NBSIR 74-495

Development of a Radiant Panel

Test for Flooring Materials

L. G. Hartzell, Research Associate

Armstrong Cork Co.

Lancaster, Pa.

Fire Programs

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

May 1974

Final Report

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 74-495

DEVELOPMENT OF A RADIANT PANEL

TEST FOR FLOORING MATERIALS

L. G. Hartzell, Research Associate

Armstrong Cork Co.

Lancaster, Pa.

Fire Programs

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

May 1974

Final Report

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

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

Contents

Page

1. INTRODUCTION 1

2. A REVIEW OF PREVIOUS EXPERIMENTAL RESULTS ON THE

TEST METHOD 4

3. STRATEGY FOR TEST DEVELOPMENT PROGRAM AT NBS . . 4

4. TEST EQUIPMENT 6

5. NBS TEST PROGRAM 7

5.1. Phase I - Comparison With Previous Test

Ratings 7

5.1.1. Comparison of Rating Performance

With Other Fire Test Methods ... 9

5.2. Phase II - An Exploration of Various Test

Heating Conditions and a Study of the Rating

Method 10

5.2.1. Test Operation at Several Thermal

Conditions 11

5.2.2. An Examination of Test Repeatability 14

5.3. Smoke Generation 15

5.4. Phase III - A Study of the Effects of

Variations in Test Procedures and Test

Conditions 15

5.4.1. Effect of Changes in Initial Chamber

Air Temperature 16

5.4.2. Effect of Changes in the Ignition

Procedure 17

5.4.3. A Study of Induced Air Flow Patterns 21

5.4.4. Effect of Specimen Conditioning and

Wear 22

5.4.5. Substrate Study 23

5.4.6. Summary of Phase III 24

5.5. Phase IV - Study of Thermal Conditions

During Burning 25

5. 5.1. Heat Flow. 25

6. REVIEW 2 8

6.1. Test Apparatus 29

6.2. Flame Spread Index 30

APPENDIX A. THE ARMSTRONG CORK COMPANY FLOORING

RADIANT PANEL DEVELOPMENT . 32

A.l. Test Parameter and Apparatus Design Criteria 32

A. 2. Armstrong Test Apparatus 33
A. 3. Armstrong Test Procedure 33

APPENDIX B. STATISTICAL ANALYSIS 36

B. l. Correlation of Test A with Test B 36

REFERENCES 37

TABLES

Table 1. Sample Identification 39

Table 2. Flame Spread Index and Chamber Temperature

Rise Results and Comparison Between AFRP-1 and

AFRP-2 40

Table 3. Flame Spread Ratings and Comparison .... 41

Table 4. Flame Spread Rating Results and Heat Flux at

Extinguishment For Several Thermal Conditions. . 42

Table 5. Repeatability Results 43

Table 6. Flame Spread Ratings and Comparison .... 44

Table 7. Test Schedule 45

Table 8. Flame Spread Results » . . 46

Table 9. Humidity and Wear Tests 47

Table 10. Effect of Substrate on Flame Spread Distance 48

ILLUSTRATIONS

1 Room Fire Situation 50

2 Original Apparatus 51

3 Original Apparatus Enclosed 52

4 Radiant Panel Apparatus 53

5 Schematic Diagram of Control Equipment 54

6 Phase I — AFRP-1 and AFRP-2 — Heat Flux at Sample

Surface 55

7 Comparison, AFRP-1 Vs. AFRP-2 (less than 100 only)

Least Squares Fit (Correlation Coefficient, r) . . 56
8 Phase I — Individual Test Comparison — AFRP-1 Vs.

