A 111 Ob 4 52 b 4 5

NIST

PUBLICATIONS

NBSIR 88-3773

Ignition and Flame Spread

Measurements of Aircraft

Lining Materials

Margaret Harkleroad

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

May 1988

Qnnncnred by:

il Aviation Administration

/OO icaS Center

USL c City, NJ 08405

1713

i fee

c . a—-

75 Years Stimulating America’s Progress

1913-1988

NBSIR 88-3773

IGNITION AND FLAME SPREAD

MEASUREMENTS OF AIRCRAFT

LINING MATERIALS

Margaret Harkleroad

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

May 1988

Sponsored by:

Federal Aviation Administration

Technical Center

Atlantic City, NJ 08405

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

TABLE OF CONTENTS

Page

LIST OF TABLES iv

LIST OF FIGURES v

ABSTRACT 1

INTRODUCTION 2

Purpose 2

Background 2

Objective 3

DISCUSSION 5

Ignition and Lateral Flame Spread Results 5

Apparatus 5

Ignition 5

Flame Spread 7

Flame Height and Flame Heat Transfer on Vertical Walls 10

Apparatus 10

Test Results and Analysis 10

CONCLUSIONS 15

ACKNOWLEDGMENTS 15

REFERENCES 16

NOMENCLATURE 17

iii
LIST OF TABLES

Page

Table 1. Aircraft panel descriptions 4

Table 2. Ignition parameters 7

Table 3. Flame spread parameters in terms of radiant flux 8

Table 4. Lateral flame spread parameters 9

Table 5. Parameters significant toupwarde flame spread 12

Table 6. Upward flame spread parameters 15

IV
LIST OF FIGURES

Page

Figure 1. Schematic of ignition and flame spread apparatus 19

Figure 2. Normalized irradiance over the specimen 19

Figure 3. Correlation of ignition and flame spread results for the

epoxy fiberglass panel 20

Figure 4. Correlation of ignition and flame spread results for the

phenolic fiberglass panel 21

Figure 5. Correlation of ignition and flame spread results for the

epoxy kevlar panel 22

Figure 6. Correlation of ignition and flame spread results for the

phenolic kevlar panel 23

Figure 7. Correlation of ignition and flame spread results for the

phenolic graphite panel 24

Figure 8. Correlation of ignition and flame spread results for the

ABS panel 25

Figure 9. Correlation of ignition and flame spread results for the

polycarbonate panel 26

Figure 10. Correlation of ignition and flame spread results for the

ULTEM panel 27

Figure 11. Equilibrium surface temperatures as a function of external

radiant heating in the test apparatus 28

Figure 12. Schematic of heat transfer apparatus 28

Figure 13. Flame spread problem 29

Figure 14. Procedure for determining average peak burning values 29

Figure 15-A. Flame heat transfer to vertical wall above panel with

epoxy/fiberglass facing 30

Figure 15-B. Flame height from base of burning panel with epoxy/

fiberglass facing 30

Figure 16-A. Flame heat transfer to vertical wall above panel with

phenolic/fiberglass facing 31

Figure 16-B. Flame height from base of burning panel with phenolic/

fiberglass facing 31

v
LIST OF FIGURES (continued)

Page

Figure 17-A. Flame heat transfer to vertical wall above panel with

epoxy/kevlar facing 32

Figure 17-B. Flame height from base of burning panel with epoxy/

kevlar facing . 32

Figure 18-A. Flame heat transfer to vertical wall above panel with

phenolic/kevlar facing 33

Figure 18-B. Flame height from base of burning panel with phenolic/

kevlar facing 33

Figure 1 9-A. Flame heat transfer to vertical wall above panel with

phenolic/graphite facing 34

Figure 19-B. Flame height from base of burning panel with phenolic/

graphite facing 34

Figure 20-A. Flame heat transfer to vertical wall above ABS panel ...... 35

Figure 20-B. Flame height from base of burning ABS panel 35

Figure 21-A. Flame heat transfer to vertical wall above , polycarbonate

panel 36

Figure 21-B. Flame height from base of burning polycarbonate panel 36

Figure 22-A. Flame heat transfer to vertical wall above ULTEM panel .... 37

Figure 22-B. Flame height from base of burning ULTEM panel 37

Figure 23. Wall heat flux distribution for epoxy/fiberglass panel .... 38

Figure 24. Wall heat flux distribution for phenolic/fiberglass panel 39

Figure 25. Wall heat flux distribution for epoxy/kevlar panel ........ 40

Figure 26. Wall heat flux distribution for phenolic/kevlar panel ..... 41

Figure 27. Wall heat flux distribution for phenolic/graphite panel ... 42

Figure 28. Wall heat flux distribution for ABS panel 43

Figure 29. Wall heat flux distribution for polycarbonate panel ....... 44

Figure 3u. Wall heat flux distribution for ULTEM panel 45

Figure 31. Wall heat flux in terms of x/xf 46

vi
LIST OF FIGURES (continued)

Page

Figure 32. Peak energy release rate under external irradiance 47

Figure 33. Peak energy release rate for epoxy/f iberglass panel .*..... 48

Figure 34. Peak energy release rate for phenolic/fiberglass panel .... 49

Figure 35. Peak energy release rate for epoxy/kevlar panel 50

Figure 36. Peak energy release rate for phenolic/kevlar panel 51

Figure 37. Peak energy release rate for phenolic/graphite panel 52

Figure 38. Peak energy release rate for ABS panel 53

Figure 39. Peak energy release rate for polycarbonate panel ..... 54

Figure 40. Peak energy release rate for ULTEM panel 55

vii

Abstract

Experimental tests have been conducted to study the lateral and upward

flame spread behavior of eight aircraft lining materials; three advanced thin

panels (ABS , polycarbonate and ULTEM) and five panels of a honeycomb cell

structure covered with varying facings (epoxy/fiberglass, phenolic/fiberglass,

epoxy/kevlar , phenol ic/kevlar and phenolic/graphite). The state-of-the-art

experimental and analytical procedures are succinctly described in this paper,

but previously they have been expounded fully in the indicated references.

