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NBSIR 79-1588

Interlaboratory Evaluation of

the Attic Floor Radiant Panel

Test and Smoldering

Combustion Test for Cellulose

Thermal Insulation

J. Randall Lawson

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Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, D C. 20234

February 1979

Final Report

Prepared for: Consumer Product Safety Commission

Textile and Mechanical Engineering Group

Bethesda, Maryland 20202

NBSIR 79-1588

INTERLABORATORY EVALUATION OF

THE ATTIC FLOOR RADIANT PANEL

TEST AND SMOLDERING

COMBUSTION TEST FOR CELLULOSE

THERMAL INSULATION

J. Randall Lawson

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

February 1979

Final Report

Prepared for: Consumer Product Safety Commission

Textile and Mechanical Engineering Group

Bethesda, Maryland 20202

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps. Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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TABLE OF CONTENTS

Page

LIST OF FIGURES iv

LIST OF TABLES iv

Abstract 1

1. INTRODUCTION 2

2. TEST APPARATUS AND METHODS 3 2.1 Attic Floor Radiant Panel 3 2.2 Smoldering Combustion 3

3. LABORATORY QUALIFICATION 4

4. PARTICIPANTS 5

5. MATERIALS AND SAMPLE PREPARATION 5

6. EXPERIMENTAL DESIGN 6

7. TEST RESULTS AND DISCUSSION 7 7.1 Critical Radiant Flux Test 7 7.2 Smoldering Combustion Test 9

8 . SUMMARY AND CONCLUSIONS 10

9. RECOMMENDATIONS 10

10. ACKNOWLEDGMENTS 11

11. REFERENCES 11

APPENDIX A - PARTICIPANTS IN THE INTERLABORATORY FIRE TEST PROGRAM . . A-l

APPENDIX B - STATISTICAL METHODS B-l

APPENDIX C - CELL AVERAGES AND STANDARD DEVIATIONS FOR

CRITICAL RADIANT FLUX AND SMOLDERING COMBUSTION C-l

iii
LIST OF FIGURES

Page

Figure 1. Attic floor radiant panel tester schematic - side evaluation 12

Figure 2. Standard radiant heat energy flux profile 13

Figure 3. Commercially built attic floor radiant panel 14

Figure 4. Home built attic floor radiant panel . 15

Figure 5. Smoldering combustion test (materials before testing) ... 16

Figure 6. Smoldering combustion test (materials after testing) ... 17

LIST OF TABLES

Page

Table 1. Critical radiant flux data 18

Table 2. Pass and fail tabulation (critical radiant flux) by

materials and laboratories . . . . 19

Table 3. Precision estimates of critical radiant flux measurements . 20

Table 4. Comparison of precision estimates for fire test methods . . 21

Table 5. Percent weight loss - smoldering combustion test 22

Table 6. Pass and fail tabulation (smoldering combustion) by

materials and laboratories 23

Table 7. Precision estimates of percent weight loss (smoldering

combustion) for materials without split test results .... 24

IV
INTERLABORATORY EVALUATION OF THE ATTIC FLOOR RADIANT

PANEL TEST AND SMOLDERING COMBUSTION TEST FOR

CELLULOSE THERMAL INSULATION

J. Randall Lawson

Abstract

An interlaboratory test program was conducted to

provide estimates of repeatability and reproducibility

of fire tests for cellulose loose fill insulation. The

test methods evaluated were for critical radiant flux,

using the Attic Floor Radiant Panel, and for smoldering

combustion; they were based on Federal Specification

HH-I-515D. Seven commercially manufactured cellulose

thermal insulations marketed for residential use were

evaluated by each procedure. An additional set of four

replicate hardboard specimens were tested by each participant using the Attic Floor Radiant Panel. Nine

laboratories conducted the Attic Floor Radiant Panel

test, and ten conducted tests for smoldering combustion.

The testing was conducted during the month of June 1978.

The participating laboratories were surveyed prior to

testing in order to ensure conformance to the critical

details of the test apparatus and procedures.

The between-laboratory coefficient of variation

for critical radiant flux ranged from 13 to 30 percent

with an average for seven insulation materials of 21

percent. Estimated precision levels of repeatability

and reproducibility for the Attic Floor Radiant Panel

test when compared to other standard flame spread tests

and materials are favorable. Data from the Smoldering

Combustion test was evaluated on a pass/fail basis with

agreement by nine of ten laboratories for six of the seven materials tested. Seven of ten laboratories also

agreed on the seventh material.

Based on work of this study, there is reasonable

assurance that results from different laboratories

evaluating the same material for compliance with Federal

Specification HH-I-515D will be consistent.

1
Key words: Attic floor radiant panel; cellulose

thermal insulation; critical radiant flux; flame spread;

test methods; smoldering combustion.

1. INTRODUCTION

Loose fill cellulose thermal insulation has been manufactured and used

in the United States for several decades. With the increasing need to

respond to the demand for energy conservation through reducing residential

heat losses, the industry has grown at a rapid rate. With this growth,

several problems have become apparent. As stated at the Consumer Product

Safety Commission's (CPSC) public meeting of August 22, 1977, some of these

problems were related to the fire properties of the materials. Only one fire

test method has been used by regulatory bodies to evaluate the fire properties of cellulose insulation. This is the ASTM E 84 Steiner Tunnel Test [1]^

It is apparent that the test is not designed for evaluating attic insulations

since insulation is generally exposed on an attic floor and the tunnel test

evaluates it on the ceiling. Additionally, the insulation sample must be

supported by a fine mesh screen wire which further alters the natural environ

ment. It was also recognized that the procedure did not take into account

the smoldering combustion process. A separate test method was developed for

the evaluation of this fire property. These problems with fire testing and

the fire incidence noted in Denver, Colorado and other areas resulted in the

updating of performance specifications for insulation.

