NIST Technical Note 1762 

Smoke Component Yields from Benchscale Fire Tests: 3. ISO 5660-1 / ASTM 

E 1354 with Enclosure and Variable 

Oxygen Concentration 

Nathan D. Marsh 

Richard G. Gann 

http://dx.doi.org/10.6028/NIST.TN.1762 

 

NIST Technical Note 1762
 

Smoke Component Yields from Benchscale Fire Tests: 3. ISO 5660-1 / ASTM 

E 1354 with Enclosure and Variable 

Oxygen Concentration 

Nathan D. Marsh 

Richard G. Gann 

Fire Research Division 

Engineering Laboratory 

http://dx.doi.org/10.6028/NIST.TN. 1762 

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 1762
 

Natl. Inst. Stand. Technol. Tech. Note 1762, 43 pages (December 2013) 

http://dx.doi.org/10.6028/NIST.TN. 1762 

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 presents 

examination of the fourth 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 ISO 5660-1 

/ ASTM E 1354 cone calorimeter, modified to have an enclosure and a gas delivery system 

allowing variable oxygen concentration. The test specimens was 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 cable. Initially, the 

standard test procedure was followed. Subsequent variation in the procedure included reducing 

the supplied oxygen volume fraction to 0.18, 0.16, and 0.14, reducing the incident heat flux to 

25 kW/m2

, and reducing the gas flow rate by half. 

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, performing the tests at the reduced oxygen volume fraction led to small 

increases on the toxic gas yields. The exceptions were an increase in the CO yield for the 

bookcase at 0.14 oxygen volume fraction. Reducing the incident heat flux had little effect on the 

toxic gas yields, other than increasing variability. Reducing the gas flow rate reduced the limits 

of detection by half, but also resulted in reduced gas yields at lower oxygen volume fractions. 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................................................................................................................................................3
 

D. PHYSICAL FIRE MODELS........................................................................................................................................5
 

II. EXPERIMENTAL INFORMATION ................................................................................................................. 7
 

A. SUMMARY OF ISO 5660‐1 / ASTM E 1354 APPARATUS.....................................................................................7
 

1. Hardware .....................................................................................................................................................7
 

2. Gas Sampling and Analysis Systems.............................................................................................................8
 

B. OPERATING PROCEDURES ..............................................................................................................................11
 

1. "Standard" Testing.....................................................................................................................................11
 

2. Test Specimens...........................................................................................................................................12
 

3. Test Procedure Variation............................................................................................................................12
 

C. DATA COLLECTION..........................................................................................................................................13
 

III. CALCULATION METHODS..........................................................................................................................15
 

A. MASS LOSS RATE .............................................................................................................................................15
 

B. NOTIONAL GAS YIELDS....................................................................................................................................15
 

C. CALCULATED GAS YIELDS ................................................................................................................................15
 

1. CO and CO2 .................................................................................................................................................15
 

2. HCl and HCN...............................................................................................................................................16
 

3. Other Gases................................................................................................................................................17
 

IV. RESULTS...................................................................................................................................................19
 

A. TESTS PERFORMED .........................................................................................................................................19
 

B. CALCULATIONS OF TOXIC GAS YIELDS WITH UNCERTAINTIES.........................................................................26
 

V. DISCUSSION.............................................................................................................................................29
 

A. OVERALL TEST VALUES....................................................................................................................................29
 

B. SPECIMEN PERFORMANCE AND TEST REPEATABILITY....................................................................................29
 

1. CO2 and CO.................................................................................................................................................29
 

2. HCl and HCN...............................................................................................................................................31
 

C. MEASURED VS. NOTIONAL VALUES ................................................................................................................34
 

D. SPECIES SAMPLING AND MEASUREMENT ......................................................................................................35
 

1. Species Measurement Using FTIR Spectroscopy ........................................................................................35
 

E. IMPORTANCE OF UNDETECTED GASES ...........................................................................................................35
 

VI. CONCLUSIONS..........................................................................................................................................39
 

VII. ACKNOWLEDGEMENTS .........................................................................................................................40
 

REFERENCES ...............................................................................................................................................................41
 

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LIST OF FIGURES 

FIGURE 1. MODIFIED CONE CALORIMETER ..............................................................................................................................8
 

FIGURE 2. FTIR SPECTRUM OF COMBUSTION PRODUCTS FROM A CABLE SPECIMEN ......................................................................10
 

FIGURE 3. COMPARISON OF FTIR AND NDIR MEASUREMENTS OF CO VOLUME FRACTION ............................................................16
 

FIGURE 4. EFFECT OF OXYGEN CONCENTRATION ON CO YIELDS, BOOKCASE (DASHED LINE = REDUCED FLOW). ERROR BARS ARE ± THE
 

STANDARD DEVIATION OF YIELDS FROM MULTIPLE RUNS..................................................................................................30
 

FIGURE 5. EFFECT OF OXYGEN CONCENTRATION ON CO YIELDS, SOFA (DASHED LINE = REDUCED FLOW). ERROR BARS ARE ± THE
 

STANDARD DEVIATION OF YIELDS FROM MULTIPLE RUNS..................................................................................................30
 

FIGURE 6: EFFECT OF OXYGEN CONCENTRATION ON CO YIELDS, CABLE (DASHED LINE = REDUCED FLOW). ERROR BARS ARE ± THE
 

STANDARD DEVIATION OF YIELDS FROM MULTIPLE RUNS..................................................................................................31
 

FIGURE 7. HCN VOLUME FRACTIONS, SOFA, 50 KW/M2

, 12.5 L/S, 16 % O2 BY VOLUME. UNCERTAINTY IS 10 % OF THE REPORTED HCN
 

VOLUME FRACTION .................................................................................................................................................32
 

FIGURE 8. EFFECT OF OXYGEN CONCENTRATION ON HCN YIELDS, SOFA. ERROR BARS ARE ± THE STANDARD DEVIATION OF YIELDS FROM
 

MULTIPLE RUNS ......................................................................................................................................................32
 

FIGURE 9. HCL VOLUME FRACTIONS, CABLE, 50 KW/M2

, 12.5 L/S, 16 % O2 BY VOLUME. UNCERTAINTY IS 10 % OF THE REPORTED
 

VOLUME FRACTION. ................................................................................................................................................33
 

FIGURE 10. EFFECT OF OXYGEN CONCENTRATION ON YIELDS OF HCL, CABLES. ERROR BARS ARE ± THE STANDARD DEVIATION OF YIELDS
 

FROM MULTIPLE RUNS..............................................................................................................................................34
 

LIST OF TABLES 

TABLE 1. ELEMENTAL ANALYSIS OF FUEL COMPONENTS.............................................................................................................4
 

TABLE 2. SPECIES AND FREQUENCY WINDOWS FOR FTIR ANALYSIS............................................................................................11
 

TABLE 3. CALCULATED NOTIONAL YIELDS OF TOXIC PRODUCTS FROM THE TEST SPECIMENS. ..........................................................15
 

TABLE 4. DATA FROM BOOKCASE MATERIAL TESTS .................................................................................................................20
 

TABLE 5. DATA FROM SOFA MATERIAL TESTS ........................................................................................................................21
 

TABLE 6. DATA FROM CABLE MATERIAL TESTS .......................................................................................................................22
 

TABLE 7. GAS YIELDS FROM BOOKCASE MATERIAL TESTS .........................................................................................................23
 

TABLE 8. GAS YIELDS FROM SOFA MATERIAL TESTS.................................................................................................................24
 

TABLE 9. GAS YIELDS FROM CABLE MATERIAL TESTS ...............................................................................................................25
 

TABLE 10. YIELDS OF COMBUSTION PRODUCTS FROM CONE CALORIMETER TESTS........................................................................26
 

TABLE 11. FRACTIONS OF NOTIONAL YIELDS..........................................................................................................................28
 

TABLE 12. LIMITS OF IMPORTANCE OF UNDETECTED TOXINS......................................................................................................36
 

TABLE 13. LIMITS OF IMPORTANCE OF UNDETECTED TOXICANTS................................................................................................37
 

vi 
 

 

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 

studies,3 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 predictions.5 

These models calculate the 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 calorimeter6 and larger scale apparatus7, which are routinely 

used to generate information on the rate 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.8 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.9 

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. 

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 

1 
 

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.10 

An analysis of the U.S. fire fatality data11 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.12 If both the mass of the test specimen and the mass 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.13,14 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 harmful 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. 

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: 

2 
	 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 15. Following this recap are the details of the tests using 

the fourth 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. 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 

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, 

3 
this fuel would be a source of CO2, CO, HCN, HCl, and partially combusted organics. 

The ignition source was the California TB133 propane ignition burner16 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 facing 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 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 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. More details regarding the elemental analysis can be found in NIST TN 176017 . The 

elemental composition of the component materials in the fuels is shown in Table 1. 