The results have been tabulated in terms of parameters useful in predicting

ignition and flame spread behavior in the presence of an ignition source under

exposure from an external radiant source. Experimental and derived results

are graphically compared. Supplemental ignition, spread, heat transfer and

energy release rate results have been included. Derived material properties

related to and indicative of the propensity to support flame spread are

presented

.

Key words: ignition; flame spread; aircraft interiors; material properties
INTRODUCTION

PURPOSE.

The purpose of this study was to provide the Federal Aviation

Administration (FAA) with information on the flammability of aircraft cabin

interior panel materials.

BACKGROUND.

Experimental data on eight aircraft interior panel materials are to be

derived from measurements made with the flame spread and the heat (energy)

release rate apparatuses at the National Bureau of Standards (NBS). These

results would supplement additional experimental data from FAA on the panels

involving their performances in laboratory, model-scale and full-scale

experiments

.

Post-crash aircraft fire experiments have shown flashover, the event in

which fire growth beyond a localized region of combustion is rapid and extensive, to be the most significant factor affecting survival and escape time.

It is therefore important to understand the flame spread and combustion

characteristics of cabin materials and their role in promoting flashover.

State-of-the-art fire science and technology suggest the feasibility of exper

imentally identifying the mechanics responsible for flashover and relating it

to the contribution of a particular furnishing material. Thus from the obser

vation of fire development and appropriate material data, it is possible to

analyze a particular material in terms of its contribution to flashover. For

- 2

-=
wall and carpet materials, the measurement of their ignition, flame spread

properties, and mass loss and energy release rate should completely characterize their contribution. While predictive methods for fire growth in terms

of laboratory test data are still in the developmental stages, it might be

useful to analyze and correlate full scale results in terras of these data.

Thus, if ignition is assessed to be critical in a specific fire scenario, then

ignition characteristics alone will serve to evaluate a material’s performance. Experiments can then be analyzed to seek clues in developing

correlations with test data.

OBJECTIVE.

The objectives of this study were to examine the performance of selected

aircraft panel materials (5 honeycomb and 3 thin) under piloted ignition as a

function of external radiation for their ignition and flame spread properties.

Parameters relevant to these phenomena were to be derived from experimental

ignition, flame spread and heat transfer data. Since the test procedures and

their theoretical analysis have been fully described by Harkleroad, Quintiere

et al. (references 1, 2, and 3) only the end results are to be presented. For

comparison purposes, results from previous tests (reference 4) of five honeycomb panels with different laminated coverings and additional data taken for

those panels in this series of tests are to be included. The materials are

described in Table 1.

- 3 -
TABLE 1. AIRCRAFT PANEL DESCRIPTIONS*

* Sample Name Description

Epoxy fiberglass Epoxy glass facings, face and back 1 ply 7781 style

woven fiberglass impregnated with epoxy resin, fire

retardant, and co-cured to 1/8 cell Nomax® honeycomb.

One surface to be covered with 2 mil white Tedlar®.

Phenolic fiberglass Phenolic glass facings, face and back 1 ply 7781 type

woven fiberglass impregnated with a modified phenolic

resin, and co-cured to 1/8 Nomex honeycomb. One

surface to be covered with 2 mil white Tedlar.

Epoxy Kevlar® Epoxy Kevlar facings, face and back 1 ply 285 style

woven Kevlar impregnated with epoxy resin fire

retardant, and co-cured to 1/8 cell Nomex honeycomb.

One surface to be covered with 2 mil white Tedlar.

Phenolic Kevlar Phenolic Kevlar facings, face and back 1 ply 285 style

woven kevlar impregnated with a modified phenolic

resin and co-cured to 1/8 cell Nomex honeycomb. One

surface to be covered with 2 mil white Tedlar.

Phenolic graphite Phenolic graphite facings, 1 ply 8 harness satin, 3 K

fiber T-300 woven graphite impregnated with a modified

phenolic resin, and co-cured to 1/8 cell Nomex honeycomb. One surface to be covered with 2 mil white

Tedlar.

ABS A 0.06 inch panel composed of 80% acrylonitrielbutadiene-sy trene and 20% PVC.

Polycarbonate A 0.06 inch polycarbonate of polye ther imide-resin.

ULTEM® A 0.06 inch panel.

The use of trade names are for descriptive purposes only and should not be

construed as endorsement by the National Bureau of Standards or the Federal

Aviation Administration.

-4 -
DISCUSSION

IGNITION AND LATERAL FLAME SPREAD RESULTS ,

APPARATUS . The apparatus for examining radiative ignition and flame

spread is essentially the apparatus developed by Robertson (reference 5). It

consists of a radiant heat source, a sample holder, and a pilot flame to

promote ignition. A schematic of the arrangement is shown in figure 1. A

steel plate is positioned above the sample to extend the sample surface and

enable the boundary layer containing the pyrolized gases and the induced air

flow to be maintained above the sample. An acetylene-air pilot flame interrupts this boundary layer mixture insuring ignition based on the mixture

concentration generated at the sample surface. The radiant heat flux distribution to the sample surface, normalized in terras of incident flux at

x = 50 mm, is shown in figure 2.