The investigation of thermal insulation-related fires identified a significant fire scenario which had not been addressed. It was found that

many insulation-related fires were initiated by the overheating of recessed

light fixtures covered with insulation. The initial mode of combustion

was a slowly propagating smoldering of the insulation. In some cases the

smoldering material would involve other building materials and open flaming

would occur. A review of fire scenarios and laboratory mockup tests on insulations showed that relatively rapid flame spread on the exposed surface

of attic insulation could also be caused by ignition from open flaming

sources [2]. As a result, a new standard was written. Federal Specification

HH-I-515D which replaced HH-I-515C, and new test methods were included to

evaluate the fire properties of the materials [3]. The Attic Floor Radiant

Panel test is an adaptation of an established test method for flooring

Numbers in brackets refer to the literature references listed at the end of

this paper.

2
materials [4,5]. The Smoldering Combustion test is a newly developed test

for evaluating the tendency of thermal insulation to initiate and propagate

a smoldering reaction.

As part of the test development, an interlaboratory test program was

2 3 conducted to evaluate the repeatability and reproducibility of the Critical

Radiant Flux and Smoldering Combustion tests for cellulose thermal insulation

materials

2. TEST APPARATUS AND METHODS

2.1 Attic Floor Radiant Panel

Briefly, the basic elements of the test apparatus are a horizontallymounted 100 cm long specimen tray which receives radiant energy from an airgas fueled radiant panel mounted above the specimen and inclined at an angle

of 30° (see figure 1) . A pilot burner is used to initiate the test by open

flame ignition of the specimen. The gas panel generates a flux profile along

the length of the specimen ranging from a maximum of 1.1 W/cm2 to 0.1 W/cm2 minimum [4], The standard flux profile is shown in figure 2.

After the test chamber has been preheated to equilibrium conditions, the

specimen is placed into test position and the chamber is closed. Following

a two-minute preheat, the ignition flame is applied to the end of the specimen

located under the radiant panel. The test is continued until the specimen

flaming goes out (extinguishment) . The distance burned to the point of

extinguishment is converted to W/cm2 from the calibrated flux profile graph

and the result is reported as a critical radiant flux, W/cm2 [4]

For a material to pass the test, the critical radiant flux must be equal to or greater than 0.12 W/cm2 [3].

2.2 Smoldering Combustion

The specimen holder is an open-top 20 cm square stainless steel box which

is 10 cm high. During the test the specimen holder rests upon a glass fiberboard pad which is approximately 2.5 cm thick (see figure 5). The ignition

source is a cigarette without a filter tip which is 85 mm long.

2

' Repeatability precision - repeatability or within-laboratory precision is

defined in terms of the variability between test results obtained in the same laboratory on the same material [6]

^Reproducibility precision - reproducibility or between-laboratory precision

is defined in terms of the variability between test results obtained in

different laboratories on the same material [6]

3
The weight of material necessary to fill the holder at a settled density

is determined. The specimen holder is filled to the top with the required

amount of material. An 8 mm diameter vertical hole is made in the center of

the material, and a well-lit cigarette is inserted in the formed cavity. The

lit end of the cigarette is upward and flush with the sample surface. The

cigarette and specimen are allowed to burn for at least two hours or until

smoldering is no longer progressing. After the specimen holder has cooled

down to 25° C, the holder with its material residue is weighed and the weight

loss is determined. For a material to pass, there must be no evidence of

flaming combustion and the weight loss must be <_ 15 percent of the initial

weight [3]

3. LABORATORY QUALIFICATION

Prior to initiating the round robin test program, Mr. David E. Swanson

of the National Bureau of Standards visited a number of laboratories to check

the operation of their radiant panel apparatus. Special attention was given

to checking the calibration of the radiant flux meters and flux profiles.

The following is a discussion of the survey findings.

The calibration of the radiant flux meters, used for adjusting the

radiant flux profile for the test, was compared to that of an NBS calibrated

flux meter. Out of eleven laboratories checked, one was found to be using an incorrect flux meter calibration value. A correct calibration constant was provided for use by the laboratory. The laboratory survey indicated a general

pattern of initial difficulties in adjusting the radiant panels for the

specified radiant flux profile. In some of these laboratories, this may be

attributed to the lack of experience with the apparatus because the units

had been recently acquired, rather than an insufficient description of the

test procedure. In order to correct this problem, adjustments were required

on sample to panel distance, radiant panel angle, and gas and airflow rates.

Gas and airflow rates were difficult to adjust on several test instruments.

This was mainly due to the coarseness of the flow control valves. One panel

was being operated without airflow control to the burner, relying only on the

adjustment of gas flow for control. Another laboratory did not have the

optical pyrometer used for standardizing the thermal output of the radiant

panel. Several laboratories had experienced trouble with the temperatureactivated safety gas cut-off system on the panels. The thermocouples con- trolling the automatic shutdown were not located in the proper position.

Sporadic cooling of these thermocouples resulted in the gas flow to the

panels being cut off. These thermocouples were repositioned. The only other

significant problem noted was associated with airflow through the test chamber.

4
In one laboratory, the building exhaust duct was connected directly to the

test chamber stack by a flexible hose. This induced an unusually large

airflow through the test chamber which substantially lowered the chamber

temperature and also affected the radiant flux profile. The flexible hose was removed allowing natural convection to remove the products of combustion,

and the unit was recalibrated.

After the laboratory investigations were completed, the nine participants

were selected for the test program. Of these, two had assembled the apparatus

from drawings in the specification, and seven had commercially manufactured

test apparatus. Of the commercial instruments, two manufacturers were represented. Figures 3 and 4 show representative examples of commercial and

home-built test instruments that were used in this test program.

4. PARTICIPANTS

The laboratories who collaborated in this study are listed in appendix A.

