Evaluation of the 12-Second Vertical 

Bunsen Burner Test Used to 

Determine the Fireworthiness of 

Aircraft Duct Materials 

John W. Reinhardt 

October 2005 

DOT/FAA/AR-TN05/36 

This document is available to the public through the National 

Technical Information Service (NTIS), Springfield, Virginia 22161. 

U.S. Department of Transportation 

Federal Aviation Administration

ote technical note technic

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NOTICE 

This document is disseminated under the sponsorship of the U.S. 

Department of Transportation in the interest of information exchange. 

The United States Government assumes no liability for the contents or 

use thereof. The United States Government does not endorse products 

or manufacturers. Trade or manufacturer's names appear herein solely 

because they are considered essential to the objective of this report. This 

document does not constitute FAA certification policy. Consult your local 

FAA aircraft certification office as to its use. 

This report is available at the Federal Aviation Administration William J. 

Hughes Technical Center’s Full-Text Technical Reports page: 

actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF). 
Technical Report Documentation Page 

1. Report No.

DOT/FAA/AR-TN05/36 

2. Government Accession No. 3. Recipient's Catalog No.

5. Report Date 

October 2005

4. Title and Subtitle

EVALUATION OF THE 12-SECOND VERTICAL BUNSEN BURNER TEST 

USED TO DETERMINE THE FIREWORTHINESS OF AIRCRAFT DUCT 

MATERIALS 

6. Performing Organization Code

7. Author(s)

John W. Reinhardt 

8. Performing Organization Report No.

9. Performing Organization Name and Address

Federal Aviation Administration 

William J. Hughes Technical Center 

Airport and Aircraft Safety 

10. Work Unit No. (TRAIS)

Research and Development Division 

Fire Safety Branch 

Atlantic City International Airport, NJ 08405 

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

U.S. Department of Transportation 

Federal Aviation Administration

13. Type of Report and Period Covered

Technical Note

Office of Aviation Research 

Washington, DC 20591 

14. Sponsoring Agency Code

ANM-110 

15. Supplementary Notes

16. Abstract

This technical note provides the technical approach and test results of the evaluation of the currently used Federal Aviation 

Administration certification test, known as the 12-second vertical Bunsen burner test, to certify aircraft ducts and conduits. 

17. Key Words

Air conditioner ducts, Vertical Bunsen burner, OSU Heat 

Release Test, NBS smoke test, Intermediate-scale fire test, 

Microscale combustion calorimeter, Glass/epoxy laminate, 

Urethane foam core 

18. Distribution Statement

This document is available to the public through the National 

Technical Information Service (NTIS), Springfield, Virginia 

22161.

19. Security Classif. (of this report)

Unclassified 

20. Security Classif. (of this page)

Unclassified 

21. No. of Pages

27 

22. Price

Form DOT F1700.7 (8-72) Reproduction of completed page authorized 
TABLE OF CONTENTS 