IGNITION . Ignition tests were conducted by exposing the panel surface to

an incident flux (q" ) that varied from 1.5 to 6.5 W/ cm" and recording the

time to ignite. A minimum flux necessary for ignition ( q

" . ) is experimentally determined as the limit at which no ignition occurs. The approach

used in the ignition analysis is based on steady-state energy balance which

holds after long heating (references 2, 6) and is represented by the

expression

q o,ig T ) + ea (T

4 - T4

) = h

s' ig s'

( 1 )
where T- represents the ignition temperature, T the ambient temperature, h

-Lg S C

the convective heat transfer coefficient, a the surface absorbency and £ the

eraissivity.

The ignition time (t), for the cases in which the incident flux is great

enough to ignite the material, is correlated in terms of

F(t)

b/t, t < t - ra

1, t > t — m

( 2 )

where F(t) is a time-response function representing the thermal response of

the material to external radiation, b is a material constant and t is a

m

characteristic time indicative of the thermal equilibrium time (references 2,

6). The ignition data with the correlated results indicated by the solid line

are shown in figures 3-10. Quintiere (reference 2) has shown that the

parameter b can be used to compute an effective material kpc from the

expression

kpc = 4/tt (h/b) 2 ! (3)

where h, a heat transfer coefficient, is determined at the ignition

temperature (T. ). Ignition temperatures (T. ) can be found from the

^5 ^"5 theoretical curve of figure 11 which expresses the surface temperature of a

material, under long heating conditions in the apparatus, as a function of

external radiant flux (reference 2, 6, 8). Ignition parameters for the three

thin and the five honeycomb panels are listed in Table 2.

- 6 -

Page: 25

Nelson, H. E.

Snell, J. E.; Nelson, H. E.

Summary of the National Bureau of Standards' Analysis of the

Dupont plaza Hotel Fire.

fire investigations; hotels

Ohlemiller, T.

Ohlemiller, T. ; Shaub, W.

Products of Wood Smolder and Their Relation to Wood-Burning

Stoves

.

wood; combustion products; smoke; smoldering combustion; air

pollution; wood stoves

Ohlemiller, T. J.

Gann, R. G. ; Harris, R. H. , Jr.; Krasny, J. F. ; Levine, R.

S.; Mitler, H. E.; Ohlemiller, T. J.

Effect of Cigarette Characteristics on the Ignition of Soft

Furnishings. Volume 3. Technical Study Group Cigarette

Safety Act of 1984.

cigarettes

Olson, S.

Olson, F

„

Flame Spread Over a Thin Fuel in Microgravity. CFR Video

Seminar.

reduced gravity; flame spread; solid fuels; diffusion flames

Paabo, M.

Babrauskas, V.; Harris, R. H. , Jr.; Gann, R. G. ; Levin, B.

C. ; Lee, B. T. ; Peacock, R. D. ; Paabo, M. ; Twilley, W.

;

Yoklavich, M. F. ; Clark, H. M.

Comparative Fire Hazards of Fire-Retardant Treated and

Non-Retarded Products.

flame retardants; plastics; fire hazards; fire tests

Babrauskas, V.; Harris, R. H. , Jr.; Gann, R. G. ; Levin, B.

C. ; Lee, B. T. ; Peacock, R. D. ; Paabo, M. ; Twilley, W. ; Yoklavich, M. F. ; Clark, H. M.

Fire Hazard Comparison of Fire-Retarded and

Non-Fire-Retarded Products.

flame retardants; cone calorimeters; furniture calorimeters;

chromatography; plastics; heat release rate; compartment

fires; fire tests; smoke production

Levin, B. C. ; Paabo, M. ; Gurman, J. L. ; Clark, H. M.

;

Yoklavich, M. F.
TABLE 2. IGNITION PARAMETERS

kpc

Aircraft Panel

• • q °» i|

(W/ cm'

T •ig

(°C)

b

(s- 1/2

)

t m

(s) (

k

\m2

K y/

ABS 1.6 388. 0.073 188. 0.76

epoxy /f i berg lass 2.0 438. 0.132 58. 0.174

epoxy/kevlar 2.3 465. 0.135 55. 0.188

polycarbonate 2.9 518. 0.072 190. 0.84

phenolic/kevlar 3.4 558. 0.196 26. 0.133

phenolic/ fiberglass 3.6 570. 0.227 19. 0.107

phenolic/graphite 3.6 570. 0.72 34. 0.186

ULTEM 3.8 585. 0.08 156. 0.91

FLAME SPREAD. Opposed flow spread results were, obtained fromi tests

conducted with the panel (mounted as indicated in figure 1) exposed to a known

external radiant flux (q"

e

). :Ignited by a pilot flame and noting the lateral

flame spread position (x

p

) as a function of time (t). These flame spread

results are applicable to opposed flow flame spread on a vertical surface

where the flame provides a constant heat flux that influences the opposed flow

(reference 1). The spread velocity (V) is expressed in terms of the external

radiant flux (q" ) from the flux distribution curve of figure 2 and time (t).

dx

(x (t)).

P

(4)

It has been shown (references 1, 2, 6) that flame spread for a material under

thermal equilibrium can be correlated by the expression

o, s < q" F (t) < q 0,lg = C [ q ''o,ig q

"e F(t) l

; for q

" (5)
where C is a material flame heat transfer factor, q" . j. s the minimum flux

necessary for ignition, F(t) is the time response factor and q"

0 s is the

maximum flux necessary for spread derived from the flame propagation limit.