Table 1. Elemental Analysis of Fuel Components. 

Sample C H N Cl P O 

Bookcase 0.481  0.6 % 0.062  0.8 % 0.029  13 % 0.0030  4 % NA 0.426  1 % 

Sofa 0.545  1 % 0.080  1 % 0.100  1 % 0.0068  16 % 0.0015  17 % 0.267  4 % 

Cable 0.576  0.5 % 0.080  1.5 % 0.021  6 % 0.323  0.4 % NA NA 

The uncertainties are the standard deviation of three elemental analysis tests, combined with the 

uncertainty of the mass fraction of individual material components, i.e. fabric vs. foam for the 

sofa. 

4 
D. PHYSICAL FIRE MODELS 

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

components of the combustion effluent.18,19 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 1970020) and is 

considering standardization of another, the cone calorimeter (ISO 5660-121) 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 5659-222). 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. 

In related work, we report toxic gas measurements in the NFPA 269 toxicity test method,17 the 

ISO/TS 19700 tube furnace23, and the smoke density chamber.24 

The modification of the cone calorimeter to measure gas yields in vitiated environments was first 

introduced in the early 1990s25—27 and has recently received renewed interest.28 —30 The more 

recent work has focused on the effect of secondary oxidation on the heat release rate 

measurement, and progress on measuring chemical species is just beginning. 

5 
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6 
II. EXPERIMENTAL INFORMATION 

A. SUMMARY OF ISO 5660-1 / ASTM E 1354 APPARATUS 

1. Hardware 

The standard apparatus consists of a load cell, specimen holder, truncated cone electrical 

resistance heater, spark igniter, canopy hood, and exhaust ductwork. The electrical heater is 

calibrated using a Schmidt-Boelter heat flux gauge, which itself is calibrated using a 

standardized source linked to a primary calibration standard. Exhaust flow in the duct is 

normally controlled by a variable-speed fan of the “squirrel cage” design, and measured by 

measuring the pressure drop across an orifice plate installed downstream from the fan, along 

with the temperature at that location. 

Under standard operation, the heat release rate is measured via oxygen consumption calorimetry, 

thus the oxygen concentration in the exhaust must be measured. See the following section for 

more detail. 

For this work, the apparatus was modified to include 1) an enclosure measuring 430 mm by 

500 mm by 570 mm high, constructed of aluminum framing and polycarbonate walls (insulated 

in the locations of highest heat flux with aluminum foil), which seals against the underside of the 

canopy hood, and 2) a gas delivery system capable of delivering at 25 L/s a mixture of air and 

nitrogen. This consisted of a self-pressurizing 180 L liquid nitrogen dewar and a 120 psi supply 

of filtered “house” air. A standard CGA 580 regulator on gas outlet of the dewar maintained 

pressure at 80 psi, and was connected to a control manifold by 13 mm diameter copper tubing. 

Valves on the manifold allowed individual control of both the nitrogen gas and the compressed 

air, which were metered by 3 high-capacity rotameters (2 in parallel for air and one for nitrogen). 

The rotameters were then connected to a gas mixing chamber constructed out of 400 mm by 

60 mm tube, with 2 air and 2 nitrogen inlets on one end and 4 mixed gas outlets on the other. 

These outlets were then each connected by more 13 mm tubing to each side of the enclosure at 

the base frame. The interior edges of this (hollow) aluminum frame were perforated on each side 

by 5 equally spaced holes, 6.4 mm diameter, providing an even supply of gas around the 

perimeter at the base of the enclosure. Some features of this setup can be seen in Figure 1. 

One face of the enclosure includes a latchable door (20 cm square) for loading and unloading the 

test specimen. In order to allow time for the desired gas mixture to expel air introduced during 

specimen loading, a shutter composed of ceramic board supported by a metal frame and slide 

mechanism was placed between the specimen and the cone heater. Attached to the shutter was a 

rod extending through a bulkhead fitting in the enclosure wall so that the shutter could be 

withdrawn to commence a test. During operation, balancing of the gas supply and the exhaust 

was accomplished by observing a small perforation in the enclosure provided with soap film, 

while monitoring the recorded volumetric flow rate calculated from the pressure differential 

across the orifice plate in the exhaust duct. 

7 
 Figure 1. Modified Cone Calorimeter 

Although not discussed here, the heat release rate measurement was calibrated daily using a 

5 kW methane burner, itself calibrated by measuring the gas flow using a piston-type primary 

standard calibrator, accurate to 1 % of the reading. 

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 

Sampling for this instrument was pulled from the exhaust duct upstream from the exhaust fan, 

using a perforated ring sampling probe. The flow passed through a large volume cartridge filter, 

8 
 

 

through two parallel membrane HEPA filters, through an electrical chiller maintained at -2 oC to 

-5 oC, and finally through a fixed bed of calcium sulfate desiccant. The stream sent to the O2 

analyzer also passed through a fixed bed of sodium hydroxide-coated silica particles. The flows 

were maintained at 3 L/min. The analyzer itself was calibrated daily with zero and span gases (a 

mixture of 2800 μL/L CO and 0.028 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. 

The concentrations of CO and the additional six toxic gases were measured using a Bruker 

Fourier transform infrared (FTIR) spectrometer* equipped with an electroless nickel plated 

aluminum flow cell (2 mm thick KBr windows and a 1 m optical pathlength) with an internal 

volume of 0.2 L, maintained at (170 ± 5) °C. Samples were drawn through a heated 6.35 mm 

(1⁄4 in.) stainless steel tube from inside the exhaust duct, upstream of the exhaust, with its tip at 

approximately the centerline. The sample was pulled through the sampling line and flow cell by 

a small pump located downstream from the flow cell. There were no traps or filters in this 

sampling line. The pump flow was measured at 4 L/min maximum, but was at times lower due 

to fouling of the sampling lines with smoke deposits. 

Although this instrument has a longer path length and is therefore more sensitive than the one 

used in our previous studies, the “batch” nature of a cone calorimeter experiment along with the 

continuous flow of the exhaust requires instantaneous data collection, in this case at 0.17 Hz, that 

did not allow for data averaging to improve the signal-to-noise. Therefore, the limits of 

detection are essentially unchanged from the previous studies. The implications of this will be 

discussed in Section V. 

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

Figure 2. 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. 

*

 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. 

9 
4500 4000 3500 3000 2500 2000 1500 1000 500

Wavenumber (cm‐1)

H2O H2O

CO

CO2

CO2

HCl

CO2

Figure 2. FTIR Spectrum of Combustion Products from a Cable Specimen 

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.31 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 Midac32 and 

from a collection of spectra provided the Federal Aviation Administration who performed benchscale fire tests on similar materials.33 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 2. 

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 MDL values reported in Table 2 

10 
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 real 

limits of detection for these two compounds are an order of magnitude 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. 

Table 2. 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 near 20 min for the bookcase specimens, 1 to 3 min for the sofa specimens, and 2 to 4 min 

for the cable 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 1 s to the FTIR analyzer. These delay times are long enough to allow for a small 

degree of axial diffusion. However, since our analysis integrates the data over time, this did not 

adversely affect the quantification of total gas evolved. 

B. OPERATING PROCEDURES 

1. "Standard" Testing 

The intent was to test specimens of each of the three types under normal and reduced-oxygen 

conditions, two incident heat fluxes, and two gas flow rates. The steps in the procedure are: 

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

performed daily). 

	 Establish the desired gas flow rates and oxygen concentration, with an empty specimen 

holder in place. 

11 
	 Turn on the gas sampling data collection and establish background data for the 

combustion product concentrations. 

	 Open the chamber door. 

	 Replace the empty specimen holder with one containing the specimen. 

	 Close the chamber door. 

	 Wait for the oxygen concentration to return to its established value. 

	 Withdraw the shutter and insert the spark igniter. 

	 Turn on the spark igniter. 

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

	 Collect concentration data until a steady state of pyrolysis is reached. 

	 Open the chamber door; remove the specimen; close the chamber door. 

	 Record a post-test background to account for any drift. 

	 Weigh any specimen residue. 

As in the previous work, the bookcase material underwent considerable pyrolyzing after the 

flames disappeared. However, as the cone calorimeter is a continuous-flow apparatus, no 

physical steps were necessary to isolate the pyrolysis results from the flaming results, and the 

transition between the two is clearly visible in the data, e.g. the differential of the mass loss data. 

