Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient's Catalog NO. 

DoT/FAA/AM-86/3 

4. Title and Subtttle 5. Report Date 

INHALATION TOXICOLOGY: VI. EVALUATION OF THE RELATIVE 

NINE AIRCRAFT PANEL MAERIALS 

ROXICITY OF THERMAL DECOMPOSITION PRODUCTS FROM 

February 1986 

6. Performing Organizotton Code 

8. Performing Organization Report NO. 

7. Author's) C.R. Crane, D.C. Sanders, 

RJ- En-tt -tt DoT/FAA/AM-86/3 

9. Performing Organization Name and Address 10. Work Unat No. (TRAIS) 

Federal Aviation Administrat ion 

Civil Aercmedical Institute 11. Contract or Grant No. 

Oklahcpna City, Oklahcpna 73125 

13. Type of Report and Perbod Covered 

12. Sponsoring Agency Name and Address i 

Office of Aviation Medicine 

Federal Aviation Administration 

800 Independence Avenue, S.W. 

Washington, D.C. 20591 

14. Sponsoring Agency Code 

15. Supplementary Notes 

16. Abstroct 

The purpose of this study was to determine the relative toxicity of the 

combustion products from nine aircraft cabin panels, representing both composite 

and homogeneous construction, that rere being tested concurrently for 

flmbility and smoke production at the FAA Technical Center. We designed 

and constructed a cchnbustion/exposure assembly in which panel sections were 

pyrolyzed by radiant head directed onto the upper surface only; the relative 

toxicity of the evolved gases was n-easured by determining the effect (timeto-incapacitation) on the laboratory rat. We also determined the relative 

toxicity of gases from the same nine panels when pyrolyzed in the older 

(and smaller) combustion tube assembly in order to canpare the effects of 

the different pyrolysis modes. 

17. Key Words Combustion Toxicity 18. Distribution Statement 

Time-to-incapacitation (ti) 

Time-to death (td) 

Heat flux level 

Document is available to the public 

Internal Aircraft Panel Virginia 22161 

Information Service, Springfield, Pyrolysis condition 

through the National Technical 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

Unclassified Unclassified 15 

Form DOT F 1700.7 (8-72) Reproduction of completed pogc outhorizcd 

INHALATION TOXICOLOGY: VI. EVALUATION OF THE RELATIVE 

TOXICITY OF THEKMAL DECOMPOSIT ION PRODUCTS FROM 

AIRCRAFT PANEL MATERIALS 

INTROD UCT ION 

Modern aircraft interior panels have proven remarkably resistant to small 

ignition sources; indeed, all are required by Federal Aviation Regulation 

(FAR) 25.853(a) to be self-extinguishing when the ignition source is 

removed (1). They are self-extinguishing because more heat is required to 

evolve sufficient flammable gases than the burning material can provide 

without an external source of heat. Panels can and do burn, however, when 

subjected to a sustained heat flux from other burning cabin materials; 

therefore, the potential toxic hazard from evolved gases should also be 

considered when panels are selected for use in the closed environment of an 

aircraft cabin. 

In the laboratory, we have observed that the toxicity of pyrolysis 

products from aircraft cabin materials can vary markedly between flaming and 

nonflaming conditions and, to a lesser extent, can vary with pyrolysis 

temperature. Our previous studies utilized a combustion tube assembly 

completely encircled by a small annular furnace that provided radiant heat 

around the perimeter of the tube and conductive heat through the sample boat 

(2,3). However, this omnidirectional heat flux may not accurately reflect the 

conditions to which panels (and other flat surfaces) are likely to be exposed 

in an actual fire. Whether the source of the heat is from an external fuel 

fire heating the rear surface of the panel or from burning interior materials 

radiating heat onto the panel facing, the source (at least initially) is 

likely to be unidirectional. Under these conditions, the multilayer 

construction of many modern panels would cause the evolved gas composition 

(and thus toxicity) to vary as successive layers are pyrolyzed. Logically, 

the measured toxicity of the evolved gases from such composite panels would be 

more relevant if the pyrolysis mode more nearly reflected a probable real fire 

condition. 