Equation 5 is valid when the minimum flux required to propagate spread ( q

" ) U j u

is greater than the product of the externally applied flux (q”

e ) and the time

function f(t), and this product is greater than the minimum flux necessary for

ignition. A minimum flux for flame spread, q" can be derived from the U <J u flame propagation limit and figure 2 (reference 1). The measured spread

velocities, with the correlated results indicated by the dashed line are shown

in figures 3-8 for the condition where the material is under an external

irradiance a sufficient time to reach thermal equilibrium. While spot

ignition was observed at protruding surfaces, insufficient spread occurred

overall to calculate accurate flame spread results for the polycarbonate and

ULTEM panels. The polycarbonate panel melted forming various shapes and sizes

and pulled away from the holder. The ULTEM bubbled, melted, and charred.

Flame spread parameters in terms of radiant flux are listed in Table 3.

TABLE 3. FLAME SPREAD PARAMETERS IN TERMS OF RADIANT FLUX

• c q o, ig

/ „

c

a /2 ,,2 X

10 ^ o , s Aircraft Panel (W/ cm2

) (—\ mm ) ( cm \

V w /

(W/ cm'

ABS 1.9 1.9 0.93

epoxy /fiber glass 2.1 2.5 1.90

epoxy/kevlar 2.4 1.20 1.70

polycarbonate NS NS NS

phenol ic/kevlar 3.5 1.16 2.8

phenolic/ graphite 3.7 0.97 2.8

phenolic/ fiberglass 3.8 0.63 2.6

ULTEM NS NS NS

NS indicates no flame spread

8 -
Flame spread can also be represented by the expression

$

2

kpc (T. - T ) ig s'

for T < T < T.

s ,m - s - ig ( 6 )

where $ is an empirical parameter representing the gas phase properties, flame

temperature, opposed flow gas velocity and chemical kinetic effects usually

denoted a Damkohler number (reference 2). The related flame spread parameters

are tabulated in Table 4. Here T^g is derived from the sample’s ignition

data, that is, from Table 2.

TABLE 4. LATERAL FLAME SPREAD PARAMETERS

kpc $

T.ig (“ f-(kW)

2

Q

T

s ,min

Aircraft Panel (°C) \m2K/

J

m (°C)

ABS 388. 0.76 6.63 282.

epoxy/ fiberglass 438. 0.174 1.17 425.

epoxy/kevlar 465. 0.188 4.86 400.

polycarbonate 518. 0.84 NS 518.

phenolic/kevlar 558. 0.133 2.47 510.

phenolic/ fiberglass 570. 0.107 6.23 490.

phenolic/ graphite 570. 0.186 4.58 510.

ULTEM 585. 0.91 NS 585.

NS indicates no flame spread

The flame spread "properties" listed in Table 3 depend on the

apparatus/environmental conditions. Those listed in Table 4 are correlation

parameters defined from the flame spread model. They are more generic

properties and approximate the underlying physical-chemical properties. In

both cases, these properties have been determined under natural convection

conditions in normal air. For other conditions at least the $ parameter would

- 9 -
change -- for example, it depends on the gas velocity and ambient oxygen

concentration.

FLAME HEIGHT AND FLAME HEAT TRANSFER ON VERTICAL WALLS

APPARATUS . Flame height and flame heat transfer tests were conducted

with a sample flush-mounted below a water-cooled instrumented copper plate,

2 exposed to an external irradiant flux (q"

e

) that varied from 1 to 4 W/cm , and

ignited with a line burner positioned below the sample. A schematic of the

apparatus is shown in figure 12. Total heat flux (q" ) was recorded by water

cooled heat flux sensors embedded in the copper plate at six locations above

the sample. The flame heat flux (q"^) was determined by subtracting the

recorded external radiant flux. Flame heights (x^), defined as the uppermost

position of the luminous flame, were determined from video records.

TEST RESULTS AND ANALYSIS . Figure 13 schematically depicts the approach

used in analyzing the flame spread problem. Here, the region over which

pyrolysis has ceased is indicated by x^ and the time for this burnout, i.e.,

the duration of the pyrolysis, by t^. The pyrolysis height, i.e., the region

undergoing pyrolysis is represented by x

p

, the flame height by x

f

, and the

time for spread over the flame heat transfer region by t^.

Peak burning values were obtained by an arbitarily selected data

averaging procedure shown in figure 14 for the heat flux vs time curve of the

O epoxy kevlar panel under an external irradiance of 3 W/cm . Average peak heat

fluxes and flame heights were determined for the time period representing 80

percent of the maximum values recorded. Similarly, the time that bounds 10

-10 -
percent of the peak flux defines the burn time (t^). This burn time will

change as the material thickness changes.

The approach used for expressing upward flame spread velocity on a

vertical surface is from reference 3 and is represented as

(7)

or

( 8 )

where q"f represents the flame heat flux; Xf the flame height; Xp the

pyrolysis height, T. and T the ignition and surface temperatures,

lg s respectively; kpc the material thermal property; and t^ the time for spread

over the flame heat transfer region (x^ - Xp) where

t

f kpc [ hig - T

s )/qf]

2

- (9)

While an understanding of upward spread behavior is incomplete, these

results suggest some tendencies for evaluating the problem. In evaluating the

condition necessary for sustained propagation, the ratio of tf/t^ may be

significant since the burning time, t^, must be long relative to tf in order

for spread to occur. Nominal spread rates computed from eq . 8 are similar in

magnitude to the opposed flow maximum spread rate in figures 3-10. A summary

of the results for upward spread are included in Table 5. Scatter in the

flame heat flux data for the honeycomb panels is indicative of the random

- 11 -
TABLE 5. PARAMETERS SIGNIFICANT TO UPWARD FLAME SPREAD

Flame Nominal

80% 80% Heat Spread

External F lame Flame Spread Burn Transfer Rate

,

Flux Flux Length Time Time Length (Eq. (8))

d x (q"

e

) (q"

e

) (x

f

) (t

f

) < b b> (x f-y V - —£

dt

( W/ cm^) (W/ cm^

)

