NBSIR 73-125

Interlaboratory Evaluation of the

Tunnel Test (ASTM E 84] Applied to

Floor Coverings

T. G. Lee and Clayton Huggett

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

March 1973

Final Report

Prepared for Social Security Administration

Health Services & Mental Health Administration

Department of Health, Education, & Welfare

Washington. D. C. 20201

NBSIR 73-125

INTERLABORATORY EVALUATION OF THE

TUNNEL TEST (ASTM E 84) APPLIED TO

FLOOR COVERINGS

T. G. Lee and Clayton Huggett

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

March 1973

Final Report

Prepared for: Social Security Administration

Health Services & Mental Health Administration

Department of Health, Education, & Welfare

Washington, D. C. 20201

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

IMATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

Table of Contents

Page

Abstract 1

1. Introduction 2

2. The ASTM E 84-70 Test Method 3

3. Interlaboratory Evaluation of Test Method 5

3.1 Participants 6

3.2 Test Materials ..... 9

3.3 Experimental Design 11

4. Survey Results 13

4.1 Physical Characteristics of Furnaces 13

4.1.1 Furnace Windows 13

4.1.2 Location of Manometer and Photometer 14

4.1.3 Draft Control 14

4.1.4 Furnace Air Velocity and Temperature 15

4.1.5 Thermocouple Type and Mounting 16

4.1.6 Relative Humidity of Intake Air 16

4.2 Illustration of Furnace Characteristics 17

5. Results of Tests 23

5.1 Statistical Results . . . . o 29

5.2 The Use of Other Formulas for FSC Calculation 31

6. Discussion 33

6.1 Tunnel Construction Variables 33

6.2 Results of Flame Spread Measurement 37

6.3 Effect of Using Single Formulas for FSC Calculation ... 39

7. Conclusions. . . , , 43

8. Recommendations 44

lii
9, Acknowledgement 46

Appendix A. Sample Data Sheet 47

Appendix B. Dimensions of ASTM E 84 Furnace 48

Appendix C. Task Groups Under ASTM E5.04 to Study Revision of

E 84 Standard 49

Appendix D. Method of FSC Calculation, Current E 84-70 Standard ... 50

Appendix E. Calculation of Reproducibility 51

References 52

List of Illustrations

1. Representative E84 Tunnels 17

2. Representative E84 Tunnels 18

3. Examples of Smoke Meter Locations 19

4. Examples of Thermocouple Mountings 20

5. Examples of Windows and Bricks 21

6. Examples of Burners 22

7. Mean FSC of Each Lab versus Mean of All Labs 24

8. FSC as Function of Density for Material #3 40

9. Distance-Time Plot of Typical Test for Nine Materials 42

List of Tables

1. Participants in the Interlaboratory Evaluation 7

2. Test Materials 8

3. Survey Results on Selected Characteristics 12

4. Data on Flame Spread (FSC) 25

5. Data on Smoke 26

6. Data on Fuel Contribution 27

iv
Interlaboratory Evaluation of the Tunnel Test

(ASTM E 84) Applied to Floor Coverings

T. G. Lee and Clayton Huggett

Results of an interlaboratory evaluation of the ASTM

E 8A tunnel test method involving eleven laboratories and

nine materials, including four carpets, are reported. Data

on flame spread, smoke, and fuel contribution are analyzed

statistically. Selected physical characteristics of each

tunnel are tabulated and compared relative to specifications in the test method. The between-lab oratory

coefficient of variation (reproducibility) in flame spread

classification (FSC) was found to range from 7 to 29% for

the four carpets and from 18 to 43% for the other materials

tested. The between-laboratory coefficients of variation

for smoke developed and fuel contribution ranged from 34 to

85% and from 22 to 117% respectively for all materials tested.

The causes of higher variability in smoke and fuel contribution measurement between laboratories is not definitely

known but may reasonably be attributed to variations in

tunnel construction, maintenance, and operation, in the

location of photometers, and in the mounting of thermocouples in different laboratories. Some variability of

results may possibly be due to variation in test specimens.

Variation in construction and measurement techniques among

tunnels may be minimized by updating the test method

"standard.

Key words: ASTM E84; building materials; carpets; fire

tests; flame spread tests; interlaboratory evaluation;

round-robin; statistical analysis; test method standard.

1
1. Introduction

Practically all building code requirements in the United States

for control of the flamability of interior surface finish materials are

based on the ASTM E 84-70 [1]* twenty-five foot tunnel test method, also

used in UL 723, NFPA No. 255-1972 and ANSI A2. 5-1970. The reproducibility

and appropriateness of the method have not been seriously questioned in

the past because the tests were conducted by only two or three laboratories and limited to traditional construction materials. With the

recent increase in the number of laboratories with facilities for this

type of testing, the widespread use of new types of materials (i.e.

thermoplastic and other synthetics), and recent application to carpets,

certain inconsistencies in test results have been reported. This

has raised serious questions by some safety experts and by certain segments of industry as to the use of the E 84 test for floor covering and

other interior finish materials.

Some of the questions which have been raised in regard to the

tunnel flame spread test merit technical consideration and are being

studied at the National Bureau of Standards (NBS) in cooperation with

the Department of Health, Education and Welfare (HEW). The following

aspects of the test are of primary concern:

1. the variability of results among different

laboratories,

*Figures in brackets indicate the literature reference at the end of the

paper

.

2
2. the merit of the test method for evaluating

flooring materials since the test requires

mounting a flooring specimen in a ceiling

position in the test furnace, and

3. the use of four different formulas to derive

the flame spread classification.

The question of variability of the test results is the principal

subject of this report, which deals with the reproducibility (among

laboratories) and repeatability (within laboratories) of the test

method based on round-robin tests of selected materials. The report

also gives survey results on physical features of each tunnel and some

of the deviations from the published standard method.

2. The ASTM E 84-70 Test Method

The purpose of the test is to determine the comparative surface

burning characteristics of material under test by evaluating

(1) flame spread; (2) fuel contributed; and (3) smoke developed.

The test establishes a basis on which surface burning characteristics

of different materials may be compared.

A specimen 20 inches wide x 25 feet long, usually in three sections,

is mounted and supported on the top ledge of a long test chamber. The

chamber consists of a masonry (fire brick) insulated horizontal tunnel

having an inside width of 17.5 inches, a height of 12 inches, and a

length of 25 feet. The tunnel is open at both ends, the "fire" and

"vent" ends. The specimen in a ceiling position, with the side to be

tested facing down, is subjected to diffusion flames from two gas

burners pointing upward at the fire end. Forced draft induced by a

3
blower and damper system at the "vent" end of the tunnel pulls air through

a small air inlet upstream from the burners into the fire end. A prescribed average velocity measured at the vent end prior to ignition is

required. After ignition, a constant negative pressure (draft) is

maintained and controlled by the damper system.. The flame and draft

serve to ignite the specimen and to induce flame spread along the ceiling

of the tunnel. Windows located on the side of the tunnel allow an

observer to record the extent of flame spread as a function of time. The

flame spread classification (FCS) is based on a scale which has 0 for

asbestos-cement board and 100 for select grade of red oak flooring. It

takes into consideration the distance or time of flame spread by using

one of four formulas.