The degree of experience among laboratories in using the insulation test

methods varied from one month to one year. Five of the participating laboratories provide commercial test services for the public while the others are government laboratories. In order to remain consistent with the usual practice in interlaboratory studies, the laboratories are identified in this report

only by code letters. It should be noted that one laboratory conducted only

the Smoldering Combustion test.

5. MATERIALS AND SAMPLE PREPARATION

Seven cellulose thermal insulation materials were obtained from

manufacturers for the test program. The basic ingredient in six of the

materials was ground waste paper while the seventh was cotton. The manufacturers indicated that all of the materials were treated with fire-retardant

chemicals. The fire-retardant chemicals in one material were added through a wet process while the chemicals for the six other materials were added by

mechanical dry blending. All of the materials were produced primarily for

the home insulation market. The materials are typically installed by being

blown into building spaces, attic floors and wall cavities by blowing machines.

The materials were received in bags containing insulation whose nominal weights

ranged from 9.1 to 18.2 kg (20 to 40 lbs). Before the insulation was separated into sample batches and blended, each product was given a code letter,

A through G, which was used throughout the program for identification.

5
After the bags were weighed, each material used in the test program was removed from its original bag and mixed separately. Mixing was accomplished

by blowing the insulation through 30.3 m (100 ft) of hose into a 1.8 m

3

(65 ft 3

) blending chamber using a commercial blowing machine. Depending on

the properties of the materials, two or three bags were fed through the blowing machine and into the mixing chamber before samples were taken from the

lot. Samples weighing a nominal 4.5 kg (10 lbs) were bagged separately and

code labeled for shipment to the participating laboratories. Before the bags were sealed, a 454 g (1 lb) sample was taken from each. These samples were

placed into a separate bag for each product and kept as a composite to be

tested by NBS . After each lot was mixed, the mixing system was thoroughly

cleaned before the next material was blended. When all the materials were

bagged, they were placed into groups for shipment and lot numbers were recorded

along with the laboratory identification number. The samples were then boxed

with a set of four hardboard specimens and a four-pronged pick, which was used

for fluffing the insulation, and shipped to the participants. For simplicity

and consistency, slight modifications were made in a few procedures and uniform

instructions were sent to the participants (see section 6)

6. EXPERIMENTAL DESIGN

Each laboratory participating in the test program received seven cellulose insulation materials and one set of four hardboard specimens. The

fire test procedures used by the participants in this interlaboratory test

program were slight modifications of tests found in Federal Specification

HH-I-515D [3]. The tests conducted were for Critical Radiant Flux (section

4.8.7 of HH-I-515D) and Smoldering Combustion (section 4.8.8 of HH-I-515D)

Both tests were performed on each of the cellulosic insulation specimens. The

hardboard specimens served as a reference material for Critical Radiant Flux

method only.

In order to maintain consistency in the test evaluation, minor changes

were made in the test procedures. It was requested that all laboratories

test their specimens at a fixed density instead of the settled density called

for in the specification. Tests on all insulation materials except C were

conducted at a nominal 48 Kg/m 3 (3.0 lbs/ft 3

) density with an allowable range

between 46.5 and 49.7 Kg/m 3 (2.9 and 3.1 lbs/ft 3

) . Because the blown density

of material C was much less than the others, it was requested that tests be

performed at a nominal density of 24 Kg/m 3 (1.5 lbs/ft 3

) with a range from

22.4 to 25.6 Kg/m 3 (1.4 to 1.6 lbs/ft 3 ).

6
Specimen preparation also varied somewhat from the procedure called for

in the specification. It was found that repeated passes of cellulose insulation through a blowing machine results in damage to the cellulose fiber and

alteration of its properties. Since the materials had already been blown

through a commercial insulation blowing machine when they were blended at

NBS , it was requested that the test specimens be prepared by hand, filling

the test containers to the weight required for the specified densities.

Care was to be taken to break up any lumps and to fluff the material using

the pick until the specimens evenly filled the test container.

The conditioning procedure for the Smoldering Combustion test was also

altered to conform with the procedure required for the Critical Radiant Flux

test. All materials and cigarettes were to be conditioned for a minimum of

48 hours in an environment of 21 + 3° C (69.8 + 5.4° F) and 50% R.H. before

testing.

7. TEST RESULTS AND DISCUSSION

Nine laboratories conducted tests and provided data on the Critical

Radiant Flux test. Ten laboratories conducted Smoldering Combustion tests

and supplied data. The data were compiled and compared with the requirements

set forth in the Federal Specification HH-I-515D. The specification states

in paragraph 3.1.9 that for a material to pass, the critical radiant flux

shall be equal to or greater than 0.12 W/cm2

. For smoldering combustion,

paragraph 3.1.10 states that a material must show no evidence of flaming

combustion and must have a weight loss <_ 15 percent of the initial weight in

order to be accepted.

7.1 Critical Radiant Flux Test

Three tests were conducted by each laboratory on each cellulose

insulation material; four hardboard specimens were also tested. Since loose

fill cellulose insulation and its properties are known to be variable, the use of a fairly uniform hardboard sheet, which has been used in other testing

programs, was included to provide a reference measure of test repeatability

and reproducibility. Table 1 lists the test results for critical radiant

flux provided by each laboratory.

Material D experienced five individual tests in two laboratories where

the specimen did not ignite; eight laboratories reported data for materials B

and F in which some or all of the specimens burned the entire length. The

results contained in these ten data cells were not included in the statistical

7
treatment. Two hardboard tests from laboratory number 2 were excluded from

analysis also because the laboratory indicated that the radiant panel

extinguished while the tests were in progress.

Table 2 shows the Critical Radiant Flux test results ordered from pass to

fail tabulation. Material B failed in seven of the the nine laboratories and

exhibited relatively low critical radiant flux values in the laboratories

where it passed (see table 1) . Materials E and F experienced failures in one

and two laboratories, respectively. In summary, the results of four materials

had full agreement in all nine laboratories. The results of one material

agreed in eight of nine laboratories, and the results of two materials agreed

in seven of nine laboratories.