(cm) ( 8 ) (s) (cm) (mm/8)

epoxy 2.0 1.1 48. 249. 80. 20. 0.8

fiberglass 1 2.5 1.3 58. 178. 100. 30. 1 .7 3.0a 2.6 NV 45 88. NV NV 3.1 2.2 60. 62 80. 32. 5.2

3.4 a 2.0 48. 75. 60. 20. 2.7

3.5 2.4 52. 52. 25. 24. 4.6

3.8 a 0.9 61. 372. > 29. 33. 0.9

phenolic 2.5 1.6 38. 124. 25. 10. 0.8

fiberglass 3.0 1.9 66. 88. 25. 38. 4.3

3.4 1 .6 56. 124. 55. 28. 2.3

3.5 2.0 60. 80. 75. 32. 4.0

3.8 d 0.8 90. 497 . 43. 62. 1.2

epoxy 2.0 1 .6 66. 144. 115. 38. 2.6

kevlar 2.0 2.0 49. 92. 135. 21

.

2.3

2.5 1.1 48. 305. 1 15. 20. 0.6

3.0 e 0.9 57. 455. 115. 29. 0.6

3.0 2.1 45. 84. 75. 17. 2.0

3.3 2.0 50. 92. 77. 22. . 2.4

3.4 1 .8 48. 114. 75. 20. 1 .8 3.7 1.7 89. 128. 101 . 61 . 4.8

3.8 1 .6 64. 144. 115. 36. 2.5

phenolic 2.5 1.6 54. 149. 364 . 26. 1 .7 kevlar 3.0 2.1 54. 87. 30. 26. 3.0

3.0 b

1 .4 66. 195. 28. 38. 1.9

3.4 2.0 100. 96. 68. 72. 7.5

3.6 4.3 58. 21. 66. 30. 14.3

3.7 b 2.7 61. 52. 101

.

33. 6.3

phenolic 2.0 1.0 40. 556 . 29. 12. 0.2

graphite 2.5 2.1 42. 126. OO LO • 14. 1.1

3.0 b

1 .1 53. 459. 29. 25. 0.5

3.0 2.1 55. 126. 96. 27. 2.1

3 .4 a

1 .5 55. 126. 96. 27. 2.1

3.4 2.1 63. 121. 75. 25. 2.1

3 . 7 C

1 ,0 66 e 556. 29. 38. 0.7

ABS 2.6 3.6 89. 79. 96. 61. 7 .7 3.1 3.4 102. 88. 96. 74. 8.4

3.3 3.2 95. 99. 96. 67. 6.8

polycarbonate 2.6 1 .4 49. 1054. 63. 21

.

0.2

3.0 2.5 63. 331. 124. 35. 1 .1 3.4 1.8 60. 638. 83. 32. 0.5

ULTEM 2.6 1.0 34. 2844. 39. 6. 0.02

3.1 1.1 42. 2350. 204. 14. 0.06

3.4 0.7 39. 5803. 55. 11. 0.02

NV indicates no video

a facing peels upward covering lower sensor

'’part of facing fell from sample

'facing exploded, burning only at edges

^burning limited to lower edge of panel

? burning extinguished and then re-ignited

-12 -
unravelling process of the facing when heated. The heat transferred to the

flux sensors was dictated by the decomposition of the facing which was

observed to unravel upward and cover the lower sensor, unravel to the side

directing the hot gases away from the sensors and to disintegrate with some

sections falling away from the sample. Scatter in the flame heat flux data of

the thin panels is indicative of their melting and dripping behavior.

Typical measured flame heat flux results are shown in figures 16-22,

series A, for the panels under an external irradiance of 3 W/cm. Figures

16-22, series B, show corresponding measured flame heights. The data are

analyzed in terms of the wall heat flux distributions shown in figures 23-30.

The panels showed a decreasing flux distribution with distance measured from

the base of the fire (bottom scale). This distance is normalized with the

flame height (top scale) and the data are replotted in those figures as an

attempt to coalesce the results into a general correlation. The solid line

indicates Hasemi’s data from reference 3 for a correlation of gaseous fuel

heat transfer results along walls. Data for the eight panels are collectively

shown in figure 31. For the most part, the data tend to group around the

curve representing Hasemi’s data.

Energy release rates (E"), based on flame height were derived from the

expression

x

f = k

f

(E'*)

2//3

. (10)

from references 3 and 10. Here E" is the energy release rate per unit flame

2/3 width and is the experimentally derived constant (0.0569 m/(kW/m) ) from

Hasemi's CH^ line burner data. A comparison of the peak energy release rate

-13 -
for the panels at varying external irradiances is shown in figure 32. The

curves represent a least square fit of the data shown in figures 33-40. The

solid portion of the line indicates the range for which ignition would be

expected to occur based on the results of Table 2. (Lower values for the

critical heat flux for ignition than shown in Table 2 are probably due to

orientation differences and the bottom pilot flame in the vertical heat

transfer apparatus).

A propagation parameter (y) indicative of flame spread capability can be

expressed in terms of energy release rate (E"), flame temperature (t^) and

burn time (t^); Quintiere (reference 3), Williams (reference 10). This

propagation parameter (y) is derived from the expression

y = aE'

f - t / 1 - 1 (11)

f b

from the work of Quintiere and

y = aE" t /2t - 2 /tt ' (12)

b f

from the work of Williams. These theoretical results suggest that sustained

flame spread propagation will occur for values of y > 0.