Page 

EXECUTIVE SUMMARY vii 

1. INTRODUCTION 1 

2. TECHNICAL APPROACH 1 

3. TEST RESULTS 3 

3.1 Twelve-Second Vertical Bunsen Burner Test 3 

3.2 Intermediate-Scale Narrow-Body Fire Test 3 

3.3 The OSU Heat Release Rate Test 3 

3.4 Microscale Combustion Calorimeter 4 

3.5 The NBS Smoke Test 4 

3.6 Radiant Panel Test 4 

4. CONCLUSION 4 

iii
LIST OF FIGURES 

Figure Page 

1 Vertical Bunsen Burner Test 5 

2 Bunsen Burner Heat Profile Instrumentation Setup 5 

3 Urethane Foam Heat Profile Instrumentation Setup 5 

4 Intermediate-Scale Setup With Ignition Source Only 6 

5 Intermediate-Scale Setup With Air Conditioning Duct 7 

6 Narrow-Body Aircraft Air Conditioning Overhead Duct 8 

7 Air Conditioning Overhead Duct in Aircraft Attic 8 

8 Intermediate-Scale Setup 9 

9 Vertical Bunsen Burner Posttest 9 

10 Intermediate-Scale Fire Test 10 

11 Intermediate-Scale Test Temperature History 10 

12 Intermediate-Scale Test Calorimeter History 11 

13 Posttest Condition of Air Conditioning Duct 11 

14 Heat Release Test Run 1 12 

15 Heat Release Test Run 2 12 

16 Heat Release Test Run 3 13 

17 The NBS Smoke Test Run 1 13 

18 The NBS Smoke Test Run 2 14 

19 The NBS Smoke Test Run 3 14 

20 The NBS Smoke Test Run 4 15 

21 Radiant Heat Panel Test of Air Conditioning Duct Material 15 

22 Radiant Heat Panel Posttest Duct Condition 16 

iv
LIST OF TABLES 

Table Page 

1 Tests Results 17 

2 Heat Source Profile 18 

v
LIST OF ACRONYMS 

CFR Code of Federal Regulations 

FAA Federal Aviation Administration 

NBS National Bureau of Standards 

OSU Ohio State University 

vi
EXECUTIVE SUMMARY 

Because of the desire to improve in-flight fire safety, the Federal Aviation Administration (FAA) 

is examining the adequacy of the fire test requirements for inaccessible area materials, including 

electrical wiring and air conditioning ducts. This activity is a continuation of prior work that 

resulted in the development and adoption of improved fire test criteria for thermal acoustic 

insulation. The current test requirement for air conditioning ducts is the 12-second vertical 

Bunsen burner test (Title 14 Code of Federal Regulations Part 25, Appendix F Part I (a)(4)). The 

FAA goal is to elevate the in-flight fire performance of all major inaccessible materials to the 

same level as now required for thermal acoustic insulation. 

The technical approach selected was to conduct intermediate-scale fire tests on ducting that 

meets the Bunsen burner test criteria, subjected to a standard intense fire source. An equivalent 

level of fire performance with the behavior of improved thermal acoustic insulation will be 

exhibited if the air conditioning duct does not propagate a flame when subjected to the standard 

fire. The ducting was removed from a surplus test aircraft and was a composite comprised of 

epoxy/fiberglass facings and a urethane foam core. 

Additional fire tests were conducted on the duct material, although not required by federal 

regulations. The fire tests were the Ohio State University (OSU) rate of heat release test, the 

National Bureau of Standards (NBS) smoke test, radiant panel test, and the microscale 

combustion calorimeter test. These tests characterized the overall fireworthiness of the material 

and provided some indication of the adequacy of the current vertical Bunsen burner test method. 

The duct material passed the 12-second vertical Bunsen burner test even after 25 years of service 

and possibly containing some unknown level of contamination. The burn length on the samples 

was between 6.99 and 7.62 cm; the regulation allows a maximum burn length of 20.32 cm. The 

material did not drip, and the flame-extinguishing time was zero (no flames after removing the 

burner) in two of the three tests. During the third test, the flames self-extinguished in 8 seconds. 

The regulation allows a maximum flame-extinguishing time of 15 seconds. During the 

intermediate-scale fire test, large quantities of flames and smoke were observed exiting the 

forward and aft upper sections of the fuselage. Posttest observations revealed that the fire 

completely consumed the duct material. The maximum temperature on the ceiling was 835°C, 

and the maximum heat flux was 63.2 kW/m2

. It was clear that the vertical Bunsen burner test 

does not ensure the same level of fire performance as exhibited by improved thermal acoustic 

insulation meeting recently adopted stringent fire test criteria. 