The smoke developed is measured by a photometer system located some

distance downstream from the "vent" end. The 10 minute integration of

the time versus percent light obscuration curve from the photometer

reading forms the basis for reporting smoke developed, again relative

to the scale of asbestos-cement board as 0 and red oak as 100.

The fuel contribution is determined by the increase in the flue

gas temperature at the "vent" end. It is based on the 10 minute

integration of time versus temperature curve of the flue thermocouple

output during the test relative to the scale of asbestos-cement board

as 0 and red oak as 100.

The test conditions in the tunnel, air supply, and specimen

conditioning are controlled and/or recorded by various instruments.

However, certain details relating to materials of construction,

instrumentation and control are not included in the standard. No
mention Is made of the expected precision of the method or of the

number of tests required, for example. As a result, there Is considerable variation In tunnel design and procedures among laboratories

using the E 84 method. These problems have been referred to Committee

E 5.04 of ASTM for resolution In the past. At present there are six

task groups studying various aspects of the problem (see appendix C)

.

3. Interlaboratory Evaluation of Test Method

To obtain a realistic estimate of the variability of the test

method as It Is performed by the Individual laboratories, a collaborative

study sponsored jointly by HEW and NBS was Initiated. Eleven (11)

laboratories known to have a tunnel facility In this country and Canada

agreed to participate. Available data on previous round-robins, though

limited to only a few laboratories [2], and the effects of the test

method variables [3 , 4] were reviewed prior to this study.

A meeting, attended by representatives from nine of the participating laboratories, was held In October 1971 to discuss the detailed

procedures. At this meeting a suggestion was made to specify additional

calibration and measurement techniques not mentioned In the test method.

This was countered by others who held that the purpose of the round-robin

was to evaluate existing test practices In the various laboratories and

not to develop a new version of the test.

The procedure finally adopted was for all laboratories to follow the

E-84-70 test procedure to the extent practicable. Where deviations were

necessary, or where detailed procedures were lacking, each laboratory was

to follow Its own normal test procedures and provide notes on the

deviations and Individual Interpretations . The furnace leakage test of

5
paragraph 4.2 of the method was required and smoke bombs were made

available to each laboratory for pinpointing the leakage area if any.

Since the mounting of carpet specimens was a probable source of

laboratory variability and is not specified by the method, all mounting

on a backing board was performed by NBS before the materials were distributed. A prescribed randomized test sequence and detailed instructions

were supplied to the participating laboratories. A uniform data sheet

was also provided. A 2-minute sample presoak (specimen loading time)

before starting the test was required to help standardize the test procedure. A representative from NBS also visited each laboratory to make

air velocity measurements using a single calibrated anemometer, to survey

physical characteristics of the facilities, and to witness selected tests.

The procedures agreed upon were designed to give results based

essentially on the current practices of each laboratory and also to

provide a basis for comparing the effects of deviations for possible

future modification of the method. A supplemental questionnaire,

prepared by Underwriters' Laboratories, Inc. (UL) was sent to each

laboratory to help pinpoint the differences in construction and methodology among the facilities.

3.1 Participants

A total of 11 laboratories collaborated in this joint study. The

list of participants and laboratory abbreviations are given in Table 1.

The degree of experience in using the test method among laboratories

varies from less than a year to over 20 years. Some laboratories (UL,

UL/SAN, UL/CAN, NRC , SwRI, AMB, FM) test primarily for the public

6
Table 1. Participants of Interlaboratory Evaluation of the

ASTM E-84 Test Method

Abbre'"'la tlon

Mr. Tom Castino UL

Underwriters' Laboratories, Inc.

Northbrook, Illinois 60062

Mr. Alex Briber UL/SAN

Underwriters' Laboratories, Inc.

Santa Clara, California 95050

Mr. Norman Pearce UL/CAN

Underwriters ' Laboratories o£ Canada

Scarborough, Ontario, Canada

Mr. Calvin H. Yuill SwRI

Southwest Research Institute

San Antonio, Texas 78228

Mr. A. Rose NRC

National Research Council

Ottawa 7, Ontario, Canada

Mr. D. R. Crawford WEY

Weyerhauser Company

Longview, Washington, 98632

Mr. W. A. Ranzenberger OCF

Technical Center

Owens Corning Fiberglas

Granville, Ohio 43023

Mr. Robert Friedheim NG

National Gypsum Research Laboratories

Buffalo, New York 14217

Mr. P. G. Gott FM

Factory Mutual Research Corporation

Norwood, Massachusetts 02062

Mr. Lwwis G. Bricker AMB

Ambric Testing and Engineering Association

Philadelphia, Pennsylvania

Mr. Robert Robins HPMA

Hardwood Plywood Manufacturing Association

Arlington, Virginia

7
Table 2, test materials /Backing, and adhesiveSpecimen

Number Material

Nominal

Thickness

in

Red Oak Flooring 25/32

Glass Fiber Batts

Sheet vinyl

Lauan Plywood

Unfinished

Carpet A

Carpet B

Carpet A + Underlayment

Carpet C

Paperboard

(corrugated)

Asbestos- Cement

Board

Adhesive for

carpets

3/32

3/16

5/16

5/16

1/2

3/8

0.14

1/4

Dens ity

Ib/ft^ oz/yd^

2.8

0.11

0.64

0.45

0.17

2.5

0.13 Ib/ft^ applied

81

64

81

56

86

Description

NOFMA certified, Ozark

brand, clear plain top grade

Bismarck mill, 2 1/4" wide

tongue and groove.

Exposed surface, Neoprene

coated

.

"filled vinyl surfaces, inorganic felt backed.

Sanded, 4.4 mm, 3 ply panel.

Woven, level loop, Jut^

backing, pile 38 oz/yd , Acrylic, brown.

Tufted shag, 1 1/8" length

tuft, pile 24 oz/yd , jute

backing, Nylon

Same as #4

Rubberized hair felt pad.

Tufted, level loop, pile 20

oz/yd2, Nylon^ 1/8" foam rubber

attached pad.

125 # Test, B flute, Brown

(corrugated) paper.

Flexboard, Type F.

A. P. Green Insulation (silicate)

adhesive for mounting car- pet to ACB board.

All specimen sections were 20.5 x 96 inches^ except #1

8
whereas others limit their activities to research and development work

for their own company (WEY, OCF, HPMA, and NG)*. The laboratories are

identified in the report by code letters only, the usual practice in

round-robin studies.