Measured and derived flame spread parameters are listed in Table 6 for a

nominally fixed irradiance of 3 W/cm .

-14 -
TABLE 6. UPWARD FLAME SPREAD PARAMETERS

q’e t

f

+

tb E" u u Aircraft Panel (W/cm2

) (s) (s) (kW/m2

) Eq. (11) Eq. (12)

ABS 3.1 127. 96. 285. 0.52 0.62

epoxy fiberglass 3.0 38. 88. 140. - 0.03 0.37

epoxy kevlar 3.0 46

.

77. 140. - 0.20 0.15

polycarbonate 3.0 258. 124. 190. - 1.18 - 0.20

phenolic kevlar 3.0* 48. 30. 140. - 1.2 - 0.35

phenolic fiberglass 3.0* 40. 25. 140. - 1.2 - 0.35

phenolic graphite 3.0* 70. 27. 140. - 2.19 - 0.51

ULTEM 3.1* 372. 204. 55. - 2.27 - 0.84

* critical ignition flux not exceeded

+ calculated for q"f = 25 kW/ m , see Eq

.

(9)

CONCLUSION

Results useful in the prediction of opposed flow flame spread on vertical

surfaces are tabulated in Tables 2, 3, and 4 for the eight aircraft lining

materials studied. Parameters indicative of their propensity for and

properties related to upward flame spread are shown in Tables 5 and 6. Some

of these data relate to bulk properties associated with the particular

material tested and correspond to the theoretical correlating models for flame

spread. Other data presented, such as flame height and flame heat flux,

depend on the scale of the experiment and the fire dynamics in general.

ACKNOWLEDGMENTS

The author is indebted to Dr.. J. Quintiere for his technical assistance

and guidance in the data analysis and to B. Rinkinen and D. Wagger for their

assistance in conducting the experimental tests.

-15 -
REFERENCES

1. Harkleroad, M. , Quintiere, J. and Walton, W. , "Radiative Ignition and

Opposed Flow Flame Spread Measurements on Materials", U.S. Department of

Transportation, Fed. Aviation Admin. Tech. Ctr., DOT/FAA/CT83/28

,

August 1983.

2. Quintiere, J. and Harkleroad, M., "New Concepts for Measuring Flame

Spread", Symp. on Applications of Fire Science to Fire Engineering, Amer.

Soc. Testing and Materials/Soc . Fire Prot. Engrs.', Denver, CO,

June 26-27, 1984.

3. Quintiere, J., Harkleroad, M. and Haserai, J., "Wall Flames and

Implications for Upward Flame Spread", AIAA Paper No. 85-0456, 1985.

4. Quintiere, J., Babrauskas, V., Cooper, L., Harkleroad, M., Steckler, K.

and Tewarson, A., "The Role of Aircraft Panel Materials in Cabin Fires

and Their Properties", U.S. Dept. Trans., Fed. Aviation Admin. Tech.

Ctr., DOT/FAA/ CT-84-30 , 1985.

5. Robertson, A.F., "A Flammability Test Based on Proposed ISO Spread of

Flame Test", Third Progress Report, Intergovernmental Maritime

Consultative Organization, IMCO FP/215, 1979.

6. Quintiere, J., Fire and Materials, Vol. 5, No. 2, 1981, pp. 52-60.

7. Babrauskas, V., "Development of the Cone Calorimeter - A Bench Scale Heat

Release Rate Apparatus Panel on Oxygen Consumption", Nat. Bur. Stand.,

NBSIR 82-2611, November 1982.

8. Quintiere, J., Harkleroad, M. and Walton, D., Comb. Sci. and Technol.,

1983, Vol. 32.

9. Sibulkin, M. and Kim, J., Comb. Sci. and Technol ., 1977, Vol. 17.

pp. 39-49.

10.

Saito, K., Williams, F.A. and Quintiere, J., "Upward Turbulent Flames",

International Symposium on Fire Safety Science, 1985.

- 16 -
NOMENCLATURE

b

c

C

E"

F(t)

h

h

c

k

kf

q "e

• B ^ f

q o,ig

^"o,s

t

c b

T

ig

T

s

T

s ,m

V

x

f

X

P

X

P

P

parameter in eq . (2)

specific heat

parameter in eq . (5)

energy release rate per unit flame width

thermal time-response function

heat loss coefficient

convective heat transfer coefficient

thermal conductivity

constant in eq . (10)

external radiant flux

flame heat flux

critical flux of ignition

critical flux for spread

time

pyrolysis burn time

time for spread over heat transfer region

characteristics equilibrium time

ignition temperature

surface temperature before flame effects

minimum temperature for spread

flame velocity

flame height

lateral flame position in eq . (4)

pyrolysis height in eqs. (7, 8)

density

- 17 -
emissivi ty

a

$

U

Stef an-Boltzmann constant

parameter in eq . (6)

parameter in eqs. (11, 12)

-18
APPARATUS

Figure 1 . Schematic of ignition and flame spread apparatus.

0 200 400 600 800

x, DISTANCE ON SPECIMEN |mm|

Figure 2 . Normalized irradiance over the specimen.

- 19 -
SPREAD

RATE

(

mm/

)s

CD

Figure 3. Correlation of ignition and flame spread results for the

epoxy fiberglass panel.

20

50.0

100.0

150.0

200.0

250.0

300.0

350.0

“

100.0

TIME

TO

IGNITE(s)
SPREAD

RRTE

(

mm/s )

4.0

5.0

6.0

7.0

8.0

o

O -1 a

I ” i— 1 r— r— ~i r 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

IRRflDIRNCE(N/cm2

)

Figure 4. Correlation of ignition and flame spread results for the

phenolic fiberglass panel.