The purpose of this study was to determine the relative toxicity of the 

combustion products from nine aircraft cabin panels, representing both 

composite and homogeneous construction, that were being tested concurrently 

for flammability and smoke production at the FAA Technical Center (4,s). We 

designed and constructed a combustionlexposure assembly in which panel 

sections were pyrolyzed by radiant heat directed onto the upper surface only; 

the relative toxicity of the evolved gases was measured by determining the 

effect (time-to-incapacitation) on the laboratory rat. We also determined the 

relative toxicity of gases from the same nine panels when pyrolyzed in the 

older (and smaller) combustion tube assembly in order to compare the effects 

of the different pyrolysis modes. 

Sample equivalency between the two systems was based on equal sample 

surface-area-to-volume ratios instead of the more familiar equal 

weight-to-volume ratios, a modification based on the principle that equal 

surface areas of all panels would be utilized in their final end-use 

application. 

1. 
MATERIALS 

Animals. Male albino rats of Sprague-Dawley origin were obtained from 

Charles River Breeding Laboratories, Wilmington, MA. They were ordered in a 

weight range of 100 to 120 g and were held in isolation for 8 days prior to 

use. All animals were inspected by a veterinarian on arrival and were 

maintained on drinking water containing 1.5 g/L of sulfathiazole for the first 

4 days, then normal tap water for the remaining 4 days of isolation; food and 

water were available continuously. 

Rats were fasted overnight before testing to establish an equivalent 

metabolic state; each animal was weighed and marked with an identifying color 

code just prior to use. 

Test Materials. Nine panels were received from the FAA Technical Center 

in Atlantic City, NJ, for toxicity testing. The numbering system and panel 

descriptions below were furnished by the Technical Center; panels 1 through 5 

are identical to the same numbered panels described in their improved 

flammability method tests (5). This numbering system is also used throughout 

this report. 

Panel No. 1 

Panel No. 2 

Panel No. 3 

Panel No. 4 

Panel No. 5 

Panel No. 6 

Panel No. 7 

Panel No. 8 

Panel No. 9 

Epoxy/Fiberglas honeycomb 

Phenolic/Fiberglas honeycomb 

EpoxylKevlar honeycomb 

Phenolic/Kevlar honeycomb 

Phenolic/Graphite honeycomb 

Polyether-ether-ketone/Polyimide/Fiberglas honeycomb 

Acrylonitrile-butadiene-styrene/Polyvinylchloride 

thermoplastic sheet 

Polycarbonate thermoplastic sheet 

Polyetherimide thermoplastic sheet 

Combustion/Exposure Assemblies. Two animal exposure systems were used in 

this study. The larger system (265 L) was equipped with a radiant heat unit 

designed to deliver heat to one side of the sample only. The smaller system 

(12.6 L) was equipped with a 2-inch combustion tube, enclosed by a cylindrical 

heating unit that provided radiant heat around the perimeter of the tube and 

conductive heat through a quartz combustion boat in contact with the tube wall. 

265-L System. The animal chamber, shown in Figure 1, was constructed from 

polymethylmethacrylate (PMMA) and has an internal volume of 203 L. A smaller 

42-i plenum, constructed from polycarbonate for heat resistance, was 

positioned at one end and over the combustion assembly to allow cooling and 

dilution of the hot gases. The cooled gases entered the animal chamber 

through two 7-cm-diameter P"A tubes. A flexible tube between the floor of 

the exposure chamber and the bottom of the combustion assembly provided 

continuous recirculation of the animal chamber air underneath and around the 

test sample, into the polycarbonate plenum, and back into the animal chamber. 

The experimental animals were contained in four 20-cm-diameter rotary cages 

mounted on a motor-driven shaft inside the animal chamber. Perimeter speed 

for the rotary cages (and required walking speed for the rats) was 6.4 cm/s. 

2. 
The combustion assembly was constructed from stainless steel with a 

triangular cross section; full-length quartz windows in the sides of the 

assembly allowed radiant heat from four 2,000-watt quartz lamps (two on each 

side) to impinge on the sample surface at approximately 45O angles. A 

hot-wire igniter was suspended approximately 1 cm above the sample position to 

ignite the evolved gases when flaming combustion was desired. The total 

system volume was 265 L, and the maximum test sample size was 7.6 by 22.9 cm 

(3 by 9 in). 