During the OSU heat release tests, flames were immediately observed on the exposed face of the 

specimen, and a large quantity a smoke was emitting through the exhaust stack. The recorded 

data showed that the peak heat release exceeded the federal regulation-allowed value. The 

regulation allows a maximum heat release of 65 kW/m2; the results ranged from 74.34 kW/m2 to 

87.86 kW/m2

. The microscale combustion calorimeter test results indicated that the sample 

fiberglass and epoxy laminate had a heat release capacity of 123.0 J/g-K, a total heat release of 

13.4 KJ/g, and a char of only 12.6%. The urethane foam had a very high heat release capacity of 

436.0 J/g-K, a total heat release of 24.7 KJ/g, and a char of only 2.9%. The results of the NBS 

smoke test indicated that this material passed. The radiant panel test is the new stringent test 

vii
requirement for thermal acoustic insulation. The results showed that the duct material performed 

poorly. Only seconds after exposing the material specimen to the radiant heat and torch flame, 

the entire sample was engulfed in flames. The test was immediately terminated to prevent fire 

damage to the radiant panel. Two additional specimens were tested and both performed 

similarly. 

Based on the test results, especially the intermediate-scale test where a raging fire was 

experienced, it was concluded that the current FAA-required 12-second vertical Bunsen burner 

test is not an adequate test discriminator method to achieve the FAA’s fire performance goal for 

ducting material and that an improved fire test method and criteria for ducting materials should 

be developed. 

viii
1. INTRODUCTION. 

The objective of this evaluation program was to determine the adequacy of the current Federal 

Aviation Administration (FAA) fire test requirement for air conditioning ducts and electrical 

conduits. The current test is specified in Title 14 Code of Federal Regulations (CFR) Part 25, 

Appendix F Part I (a)(4) and is commonly referred to as the 12-second vertical Bunsen burner 

test. The overall FAA goal is to improve airplane standards such that fires in inaccessible areas 

do not spread and create catastrophic conditions. The goal is being addressed, in part, by 

examining the fire test standards for interior materials located in inaccessible areas, including air 

conditioning ducts. 

2. TECHNICAL APPROACH. 

The technical approach was to conduct intermediate-scale fire tests in a mockup of the area 

above the cabin ceiling (attic) on ducting compliant with the current flammability test 

requirement. This was the approach taken during the development of improved fire test criteria 

for thermal acoustic insulation. During this prior testing, a standard severe fire source was 

employed, consisting of a block of urethane foam saturated with heptane. Improved fire test 

criteria for insulation were developed from this earlier study, based on a requirement that a fire 

would not propagate when subjected to the standard foam ignition source in the intermediatescale test article. The FAA’s goal is to upgrade the fire performance of the remaining major 

inaccessible materials, including ducting, conduit, and electrical wirings to the same level as now 

required for insulation. Thus, the adequacy of the current flammability test requirement for 

ducting is based on the intermediate-scale performance of ducting compliant with the vertical 

Bunsen burner test requirement when subjected to the standard foam fire source. If compliant 

ducting prevents fire spread for a representative sampling of ducting materials, then the test 

requirement could be judged to be adequate; however, if fire spread occurs on any sample, then 

the test requirement is judged to be inadequate. 

The current federal aviation regulation related to the subject dictates that any duct installed 

onboard an aircraft after 1967 must meet, as a means of compliance, the 12-second vertical 

Bunsen burner fire test. To pass this test, any flames present on the 75- by 305-mm material 

sample after the fire source has been removed must self-extinguish within 15 seconds, and the 

burn length shall not exceed 203.2 mm. In addition, any material that melted and fell to the base 

of the cabinet shall not burn for more than 5 seconds (see section 2.1 for details). 

An overhead duct, which had been in a narrow-body cargo aircraft since 1980, was used for the 

test. The duct was a composite made of fiberglass and epoxy facings and urethane foam core. 

The entire duct section was fire tested in the intermediate-scale attic fire test article after it was 

determined that samples obtained from the duct were found to be compliant with the vertical 

Bunsen burner test requirement (figure 1). 

In addition, this duct material was evaluated using other FAA tests such as the Ohio State 

University (OSU) rate of heat release apparatus, the National Bureau of Standards (NBS) smoke 

chamber, cone calorimeter, and the microscale combustion calorimeter. These fire tests were 

expected to help characterize the overall fireworthiness of the material. The temperature and 

heat flux profiles of the ignition sources were recorded for each test to determine their severity. 