3.2 Test Materials

In order to obtain meaningful results and yet not to burden the

participating laboratories with an excessive amount of testing, the

selection of materials was made by consultation with the participants.

Table 2 gives the relevant data on the materials and the adhesive

selected for the program. The materials selected represent common

construction and flooring materials, which included simple and composite

plastic, cellulosic and inorganic-base materials, varying in thickness

from 0.09 to 1 inch. The four carpet systems selected included two

types of synthetic fiber, woven and tufted level loop as well as tufted

shag construction, separate underlajmient as well as integral foam backing,

and an identical carpet both with and without underlayment . The materials

exhibited various forms of physical response to fire exposure such as

slow melting, fast shrinking, char formation, and delamination.

The expected flame spread classifications (FSC) for the materials

span a wide range, from about 25 to 1000. The test included materials

with relatively similar flammability in order to determine the sensitivity of the method. All materials were obtained from commercial

sources without special controls on uniformity except the pljrwood. All

specimens were cut, randomized, and mounted when necessary, before

* HPMA and NG would also accept testings from the public.

9
distribution. The carpets were cut parallel to the roll direction while

wood specimens were supplied with grain parallel to their length.

All materials were cut into three 8 foot sections except the glass

fiber batts which come in 25 foot rolls. Carpets were cemented to a

standard 1/4 inch thick asbestos cement board (ACB) using an adhesive

(silicate) applied to the rough side of the board. For the carpet tested

with underlayment the latter was first cemented to the ACB board and

the carpet then stapled on top of the underlayment using 1 1/8" length

staples spaced 10 inches apart in both directions (staple penetrates the

underlayment only) . Wire mesh screen (1-inch hexagonal chicken netting)

laced with tie-wire in the back of ACB board covered the front of the

specimen. The procedure of using either staples or wire mesh screen to

prevent fallout is typical of practicing laboratories. The combination

of staples and screening for these tests was intended to minimize

separation between the carpet and underlayment, and thus to reduce a

source of variability in test results.

Normally, sheet vinyl floor covering is adhered to the ACB board

with an adhesive that would keep the flooring from delaminating from

the substrate during the test, but for this work the material was treated

as a thin laminate and procedure A1.8 in the test standard was followed.

The procedure used consisted of placing 1/4" diameter steel rods, spanning

the width of the tunnel at 2-ft intervals to support the specimen. A

similar method was used on the glass fiber batt except that the rods

were inserted through the center of the material.

10
The densities of the pljrwood panel specimens are given in weight

per A X 8 ft sheet. The density distribution is considered better than

normal for commercial material of this type since about 20% of the panels

from the high and low density ends of the lot were removed before distribution. The mean and calculated standard deviation for the material

used are 14.5 + 1.3 lb/panel for all the panels and 15.0 + 1.4 lb/panel

for those used at the first section of the furnace. With some exceptions,

the panel with the highest density among a set of three randomized

specimens was placed at the fire end of the furnace.

Red oak flooring was purchased in a single lot from a mill in

Bismarck, Missouri, randomized and distributed as reference material.

Though specimen selection and mounting were performed by NBS,

specimen conditioning in accordance with the E-84 specification of

70 + 5°F and 35 - 40% RH was performed by each laboratory. The moisture

contents of the red oak specimens after conditioning were also reported.

3.3 Experimental Design

Each laboratory began the test program with 3 specimens of red oak,

a reference material supplied by NBS. If the calibration test results

were within the expected range in flame spread based on past experience

(100 + 5), the laboratory was to proceed to test other materials

following the test sequence table assigned by NBS. The table was based

on randomization of 21 tests (3 replicates and 7 materials) for each of

the 11 laboratories. Individual laboratories were allowed to choose,

prior to the testing program, an option of 2 or 3 replicate runs per

material. Most performed 3 replicate runs, giving a total of 210 out

of a possible 231 tests, excluding red oak.

11
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12
A total of 8 materials including A carpet systems were used in the

test program. Two carpet systems and 4 other materials were tested by

all 11 laboratories, one carpet system by 5 laboratories and the othel

carpet by the remaining 6 laboratories. A comprehensive data sheet,

based on suggestions from participants, was required for each test. A

sample is shown in Appendix A.

4. Survey Results

4.1 Physical Characteristics of Furnaces

Selected tunnel characteristics of each laboratory are listed in

Table 3. These were obtained by direct measurement during the authors'

visits to the laboratories and by data furnished by the tunnel operator.

It is not the purpose of this study to show correlation, if any,

between any of the characteristics and test reproducibility. But these

data should form a useful basis for comparing each tunnel with the

present E 84 requirements and for possible use in future revision of the

test method standard.

4.1.1 Furnace Windows

According to Table 3, only 3 laboratories conformed to the specified

description of windows, namely of the single, recessed type. (See

Appendix B for a sketch of the furnace required by the Standard) . Others

used double or single flush (inside) windows. The purpose of adopting

double windows was to reduce air leakage and possibly smoke deposits on

windows to improve observation. To compensate for the loss of flow

turbulence in the tunnel where the recessed part of the window is

covered in the double type window, a common practice is to introduce

5 or 6 bricks (position not standardized) at intervals on the wall
and floor edges along the tunnel. Experiments have shown that these

bricks are necessary to meet the burning time requirement for the red

oak standard reference material. Figure 5 shows the double-type window

with brick (top) and the recessed-type window (bottom)

.

4.1.2 Location of Manometer and Photometer

The locations of the draft manometer to control flow and the photometer to measure smoke are not specified in the method. The drawing

(Figure 1 in the Standard), shows that the photometer is further downstream from the "vent" end than the draft manometer. These distances

from the "vent" end in the 11 tunnels listed in Table 3 varied from

about 3 to about 34 feet for the manometers and from 3.5 to 40 feet for

the photometers.

All photometers were oriented the same way, on a vertical axis,

with the detector located at the bottom as indicated by the drawing in

the standard

.

4.1.3 Draft Control

The regulation of draft pressure in the tunnel may either be

manual or automatic according to the method. A few laboratories used

the automatic method. The response time of the regulator is not

specified in the method. Automatic regulation is generally more

consistent if not faster than manual regulation.

Data indicate that, depending on the type of material tested,

variation in draft pressure within a single run is typically + .01 inch

for a negative pressure of 0.075 inch of water.

14
A. 1.4 Furnace Air Velocity and Temperature

The method requires a linear air velocity of 240 + 5 ft/min average,

measured at seven positions near the "vent" end. Most laboratories used

a thermal anemometer or a deflecting vane type velometer for such

measurements. Because of the continuous fluctuation of the pointer in

these instruments caused by turbulent flow, the uncertainty in each

reading is believed to be at least + 15 ft/min.

