REFERENCE

NBS TECHNICAL NOTE 708

Interlaboratory Evaluation of

Smoke Density

Chamber

National
NATIONAL BUREAU OF STANDARDS

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n] Bureau gf S$£^t#

8 1974

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UNITED STATES DEPARTMENT OF COMMERCE

Maurice H. Stans, Secretary NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director

NBS TECHNICAL NOTE 708

ISSUED DECEMBER 1971

Nat. Bur. Stand. (U.S.), Tech. Note 708, 80 pages (Dec. 1971) CODEN: NBTNA

Interlaboratory Evaluation of Smoke Density Chamber

T. G. Lee

Building Research Division

Institute for Applied Technology U.S. National Bureau of Standards

Washington, D.C. 20234

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C, 20402.

(Order by SD Catalog No. C 13.46:708). Price 75 cents.

TABLE OF CONTENTS

Page

Abstract 1 1. Introduction 2 2. Participants 5 3. Test Procedures 5 4. Test Materila 8

5. Results 10 Summary of Values 16

6. Statistical Analysis 17 6.1 Means and Standard Deviation 17 6.2 Variability 18 6.3 Ranking of Materials 27

7. Discussion 27

7.1 Variation between Laboratories 29

7.2 Materials 29

7.3 Results 31

7.4 Possible Sources of error 34

8. Conclusion and Recommendations 34

9

.

Acknowledgment 36

10. References 36

APPENDIX I Original Data 37

APPENCIX II Test Method for Measuring the Smoke Generation of Solid

Materials 42

1

.

Scope 42

2. Significance 42

3. Summary of Method 43

4. Apparatus 44

4.1.1 Test Chamber 44

4.1.2 Radiant Heat Furnace 45

4.1.3 Spec imen Ho lder 46

4.1.4 Framework 46

4.1.5 Photometeric System 46

4.1.6 Radiometer 47

4.1.7 Thermocouples for Determining Chamber Wall

Temperature , 47

4.1.8 Portable Recorder or Read Out Meter 47

4.1.9 Manometer for Chamber Pressure Measurements 47

4. 1. 10 Multiple Flamelet Burner 48

5. Test Specimens 48

5.1 Size 48

5.2 Specimen Orientation 48

5.3 Specimen Assembly 49

6. Specimen Conditioning 51

7. Number of Test Specimens 51

8. Test Procedure 51

9. Calculations 55

10. Report 56

in
Page

Appendix II A Calibration of Test Equipment 59

A. 1.1 Photometric System 59 A. 1.2 Radiometer 59

A. 1.3 Chamber Pressure Manometer 60

A. 1.4 Standard Smoke Generating Materials 60

Appendix II B Presentation and Use of Test Results 61

Appendix II C Construction Details 64

C.4.1.2 Radiant Heat Furnace 64

C.4.1.3 Specimen Holder 65

C.4.1.4 Support of Furnace & Specimen Holder 65

C.4.1.5 Photometric System 66

C. 4. 1.6 Radiometer 67

C.4.1.7 Chamber Wall Thermocouple 67

C.4. 1.10 Burner : 67

C.4.1.11 Pressure Regulator 68

Appendix II D Analysis of Products of Combustion 69

Appendix II E Suggested Report Form 70

Appendix II Fig. 1 Smoke Desnity Chamber 71 Fig. 2 Chamber Assembly 72 Fig. 3 Furnace Section 73

Fig. 4 Details of Speciment Holders and Burner .... 74

Fig. 5 Furnace Support 75 Fig. 6A Photometer Details 76 Fig. 6B Photometer Location 77 Fig. 7 Radiometer Details 78

IV
Interlaboratory Evaluation of Smoke

Density Chamber

T. G. Lee

Results are reported of a interlaboratory

(round- robin) evaluation of the smoke

density chamber method for measuring the

smoke generated by solid materials in

fire. A statistical analysis of the

results from 10 material-condition com- binations and 18 laboratories is presented.

For the materials tested, the median co- efficient of variation of reproducibility

was 1 .2% under non-flaming exposure

conditions and 131 under flaming exposure

conditions. A discussion of errors and

recommendations for improved procedures

based on user experience is given. A

tentative test method description is

included as an appendix.

Key Words: Building materials; fire tests;

interlaboratory tests; round-robin; optical

density; smoke; smoke density chamber;

statistical analysis.
Interlaboratory Evaluation of

Smoke Density Chamber

1. Introduction

In January 1970, an interlaboratory comparison study on the

measurement of the smoke generation characteristics of

materials was initiated by the Fire Research Section, Building

Research Division of the National Bureau of Standards (NBS)

.

ASTM Committee E-5 on Fire Tests of Materials and Constructions

acted as an advisor to the study. The goal of the study was

to evaluate the suitability of the test method for measuring

and classifying specimens of materials according to their

smoke generation potential.

A test method had been developed at NBS and reported in 196 7 by Gross, Loftus and Robertson [1]—'. It was later used to

evaluate the smoke properties of over 140 aircraft interior

materials [2] . The laboratory method measures the smoke

generation characteristic of solid specimens of given thickness under both flaming and non-flaming exposure conditions,

which represents two parameters of fire hazard. All speci2 mens are exposed to an irradiance level of 2.5 W/cm (2.2

2 Btu/sec ft ) and, in the flaming exposure, also to the flames

from a small propane-air pilot burner. In the test, smoke

from a burning specimen in an enclosed chamber is monitored

continuously by a photometer which measures the attenuation

of light caused by the smoke.

Because of the general interest in the problem of smoke and

the need for standardization of equipment, the American

—Figures in brackets indicate the literature references at

the end of this paper.
2/ Instrument Company (AMINCO) — decided to build a commercial

model of the smoke chamber. These production models became

available in the latter part of 1969; while some home-built

units were made earlier.

In late 1969, NBS circulated a proposed test method to all

known users of the Smoke Density Chamber for comments. Many

constructive suggestions were received and were incorporated

in a revised draft of the test method. All laboratories

having a Smoke Density Chamber were then invited to

participate in a interlaboratory evaluation of the method.

Two samples each of two materials (pure alpha-cellulose

paper and a PVC-PVA copolymer) were distributed for a preliminary screening and general familiarization with the test

procedure. The reported results and comments indicated the

need to provide better alighment of the burner in the flaming

exposure; and to correct for smoke deposits on the windows

of the photometer. The results of these initial studies were

considered reasonable for tests of this type.

A meeting, attended by representatives from some of the

participating laboratories in the round-robin was held to

discuss the preliminary test results and test procedures.

A more comprehensive interlaboratory evaluation of the test

method followed.

The test results from the 22 participating laboratories are summarized in this report. A statistical analysis of the

27—Certain commercial equipment, instruments, or materials

are identified in this paper in order to adequately specify

the experimental procedure. In no case does such identification imply recommendation or endorsement by the

National Bureau of Standards , nor does it imply that the

material or equipment identified is necessarily the best

available for the purpose.

3
Table 1

Participants of Inter laboratory Evaluation of Smoke Density Chamber.

Laboratory

Allied Chemical (Plastics Div.

)

Armstrong Cork (R&D Center)

DuPont (Engineering Test Center)

DuPont (Plastics Dept.)

Federal Aviation Adm. (NAFEC)

Forest Products Lab.

Location

Morristown, N.J.

Lancaster, Pa.

Newark, Del.

Wilmington, Del.

Representative

K. G. Smack

Z. Zabawsky

F. Thompson

J. Blair

a i • >t t J. P. Marcy Atlantic City, N.J. £ „. , . J

' E. Nicholas

Madison, Wise.

General Electric Co. (Plastics Dept.) Mt . Vernon, Ind.

General Tire & Rubber Co. Akron, Ohio

(Chemical Plastic Dept.)

Johns-Manville Research Center

Koppers Co. , Inc.

Lawrence Radiation Laboratory

Mobay Chemical Co.

National Bureau of Standards

National Research Council (Canada)

Olin (Research Center)

Owens Corning Fiberglas Corp.

Union Carbide (Plastics Dept.)

Uniroyal Inc. (Research Center)

Uniroyal Inc.

Rohm & Haas Co. (Redstone Res. Lab.)

Underwriters Laboratory, Inc.

Weyerhaeuser Co.

Manville, N.J.

Monroeville, Pa.

Livermore, Calif,

Pittsburgh, Pa.

Gaithersburg, Md,

Ottawa, Canada

New Haven, Conn.

Granville, Ohio

H. W. Eickner

J. Brenden

C. Bialous

G. Wear

E. Davis

C. Dzik

J. Gaskill

R. Hagins

T. Lee

J. McGuire

A. Cianciola

P. Hays

S.Charlestown, W.Va. C. Hilado

Wayne, N.J.

Mishawaka, Ind.

Huntsville, Ala.

Northbrook, 111,

Longview, Wash.

M. Jacobs

G. Jablonski

T. Pratt

J. Thiel

D. Crawford
data and comments on possible sources of errors are also

included.

2 . Participants

A total of 22 laboratories, three with home-built and 19

with commercial chambers participated in the study. The

list is given in Table 1. The laboratories are identified

in the report by code letters only. The cooperation , comments and suggestions from the participating laboratories,

are gratefully acknowledged.

3. Test Procedures

Detail test procedures were supplied to the participants in

a tentative test method standard. Slight modification in

procedures were subsequently (after the test) made/ but

these are not expected to appreciably change the precision

estimate based on the reported results. The latest version

of the test method standard is given in Appendix II.

Supplementary notes, instructions, data sheets, and a total

of 26 specimens were distributed to the participants after

they reported their preliminary test results.

There were a total of 8 materials and 10 test conditions.

Two materials were tested under both flaming and non-flaming

conditions. The instructions requested that duplicate tests

be performed for each of the test conditions , and an additional six replicates for one designated test condition.

This arrangement was selected to permit good statistical

estimates to be made of (within- laboratory) repeatability

and (between- laboratory) reproducibility with a reasonably

small number of tests.
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Table 3 Test Materials —

a/

Material Thickness Density

3 3 inch lb/ft g/cm

Color Description

Linoleum 0.125 87 1.4 Green "battleship" linoleum with burlap backing

Polypropylene 0.22 Rug

17 0.28 Light Brown

Twist, loop weave, burlap backing

Red Oak 0.25 43 0.69 Natural Uniform grain, wood, smooth finish

ABS 0.022 66 1.05 Cream Rigid plastic

opaque

oz-cellulose 0.030 41 0.66 White Pure cotton linter matting, (blotter paper)

PVC -Gypsum PVC veneer 0.010 Paper (S) 0.015 Gypsum 0.5

51 0.82 Dark PVC Veneer, simulating Brown wood grain over gypsum board

Acoustic ceiling

tile 0.75 20 0.32 Painted White

Mineral type, random and irregular shaped holes

Polystyrene Foam

PVA/PVC

ABS

1.03 1.8 0.03

0.047 75 1.2 0.032 66 1.05

Blue

Brown

Cream

Rigid low density

insulating foam, fire retardant treated Flexible

Rigid Plastic

—' All specimens were 3x3 inches
The experimental design is shown in Table 2. It was suggested that tests be made in random order, but some laboratories tested duplicates in sequence. A few did not

condition the specimens to moisture equilibrium prior to

tests because of the lack of facility or time.

Some laboratories used the previously suggested flowmeter

settings based on an air to fuel ratio of 3 to 1, for their

pilot burners; whereas the procedure had been modified to

3 3 require a ratio of 10 to 1 (500 cm /min air and 50 cm /min

propane) . This discrepancy introduced a relatively large

systematic error in the flaming results in those laboratories.

4. Test Material

The materials selected (Table 3) represent common interior

finish and construction materials, including simple and

composite plastic, cellulosic and inorganic-base materials

with thickness ranging from 0.022 to 1.03 in (0.5 to 26 mm).

These materials exhibit different forms of physical response

to fire exposure: such as slow melting, fast shrinking, rapid

decomposition and nearly non-reactive. The smoke levels from

the materials span the full range of the test instrument as well as a very narrow region to show the degree of resolution.

