time of generation. A more sophisticated correction would need to be applied to 

the volume fractions in order to reflect the change in molar volume resulting from the 

combustion process. It also appears that the volume reduction needed to obtain a large 

change in the volume fractions would also result in more rapid depletion of oxygen. 

47 
Since the vitiated air is recirculated into the combustion chamber, this more rapid oxygen 

depletion would change the timing of the specimen burning dynamics. 

E. Importance of Undetected Gases 

The equations in ISO 13571 include provision for additional gases to be included in estimating 

the time available for escape or refuge from a fire: HBr, HF, SO2, NO2, acrolein (C3H4O) and 

formaldehyde (H2CO). There was no Br, F, or S in any of the products examined in this project, 

so the first three of these gases were not expected. The presence of the latter three was not 

detected, thus establishing the upper limits of their presence at the volume fractions listed in 

Table 5. 

To put the potential contributions of the sensory irritant gases (HCl, NO2, acrolein, and 

formaldehyde) in context, we use the equations in ISO 13571 for calculating the Fractional 

Effective Dose (FED) for the narcotic gases, CO2 and CO, and the Fractional Effective 

Concentration (FEC) for the four sensory irritant gases. 

The FED equation is: 

 t 2  t 2 

2.36   CO2  CO HCN FED    t  6 t exp   , 

t1 35000 t1 1.2 10  5   

where Δt is the exposure interval in minutes. 

For the volume fractions measured in the chimney, for all three types of specimens, inhalation 

would result in incapacitation in times of the order of 5 min for the bookcase and cable 

specimens (mainly due to CO and CO2), and 1 min for the sofa specimens (mainly due to HCN). 

The FEC equation in ISO 13571 is: 

 HCl  HBr  HF  SO2  NO 2  acrolein  formaldehyde  irritant FEC = 

F F F F F F F HCl HBr HF SO 

       F 2 NO 2 acrolein formaldehyde Ci 

The FEC contributions of the four irritant gases were estimated from their volume fractions in 

the chimney and the incapacitating levels in ISO 13571 (FHCl, etc.). The results are compiled in 

Table 15. 

48 
 

Table 15. Limits of Importance of Undetected Toxicants 

Volume fraction (μL/L) FEC Contribution 

HCl NO2 C3H4O H2CO HCl NO2 C3H4O H2CO 

Incapacitating 

level 1000 250 30 250 

Bookcase 0 to 110 < 40 < 20 < 40 0 to 0.1 < 0.2 < 0.7 < 0.2 

Sofa 0 to 50 < 40 < 20 < 40 0 to 0.05 < 0.2 < 0.7 < 0.2 

Cable 5000 to 

14000 

< 40 < 20 < 40 5 to 14 < 0.2 < 0.7 < 0.2 

It stands out that the FEC contribution from acrolein is as much as two-thirds of an 

incapacitating level. This is because (a) the limit of detection is close to the listed incapacitating 

level and (b) the incapacitating level is very low. While there is agreement among experts that 

this value of 30 μL/L is reasonable, there are data that suggest strongly that this is unnecessarily 

conservative. Kaplan and co-workers exposed individual baboons to various concentrations of 

acrolein in air.31 At the end of 5 min, each baboon was given a signal and could perform an 

action that led to escape from the test chamber. The baboons exposed at up to 500 μL/L escaped 

and survived. Those exposed to higher levels escaped, but died later. These data suggest that 

people should be able to accommodate a nearly instantaneous exposure to, e.g., at least 300 μL/L 

without becoming incapacitated. That would reduce the FEC contribution values in the acrolein 

column to < 0.1. This is consistent with Levin and coworkers, who developed extensive 

information on the effects of gas mixtures on rat lethality and incapacitation.32 They used those 

data to test whether the toxic potency of a small number of gases (not including acrolein, 

formaldehyde, and NO2) could account for the lethality of the effluent from a variety of 

materials. Within the uncertainty in the results,  30 %, there was no need to invoke additional 

toxicants. 

Using this revised contribution of acrolein, the immediate bookcase-generated environment is 

incapacitating from narcotic gases within 5 min and is not incapacitating from the irritant gases. 