To measure air velocity variations among laboratories in this

survey, a single 4 inch rotating vane-actuated anemometer (Bendix-Friez)

was used. It was placed at the center, midheight and about one foot

before the "vent" end of the tunnel. To observe dial readings through

a tunnel window from the outside, a light source aimed at a small mirror

mounted below the dial was also used.

The rotating vane type anemometer measures the total flow passing

through its rotor while displaying the cumulative results on its dial,

similar to gas meter. The calculated velocity is in itself an average

over the time period of measurement and the cross sectional area within the

4 inch diameter. This type of anemometer, if calibrated, is believed to

be more suitable in terms of precision and accuracy for the purpose.

The velocity data in Table 3 are only a comparison, at the time of

measurement, of air flow values determined by the reference anemometer

and anemometer of each laboratory. For the fire tests, the required

240 + 5 ft/min average velocity based on the regular measurement method

of each laboratory was used.

15
Furnace air temperature during velocity measurements by the

reference and laboratory anemometers is also given in Table 3. The

test method is not explicit on the temperature at which velocity calibration is to be made. Experimental data by Robins [6] showed that

velocity decreased about 12 ft/min (from 252 to 240) when air temperature

increased 20°F (from 72°F to 92°F) under a constant static pressure of

-0.075" water. The effect of temperature on velocity measurements at this

range, though small, can be a source of error if not specified in the

method. However, as pointed out by Armstrong [7] the practical effect

would be insignificant in view of the extreme variation in temperature

and hence velocity that exists after ignition and during the tests from

one run to the next.

4.1.5 Thermocouple Type and Mounting

Aside from the diameter of the thermocouple wire the method does

not specify type of junction, exposure length, mounting technique and

size of the thermocouple post for flue gas measurement. A comparison of

those parameters is also included in Table 3.

4.1.6 Relative Humidity of Intake Air

Temperature and relative humidity for the intake air to the tunnel

furnace as well as for specimen conditioning are very specific in the

standard. Many laboratories used a very elaborate system to maintain

these conditions. However, some laboratories do not strictly adhere to

the 35 - 40% relative humidity requirement at all times because of

heavy testing schedules and/or adverse weather conditions. Data in

Table 3 gives RH values based on typical reported values in the data

sheets. Some laboratories only condition the specimens.

16
17

19

Figure 5 , Examples of windows and bricks

21
Figure 6, Examples of burners

22
4.2 Illustration of Furnace Characteristics

Figures 1 and 2 are photographs showing overall views of the tunnels

in eight (8) of the laboratories that participated in this study. Note

the contrast between tunnels shown in the photographs. The variations

of photometer locations (distance from "vent" end) and the elevation of

the exhaust duct relative to the tunnel are illustrated in Figure 3.

Figures 4 and 6 illustrate the variation in thermocouple and burners

construction respectively among tunnels. The difference between singlerecessed windows and double type windows as well as the location of

bricks for turbulence are shown in Figure 5.

5. Results of Tests

Data for flame spread classification, smoke developed, and fuel

contribution from each laboratory are tabulated in Tables 4, 5, and 6

respectively. These were based on results calculated by the operator

at each laboratory relative to his own red oak reference of 100.

Figure 7 shows a plot based on the mean of all laboratories versus the

means of each laboratory for flame spread of all materials.

Table 7 shows the moisture content, burning time, FSC, smoke, and

fuel contribution of red oak reference material supplied by NBS. Except

for one laboratory the FSC results are in general agreement with those

obtained by each laboratory in their own calibration. The excepted

laboratory (D) based its own calibration on red oak grown in a different

region of the country relative to that used by others. The method of

moisture measurement and moisture content limit for Red Oak reference

are not specified in the standard.

23
- 1000

- 800

600

5

55 400 o

uCO

- 200 g

50 100 150 200 250

MEAN FLAME SPREAD (FSC) OF ALL LABORATORIES

275 640

Figure 7, f%AN fsc of each lab. versus mean fsc of all laboratories.

24
Table 4. TEST DATA ON FLAKE SPREAu (FSC).

MATERIALS

Labs 1 2 3 4 5 6 7 8 0

A 23 44 262 36 176 254 1100 99

26 49 231 28 135 264 1320 93

23 44 220 33 145 236 1100 95

B 15 38 69 49 157 275 74 100

15 38 170 46 157 275 76 98

18 41 116 98

C 26 72 189 33 152 208 580 95 26 69 185 77 147 208 500 98

28 69 ^ 185 33 163 226 98

D 23 51 122 36 145 208 1100 86 23 46 71 36 143 222 920 89

23 43 75 36 (367) 220 920 94

E 30 80 100 30 155 220 510 97

25 70 75 35 140 215 610 98

25 65 80 98

F 18 38 165 33 169 232 72 108

21 38 74 54 179 236 825 104

21 41 200 33 173 220 550 98

G 18 46 220 51 110 244 440 105

18 46 183 46 100 200 550 98

13 51 200 48 110 244 733 100

I (13) 25 271 61 207 331 1000 104

21 31 211 41 183 301 1000 100

25 25 214 46 200 301 1000 98

J 26 39 77 41 197 289 688 106

2b 37 154 41 192 308 56 102

27 40 196 44 199 284 69 97

77 / J

O O Q lUU

23 59 73 33 73 228 100

23 57 75

L 21 51 200 71 (367 ) 275 1000 90

21 51 190 41 (412) 285 96 21 51

~ Units based on red oaV - 100.

25
Table 5, jeST DATA ON SMOKF LEVELOPED ^'

MATERIALS

Labs 1 2 3 4 5 6 7 8

A 15 225 95 75 135 145 25

20 240 70 75 135 175 15

15 195 85 130 135 225 80

B 44 241 23 102 125 510 18

19 231 64 201 114 447 18

28 260 87

G 15 205 71 18 103 177 10

17 235 70 (148) 147 180 8

14 254 65 44 113 204

D 36 252 53 55 86 140 17

18 208 64 65 80 206 26

18 205 76 77 (88) 156 23

50 o o c loo 576 50

35 315 85 70 360 565 55

25 300 80

F 98 540 70 162 280 5 56 585 100 195 370 550 25

55 590 67 69 290 1000 31

58 154 46 117 88 188 46

6 58 162 78 170 65 218 60

60 165 72 150. 72 170 67

I 242 63 279 132 447 32

11 179 253 168 395 11

16 132 237 132 374 11

J 24 Ilk 91 169 111 365 18

36 229 71 211 97 374 7 23 215 66 224 ICQ 382 16

K 12 189 48 75 72 155

17 225 60 74 69 155

14 210 92

L 12 305 140 210 150 560 110

14 285 135 25 130 525

23 275

— Units based on red oak = 100.