Most materials were obtained from commercial sources without

special controls on uniformity. All the specimens were cut

and randomized before distribution. Because of an unanticipated addition of laboratories to the study, a second batch

of some materials were prepared.

Since small quantities of fillers, pigments and additives,

and other chemical and physical properties affect the smoke

potential of materials, it should not be assumed that all

materials of the same generic type, density, and thickness

will produce the same quantity of smoke under the same conditions. 8
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5 . Results

Table 4 lists the relevant test conditions under which each

laboratory performed the tests.

The data on lamp voltage were based on the mid-range sensitivity setting of 25 and were recorded by AMINCO during the

check-out tests. A voltage of 4± 0.2 volts ac or dc has

since been adopted in the revised test method following

completion of this study.

Flowmeter settings and burner-to-specimen distances were

that reported by the individual laboratory. Laboratories

with flowmeter settings much above 30 mm (steel ball) or 75 mm (plastic ball) inadvertently used propane at a higher

than required rate.

Because of its shorter service life, the 6-hole tee burner

was replaced with a heavier 6-tube burner of similar flaming

characteristics on chambers originally shipped in the spring

of 1970. As a result, both types of burners were used in

the flaming tests. In addition to this, a modified specimen

holder with trough and burner with flamelets pointing in

three directions were distributed to test participants for use only in the flaming test on the polystyrene sample.

This holder and burner combination retains the melted portion

of the specimen under test and exposes it directly to the

burner flamelets. The modified burner and holder were

subsequently used by 12 laboratories to evaluate the 0.032

in. ABS (acrylonitrile butadiene styrene) specimens. It has

since been adopted in the revised test method for all flaming

tests

.

10
TABLE 5 Mean Dm (corr.) For Each Material and Laboratory

LAB. LINOLEUM POLY. RUG RED OAK ABS

B 748.5 739.5 548.0 201.0

D 703.

629.5 513.0 201.0

EE 783. b 663. 5 555.5 202.5

F 790.0 613.0 624.0 206.5

G 704.5 580.0 524.0 146.5

H 681.0 590.0 574 . 157.5

I 728.5 597.5 502. 192.5

J 737.5 701.5 595.0 175.5

K 719.5 586.0 57o.0 179.0

L 602.0 .656.0 622.5 226.0

M 604.5 5ti2.0 550.0 202.5

N 743.5 501.5 495.0 205.5

674.5 616.0 601.5 197.0

00 690.5 629.0 514.0 170.0

P 722.0 603.5 51d.O 162.0

R 718.5 617.5 544.5 177.5

S 776.0 668.5 558.5 198.0

LL 566.0 564.0 538.5 182.0

Q 480.0 449.5 381.5 197.0

A 524.0 489.5 473.0 184.

C 495.5 522.0 383.0 86.5

E 560.5 484.5 491.0 131.0

POLYSTYRENE

21.0

25.5

28.0

23.0

21.5

22.5

11.0

14.5

28.5

23.5

23.0

15.5

18.5

15.0

24.0

30.0

37.0

24.5

10.0

30.0

11.0

19.5

LAB. CFLLULOSE

B 159.0

D 167.5

EE 159.5

F 165.0

G 165.0

H 157.5

I 164.5

J 169.5

K 153.5

L 157.5

M 153.5

N 162.5

O 163.5

00 160.0

p 163.0

R 159.0

S 167.5

LL 179.5

Q 162.0

A 155.0

C 150.5

E 138.0

PVC

111.5

105.5

110.5

110.0

107.0

102.5

105.0

103.0

102.5

112.0

118.0

124.5

114.0

97.0

105.5

107.5

114.5

115.0

86.0

114.5

92.0

92.0

TILE/FL.

16.5

19.0

19.5

6.5

19.5

16.5

33.0

26.5

27.0

15.0

27.5

21.0

27.0

15.0

23.0

12.5

11.5

27.5

22.0

16.0

20.5

13.0

PVC/FL.

59.0

61.0

75.5

24.5

57.0

37.5

87.5

69.0

83.0

48.5

79.0

62.0

92.5

46.0

69.0

31.0

55.0

83.0

30.5

105.0

27.0

33.0

P. STYR./FL.

273.0

353.5

326.5

405.5

322.0

418.0

428.0

334.5

377.0

409.0

406.0

433.0

425.5

416.0

435.5

486.0

418.5

376.5

406.5

355.0

421.5

22.5

11
TABLE 6

,AB. LINOLEUM

B 3.5

D 17.0

EE 3.5

F 12.5

G 14.0

H 16.0

I 10.5

J 22.0

K a.

5

L 13.5

M 13.5

N 7.0

4.5

00 .5

P 5.5

R 6.C

S 1.5

LL .5

Q 8.0

A 9.U

C 1.5

E 3.0

Mean Dc , Clear Beam Value, For Each Material and Laboratory

POLY. RUG

22.5

22.0

20.0

18.5

68.0

31.0

21.5

34.0

24.0

22.5

13.0

20.5

27.5

22.5

21.0

15.0

18.0

5'4.5 46.0

23.0

27.5

o8.0

RED OAK

.5 h.O

5.0

5.5

14.0

12.0

8.5

10.5

4.5

5.5

10.5

6.0

7.5

.0.5 o.5

o.O 4.5

2.0

4.0

4.5

o.O

A8S POLYSTYRENE

6.5 1.0

9.5 1.0

16.5 3.0

10.5 5.5

7.0 2.0

4.0 .5 7.0 .0 7.5 1.5

7.0 2.5

10.5 .5

12.0 3.0

6.0 1.5

6.5 1.5

3.5 .5 2.0 2.5

5.0 2.0

3.5 1.0

1.5 4.5

6.5 1.0

17.0 3.0

1.0 .0 8.5 1.0

.AB: CELLULOSE

B 4.5

D 4.0

EE 20.5

F 6.0

G 8.0

H 4.5

I 6.5

J 4.5

K 3.5

L 3.0

M 5.0

N 5.5

O 4.5

00 4.0

p 5.0

R 6.0

s 3.5

LL 3.5

Q 8.5

A 6.0

C 3.5

E 9.5

PVC

1.5

2.5

5.5

2.0

2.5

2.5

4.0

1.5

.5 1.0

2.0

1.5

.0.5

.5 1.0

.5

.0 1.0

2.0

1.0

1.5

TILE/FL.

.5 1.0

1.0

1.0

1.0

.5 1.0

.5

.0 1.0

1.0

1.0 2.0

.0.5 1.0

.5

.0

.0 1.0

.0

.0

VFL. P. STYR./FL

.3 23.0

1.0 25.0

.3 36.0

3.5 32.5

1.0 30.0

1.0 29.5

4.0 28.5

.5 22.0

1.0 21.0

.5 20.0

1.0 25.0

.0 23.0

3.U 21.5

.u 23.0

.0 33.0

1.5 33.0

1.0 25.5

.0 55. 5 1.0 uO.O

1.0 24.5

1.5 18.5

.0 1.0

12
TABLE 7 Mean SON . . , Smoke Obscuration Number

(5 min) For Each Material and Laboratory

LAB. LINO RljG R E A k ABS PSTYR

1220,0 208.5 240.0 36.5

l'*27,0 123.5 208.0 46,5

1536.5 151.0 184,5 37,0

1320,0 173.5 238.0 36.0

1065.5 65.5 106,0 33,0

1301.0 134.5 141,5 35.5

1268.5 103.0 240.0 21.5

1636,5 200.5 166.5 25.0

1212.° 1 05.0 187.0 43,0

14 19.5 221.0 279.0 42.0

B 706. r D 801.0

EE 706,0

F 687.5

G 428.5

H 674.0

I 593.5

J 741 .0 K 550.5

L 847.5

LL 529.0

M 780,0

N 947.5

540.5

00 345.5

p 494.5

R 713.0

s 687.0

Q 650.5

A 787.5

C 350.0

E 377.5

B 335.5

D 405.5

EE 456,5

F 415,0

G 306.0

H 378.0

I 395,5

J 51 1 .5 K 329,5

L 459.5

LL 455,5

M 431 .0

N 417. 452.0

00 326.0

p 306. 5 R 4 4.5

S 388,0

Q 315,5

A 445,0

C 2 3 4.0

E 300.0

RED 0A<

208 .5 123 > 5 151 >0 173 5 65 .5 134 >5 103 200 • 5 105 >0 221

1 16 5 155

1 86 ,5 259 5 109 5 103 5

1 25 5 103 5 70 280, 5

66. 90

1361 .0 1 16.

5

195.5 35.0

1616.0 155.0 302.5 41.0

1344,0 I86.5 251.5 30.5

1107.5 259.5 194.0 39,0

13 4 3,0 109,5 208.0 31.0

1173.5 103.5 167.0 37.0

1454.0 125.5 174.0 41.0

1 299.5 103,5 171,0 39,0 "7.5 70, 230,5 35.0

1612,5 280.5 297.0 45.0

1128.0 66,0 120.0 27.0

I'll. 90,0 127.5 20.5

LAB. A CELL PVC TILE/FL

301.5 34.5

266.5 50.5

307.0 56.0

287,0 8,0

175.5 46,5

259.5 35,5

253.5 73.5

301,0 90.5

213.5 61.0

319.0 30.0

264.0 70.0

327,0 56.0

291.5 25.0

309.0 43.5

216.5 32.0

270.5 59.5

280.0 26.0

258.5 28.5

216.5 86.5

369.0 58.0

188,0 26.0

194.0 23.5

13

PVC/FL. P. STYR./FI

1 94.5 5 9 9,0

2 11.0 567,0

251,5 350.5

114.0 12/3,0

186.5 4 9 0,0

134.5 731.0

297,0 501 ,5 265.5 1000.0

270.5 324,0

170.0 887,0

260.0 95,0

292.5 233.0

130.0 657,0

1 39.0 3 7 4.5

1 4A.5 225,5

226.0 166.0

127.0 1348.0

197.0 871,0

112.0 948,5

3 9 3.0 4 13.5 116.0 1101,5

115.5 44.5
TABLE & Mean T_„ For Each Material and Laboratory

LAB. i_iiMULEt>

B 9. BO b.OU 9.Q5 12. 85 14.00

D i1 ' i5 4 ' 3 'J 10.r,5 13.80 11.65

EE 9.oU

F ii.15

G ±3.65 b.3u 13.80 16.30 12.50

H 9,u0 5.50 H.65 14.50 14.75

I 11. oU 5.65 11.05 14.25 14.50

J 9.7U 5.40 g.20 13 . 25 15. 70

K luob o.75 11.55 13.95 16.85

L 7.70

B 5.55

D 5.05

EE 4.60

F 4.80

G 5.80

H 5.15

I 5.25

J 4.35

K 5.20

L 4.35

LL 5.00

M 4.50

N 5.15

4.70

00 6.65

P 5.75

R 6.10

S 4.95

Q 5.90

A 4.40

C 5.90

E 5.60

POLY. 1 }iJo

b .00

4 .30

5 .40

5 .50

D • 3u

5 .50

5 .65

5 .40

5 .75

5..65

4,.95

4,.30

4,,5j

D , ,75

3 1 ,65

5,,6b

5 c ,15

5,,85

4c,35

3,,40

5. 15

5..10

LL 8. 80 4.95 10.75 14.00 14.25 M b.oo 4.30 10.45 11.70 16.50

N / '="J 4 ' blJ 10.75 13.50 15.35

9 ' 9 ° D ' 7 5 9.15 14.65 12.15

00 13.40 3.65 12.10 14.10 13.45

l<+.25 16.15

14.45 16.80

P 10. 2U

R 7.95

S 8. 75

Q

A

7 ' ob ^'3j 13.25 13.55 'w? fo.bO

14.65 17.35

13.55 5.55

11.70 22.50

t'

>,0U 5,1 '> 15.20 11.60 11.95

E i0 ' uu 5.10 12.00 16.00 23.00

RED 1OAK

9 .95

10 .f,5 10 .70 10 .05

13 .80

11 .65

U .05

9 .20

11,.55

9,.25

10,,75

10,,45

10;,75

9.,15

12.,10 11.,10 11.,40 11.,35

13.,25

8. 75

15. 20

1?. 00

5.30 8.50

5.90 7.75

5.30 7.00

5.35 8.75

7.55 9.00

5.25 8.75

6.30 8.50

5.00 6.45

5.80 9.05

4.90 8.20

5.95 6.70

5.45 8.25

5.15 12.65

5.05 10.25

6.10 8.85

5.35 9.05

5.65 7.35

5.90 7.05

5.5F 4.00

4.65 5.50

6.60 8.80

6.50 14.50

A3S POLYSTYRENE

14.80 14.75

13.50 17.00

12.90 15.85

LAB. CELLULOSE PVC TILE/FL. PVC/FL. P. STYR./FL.