Thus, the contributions of the unmeasurable irritant gases do not affect the time to incapacitation. 

As one moves further from the burning object, the FED and FEC both decrease, and the irritant 

contributions become even less important. 

The same analysis applies to the sofa specimens. In fact, for the highest HCN volume fractions, 

the FED would reach unity in as little as 5 s, making the role of the irritant gases less important. 

For the cable specimens, HCl dominates the FEC, and the roles of the other three irritant gases 

are minor. 

49 
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50 
VI. CONCLUSION 

This paper reports toxic gas yield data for specimens cut from three complex combustibles: a 

bookcase, a sofa, and residential electrical power cable. The physical fire model used was the 

radiant apparatus from NFPA 269/ASTM E 1678. This apparatus allows the use of a test 

specimen that approximates the geometry and radiant exposure that might be experienced by the 

intact combustible in a well-ventilated flaming fire. In addition to performing the tests as 

prescribed in the standards, this work examined the effect of varying the initial oxygen 

concentration to approach an underventilated fire, and the effect of dicing the test specimens, to 

estimate the effect of the conformation of the test specimen. 

There were two changes in all the testing. First, the shutter isolating the collection chamber from 

the combustion chamber/chimney was closed immediately upon cessation of flaming. In the 

standard operating procedure, the shutter is closed 15 min into the test. The change minimizes 

the contribution of non-flaming combustion to the measured combustion gas yields. Second, gas 

was extracted from a location in the chimney sampling for FTIR analysis. This was intended to 

decrease the limit of detection for trace gases. 

The findings were as follows: 

	 For operation under the standard test procedure: 

o	 The CO2 yields were quite repeatable and represented between half and 

90 percent of the carbon in the test specimens. All specimens left a black residue 

that was presumably carbon-enriched, offering a (non-quantitative) explanation 

for the yields being below the notional yields. 

o	 The CO yields were generally of lower repeatability than the CO2 yields. 

o	 The HCN yields were below the limit of detection for the bookcase specimens. 

Even for the sofa and cable specimens, the yields were no more than 2 percent of 

the notional yield, based on the conversion of fuel nitrogen. 

o	 The HCl volume fraction measurements were near the limit of detection for the 

bookcase and sofa specimens. For the cable specimens, the yields approached the 

notional yield and were moderately repeatable. 

	 Reducing the initial oxygen volume fraction to 0.17 had no significant effect on the 

yields of CO2, CO, or HCl. The average HCN yield from the intact cable specimens 

(only) was substantially reduced. 

	 With the initial oxygen volume fraction of 0.21, dicing the test specimens had no 

significant effect on the any of gas yields, except for the HCN yield from the cable 

specimens, which was reduced. 

With the initial oxygen volume fraction of 0.17, the only measured effects were an 

increase in the CO yield from dicing the bookcase specimens and an increase in HCN 

yield from dicing the sofa specimens. There was a noticeable difference in the time 

profile of CO release for the bookcase specimens. The CO yields were all substantially 

below the value of 0.2 found in real-scale post-flashover tests. 

51 
The combination of reducing the initial oxygen level and dicing the test specimen might 

have led to an increase in the HCl yield from the cable specimens. 

	 The yields of NO, NO2, acrolein, and formaldehyde were all below their respective limits 

of detection. 

	 Combined, these findings indicate that there can be some sensitivity of the yields and the 

timing of release of the toxic gases to the combustion environment. This sensitivity is 

dependent on the chemistry and conformation of the test materials. 

	 The sensitivity of the short optical path FTIR cell limited the precision of this 

examination. However, there was sufficient information to assess the toxicological 

significance of the variations in the test procedure. 

	 Sampling from the chimney did improve the quantification of the trace gas volume 

fractions. Analysis of the results would be simplified by identifying a sampling point 

further downstream at which chemical reactivity of the products had been completed but 

before which extensive dilution had occurred. 

	 Calculation of the contributions of the gases to incapacitation of people who might be 

exposed to these environments showed: 

o	 For the bookcase material, incapacitation would results from inhalation of CO and 

CO2. 

o	 For the sofa material, incapacitation would result from inhalation of HCN. 

o	 For the cable material, incapacitation would result from exposure to HCl. 