2G
Table 6, jf.c;t DATA 0^^ FIIFL CnNTRIHIITinN-'

MATERIALS

Labs 1234 5678

15

10

10

85

85

20

20

30

35

40

40

60

70

70

15

35

25

12

20

13

Ik

41

56

10

32

34

31

98

84

6

13

11

10

9

11

69

82

51

72

28

14

19

48

57

64

61

63

66

29

29

0

18

18

60

40

55

19

20

20

. 45

70

(26)

50

72

52

29

13

28

5 10

LO

55

40

40

15

15

55

55

80

80

15

40

13

12

312

33

37

38

214

9 11

46

34

48

30

55

80

133

171

154

3

3

5 45

25

45

48

62

57

43

46

38

45

81

73

81

97

94

96

97

92

187

148

156

54

58

4

11

16

63

46

56

56

319

44

34

53

8

9 10

25

20

31

76

80

71

15

26

K

11

13

12

5

2

21

19

22

50

40

52

121

125

6 14

16

10

16

6

62

77

107

98

27

71

41

a/— Units based on red oak =100.

27
Table 7. Results of Specimen Moisture, Flame Spread, Fuel Contribution,

and omoKe on Keu uaK. ouppi.iea Kit 'M'R C Dy JNiJo

Moisture^^ "F 1 sinA op ITccLU. r ucX

Method/ percent Time, min FSC

A

t\ J . o QQ O J

Oft y 0

- - D . 0y J xuu onyu

6.1 95 70 90

uo ww H.J J . _) iUU xiz iUx

A.

3

c 7 J . / QQ y J XU J 4.5 5.7 98 90 89

n\j p 6 5 y J 1 1 00y y

6.5 yo Oh 09yz

6.6 5.7 98 38 91 nu w 5.9 7 7 oo XZ.U 1 9n oo 5.8 7 1 oy XU7 o / 6.0 6.3 94 95 101

p

Ci p 6 5 07y / oy 00y y 6.5 t; 7 yo xxu OA

5.8 98 102 102

r p 5 8 J . X xuo JH«^A xuu 6.3 J.J 09yz OA7H

6.4 5.7 98 92 91

n p U.J5 J

.

XU J 00 xuu

6.7 J . o y o xuz 1 09 QQ

6.7 5.5 100 102 100

T

X w 6 J.J xuu 1 no

7 J.J^ xut X JJ XH1 AnU

AvJ 5.7 98

T w 6.7 J . z XUD OA xuu 1 no 7.5 5.4 102 99 100

6.4 5.9 97 107 90

VIS. p 6.7 c c J . J

1xuunn XX J 07y / 6.6 5.5 100 108 98

L p 7.3 6.8 90 56 80

6.8 6.0 96 85 95

P = Conductivity moisture probe. W = Weigh loss after heating. W Based on E 84, time to end of tunnel.

cj Based on calibration standard of each laboratory using red oak = 100.

28
5.1 Statistical Results

One of the purposes of the interlaboratory evaluation of the test

method was to determine the degree of uncertainty of the resultant data.

Table 8 summarizes the results on flame spread, smoke, and fuel contribution in terms of the means, ranges, and the within-laboratory

(repeatability) and between laboratory (reproducibility) coefficients

of variations for each material. The repeatability and reproducibility

data are given in terms of the expected precision of a single determination within a single laboratory and a single determination among the

laboratories respectively. The values were derived from a "betweenwithin" analysis of variance made separately for each material [5,8]. A

weighting factor was used to normalize results between two and three

replicate runs. The analysis is based on all the data from the 11

laboratories except the 4 values in parentheses in Table A which resulted

from errors in test procedure (the incorrect surface of Material #1 was

exposed in one case and asbestoes papers were used on the furnace floor

in the other cases). Because of the wide scatter in numerical values on

FSC for material #8, data less than 77 were excluded from the calculation

for coefficient of variation.

It is meaningless to express an overall reproducibility and repeatability for all materials tested because the results appear to be material

dependent. For most materials, reproducibility would improve only slightly

if it were based on the averages of 2 or 3 replicate runs. For a method of

converting the statistical result to that based on more than single tests,

see Appendix E.

29
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30
5.2 The Use of Other Formulas for FSC Calculation

Because of anomalies in some test results caused by the application

of four sets of formulas in the calculation of FSC, many methods have

been proposed to avoid the problem. The method in the present standard

calls for the use of four completely different methods of calculation

depending on the time and on whether or not the flame spread reaches the

far end. As a result some normal measurement errors are exaggerated by

the discontinuity in going from one formula to another. See Appendix D.

One of the earlier proposed methods, for example, is based on "rate",

FSC = 28.2^, where d is maximum distance burned (ft.) and t is the

corresponding time (min.) to reach the maximum distance regardless of

whether or not the flame reaches the end of the tunnel.

A more recent (Dec. 1972) proposed method made by the task group on

the E-84 calculation method under ASTM Committee E5.04 is based on the

following "area" formulas:

FSC = 0.564 A for A<_ 97.5 ft min.

FSC = 5362/(195-A) for A> 97.5 ft min.

where A is the integrated area under the curve based on the flame or

burned front distance as a function of time on the last 19 1/2 ft of the

specimen during the 10 minute test period. Of several alternate calculation methods, this method has the advantage of minimizing differences

in results obtained from the present standard and the proposed method.

If this method is adopted, it is essential to define flame or burned

front in the standard more explicitly, since its correct interpretation

is much more critical in determining the result than that in the present

standard. The flame front or flame spread is not defined in the present

31
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32
standard. Various operators have different techniques for judging the

front. Their judgements are often complicated by the difficulties in

viewing through heavy smoke deposits on windows from certain specimens.

These sources of interpretation and reading errors require study.

The anomaly from using the standard calculation is particularly

noticeable in the results on material #3, pljrwood. Flame spread data

for this specimen are used as an example to compare the results of

applying each method of calculation. Table 9 presents data on material

#3, giving specimen density, furnace position of each specimen, time and

distance of maximum travel, and results of FSC by the standard and two

proposed methods of calculations. Input fuel rate and starting temperature were included to show the normal test variations, also typical in

tests of other materials.

6. Discussion

6.1 Tunnel Construction Variables

The differences of detail in construction and measurement techniques

among laboratories, as shown by Table 3, are obvious. The relative

effect of any of the variables (i.e. smoke meter location, windows,

velocity control etc.) on the results is difficult to assess by looking

at these data alone. However, gross effects not easily masked by other

variables can sometimes be detected. For example, the consistently high

or low smoke results from Laboratories D, E, F and G on several materials

may have been caused by differences in their sm.oke measuring system

relative .to that of the other laboratories as shown in table 3. Leakage

may also contribute to the low values for laboratory G since it did not

follow the leak-test procedures.