4..C0 b.55

4.15 5.50

3.90 6.60

3.50 4.25

4.30 6.05

4. 35 5.25

4.00 b.70

3. JO 5.65

4.10 6.90

4.15 4.85

4.^3 li.00

3.75 b.75

4. 00 5.65

7.10 6.75

4.50 7.3J

4. 4 J 5.95

3.3b 4.50

3.9U 4. 85

3.9o 4.25

3. 45 b. 5b

3.7li 4. .15 4. in 10.65

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16
The mean values based on duplicate determinations of

Dm (corr.) - the maximum specific optical density

of smoke

deposit.

smoke, corrected for window

T n _ - the time to reach 90% of D . .9D m

m

D„ - the specific optical density of

photometer window smoke deposit. c

SON.-* - a smoke obscuration number based on

the smoke buildup during the first

5 minutes. (See Appendix II-B)

3/ are shown in Tables 5, 6, 7, and 8 respectively.—'

Individual values are tabulated in Appendix I. On materials

in which a laboratory performed 8 replicate tests, only the

first 2 test results are included in these summary tables.

The remaining 6 test results , including the mean and standard

deviation are tabulated in Table 9.

6. Statistical Analysis

6.1 Means and Standard Deviation

Table 10 summarizes, for each material, the arithmetic mean,

standard deviation, and coefficient of variation of data

from 18 laboratories using the AMINCO-built chamber. The

within-laboratory standard deviations are computed from the

formula: . S =

2k J-

(Xli " X

2i }

where S is the pooled standard deviation, X.. and X_ . are

37

—See Appendix II (Appendix B ) for definition of terms.

17
the replicate test results from laboratory i, and k = 18 is

the number of laboratories. The between- laboratory standard

deviations are computed from the means of the duplicates of

these 18 laboratories. The mean and between-laboratory

standard deviation of T __, , D and SON. c

. are also included.

.9D c (5)

Results of one AMINCO (Q) and all three home-built (A,C,E)

chambers are not included in the analysis. (There were

basic differences between individual home-built chambers,

and between these chambers and the AMINCO-built chambers,

e.g. chamber wall construction, photometer, etc.) A com- parison of the within-laboratory standard deviation in

Table 10 with their counterpart in Table 9 for the various

materials substantiate the assumption that laboratories

using AMINCO chambers have approximately equal precision.

6.2 Variability

A simple graphical procedure, known as the Youden Plot, was

used for comparing inter laboratory results [3] . A graph is

prepared by plotting the value of D (corr.) for one material

on the X-axis and that for another material of about the same value on the Y-axis. Each point represents one laboratory

and there will be as many points as there are reporting

laboratories. A line parallel to the X-axis is drawn

through the median of these points in the Y direction; a line parallel to the Y-axis is drawn through the median of

these points in the X direction. The two lines divide the

graph into four quadrants

.

If only random errors are present, the points can be expected

to be equally distributed in all quadrants. Points tend to

be concentrated in the upper right and lower left quadrants

when systematic bias by individual laboratory exists.

18
(jj03)ujq '6ny au9|Xdojd^|Od

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20
Figure 1 is a Youden Plot based on non-flaming test data -for

Linoleum and Polypropylene rug, and Figure 2 for the flaming

test data on PVC-gypsum board and Acoustic Tile. In both

figures, Labs A, C, E and Q are identified but are not

included in determining the medians. Figure 1 is representative of the other Youden plots for materials tested under

the non-flaming condition, and Figure 2 for the flaming

condition. There is a general tendency for points to

concentrate in the upper right and lower left quadrants

,

which is typical for most interlaboratory data. The data,

particularly in Figure 2 show that laboratories have a much

greater tendency to have similar results (high or low) on both materials thus indicating a systematic deviation which

requires explanation.

Figures 3 and 4 are another form of Youden plot in which the

first and second (duplicate) test results for a single

material are plotted. If there were no systematic biases,

about 90% of the points should be within a circle whose

radius is 2.15 times the standard deviation.

Analysis of Table I -1 (Appendix I) shows that for all materials

with D (corr.) values^lOO , 80% of all the individual values

were within ±10% of the mean values for all laboratories; also over 95 percent of all the individual values were within

±20% of the mean values for all laboratories.

An overall distribution of results (18 AMINCO chambers) is

shown in Figure 5 and 6. Deviation from the mean values of

D (corr.) for each laboratory are plotted against the mean

of all laboratories

.

21
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Points with the same values are plotted adjacent to each other

400 600

Mean Dm(corr) of All Labs.

800

FIG. 5 Mean D . .of All Labs vs. Each Lab., 4 Materials

m(corr .

)

24
300

J2> O

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cD

200

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Points with the same values are plotted adjacent to each other

100 200 300

Mean Dm(corr) of All Labs.

FIG. 6 Mean D , . of All Labs vs. Each Lab., 5 Materials

m(corr.)

25
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26
6.3 Ranking of Materials

Of the 10 material-conditions included in the tests, all

18 laboratories with AMINCO chambers ranked 9 of the

material-conditions in the same order in terms of D (corr.)

m

with only 3 reversal, see Table 11. Because of the proximity

of results between the 10th material, Acoustic tile. D

m

(corr.) =20; and the 9th material, Polystyrene Foam, non- flaming D (corr.) =23, some reversal in ranking order

occurred. This was not unexpected because of the closeness

of the D values

.

m

Table 12 shows the ranking order of the laboratories for

each material and the ranking sums (score) for each laboratory. A ranking order of 10, for example, means that the

particular laboratory has a D (corr.) value higher than

nine other laboratories for that material. The score for a laboratory is based on the sum of the rankings for all

materials [4] . The score rank indicate the ranking of the

score.

7. Discussion

This round robin was designed to examine the level of

variability of the test method for materials with a wide

range of properties in terms of composition, thickness,

reaction to heat and flame, and production of smoke. It

also included diverse types of laboratories - research as well as testing oriented; experienced as well as new to

smoke measurement work. The result should reflect therefore,

a conservative estimate of the precision of the test method.

An interlaboratory test of this type indicates clearly to

the participating laboratories who have reported systematic

27
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28
deviations from the average, that they should examine their

procedures more carefully to locate sources of such departures .

7.1 Variation Between Laboratories

The optical system and the thermal properties of the inside

walls differ between the home-built (Labs. A, C, and E) and

AMINCO chambers. As a group, the results of home-built

chambers are lower than the AMINCO type with the difference

more pronounced at the higher end of the scale.

The mean values of 5 of the 10 material-conditions supplied

by Lab. Q were the lowest of all 22 laboratories. In many

cases, Lab. Q deviations from the median exceeded 3 times

the standard deviation, and their results have been excluded,

Justifiable reruns, and withdrawal of some data by request,

based on acknowledged error, were few and are listed in

Table 13.

7.2 Materials

The materials selected for the tests covered a wide range of

smoke levels as well as physical properties. Table 9 and 10

reflect the fact that the uncertainty of the test results

(in terms of computed standard deviation and coefficient of

variation) is considerably greater for materials which change

in shape and position during test exposure. For example ABS

melted gradually and flowed down away from the high irradiance center region. The Polystyrene foam melted and shrank

into the bottom of the holder rapidly where the bottom edge

shields it from further exposure.

29
Table 13 Adjustment of Data

Lab Mate rial /Condition No. of Tests Remarks

Polystrene/ flaming Rerun, error.

Ploystrene/ flaming Rerun requested by lab.

Linoleum/non- flaming Replaced 2nd by 4th run.

PVC/flaming Not reported; assumed 62.

00 Tile/flaming Excluded, error

LL Linoleum/non- flaming

Rug/non- flaming

Red Oak/non- flaming

Withdrew Requested by

Lab . (error) . ,,

A,C,E

All

All

All Not used in statistical

calculation (excessive

variability)

All Not used; limited only

to AMINCO chamber

30
The results of the D (corr.) values show that the ratio of

m

between- laboratory standard deviation (reproducibility) , to

the within- laboratory standard deviation, range between 0.9

and 2.2. This implies that variations in procedures among

laboratories account for most of the error rather than

specimen variations. Hence, the averaging of three replicate determinations as specified in the proposed test method

standard will not improve the between-laboratory variability,

unless some of the major systematic sources of error are

removed. However, the required three determinations may

help in getting a more representative cross-section of the

material.

In terms of ranking materials based on smoke level, these

tests show (a) almost total agreement among the laboratories,

and (b) the ability to rank order consistently two materials

whose smoke density values were within 12% of each other

(Polypropylene rug = 621 versus Red oak = 552)

.

7.3 Results

As indicated by the D (corr.) values in Table 10 under the

m

non-flaming exposure condition, the five non-melting materials

have a maximum coefficient of variation of 8.4%. The other

two materials which melt, ABS and Polystyrene, have coefficients of variation of 11 and 27% respectively. However,

the 27% coefficient of variation represents a standard

deviation of only 6.3.

Under flaming exposure, the large coefficient of variation

for tile and PVC-gypsum veneer may be attributed to systematic error. In Figure 2, the high values of Lab. I and LL

and the low values of F, R, and H may be the result of using

31
Table 14 Results of Pre-Round-Robfn and Candidate Reference Specimens

Lab g(-Cellulose

Dm Dc

A 163 7 161 7 B 171 2 153 8 C 166 5 163 7 D 161 5

E 160 10

161 16 F 174 5 175 5 G 166 3 176 3 H 160 3 165 5 I 161 4 157 3 K 150

162 L 163 2 156 3 LL 164 9 169 8 M 157 6 166 7 00

156 4 162 5 p 162 6 176 2 Q 175 2 160 2 R 162 9 163 10

S 166 5 162 4 u

Between Lab Mean 163.6

S.D, 4.8

Coef .Var7„ 2.9

With in Lab

S.D, 6.1 Coef .Var% 3.7

PVC/PVA Flaming

Dm Dc

501 6 460 15 561 5 564 498 26 513 18 597 7 607 11 505 15 513 14 553 12 516 17 505 13 517 13 560 11 592 12 581 5 597 9 550

543

549 8 608 12 513 14 523 11 620 18 629 13

545 7 568 6 549 14

541 14 531 20 606 19 495 7 535 9

548.4

38.9

7.1

22.0 4.0

ABS/32 mil Flaming *J

Dm(corr) Dc

433 44010

25

(EE) 452 22 437 18 487 24 491 24

(J)435 23 475 27 488 26 453 19 462 20 457 18

439 26 440 17 420 18 471 16 469 25 474 27 426 54(32) b/ 455 58(36)

439 26 417 27 415 20

462 22

451,.4 17. 3

3. 8

20. 4

4. 5

a/ Modified Burner and Trough Holder

b/ Values in parentesis were used to calculate Dm(corr)

32
improper fuel flow rate and burner distance, (See Table 4).

If these data were excluded, the coefficient of variation

for the two materials would be reduced by about one-third.

However, for the tile and the PVC-gypsum materials, the

actual values of the standard deviation are 6.9 and 19

respectively, representing low absolute variations for low

smoke producing materials. The result for Polystyrene under

flaming exposure is less affected by variations in burner

location and fuel, since once ignited, it becomes strongly

exothermic and burns without requiring external energy.

This is also true with the thicker PVC-PVA sheet under

flaming exposure used in the preliminary tests and the

0.032" ABS sheet used in the post-round-robin tests. There,

the coefficient of variation was only 7.1% (mean D (corr.) m

= 548) and 4.5% (mean D (corr.) = 458) for the two materials

m

respectively

.