12.6-L System. The construction of this system has been described in 

detail in previous publications (2,3), and a diagram of the specific 

configuration used in this study is shown in Figure 2. Briefly, the animal 

chamber consisted of a P"A box containing a motor-driven rotating cage with 

compartments for three rats; perimeter speed for this cage was also 6.4 cm/s. 

A recirculating blower forced chamber air through the combustion tube, over 

the sample, and (mixed with the combustion gases) back into the animal 

chamber. Heat was applied to the test sample by a pair of 425-watt, 

semicylindrical heating units encircling the combustion tube; the total system 

volume was 12.6 L. A hot wire igniter was similarly available, if flaming 

combustion was desired. 

Analytical and Support Systems. Similar gas analysis systems were used 

for both chambers. The chamber atmosphere was continuously pumped through the 

sample loops of two gas chromatographs and back into the chamber, using a 

ceramic piston pump with Saran tubing connections. One gas chromatograph 

(with a thermistor detector) analyzed for carbon monoxide (CO) and oxygen 

(02) ; the other gas chromatograph (with a nitrogen-phosphorus detector) 

analyzed for hydrogen cyanide (HCN). Samples were analyzed at 1.8-min 

intervals for CO and 02 and at 3.6-min intervals for HCN. 

Oxygen was resupplied manually to the animal chamber when the 

concentration dropped below the normal ambient level. During flaming 

combustion, oxygen was added continuously while the sample was flaming; during 

nonflaming tests and post-burn observation periods, a lesser rate of addition 

was sufficient to maintain the chamber concentration between 90 percent and 

100 percent of the ambient level. Temperatures were monitored throughout the 

test period from thermocouples mounted in the animal chambers and in the 

combustion tube assembly. 

TEST PROCEDURE 

For tests in the 265-L system, a fasted and weighed albino rat was placed 

in each of the four rotating cages. The animal chamber, which consists of a 

203-L polymethylmethacrylate (PMMA) box, was fitted over the rotating cages 

and sealed against a gasket embedded in the chamber base. The adjoining 

mixing/cooling chamber (or plenum) was then connected to the animal chamber by 

two P"A tubes as shown in Figure 1. A 7.6- by 22.9-cm section of panel, 

conditioned overnight at 50 percent relative humidity, was weighed and placed 

in a combustion boat. The chamber was sealed; the oxygen resupply, gas 

sampling, and temperature monitoring equipment were connected; and the power 

control for the radiant heat assembly was set to supply the desired incident 

flux level. At zero time, the cage rotation motor, heater power supply, 

recirculating fans, timer, and (when used) the hot wire igniter were activated 

3. 
simultaneously. The test sample was observed for the first indication of 

decomposition (melting, smoke) and for ignition. Sampling (and analysis) of 

the chamber atmosphere began 1 min after initiation of the test. Oxygen was 

resupplied manually when the chromatographic analysis indicated a decrease 

below the ambient concentration. Time-to-incapacitation (ti) was noted when 

each rat could no longer perform the coordinated act of walking in the 

rotating cage (i.e., when sliding or tumbling began). When all rats were 

incapacitated, cage rotation was stopped. Time-to-death (td) was recorded 

when visible signs of respiration had ceased. Power to the radiant heat lamps 

was shut off at 10 min to prevent overheating the air in the exposure 

chamber. Animal obervations were limited to the 30-min test period. 

Tests in the small chamber (12.6 L) were performed in the same manner 

except for sample size and method of sample insertion. Since the cylindrical 

heating unit required several minutes to reach a stable temperature, the 

system was preheated to the desired temperature before inserting the sample. 

The test sample was placed in a quartz combustion boat and, at time zero, was 

inserted into the center of the heated area in the combustion tube. 

Two test conditions were selected for each system. One test was performed. 

at a low temperature (600 OC in the 12.6-L system) or low incident flux (5 

W/cm2 in the 265-L system) that would allow sample decomposition without 

spontaneous ignition (i.e., a nonflaming mode). The other condition utilized 

a higher temperature (750 OC in the 12.6-L system) combined with hot wire 

ignition of the evolved gases to insure flaming combustion. In the flaming 

test condition, the hot wire igniter was activated at initiation of the test 

and deactivated immediately after sample ignition. 