2. Test Specimens 

The specimens were intended to approximate the full item. Specimen size was mostly limited by 

the size of the specimen holder, although in the case of the cables it was not necessary to 

completely fill the pan or use multiple layers. Instead the number of cables was chosen to 

produce similar gas concentrations and heat release rates compared to the other two types of 

specimens. The bookcase specimens were single, 10 cm x 10 cm pieces of the particle board, 

with the vinyl surface facing up. The sofa specimens were each a single piece of foam, 10 cm by 

10 cm by 1 cm thick, covered with a single piece of the polyester/cotton cover fabric, 10.5 cm x 

10.5 cm, on the upper (exposed) surface (the fabric being slightly oversized so that it could be 

“tucked” in around the edges of the foam). The cable specimens were five 10 cm lengths of 

cable cut from the spool and placed side-by-side. All specimens were wrapped on the bottom 

and sides with aluminum foil, which was cut to be flush with the top surface of the specimen. 

The specimen holder was lined with a refractory aluminosilicate blanket, adjusted in thickness so 

that each specimen was the same distance from the upper surface to the cone heater assembly 

(28 mm). Note that with the exception of area dimensions, these specimens were prepared 

almost identically to those in Ref. 17, and are therefore not reproduced here. Also, in our prior 

work we found little to no impact from “dicing” the specimens, i.e. cutting them into small 

pieces, and therefore did not investigate that effect here. 

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 examination of the potential for an 

12 
improved relationship with the yield data from the room-scale tests, as well as an indication of 

the sensitivity of the gas yields to the specified operating conditions 

	 Variation in incident heat flux between 20 kW/m2 and 50 kW/m2, to determine the 

significance on evolved gases. 

	 Variation of the available oxygen volume fraction from 21 % to 14 %, to more closely 

approach the post-flashover conditions that occurred in the room-scale tests. During preflashover burning, the air entrained by a fire has an oxygen volume fraction of nominally 

0.21. This fraction is lower for post-flashover fires. As part of this work it was 

determined that combustion was barely sustainable at an oxygen volume fraction of 0.14. 

	 Variation of overall gas flow rate from 25 L/s to 12.5 L/s in order to increase sensitivity 

in gas measurements, and to allow the reduction of oxygen volume fraction to 0.14, 

which was difficult in our system at the higher flow. A known drawback to reducing the 

flow is that the sensitivity of the flow measurement, via the pressure drop across the 

orifice plate, is reduced. (This can be ameliorated by installing a smaller orifice so that 

the pressure drop in brought back up to the optimal range of the pressure sensor.) 

C. DATA COLLECTION 

The signals from the load cell, temperature, and pressure needed for ISO 5660-1, and from the 

fixed gas analyzer were recorded on a personal computer using a custom-made data acquisition 

system based on National Instruments data acquisition hardware. Values were recorded at 1 s 

intervals. The FTIR spectra were recorded using the software package provided by the 

manufacturer. Spectra were recorded every 6 s. 

13 
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14 
III. CALCULATION METHODS 

A. MASS LOSS RATE 

The specimen mass loss during a test was determined from the initial reading from the load cell 

and from a point where the specimen transitioned from burning to pyrolyzing, which was 

characterized by a sudden drop in the mass loss rate (derivative of the mass loss calculated over 

16 data points / seconds). The uncertainty in the mass loss, derived from the uncertainties in 

these two measurements, was 0.1 g. 

B. NOTIONAL GAS YIELDS 

The notional, or maximum possible, gas yields (Table 3) 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 1) 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.15 The sofa specimen had a mass ratio of fabric to foam that 

differed modestly from the intact sofas. 

Table 3. Calculated Notional Yields of Toxic Products from the Test Specimens. 

Notional Yields 

Gas Bookcase Cable Sofa 

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. For the cuttings from the sofas, 

the uncertainty in the notional yields was increased by the small variability (estimated at 

3 percent) in the relative masses of the fabric and padding materials in the test specimens. 

C. CALCULATED GAS YIELDS 

1. CO and CO2 

Yields of CO and CO2 were calculated using the measured gas concentrations from the NDIR 

instrument, the measured flows in the exhaust, the exhaust temperature, (accounting for the 

15 
     

background concentrations in room air), the consumed mass of the fuel, and the ideal gas law. 

Concentrations were converted to mass flow, then integrated numerically (rectangular) over the 

time of flaming combustion. 

As we observed previously,17 the CO2 absorption band in the FTIR is saturated at normal volume 

fractions and is therefore highly non-linear. As both the FTIR and NDIR measurements were 

taken from the same location, it was not necessary to measure the CO2 concentration by FTIR. 

Figure 3 shows a comparison of the maximum CO volume fractions measured by the two 

instruments. The FTIR consistently found a lower volume fraction than the NDIR above 

300 μL/L. This is likely due to the non-linearity inherent in IR spectra at higher absorption. 

Since the spectrometer used in this study had a path length that was 10 times that used in the 

previous work,17,23,24 it is not unreasonable that these data fall more in the non-linear range. 

Therefore, the data reported here for CO are taken from the NDIR results. 

0

100

200

300

400

500

600

700

800

0 200 400 600 800

COVolume Fraction (L/L) ‐FTIR

COVolume Fraction (L/L) ‐ NDIR

Figure 3. Comparison of FTIR and NDIR Measurements of CO Volume Fraction 

2. HCl and HCN 

The only calculable HCN yields were from the sofa specimens. The only calculable HCl yields 

were from the cable specimens. FTIR spectra from these experiments were analyzed as 

described in section II.A.2. This analysis normally includes an uncertainty of 10 % of the 

reported value. Volume fractions were converted into mass flows using the flow and 

temperature data, then numerically integrated over the period of flaming combustion. Because 

16 
these data are more sparse than those from the NDIR (0.17 Hz vs. 1.0 Hz) a trapezoidal 

integration was used. We considered the possibility that these results suffered from the same 

non-linear relation between absorption and concentration that occurred with the CO 

measurements. However, since the HCN concentrations were quite low, and the HCl yields were 

reasonably close to their notional yields (see Table 11) and similar to the previous work using a 

different instrument with a shorter path length,17,23,24 we determined that non-linear effects were 

not significant. Furthermore, because the lower heat flux did not, by any other indication, have a 

significant impact on gas yields, other than increased variability, the quantification of FTIR data 

from these runs was omitted. 

3. Other Gases 

The volume fractions of the other toxic gases were always below the detection limit. Thus, the 

upper limits of the yields of these gases were estimated using their limits of detection. 

17 
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18 
IV. RESULTS 

A. TESTS PERFORMED 

The following is the test numbering key, with format F(2)-q-[O2]-N, where 

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

(2): present for the 12.5 L/s flow rate, absent for the 25 L/s flow rate 

q: heat flux per unit area (kW/m2

) 

[O2] Approximate initial oxygen volume percent in the supply gas 

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

Table 4 through Table 9 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. Volume fractions represent 

the maximum value in the test, usually soon after ignition. A yield number in red indicates a 

potential outlier that, if discarded, could improve the repeatability under those conditions. 

The horizontal shaded bands highlight groups of replicate tests. 

19 
 

  

         

         

         

         

         

         

         

         

         

         

         

         

         

         

         

Table 4. Data from Bookcase Material Tests 

NDIR 

Code Specimen 

Mass (g) 

Δm 

(g) 

Δt (s) 

Flaming 

FCO2 

(L/L) 

FCO 

(L/L) 

FO2 

(L/L) 

b‐50‐21‐1 149.8 106.0 1068 0.0065 120 0.2037

b‐50‐21‐2 135.6 105.2 1090 0.0067 140 0.2033

b‐50‐21‐3 138.4 103.7 1043 0.0072 150 0.2028

b‐50‐18‐1 136.0 103.8 1110 0.0070 160 0.1731

b‐50‐18‐2 137.4 101.5 1060 0.0070 160 0.1730

b‐50‐18‐3 138.1 102.1 1110 0.0064 160 0.1748

b‐50‐16‐1 119.2 98.4 993 0.0066 140 0.1559

b‐50‐16‐2 136.6 101.7 1115 0.0062 170 0.1545

b‐50‐16‐3 120.6 91.6 940 0.0062 150 0.1548

b2‐50‐21‐1 131.5 99.6 1110 0.0121 240 0.1974

b2‐50‐21‐2 130.2 97.3 1010 0.0123 230 0.1972

b2‐50‐21‐3 127.4 96.9 1040 0.0124 230 0.1970

b2‐50‐16‐1 131.6 99.7 1140 0.0106 250 0.1504

b2‐50‐16‐2 128.2 97.3 1050 0.0103 230 0.1495

b2‐50‐16‐3 123.8 93.8 1070 0.0103 230 0.1499

b2‐50‐14‐1 129.7 95.7 1170 0.0099 850 0.1285

b2‐50‐14‐2 132.2 98.1 1160 0.0100 450 0.1297

b2‐50‐14‐3 131.6 98.2 1200 0.0101 460 0.1298

b‐25‐21‐1 124.6 93.3 1295 0.0053 180 0.2051

b‐25‐21‐3 128.6 103.0 1590 0.0057 200 0.2046

b‐25‐21‐4 138.8 102.5 1590 0.0058 190 0.2045

b‐25‐18‐1 126.6 34.6 590 0.0045 220 0.1675

b‐25‐18‐2 127.4 30.3 540 0.0043 280 0.1773

b‐25‐18‐3 130.9 54.5 620 0.0042 200 0.1593

b‐25‐18‐4 122.5 32.2 550 0.0041 190 0.1769

b‐25‐16‐1 128.4 26.9 620 0.0037 210 0.1578

b‐25‐16‐2 129.6 21.9 450 0.0037 230 0.1594

b‐25‐16‐3 128.6 25.8 520 0.0032 220 0.1590

20 
 

  