33
The smoke value in the standard is determined by the ratio of the

area under the smoke obscuration curve for the specimen and for the red

oak reference. Since both specimen and reference are subjected to the

same exhaust duct and photometer measurement system, the effect of any

existing bias should in principle, be compensated. This is not valid for

two reasons. One is due to the fact that smoke concentration (mass or

optical) is not proportional to obscuration but to the log of reciprocal

transmission. Because of the compression at the higher end of the log

scale, the concentration ratio of two smokes will vary depending on the

actual magnitude of the smoke value for the reference material. Since the

level of obscuration from the reference material is determined by the concentration of smoke reaching the photometer and by its path length, unequal

losses in ducts resulting from differences in design become important.

A second factor which may explain the inadequacy of using red oak

for a smoke reference is the mechanism of smoke loss. For example, the

coagulation and decay of wood smoke which consists mainly of condensed

liquids is extremely temperature dependent whereas the decay of synthetic

carpet smoke (mostly carbon particulates) is much less temperature

sensitive but coagulation-time dependent. Therefore, a tunnel with a

cold and short duct, say, will result in a low reference value for red

oak and thus give a higher ratio for carpet smoke. On the other hand,

a hot and long duct will tend to increase the time for coagulation losses

but not condensation losses. This will result in a lower value for

carpet smoke

.

Specimen #3, pl3rwood, has the lowest variability (between-laboratories)

in smoke among the materials tested. Based on the reasons mentioned

34
above this is not unexpected. The normalizing factor of using a

reference material is more effective when the specimen and reference

smokes are similar in nature. This also indicates the need to study

the problem of selecting reference materials.

There is general agreement among the laboratory operators on

attributing part of the large variability of smoke results to the lack

of a specification on the smoke photometer and its location. However,

we believe that to attain reasonable reproducibility in test results,

the smoke measurement system including exhaust duct length, insulation,

photometer path length, instrument range, etc. should be standardized

in all tunnels

.

The causes of variability in fuel contribution is not clear. For

example, laboratories that rank first or second in terms of high value

in fuel contribution for all materials are Laboratories G, I and L.

These are 3 of the 4 tunnels using the single-type windows and without

turbulence bricks. The bricks are not required by the present standard.

Certainly the lack of uniformity in thermocouple type, location, and

mounting method among tunnels is a factor contributing to the variability.

Perhaps in future modifications several thermocouples should be used in

each tunnel to minimize the effect of high temperature gradients which

make the location of a single thermocouple very critical. A means to

minimize soot deposit on the junction of the thermocouple is also needed.

This should improve the reproducibility of the test method.

In addition to the factors mentioned, some operators attribute the

variability of smoke and fuel developed to the physical condition of

35
Table 10 . Mean FSC for Each Materi al and Laboratory

Lab

Materials

1 2 3 4 5 6 7 «

A 24 46 238 32 152 251 1170

DD 16 39 118 47 157 275 75

rt 26 70 186 33 154 214 540

\\V 23 47 89 36 144 217 980

rt 27 72 85 32 147 218 560

c

r 20 39 146 40 173 229 482

pu 16 48 201 48 107 228 574

Ti 23 27 232 49 197 311 950

1vj 26 39 142 42 196 293 271

1/ 23 57 75 28 73 228

L 21 51 195 56 390 281 1000

Taole n FSC Ranking of Materials uy Eacn Laboratory —

Lab

Material

s

2 3 4 5 6 7 8

ft 3 5 2 4 6 7

aD 2 5 3 6 7 4

r

3 5 . 2 . 4 6 7

n 3 4 2 5 . 6 7

t 3 4 2 5 6 7

c

r 2 4 3 5 6 7

la 2 5 3 4 6 7

T *

.1 2 5

'3' 4 6 7

1u 2 4 3 5 6 7

K 3 5 2 4 6

L 2 4 3 6 5 7

a./ Based on mean of 3 or 2 runs.
ledges and covers of the tunnel as well as to the size of the flame as

a result of burner variation.

6.2 Results of Flame Spread Measurement (FSC)

Tables 10 and 11 give the average value of FSC for each material

and the rank ordering of the materials by each laboratory respectively.

It is unrealistic to expect good agreement in ranking between materials

#2 and #4 and between materials #3 and //5 because of the close proximity

of FSC values. Otherwise most laboratories agreed on the relative ranking

of the materials tested.

In terms of code classification based on NFPA Code 101, (1970)

there is good agreement among laboratories on five of the materials

(Materials 2, 4, 5, 6 and 7) in Table 12. But the discrepancy on the

other three m.aterials, though explainable, may be of the type that has

caused concern in the past to material producers who must meet code

requirements which use specific ranges of values for material classification.

The variability of the FSC for the carpets tested does not appear

excessive relative to other types of materials. The poorest in terms of

reproducibility is material #5, a shag nylon, where the average for the

lowest laboratory (except laboratory K) was 107 and for the highest

laboratory was 197. There were two individual runs in which the values

were slightly over 200, which would have disqualified it as a Class C

material. Data on material #5 from laboratory L is excluded because of

the use of asbestos paper on the furnace floor. The value of Lab. K

would become 111 and closer to the mean, if the new method of

calculation based on "rate" were adopted.
TABLE 12, Code Classification of Materials"

1 ab

Materials

1 2 3 4 5 6 7 8

A A B D B C E

B A B C B C D B

C B B C B C D E

D A B C B C D E

E B B C B C D E

F A B C B C D D

G A B D B C D E

I A B D B C D E

J B B C B C D D

K A B B B B D

L A B C

B D D E

±1 Based on average flame spread (FSC) of 3 runs NFPA Code 101, Life Safety Code Classification (1970)

A = 0-25 FSC D = 201-500 FSC

B = 26-75 FSC E = over 500

C = 76-200 FSC

38
The carpet results also indicate the effect of including the

underlajnnent in the test. Identical carpet specimens (//4 and #6)

gave an average flame spread classification of only 42 without and 278

with underlayment . This points out the need for knowing whether underlayment was used in the reported test results, and whether it will be

used in the proposed application.

The variability of FSC for material #1 (fiber glass batt) is

numerically small. A level of 25 is used as a cut off point between

Class A and B by most code authorities. Six laboratories rate the

material in Class A. Two rated it in Class B, and three rated it in

A or B depending on the particular run.

6.3 Effect of Using a Single Formula for FSC Calculation

The between-laboratory variability of FSC results for material #3,

plywood panel, was of the order of 43%. The variability is exaggerated

by using the two formulas required in the method for calculating the

FSC, depending on whether or not the flames traveled the full length of

the specimen. Undoubtedly some of the variability was a result of

2 variation in specimen density, (Range 0.40 to 0.53 lb/ft ) a normal

range for a commercial product of this type. For example, the 1st and

2nd runs of Laboratory J in Table 9 were similar in rate, but because

the flame front stopped within a half foot of the end for the first run,

the FSC value was 77, compared with 154 for the second run where the

flame reached the end of the specimen. In spite of the difference,

however., both would be Class C (76-200) under the NFPA Code 101 Life

Safety Code Classification. Table 9 also shows that in some cases (i.e.