Each panel was tested twice under each of the four pyrolysis conditions. 

Three rats per test were exposed in the 12.6-L combustion tube assembly for a 

total of six rats exposed at each temperature. The 265-L radiant heat 

assembly accomodated four rats per test, allowing the exposure of eight rats 

at each heat flux level. 

At the end of each test, the sample residue was removed, cooled to room 

temperature, and weighed to determine the weight percent lost in each 

pyrolysis condition. Since most of the panels contained noncombustible (or 

extremely heat-resistant) materials, we pyrolyzed weighed sections of each at 

850 OC for 3.3 h to determine what fraction of the total weight was 

potentially combustible. This provided a standard for comparison of 

combustion efficiency for each system and condition. The percent of sample 

weight lost during pyrolysis (Table 2) was based on this weight of combustible 

material in the sample, not the total sample weight. 

The maximum sample size accommodated by the combustion boat in the 265-L 

system was 7.6 by 22.9 cm, and this size was selected for the initial panel 

tests. To obtain an equivalent area-to-volume ratio for the 12.6-L system, 

the surface area of the larger sample (174 cm2) was multiplied by the ratio 

of the relative chamber volumes. Squares of each panel, with sides 2.9 cm 

long, were cut to provide the calculated 8.3-cm2 equivalent surface area for 

the 12.6-L system. 

4. 
RESULTS AND DISCUSS ION 

It is evident from the data in Table 1 that only tests at the higher 

temperature (or higher heat flux) produced measurable animal responses from 

all nine panels during the 30-min observation period. Under less severe 

conditions, gases from some of the panels failed to incapacitate all the test 

animals. It is equally evident from the weight loss data (Table 2) that a 

proba'ble reason for some failures to incapacitate was that the more 

heat-resistant panels simply did not decompose sufficiently at the lower 

temperatures. At 600 OC in the 12.6-L system, panels 6, 9, and 5 lost 12 

percent, 20 percent, and 28 percent of their respective combustible weights. 

Only slightly greater decomposition was noted for these panels in the 265-L 

radiant heat system at the 5-W/cm2 level. 

At the higher temperature (and higher heat flux level), all panels 

decomposed to a greater extent. At 750 OC (flaming) in the 12.6-L system, 

all but two of the panels lost 99 percent to 100 percent of their combustible 

weight. The exceptions were panel No. 5, with a phenolic/graphite honeycomb 

construction, which lost approximately 90 percent, and panel No. 9, a 

homogeneous polyetherimide, which lost about 72 percent. In the 265-L radiant 

heat assembly at 7.5 W/cm2, panels 5 and 9 lost 51 percent and 54 percent 

respectively, while the remainder of the panels lost 75 percent to 97 percent 

of their total combustible weight. 

Panel rankings by animal response (ti) were not identical for any two of 

the four pyrolysis conditions. Within each condition, some of the mean 

response times differed only slightly and statistical analysis indicated no 

significant difference between them ( t- test, P.05 levell(6). Figure 3 

depicts the ranking of panels by mean ti's with those producing 

statistically like responses grouped together. 

We have previously considered that polymeric materials should be ranked 

for the toxicity of their combustion products by selecting the "worst case" 

condition (the test condition that produced the shortest ti) for each 

material, then ranking the materials from most toxic (shortest ti) to least 

toxic (longest ti). In this series of tests, the shortest ti's were those 

produced at 750 OC (flaming) in the 12.6-L system. In the 265-L radiant 

heat system, the shortest ti's were produced at the 7.5-W/cm2 (flaming) 

flux level. No "worst case" response was noted at the lower temperature (or 

lower heat flux) condition in either system. Therefore, the "worst case" 

ranking for the nine panels is depicted in Table 1, column 2, with all ti's 

selected from the 750 OC (flaming) condition in the 12.6-L combustion tube 

assembly. 

Some test performance characteristics of the panels can be described best 

on an idividual basis. A summary of characteristics noted during the toxicity 

testing follows. 