Table 3 exhibits the results of a statistical evaluation which provides

information related to the precision of the Critical Radiant Flux test. The

test results were evaluated using statistical methods found in the "Tentative

Recommended Practice for Conducting an Interlaboratory Test Program to Determine the Precision of Test Methods" being prepared by ASTM Committee E 11 [6].

A brief presentation of the statistical methods used in this report is given

in appendix B. The table presents the overall laboratory average for critical

radiant flux, pooled repeatability standard deviation, reproducibility standard

deviation and the coefficients of variation for repeatability and reproducibility. (See appendix C for cell averages and standard deviations.) Although

material B exhibited the best repeatability with a coefficient of variation of

7.7 percent, it should be noted that this value was calculated using the

critical radiant flux results reported from only two laboratories. Material E

exhibited the greatest coefficient of variation for repeatability with a value

of 14.8 percent. The coefficient of variation for reproducibility ranged from

13 to 30 percent. The overall average coefficient of variation for repeatability for seven cellulose insulation materials was 12 percent; the average

coefficient of variation for reproducibility between laboratories for seven materials was 21 percent. These values were fairly close to the values for

the hardboard sheet material and also compare favorably with values for carpeting materials tested by the Floor Radiant Panel [4] and E 84 Flame Spread

tests [7] (see table 4) . As shown, the range and median coefficients of

variation of the Attic Floor Radiant Panel are reasonable when compared to

similar estimates available for other test methods. Furthermore, it was expected

that the precision estimates for loose fill cellulose would be somewhat higher

than that for carpeting. Thus, the testing of loose fill cellulose insulation

materials by this test method does not introduce exceptionally high levels of

variability. Also, a comparison of hardboard test results from this interlaboratory program shows better reproducibility than that obtained from an

8
uncontrolled program involving 21 laboratories using the Floor Radiant Panel

test. An informal "calibration" experiment was carried out before an attempt

was made to standardize various test parameters. This work was done in order

to determine the extent of between-laboratory variability. (The results of

the calibration experiment resulted in a tightening of the test procedure.)

The data show that the average critical radiant flux obtained for hardboard in

the present program was 0.20 W/cm2 and the earlier calibration experiment was

0.19 W/cm2

. The repeatability coefficient of variation for hardboard in this

project was 12.7 with a reproducibility coefficient of variation of 19.5 (see

table 3). The repeatability coefficient of variation for the hardboard in the

uncontrolled calibration experiment was 13.1 with a reproducibility coefficient

of variation of 91.5.

7.2 Smoldering Combustion Test

4 Ten laboratories supplied Smoldering Combustion test data. Each cell

consisted of three determinations as required by Federal Specification

HH-I-515D. Table 6 shows a tabulation of percent weight loss of the test

specimens as reported by the laboratories. Because of the split test results,

some pass and some fail, noted in a number of data cells exhibited in table 5,

calculations of repeatability and reproducibility were made for only three

materials

Figures 5 and 6 show examples of materials prepared for testing and the

specimens two hours after the cigarettes were ignited. It is evident that

where smoldering combustion was initiated and propagated readily a significant

weight loss occurred; where it was not initiated the weight loss was very

small. The chemical composition of the sample and the extent of separation

of the fire-retardant chemicals are principal determining factors in the

propagation of smoldering combustion.

Three laboratories experienced split test results within a single set of

tests. This can be seen in table 5 and is noted in table 6 by the asterisks.

There were six cells with split results out of a total of 70 cells. Four

materials experienced this phenomenon, C, E, F and G; materials E and F show

split results in two different laboratories. Material E exhibited the greatest inconsistency, passing in three laboratories and failing in seven. Within

the seven failing laboratories two data cells show passing results. This

variation appears to be directly related to the physical separation of fireretardant chemicals from the ground paper. A deposit of granular chemicals

Cell - each of p laboratories makes measurements on each of q materials.

This gives rise to p x q "cells". Each cell consists of n measurements [6].

9
was observed in the bottom of sample bags containing material E. Materials

F and G failed in nine of the ten laboratories with F exhibiting split results

in two data cells and G with split results in one. Materials B and D were

failures in all laboratories. Material C exhibited two failures in one data

cell and passed in the remaining nine. For statistical data on materials

without split results, see table 7.

Further analysis of table 6 provides some information associated with

reproducibility. Agreement among the laboratories was relatively good. The

results of three materials had full agreement in all ten laboratories. The

results of three materials agreed in nine of ten laboratories and the results

of one material had agreement in seven of the ten laboratories. It appears

that some variation in laboratory operations contributed to the scatter of

data

8. SUMMARY AND CONCLUSIONS

An interlaboratory program was carried out to determine the repeatability

and reproducibility of the Critical Radiant Flux and Smoldering Combustion

tests referenced in Federal Specification HH-I-515D. Seven cellulose thermal

insulation products were evaluated in ten laboratories. The results indicate

that the estimated precision levels of repeatability and reproducibility for

the Attic Floor Radiant Panel test were not significantly greater for loose

fill cellulose materials than for other materials, and compare favorably with

precision estimates available from other standard fire test methods. Physical

separation of chemical fire-retardants was quite noticeable in one of the seven materials and the likely cause of variability noted in the test results,

particularly for the Smoldering Combustion test. Based on the work of this

study, there is reasonable assurance that results from different laboratories

evaluating the same material for compliance with Federal Specification

HH-I-515D will be consistent.

9 . RECOMMENDATIONS

In view of the variation experienced with the Smoldering Combustion test,

it would be appropriate to further study the possibilities of improving the

test procedure.