Laboratories D, F, J) the same material could be classified as Class B

39
12 13 14 15

DENSITY, lb/sheet (4x8 ft)

Figure 8, Fsc as function of density of specimen B based on the present (bottom)

AND "rate" (top) formulas, A DaTA AFFECTED BY CHANGE OF FORMULA,

40
(26-75) or Class C (76-200) even within a single laboratory under normal

testing variability caused by the use of 2 sets of formulas. For this

reason material producers have in the past frequently questioned the

precision of the test.

If the "rate" or "area" method was used in the calculation, as

shown in Table 9, the exaggerated scatter in results would be minimized.

This is further illustrated in Figure 8 where the FSC results for the

plywood panels are plotted as a function of density of specimen at the

burner section of the tunnel using the present and the single "rate"

methods for FSC calculation. Observations by others [6] show that the

panel section at the fire end has proportionately more effect on the

result.

Figure 8 shows the limited dependence of flame spread on density

of the panel. Specimens less than about 13 lb/panel did not produce

sufficient fuel for a complete burn to the end (FSC<100). The data

spread of FSC for the 14-15 lb/panel group is wider than that of the

15-17 lb/panel group based on the present two-formula method. An artificial barrier near FSC of 70. is evident in Figure 8 (bottom). Results

based on a single formula as shown in Figure 8 (top) appear to be more

credible. Either of the two proposed methods of calculations will

improve on the consistency of test results compared to the present

formulas

.

The complexity of the problem in using the tunnel data for the

evaluation of flame spread hazard is further shown in Figure 9. It

shows the flame spread distance as a function of time for each of the

materials tested based on typical runs. FSC values based on the Standard

41
UJ

Ico

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(D

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42
and one proposed method (area under the curve) of calculations are

also given. Materials have different induction periods, and varying

flame front velocities as well as different times of arrivals at the end

of the tunnel. The factors used to formulate a rating method such as FSC

may necessarily be arbitrary - but good repeatability of test results

should be an important criterion.

7. Conclusions

Based on the test results from eleven (11) laboratories using the

ASTM E 84 (tunnel) method involving 240 tests on 9 (8+ reference)

materials, observations and measurements of tunnel facilities, and

discussion with operators, the following conclusions are presented.

1. For a randomized sample of red oak, the standard

reference material, 10 out of 11 laboratories obtained

results in fair agreement with their previous calibration

defined as 100 for flame spread classification (FSC) and

fuel contribution. Individual values, from the 10

laboratories ranged from 90 to 108 for FSC and from 80 to

140 for fuel contribution. For smoke developed the

agreement is not as good; it ranged from 38 to 135.

2. The median test reproducibilities in terms of the

between-laboratory coefficient of variation for

the eight (8) materials tested are as follows:

Flame spread classification, 27% (ranged from 7 to 43%)

Smoke developed 57% (ranged from 34 to 85%)

Fuel contribution 64% (ranged from 22 to 117%)

43
The test reproducibility of the A carpet systems

tested in terms of coefficient of variation for

flame spread (FSC) ranged from 7 to 29% calculated

on the basis of single tests in different

laboratories. . - . ;,

Use of different calculation methods for FSC improved

the reproducibility of results for the plywood. Similar

improvement is expected on other borderline materials.

There are significant variations in construction

and in measurement techniques among tunnels because of the lack of detailed specification in

the test method standard. It is reasonable to

assume that these variations affect the

reproducibility of the test results.

The rating of material using the NFPA code 101

(1970) classification method (i.e. A, B, C, D

and E) shows good agreement among laboratories

on five of the materials and poor agreement on

the other three materials.

8. Recommendations

More detailed specifications, improved design,

and standardization in the construction and

operation of tunnel furnaces are needed in order

to improve reproducibility in the measurement

of flame spread, smoke and fuel contribution.

This would serve all concerned including code

44
officials, consumers, producers and the testing

laboratories.

Tunnel operators should meet, discuss and implement

solutions to the interlaboratory variability

problem. Task groups in ASTM E 5.0A have been

formed to examine various facets of the problems.

Since recommendations for improvement are urgently

needed, concurrent study by others should be

encouraged and supported.

Organizations who use the test results from the

ASTM E 8A test metho4 for regulatory purposes

should be consulted. Their views and legal

authority are needed in order to support, supplement,

expedite and enforce recommendations from the task

groups studying the problem.

The reproducibility of measurement of smoke and fuel

contribution reported in this round robin is not

acceptable. Alternative methods for smoke and

potential heat measurement are available.

45
9 . Acknowledgement

The participating laboratories performed all tests without

compensation. The valuable contributions in terms of advice and

generous cooperation from the staff, of each laboratory are gratefully

acknowledged. The Carpet and Rug Institute donated all the carpet

specimens. Owens-Corning Fiberglas, Hardwood Plywood Manufacturers

Association, and Armstrong Cork Company provided the necessary fiber

glass batt, plywood panel, and sheet vinyl flooring specimens,

respectively. Consultation on statistical problems was provided by

Dr. J. Mandel, Statistical Consultant, Institute of Material Research,

National Bureau of Standards. .. .

In addition to NBS, the following organizations provided financial

support to the project: , >,.. ,

. ? s,,-,

Health Services anfi Mental Health Administration-HEW

Public Building Service-General Services Administration

Naval Facilities and Engineering Command

Veterans Administration ,

The draft of this report was made available to the participating

laboratories for comment and data verification. Most comments were

useful and were accepted. Others, especially those on the influence

of tunnel variables on results, though valuable, are not considered within the scope of this paper, but would be available to the task groups.

46
47
Appendix B. Dimension of ASTM E-84 Furnace

Tf.st loji Surface Bubmng Characteristics of Building Materials (E 84) 413

To Orah Light Sheet Vetol Removable Chomber Source Vent Pipe Top Ponel / c^^^ 25 ft - Length of Test Sample

Adiustable Shut'er^

Vents \ Photo- \ for Gos \ electric \

Analysis Cell

Manuolly Opprated Domoer

Seetion"c-C"

Vent End ^^Thermocouples'

6" by 6" Window- Door

^Differentiol Manometer Tube

U.S. Cnstomary Units 2H by 11% in. 6 bv 6 in. 12 "± M in. 17M ± M ia. 25 ft.

19 Windows ?i by ll|

i + i 2-2

Gas-

\ Supply Fire End

for Igniting- . Fire /

Opc.iny for

Air Supply

J I2"i5

i —

r

Section A-A"

Metric liquivalents 7.0 by 29.8 cm

15 bj 15 cm

30.5 1.3 cm

44.4 d:: 1.3 cm

7 . K. 2 m

Fig. 1 —TestjFurnace Showing Critical Dimensions.