                 

                 

                 

             

           

             

Table 5. Data from Sofa Material Tests 

NDIR FTIR 

Code Specimen 

Mass (g) 

Δm 

(g) 

Δt (s) 

Flaming 

FCO2 

(L/L) 

FCO 

(L/L) 

FO2 

(L/L) 

FCO 

(L/L) 

FHCN 

(L/L) 

s‐50‐21‐1 12.0 8.5 62 0.0071 290 0.2012 260 80

s‐50‐21‐2 11.8 8.5 65 0.0074 310 0.2007 310 90

s‐50‐21‐3 11.7 8.7 66 0.0076 310 0.2007 300 90

s‐50‐18‐1 12.4 8.6 82 0.0067 370 0.1727 290 150

s‐50‐18‐2 11.8 8.5 125 0.0064 330 0.1730 270 130

s‐50‐18‐3 11.9 8.6 105 0.0066 380 0.1727 300 170

s‐50‐16‐1 12.2 8.7 115 0.0068 470 0.1522 380 270

s‐50‐16‐2 12.1 8.4 110 0.0067 420 0.1524 370 250

s‐50‐16‐3 12.3 9.0 120 0.0071 430 0.1527 340 230

s2‐50‐21‐1 11.5 8.5 85 0.0149 520 0.1903 390 210

s2‐50‐21‐2 11.8 8.7 100 0.0120 480 0.1944 400 180

s2‐50‐21‐3 11.8 8.7 90 0.0138 510 0.1919 390 170

s2‐50‐16‐1 10.6 7.7 100 0.0119 500 0.1445 360 330

s2‐50‐16‐2 11.7 8.6 130 0.0102 640 0.1485 460 380

s2‐50‐16‐3 11.7 8.6 120 0.0106 770 0.1481 570 460

s2‐50‐14‐1 11.2 8.0 120 0.0105 440 0.1265 370 110

s2‐50‐14‐2 11.7 8.5 120 0.0104 510 0.1266 380 180

s2‐50‐14‐3 11.9 8.5 120 0.0115 670 0.1252 470 250

s‐25‐21‐1 12.4 8.5 150 0.0059 170 0.2041

s‐25‐21‐2 12.1 6.4 115 0.0054 160 0.2045

s‐25‐21‐3 12.2 8.1 170 0.0055 170 0.2044

s‐25‐18‐1 12.2 5.3 165 0.0043 130 0.1758

s‐25‐18‐2 12.2 5.5 150 0.0045 130 0.1756

s‐25‐18‐3 12.3 5.0 110 0.0049 180 0.1755

s‐25‐18‐4 12.2 9.1 170 0.0044 140 0.1748

s‐25‐18‐5 12.2 5.6 120 0.0047 170 0.1751

s‐25‐16‐1 12.2 3.5 135 0.0007 50 0.1601

s‐25‐16‐3 12.3 5.1 105 0.0039 110 0.1593

s‐25‐16‐4 12.2 3.5 180 0.0008 50 0.1361

21 
 

  

                 

                 

                 

             

           

Table 6. Data from Cable Material Tests 

NDIR FTIR 

Code Specimen 

Mass (g) 

Δm 

(g) 

Δt (s) 

Flaming 

FCO2 

(L/L) 

FCO 

(L/L) 

FO2 

(L/L) 

FCO 

(L/L) 

FHCl 

(L/L) 

c‐50‐21‐1 56.9 13.8 175 0.0041 340 0.2051 310 900

c‐50‐21‐2 38.2 9.5 169 0.0033 220 0.2051 220 810

c‐50‐21‐3 37.7 9.1 145 0.0033 240 0.2062 230 800

c‐50‐18‐1 35.7 8.7 180 0.0029 210 0.1779 210 750

c‐50‐18‐2 35.6 8.7 190 0.0028 220 0.1769 220 730

c‐50‐18‐3 36.0 8.9 175 0.0032 280 0.1764 250 820

c‐50‐16‐1 36.2 8.7 160 0.0029 230 0.1597 230 750

c‐50‐16‐2 35.0 7.8 135 0.0033 340 0.1562 300 880

c‐50‐16‐3 35.2 8.1 158 0.0030 230 0.1564 240 850

c2‐50‐21‐1 36.5 8.1 140 0.0048 330 0.2044 330 1220

c2‐50‐21‐2 37.3 8.2 140 0.0050 340 0.2042 320 1180

c2‐50‐21‐3 37.2 8.4 135 0.0052 370 0.2039 350 1190

c2‐50‐16‐1 37.2 8.8 180 0.0046 410 0.1554 350 1080

c2‐50‐16‐2 38.0 8.9 190 0.0044 350 0.1554 310 1100

c2‐50‐16‐3 37.5 8.7 175 0.0047 410 0.1546 340 1160

c2‐50‐14‐2 36.8 8.4 185 0.0041 380 0.1361 320 1370

c2‐50‐14‐3 38.7 9.6 240 0.0036 290 0.1335 290 1210

c2‐50‐14‐4 36.9 8.1 175 0.0039 360 0.1366 310 1240

c‐25‐21‐1 38.0 8.5 220 0.0028 160 0.2072

c‐25‐21‐2 37.4 8.3 230 0.0027 140 0.2075

c‐25‐21‐3 37.2 8.1 230 0.0026 130 0.2072

c‐25‐18‐1 36.0 7.2 230 0.0020 120 0.1789

c‐25‐18‐2 35.4 6.7 260 0.0020 120 0.1786

c‐25‐18‐3 35.7 6.8 250 0.0019 110 0.1775

c‐25‐16‐1 35.7 4.8 265 0.0014 80 0.1584

c‐25‐16‐2 36.4 4.2 260 0.0014 80 0.1586

c‐25‐16‐3 35.8 4.4 245 0.0015 80 0.1604

22 
Table 7. Gas Yields from Bookcase Material Tests 

Code Specimen 

Mass (g) 

Δm 

(g) 

yCO2 

(g/g) 

yCO 

(g/g) 

yHCN 

(g/g) 

yHCl 

(g/g) 

yNO 

(g/g) 

yNO2 

(g/g) 

b‐50‐21‐1 149.8 106.0 1.10 0.010

< 0.0084

< 0.0065

< 0.019

< 0.016

b‐50‐21‐2 135.6 105.2 1.11 0.010

< 0.0086

< 0.0066

< 0.019

< 0.017

< 

b‐50‐21‐3 138.4 103.7 1.13 0.009

< 0.0083

< 0.0064

< 0.018

< 0.016

< 

b‐50‐18‐1 136.0 103.8 1.09 0.013

< 0.0087

< 0.0067

< 0.019

< 0.017

< 

b‐50‐18‐2 137.4 101.5 1.10 0.012

< 0.0084

< 0.0065

< 0.019

< 0.016

< 

b‐50‐18‐3 138.1 102.1 1.10 0.013

< 0.0087

< 0.0067

< 0.019

< 0.017

< 

b‐50‐16‐1 119.2 98.4 1.02 0.020

< 0.0079

< 0.0061

< 0.018

< 0.015

< 

b‐50‐16‐2 136.6 101.7 1.05 0.020

< 0.0086

< 0.0066

< 0.019

< 0.017

< 

b‐50‐16‐3 120.6 91.6 1.10 0.018

< 0.0080

< 0.0062

< 0.018

< 0.016

< 

b2‐50‐21‐1 131.5 99.6 1.02 0.006

< 0.0045

< 0.0035

< 0.010

< 0.009

< 

b2‐50‐21‐2 130.2 97.3 1.01 0.006

< 0.0042

< 0.0032

< 0.009

< 0.008

< 

b2‐50‐21‐3 127.4 96.9 1.03 0.006

< 0.0043

< 0.0033

< 0.010

< 0.008

b2‐50‐16‐1 131.6 99.7 1.03 0.010

< 0.0048

< 0.0037

< 0.011

< 0.009

b2‐50‐16‐2 128.2 97.3 1.02 0.008

< 0.0045

< 0.0035

< 0.010

< 0.009

b2‐50‐16‐3 123.8 93.8 1.03 0.009

< 0.0048

< 0.0037

< 0.011

< 0.009

b2‐50‐14‐1 129.7 95.7 0.69 0.058

< 0.0051

< 0.0039

< 0.011

< 0.010

b2‐50‐14‐2 132.2 98.1 0.93 0.032

< 0.0048

< 0.0037

< 0.011

< 0.009

b2‐50‐14‐3 131.6 98.2 0.93 0.032

< 0.0049

< 0.0038

< 0.011

< 0.010

b‐25‐21‐1 124.6 93.3 1.15 0.015b‐25‐21‐3 128.6 103.0 1.12 0.020b‐25‐21‐4 138.8 102.5 1.14 0.022b‐25‐18‐1 126.6 34.6 0.85 0.028b‐25‐18‐2 127.4 30.3 0.92 0.023b‐25‐18‐3 130.9 54.5 0.55 0.018b‐25‐18‐4 122.5 32.2 0.92 0.022b‐25‐16‐1 128.4 26.9 0.61 0.037b‐25‐16‐2 129.6 21.9 0.84 0.027b‐25‐16‐3 128.6 25.8 0.86 0.027
Table 8. Gas Yields from Sofa Material Tests 