10
10. ACKNOWLEDGMENTS

Appreciation is extended to the manufacturers who freely provided

materials for this test program and the participating laboratories who

conducted the testing without compensation. Mr. Bernard Schwartz of the

Consumer Product Safety Commission and the field offices assisted in obtaining the test materials. Statistical consultation was provided by Mrs.

Mary G. Natrella, Statistical Engineering Division, National Bureau of

Standards. Appreciation is also extended to Mr. Sanford Davis, Furnishings

Flammability Research, National Bureau of Standards, who provided assistance

through the test program, and to Mr. David E. Swanson for conducting the

laboratory survey.

11. REFERENCES

[1] Standard Test Method for Surface Burning Characteristics of Building

Materials, ASTM E 84-77, American Society for Testing and Materials,

Philadelphia, Pa. (1977)

[2] Gross, D. , A preliminary study of the fire safety of thermal insulation

for use in attic or enclosed spaces in residential housing, Nat. Bur.

Stand. (U.S.), NBSIR 78-1497 (1978).

[3] Insulation Thermal (Loose Fill for Pneumatic or Poured Application):

Cellulosic or Wood Fiber, Federal Specification HH-I-515D (June 15, 1978).

[4] Benjamin, I. A. and Adams, C. H., Proposed criteria for use of the

critical radiant flux test method, Nat. Bur. Stand. (U.S.), NBSIR 75-950

' (Dec. 1975) . [5] Standard Method of Test for Critical Radiant Flux for Floor Covering

Systems Using a Radiant Heat Energy Source, NFPA 253, National Fire

Protection Association, Boston, Mass. (1978).

[6] Tentative Recommended Practice for Conducting an Inter laboratory Test

Program to Determine the Precision of Test Methods, ASTM Committee E 11,

American Society for Testing and Materials, Philadelphia, Pa. (1978).

[7] Lee, T. G. and Huggett, Clayton, Interlaboratory Evaluation of ASTM

E 84-70, Tunnel Test Applied to Floor Coverings, Journal of Testing and

Evaluation, Vol. 3, No. 1, American Society for Testing and Materials,

Philadelphia, Pa. (1975) .

11
Figure 1. Attic floor radiant panel tester schematic - side evaluation

12
o

E

u

Uio

</>

z UJ0/S1IVM

13

Figure

2.

Standard

radiant

heat

energy

flux

profile
V

14

Figure

3.

Commercially

built

attic

floor

radiant

panel
15

Figure

4.

Home

built

attic

floor

radiant

panel
16

Figure

5.

Smoldering

combustion

test

(materials

before

testing)
17

Figure

6.

Smoldering

combustion

test

(materials

after

testing)
Table 1. Critical radiant flux data

Lab Material

A B C D E F G Hardboard

1 0.19 < 0 . n

a

0 . 16 0.51 0.10 0.14 0.15 0.21

0.20 <0.11 0.18 0.39 0.11 0.15 0.16 0.19

0.18 <0.11 0.20 0.41 0.12 0.13 0.15 0.23

0.19

2 0.24 < o . n

a

0 .20 0.49 0.18 0.21 0.26 c

0 .25 0.12 0.21 0.49 0.17 0.18 0.24 c 0.22 <0.11 0.19 0.53 0.19 0.16 0.25 0.22

0.21

3 0.29 0.14 0.25 0.46 0.21 0.16 0.38 0.17

0.24 0.15 0.27 0.41 0.20 0.18 0.35 0.15

0.34 0.17 0.28 0.46 0.21 0.15 0.41 0.14

0.13

4 0.18 < o . n

a 0.16 DNI b 0.18 < o . n

a 0.21 0.22

0.19 <0.11 0.14 DNI 0 . 14 0.11 0.19 0.22

0.22 <0.11 0.13 DNI 0.15 <0.11 0.19 0.22

0.23

5 0.23 < o . n

a 0.27 0.39 0.13 0.14 0.25 0.21

0.25 <0.11 0.28 0.45 0.15 0.13 0.22 0.22

0.24 < 0.11 0.30 0.41 0.15 0.12 0.19 0.15

0.12

6 0.21 0.11 a 0.26 0.55 0.17 0.13 0.24 0.21

0.12 0.11 0.21 DNIb

0 . 15 0.16 0.20 0.22

0.16 <0.11 0.24 DNI 0.12 0.14 0.24 0.20

0.25

7 0.20 0.13 0.32 0.62 0.17 0.12 0.27 0.23

0.23 0.13 0.31 0.49 0.21 0.19 0.37 0.23

0.20 0.13 0.31 0.44 0.22 0.13 0.26 0.23

0.21

8 0.27 < 0 . 12 a 0.22 0.55 0.27 0.14 0.21 0.22

0.27 < 0.12 0.28 0.54 0.18 <0. 12 a 0.22 0.25

0.27 < 0 . 12 0.25 0.53 0.18 <0.12 0.21 0.27

0.28

9 0.18 0.10 0.18 0.60 0.20 0.16 0.18 0.20

0.20 0.10 0.20 0.43 0.16 0.17 0.22 0.17

0.17 0.10 0.24 0.40 0.16 0.14 0.18 0.20

0.12

In the statistical treatment of the data, data cells containing

values designated by the less than sign "<" were not included in

the analysis.

bDNI = did not ignite. These data cells were not included in the

statistical treatment.

c Two tests were not included because the radiant panel went out

while the tests were in progress.

18
Table 2 Pass and fail tabulation (critical radiant flux)

by materials and laboratories

Lab

C

P

P

P

P

P

P

P

P

P

A

P

P

P

P

P

P

P

P

P

F

P

P

P

F

P

P

P

F

P

B

F

F

P

F

F

F

P

F

F

No. of

Failures 0 0 0 0 12 7

19
Table

3.