In order to detect possible gross errors in procedure or equipment, a short series of tests was conducted prior to the

round-robin on two materials. The data are shown in Table 14

Also included are results of tests performed after the roundrobin on a candidate reference material (ABS) . The unusually

high D values on ABS for Lab. Q were attributed to the

additional smoke deposited on the window during an excessive

exposure time after a maximum smoke level has been reached.

A D correction of 22 was arbitrarily subtracted from the

c reported values. The statistical results from these tests

are summarized in Table 10.

Of all the parameters listed in Table 10, the D values,

c photometer window deposit, has a relatively higher betweenlaboratory variance; which appears to be systematic. This

may have been caused by the differences in window temperature

among chambers and/or improper procedure (e.g. failure to remove the specimen from the front of the furnaces within

one minute after teaching the minimum transmittance)

.

33
7.4 Possible Sources of Error

For the materials tested in this study, there was greater

variability in the flaming exposure test results compared

to the non-flaming tests. There are several possible

sources for systematic errors in the flaming test, these

include

1. Type of pilot burner.

2. Position of the pilot burner relative to the

specimen surface (horizontal and vertical

spacings)

3. Flow rates of propane and air to the pilot burner,

8. Conclusions and Recommendations

This interlaboratory study of the smoke density chamber

test method showed that reproducible test results were

attainable for a wide variety of materials tested under

flaming and non-flaming exposure conditions.

To improve reproducibility and repeatability even further,

and to reduce systematic errors , certain features of the

test method description, apparatus and/or experimental

procedures may be noted

1. For flaming exposure conditions, a reference

standard material with a maximum specific optical

density in the range of 400 to 500 appears useful.

2. Care should be taken in the proper location and

use of the standard pilot burner to ensure its

identical re-positioning from test to test.

3. Propane and air flowmeters of the proper range

34
and calibration should be used and maintained.

4. The modified six-tube burner and holder (used on melting specimens) should be adopted for all

flaming specimens. This would simplify procedures

and avoid the need of selecting from two burners.

5. A properly calibrated radiometer should be used

and carefully maintained.

6

.

Checks should be made of the proper furnace

voltage prior to each test. In case where line

voltage fluctuation causes excessive variation

of irradiance, a constant voltage transformer

may be necessary.

7. The specified temperature limits of the wall

surface should be observed.

8. Proper conditioning of all specimens is necessary.

9. Improved specification and/or design of the

photometer window heater should minimize temperature and smoke deposit variability among the

chamber windows

.

10. Remove the specimen and commence smoke exhaust

one minute after reading maximum smoke value in

order to reduce photometer window deposit.

11. Care should be exercised when changing optical

filters, to avoid measurement errors. A system

where filter changes can be made without removal

of the optical drawer is recommended.

Recommendations 1 and 4 have since been included in the

revised test method. An effective method for changing

filters, as per Recommendation 11, is now available from

AMINCO

.

35
9 . Acknowledgment

I would like to thank all participating laboratories and

their representatives for their helpful comments, and

cooperation in making this joint study possible; the

participants for attending the pre-test conference; Mr. John

Brendan of the U. S. Forest Products Laboratory for providing

the red oak specimens; and Dr. H. H. Ku (NBS) for advice on

the statistical design and analysis.

10 . References

[1] D. Gross, J. J. Loftus and A. F. Robertson, "Method for

Measuring Smoke from Burning Materials", ASTM Special

Technical Publication No. 422 (1967)

.

[2] D. Gross, et al , Smoke and Gas Produced by Burning

Aircraft Interior Materials, Nat. Bur. Stand. (U.S.), Bldg.

Sci. Ser. 18, 27 pages (Feb 1969).

[3] Youden, W. J., "Precision Measurement and Calibration,

Statistical Concept and Procedures" edited by H. H. Ku,

NBS Special Publication 300, Vol. 1, February 1969,

U. S. Government Printing Office, Washington, D. C,

20402 or Youden, W. J., Industrial Quality Control,

Vol. XV, No. 11, 1959.

[4] Youden, W. J., Ranking Laboratories by Round-Robin

Test. Materials Research and Standards 3, No. 1, 9-13

(1963)

.

36
APPENDIX I—ORIGINAL DATA

Table 1-1 lists the duplicate values of D (corr.) for all materials

and all laboratories.

Table 1-2 lists the corresponding values of T

q

Table 1-3 lists the corresponding values of SON. .

Table 1-4 lists the corresponding values of D

c

37
TABLE i-l Duplicate Values of Dm (corr)

,

Maximum Specific Optical Density, Corrected

LAB. LINOLEUM POLY . RUG

B 764. 733. 741.*'738.

D 707. 699. 633. 626.

EE 795. 772. 675. 652.

F 786. 792. 603. 623.

G 687. 722. 580. 580.

H 632. 736. 592. 588.

I 762. b95. 594. 601.

J 74<+

.

731. 739. 664.

K 704. 735. 579. 593.

L 831. 773. 656. 656.

M 608. 601. 583. 581.

N 744. 743. 498. 505.

73b. 611. 666. 576.

00 699. o82. 659. 599.

P 742. 702. 628. 589.

R 657. 780. 596. 639.

S 80b. 746. 682. 655.

LL 568. "• 564. t Q 450. 610. 446. 453.

A 52b. 520. 486. 493.

C 483. o03. 513. 531.

u 564. 557. 461. 488.

LAB. A CELLULOSE

B 164. 154.

D 168. 167.

EE 158. 161.

F 160. 170.

G 162. 168.

H 157. 153.

I 162. 167.

J 167. 172.

K 153. 154.

L 161- 154.

M 152. 155.

N 158. 167.

167. 160.

00 162. 158.

p 169. 167.

R 156. 162.

S 169. 166.

LL 184. 175.

Q 160. 164.

A 158. 152.

C 142. 159.

E 132. 144.

pvc

114. 109.

102. 109.

113. 108.

107. 113.

113. 101.

104. 101.

108. 102.

100. 106.

102. 103.

111. 113.

120. 116.

124. 125.

115. 113.

95. 99.

106. 105.

109. 106.

117. 112.

117. 113.

91. 81.

109. 120.

93. 91.

88. 96.

RED OAK

562. 534.

525. 501.

555. 556.

616. 632.

524. 524.

583. 565.

505. 499.

597. 593.

556. 596.

645. 600.

555. 545.

491. 499.

586. 617.

539. 489.

508. 524.

534. 555.

550. 567.

520. 557.

385. 378.

473. 473.

352. 414.

490. 492.

TILE/FL

.

ARS POLYSTYRENE

15. 18.

20. 18.

19. 20.

6. 7. 21. IB. 15. 18.

32. 34.

29. 24.

27. 27.

16. 14.

29. 26.

25. 17.

16. 38.

15. 15.

21. 25.

11. 14.

6. 17.

27. 28.

22. 22.

19. 13.

15. 26.

15. 11.

197. 205. 17.. 25.

197. 205. 22,, 29.

195. 210. 24,, 32.

204. 209. 26,, 20.

147. 146. 24., 19. 153. 162. 20., 25.

193. 192. 11.. 11.

192. 159. 18.. 11.

166. 192. 3u<, 27.

230. 222. 24., 23.

199. 206. 29., 17.

200. 211. Id., 13.

183. 211. 11. 26.

169. 171. 15. 15. 165. 159. 23. 25.

193. 162. 33. 27.

194. 202. 24. 50.

166. 198. 16. 31.

184. 210. 10. 10.

174. 195. 29. 31.

63. 110. 9. 13.

130. 132. 16. 21.

PVC/FL. P. STYR./FL.

57. 61. 292. 254.

59. 63. 341. 366.

7b. 73. 326. 327.

26. 23. 397. 414.

51. 63

.

327. 317.

44. 31. 408. 428.

106. 69. 459. 397.

77. 61. 263. 386.

85. 81. 372. 382.

47. 50. 414. 404.

78. 30. 416. 396.

62. 62. 465. 411.

76. 107. 421. 430.

50. 42. 419. 413.

73. 65. 398. 473.

32. 30. 519. 453.

41. 69. 422. 415.

89. 77. 340. tl3.

2b. 33. 390. 423.

108. 102. 336. 374.

2*+. 30. 391. 452.

31. 35. 21. 24.

38
B 8.0 11.1

D 7.6 8.5

EE l>*a 11.0

F 11. b io. a

G 15.3 12.0

H 8.0 10.0

I 10.7 11.3

J 9.4 10.0

K y.b 11.6

L 6.o 8.6

LL 7.o 10.0

M 6.6 6.7

N 7.b 7.5

10.8 9.0

00 14.G l2.o

P 10.4 iO.O

R 8.3 7 -£

S 6 • b 9.0

Q 6.6 8. a A 7.3 5.9

C 12.0 12.0

E 9.0 11.0

TABLE 1-2 Duplicate Values of T

.9Dm' Time (min.) at 907, of Maximum Smoke

LAB. lIMOLFU-i. HOLY. HUG RED rlAK ARS l>0i_YS T yKE.'Jl

5.9 6.1 10.0 9.9

4.3 4.3 9.8 11.5

5.4 5.4 9.8 11.6

5.5 5.5 10.3 9.8

6.3 6.3 14.3 13.3

b.5 5.5 ll.fi 11.5

5.3 6.0 10.0 12.1

5.5 5.3 9.0 9.4

5.9 5.6 11.6 11.5

5.6 5.7 9.1 9.4

4.4 5.5 11.5 ln.O

4,3 4.3 9.7 11.2

4.5 4.5 11.0 10.5

6.5 7.0 9.5 8.8

5.8 5.5 12.0 12.2

b.O 5.3 11.6 10.6

5.3 5.0 11.8 11.0

b.6 5.1 11.5 11.2

4.0 4.7 14.0 12.5

3.8 3.0 7.8 9.7

5.4 4.9 14.5 15.9

b.O 5.2 12.0 12.0

LAB. A CELLULOSE PVC TILE/FL.

9.0 8.0

8.5 7.0

6.8 7.2

8.5 9.0

9.0 9.0

8.5 9.0

8.0 9.0

6.5 6.4

9.8 8 ..3 7.0 9.4

6.7 6.7

8.0 8.5

10.3 15.0

10.0 10.5

9.2 8.5

8.1 10.0

6.9 7.8

7.9 6.2

2.5 5.5

6.0 5.0

8.0 9.6

17.0 12.0

39

B 5.7 5.4 5.4 5.2

D 4.8 5.3 5.8 6.0

EE 4.8 4.4 5.2 5.4

F b.O 4.6 5.4 5.3

G 5.8 5.8 8.3 6.8

H 5.5 4.3 5.0 ^,.5

I D.O 4.5 6.1 6.5

J 4.6 4.1 4.9 5.1

K b.O 5.4 5.8 5.8

L 4.5 4.2 4.8 '5.0

LL 5.5 4.5 5.7 6.2

M 4.6 4.4 5.7 5.2

N 4.8 5.5 6.0 4.3

O 4.6 4.8 4.3 5.8

00 7.0 6.3 6.0 6.2

P D.O 5.5 5.1 5.6

R 7.8 4.4 5.6 5.7

S 5.0 4.9 5.8 6.0

Q 5.5 6.3 5.8 5.3

A 4.7 4.1 4.6 4.7

C b.3 5.5 6.4 6.8

E b.O 5.2 o.O 7.0

12.7 13.0 10.0 18.

U

13.3 14.3 9.3 14.0

15.6 14.0 14.

G

15.5

13.0 14.0 17,0 17.0

16.3 16.3 14.

G

11.0

15.5 13.5 13.0 16.

b

15.5 13.0 16.0 13.0

12.5 14.0 17.

b

13.8

14.0 13.9 16.7 17.0

12.5 13.3 15.7 16.0

14.5 13.5 11.0 17.5

12.0 11.4 lb.