AFRP-2 5 7

9 Phase I — Graphical Comparison — AFRP-2 Vs.

AFRP-1 and other tests 58

10 Phase II — Flux Distribution Curves 59

11 Phase II — Distribution of Burn Lengths 60

12 Phase II — Distribution of Burn Lengths 61

13 Phase II — Graphical Comparison — AFRP-2 Vs.

other tests 62

14 Phase III — Thermocouple Placement in Chamber

Walls 63

15 Phase III Part 1 — Preheat Series W-1 Flame

Spread Distance Vs. Time 64

16 Phase III Part 1 — Preheat Series A-5 Flame

Spread Distance Vs. Time 65

17 Phase III Part 2 — Displaced Ignition R-3 Flame

Spread Distance Vs. Time Ignited 31 cm, 12.5 min. . 66

18 Phase III Part 2 — Displaced Ignition N-2 Flame

Spread Distance Vs. Time Ignition 41 cm, 30.6 min. 67

19 Phase III Part 2 — Displaced Ignition A-5 Flame

Spread Distance Vs. Time Ignited 31 cm, 8.2 min. . 68

20 Phase III Part 3 — Study of Air Patterns Arrows

Indicate Flow Directions 69

21 Phase III Part 3 — Study of Air Patterns Air

Velocity Measurements 70

22 Phase III Part 3 — Study of Air Patterns Observation of TXl^ Pattern With Burning Sample 71

2 3 Phase IV -- Locations of Thermocouples and Heat

Flux Sensors 72

24 Phase IV — Heat Flux Meters — Test 187 ..... 73

25 Phase IV — Total Heat Flux Sensors — Test 193. . 74

DEVELOPMENT OF A RADIANT PANEL

TEST FOR FLOORING MATERIALS

L. G. Hartzell

ABSTRACT

This paper summarizes the work of a year long

program to continue the development of a radiant

panel type test for flooring materials, the original

concept of which was developed at the Armstrong

Cork Company's Research and Development Center in

Lancaster, Pennsylvania. This program at the

National Bureau of Standards had as its goal, the

further development of the test for possible adoption as a standard ASTM test method.

The program work was diyided into five phases.

During the first phase, an attempt was made to duplicate the performance of the original apparatus in

a similar one at the National Bureau of Standards

Laboratory. The proof of this duplication was shown

in replicate testing using a wide range of flooring

on both apparati.

In the second phase of the program, a new set

of test conditions were found in an attempt to

eliminate some of the more serious equipment and

procedural problems of the test. These new conditions provided the test with the ability to rate

flooring materials according to their ability to

resist the surface flame spread.

Under the third and fourth phases of the program, the effects of changes in some test parameters

were investigated and other test characteristics were

measured. Phase V, the data analysis and report,

concluded the program.

Key words: Carpet; fire test; f lammability ; flooring;

heat flux; ignition; radiant panel.

1. INTRODUCTION

During this century, the importance of public safety has

been recognized and with it have come tests designed to determine performance characteristics of various materials. The

measurement of the effects of fire on a material, and, more

1
particularly, the material's surface f lammability represents

a need that touches upon a critical aspect of life safety.

During the past 25 years, much effort has been given to

develop test methods for f lammability . The driving force

behind this development is usually need. In the past, experts

have felt that the surface flammability of walls and ceilings

has played a key part in propagation of fire within a structure.

However, the experts also have held that flooring has not been

considered a major hazard. Mr. J. A. Wilson, of the Factory

Mutual Engineering Division, in answering a letter of comment

to his paper on surface flammability methods [1]^, stated that

the lack of a test procedure for evaluation of floor coverings

was primarily the result of a relative lack of need for such

data. Furthermore, Mr. Wilson went on to state that, "Within

the Factory Mutual experience, which covers many years, there

has been no fire where the combustibility of the floor coverings

was a significant factor."

The above referenced symposium was published in 1961.

Undoubtedly, at that time there were reasons not to consider

floor coverings as a major hazard, given all other combustibles

usually located above the floor covering. However, recently

floor coverings and more particularly carpeting has found its

way into places where it had not usually been placed, such as

hospitals, nursing homes, and hotel corridors and lobbies.

Furthermore, reports of recent fire tragedies have proven that

the flooring can be a major contributor through spread of

flames, and smoke and heat evolution. When under the influence

of a high thermal load, flooring can act as a means of transferring fire and its products from its point of origin to

areas that would otherwise be inaccessible to the fire.

Logically, then, as Mr. Wilson has said, since the need

for evaluation has arisen, test procedures have been suggested.

Unfortunately, due to pressures of economics and time, standards

makers have in the past found it easier to specify flooring to

be tested under the existing surface flammability tests for

wall or ceiling material. The problem with this approach is

that until very recently there was not one accepted test method

which employed a sample mounted horizontally and face up. In

the two most commonly used surface flammability tests, the

Steiner Tunnel (ASTM E-84) and the radiant panel (ASTM E-162),

the sample is mounted either horizontally upside down or upside down at a 30° angle to the vertical, respectively.