Precision

estimates

of

critical

radiant

flux

measurements

4-1o uo

4-> 4-1 c

44 (13 0

44 -H J4

<u >4 o. O (0 QJ U > Pi

(D C-H lo ro LO CO LT) LO H O 0 • U-H p ro vo ro rH CT\ (T\ o h 4J mi l—i pH <N (N CM CM rH rH <N

4->

C

•H

O i—I "H

4J X! (0 H *H u > 3 ai ms Q o

>4 • ams o -p

Pi ca

CT> LO o r- r- rH 00 o

rH CM in VO o O o o o o o o o o o o o o o o

44o

astm

rc)4

d)><

ient

of

on

for

bility

r- 00 00 CG r~ 00 o O -H <d •H 4-> 4-> ro rH 00 rH ro

44 f0 rd

4-. *H <U o i4 a o ro 0) U > Pi

rH rH iH rH i—l

r-» fM c

>1 o

4-1 -r4 •H 4-1(C *H H

X! >

res <u

4->

Q

rtl 0) • ams

O) 4-1 « cn

rH rH VO o 00 CM VO

rH C4 (N CM CM CM VO CM O O O o O o o o O O O o o o o o

440

asCn

fdP • a>>^ i

CM CM o o i—1 r- VO

in r- CM ro ro

O

rH rH rH CM CM CM CM • • • • • • • • o o o O o o o O

S4

ai

4-4

Its S

CQ Cm

W

ua

ms

S4

nso

xi

ms

>4

n3 PC 2 0

nsulation

Materials

11.7

Insulation

Materia
Table

4.

Comparison

of

precision

estimates

for

fire

test

methods

G c O (0 •H •H

H

O r~

4J »p IN rH IN

•d©

>1-H S

4J P

•r4 <0 rH >

•H

.0 44 •H O O3 4J •O C 0 0) V4 *H

O VO

m

04

O co

H n-

<U -H

04 4-i a)

O 0 O

44 O' P p •P

<u

G o <d r-~ u a rH G c O id •H •H IN rH 00

•P -o rH r4 n d) >i-h

-P

p

•H (0 H >

•H

.Q 44 s

id 0

-P

<0 -P

(1)

C

Oi d) <D -H « o in ffi r-~ •H i-4 f-4 IN

44 d) 44 o 0 o 0

0)

G

pp 4J 0 id u os 03 00

r4 (])

H r-t

m

id •H

O 4-> 4J •H tf rH 0) d) P 3 Of a

<u d) f-4

p P

4J 0) i-4 id id

id 0 d)

u

U S o u

*0

4J

(0

d> 4J P M G 0 id 4-i O f-4 •H W 00

*o rH d) T3 dJ

4->

O hi

C id E-<

w

m xl id 04

dJ 4J

O Of iH s

64 (U •H P d) S 4J 4-1 0 c to

4J

G o <d «e < id rH df •H hi •o

id 04

21
Table 5. Percent weight loss - smoldering combustion test

Lab Material

A B C D E F G

1 0.8 66.8 0.7 57.5 54.5 47.5 54.9

0.3 66.4 0.1 52.9 52.4 43.2 55.2

0.2 67.3 0.2 49.1 49.7 46.3 54.4

2 0.5 62.5 -0.1 70.8 0.2 0.0 0.2

0.4 62.4 -0.2 50.8 0.2 0.1 1.3

0.6 64.5 -0.1 46.6 0.1 0.2 0.1

3 2.4 61.3 1.5 54.2 -0.2 49.3 51.7

3.4 60.7 1.3 54.0 -0.5 46.8 51.8

2.9 60.3 1.3 55.7 0.2 48.7 51.3

4 1.0 60.0 25.3 77.4 46.5 2.5 57.4

1.0 62.1 0.9 62.6 40.0 40.0 55.4

1.0 60.0 40.7 68.9 45.0 35.0 50.0

5 0.3 67.9 0.3 78.6 0.3 62.2 1.5

0.2 69.9 0.3 81.2 0.3 80.4 71.7

0.2 68.3 0.1 79.6 61.3 79.6 0.9

6 9 . 4

a 53.3 0.07 74.1 50.0 32.7 60.0

0.9 57.0 -1.1 51.1 47.8 35.3 58.9

0.5 61.5 0.1 56.6 42.5 29.7 53.2

7 0.5 52.9 0.7 40.4 40.2 34.0 38.0

0.7 55.1 0.8 44.9 43.7 37.0 48.6

0.2 61.2 1.5 48.7 41.1 35.0 47.3

8 0.6 73.1 0.1 77.3 50.7 74.4 57.7

0.7 70.8 0.0 84.0 50.4 75.3 64.3

0.5 73.3 0 . 0 73.8 48.6 69.6 51.5

9 0.6 62.3 1.4 81.1 50.5 0.6 62.0

0.5 63.5 1.3 77.0 57.2 0.5 50.5

0.3 70.3 1.4 73.4 0.5 70.8 53.2

10 0.0 61.9 0.0 48.9 - 1.0 51.1 31.5

0.0 63.7 0.4 62.4 0.0 34.1 54.2

0.4 60.4 -1.2 73.7 0.1 35.7 56.6

aThis value was considered to be outlier and was not used in the statistical

evaluation.