Code Specimen 

Mass (g) 

Δm 

(g) 

yCO2 

(g/g) 

yCO 

(g/g) 

yHCN 

(g/g) 

yHCl 

(g/g) 

yNO 

(g/g) 

yNO2 

(g/g) 

s‐50‐21‐1 12.0 8.5 1.39 0.026 0.0033 < 0.0055 < 0.016 < 0.014 

s‐50‐21‐2 11.8 8.5 1.39 0.027 0.0045 < 0.0051 < 0.015 < 0.013 

s‐50‐21‐3 11.7 8.7 1.45 0.027 0.0032 < 0.0054 < 0.016 < 0.014 

s‐50‐18‐1 12.4 8.6 1.43 0.034 0.0071 < 0.0058 < 0.017 < 0.015 

s‐50‐18‐2 11.8 8.5 1.48 0.036 0.0071 < 0.0054 < 0.016 < 0.014 

s‐50‐18‐3 11.9 8.6 1.45 0.036 0.0088 < 0.0054 < 0.016 < 0.014 

s‐50‐16‐1 12.2 8.7 1.38 0.045 0.0124 < 0.0056 < 0.016 < 0.014 

s‐50‐16‐2 12.1 8.4 1.44 0.044 0.0120 < 0.0059 < 0.017 < 0.015 

s‐50‐16‐3 12.3 9.0 1.41 0.044 0.0132 < 0.0060 < 0.017 < 0.015 

s2‐50‐21‐1 11.5 8.5 1.34 0.024 0.0035 < 0.0025 < 0.007 < 0.006 

s2‐50‐21‐2 11.8 8.7 1.40 0.024 0.0036 < 0.0029 < 0.008 < 0.007 

s2‐50‐21‐3 11.8 8.7 1.34 0.025 0.0038 < 0.0027 < 0.008 < 0.007 

s2‐50‐16‐1 10.6 7.7 1.31 0.032 0.0059 < 0.0033 < 0.010 < 0.008 

s2‐50‐16‐2 11.7 8.6 1.42 0.036 0.0114 < 0.0032 < 0.009 < 0.008 

s2‐50‐16‐3 11.7 8.6 1.40 0.037 0.0114 < 0.0030 < 0.009 < 0.008 

s2‐50‐14‐1 11.2 8.0 1.38 0.033 0.0022 < 0.0036 < 0.010 < 0.009 

s2‐50‐14‐2 11.7 8.5 1.41 0.032 0.0041 < 0.0030 < 0.009 < 0.008 

s2‐50‐14‐3 11.9 8.5 1.38 0.034 0.0054 < 0.0032 < 0.009 < 0.008 

s‐25‐21‐1 12.4 8.5 1.56 0.024s‐25‐21‐2 12.1 6.4 1.45 0.024s‐25‐21‐3 12.2 8.1 1.63 0.024s‐25‐18‐1 12.2 5.3 0.91 0.030s‐25‐18‐2 12.2 5.5 1.06 0.028s‐25‐18‐3 12.3 5.0 1.32 0.028s‐25‐18‐4 12.2 9.1 1.42 0.024s‐25‐18‐5 12.2 5.6 1.94 0.037s‐25‐16‐1 12.2 3.5 0.15 0.022s‐25‐16‐3 12.3 5.1 1.36 0.029s‐25‐16‐4 12.2 3.5 0.16 0.030
Table 9. Gas Yields from Cable Material Tests 

Code Specimen 

Mass (g) 

Δm 

(g) 

yCO2 

(g/g) 

yCO 

(g/g) 

yHCN 

(g/g) 

yHCl 

(g/g) 

yNO 

(g/g) 

yNO2 

(g/g) 

c‐50‐21‐1 56.9 13.8 0.94 0.056 < 0.011 0.23 < 0.024 < 0.021 

c‐50‐21‐2 38.2 9.5 1.12 0.051 < 0.016 0.22 < 0.036 < 0.031 

c‐50‐21‐3 37.7 9.1 1.06 0.055 < 0.014 0.24 < 0.031 < 0.027 

c‐50‐18‐1 35.7 8.7 1.16 0.066 < 0.016 0.26 < 0.036 < 0.031 

c‐50‐18‐2 35.6 8.7 1.21 0.065 < 0.017 0.26 < 0.038 < 0.033 

c‐50‐18‐3 36.0 8.9 1.14 0.071 < 0.016 0.25 < 0.036 < 0.031 

c‐50‐16‐1 36.2 8.7 1.02 0.063 < 0.017 0.29 < 0.038 < 0.033 

c‐50‐16‐2 35.0 7.8 1.15 0.078 < 0.015 0.30 < 0.033 < 0.029 

c‐50‐16‐3 35.2 8.1 1.16 0.073 < 0.020 0.32 < 0.044 < 0.039 

c2‐50‐21‐1 36.5 8.1 1.03 0.049 < 0.007 0.22 < 0.016 < 0.014 

c2‐50‐21‐2 37.3 8.2 1.04 0.049 < 0.007 0.23 < 0.016 < 0.014 

c2‐50‐21‐3 37.2 8.4 0.99 0.051 < 0.007 0.21 < 0.016 < 0.014 

c2‐50‐16‐1 37.2 8.8 0.99 0.062 < 0.008 0.23 < 0.018 < 0.016 

c2‐50‐16‐2 38.0 8.9 1.03 0.059 < 0.009 0.24 < 0.020 < 0.018 

c2‐50‐16‐3 37.5 8.7 1.04 0.061 < 0.008 0.23 < 0.018 < 0.016 

c2‐50‐14‐4 36.8 8.4 0.91 0.057 < 0.009 0.28 < 0.020 < 0.018 

c2‐50‐14‐2 38.7 9.6 0.82 0.048 < 0.009 0.28 < 0.020 < 0.018 

c2‐50‐14‐3 36.9 8.1 0.91 0.057 < 0.009 0.29 < 0.020 < 0.018 

c‐25‐21‐1 38.0 8.5 1.08 0.050

c‐25‐21‐2 37.4 8.3 1.09 0.050

c‐25‐21‐3 37.2 8.1 1.21 0.051

c‐25‐18‐1 36.0 7.2 1.25 0.059

c‐25‐18‐2 35.4 6.7 1.33 0.068

c‐25‐18‐3 35.7 6.8 1.25 0.062

c‐25‐16‐1 35.7 4.8 0.65 0.039

c‐25‐16‐2 36.4 4.2 0.66 0.043

c‐25‐16‐3 35.8 4.4 0.72 0.043
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B. CALCULATIONS OF TOXIC GAS YIELDS WITH UNCERTAINTIES 

Table 10 contains the yields of the combustion products calculated using the data from Table 7 

Table 8, and Table 9. 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 10. Yields of Combustion Products from Cone Calorimeter Tests. 