Obviously this sample mounting procedure serves to create

testing problems for flooring. In addition, these tests do

Figures in brackets indicate the literature references at

the end of this paper.

2
not simulate any real life situation for floors and thus

should not be expected to properly examine differences in

types of flooring (resilient flooring, shag carpet, plush

carpet, etc.) and the differences in their reaction to fire.

With the acceptance of the methenamine tablet test, DOC-FF1-70, there is now a test with proper sample mounting.

However, the tablet test is only an ignition standard and is

still inadequate to determine relative surface flammability

for flooring materials under severe fire loading conditions.

This, then, was the background for the flooring radiant

panel originally developed by the Armstrong Cork Company [2]

which satisfies the need for a test of floor covering materials

and not only simulates realistic mounting conditions for flooring

but also the energy inputs expected in a real fire situation.

The original researchers of the project put fire situations

into two classes, the room class and the corridor class. In

the room class, the situation is that of an average size

office space about 10 ft x 20 ft x 10 ft high with a high

heat load in furniture, papers, periodicals and carpeting.

This class assumes relatively quiescent ambient conditions.

In the corridor class, there is variable draft available,

but little in the way of combustibles is present outside of

the corridor lining materials.

The room class was chosen since its condition could be

easily simulated by a radiant panel apparatus. In addition,

this choice eliminated the need for a complicated study of

draft air conditions. In the early stages of a room fire

following ignition, typically one object of relatively high

heat load such as a stuffed chair or sofa is burning. This

provides to the flooring an ignition source and a radiant input which is at its maximum near the ingition source, (See

figure 1) . The original radiant panel apparatus was designed

to simulate this situation. Materials were assigned a flame

spread index based on flame spread distance or on time to

spread the full length using red oak = 100 as a comparison

standard similar to the procedure in ASTM E-84. A description

in Appendix A is given from early correspondence of Z. Zabawsky,

the Project Director, to Subcommittee IV of ASTM Committee E-5,

which details the early thinking that went into the design of

the original apparatus to simulate this condition. The Appendix

also shows the design and procedure that resulted (refer to

figures 2 and 3 for sketches)

.

Although the original design of the apparatus was the

result of considerations of a room fire situation, nevertheless

in the present work, which is directed to the corridor situation, the test was still considered valid since it serves to

measure a basic property of flooring regardless of its end use.

3
2. A REVIEW OF PREVIOUS EXPERIMENTAL

RESULTS ON THE TEST METHOD

During the past two years, extensive testing was done by

Zabawsky on a wide range of flooring materials over a wide

range of substrates. Feedback from the results led Mr. Zabawsky

to a number of apparatus and procedure changes. For example,

the horizontal sample level inlet ports along the sides and ends

of the sample were opened. This provided sufficient combustion

air and eliminated strong drafts across the sample. Also, the

specimen rating length was increased from 24 to 32 inches and

with it also the red oak rating time. These improvements made

the test easier to perform and more repeatable.

In all, 271 tests were conducted by Zabawsky covering five

different resilient floorings, red oak, hardboard, and various

carpets using seven different types of fibers. The carpet was

tested over three different pads (underlayment cushion) and four

different substrates including 1/4 inch asbestos cement board,

1/2 inch phywood, 5/32 inch pressed hardboard, and 2 inch concrete. Of these tests, 197 were run in replicate, achieving

a 3.5% coefficient of variation level ^. Carpets tested over

asbestos-cement board and concrete generally achieved lower

flame spread indices than when tested over the hardboard or

plywood, presumably due to the relative heat sink and thermal

insulating values.

3. STRATEGY FOR TEST DEVELOPMENT PROGRAM AT NBS

The first task of the program at its new location was

the formulation of project goals. Toward this end, a three

part attack was formulated to study performance, relevance,

and feasibility.

Under performance, the goal is to achieve a high degree

of reproducibility. That is, not only must there be good

agreement in the results of duplicate samples tested on the

same apparatus, but the agreement must cover duplicate

samples tested in two different apparatus. In the present

study it was decided that a deviation of less than 10% from

the mean for 9 5% of the population of results for a given

specimen would indicate satisfactory reproducibility.

The accuracy and precision of a test notwithstanding,

the test is meaningless if nothing is gained by the knowledge

of its results. This comes under the term relevance.

Ideally, small scale tests correlate with the full scale

situation.