2

16.8

14.0 13.0 16. u 14.7

16.5 12.8 4.0 <i0.0 14.2 14.0 10.7 16.2

13.8 14.7 15.

o

17. u 13.9 15.0 17.0 16.6

15.2 14.1 16.

b

18.2

13.3 13.8 5.3 5.8

11.0 12.4 22.0 23.0

7.2 16.0 •J . X 20. S 17.0 15.0 20.0 26.0

PVC/FL

.

P. STYR . /FL.

4.U 4.4 5.5 5.6

4.3 4.0 b.5 5.5

3.8 4.0 7.6 5.6

3.5 3.5 4.0 4.5

4.3 4-3 6.3 5.8

4.o 4.5 6.0 4.5

4.0 3.7 b.2 5.2

2.o b.O a.

9

5.4

3.9 4. j 7.0 6.6

4.0 4.3 4.8 4.9

4.

a

4.2 9.0 13.0

3.6 3.7 7.0 6.5

4.0 4.0 4.8 6.5

4.9 9.3 8.3 5.2

4.

a

4.5 7.8 6.8

4.0 4.3 10.0 7.9

3.9 3.2 3.7 5.3

3.b 4.0 4.9 4.8

3.0 4.8 4.5 4.0

3.b 3.4 7.4 5.7

3.5 3.9 <+.6 3.7

4.b 3.7 lb.

3

12.0
TABLE 1-3 Duplicate Values of SON . . Smoke Obscuration Number (5 min)

AB. LINOLEUM

B 960, 452'

D 725, 877-

EE 854, S58«

F 636, 739«

G 325, 532«

H 717, 631 « I 726, 461 • J 819, 663*

K 628, 473"

L 999, 696"

LL 529, S29« M 748, 812*

N 9E>8, 937'

589, 492"

00 327. 364 • p 527, 462'

R 613. a i 3 • s 734, 640.

Q 751. 550«

A 665, 910«

C 283, 417'

E 4 13, 34 2 •

AB. CELLULOSE

B 326, 345,

D 445, 366.

EE 431, 482.

F 388, JM2.

G 315, 297.

H 341, 415.

I 346, 445.

J 469, 55H.

K 339, 320.

L 450, 469.

LL 428, 483.

M 421, 441 , N 435, 399.

472. 432.

00 312. 340.

p 253. 360,

R 357, 452.

S 386, 390,

Q 329. 302,

A 436, 494,

C 185, 283,

E 249, 351,

POLY. RUG RED OAK

1338. 1 102. 259, 158.

1437. 1417. 135. 112.

1579. 1494. 1*7-. 13 5. 1309. 1331. 170, 177,

1020, 1111. 61. 70,

1323. 1279, 137, 132,

1276. 1261, 1 19. 87,

1743. 1530. 200, 201 .

1 156, 1268. 100. 110,

1389. 1450. 234, 208.

1361 , 13&1 . 89, 144,

1603, 1629. 163, 147,

1383, 1305. 196. 177,

1246. 969, 260. 259.

1260, 1426. 124. 95.

1 101, 1246. 82, 125,

1353. 1555, 123, 128.

1 182, 1417. 111. 96.

887. 1 108, 78. 62,

1492, 1733. 341, 220,

1053. 1203. 82. 58.

1 120. 1 102. 94. 86,

PVC

308, 295.

253, 280.

318. 296,

283, 291,

152, 199.

261 . 258.

268, 249.

285, 317.

233. 194,

326. 312.

271. 257,

337, 317,

287. 296,

316. 302,

218, 215,

284. 257,

281 . 279.

263, 254,

220. 213.

355, 383,

192. 184,

217. 171,

TILE/FL.

31. 3«.

54, 4>,

59. 53,

e. 8. 46, 47,

32, 39.

82. 65.

22. 59.

56. 66,

35. 25.

69. 71.

66. 46.

23. 27,

29. 58,

32. 32.

61. 58.

26. 26.

12, 45.

»l» 82.

66. 50.

21. 31 , 27. 20.

AB S

214, 266.

242. 174,

112. 257.

242. 234,

112. 100,

123. 160,

207, 273,

207. 126,

173. 201,

291. 267,

184. 207.

294. 311,

281. 222,

134. 254.

206. 210.

200. 13H,

209, 139,

141 . 201

,

257. 204.

327. 267.

POLT5TYRENE

1 12,

.22*,

128,

4 33a

PVC/FL.

197.

201 . 257,

1 10,

172.

154,

355.

296,

285,

I 68.

275.

282,

130.

230,

154,

240,

131 , 160.

1 10. 401.

105.

108.

192

221

246

1 18 201 115

239

235

256

172

245

303

130

48 139

212

123

234

1 14 385

127

123

40.

41 . jo,

49,

35,

38.

21 , 24.

45,

51.

45. 25

51 . 31 29. 32 42, 36

37, 25

40. 34 49. 33 44, 3 4 35.

35.

19.

35

'11

1922

P. STYR./FL.

563, 635,

490, 64M.

108, 593,

1112. 1434,

5C1, H79,

498, 964,

378, 625,

852. 1148,

325, 323,

943. 831.

58. 132.

345, 121,

762, 552,

148, 601,

157, 294.

80. 252.

IP 6-2.. 834.

662, 880.

1026, 871.

382, 445,

841, ,362.

31. 58.

40
TABLE 1-4 Duplicate Values of Dc Photometer Window Deposit

,AB. LINOLEUM

B 1 • 6.

D 13. 2i.

EE o • 1.

F 17. 8.

G If. 14.

H 19. 14.

I ci • 13.

J 23. 21.

K o. 12.

L 14. 13.

M 12. 13.

N 3. 9. b. 3.

00 1. 0.

p 9. 2. R 7. 3.

S 2 . 1. LL i. 0.

Q y. 7. A 13. 3,

C 2. 1.

E 2. '4.

LAB. A CELLULOSE

B 4. 5.

D 5. 3.

EE 20. 21.

F 6. 6.

G 8. 8. H 3. 6.

I 7. 6.

J 4. 5. K 3. 4.

L 3. 3.

M 5. 5.

N 4. 7.

5. 4.

00 5. 3.

p 5. 5. R 5. 7.

S 3. 4. LL 7. 0.

Q 9. 8. A 7. 5.

C 6. 1. E 5. 14.

poLr. RUG

21. 24.

21. 23.

2-0. 20.

21. 16.

70. 66.

35. 27.

21. 22.

29. 39.

^6. 22.

20. 25.

13. 13.

18. 23.

25. 30.

20. 25.

15. 27.

16. 14.

20. 16.

30. 59.

48. 44.

22. 24.

36. 19.

87. 89.

PMC

1. 2.

3. 2.

6. 5. 2. 2.

2. 3. 3. 2.

5. 3.

2. 1. 0. 1.

0. 2.

2. 2.

2. 1.

0. 0.

0. 1.

1. 0.

1. 1.

0. 1.

0. 0.

1. 1. 2. 2.

1. 1.

1. 2.

RED OAK

1. 0. 9. 7.

8. 2.

6. 5. 15. 13.

11. 13.

8. 9. 11. 10.

ABS l-'OLrSTYHF.JE

4. 5.

5. 6.

12. 9. 10. 2.

9. 6.

0. 0.

0. 1. 6. 7. 10. 2. a. 1.

l. 3.

l. 7.

8. 1. 11. 5.

TILE/FL.

1. 0.

1. 1. 2. 0.

1. 1. 1. 1. 0. 1.

1. 1.

1. 0.

0. 0.

1. 1.

1. 1.

1. 1. 2. 2.

0. 0.

1. 0.

1. 1.

1. 0.

0. 0.

0. 0.

1. 1.

0. 0. 0. 0.

2. 11.

12. 7. 13. 20.

9. 12.

6. 8.

3. 5.

3. 11.

8. 7.

4. 10.

11. 10.

12. 12.

7. 5.

5. a.

2. 5.

1. 3. 6. 4.

5. 2. 2. 1. 7. 6. 14. 20.

1. 1. 8. 9.

PVC/FL.

1. 0.

1

.

1. u. 1. 2. 3.

X • 1.

i. • 1.

7. 2.

i

.

U.

1 1.

i • 0.

1. 2.

u

.

0.

U. 6.

u. 0.

J. 0.

eL • 1. d» 0.

L» • 0.

1. 1. 1. 1.

eL • 1. U. u.

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41
APPENDIX II

September 1971

TEST METHOD FOR MEASURING THE SMOKE

GENERATION CHARACTERISTICS OF SOLID MATERIALS

1. Scope

1.1 This method of test covers a procedure for measuring the

smoke generation characteristics of solid materials and

assemblies in thicknesses up to and including 1 in. (25.4 mm).

Measurement is made of the attenuation of a light beam by smoke

(suspended solid or liquid particles) accumulating within a closed chamber due to nonflaming pyrolytic decomposition and

flaming combustion. Results are expressed in terms of specific

optical density, which is derived from a geometrical factor

and the measured optical density (absorbance) , the single

measurement most characteristic of the "concentration of smoke."

The photometric scale used to measure smoke by this test

method is similar to the optical density scale for human

vision.

2. Significance

2.1 This method provides a means for comparing the smoke

generated by materials and assemblies of given thickness and

properties under the specified exposure conditions. The

values determined by this test are specific to the material

as tested and are not to be considered inherent, fundamental

NOTE 1 - The values stated in U.S. customary units are to be

regarded as the standard. The metric equivalents of

U.S. customary units given in the standard may be

approximate.

42
properties. Correlation with other fire conditions or with

measurements by other test methods has not been established.*

3. Summary of Method3.1 This method for measuring the smoke generation characteristics of materials employs an electrically-heated radiant

energy source mounted within an insulated ceramic tube and

positioned so as to produce an irradiance level of 2.2 Btu/sec

2 2 ft (2.5 W/cm ) averaged over the central 1.5 in. (38.1 mm)

diameter area of a vertically mounted specimen facing the

radiant heater. The nominal 3 by 3 in. (76.2 by 76.2 mm)

specimen is mounted within a holder which exposes an area measuring 2 9/16 by 2 9/16 in. (65.1 by 65.1 mm). The holder

can accommodate specimens up to 1 in. (2 5.4 mm) thick. This

exposure provides the nonflaming condition of the test.

3.2 For the flaming condition, a six-tube burner is used to

apply a row of equidistant premixed (air-propane) flamelets

across the lower edge of the exposed specimen area. This

application of flame in addition to the specified irradiance

level from the heating element constitutes the flaming com- bustion exposure.

* Other test methods for measuring smoke have been reviewed

and summarized in "The Control of Smoke in Building Fires - A State-of-the-Art Review," Materials Research and Standards,

pp. 16-23, 42, April 1971.

-'D. Gross, J. J. Loftus and A. F. Robertson, "Method for

Measuring Smoke from Burning Materials," ASTM Special

Technical Publication No. 422 (1967), describes factors in

the development of this method and provides comparative test

data on the measurement of the smoke generating characteristics of materials.

43
3.3 The test specimens are exposed to the flaming and non3 3 flaming conditions within a closed 18 ft (0.51 m ) chamber.

A photometric system with a 36 in. (914 mm) vertical light

path measures the continuous decrease in light transmission

as smoke accumulates.

3.4 Calibration procedures for the test equipment as described

in Appendix A shall be followed. The light transmittance

measurements are used to express the smoke generation

characteristics of the test materials in terms of the specific

optical density during the time period to reach the maximum

value.

4. Apparatus

4.1 The apparatus shall be essentially as shown in Figs. 1 and 2. A more detailed description of suggested details (using

the same paragraph numbers) is given in Appendix C. The

apparatus shall include the following:

4.1.1 Test Chamber - As shown in Fig. 2, the test chamber

3 shall be fabricated from laminated panels to provide inside

dimensions of 36 by 24 by 36 in. ± 1/8 in. (914 by 610 by

914 ± 3 mm) for width, depth and height, respectively. The

2/—Additional parameters, such as the maximum rate of smoke

accumulation, time to a fixed optical density level, or a smoke obscuration index may be more appropriate in

particular situations. See Appendix B.

3/—Commercially available panels of porcelain-enameled steel

(interior surface) permanently laminated to asbestos-cement

board and backed with galvanized steel (exterior surface)

,

total thickness 3/16 in., has been found suitable.