22
Table 6. Pass and fail tabulation (smoldering combustion)

by materials and laboratories

Lab

1

2

3

4

5

6

7

8

9

10

No . of

ailures

P

P

P

F*

P

P

P

P

P

P

F

P

P

F

F*

F

F

F

F*

P

F

P

F

F*

F

F

F

F

F*

F

F

P

F

F

F*

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

10

*Of 3 tests, 1 or 2 are close to zero, and the other much above 15%,

D

F

F

F

F

F

F

F

F

F

F

10

23
cop

-P

cn3

X!EOo

CncPp

<d "O«—

oE

cn

cn

cnO cn i—! X t

of

for

ility

GGX CN

CD 0 -P • •P -P O <N 0X3 rH •p id d X -P 0 X p p

cu id

a 0 > CD u on i—

>1 X c

•P

O

r—I -H

•H 4-> xi id •H *P O > 3 <D a op • and

<d

x & cn

ro

00 r- • • • o in ro

x 3 x cn Cn (D •H p

a)

3:

X

cn

4-) CD G x

a)o x p -p

a)

x

a o,

cn

4-1o x3

cn o

a)x

xx

id -p E &

•PX 0) (0 rP

CD Id •p c P O CD •P X

cn id p E o

CD P P O

IX

X

rCD I—

X

ft! Ei

44O P >• 0 -P X UH -H c rH

CD

C -P *3* o <N

•H

OX • • • o p id CM CN

•p

XX ro rH

X id id X •P CD

CD

pa 0 id CD U > on

Sp c X 0

*p •H X X •p id X •p

id > X CD

id

D

CDa • CD TD

onX

cn

cn in i

O 04 i

CDCn

rp Id rP P

rd ai p >

<u < >O XmX o

prn

40

40n

40

rd •PP

CD X

<d 2 < CQ

Q

24
APPENDIX A

PARTICIPANTS IN THE INTERLABORATORY FIRE TEST PROGRAM

Certified Testing Laboratories, Inc.

Dalton, Georgia 30720

Commercial Testing Company, Inc.

Dalton, Georgia 30720

Consumer Product Safety Commission

Engineering Laboratory

Bethesda, Maryland 20720

General Services Administration, FSS FML

Washington, D.C. 20405

Hauser Laboratories

Boulder, Colorado 80306

Independent Textile Testing Service, Inc.

Dalton, Georgia 30720

National Bureau of Standards

Center for Fire Research

Washington, D.C. 20234

Oak Ridge National Laboratory

Operated by Union Carbide Corporation

Oak Ridge, Tennessee 37830

Ontario Research Foundation

Sheridan Park, Mississauga, Ontario

Canada L5K 1B3

Southwest Research Institute

San Antonio, Texas 78284

(Results received 8-28-78, too late for inclusion in the analysis.)

Underwriters' Laboratories, Inc.

Northbrook, Illinois 60062

(Results received 12-27-78, too late for inclusion in the analysis.)

United States Testing Company, Inc.

Hoboken, New Jersey 07030

A-l
,

.s3'

c- 4

'
APPENDIX B

STATISTICAL METHODS

(cv

r

)

(CV

d. . ID n

P

s ij

ISL>j

(s r>j

(s R>j

(Sj

X j

X . . 1 ]

X . J

Nomenclature

Coefficient of variation for repeatability (within-laboratory)

Coefficient of variation for reproducibility (betweenlaboratories)

Cell deviations from average

Number of replicates per cell

Total number of laboratories

Cell standard deviation

Component of variance between laboratories

Pooled standard deviation for repeatability

Standard deviation for reproducibility

Intermediate variance quantity

Average for cell (i,j) where i represents the laboratory

and j the material

Average for one material for all laboratories

B-l
Pooled Standard Deviation for Repeatability:

(s )

. r 3

( 1 )

Equation (1) is applicable only when the number of replicates is the same for

each laboratory for a given material. Where there are missing replicates

in one or more laboratories use equation (la)

(s V

E. (n. .-l)s? . 1 hi

X, (n,,-l)

(la)

i i]

Coefficient of Variation for Repeatability:

(CV ) = 100 (s r

} j

Standard Deviation for Reproducibility:

First Calculate the "deviations from average" for each cell (i,j)

( 2 )

Then calculate the intermediate variance quantity where:

( s _)x

z . (d. .

)

i i j

P-1

(3)

(4)

Using (s_) and (s r

)

calculate the

x j r 3 where

"component of variance" between laboratories,

(s

j (5)

The variance of the total variability of a test results including both within

and between laboratory variability is given by:

< S R>j

= >j

+ < S

L»

2

j

( 6 )

B-2
Coefficient of Variation for Reproducibility:

(CVR)j = 100

(S R* j

X

j

(7)

B-3

APPENDIX C

CELL AVERAGES AND STANDARD DEVIATIONS FOR

CRITICAL RADIANT FLUX AND SMOLDERING COMBUSTION

C-l
Critical

Radiant

Flux

'Opnop

(Q

ffi

m in CO CN in o in in CN o rH CN t" CN CN in 1"-

O

CM CN rH CN rH CN CN CN rH CN o o o O o O o o o O<n

p

in

<v A

Cn •H

SCOP QOU

r" CO CO o r- l" r- o ID

CO o o •H rH rH "d* r* r>* in rH <n in in <3* o o o ; o o o o O o A A

CO o o o t"

O CO CO rin in CO cn CN CN o rH cn CO

rH CN CO rH CN CN CO CN rH CN o o o o O o o o o O o o CO CO CO o C' rH

CO o ID

v 00 CO rH in o co

rH CN CN rH CN CN CO CN CN CN • • • • • • • • • • o o o o o o o o o O

<n

<n o o o CO o o CO o

OO co cn cn ID rH 00 CN

rH CN CN rH CN rH CN CN rH CN • • e . • • • • • • o o o O o O o o o o m

<3 •HP

0) -P

fO s w

fcl

CQ8

P5 o o t"- CO CO o o CO cn

rH CO o in -31 o rH CD

rH rH CN rH rH rH CN CN rH rH o o O o o o o o o o o CO co o o CO r~ r- r-~ CN

00 ID rH co

N1 CN in in

rH 1—rH rH rH rH rH rH rH rH . . . • . • • . . • o o o o O o O O o O V V o co co o o o O o o CN rH rH in rH rH rH co CN rH N’ rH iH rH rH rH rH i—1 rH rH rH • • « • . • • . . • o O o O O o o O o O V V V V V V V

co <D CO cn

<utn

nJp

0)

<n

CM

OU

C-2

*Only 2

values

were

used

to

calculate

the

average.