The percent coefficient of variation is the standard deviation

divided by the mean of a group of data expressed as a percent.

4
Feasibility is an important consideration in a test method.

Is the test economically suited to widespread use? Is the

apparatus small enough to be located in a typical laboratory?

Does the test take hours of preparation and testing for one

single result, or does the test consume an unreasonable amount

of material? These are questions to be answered in the consideration of feasibility. In the study of flooring f lammability

,

a full scale corridor would probably rate high in the areas of

performance and relevance. However, in answering the questions

above, one finds the corridor unfeasible as a laboratory size

test.

The next step was the decision of how best to attack the

above goals. After consideration of each goal, it was decided

to use this program to study test performance. The reasoning

behind this decision had to do with past and future studies.

To begin with, in a study of relevance, there needs to be

sufficient full scale data available for correlation purposes.

At the time this program was being planned, that data was not

available. However, since it was expected that the data would

be available in the future, preparation for attacking 1:his goal

could best be served by testing a wide range of flooring,

including many materials that would eventually undergo large

scale testing. Therefore, at least this much of the relevance

goal would be included in the program.

The feasibility goal had essentially been achieved. A

cost study done by one of the original developers showed that

the complete cost of construction of the Flooring Radiant Panel

was around $3, 000 in 1970. [3] This is a relatively inexpensive

f lammability test. In addition, the test takes a 5 in x 25 in

sample which is inexpensive to provide, and the average test

schedule would easily permit one operator to conduct six to ten

tests per day. Finally, the apparatus itself is about 5 ft

long by 2 ft wide by 7 ft high. Add an equal amount of space

for instrumentation and one can see that the entire setup is

small enough for most any laboratory. Furthermore, no unusual

services are needed, only a supply of gas fuel, and air, an

exhaust hood of at least 600 CFM capacity, and normal electrical service. The conclusion, then, was that the Flooring

Radiant Panel Test is a feasible test within the context stipulated.

This left the study of test performance yet to be done.

Toward this end, a one year program of five phases was developed. The phases were as follows:

Phase I Installation of and familiarization with equipment and comparison with previous results from

the original apparatus.

5
Phase II Determination

procedure

.

of optimum test conditions and

Phase III Study of effects of sample and test condition

parameter changes.

Phase IV Special studies of test characteristics for

research and large scale correlation purposes.

Phase V Data analysis and report.

Included as part of Phase II was testing of a wide range

of floor covering materials as mentioned above for the purpose

of future correlation with larger scale work. This range of

samples included seventeen carpets, a rubberized hair jute pad

backing, six resilient floor coverings, and red oak. The carpet

samples were obtained from Man Made Fibers Producers Association

(MMFPA) and were part of a series supplied by them to NBS for

use in flooring f lammability studies. Samples tested in this

series were also tested in standard surface flammability tests

such as the Steiner tunnel (ASTM E-84) and the radiant panel

(ASTM E-162) as well as in experimental facilities such as the

NBS corridor, UL-992 chamber and the Man Made Fibers Producers

Association Model Corridor [4] . In addition, a selection of

this series has already undergone testing in an earlier version

of the Armstrong Flooring Radiant Panel. The resilient flooring

was supplied by the Armstrong Cork Company for similar purposes.

A complete description of all samples is given in table 1.

The program was started in May 1972 with the installation

at NBS of the second Flooring Radiant Panel in existence. (For

the purposes of brevity, the first panel made, which is now in

operation at the Armstrong Cork Company's Research and Development Center in Lancaster, will be referred to here as AFRP-1

while the second which is in operation at NBS in Gaithersburg,

Maryland will be called AFRP-2.) Some design changes were

made in AFRP-2 for development purposes before construction.

These include a sample size increase from 5 by 32 inches to

20 X 100 cm (about 8 in x 39 in) in order to negate end and

edge effects; chamber length increase from 45 in to 54 in; and

the addition of a chimney 10 inches high and 4 in x 14 1/2 in

(internal size) over the exhaust port. A picture of the apparatus in its present state is shown in figure 4. The front of

the chamber has been removed to expose the inner workings.

For Phases I and II, the instrumentation was modest

(figure 5). An instrument board was set up to control and

monitor the radiant panel inputs. Air supply rate was measured

by a rotameter on the instrument board. From the rotameter

4. TEST EQUIPMENT

6
the line goes through a gate valve and into the premix venturi.