1
Examples of the instrumentation used to measure temperature and heat flux of various ignition 

sources are shown in figures 2 and 3. The following references the test procedures that are used. 

• The Vertical Bunsen Burner Test for Cabin and Cargo Compartment Materials test was 

conducted according to FAA report DOT/FAA/CT-89/15, “Aircraft Material Fire Test 

Handbook,” September 1990, see chapter 1 for more details. Also, see Title 14 Code of 

Federal Regulations (CFR) Part 25, Appendix F, Part I. 

• The Intermediate-Scale Narrow-Body Mock-Up Test was conducted according to FAA 

report DOT/FAA/AR-99/44, “Development of Improved Flammability Criteria for 

Aircraft Thermal Acoustic Insulation.” 

• The Heat Release Rate Test For Cabin Materials test was conducted according to FAA 

report DOT/FAA/CT-89/15, “Aircraft Material Fire Test Handbook,” September 1990, 

see chapter 5 for more details. Also, see 14 CFR Part 25, Appendix F, Part IV. 

• The Microscale Combustion Calorimeter test was conducted as discussed in FAA report 

DOT/FAA/AR-01/117, “A Microscale Combustion Calorimeter,” January 2002.

• The Smoke Test For Cabin Materials test was conducted according to FAA report 

DOT/FAA/CT-89/15, “Aircraft Material Fire Test Handbook,” September 1990, see 

chapter 6 for more details. Also, see 14 CFR Part 25, Appendix F, Part V.

• The Test Method to Determine the Flammability and Flame Propagation Characteristics 

of Thermal/Acoustic Insulation Materials test was conducted according to FAA report 

DOT/FAA/AR-89/15, “Aircraft Material Fire Test Handbook,” September 1990, see 

chapter 23 for more details. Also, see 14 CFR Part 25, Appendix F, Part VI. 

The upper half of a narrow-body fuselage section was used to conduct the intermediate-scale 

tests, as shown in figures 4 and 5. This section was insulated with thermal-acoustic insulation 

blankets fabricated with metallized Tedlar® (Orcon AN54W) and fiberglass (Johns Manville 

0.34 PCF Fiberglass). To simulate the cabin ceiling and create the attic space, a steel frame was 

installed to hold the composite ceiling panels in place. The ceiling panels, constructed of 

fiberglass/phenolic faces and a Nomex honeycomb core, were installed 330.2 mm below the 

crown of the fuselage section, and were compliant with the FAA-required heat release rate and 

smoke emissions standards. The attic space, formed by the ceiling panels and fuselage crown, 

was instrumented with thermocouples and calorimeters to measure the temperature and heat flux 

above the ignition source and at each end of the fuselage section. The thermocouples and 

calorimeters were connected to a portable data acquisition system, and their signal outputs were 

collected at a rate of 1 Hz. At least two cameras were set up to record the fire event. 

Photographs were also taken before and after each test to record the event and damage. 

Prior to installing the duct (see figure 6) in the narrow-body fuselage test rig (see figure 7), a 

baseline test was conducted to measure the ignition source temperature and heat flux (see 

figure 4). The ignition source for the intermediate-scale tests was a 101.6- by 101.6- by 

228.6-mm urethane foam block spiked with 10 cc of heptane. This foam block was placed in the 

2
middle of the fuselage section, but offset 215.9 mm (face of foam block) to the starboard side of 

the fuselage centerline. The test was initiated by starting the data acquisition system and 

activating the video cameras. Thirty seconds after collecting the ambient temperature data, the 

foam block was ignited and allowed to burn until the foam was consumed and the flames were 

out. The same test procedure was used when the air conditioning duct was mounted on the 

fuselage rig (see figure 8), but the fire was allowed to burn until the flames were out, or close to 

it, without damaging the test fixture (fuselage). The temperature and heat flux for all the tests 

were determined using the collected data. After each test, photographs of the test specimen were 

taken and the fire damage was recorded and measured. This test was conducted only once 

because of the severity of the results. 