44
interior surfaces shall consist of porcelain-enameled metal,

or equivalent coated metal resistant to chemical attack and

corrosion, and suitable for periodic cleaning. Sealed openings shall be provided to accommodate a vertical photometer,

power and signal connectors, air and gas supply tubes, an exhaust blower, inlet and exhaust vents, pressure and gas

sampling taps, a pressure relief valve, a rod for remote

positioning of the specimen holder, an aluminum foil (0.0010 in.

approx. 0.025 mm or less) safety blowout panel, at least

2 2 125 in. (806 cm ) in area, and a hinged front mounted door

with an observation port or window. All openings except the

gas sampling taps, the positioning rod, and an inlet vent

shall be located on the floor of the chamber. When all openings are closed the chamber shall be capable of developing and

maintaining positive pressure during test periods, in accordance

with paragraph 8.10.

4.1,2 Radiant Heat Furnace - As shown in Fig. 3 an electric

furnace with a 3 in (76.2 mm) diameter opening shall be used

to provide a constant irradiance on the specimen surface. The

furnace is to be located centrally along the long axis of the

chamber with the opening facing toward and about 12 in. (305 mm)

from the right wall. The centerline of the furnace shall be

about 7 3/4 in. (195 mm) above the chamber floor.

The furnace control system shall maintain the required

irradiance level under steady-state conditions with the chamber

door closed to within ± .04 Btu/sec ft 2 (± .05 W/cm2

) for 20

minutes. The control system shall consist of an autotransformer

or alternate control device, and a voltmeter or other means

for monitoring the electrical output. Where line voltage

fluctuations are present, a constant -voltage transformer may

be required to maintain the prescribed irradiance level.

45
4.1.3 Specimen Holder - Specimen holders shall conform in

shape and dimension to that shown in Fig. 4, and be fabricated

to expose a 2 9/16 in. (65.1 by 65.1 mm) specimen area. For

flaming exposure tests, and where melting occurs in nonflaming

tests, a modified holder with trough shall be used. Also shown

in Fig. 4 are the spring and rods for retaining the specimen

within the holders.

4.1.4 Framework for Support of the Furnace and Specimen

Holder - The furnace and specimen supporting framework shall

be constructed essentially in accordance with Fig. 5.

4.1.5 Photometric System - The photometric system shall consist of a light source and photodetector , oriented vertically

to reduce variations in measurement brought about by stratification of the smoke generated by materials under test. The

system shall be shown in Fig. 6, and includes the following:

4.1.5.1 The light source shall be an incandescent lamp operated

at a fixed voltage in a circuit powered by a voltage regulating

transformer. The light source shall be mounted in a sealed

and light-tight box located below the chamber. This box

shall contain the necessary optics to provide a collimated

light beam passing vertically through the chamber.

4.1.5.2 The photodetector shall be a photomultiplier tube,

with an S-4 spectral sensitivity response and a dark current

-9

less than 10 A. A sealed box located directly opposite the

light source shall be provided to house the photodetector and

the focusing optics. A glass window shall be used to isolate

the photodetector and its optics from the interior of the

chamber.

46
4.1.6 Radiometer - The radiometer for standardizing the output of the radiant heat furnace shall be of the circular foil

4 type, the operation of which was described by Gardon . The

construction of the radiometer shall be as shown in Fig. 7.

It shall have a stainless steel reflective heat shield with

a 1 1/2 in. (38.1 mm) aperture on the front and a finned

cooler supplied with compressed air mounted on the rear to

maintain a constant body temperature of 200 ± 5 °F (93 ± 3 °C)

4.1.7 Thermocouples for Determining Chamber Wall Temperature

- A thermocouple shall be provided for determining the chamber

wall temperature prior to testing.

4.1.8 Portable Recorder or Read-Out Meter. The outputs of

the radiometer and the thermocouples shall be monitored by a suitable recorder or read-out meter. The photodetector

output shall be recorded or monitored with a potentiometer or other suitable instrument capable of measurement over a range

of 5 decades, or more. See Appendix C, paragraph C.4.1.5.

4.1.9 Manometer for Chamber Pressure Measurements - A simple

water manometer with a range up to 6 in. (152 mm) of water

shall be provided to monitor chamber pressure and leakage (see

Appendix A) . The pressure measurement point shall be through

a gas sampling hole at the top of the chamber. A simple water

column or relief valve shall be provided to permit control of

chamber pressure. (See C4.1.11)

4/— R. Gardon, "An Instrument for the Direct Measurement of

Intense Thermal Radiation, "Review of Scientific Instruments,

Vol. 24, pp. 366-370, (1953).

47
4.1.10 Multiple Flamelet Burner with Premixed Air-Propane

Fuel - For a flaming exposure test, a six-tube burner, with

construction details as shown in Fig. 4, shall be used.

The burner shall be centered in front of and parallel to the

specimen holder. The tips of the two horizontal tubes shall

be centered 1/4 in. (6.4 mm) above the holder edge and 1/4 in.

(6.4 mm) away from the specimen surface. Provision shall be

made to rotate or move the burner out of position during non- flaming exposures. A premixed air and propane (951 purity or better) test gas shall be used. The air and propane shall be

metered by calibrated rotameters and needle valves at

3 3 500 cm /min. for air and 50 cm /min. for the propane.

5. Test Specimens

5.1 Size - The test specimens shall be 3 by 3 ± .03 in. (76.2

by 76.2 ± 0.7 mm) by the intended installation thickness up to

and including 1 in. (25.4 mm) thick. Specimens provided in

thicknesses in excess of 1 in. (25.4 mm), shall be sliced to

1 in. (25.4 mm) thickness and the original (uncut) surface

tested. Multi-layer materials greater than 1 in. (25.4 mm)

thick, consisting of a core material with surface facings of

different materials shall be sliced to 1 in. (25.4 mm) thickness, and each original (uncut) surface tested separately if

required under 5.3.1.

5.2 Specimen Orientation - If visual inspection of the speci- men indicates a pronounced grain pattern, process-induced sur- face orientation, or other nonisotropic property, the specimen

shall be tested in two or more orientations. The highest smoke

density value and the test orientation shall be stated.

48
5.3 Specimen Assembly

5.3.1 The specimen shall be representative of the materials

or composite and shall be prepared in accordance with

recommended application procedures. However, flat sections

of the same thickness and composition may be supplied and

tested in place of curved, molded or specialty parts.

Substrate or core materials for the test specimens should be

the same as those for the intended application. Where a material or assembly may be exposed to a potential fire on either side, both sides should be tested.

5.3.1.1 Finish materials, including sheet laminates, tiles,

fabrics and others secured to a substrate material with

adhesive, and composite materials not attached to a substrate,

may be subject to delamination, cracking, peeling, or other

separations affecting its smoke, generating characteristics.

To evaluate these effects, supplementary tests performed on

a scored (slit) exposed surface, or on interior layers or sur- faces, may be necessary. When supplementary tests are con- ducted for this purpose, the manner of performing such

supplementary tests, and the test results, shall be included

in the report with the conventional test.

5.3.2 For comparative tests of finish materials without a normal substrate or core, and for screening purposes only, the

following procedures shall be employed:

5.3.2.1 All sheet or film materials shall be tested by the

standard procedure regardless of thickness.

5.3.2.2 Liquid film (paints, adhesives, etc.) intended for

application to combustible base materials, shall be applied

to the smooth face of 1/4 in. (6.4 mm) thick tempered hardboard,

49
nominal density 50 to 60 lb/ft 3 (0.8 to 0.97 g/cm ), using

recommended (or practical) application techniques and coverage

rates. Tests shall also be conducted on the hardboard substtate

alone and these values shall be recorded as supplemental to

the measured values for the composite specimen.

5.3.2.3 Liquid films, (paints, adhesives, etc.) intended for

application to noncombustible substrate materials, shall be

applied to the smooth face of 1/4 in. (6.4 mm) thick asbestos3 3 cement board, nominally 120 lb/ft (1.9 g/cm ) in density,

using recommended (or practical) application techniques and

coverage rates.

5.3.3 It is the intent of this test method to maintain the

prescribed exposure conditions on the specimen for the test

duration. If, duing a nonf laming exposure test, the specimen

tends to melt or drip and fall away from the specimen holder,

it shall be tested using the modified specimen holder (with

trough) designed for the flaming test.

5.3.4 Specimen Mounting

5.3.4.1 All specimens, shall be covered across the back,

along the edges, and over the front surface periphery x^ith a single sheet of aluminum foil (0.0015 ± 0.0005 in. or approximately 0.04 mm). Care shall be taken not to puncture the foil

or to introduce unnecessary wrinkles during the wrapping

operation. Fold in such a way so as to minimize losses of

melted material at the bottom of the holder. Excess foil

along the front edges should be trimmed off, after mounting.

In using the modified holder with the trough, a flap of foil

should be cut and bent forward at the spout to permit flow

from melting specimens.

50
5.3.4.2 All specimens shall be backed with a sheet of asbestos

millboard (see paragraph 4.1.3.). The specimen and its backing

shall be secured with the spring and retaining rod. A modified

"C" shape retaining rod shall be used with specimens from 5/8

to 1 in. (I. 6 to 2.5 cm) thick. Do not compress flexible

specimens below their normal thickness.

6. Specimen Conditioning

6.1 Specimens shall be predried for 24 hr. at 140 ± 5 °F

(60 ± 3 °C) and then conditioned to equilibrium (constant

weight) with an ambient temperature of 73 ± 5 °F (23 ± 3 °C)

and a relative humidity of 50 ± 5 percent.

7. Number of Test Specimens

7.1 At least three tests under flaming exposure and three

tests under nonflaming exposure shall be conducted on each

material (total of six specimens) in accordance with the

conditions described herein.

8. Test Procedure

8.1 All tests shall be conducted in a room or enclosed space

having a ambient temperature of 73 ± 5 °F (23 ± 3 °C) and

relative humidity of 50 ± 20 percent at the time of test.

8.2 Clean the chamber walls whenever periodic visual inspection indicates the need . Clean the exposed surfaces of the

glass windows separating the photodetector and light source housings from the interior of the chamber, before each test

(ethyl alcohol is generally effective) . Charred residues on

the specimen holder and horizontal rods should be removed to

avoid contamination.

—An ammoniated spray detergent, and soft scouring pads have

been found effective.

51
8.3 During the warm-up period all electric systems (furnace,

light source, photometer readout etc.) should be on; the

exhaust vent and chamber door closed; and the inlet vent

open. When the temperature on the center surface of the

back wall reaches 95 ± 4 °F (35 ± 2 °C) , the chamber is

considered to be at steady-state condition and ready for

furnace calibration or testing. To increase chamber wall

surface temperature to the stated level under adverse con- ditions, an auxiliary heater may be used; conversely, to

decrease this temperature, the exhaust blower may be used to

introduce cooler air from the laboratory. Calibrate the fur- nace output irradiance at periodic intervals according to test

experience (normally twice per test day)

A "blank" specimen holder, with the asbestos millboard backing

exposed should always be directly in front of the furnace

except when displaced to the side by (1) the specimen holder

during a test or (2) the radiometer during calibration. It

should be returned immediately to this position when testing

or calibration is completed.

8.4 During calibration, the radiometer is placed on the

horizontal rods of the furnace support framework and accurately

positioned in front of the furnace opening, by sliding and

displacing the "blank" specimen holder against the prepositioned stop. With the chamber door closed and inlet vent

opened, the compressed air supply to the radiometer cooler is

adjusted to maintain its body temperature at 200 ± 5 °C (93 °C)

The autotransformer setting is adjusted so as to obtain the

calibrated millivolt output of the radiometer corresponding

7 to a steady-state irradiance of 2.2 ± .04 Btu/sec ft (2.5

2

± .05 W/cm ) averaged over the central 1.5 in. (38.1 mm)

diameter area.

52
The recorder or meter described in paragraph 4.1.8 is used to

monitor the radiometer output. After the prescribed irradiance

level has reached steady-state, the radiometer is removed

from the chamber and replaced with the "blank" specimen holder.