A gas line goes through a shut-off valve, into a safety valve,

through a needle valve and into the venturi. The gas-air

mixture from the venturi flows directly to the radiant panel.

On a separate board are two rotameters for the pilot burner

supply lines. A dual pen recorder monitors a thermocouple

located in the exhaust end of the chamber (4 inches from the

chamber ceiling and 10 inches from the cold wall) on the one

channel and the voltage signal output of the smokemeter on the

other. A separate recorder reads the output from the pyrometer

focused on a 10 inch diameter circle in the center of the radiant

panel. When radiant flux measurements were to be taken, a separate duel pen recorder, along with a copper disk calorimeter

was employed.

5. NBS TEST PROGRAM

5.1. Phase I - Comparison With Previous Test Ratings

After a few preliminary tests run for the benefit of the

operator. Phase I was begun. The purpose of this phase was to

duplicate the condition of AFRP-1 in the AFRP-2 apparatus. The

chamber was blocked off at the 45 inch mark and all other

parameters were set according to the previously listed procedure.

First, open chamber incident heat flux measurements were

taken at various places along the sample surface using the

copper disk calorimeter. A dummy cement-asbestos board specimen with calorimeter locating holes provided at appropriate

intervals along the specimen center line was used to simulate

the sample surface. Point flux measurements were made by first

mounting the calorimeter at the desired location on the dummy

specimen in the specimen holder with the assembly outside the

chamber. The dummy specimen with calorimeter in place was then

moved into the chamber, the calorimeter output read within ten

seconds and the dummy specimen with calorimeter immediately

removed. Succeeding points on the flux profile curve were

determined in the same way. The results are shown in figure 6

along with results obtained earlier on AFRP-1. The comparison

was suprising since agreement to this degree was not expected.

Satisfied that a reasonable duplication of AFRP-1 had been

achieved, actual testing was begun. A total of 28 different

constructions were tested including 12 carpets, with and without underlayment , four resilient floor coverings, and two

samples of red oak. All samples, except for one red oak, were

backed by 3/8 inch asbestos board and 3/16 inch asbestos cement

board. The AFRP-1 procedure was followed as nearly as possible,

with the addition of flame front location versus time and smoke

determination.

7
Table 2 shows the results of this testing, and for comparison purposes the AFRP-1 results are also listed. It should

be remembered that all flame spread ratings are based on the

performance of red oak according to the schedule described

previously. The flame spread index shown for AFRP-1 was calculated based on red oak burning 32 inches in 27 minutes, while

for AFRP-2, the red oak burned 40 inches in 21.76 minutes. Red

oak has an arbitrarily assigned flame spread value of 100.

Even though there are many differences, nevertheless, the flame

spread ratings show a good correlation. The data can be divided

into two categories, those with a rating over 100 and those at

100 or below. For most cases the over 100 category is rated on

time and the 100 and under is rated on distance. It would not

be proper to compare the ratings based on time alone since the

samples are of different length and very few samples burn at a

steady rate over their entire length. On the other hand, it

has been seen that the input radiant flux to the samples is the

same at equal distances from the hot end of the sample. Thus,

comparison of the below 100 ratings should be meaningful.

In order to make this comparison, the AFRP-1 ratings were

converted to actual distances burned in centimeters regardless

of time. The easiest comparison to be made would be to see if

the results of AFRP-1 and AFRP-2 are linearly related. A least

squares regression analysis of the data indicates the best

estimated straight line for the data points shown in figure 7^.

The correlation coefficient of r = 0.94 indicates a high degree

of correlation.

The data agreement indicated here is good considering some

of the differences in test conditions. An attempt was made to

duplicate AFRP-1 in the construction of AFRP-2 for this comparison. However, there were nevertheless some differences.

For example, the exhaust port of AFRP-2 measured 4 in x 12 in

(48 in^) due to the installation of smoke measuring equipment,

whereas the AFRP-1 chamber makes use of a 7 in radius semicircular hole (77 in^). Also, the hood above AFRP-1 was apparently considerably stronger than that used with AFRP-2.