21
SPREAD

RATE

(

mm/

)s

o

IRRflDIANCE(N/cm2

)

Figure 5. Correlation of ignition and flame spread results for the

epoxy kevlar panel.

22

50.0

.

100.0

150.0

•

200.0

250.0

300.0

350.0

400.0

TIME

TO

IGNITE(s)
SPREAD

RRTE

(

mm/

)s

O o

1

i I

^ r

: r~

O.Q 1.0 2.0 3.0 4.0 5.0 6.0 7.0

IRRRDIflNCE (W/cm2)

Figure 6. Correlation of ignition and flame spread results for the

phenolic kevlar panel.

23
SPRERQ

RATE

(

rnm/s

)

Figure 7. Correlation of ignition and flame spread results for th

phenoloc graphite panel.

24

50.0

100.0

150.0

200.0

250.0

300.0

350.0

-100.0

TIME

TO

IGNITE(s)
SPREAD

RATE

(

mm/s )

0-0

1.0

2.0

3.0

4.0

5.0

6.0

7,0

8.0

9.0

10.0

o

o

0.0 8.0

IRRRDIRNCE ( N/cm 1

Figure 8. Correlation of ignition and flame spread results for the

ABS panel

.

25

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

TIME

TO

IGNITE(s)
SPREAD

RATE

(

mm/

s

1

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

IRRADIANCE f W/cm2)

Figure 9 . Correlation of ignition and flame spread results for the

polycarbonate panel.

26

100.0

200.0

30J.0

400.0

600.0

600.0

700.0

800.0

900.0

TIME

TO

IGNITE(s)
SPRERD

RRTE

(

mm/

)s

o

o -1

o

CD

O

CO ~

O

o

cc

o

LO

o

TT

o

ro “

O

r\j "

O

O

i — i 0.0 1.0

o

2.0

i i

’

' i 3.0 4.0 5.0

IRRRDIRNCG( W/cm2)

6.0 7.0

o

o

3.0

Figure 10. Correlation of ignition and flame spread results for the

ULTEM panel.

27

100.0

200.0

300.0

400.0

000.0

600.0

TIME

TO

IGNITE!

si
APPARATUS CALIBRATION CURVE

Figure 11. Equilibrium surface temperatures as a function of external

radiant heating in the test apparatus.

Cooled copper plate

(1.27 cm x 25 m)

TC (embedded in panel back - 6 )

Cooled side panel

(17 cm)

Radiative heat flux sensor (3)

Total heat flux sensor (6)

Sample

(28.4 cm x 28.4 cm)

Pilot flame

(height 2.5 cm)

Figure 12. Schematic of heat transfer apparatus.

- 28 -
Figure 13, Flame spread problem.

Figure 14. Procedure for determining average peak burning values.

-29
o 30 60 90 120 150

TIME (s)

Figure 15-A. Flame heat transfer to vertical wall above panel with

epoxy/fiberglass facing.

Figure 15-B. Flame height from base of burning panel with epoxy/fi bergl ass facing.

- 30 -
Figure 16-A. Flame heat transfer to vertical wall above panel with

phenolic/fiberglass facing,

Figure 16-B. Flame height from base of burning panel with phenolic/

fiberglass facing.
/

Figure 17-A. Flame heat transfer to vertical wall above panel with

epoxy/ kevlar facing.

Figure 17-B. Flame height from base of burning panel with epoxy/kevlar facing.

- 32 -
0 30 60 90 120 150

TIME (s)

Figure 18-A. Flame heat transfer to vertical wall above panel with

phenol ic/kevl ar facing.

Figure 18-B. Flame height from base of burning panel with phenol ic/kevlar facing.
0 40 80 120 160 200

TIME (s)

Figure 19-A. Flame heat transfer to vertical wall above panel with

phenolic/graphite facing.

Figure 19-B, Flame height from base of burning panel with phenolic/graphite facing.
X

3

I-<

LUX

UJ2

<

0 40 80 120 160 200

TIME (s)

Figure 20-A. Flame heat transfer to vertical wall above ABS panel

Figure 20-B. Flame height from base of burning ABS panel.
Figure 21 -A. Flame heat transfer to vertical wall above polycarbonate panel

Figure 21-B. Flame height from base of burning polycarbonate panel.
Figure 22-A. Flame heat transfer to vertical wall above ULTEM panel

Figure 22- B . Flame height from base of burning ULTEM panel.

- 37 -
(3

ujo/m)

10

x/Xf

0.1 1.0

x (cm)

Figure 23. Wall heat flux distribution for epoxy/fiberglass panel.

38
(

s

wo//\a)

X/Xf

0.1 1.0 10

Figure 24. Wall heat flux distribution for phenolic/fiberglass panel.

39
(W/cm

2)

X/Xf

0.1 1.0 10

x (cm)

Figure 25. Wall heat flux distribution for epoxy/kevlar panel.

40
(

3

ujo/m)

M

b

X/Xf

0.1 1.0 10

x (cm)

Figure 26. Wall heat flux distribution for phenolic/kevlar panel.

41
(W/cm^)

x/xf

0.1 1.0 10

Figure 27. Wall heat flux distribution for phenolic/graphite panel.

42

t>A
(W/cm

2)

0.1

x/x

f

1.0 10

x(cm)

Figure 28. Wall heat flux distribution for ABS panel.

43

O

<1
(W/cm

2)

x/x f

1 10 100

x(cm)

Figure 29. Wall heat flux distribution for polycarbonate panel.