Two

tests

were

discarded

because

the

radiant

panel

went

out.
TlU * 0 0> r-~ r* in 00 CM o VO 00 VO 0 i—

o •H o CM rH CM CO CM

XI

O o O o o O o o o o

T3 • • • • • • • • • • Vh o o o o o o o o o o 0

ffi P

to

to 0 <3* co Cv rH CO o 00 CM G ,G VO CM CM n o\ rH o VO 0 Q O O O 1 O 1 o o rH o

•H •H • • • • • • . • P X o o o o o o o o 0H 0 X P 3 VO o o CM o CO 1—

VO CO CO 0 i—

o rH co rH co CM VO o CM CM Q P fa O o o o O o O o o o o

to • • • • • • • • . • 03 0 P o o o o o o o o o o U 5 G 0 0 0

03 1-3 *H o o in in in in VO o o o G *0 CM i—

rH rH rH CM o CO CO CM 0 & 0 U O o O O O o o o o o P 0 fa • • • • • • • • . • co nP rH o o o O o o o o o o 1—1 0

rH 03

O o in o rH o in S'*- o in VO

(1) 0 -H rH i—

in CM rH 1—1 o rH CM

CJ

M P < o o o O

O o o o o o 0 -H • • • • • • • • . • 03 t >H O o o O o o o o o o 0 H CJ P o

<0

O o VO rH CM in VO CM CO •^r e (0 i—1 rH o CM rH CM CM in CM CM •H 1—1 w o o o O o o o o o o P 0 . o • . . • • • • •

C/1 •H o o o o o o o o o o W U0P o in in o in 00 in rH 0 (

1 CM i—

rH rH CO rH CM s fa o o o 1 O O o 1 o o . • • . • • • • o o o o o o o o

in o rH

CQ *—

o pH 1 1 o 1 1 1 o 1 1 o • • • o o o

toG P 03 0

<3 1—1 tN CO 3* in VO 00 <T>

U -H

TO 0 P 0 03 0

rH

C -H 0 0 > O P 0

fa

W

Q

C-3

Only 2

values

were

used

to

calculate

the

standard

deviation.

Two

tests

were

discarded

because

the

radiant

panel

went

out.
Cell

Averages

Percent

Weight

Loss

Smoldering

Combustion

Test

co co O o e'- r- r- 00

i—j o iO CO lO lO en i—i lO in

• • • • • • • • • • 0 CO O' <71 <n o O' 00 r* rH co m in in lO > lO O f'- <0 10

co <o r* o o f' o o o 10

CO r- r* r-' CM •O' O' CO o CO

• • • • • • • • # • • lO CO o o 00 lO (N in CM CO

lO 10 VO 10 lO in in p- 10 10 lO

rc) CO o o O co o r~ o t" CO CM V in O CM C" O' lO O' *H r-

• • • • • • • • • • • o o CM rH o o o o o O o

>1u

o

+j

nJn

o

,q

fC

cm co in cd i" oo

C-4

The

9.4

in

the

original

data

is

treated

as

an

outlier.

The

average

is

of

2

cell

values

only.
Cell

Standard

Deviations

Smoldering

Combustion

Test

rH CO m ro rH «H in 00 in (N

CN c\ <J\ cn O r-H rH 00 r-

• • • • • • • • • • • CN o »H CN in co (N rrH rH rH

>1u

o

•Pu

o9

CM co in 10 oo <j\

C-5

Pooled

Standard

0.24

2.51
WBS-1 14A (REV. 9-761

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 79-1588

4. TITLE AND SUBTITLE

Interlaboratory Evaluation of the Attic Floor Radiant

Panel Test and Smoldering Combustion Test for Cellulose

Thermal Insulation

5. Publication Date February 1979

7. AUTHOR(S)

J. Randall Lawson

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, city, state, ZIP) Consumer Product Safety Commission

Textile and Mechanical Engineering Group

Bethesda, Maryland 20202

13. Type of Report & Period Covered

Final Report

15. SUPPLEMENTARY NOTES

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

16. ABSTRACT (A 200-word or leas tactual summary ol most significant information. If document includes a significant bibliography or

literature survey, mention it here.) An i nter laboratory test program was conducted to provide estimates of repeatability and reproducibility of fire tests for cellulose loose fill insulation. The test methods evaluated were for critical radiant flux, using the Attic

Floor Radiant Panel, and for smoldering combustion; they were based on Federal Specification HH-I-515D. Seven commercially manufactured cellulose thermal insulations marketed

for residential use were evaluated by each procedure. An additional set of four replicate hardboard specimens were tested by each participant using the Attic Floor Radiant

Panel. Nine laboratories conducted the Attic Floor Radiant Panel test, and ten con- ducted tests for smoldering combustion. The testing was conducted during the month of

June 1978. The participating laboratories were surveyed prior to testing in order to ensure conformance to the critical details of the test apparatus and procedures.

The between-laboratory coefficient of variation for critical radiant flux ranged

from 13 to 30 percent with an average for seven insulation materials of 21 percent.

Estimated precision levels of repeatability and reproducibility for the Attic Floor

Radiant Panel test when compared to other standard flame spread tests and materials are favorable. Data from the Smoldering Combustion test was evaluated on a pass/fail basis

with agreement by nine of ten laboratories for six of the seven materials tested. Sever

of ten laboratories also agreed on the seventh material.

Based on work of this study, there is reasonable assurance that results from different laboratories evaluating the same material for compliance with Federal Specification HH-T-515n will hp cnnsi c;1-pnt17* KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Attic floor radiant panel; cellulose thermal insulation; critical radiant flux; flame

spread; test methods; smoldering combustion.

18. AVAILABILITY 0 Unlimited

I | For Official Distribution. Do Not Release to NTIS 0Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

ET1 Order From National Technical Information Service (NTIS), Springfield, VA. 22161

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