3. TEST RESULTS. 

All the results from the various tests were tabulated and are shown in table 1. Table 1 includes 

the results and comments of the 12-second vertical Bunsen burner tests, intermediate-scale tests, 

OSU heat release rate tests, microscale combustion calorimeter tests, NBS smoke tests, and 

radiant panel heat tests. The heat source profiles of the different tests conducted were tabulated 

and are shown in table 2. 

3.1 TWELVE-SECOND VERTICAL BUNSEN BURNER TEST. 

Prior to testing the sample with this standard test, the flame temperature and heat flux of the test 

apparatus were measured, as shown in figure 2. The flame temperature was 925°C, and the heat 

flux was 40.6 kW/m2. The test results indicated that the duct material met the current federal 

aviation regulation, even though the material had been in service since 1980 and unknown 

contaminants were present. The burn length was between 6.99 and 7.62 cm; the regulation 

allows a maximum burn length of 20.32 cm (see figure 9). The material did not drip and flameextinguishing time was zero (no flames after removing the burner) in two of the three tests. 

During the third test, the flames self-extinguished in 8 seconds. The regulation allows a 

maximum flame extinguishing time of 15 seconds. 

3.2 INTERMEDIATE-SCALE NARROW-BODY FIRE TEST. 

The duct started to burn about 15 seconds after the foam block (ignition source) was ignited. 

After the fire penetrated the duct wall, the fire intensified and spread rapidly, apparently due to a 

chimney-like effect. Within a short period of time after penetration, the fire had spread to both 

ends of the test article with large flames and copious amounts of smoke rising into the air, as 

shown in figure 10. The maximum temperature recorded on the ceiling was 835°C, and the 

maximum heat flux recorded was 63.2 kW/m2

, as shown in figures 11 and 12. The fire burned 

intensely for over 6 minutes before it was extinguished. The severity of the duct fire was greater 

than observed previously with various grades of thermal acoustic insulation. Posttest 

observations revealed that the fire completely consumed the duct material, as shown in figure 13. 

3.3 THE OSU HEAT RELEASE RATE TEST. 

This test was repeated three times in the OSU apparatus. During the tests, flames were 

immediately observed on the exposed face of the specimen and a large quantity of smoke was 

3
emitted through the exhaust stack. Figures 14 through 16 show the heat release rate histories. 

The double peaks appear to correspond to the burning facing initially, followed by the 

involvement of the urethane core. The peak heat release rate exceeded the allowable value of 

65 kW/m2

. The peak heat release rates ranged from 74.34 kW/m2 to 87.86 kW/m2. 

3.4 MICROSCALE COMBUSTION CALORIMETER.

The fiberglass and epoxy laminate (facing) sample had a heat release capacity of 123.0 J/g-K, a 

total heat release of 13.4 KJ/g, and a char of 12.6%. The urethane foam core sample had a heat 

release capacity of 436.0 J/g-K, a total heat release of 24.7 KJ/g, and a char of 2.9%. The 

urethane foam is particularly flammable, as evidenced by the relatively high heat release capacity 

and low char yield. 

3.5 THE NBS SMOKE TEST. 

The duct sample was relatively smokey, although the maximum specific optical density did not 

exceed the allowable 200 value. As shown in figures 17 through 20, Dm values ranged from 120 

to 145. 

3.6 RADIANT PANEL TEST. 

The duct sample exhibited extreme flammability behavior in the radiant panel test. Only seconds 

after exposing the material specimen to the radiant heat and torch flame, its upper layer ignited 

quickly, engulfing the whole panel in flames. The test was not allowed to continue for the 

required duration of the test to prevent fire damage to the radiant panel. Two material specimens 

were tested and both performed similarly, as shown in figures 21 and 22. 

4. CONCLUSION.

The evaluation test results showed that the current flammability test method and criteria to 

certify aircraft ducts, i.e., the 12-second vertical Bunsen burner test, is not adequate to predict the 

behavior of ducts under realistic fire conditions. Therefore, an improved fire test method and 

criteria should be developed and assessed in the overall consideration of improved in-flight fire 

safety. 