44
(W/cm

2)

0.1

x/x

f

1.0 10

x(cm)

Figure 30. Wall heat flux distribution for ULTEM panel.

45
qf

(W/cm

2)

10

1.0

0.1

0.01

i—

r

TT

Hasemi data

T I I I I I I I

| O Epoxy fiberglass

V Phenolic fiberglass

Epoxy kevlar

A Phenolic kevlar

O Phenolic graphite

< ULTEM

> Polycarbonate

o ABS

0.1 1.0

X/Xf

10

Figure 31. Wall heat flux in terms of x/x

f

.

46
700

o O o o o o o

o O o o o o

CD LO ''t CO C\J T—

(sW/M>D V3dV

-LIND U3d 31VU 3SV313H A0H3N3 >IV3d

CMco

<DU

3

to

•H

47

EXTERNAL

IRRADIANCE

(W/cm

2)
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m2)

300

200

100

0

Figure 33.

1 I 1 1 1 1—1 1 1

— V

V

A

A

A

V

O o

o

O

o o

#1 EPOXY FIBERGLASS

O Flame heat transfer - vertical

FMRC combustibility - horizontal

A Cone calorimeter (peak) - horizontal

VCone calorimeter (peak) - vertical

i I i l i I l l J

01 23456789 10

EXTERNAL IRRADIANCE (W/cm2)

Peak energy release rate for epoxy/fiberglass panel.

48
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m

2)

300

200

100

0

01 23456 789 10

EXTERNAL IRRADIANCE (W/cm 2

)

Figure 34. Peak energy release rate for phenolic/f iberglass panel.

#2 PHENOLIC FIBERGLASS

o Flame heat transfer - vertical

FMPC combustibility - horizontal

A Cone calorimeter (peak) - horizontal

V Cone calorimeter (peak) - vertical

o

o

V

A

49
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m

2)

300

200

100 -

0

1 1 1 1 1

1 1 1 1 #3 EPOXY KEVLAR

O Flame heat transfer - vertical

FMRC combustibility - horizontal

A Cone calorimeter (peak) - horizontal

V Cone calorimeter (peak) - Vertical

O

V

A

o ~ v o

v

A

§° — £a

°0 %

0

i i i i i i 1 1 1 01 23456789 10

EXTERNAL IRRADIANCE (W/cm 2

)

Figure 35. Peak energy release rate for epoxy/kevlar panel.
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m

2)

300

100

v

o

A

O

O

O

8

°

#4 PHENOLIC KEVLAR

o Flame heat transfer - vertical

FMRC combustibility - horizontal

A Cone calorimeter (peak) - horizontal

V Cone calorimeter (peak) - vertical

I I I 01 23456 789 10

EXTERNAL IRRADIANCE (W/cm 2

)

Figure 36. Peak energy release rate for phenolic/kevlar panel.

51
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m

2)

300

200

100

0

Figure

i i i i i i—n 1 1

#5 PHENOLIC GRAPHITE

o Flame heat transfer - vertical

FMRC combustibility - horizontal

A Cone calorimeter (peak) - horizontal

V Cone calorimeter (peak) - vertical

A

A

D V

V

(P

o

8

°

i i i i i i i I— i i 01 23456789 10

EXTERNAL IRRADIANCE (W/cm 2

)

Peak energy release rate for phenolic/graphite panel.

52
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m

2)

i

500

400

300

200

100

- 0

A

o

o

o

ABS

O Flame heat transfer - vertical

Cone calorimeter (peak) -

horizontal

A Cone calorimeter - vertical

01 234 56 789 10

EXTERNAL IRRADIANCE (W/cm 2

)

Figure 38. Peak energy release rate for ABS panel.

53
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m

2)

600 -

500 -

400 -

300 -

200 ”

100

i r

o

"i r i r

O

° POLYCARBONATE

O Flame heat transfer - vertical

Cone calorimeter (peak) - horizontal

A Cone calorimeter - vertical

0 1 23456789 10

EXTERNAL IRRADIANCE (W/cm 2

)

Figure 39. Peak energy release rate for polycarbonate panel.

54
PEAK

ENERGY

RELEASE

RATE

PER

UNIT

AREA

(kW/m

2)

300

200

100

ULTEM

O Flame heat transfer - vertical

Cone calorimeter (peak) - horizontal

A Cone calorimeter - vertical

o

0 E

A

01 23456 789 10

EXTERNAL IRRADIANCE (W/cm2

)

Figure 40. Peak energy release rate for ULTEM panel.

55
FORM NBS-1 14A (REV. 11-84)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. Publ ication Date

NBSIR 88-3773 May 1988 4.

TITLE AND SUBTITLE

Ignition and Flame Spread Measurements of Aircraft Lining Materials 5.

AUTHOR(S)

Margaret Harkleroad

6.

PERFORMING ORGANIZATION (If joint or other than N BS, see in struct ion s)

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

7. Contract/Grant No.

8 . Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City . State , ZIP)

Federal Aviation Administration

Technical Center

Atlantic City, NJ 08405

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information , If document includes a significant

bi bliography or literature survey , mention it here)

Experimental tests were conducted to study the lateral and upward flame spread

behavior of eight aircraft lining materials . The results are tabulated in terms of

parameters useful in predicting ignition and flame spread in the presence of an

ignition source under exposure to an external radiant source. Experimental and

derived results are graphically compared. Derived material properties related to

and indicative of the propersity to support flame spread are presented.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) ignition; flame spread; aircraft interiors; material properties

13. AVAILABILITY

^X! Unl imited ^ or Official Distribution. Do Not Release to NTIS

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