If the CO yield were at the expected postflashover value of 0.2, 

o	 For the bookcase material, incapacitation would result from inhalation of CO and 

CO2. 

o	 For the sofa material, incapacitation would result from inhalation of CO, HCN 

and CO2. 

o	 For the cable material, incapacitation would result from inhalation of CO and 

CO2, perhaps with some contribution from exposure to HCl. 

52 
VII. ACKNOWLEDGMENTS 

The authors express their appreciation to Michael Selepak for his assistance in performing the 

tests. David Mercier of Southwire, Inc. provided useful information on the formulation of the 

cable. Schwartzkopf Laboratories performed the elemental and thermal analyses of the 

combustibles. 

53 
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54 
REFERENCES 

1. Phillips, W.G.B., Beller, D.K., and Fahy, R.F., “Computer Simulation for Fire Protection 

Engineering,” Chapter 5-9 in SFPE Handbook of Fire Protection Engineering, 4th Edition, 

P.J. DiNenno et al., eds., NFPA International, Quincy, MA, 2008. 

2. http://www.nist.gov/el/fire_research/cfast.cfm. 

3. Peacock, R. D., Jones, W. W., and Reneke, P. A., “CFAST – Consolidated Model of Fire 

Growth and Smoke Transport (Version 6): Software Development and Evaluation Guide,” 

Natl. Inst. Stand. Technol., Special Publication 1086, (2013) 

4. Peacock, R.D., Jones, W.W., and Bukowski, R.W., “Verification of a Model of Fire and 

Smoke Transport,” Fire Safety Journal 21, 89-129, (1993). 

5. http://fire.nist.gov/fds. 

6. “Fire Dynamics Simulator (Version 5): Technical Reference Guide,” 4 volumes, NIST Special 

Publication 1018-5; National Institute of Standards and Technology, Gaithersburg, MD, 

(2010). 

7. “Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products 

Using an Oxygen Consumption Calorimeter,” ASTM E1354-04a, ASTM International, West 

Conshohocken, PA, 2004. 

8. See, e.g., “Standard for the Flammability (Open Flame) of Mattress Sets,” 16 CFR Part 1633, 

Federal Register 70 (50), 13471-13523, 2006. 

9.http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_tc_browse.htm?commid=50540& 

published=on&development=on. 

10. “Life-threatening Components of Fire – Guidelines for the Estimation of Time to 

Compromised Tenability in Fires,” ISO 13571, International Standards Organization, Geneva, 

2012. 

11. "Guidelines for Assessing the Fire Threat to People," ISO 19706, International Standards 

Organization, Geneva, 2011. 

12. Gann, R.G., Babrauskas, V., Peacock, R.D., and Hall, Jr., J.R., "Fire Conditions for Smoke 

Toxicity Measurement," Fire and Materials 18, 193-199 (1994). 

13. "Guidance for Comparison of Toxic Gas Data between Different Physical Fire Models and 

Scales," ISO 29903, International Standards Organization, Geneva, 2012. 

14. “Standard Test Method for Developing Toxic Potency Data for Use in Fire Hazard 

Modeling,” NFPA 269, NFPA International, Quincy, MA, 2012. 

15. “Standard Test Method for Measuring Smoke Toxicity for Use in Fire Hazard Analysis,” 

ASTM E1678-10, ASTM International, West Conshohocken, PA, 2010. 

16. (a) Gann, R.G., Averill, J.D., Nyden, M.R., Johnsson, E.L., and Peacock, R.D., “Smoke 

Component Yields from Room-scale Fire Tests,” NIST Technical Note 1453, National 

Institute of Standards and Technology, Gaithersburg, MD, 159 pages (2003). 

(b) Gann, R.G., Averill, J.D., Nyden, M.R., Johnsson, E.L., and Peacock, R.D., “Fire Effluent 

55 
Component Yields from Room-scale Fire Tests,” Fire and Materials 34, 285-314, (2010), 

DOI: 10.1002/fam.1024. 