Panel No. 1, Epoxy/Fiberglas Honeycomb. This panel consistently produced 

ti's in the more toxic 15 percent of each ti range under all four test 

conditions. Smoke production was rapid, but of medium density. Peak CO 

5. 
production was 10,641 ppm and peak HCN was 340 ppm; both peak levels were 

recorded in the 750 OC (flaming) tests in the 12.6-L chamber. The panel 

contained 42 percent by weight of noncombustible material (at 850 Oc for 

3.3 h). 

Panel No. 2, Phenolic/Fiberglas Honeycomb. This panel exhibited variable 

toxicity with the different test conditions; it produced ti's in the more 

toxic 15 percent of each range at 600 OC (12.6 L) and 5 W/cm2 (265 L) but 

fell into the mid- to low-toxicity ranges at the higher temperatures. Peak 

HCN (201 ppm) and CO (10,878 ppm) values were both recorded at 600 OC in the 

12.6-L assembly. Visible smoke production was of low to medium density. 

Noncombustible material comprised 51 percent of the total weight of this panel. 

Panel No. 3, Epoxy/Kevlar Honeycomb. In all four test conditions, panel 

No. 3 produced ti's in the most toxic 5 percent of each ti range. Very 

dense smoke was produced, particularly at the higher temperatures. Peak HCN 

was 600 ppm (7.5 W/cm2, 265-L system) and peak CO was 9,105 pprn (600 OC, 

12.6-L system). Noncombustible material was less than 3 percent of the total 

panel weight. 

Panel No. 4, Phenolic/Kevlar Honeycomb. This panel produced ti's in the 

more toxic 20 percent of each ti range for all four test conditions. Very 

dense smoke was produced at the higher temperatures but cleared rapidly after 

heating ceased. Peak HCN was 534 ppm (at 5 W/cm2) and peak CO was 9,398 ppm 

(at 7.5 W/cm2), both in the 265-L system. Approximately 3 percent of the 

panel weight was noncombustible material. 

Panel No. 5, Phenolic/Graphite Honeycomb. Under all test conditions, the 

ti's for panel No. 5 were found to be near the middle of each range. Smoke 

density was minimal, and production of CO and HCN was moderate. Maximum CO 

(6,832 ppm) was detected at 750 OC in the 12.6-L system and maximum HCN (250 

ppm) was 5 W/cm2 in the 265-L system. Less than 2 percent of the sample 

weight was noncombustible material. 

- 

Panel No. 6, Polyether-ether-ketone/Polyimide/Fiberglas Honeycomb. Animal 

responses to this heat-resistant panel varied with the test temperatures; 

ti's were in 

temperatures 

600 OC (12.6- 

the more toxic 20 percent of each range at the higher 

(750 OC and 7.5 W/cm2) , were midrange at 5 W/cm2, and, at 

.L system), none of the animals were incapacitated. Very little 

visible smoke was produced at any test temperature. Peak CO concentration was 

14,249 ppm, and peak HCN was 537 ppm; both peak values were recorded at 

750 OC in the 12.6-L combustion tube assembly. Approximately 57 percent of 

the panel was noncombustible material. 

Panel No. 7, Acrylonitrile-butadiene-styrene/Polyvinylchloride. Animal 

response times for this panel were in the more toxic 25 percent of each range 

at 5.0 and 7.5 W/cm2 (265-L system) and at 750 OC (12.6-L system). At 

600 OC (12.6-L system), none of the animals were incapacitated during the 

observation period. This panel produced very dense, white smoke under all 

test conditions; smoke density was of sufficient magnitude to make animal 

observation difflcult. The maximum CO (11,132 ppm) and HCN (749 ppm) 

concentrations were both recorded in the 265-L radiant heat system at the 

7.5-w/Cm2 flux level. Noncombustible material was less than 4 percent. 

6. 
Delayed autoignition of the combustion gases occurred twice during the 

testing of panel No. 7 at 5 W/cm2 in the 265-L radiant heat assembly. The 

resulting "soft" explosions were confined to the polycarbonate mixing/cooling 

chamber, and the overpressure was relieved by the opening of the blowout panel 

(the top cover of the polycarbonate plenum). The white smoke cleared quickly 

after ignition occurred, and heavy soot deposits rapidly covered the interior 

chamber walls. No damage to the chamber resulted. 