Gas 

Heat Flux 

(kW/m2) 

Flow 

Rate 

(L/s) 

Initial 

O2 % Bookcase Sofa Cable 

CO2

50 25 21 

18 

16 

1.11 ± 1.5% 

1.10 ± 0.1% 

1.06 ± 3.5% 

1.41 ±

1.46 ± 

1.41 ± 

 2.2% 

1.8% 

2.3% 

1.04 ± 8.5% 

1.17 ± 3.0% 

1.11 ± 6.8% 

50 12.5 21 

16 

14 

1.02 ± 1.1% 

1.03 ± 0.5% 

0.93 ± 0.3% 

1.36 ±

1.38 ± 

1.39 ± 

 2.6% 

4.4% 

1.3% 

1.02 ± 2.5% 

1.02 ± 2.6% 

0.88 ± 5.9% 

25 25 21 

18 

16 

1.14 ± 1.2% 

0.89 ± 4.4% 

0.85 ± 1.4% 

1.55 ±

1.33 ± 

1.36 ± 

 6.1% 

30% 

51% 

1.13 ± 6.4% 

1.28 ± 3.7% 

0.68 ± 5.7% 

CO 

50 25 21 

18 

16 

0.010 ± 7.7% 

0.013 ± 2.9% 

0.019 ± 7.4% 

0.027 ± 

0.035 ± 

0.044 ± 

1.9% 

4.2% 

1.4% 

0.054 ± 4.8% 

0.067 ± 4.3% 

0.071 ± 11% 

50 12.5 21 

16 

14 

0.006 ± 2.6% 

0.009 ± 9.1% 

0.032 ± 0.8% 

0.024 ± 

0.035 ± 

0.033 ± 

0.9% 

7.3% 

3.6% 

0.050 ± 2.6% 

0.061 ± 3.0% 

0.054 ± 9.9% 

25 25 21 

18 

16 

0.019 ± 20% 

0.023 ± 17% 

0.027 ± 0.9% 

0.024 ± 

0.029 ± 

0.029 ± 

0.5% 

16% 

15% 

0.051 ± 1.2% 

0.063 ± 7.0% 

0.042 ± 6.2% 

HCN 

50 25 21 

18 

16 

< 0.0084 

< 0.0086 

< 0.0082 

0.0037 ± 

0.0077 ± 

0.0125 ± 

29% 

23% 

15% 

< 0.014 

< 0.016 

< 0.017 

50 12.5 21 

16 

14 

< 0.0043 

< 0.0047 

< 0.0049 

0.0036 ± 

0.0096 ± 

0.0039 ± 

15% 

43% 

50% 

< 0.0070 

< 0.0083 

< 0.0090 

HCl 

50 25 21 

18 

16 

< 0.0065 

< 0.0066 

< 0.0063 

< 

< 

< 

0.0053 

0.0055 

0.0058 

0.23 ± 14% 

0.26 ± 12% 

0.30 ± 15% 

50 12.5 21 

16 

14 

< 0.0033 

< 0.0036 

< 0.0038 

< 

< 

< 

0.0027 

0.0032 

0.0033 

0.22 ± 15% 

0.23 ± 14% 

0.28 ± 12% 

NO 

50 25 21 

18 

16 

< 0.019 

< 0.019 

< 0.018 

< 

< 

< 

0.015 

0.016 

0.017 

< 0.030 

< 0.036 

< 0.038 

50 12.5 21 

16 

14 

< 0.010 

< 0.010 

< 0.011 

< 

< 

< 

0.0078 

0.0091 

0.0094 

< 0.016 

< 0.019 

< 0.020 

26 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Gas 

Heat Flux 

(kW/m2) 

Flow 

Rate 

(L/s) 

Initial 

O2 % Bookcase Sofa Cable 

NO2 

50 25 21 

18 

16 

< 0.016 

< 0.017 

< 0.016 

< 0.013 

< 0.014 

< 0.015 

< 0.027 

< 0.032 

< 0.034 

50 12.5 21 

16 

14 

< 0.0084 

< 0.0092 

< 0.010 

< 0.0068 

< 0.0080 

< 0.0082 

< 0.014 

< 0.016 

< 0.018 

Acrolein 

50 25 21 

18 

16 

< 0.010 

< 0.010 

< 0.010 

< 0.0082 

< 0.0085 

< 0.0090 

< 0.016 

< 0.019 

< 0.021 

50 12.5 21 

16 

14 

< 0.0051 

< 0.0056 

< 0.0058 

< 0.0042 

< 0.0049 

< 0.0050 

< 0.0083 

< 0.010 

< 0.011 

Formaldehyd 

e 

50 25 21 

18 

16 

< 0.011 

< 0.011 

< 0.010 

< 0.0088 

< 0.0091 

< 0.010 

< 0.017 

< 0.021 

< 0.022 

50 12.5 21 

16 

14 

< 0.0055 

< 0.0060 

< 0.0063 

< 0.0044 

< 0.0052 

< 0.0054 

< 0.0089 

< 0.011 

< 0.011 

27 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The values in Table 11 are the values from Table 10 divided by the notional yields from Table 3. 

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

Table 11. Fractions of Notional Yields. 

Gas 

Heat 

Flux 

(kW/m2

) 

Flow 

Rate 

(L/s) 

Initial 

O2 % Bookcase Sofa Cable 

CO2

50 25 21 

18 

16 

0.65 ± 2.5% 

0.64 ± 1.1% 

0.62 ± 4.5% 

0.72

0.75

0.72

 ±

 ±

 ±

 3.2% 

 2.8% 

 3.3% 

0.49 ± 9.5% 

0.55 ± 4.0% 

0.53 ± 7.8% 

50 12.5 21 

16 

14 

0.59 ± 1.9% 

0.60 ± 0.8% 

0.54 ± 0.5% 

0.70

0.71

0.71

 ±

 ±

 ±

 3.6% 

 5.4% 

 2.3% 

0.48 ± 3.5% 

0.48 ± 3.6% 

0.42 ± 6.9% 

25 25 21 

18 

16 

0.66 ± 2.1% 

0.52 ± 7.5% 

0.50 ± 2.4% 

0.79

0.68

0.70

 ±

 ±

 ±

 7.1% 

 31% 

 52% 

0.53 ± 7.4% 

0.61 ± 4.7% 

0.32 ± 6.7% 

CO 

50 25 21 

18 

16 

0.009 ± 8.7% 

0.012 ± 8.7% 

0.018 ± 8.7% 

0.022 

0.028 

0.036 

± 

± 

± 

5.9% 

8.2% 

5.4% 

0.041 ± 5.8% 

0.051 ± 5.3% 

0.054 ± 12% 

50 12.5 21 

16 

14 

0.006 ± 8.7% 

0.008 ± 8.7% 

0.029 ± 8.7% 

0.020 

0.028 

0.027 

± 

± 

± 

4.9% 

11% 

7.6% 

0.037 ± 3.6% 

0.046 ± 4.0% 

0.040 ± 11% 

25 25 21 

18 

16 

0.017 ± 8.7% 

0.021 ± 8.7% 

0.025 ± 8.7% 

0.020 

0.023 

0.024 

± 

± 

± 

4.5% 

20% 

19% 

0.038 ± 2.2% 

0.047 ± 8.0% 

0.031 ± 7.2% 

HCN 

50 25 21 

18 

16 

< 0.15 

< 0.15 

< 0.14 

0.019

0.040 

0.065 

±

± 

± 

 33% 

27% 

19% 

< 0.34 

< 0.41 

< 0.43 

50 12.5 21 

16 

14 

< 0.076 

< 0.082 

< 0.087 

0.019 

0.050 

0.020 

± 

± 

± 

19% 

47% 

54% 

< 0.18 

< 0.21 

< 0.23 

HCl 

50 25 21 

18 

16 

< 2.5 

< 2.6 

< 2.4 

< 

< 

< 

0.77 

0.80 

0.85 

0.69 ± 14% 

0.78 ± 13% 

0.91 ± 16% 

50 12.5 21 

16 

14 

< 1.3 

< 1.4 

< 1.5 

< 

< 

< 

0.39 

0.46 

0.47 

0.67 ± 15% 

0.71 ± 14% 

0.86 ± 12% 

28 
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 135719

 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 

Changing the oxygen concentration had little effect on CO2 yields. In some cases at the lowest 

oxygen concentrations there was a measurable reduction. In the case of the sofa materials, at the 

lower heat flux, reducing the oxygen concentration increased the variability in the CO2 yield 

considerably. This was the result of the combined effect of low heat flux and low oxygen failing 

to sustain combustion of the specimen, resulting in some degree of non-flaming pyrolysis in 

which the specimen mass failed to oxidize to either CO or CO2, but instead escaped as unreacted 

hydrocarbon (which we did not measure). 

On the other hand, CO yields at 50 kW/m2

 and 25 L/s were affected by altering the available 

oxygen. As can be seen in Figure 4 to Figure 6, decreasing the available oxygen to 16 % 

increased the CO yields—about a twofold increase for the bookcase, a 60 % increase for the 

sofa, and a 30 % increase for the cable. When the oxygen volume percent was lower than 16 %, 

this resulted in a very large increase in the CO yield, a factor of 4 for the bookcase, or a slight 

decrease (less than 10 %) from the maximum yield at 16 % oxygen, for the sofa and cable. 

It can also be seen in these figures that reducing the air flow to 12.5 L/s resulted in consistently 

lower CO yields. There are several possible explanations: for example, the lower flow may have 

increased the effluent residence time near the hot cone, allowing more time to oxidize, or the 

slower flow may have allowed more steady combustion, whereas a more fluctuating flow at the 

higher flow has the potential to choke off and quench pockets that have not fully oxidized. 