8.5 After the system has reached steady-state conditions,

adjust meter and/or recorder zero. Adjust the amplifier

sensitivity to obtain a full-scale reading of the photodetector (100 percent transmittance) on the recorder or readout meter. Determine the "dark current" (zero percent transmittance) on the maximum sensitivity range of the read-out

meter by blocking the light, and adjust the "dark current"

reading to zero.

8.6 For nonf laming exposures, the multiple flamelet burner

is removed. For flaming exposures, the burner is positioned

across the lower edge of the specimen as described in paragraph

4.1.10. Check the burner distances relative to the "blank"

specimen before fuel adjustment and ignition.

8.7 Before positioning the test specimen, flush the chamber

with the door and exhaust and inlet vents open for about 2 minutes, and verify the starting temperature of the chamber,

using the procedure described in paragraph 8.3.

8.8 Close the exhaust vent and blower. Place the loaded

specimen holder on the bar support and push it into position

in front of the furnace (with burner in position for flaming

exposure) by displacing the "blank" holder. Quickly close the

chamber door and simultaneously start the timer, and/or

recorder chart drive. Close the inlet vent completely only

when the photometer indicates smoke.

53
8.9 Record light transmittance and the corresponding time

either as a continuous plot with a multi-range recorder or at

sufficient time intervals with a multi-range meter read-out.

Make and note the necessary full-scale range changes in

decade steps.

8.10 Observe the increase in chamber pressure with the

manometer described in paragraph 4.1.9. A regulator (see

C4.1.11) shall be used to maintain the pressure in the range

of 4 ± 2 in. (100 ± 50 mm) of water during most of the test.

If negative pressure develops after very intense specimen

flaming, open the inlet vent slightly to equalize the pressure.

As a result of pressure rise, the fuel and air valves must be

adjusted during the flaming test to maintain constant flow

rate.

8.11 Record any observations pertinent to the burning and

smoke generating properties of the material under test, in

accordance with paragraphs 10.1.6 and 10.1.7.

8.12 Continue the test until a minimum light transmittance

value is reached or after an exposure of 20 minutes; whichever occurs first. If desired, the test may be conducted for

periods in excess of 20 minutes, when minimum transmittance

levels have not been reached during the 20 minute exposure.

The term "Extended Exposure" is to be used to identify data

developed in tests longer than 20 minutes in duration.

8.13 If transmittance falls below 0.01%, the chamber window

should be covered with an opaque screen to avoid possible light

scattering effects from room light. Also any supplementary

optical filter in the photometer system should be removed or displaced in order to extend the measuring range. If extraneous

54
light can reflect into the photometer during removal of the

filter, turn the high voltage off or adjust the scale to

minimize sensitivity. Replace the filter before exhausting

smoke from the chamber.

8.14 Extinguish the burner on flaming exposures and start

exhausting the chamber within one minute after reaching

minimum transmittance . Displace the specimen from the front

of the furnace by pushing the "blank" specimen holder with

the positioning rod. Continue to exhaust with the inlet vent

open until maximum transmittance is reached. Record this

transmittance value as the T , "clear beam" reading which is

to be used to correct for deposits on the photometer windows.

9. Calculations

9.1 Calculate specific optical density, D , from the reduction

in light transmittance, T, caused by the smoke generated from

an exposed specimen area, A, in the closed chamber of volume,

V, and over a light path, L, as follows:

D

s = IK [lo §10 C —)] = G [lo §10 C-T-^

where G represents the geometrical factor associated with the

dimensions of the chamber and specimen.

9.2 Calculate the maximum specific optical density, D , using

the formula in paragraph 9.1 with a light transmittance corre- sponding to the minimum level reached durint the test. Correct

all maximum specific optical density Values by substracting

the specific optical density equivalent for soot and other

deposits on the photometer windows. As described in paragraph

8.14, the "clear beam" transmittance reading T is used to

55
calculate a specific optical density equivalent D , using the same formula but with different subscript. A corrected maximum

specific optical density calculation is expressed as follows:

Dm (corr.) = Dm

- D m ^ ' m c

9.3 For systems without "dark current" cancellation, a correction must be made for any light transmittance reading

T, approaching the dark current value T,. The corrected light

transmittance T

1 , is obtained from:

T. - 1 - ^

and is used for the specific optical density calculations

described in paragraphs 9.1 and 9.2.

9.4 Determine t.9D , the time for the smoke to accumulate to

m'

90 percent of the uncorrected maximum specific optical density

value from a plot of specific optical density versus time or from the tabulated data.

9.5 When the test is continued beyond the standard 20 minute

exposure, all calculations are to be made in accordance with

paragraphs 9.1 through 9.4 and the results identified as "Extended Exposure."

10. Report

10.1 The report (see Appendix E) shall include the following

10.1.1 Complete description of the material tested including

type, manufacturer, shape, thickness and/or other appropriate

dimensions, weight or density, coloring, etc.

56
10.1.2 Complete description of the test specimens, including:

substrate or core, special preparation, mounting, etc.

10.1.3 Test specimen conditioning procedure.

10.1.4 Number of specimens tested.

10.1.5 Test conditions: type of exposures, type of holder

used, exposure period.

10.1.6 Observations of the burning or smoldering characteristics

of the specimens during test exposure, such as delamination,

sagging, shrinkage, melting, collapse, etc.

10.1.7 Observations of the smoke generating properties of the

specimens during exposure, such as, color of the smoke, nature

of the settled particulate matter, etc.

10.1.8 A record of the geometrical factor, G, as calculated

from measured values of chamber volume, V, photometer light

path length, L, and exposed specimen area, A (see Section 9 on calculations).

10.1.9 Test results calculated as described in Section 9,

including the average and range on each set of specimens for

D (corr.), t gD , D and others (see Appendix B.) if

required. m

11. Precision and Accuracy

11.1 For D values above 100, the coefficient of variation

m

of measurements on a uniform sample by an individual laboratory

may range from 2 to 8 percent. For D values below 100, the

57
estimated standard deviation by an individual laboratory is

about 10 or less. For measurements among laboratories, the

coefficient of variation and standard deviation estimates may

be greater by a factor of about 1.5.

58
APPENDIX TI ~A Calibration of Test Equipment

Al.l Photometric System

Al.1.1 Calibration of the photometer is checked by interrupting the light beam with calibrated neutral density filters.

The filters should cover the full range of the instrument.

Optical density values measured by the photometer shall be

within ± 3% of the calibrated values.

Al.l. 2 Effective light beam cross-section measurements are made at the top and bottom of the chamber, by inserting an opaque sheet of material into the beam path from opposite

sides of the beam at several points, and noting the point

at which the light transmittance reading decreases. Using

these measurements, the average diameter of the sensing area

to the phototube may be determined. See C4.1.5.

Al.l. 3 Shifts in dark current levels between tests, excessive

zero shifts during test or lack of calibration indicates the

need for inspection of the photometer system.

A1.2 Radiometer

Calibration of the radiometer is accomplished by placing it

at suitable distances from a radiant energy source, while

maintaining its body temperature at 200 ± 5 °F (93 ± 3 °C)

with controlled air flow through the rear-mounted cooler, and

measuring its electrical output as a function of the irradiance level. The irradiance level is determined calorimetrically

by measuring the rate of temperature rise of a blackened thin

copper disk of known weight, area (1 1/2 in., 38.1 mm dia)

,

specific heat and absorptivity in place of the radiometer.

59
The measured millivolt output of the radiometer, at a bodytemperature of 200 °F (93 °C) , corresponding to an irradiance

level of 2.2 ± .04 Btu/sec. ft

2 (2.5 ± .05 W/cm2

) is used to

establish the furnace control settings discussed in paragraphs 4.1.2 and 8.3.

A1.3 Chamber Pressure Manometer - Leakage Rate Test

For purposes of standardization, periodically conduct a leakage rate test using the manometer and tubing described in

paragraph 4.1.9. Pressurize the chamber to 3 in. (approximately 76 mm) of water by introducing compressed air through

a gas sampling hole in the top. Time the decrease in pressure

from 3 to 2 in. (approximately 76 to 50 mm) of water with a stop watch. This time should not be less than 5.0 minutes.

A1.4 Standard Smoke Generating Materials

For checking operational and procedural details of the

equipment and method described herein, two standard materials

may be used. Under nonflaming conditions, a single layer of

nominal 0.030 in. (approximately 0.76 mm) thick alphacellulose (cotton linters) paper should provide repeatable

maximum specific optical density values of 170 ± 10; under

flaming conditions, a 0.032 in. (0.81 mm) thick plastic sheet

should provide repeatable maximum specific opticla density

values of 455 ± 15. These reference samples may be purchased

from the Office of Standard Reference Materials, National

Bureau of Standards, Washington, D.C. 20234. Use of these

standard materials does not obviate the need for following

the calibration and standardization procedure outlined in

this Standard.

60
APPENDIX ii-b

Presentation and Use of Test Results

Bl. The smoke chamber test results in a curve of specific

optical density versus time. The maximum specific optical

density, D , represents total smoke accumulation. Since the

' ' m' r time to reach this point is often indistinct, the time to

reach 90% of D , t . n , generally represents a more easily defined

and repeatable point. Additional parameters which may be of

particular value include:

R : Maximum rate of increase in specific optical

m r r density per minute, measured over a 2-min. period.

t B =16: Time to reach D = 16 (T = 75%), or other

s s smoke level.

This is a simple measure of smoke generation

rate, particularly where time is important.

Dm

501 = 2UUU H

2

= 16

Ct .3

111 - ~1 + t

.5 " t .3

+

t .7 " t .5

s

t

.9 " t.7

where t , , t ,, etc., indicate the time in

minutes at which the smoke accumulation

reaches 10, 30, etc., percent of the maximum

density D . The smoke obscuration index ' m incorporates the effects of total smoke,

generation rate and time to reach D =16.

(See footnote 1 of main text)

61
SON

4

= D

1 + D

2 + D3

+ D

4

Smoke obsuration number based on the simple

addition of the 1,2,3 and 4 minute values

of specific optical density. This index

represents a weighted rate of smoke generation

over a 4 minute interval only.

B2 . The preceding parameters are obtained for the flaming and

nonflaming exposures separately, and the highest value could

presumably be used. There may be some merit in combining

values from the flaming and nonflaming tests to yield a single composite index, e.g.

SOI c

= [(SOI) £

. (SOI) n ] 1/6

B3, A more comprehensive approach to smoke hazard evaluation

of a material might include the effects of smoke obscuration

7 under a bracketing set of fire conditions , e.g.

8 MSCU = . „ I

( SOl h

for i = 1, nonflaming test (std)

i = 2, flaming test (std)

i = 3, nonflaming test with forced ventilation

i = 4, flaming test with forced ventilation

i = 5, nonflaming test at high irradiance level

i = 6, flaming test at high irradiance level

i = 7, nonflaming test at high irradiance level and

forced ventilation

i = 8, flaming test at high irradiance level and

forced ventilation.

6/ G. Williams-Leir , Private Communications.

-'J. R. Gaskill, Fire Technology, August 1968.

62
B4 . A principal advantage of using specific optical density

is that the results can be related to (a) areas of materials

which potentially could be involved in fire, (b) distances of

light paths from observer to exitways, and (c) the volume of

enclosing space. This may be accomplished by multiplying D or D by the involved areas (flaming and nonflaming) and the

length of light path and dividing by the volume of the enclosed

AL

space, tt— . See reference (1) for a more detailed discussion.

63
APPENDIX II-C

Construction Details

(Paragraph numbers correspond to applicable paragraphs in

Section 4. Apparatus of main text).

C4.1.2 Radiant Heat Furnace

The furnace shall consist of a coiled wire or other suitable

electrical heating element (525 W or greater) mounted vertically

in a horizontal ceramic tube 3 in. (76.2 mm) i.d. by 3 3/8 in.

(85.7 mm) o.d. by 1 5/8 in. (41.3 mm) long. The tube is bored

out at one end to 3 1/32 in. (77.0 mm) i.d. and to a depth of

5/8 in. (15.9 mm) to accommodate the heating element. A 1/16

in. (1.6 mm) asbestos paper gasket, three stainless steel

reflectors are mounted behind the heating element. A 3/8 in.