Panel No. 8, Polycarbonate Thermoplastic Sheet. At the higher 

temperatures, the polycarbonate sheet produced ti's in midrange; lower 

temperatures produced longer ti's near the bottom of the respective ranges. 

Relatively dense smoke was produced under all test conditions, with the smoke 

density reaching its peak more rapidly at the higher temperatures. The 

maximum CO concentration (15,188 ppm) was detected at 750 OC in the 12.6-L 

system; no measurable HCN was produced under any of the test conditions. 

Noncombustible material was less than 2 percent. 

Panel No. 9, Polyetherimide Thermoplastic Sheet. This material was the 

least toxic of all nine panels under all test conditions. Moderate to heavy 

white smoke was produced, usually developing late in the test (6 to 7 min) at 

the lower temperatures. Peak CO concentration (3,843 ppm) was detected in the 

265-L system at 7.5 W/cm*. A peak HCN concentration of 133 ppm was recorded 

at 750 OC in the 12.6-L system, but no measurable HCN was detected under any 

of the other test conditions. This panel contained about 21 percent 

noncombustible material, but less than 75 percent of the remaining combustible 

content was pyrolyzed by the most severe pyrolysis condition (750 OC, 12.6-L 

combustion tube system). 

SUMMARY AND CONCLUS IONS 

We have described the testing of nine aircraft panels for the relative 

toxicity of their gaseous combustion products in two different 

laboratory-scale combustion/exposure systems and under flaming and nonflaming 

conditions. One system was designed to thermally decompose the flat panel 

samples by radiant heat impinging on the upper surface only; the second system 

decomposed samples by a combination of conductive and omnidirectional radiant 

heat inside a quartz combustion tube. Time-to-incapacitation in the 

laboratory rat was the response used to compare the toxicity of the panel 

combustion gases; relative toxicity within each system was based on the animal 

responses observed when equal surface areas of each panel were pyrolyzed. 

Sample surface areas proportional to the respective system volumes were used 

for comparisions between the two combustion/exposure systems. 

Only the higher temperatures in both the radiant heat and the combustion 

tube systems proved suitable for toxicological differentiation between the 

panels. Lower temperatures (and heat flux levels) failed to pyrolyze some of 

the more heat-resistant panels to the extent that would reliably produce an 

animal response within the observation period. 

7. 
The ''worst case'' condition for all panels (the test condition that 

produced the shortest ti's) across all conditions was the 750 OC flaming 

test in the 12.6-L combustion tube assembly. Times-to-incapacitation for this 

condition were not widely separated but fell into approximately the th.ree 

groups shown below. 

(Most toxic) Panels 1, 3, 4, 6, 7 (ti's: 3.3 to 4.1 min) 

(Midrange) Panels 5, 8 (ti's: 6.1 min for both) 

(Least toxic) Panels 2, 9 (ti's: 7.3 and 9.1 min) 

A similar panel grouping is shown below for the animal response times 

recorded in the 265-L radiant heat assembly; all of the shortest response 

times (for this system) occurred during the 7.5-W/cm2 tests. 

(Most toxic) Panels 1, 3, 4, 7 (ti's: 7.3 to 8.3 min) 

(Midrange) Panels 2, 6, 8 (ti's: 9.3 to 10.0 min) 

(Least toxic) Panels 5, 9 (ti's: 12.4 and 17.7 min) 

As indicated above (and in Table l), the higher temperature in each system 

produced similar, but not identical, potential toxicity rankings for the nine 

panels. The combustion tube assembly produced shorter ti's and equal or 

higher peak CO and HCN concentrations than did the radiant heat furnace. The 

combustion tube also produced a more rapid development of the peak gas 

concentrations from the thicker panels with the honeycomb type of 

construction; little or no such effect was observed with the thinner, 

homogeneous thermoplastic sheets (panels 7, 8, and 9). 

All panels, except the polycarbonate sheet (panel No. 8) produced HCN 

under the "worst case" condition (750 OC, flaming). Under the same 

condition, all panels produced lethal peak concentrations of CO, with the 

highest (from panels 1, 6, and 8) exceeding 10,000 ppm. Except for these 

three panels, peak CO concentrations were similar at the high temperature 

conditions in both combustion systems. 