29 
   

   

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

COYield (g/g)

10 12 14 16 18 20 22

O2 % by Volume

Figure 4. Effect of Oxygen Concentration on CO Yields, Bookcase (dashed line = 

reduced flow). Error bars are ± the standard deviation of yields from multiple 

runs. 

0.05

0.04

COYield (g/g)

10 12 14 16 18 20 22
 

0.03

0.02

0.01

0

O2 % by Volume

Figure 5. Effect of Oxygen Concentration on CO Yields, Sofa (dashed line = 

reduced flow). Error bars are ± the standard deviation of yields from multiple 

runs. 

30 
   

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

COYield (g/g)

10 12 14 16 18 20 22

O2 % by Volume

Figure 6: Effect of Oxygen Concentration on CO Yields, Cable (dashed line = 

reduced flow). Error bars are ± the standard deviation of yields from multiple 

runs. 

2. HCl and HCN 

HCN was detected via FTIR and was only observed in the sofa material tests. Figure 7 shows 

the calculated volume fraction from the FTIR spectra for each of 3 experiments, all conducted at 

50 kW/m2

, 12.5 L/s flow, and 16 % oxygen by volume. The three superimposed plots have been 

time shifted so that the time of ignition is normalized. One of the runs (circles) ultimately 

resulted in a calculated yield roughly half of the other two, resulting in a large variability of 33 % 

(see Table 10). If this run is discarded, then the reported yield of HCN at this condition should 

be 0.0114 with an uncertainty of 0.2%. 

It is also worth noting that the total time for combustion extended to about 120 s on the scale in 

Figure 7. Other combustion products continue to be observed in this time period. In other 

words, the bulk of the HCN is produced early in the combustion process. 

Figure 8 shows the results, as yields, for the generation of HCN at different oxygen volume 

fractions. As with the CO, there is linear increase in HCN yields as the oxygen volume fraction 

decreases from 0.21 to 0.16, but at the lowest oxygen volume fraction the yield of HCN is quite 

low. Another important consideration for Figure 8 is that if the outlier run is excluded, then the 

results from the 12.5 L/s experiments are much closer to the 25 L/s ones, although still slightly 

lower. The outlier was included because we feel it is representative of the variability of this 

measurement. 

31 
   

   

0

50

100

150

200

250

300

350

400

450

500

30 50 70 90 110 130 150

HCNVolume Fraction (L/L)

Test Time (sec)

Figure 7. HCN Volume Fractions, Sofa, 50 kW/m2, 12.5 L/s, 16 % O2 by Volume. 

Uncertainty is 10 % of the Reported HCN Volume Fraction 

0.014

0.012

HCN Yield (g/g)0.010

0.008

0.006

0.004

0.002

0.000

O2 % by Volume

10 12 14 16 18 20 22

Figure 8. Effect of Oxygen Concentration on HCN Yields, Sofa. Error bars are ± 

the standard deviation of yields from multiple runs 

32 
   

HCl was detected via FTIR and was only observed in the cable tests. Figure 9 shows the 

calculated volume fraction from the FTIR spectra for each of 3 experiments, all conducted at 

50 kW/m2, 12.5 L/s flow and 16 % oxygen by volume. The three superimposed plots have been 

time shifted so that the time of ignition is normalized. The 3 runs are quite consistent, and 

numerically have a variability in yield of 3.8 %. This is despite the fact that there is some 

variability in the timing of the release of HCl, lasting approximately 20 s longer for one of the 

experiments (diamonds in the figure). In other words, the measured volume fraction at any one 

time is more variable than the integrated quantity. 

0

200

400

600

800

1000

1200

1400

30 80 130 180 230 280

HCl Volume Fraction (L/L)

Test Time (sec)

Figure 9. HCl Volume Fractions, Cable, 50 kW/m2

, 12.5 L/s, 16 % O2 by Volume. 

Uncertainty is 10 % of the Reported Volume Fraction. 

Figure 10 shows the effect of oxygen concentration on the yields of HCl from the cable 

materials. The yields are somewhat higher at lower oxygen concentrations, but this may be 

accounted for by a slightly lower total mass lost—if disproportionately more of the carbon 

remains in the char. At the lowest oxygen volume fraction, 0.14, the yield of HCl increases by 

about 20 %. 

33 
   

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

10 12 14 16 18 20 22

HCl Yield (g/g)

O2 % by Volume

Figure 10. Effect of Oxygen Concentration on Yields of HCl, Cables. Error bars are 

± the standard deviation of yields from multiple runs 

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. In these experiments, the sofa material came out 

best, achieving over 70 % of the notional yield. The bookcase fared slightly worse, achieving 

only 65 % of the notional yield for CO2, and the cable had the lowest at around half. The 

relatively lower yields of CO2 from the cables is an expected result of flame inhibition due to the 

chlorine. These trends are consistent with our qualitative observation of, for example, the 

thickness of the smoke produced. 

The yields of CO from all the specimens ranged from about 0.01 to 0.06, which corresponds to 

1 % to 5 % of the notional values. These values are consistent with relatively fuel-lean 

combustion34 and are an order of magnitude lower than the CO yields expected of postflashover 

fires.14 

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 or wall loss in the duct or 

sampling line. 

The detection limited yields of HCl from the sofa specimens was 80 % of the notional yield at 

the higher flow rate, and 40% of the notional yield at the lower flow rate. The detection limited 

yield of HCl from the bookcase was 2.5 and 1.5 times the notional yield, for the high and low 

flows respectively. Chlorine is present at well under one percent by mass in these two products. 

Such small quantities are not capable of producing toxicologically significant yields of HCl, 

suggesting that they can be either ruled out by elemental analysis as unimportant, or that limits of 

detection are not a barrier to measuring significant quantities of HCl in this apparatus. 

34 
Yields of HCN from the sofa are between 2 % and 6 % of their notional values. The highest 

relative yield is found at 16 % oxygen by volume. Despite the lower oxygen, these flames 

appear relatively fuel-lean, and the nitrogen may appear as molecular nitrogen or nitrogen 

dioxides. 

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. 

	 In this work we used a longer path length cell than in previous work. However, the 

increased sensitivity was offset by the instantaneous nature of the measurements (as 

opposed to averaging over dozens of data points) and the fact that the gases did not 

accumulate as they do in the closed chamber tests such as NFPA 269 and NFPA 270 

(toxicity test method and smoke density chamber respectively). The CO concentrations 

measured here are approximately one-tenth of those measured in the closed-chamber 

apparatus. However, non-linear effects resulted in a 25 % deficit compared to the NDIR 

measurements of CO at the highest concentrations. 

	 The cell volume remained small and provided good time resolution. For example, the 

measured HCl concentrations go from zero to the maximum in two data intervals (see 

Figure 9). 

	 The lack of a filter did not adversely affect the measurements. Compared to previous 

work with other apparatus, the smoke measured here was relatively dilute. The cell only 

required cleaning a few times over the course of all of the experiments reported here. 

The internal mirrors were easily cleaned with ethanol and deionized water. The KBr 

windows were replaced once. 

	 A heated sample line (as recommended in the SAFIR report35 and ISO 1970236) enabled 

near-quantitative collection of HCl, a compound that is generally regarded as difficult to 

determine. 

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, 

35 
 

 

 

 

 

 

 

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 2. 

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: 

 CO  2 exp   , t 2 t 2 2.36 5       CO HCN FED    t  6 t t1 35000 t1 1.2 10  

where Δt is the exposure interval in minutes. 

The FEC of the four irritant gases were estimated from their volume fractions and the 

incapacitating levels in ISO 13571 (FHCl, etc.). The results are compiled in Table 12. 

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 NO acrolein formaldehyde 

  

2 2 

    FCi

Table 12. Limits of importance of undetected toxins 

Volume fraction (μL/L) FEC Contribution 

HCl NO2 C3H4O H2CO HCl NO2 C3H4O H2CO 

Incapacitating 

Level 1000 250 30 250 

Bookcase < 20 < 40 < 20 < 40 < 0.02 < 0.16 < 0.66 < 0.16 

Sofa < 20 < 40 < 20 < 40 < 0.02 < 0.16 < 0.66 < 0.16 

Cable 1370 < 40 < 20 < 40 0.58 < 0.07 < 0.28 < 0.07

 to 730 < 40 < 20 < 40 0.43 < 0.09 < 0.39 < 0.09 

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.37 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. If we increase the incapacitating level of acrolein to 250 μL/L, 

the relative contribution to FEC become those in Table 13. In this case the relative importance 

of acrolein falls below 0.1 when other irritants are detected. 