4
FIGURE 1. VERTICAL BUNSEN BURNER TEST 

19 mm Calorimeter

Flame Heat Flux: 40.6 kW/m

Bunsen Burner

Flame Height: 38 mm

Flame Temperature: 925 C

Calorimeter

Holder

Thermocouple

2

FIGURE 2. BUNSEN BURNER HEAT PROFILE INSTRUMENTATION SETUP 

Foam Block

(Ignition Source)

Calorimeter

Thermocouple

0.32 cm

3.175 cm

3.81 cm

Calorimeter

Holder Fixture

FIGURE 3. URETHANE FOAM HEAT PROFILE INSTRUMENTATION SETUP 

5
Composite 

Ceiling Panel

Fire Ignition Source

(Urethane Foam Block 

Soaked with 

10 cc of Heptane)

365.76 cm

313.69 cm

T1, T2, T3

C1, C2, C3

Note:

 T# - Thermocouple

 C# - Calorimeter

 Sensors 2.54 cm apart

Thermoacoustic Insulation

Blanket (Metallized Tedlar AN54W/ 

0.34 PCS Fiberglass)

Calorimeter/

Thermocouple

Tree

(T4, T5, T6

C4, C5, C6)

11.43 cm

Calorimeter/

Thermocouple

Tree

T1, C1

T3, C3

2.54 cm T2, C2

Camera 1

Camera 2

15.24 cm

144.78 cm

13.33 cm

FIGURE 4. INTERMEDIATE-SCALE SETUP WITH IGNITION SOURCE ONLY 

6
Composite 

Ceiling Panel

Fire Ignition Source

(Urethane Foam Block 

Soaked with 

10 cc of Heptane)

0.31 cm from Duct

365.76 cm

313.69 cm

T1, T2, T3

C1, C2, C3

Note:

 T# - Thermocouple

 C# - Calorimeter

 Sensors 2.54 cm apart

Thermoacoustic Insulation

Blanket (Metallized Tedlar AN54W/ 

0.34 PCS Fiberglass)

11.43 cm

T1, C1

T3, C3

T2, C2

Camera 1

Camera 2

15.24 cm

147.32 cm

13.33 cm

B-727 Duct Assembly 

Overhead Air Conditioner

Distribution System

FIGURE 5. INTERMEDIATE-SCALE SETUP WITH AIR CONDITIONING DUCT 

7
FIGURE 6. NARROW-BODY AIRCRAFT AIR CONDITIONING OVERHEAD DUCT 

FIGURE 7. AIR CONDITIONING OVERHEAD DUCT IN AIRCRAFT ATTIC 

8
FIGURE 8. INTERMEDIATE-SCALE SETUP 

FIGURE 9. VERTICAL BUNSEN BURNER POSTTEST 

9
FIGURE 10. INTERMEDIATE-SCALE FIRE TEST 

FIGURE 11. INTERMEDIATE-SCALE TEST TEMPERATURE HISTORY 

10
 

FIGURE 12. INTERMEDIATE-SCALE TEST CALORIMETER HISTORY 

FIGURE 13. POSTTEST CONDITION OF AIR CONDITIONING DUCT 

11
FIGURE 14. HEAT RELEASE TEST RUN 1 

FIGURE 15. HEAT RELEASE TEST RUN 2 

12
FIGURE 16. HEAT RELEASE TEST RUN 3 

FIGURE 17. THE NBS SMOKE TEST RUN 1 

13
FIGURE 18. THE NBS SMOKE TEST RUN 2 

FIGURE 19. THE NBS SMOKE TEST RUN 3 

14
FIGURE 20. THE NBS SMOKE TEST RUN 4 

FIGURE 21. RADIANT HEAT PANEL TEST OF AIR CONDITIONING DUCT MATERIAL 

15
FIGURE 22. RADIANT HEAT PANEL POSTTEST DUCT CONDITION 

16
TABLE 1. TESTS RESULTS 

Test 

No. Test ID Test 1 Test 2 Test 3 Comments 

Vertical Bunsen Burner 

Flame Extinguishing 

Time (sec.) 