At the high temperature conditions (750 OC and 7.5 W/cm2) , which are 

near the practical upper limits for both combustion systems, sample 

decomposition (at 10 min) was more nearly complete in the combustion tube 

furnace than in the radiant heat assembly (Table 2). This higher combustion 

efficiency exists even though the radiant heat flux, measured inside the 

combustion tube at 750 OC, is less (5.2 to 5.4 W/cm2) than the 

corresponding unidirectional flux (7.5 W.cm2) in the radiant heat furance. 

This increased rate of decomposition in the combustion tube appears to be due 

to the omnidirectional nature of the heat flux, which does not allow one side 

of the sample to insulate the other, and possibly to the added heat input 

8. 
supplied by conduction. However, despite the somewhat lesser efficiency of 

the radiant furnace, some investigators feel that this combustion method may 

more closely approximate the conditions to which panels (and other flat 

surfaces) are exposed in a real cabin fire and may, therefore, produce a more 

realistic measure of relative potential toxicity for this particular class of 

materials. 

9. 
2 3 4 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

AIR FLOW 13 

FIGURE 1. COMBUST ION/EXPOSURE ASSEMBLY (265 L) 

Animal exposure chamber 

Gas sampling inlet 

Oxygen inlet 

Thermocouple (air temperature) 

Muffin fan (recirculation assembly); Rotron Manufacturing Company, 

Woodstock, NY 

Chamber connecting tubes 

Mixing/cooling chamber 

Gas deflector 

Hot wire igniter 

Heat lamp reflector with two 2,000-watt General Electric quartz lamps 

(GE QH2M/T3/CL/HT 240 V) 

Sample combustion chamber 

Sample combustion boat (stainless steel, for 7.6- by 22.9-cm sample) 

Combustion chamber air plenum 

Flexible tube, 10-cm-diameter (to supply air to the sample combustion 

chamber) 

Muffin fan (for mixing chamber air) 

Cage motor drive shaft and axle support 

Individual rotating cage 

10. 
1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

FIGURE 2. COMBUSTION/EXPOSURE ASSEMBLY (12 6 L) 