17. Ohlemiller, T.J., and Villa, K., “Furniture Flammability: An Investigation of the California 

Bulletin 133 Test. Part II: Characterization of the Ignition Source and a Comparable Gas 

Burner,” NISTIR 4348, National Institute of Standards and Technology, Gaithersburg, MD, 

1990. 

18. Levin, B. C.; Braun, E.; Navarro, M.; Paabo, M., “Further Development of the N-Gas 

Mathematical Model: An Approach for Predicting the Toxic Potency of Complex Combustion 

Mixtures, in Nelson, G. L., ed., Fire and Polymers II: Materials and Tests for Hazard 

Prevention, ACS Symposium Series No. 599, pp. 293-311, American Chemical Society, 

Washington, DC, 1995. 

19. Kaplan, H.L., Grand, A.F., and Hartzell, G.E., Combustion Toxicology: Principles and Test 

Methods, Technology Publishing Co., Lancaster, PA, 1983. 

20. "Guidance for Evaluating the Validity of Physical Fire Models for Obtaining Fire Effluent 

Toxicity Data for Use in Fire Hazard and Risk Assessment – Part 2: Evaluation of Individual 

Physical Fire Models," ISO/TR 16312-2, International Standards Organization, Geneva, 2007. 

21. "Controlled Equivalence Ratio Method for the Determination of the Hazardous Components 

of Fire Effluent," ISO/TS 19700, International Standards Organization, 2010. 

22. "Reaction-to-fire Tests – Heat Release, Smoke Production, and Mass Loss Rates – Part 1: 

Heat Release (Cone Calorimeter Method)," ISO 5660-1, International Standards Organization, 

Geneva, 2002. 

23. "Plastics — Smoke Generation — Part 2: Determination of Optical Density by a Singlechamber Test, ISO 5659-2, International Standards Organization, Geneva,1994. 

24. Babrauskas, V., Harris, Jr., R.H., Braun, E., Levin, B.C., Paabo, M., and Gann, R.G., "The 

Role of Bench-Scale Test Data in Assessing Real-Scale Fire Toxicity," Technical Note 1284, 

National Institute of Standards and Technology, 1991. 

25. Haaland, D.M.; Easterling, R.G.; and Vopicka, D.A., “Multivariate Least-Squares Methods 

Applied to the Quantitative Spectral Analysis of Multicomponent Samples” Applied 

Spectroscopy 39, 73-84, (1985), doi:10.1366/0003702854249376. 

26. Gas Phase Infrared Spectral Standards, Revision B, Midac Corp.; Irvine, CA (1999). 

27. Speitel, L.C., “Fourier Transform Infrared Analysis of Combustion Gases,” Federal Aviation 

Administration Report DOT/FAA/AR-01/88, 2001. 

28. Pitts, W.M., "The Global Equivalence Ratio Concept and the Formations Mechanisms of 

Carbon Monoxide in Fires," Progress in Energy and Combustion Science 21, 197-237, 

(1995). 

29. "Smoke Gas Analysis by Fourier Transform Infrared Analysis,: The SAFIR Project," VTT 

Research Note, Technical Research Centre of Finland, 81 Pages, 1999. 

56 
30. “Toxicity testing of fire effluents -- Guidance for analysis of gases and vapours in fire 

effluents using FTIR gas analysis” ISO 19702, International Standards Organization, Geneva, 

2006. 

31. Kaplan, H.L., Grand, A.F., Switzer, W.G., Mitchell, D.S., Rogers, W.R., and Hartzell, G.E., 

"Effects of Combustion Gases on Escape Performance of the Baboon and the Rat," Journal of 

Fire Sciences 3, 228-244, (1985). 

32. Levin, B. C.; Braun, E.; Navarro, M.; Paabo, M., “Further Development of the N-Gas 

Mathematical Model: An Approach for Predicting the Toxic Potency of Complex 

Combustion Mixtures,” American Chemical Society. Fire and Polymers II: Materials and 

Tests for Hazard Prevention. National Meeting, 208th. Chapter 20. ACS Symposium Series 

No. 599. August 21-26, 1994, Washington, DC, American Chemical Society, Washington, 

DC, Nelson, G. L., Editor, pp. 293-311, 1995. 

57