Sand or Liquid Seal /Removable Top Panel ^" Asbestoi -Cement Board

Vision (f Ponel

Cosloble Refractory (max temp 2500 F)'' Section "B-B"

I.S. Customary Units Metric Equivalentj Kin.

2 in. 4 in. 20 in.

6.3 mm

6.1 cm

10 .2 cm

50.8 cm

U S. Customary Units Metric Equivalents

9 by 4I/2' by 2K in- 23 by 11 .5 by C.5 cm

1800 F

2500 F

2600 F

982 C

1371 C

1427 C

Fig. 2—Test Furnace Showing Critical Dimensions (Section "B-B").

40-3 48
Appendix C. Task Groups Under ASTM E 5.04 to Study Revision of E 84 Test

Method Standard (organized between 1967 and Oct. 1972):

1. Specimen Mounting Methods for E 84.

2. Flame Spread Calculation Methods for E 84.

3. Revision of the Scope in E 84. (To or Not to include carpets).

4. Evaluation of Procedures on Smoke Measurement in E 84.

5. E 84 Tunnel Operator's Group.

6. Criteria for Evaluation of Laboratories Conducting E 84 Tests.

49
Appendix D. Method of Flame Spread Classification (FSC)

Under the Current E 84-70 Standard

6. Classification

6.1 The flame spread classification (FSC) shall be determined

as follows:

6.1.1 For materials on which the flame spreads 19-1/2 ft

(5.94 m):

6.1.1.1 In 5-1/2 min or less, the classification shall be 100

times 5-1/2 min divided by the time in min (t) in which the flame

spreads 19-1/2 ft (5.94 m) , (FCS = 550/t) .

6.1.1.2 In more than 5-1/2 min but not more than 10 min, the

classification shall be 100 times 5-1/2 min divided by the time in

min (t) that the flame spreads 19-1/2 ft (5.94 m) , plus 1/2 the

difference of 100 minus this result, (FSC = 50 + 275/t) .

6.1.2 For materials on which the flame spreads less than

19-1/2 ft (5.94 m) , and then ceases to continue or recedes in a

10 min test period.

6.1.2.1 When the extreme flame spread distance (d) is more

than 13-1/2 ft (4.11 m) and less than 19-1/2 ft (5.94 m) , the

classification shall be 100 times 5-1/2 min times the distance (d)

divided by 19-1/2 ft (5.94 m) times 10 min, plus 1/2 the difference

of 100 minus this result, (FSC = 50 + 1.41d) FSC(metric) = 50 + 4.62d).

6.1.2.2 When the extreme flame spread distance (d) is 13-1/2 ft

(4.11 m) or less, the classification shall be 100 times the distance

(d) divided by 19-1/2 ft (5.94m), (FSC = 5.128d) (FSC (metric) = 16.84d).

50
Appendix E« Calculation of Reproducibility Based on the Averages of

Replicate Tests

Ll 2 ^ Ws'

Bm =t/B - Ws + — V s m

Wm =

"tit* where Bm

Bs

Wm

Ws

m

Between-labs, coefficient of variation, (c.v.)> between averages

of m replicates in different labs.

Between-lab. C.V., between single tests in different labs.

Wi thin-lab. C .V. , based on the averages of m tests in a

single lab.

Wi thin-lab C.V. based on single tests in single lab.

Number of replicate runs.

51
References

ASTM E-84-70, Standard Method of Test for Surface Burning Characteristics of Building Material, 1971 Annual Book of ASTM Standards,

Part 14, American Society for Testing and Materials, Philadelphia,

Pa. 1971.

C. H. Yuill, "Round Robin Tests on Tunnel Type Flame Spread

Furnaces for ASTM," Southwest Research Institute, San Antonio,

Texas, April 1959.

There are other correlation works between UL and one or two other

laboratories.

Endicott, L. E., and Bowhay, R. B., "A Statistical Evaluation of

the Fire Hazard Classification Furnace (ASTM E 84-68)" Material

Research and Standards 19, 10, 1970.

Castino, T., Report on October 17, 1968 Meeting of Representative

of Operating Tunnel Test Facilities, private communication.

Brownlee, K. A., "Statistical Theory and Methodology in Science

and Technology," John Wiley and Sons, Inc. (1965).

Robert Robins, Hardwood Plywood Manufacturing Association, private

communication, data, 5/30/72.

George Armstrong, Southwest Research Institute, private communication,

letter, 11/13/72.

J. Mandel and R. C. Pauli, Anal. Chem., 42^, 1195, (1970).

52
r or<N'. KnS-il''iA c.-. i)

li.S. DcIl - I . Or COMM.

PI3LiOGr;APHIC DA KBoIR 73--I25

Gov'' Accession

4. T ITLE AM) SU ) rj i i l.!.-; Iv,t:erlabo::acory Evaluatr.on of the Tunnel Test (ASTM E8A

)

Applied to Floor Coverings

7. A^JTIIOR(S)

T. G. Lee and Clayton Huggett

9. PERF01U;iNG ORGANIZATION NAMil AND ADDRESS

NATIONAL IHiREAU Oh STANDARDS

''DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

3. KecipiL-fu' s Acci-ssic/ii .'".'o.

5. i-'ublic aucni Dr.f

April 1973

6. Periormiug Orf.auii:atic.'i Cc.,-ic8. l^erformirig Organ izr. tic^ NBSIR 73-125

10. Pro|cct/Task/Work U nit Xo. i 4906401 I

11. Contract/Grant No.

12. Sponsoring Oiganization Name and Address

Department of Health, Education & Welfare

Washington, D.C. 20201

General Services Administration

Washington, D.C. 20407

13. Type of Report & Period

Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

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

bibliography or literature survey, mention it here.) Results of an interlaboratory evaluation of the ASTM E 84 tunnel test method

involving eleven laboratories and nine materials, including four carpets, are reported. Data on flame spread, smoke, and' fuel contribution are analyzed

statistically. Selected physical characteristics of each tunnel are tabulated and

compared relative to specifications in the test method. The between-laboratory

coefficient of variation (reproducibility) in flame spread classification (FSC) V7as found to range from 7 to 29% for the four carpets and from 18 to 43% for the other

j materials tested. The betvreen-laboratory coefficients of variation for smoke

developed and fuel contribution ranged from 34 to 85% and from 22 to 117% res^^ectively!

for all materials tested. The causes of higher variability in smoke and fuel contribultion measurement between laboratories is not definitely known but may reasonably be

attributed to variations in tunnel construction, maintenance, and operation, in the

location of photometers, and in the mounting of thermocouples in different laboratories

Some variability of results may possibly be due to variation in test specimens.

Variation in construction and measurement techniques among tunnels may be minimized

by updating the test method standard.

17. KEY WORDS (Alphabetical order, separated by semicolons)

ASTM E 84; building materials; carpets; fire tests; flame spread tests; interlaboratcr

evaluation; round robin; statistical analysis; test method standard.

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