(9.5 mm) asbestos millboard disc, provided with ventilation

and lead wire holes, shall be positioned behind the heating

element and used to center the assembly with respect to the

front 3/8 in. (9.5 mm) asbestos millboard ring by means of

a 6-32 stainless steel screw. The adjustment nuts on the end

of the centering screw shall provide proper spacing of the

furnace components. The cavities adjacent to the heating

element assembly shall be packed with glass wool. The furnace

assembly shall be housed in a 4 in. (102 mm) o.d. by 0.083 in.

(2.1 mm) wall by 4 1/8 in. (10.5 cm) long stainless steel tube.

Two additional 3/8 in. (9.5 mm) asbestos board spacing rings

and a rear cover of 3/8 in. (9.5 mm) asbestos board shall

complete the furnace. The furnace is to be located centrally

along the long axis of the chamber with the opening facing

toward and about 12 in. (305 mm) from the right wall. The

centerline of the furnace shall be about 7 3/4 in. (195 mm)

above the chamber floor.

64
C4.1.3 Specimen Holder

The specimen holder shall conform in shape and dimension to

Fig. 4 and be fabricated by bending and brazing (or spot welding) 0.025 in. (0.6 mm) thick stainless steel to provide a

1 1/2 in. (38.1 mm) depth, and to expose a 2 9/16 by 2 9/16 in.

(65.1 by 65.1 mm) specimen area. As described in paragraph

4.1.4, the holder shall have top and bottom guides to permit

accurate centering of the exposed specimen area in relation

to the furnace opening. A 3 by 3 in. (76.2 by 76.2 mm) sheet

of 1/2 in. (12.7 mm) asbestos millboard, having a nominal

density of 50 ± 10 lb/ft 3 (0.85 ± 0.17 g/cm3

) , shall be used

to back the specimen. A spring bent from 0.010 in. (approximately 0.25 mm) thick phosphor bronze sheet shall be used

with a steel retaining rod to securely hold the specimen and

millboard backing in position during testing.

C4.1.4 Support of Furnace and Specimen Holder

The framework as shown in Fig. 5 shall have welded to it a

5 in. (12.7 cm) o.d., 1/4 in. (6.4 mm) wall, 2 in. (50.8 mm)

long horizontally oriented steel tube to support the radiant

heat furnace described in paragraph 4.1.2. This support tube

shall have provision to accurately align the furnace opening

so that it is: (1) 1 1/2 in. (38.1 mm) away from, (2) parallel

to and (3) centered with respect to the exposed specimen area. Three tapped holes with screws equidistantly positioned around

the furnace support tube, or one screw at the top of the

support in conjunction with two adjustable (vertically along

the support tube) metal guide strips mounted horizontally

inside to the tube, shall provide adequate alignment.

The framework shall have two 3/8 in. (9.5 mm) diameter

transverse rods of stainless steel to accept the guides of

65
the specimen holder described in paragraph C4.1.3. The rods

shall support the holder so that the exposed specimen area is

parallel to the furnace opening. Spacing stops shall be

mounted at both ends of each rod to permit quick and accurate

lateral positioning of the specimen holder.

C4.1.5 Photometric System

The photometric system shall consist of a tungsten-filament

light source, (Type 1630 6.5 volt lamp, maintained at 4 ± 0.2V)

and photodetector (Type 931V-A) , oriented vertically to reduce

variations in measurement brought about by stratification of

the smoke generated by the specimens under test. The system

shall be as shoivn in Fig. 6. The window in the chamber floor

through which the light beam passes shall be provided with an electric heater to maintain a temperature of at least 125 °F

(52 °C) to minimize smoke condensation. The collimated beam

inside the chamber shall have a path length of 36 ± 1/8 in.

(914 ± 3 mm) and a sensing cross-section of 1 1/2 ± 1/8 in.

(38.1 ± 3.2 mm) diameter (see Appendix A, paragraph Al.1.2).

The approximately circular light "spot" shall be centered

entirely within the sensing area of the detector. A typical

photomultiplier photometer system will require a high-voltage

D.C. power supply and a neutral density filter of sufficient

optical density to produce a convenient signal level for the

indicator or recorder. The photometer system used shall be

capable of permitting the recording of reliable optical

densities up to 5.0, corresponding to transmittance values

of 0.001 percent of the incident light. (See Appendix A

Al.1.1).

The two optical platforms and their housings shall be kept in

alignment with three metal rods, 1/2 in. (12.7 mm) in diameter,

fastened securely into 5/16 in. (7.9 mm) thick externally

66
mounted top and bottom plates and symmetrically arranged about

the collimated light beam.

C4.1.6 Radiometer

The body temperature of the radiometer shall be monitored with

a 100-220 °F (38-100 °C) thermometer in a 1/2 by 1/2 by 1 1/2 in

long (12.7 by 12.7 by 38.1 mm) brass well drilled to accept the

thermometer with a close fit. Silicone grease may be used to

provide good thermal contact.

The circular receiving surface of the radiometer shall be

spray-coated with an infrared-absorbing black paint containing

a silicone vehicle. The radiometer shall be calibrated calorimetrically in accordance with the procedure summarized in

paragraph A1.2 of Appendix A.

C4.1.7 Chamber Wall Thermocouple

A thermocouple shall be mounted with its junction secured to

the geometric center of the inner rear wall panel of the

chamber using a 1/4 in. (6.4 mm) thick polystyrene foam disk cover and epoxy cement.

C4.1.10 Burner

The Multiple flamelet burner shall be a six-tube burner, with

construction details as shown in Fig. 4. The vertical tubes of

the six-tube burner shall be made from 1/8 in. (3.2 mm) o.d. by

0,031 in. (0.8 mm) thick-wall stainless steel tubing. All

tubes should be crimped at the tip to reduce the opening

diameter to 0.055 in (1.4 mm). The horizontal manifold section

of the burner shall consist of 1/4 in. (6.4 mm) o.d. by 0.035

in. (0.9 mm) wall stainless steel tubing. The other end is

attached to a fitting in the chamber floor.

67
C4.1.11 Chamber Pressure Regulator

A simple pressure regulator consists of an open, water-filled

bottle and a length of flexible tubing, one end of which is

connected to a sampling port on the top of the chamber. The

other end of the tubing is inserted 4 in. (10 mm) below the

water surface. The bottle is located at the same level as the

floor of the chamber.

68
APPENDIX ii-d

Analysis of Products of Combustion

Although not specifically required as a part of the method,

products of combustion may be drawn from the chamber at

various times during the progress of the test for analysis.

The physical properties of the smoke may be investigated by

electrostatic or impact collection and various methods of

particle analysis. The presence and concentrations of various

toxic and irritating gaseous products may be determined using

colorimetric gas detector tubes, gas chromatography methods,

ion-selective electrodes, or other techniques.

69
APPENDIX II -E Suggested Report Form

SMOKE DENSITY CHAMBER

Sample Code

Lab Code

Test No.

Operator_

Date

Time

Recorded Data or Curve

Time, min. 7„ Trans. , D

s o \oo o

.

Operating Conditions Radiometer Reading Furnace Voltage

mV; Irradianca_

V

W/cm

Burner Fuel cc/min air; Thermal Exposure: flaming smoldering Chamber Pressure

Chamber Wall Temp. °C Chamber Surface Condition

inch HO

_cc/min propane

Burner & Holder:

Sample

standard special

Description - Manufacturer - Preconditioning: Temp. °C; Duration

Conditioning: Temp^ °C; RH 7.; Duration

Thickness - in.; Density

Initial Wt

.

; Final Wt

.

Special Conditions -

hr.

g/cm or lb/ft

; % Loss

Results

Min. Trans. _%_ Max. Specific Optical Density, Dm Time to Reach 907, D = m

Clear Beam Reading =

D (corr.)

7„; Equiv. D

I)

Optional Presentation of Results Time to Develop D = 16 =

Max. Rate, R

dt

SON,,, . v = D. + D. + D, + D. (4 min) 12 3 4 Remarks

70
Fig. 1 SMOKE DENSITY CHAMBER

71
A - Phototube Enclosure

B - Chamber

C - Blowout Panel

D - Hinged Door with Window

E - Exhaust Vent Control

F - Radiometer Output Jack

G - Temperature (Wall) Indicator

H - Temperature Indicator Switch

I - Autotrans formers

Figure

J - Voltmeter (furnace) S K - Fuse Holders T

L - Furnace Heater Switch U M - Gas & Air Flowmeters V W - Gas & Air Shutoff Valves W

- Light Intensity Controls X

P - Light Voltage Measuring Jack Y

Q - Light Source Switch Z R - Line Switch

Smoke Density- Chamber Assembly

Support Frame Indicating Lamps Photometer Readout

Rods

Glass Window

Exhaust Vent

Inlet Vent Access Ports

72
A - STAINLESS STEEL TUBE

B - ASBESTOS BOARD

C - CERAMIC TUBE

D - HEATING ELEMENT, 525 W

E - STAINLESS STEEL SCREW

F - ASBESTOS PAPER GASKET J - ASBESTOS BOARD

G - STAINLESS STEEL SPACING K-ASBESTOS BOARD RINGS WASHERS (3) L-ASBESTOS BOARD COVER H - STAINLESS STEEL REFLECTOR M-SHEET METAL SCREWS

I

- STAINLESS STEEL REFLECTOR W-PYREX GLASS WOOL

FIG. 3 -FURNACE SECTION

73
O a> o

a.

(Si

\y^ d g £ 2

Was stag

OO tn S O o

UJ

z>m

I-3

Q.

Q

Z

<

UJQ

_J

o

I

UJo

UJ

Q_CO

u.o

en

UJo

00

7U
n

<r Sfr ^

CO

>- \ 11 UJ

x < CD ?^ 2 f o 5/ UJlO bj

«" o *:

_i -i

u

_i = < <\i

X

X CO

QQ O b co m ozu<

CLLOd

c>

cro

Q_

CL

coUJO<

-z. or

=)

1/3

75
DIFFUSER

PHOTOMULTIPLIER TUBE

i F I LTER C REMOVABLE )

* SHUTTER

nov

^*= ««-T0P OF

CHAMBER

'4DIA.STEEL RODS

—-BOTTOM OF

CHAMBER

Fig. 6A Photometer Details

76
REAR OF CHAMBER

i f

'

4'

a*

crUJ

ca<

io

b.O

~G*> J

i

1'

>'

Ui / 3" \ ~ -

'

I /

Ji'BiA- | Mem. Ro»* —

i _ (A\

< 4 {J* > 7

H

\r

PHOTOMETER LOCATION

PLAN VIEW

Fie. 6B Photometer Location

77
78
ormNBS-114A 11-71) U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS-TN 708

2. Gov't Accession No.3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Interlaboratory Evaluation of Smoke Density Chamber

5. Publication Date December, 1971

6. Performing Organization Code

7. AUTHOR(S)

Ti G. Lee

8. Performing Organization

10. Project/Task/Work Unit No. 4212229

9. PERFORMING ORGANIZATION NAME AND ADDRESS NATIONAL BUREAU OF STANDARDS DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Same

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 are reported of an interlaboratory (round-robin) evaluation of the

smoke density chamber method for measuring the smoke generated by solid

materials in fire. A statistical analysis of the results from 10 materialcondition combinations and 18 laboratories is presented. For the materials

tested, the median coefficient of variation of reproducibility was 7.2% under

non-flaming exposure conditions and 13% under flaming exposure conditions.

A discussion of errors and recommendations for improved procedures

based on user experience is given. A tentative test method description is included as an appendix.

!'• KEY WORDS (Alphabetical order, separated by semicolons) Building materials; fire tests; interlaboratory tests; uptical density; round robin;

smoke; smoke density chamber; statistical analysis.

18. AVAILABILITY STATEMENT

PH UNLIMITED.

I I FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Price

75

USCOMM-DC 66244-P7J

* U.S. GOVERNMENT PRINTING OFFICE : 1971 481-328/135

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