0 0 8 sec. Third test specimen sparked 

and had after flame. Allowable 

extinguishing time is 15 sec. 

according to federal aviation 

regulations. 

Burn Length (cm) 6.99 6.99 7.62 Allowable burn length is 20.32 

according to federal aviation 

regulations. 

Drip Extinguishing Time 

(sec.) 

0 0 0 No drips 

1 

Pass or Fail Test? Passed Passed Passed 

Intermediate-Scale Test 

Burn Length (cm) 304.8 304.8 Duct burned completely. Duct 

length was 304.8 cm. 

Heat Release Peak 

(kW/m2

) 

91 63 Ignition source peak heat flux 

was 62 kW/m2

. 

Time to Peak Heat Flux 

(sec.) 

63 66 This time is from ignition to 

heat flux peak. 

Peak Temperature (°C) 825 835 

2 

Pass or Fail Test? Failed Failed FAA goal for improved inflight fire safety is no fire 

propagation. 

Heat Release Test* 

Heat Release Peak 

(kW/m2

) 

74.34 87.86 86.23 Federal aviation regulations 

requires that this value does not 

exceed 65 kW/m2

. 

Heat Release Peak Time 

(sec.) 

12 9 8 

Total Heat Release 

(kW*min/m2

) 

105.11 110.83 119.56 Federal aviation regulations 

requires that this value does not 

exceed 65 kWmin/m2. 

3 

Pass or Fail Test? Failed Failed Failed 

Microscale Combustion 

Calorimeter* 

Fiberglass/

Epoxy 

Laminate 

Urethane 

Foam 

Heat Release Capacity 

(j/g-K) 

123.0 436.0 There is no FAA requirement 

for this test. 

Total Heat Release (kJ/g) 13.4 24.7 

4 

Char (%) 12.6 2.9 

*Note: This test is currently not required by the FAA for ducts or conduits certification. 

17
TABLE 1. TESTS RESULTS (Continued) 

Test 

No. Test ID Test 1 Test 2 Test 3 Comments 

Smoke Test* 

Maximum Specific 

Optical Density (Dm) 

145.02 119.12 127.94 

5 

Pass or Fail? Passed Passed Passed Federal aviation regulations 

requires that this value does not 

exceed 200. 

6 Radiant Panel Heat Test* 

Flame Propagation (cm) Material 

ignited 

very fast; 

test was 

stopped 

before end 

Material 

ignited very 

fast; test was 

stopped 

before end 

N/A Federal aviation regulations 

requires that this value does not 

exceed 5.08 cm. 

Flame Time (sec.) Material 

ignited 

very fast; 

test was 

stopped 

before end 

Material 

ignited very 

fast; test was 

stopped 

before end 

N/A Federal aviation regulations 

requires that this value does not 

exceed 3 sec. 

Pass or Fail? Failed Failed N/A 

*Note: This test is currently not required by the FAA for ducts or conduits certification. 

TABLE 2. HEAT SOURCE PROFILE 

Test 

Peak Heat 

Flux 

(kW/m2

) 

Peak 

Temperature 

(°C) Comments 

Vertical Bunsen Burner 40.6 9.52 Exposure time is 12 seconds 

Intermediate Scale 49.5 781.1 Total heat release calculated for 10 minutes 

Calorimeters on the crown. 

Intermediate Scale 49.5 781.1 Total heat release calculated for 10 minutes 

Calorimeters on the crown. 

Intermediate Scale 62.0 Total heat release calculated for 2 minutes. 

Calorimeters in front of foam. 

Radiant Heat 173.9 - Exposure time is 15 seconds; Just radiant panel 

on—flame was off. 

Heat Release Rate 25.0 - Exposure time is 5 minutes 

Smoke 25.0 - Exposure time is 4 minutes 

Microscale Combustion 

Calorimeter 

- 930.0 

*FAA Minimum Temperature is 843.3°C 

18