Gearmotor, model 3M126, 6 rpm, 1/20 hp; Dayton Manufacturing Company, 

Chicago, IL 

Animal exposure chamber 

Heating unit, model NV2X6, 425 W at 57.5 V, semicylindrical; Watlow 

Electric Manufacturing Co., 12001 Lackland Road, St. Louis, MO 

Same as No. 3 

Thermocouple, chromel-alumel; Omega Engineering Inc., Stamford, CT 

Hot wire igniter 

Combustion tube, quartz, 2-inch-diameter 

Combustion boat 

Spring clamp 

Smoke detector 

11. 
FIGURE 3. TOXICITY RANKING OF PANELS BY 

MEAN T IMES-TO- INCAPAC ITAT ION 

~~~ 

Combustion Tube 

Min 6OO0C 750 OC FL 

* 

L 

-5 

-8 

** 

Radiant Furnace 

5 W/cm2 7.5 W/cm2 FL 

131 

-2,3 

/I 

1413.71 

I 4 

'5 [a] 

-9 

sc Mean ti's for panel numbers in boxes to the right of each column were not 

statistically different by t-test at the P.05 level (6). 

** Panels 6, 7, and 9 did not produce incapacitation in 30 min at 600 OC. 

N = Six rats per temperature condition for combustion tube tests and eight 

rats per heat flux level for the radiant furnace tests. 

FL = flaming combustion, hot wire igniter used. 

12. 
TABLE 1. TOXICITY RANKING OF AIRCRAFT PANEL MATERIALS BY 

T IME-TO- INCAPAC ITAT ION FOR FOUR TEST COND IT IONS 

Combustion Tube Radiant Furnace 

600 OC 750 OC, FL 5 W/crn2 7.5 W/cm2, FL 

Panel t * Panel ti 3 Panel ti 3 Panel ti 3 

Rank* Number mln Number mln Number mln Number mln 1’ 

- 

1 1 a. 1 3 3.3 2 10.7 4 7.3 

2 3 8.4 7 3.6 3 10.7 3 7.4 

3 4 10.0 1 3.7 1 12.3 7 7.8 

4 2 10.1 4 3.9 4 12.8 1 8.3 

5 5 13.9** 6 4.1 7 13.9 6 9.3 

6 a 17.8 5 6.1 5 14.2 a 9.6 

7 6 NR-30 8 6.1 6 14.7 2 10.0 

a 7 NR-30 2 7.3 a 23.1** 5 12.4 

9 9 NR-30 9 9.1 9 23.7** 9 17.7 

FL = Flaming combustion, hot wire igniter used. 

NR-30 = No animal response within the 30-min observation period. 

* Materials are ranked from No. 1 (most toxic, shortest ti) to No. 9 (least 

toxic, longest ti). 

** The mean ti shown is for a single test only; in the second test, one or 

more animals were not incapacitated during the observation period. 

13. 
TABLE 2. PERCENT OF TOTAL COMBUSTIBLE WEIGHT 

LOST DURING TEST* 

Panel Test Combustion Tube Radiant Furnace 

600 OC 750 OC , FL 5 w/cm2 7.5 W/cm2, FL 

1. Epoxy/Fiberglas 1 92 99 

Honeycomb 2 92 99 

2. Phenolic/Fiberglas 1 -- 98 

Honeycomb 2 81 100 

3. Epoxy/Kevlar 

Honeycomb 

1 68 100 

2 75 100 

-- 97 

78 96 

77 94 

67 94 

82 94 

80 94 

4. Phenolic/Kevlar 1 -- 100 74 96 

Honeycomb 2 66 100 61 90 

5. Phenolic/Graphite 1 28 96 38 51 

Honeycomb 2 22 84 30 51 

6. Polyether-ether- 1 12 100 37 79 

ketone/Polyimide/ 2 ST 100 23 70 

Fiberglas Honeycomb 

7. Acrylonitrile- 1 92 100 97 98 

butadiene-styrene/ 2 ST 100 94 96 

Polyvinylchloride 

8. Polycarbonate 1 82 100 

Thermoplastic Sheet 2 75 100 

78 87 

73 88 

9. Polyetherimide 1 20 74 22 53 

Thermoplastic Sheet 2 ST 70 18 54 

-- Indicates residue not weighed; i.e., not recovered intact. 

* Percent of combustible weight lost was calculated by dividing the weight 

loss fraction of the sample pyrolyzed under the test condition by the weight 

loss fraction of a corresponding sample pyrolyzed for 3.3 h at 850 OC and 

multiplying the quotient by 100. 

FL = Flaming combustion, hot wire igniter was used. 

ST = Single test only, CO + HCN were insufficient to produce incapacitation at 

this condition. The notation applies to the 600 OC combustion tube tests 

only. 

14. 
REFERENCES 

1. Airworthiness Standards: Transport Category Airplanes, DOT/FAA, Federal 

Aviation Regulations, Vol. 111, Part 25, Transmittal 10, effective May 1, 

1972. 

2. Crane CR, Sanders DC, Endecott BR, Abbott JK, Smith PW. Inhalation 

Toxicology: I. Design of a Small-Animal Test System. 11. Determination 

of the Relative Toxic Hazards of 75 Aircraft Cabin Materials. 

Washington, DC: Federal Aviation Administration Office of Aviation 

Medicine Report No. FAA-AM-77-9, 1977. 

3. Crane CR, Sanders DC, Endecott BR, Abbott JK. Inhalation Toxicology: 

III. Evaluation of Thermal Degradation Products from Aircraft and 

Automobile Engine Oils, Aircraft Hydraulic Fluid, and Mineral Oil. 

Washington DC: Federal Aviation Administration Office of Aviation 

Medicine Report No. FAA-AM-83-12, 1983. 

- 

Administration Report No. DOT/FAA/CT-84/14, 1984. 

5. Sarkos CP, Filipczak RA, Abramowitz A. Preliminary Evaluation of an 

Improved Flammability Test Method for Aircraft Materials. 

Washington, DC: Department of Transportation/Federal Aviation 

Administration Report No. DOT/FAA/CT-84/22, 1984. 

6. Steel KCD, Torrie JH. Principles and Procedures of Statistics. 

New York: McGraw-Hill, 1960. 

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