36 
 

 

 

 

 

 

 

Table 13. Limits of Importance of Undetected Toxicants 

Volume fraction (μL/L) FEC Contribution 

HCl NO2 C3H4O H2CO HCl NO2 C3H4O H2CO 

Incapacitating 

Level 1000 250 250 250 

Bookcase < 20 < 40 < 20 < 40 < 0.05 < 0.38 < 0.19 < 0.38 

Sofa < 20 < 40 < 20 < 40 < 0.05 < 0.38 < 0.19 < 0.38 

Cable 1370 < 40 < 20 < 40 0.77 < 0.09 < 0.05 < 0.09 

to 730 < 40 < 20 < 40 0.65 < 0.14 < 0.07 < 0.14 

Where specimens like the bookcase and sofa produce narcotic gases, CO and HCN, and irritants 

are below the limits of detection, the narcotic gases are the primary contributors to 

incapacitation. Assuming that the irritant gases are present in just under the limits of detection, 

in order for them to reach an incapacitating concentration, the relative concentration of CO 

would be incapacitating in a few minutes; the relative concentration of HCN would be 

incapacitating in under a minute. 

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38 
 

VI. CONCLUSIONS 

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 

cone calorimeter from ISO 5660-1 / ASTM E 1354. 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 added an enclosure and a gas supply capable of reduced 

oxygen, in order to better approximate conditions in an underventilated fire. 

For the standard test procedure: 

	 The CO2 yields were very repeatable and represented between half and 80 % of the 

carbon in the specimens. All specimens left a black residue that continued to pyrolyze 

after the flaming halted. These residues were presumably carbon-enriched, accounting 

for the yields being below the notional yields. 

	 The CO yields were also very repeatable, with the exception of the bookcase at low heat 

flux and the higher oxygen concentrations. 

	 The HCN yields were below the limit of detection for the bookcase and cable specimens. 

The HCN yields from the sofa were 3 to 10 times the limit of detection and had a 

variation in repeatability between 5 % and 40 % of the reported yield depending on the 

test conditions. 

	 The HCl yields were below the limit of detection for the bookcase and sofa specimens. 

For the cables they were well above the limit of detection and accounted for 70 % of the 

Cl in the specimens. 

	 None of the other irritant gases appeared in concentrations above their limits of detection. 

Regarding the variation in test conditions, we conclude: 

	 An incident heat flux of 25 kW/m2

 does not provide any information beyond that which 

is found at 50 kW/m2 . In fact it leads to increased variability from test to test because of 

slow ignition or early extinction. 

	 The trend of toxic gas yields increasing with decreasing initial oxygen concentration 

holds uniformly across gases and specimen types over the oxygen volume fraction range 

of 0.21 to 0.16. When the oxygen volume fraction is 0.14, the results are unpredictable 

for both gases and items burned. Therefore, we don’t recommend testing at this level? 

With the exception of CO from the bookcase, the majority of the CO yields were lower at 

0.14 than at 0.16. 

	 Reducing the total flow to 12.5 L/s reduces the limit of detection of the gases by a factor 

of two, and allows the achievement of lower oxygen concentrations. However, yields 

measured at the lower flow were consistently lower than at the higher flow. 

Calculation of the contributions of the gases to incapacitation of people who might be exposed to 

these environments showed: 

	 Incapacitation from the bookcase material effluent would be primarily from CO. 

39 
 Incapacitation from the sofa material effluent would be from a combination of CO and 

HCN. 

 Incapacitation from the cable effluent would be initially from HCl; the related yield of 

CO would become incapacitating after approximately15 minutes. 

If the CO yield were at the expected postflashover value of 0.2, 

 Incapacitation from the bookcase material effluent would be primarily from CO. 

 Incapacitation from the sofa material effluent would be primarily from CO. 

 Incapacitation from the cable material effluent would be initially from HCl; a 0.2 yield of 

CO would become incapacitating after a few minutes. 

VII. ACKNOWLEDGEMENTS 

The authors express their appreciation to Randy Shields for his assistance in performing the tests. 

40 
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”, 

NIST Special Publication 1086, National Institute of Standards and Technology, 

Gaithersburg, MD, 187 pages (2008). 

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. “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. 

7. See, e.g., “Standard for the Flammability (Open Flame) of Mattress Sets,” 16 CFR Part 1633, 

Federal Register 70 (50), 13471-13523, 2006. 

8.http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_tc_browse.htm?commid=50540& 

published=on&development=on. 

9. “Life-threatening Components of Fire – Guidelines for the Estimation of Time to 

Compromised Tenability in Fires,” ISO 13571, International Standards Organization, Geneva, 

2012. 

10. "Guidelines for Assessing the Fire Threat to People," ISO 19706, International Standards 

Organization, Geneva, 2011. 

11. 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). 

12. "Guidance for Comparison of Toxic Gas Data between Different Physical Fire Models and 

Scales," ISO 29903, International Standards Organization, Geneva, 2012. 

13. “Standard Test Method for Developing Toxic Potency Data for Use in Fire Hazard 

Modeling,” NFPA 269, NFPA International, Quincy, MA, 2012. 

14. “Standard Test Method for Measuring Smoke Toxicity for Use in Fire Hazard Analysis,” 

ASTM E1678-10, ASTM International, West Conshohocken, PA, 2010. 

15. (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 

Component Yields from Room-scale Fire Tests,” Fire and Materials 34, 285-314, (2010), 

DOI: 10.1002/fam.1024. 

41 
16. 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. 

17. Gann, R.G., Marsh, N.D., Averill, J.A., and Nyden, M.R., “Smoke Component Yields from 

Bench-scale Fire Tests: 1. NFPA 269/ASTM E 1678,” NIST Technical Note 1760, National 

Institute of Standards and Technology, Gaithersburg, MD, 57 pages, (2013). 

18. Kaplan, H.L., Grand, A.F., and Hartzell, G.E., Combustion Toxicology: Principles and Test 

Methods, Technology Publishing Co., Lancaster, PA, 1983. 

19. "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. 

20. "Controlled Equivalence Ratio Method for the Determination of the Hazardous Components 

of Fire Effluent," ISO/TS 19700, International Standards Organization, 2010. 

21. "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. 

22. "Plastics — Smoke Generation — Part 2: Determination of Optical Density by a Singlechamber Test, ISO 5659-2, International standards Organization, Geneva, 1994. 

23. Marsh, N.D., Gann, R.G., and Nyden, M.R., “Smoke Component Yields from Bench-scale 

Fire Tests: 2. ISO 19700 Controlled Equivalence Ratio Tube Furnace” NIST Technical Note 

1761, National Institute of Standards and Technology, Gaithersburg, MD, 45 pages (2013). 

24. Marsh, N.D., Gann, R.G., and Nyden, M.R., “Observations on the Generation of Toxic 

Products in the NFPA/ISO Smoke Density Chamber,” Proceedings of the 12th International 

Conference on Fire Science & Engineering, (Interflam 2010), Nottingham UK, (2010). 

25. Mulholland, G., Janssens, M., Yusa, S., Twilley, W., and Babrauskas, V.”The effect of 

oxygen concentration on CO and Smoke Produced by Flames,” Proceedings of the Third 

International Symposium on Fire Safety Science, Edinburgh UK, pp. 585-594, (1991). 

doi:10.3801/IAFSS.FSS.3-585 

26. Babrauskas, V., Twilley, W.H., Janssens, M., and Yusa, S., “A cone calorimeter for 

controlled-atmosphere studies.” Fire and Materials 16, 37-43, (1992). 

27. Hshieh, F.Y., Motto, S.E., Hirsch, D.B., and Beeson, H.D., “Flammability Testing Using a 

Controlled-atmosphere Cone Calorimeter,” Proceedings of the 18th International Conference 

on Fire Safety Science, Millbrae CA, p. 999 (1993). 

28. Gomez, C., Janssens, M., and Zalkin, A. “Using the Cone Calorimeter for Quantifying Toxic 

Potency” Proceedings of the 12th International Fire Science & Engineering Conference 

(Interflam 10), Nottingham UK, (2010). 

42 
29. Gomez, C., Janssens, M., and Zalkin, A., “Measuring the Yields of Toxic Gases from 

Materials during Different Stages of Fire Development” In Fire and Materials 12 

international conference San Francisco, CA (2011). 

30. Guillaume, E., Marquis, D.M., and Chivas-Joly, C., “Usage of Controlled-atmosphere Cone 

Calorimeter to Provide Input Data for Toxicity Modeling,” in Fire and Materials, 12 

International Conference, San Francisco, CA (2011). 

31. 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 

32. Gas Phase Infrared Spectral Standards, Revision B, Midac Corp.; Irvine, CA (1999). 

33. Speitel, L.C., “Fourier Transform Infrared Analysis of Combustion Gases,” Federal Aviation 

Administration Report DOT/FAA/AR-01/88, 2001. 

34. 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). 

35. "Smoke Gas Analysis by Fourier Transform Infrared Analysis,: The SAFIR Project," VTT 

Research Note, Technical Research Centre of Finland, 81 Pages, 1999. 

36. “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. 

37. 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). 

43