These differences did affect the test as is shown by an

analysis of an individual test. Figure 8 shows the results

for an acrylic carpet tested in both apparatus. Both flame

spread and chamber temperature rise are shown. Notice that

two phenomena are immediately evident. First, flame front

propagation was faster in AFRP-2. Second, the chamber temperature was considerably higher. These two phenomena were evident

in all comparison tests in Phase I, including red oak, and they

probably stem from the same cause - difference in air flow

through the two chambers.

See Appendix II - statistical analysis.

8
Although air flow measurements were not taken during this

Phase, from the physical conditions of the two apparatus, it is

evident that AFRP-1 should allow a larger throughput of air.

It has a larger exhaust opening, greater amount of inlet air

venting and higher draw from its hood. This excess air would

tend to minimize temperature changes. Also, more material is

burned since the specimen is about 8 inches wide for AFRP-2

whereas it is 5 inches wide for AFRP-1.

5.1.1. Comparison of Rating Performance

With Other Fire Test Methods

Despite the fact that AFRP-2 probably had a higher degree

of energy feedback and thus conditions were more severe, the

flame propagation distance still showed a high degree of correlation. This fact gives a boost to the radiant panel concept

since it indicates that a high degree of reproducibility may be

possible between two apparatus even if one is slightly more

severe than the other. At this time it was decided to determine if any correlation existed between the Phase I results and

results of other test methods. Chosen for comparison were

UL992, E-84, E-162, and the model corridor of Man Made Fibers

Producers Association (MMFPA) . Graphs of the common data

points are shown in figure 9 (the data is given in table 3)

.

As would be expected, little correlation is indicated with any

of these four test methods when all points are plotted. However,

when only the data points with AFRP-2 values equal to or less

than 100 are plotted, the correlation of MMFPA is better, but

still not as good as the AFRP-1. The table below shows the

correlation coefficient r calculated from the comparison data

on the four graphs as well as for the comparison between AFRP-1

and 2.

Model

Corridor

AFRP-1 E-84 E-162 ( MMFPA ) UL9 92

All data 0.94 0.39 0.54 -0.57^ 0.47

<100 0.94 0.45 0.29 -0.833^ 0.14

Notice the high correlation between AFRP-1 and AFRP-2.

The remainder of the comparisons seem relatively poor. In

truth there may be little reason why a good correlation should

be expected between any of the other four and the Flooring

Radiant Panel Test owing to their basic differences.

A negative value of r indicates an inverse relationship, the

strength of which is measured from low to high on a scale of

0.0 to -1.0.

9
5.2. Phase II - An Exploration of Various Test

Heating Conditions and a Study of the Rating Method

Phase II was to study alternative test conditions and to

improve the consistency of the test measurement and system

characteristics. First, the present comparative rating system

has raised questions. This is so, because it depends on the

burning characteristics of red oak; and furthermore, is based

on flame spread time or distance burned. The red oak standard

can produce problems with reproducibility and the dual character of the measuring index yields two independent qualities

of the material. Second, the level of radiant flux produced

by the panel as well as extraneous heat transfer to the specimen from the chamber is an area that needs examination. In

principle the external heat transfer to the specimen should

be reasonably steady during a test.

Based on the fundamental ideas from which the test was

designed, distance was chosen as the rating basis. The reason

for this can be seen in a review of figure 1, the room fire

situation. It is of more significance to know how far a fire

will be propagated rather than how fast. Speed of flame front

propagation will be a factor only if the flooring will propagate the fire a great distance. With this idea in mind, one

criterion selected was that the test condition would be such

that only flooring with the very worst surface flammability

properties would propagate fire to the full sample length

(100 cm) . Other samples would burn some shorter distance and

extinguish.

Another criterion was that of repeatability. In Phase I,

of all replicate sets of samples tested, the average percent

coefficient of variation was 9.9 if all data are considered

and 8.8 if only those points under 100 are considered. This

would be adequate repeatability and any changes in the test

conditions should not cause the repeatability to be poorer.

Finally, the last criterion to be considered concerns

relevance. As has been noted earlier, judging relevance can

only be done fully with a knowledge of full scale results.

However, a new test method should be at least qualitatively

consistent with existing tests, common sense, and experience.

For example, experience, and previous testing as well as common

sense, says that a carpet in a flammability test should perform more poorly when used with an underlayment pad than when

used directly over a substrate that has a relatively higher

heat sink value, such as asbestos cement board. It should

be expected, then, that carpets tested over underlayment

pads should receive poorer ratings than the same carpets

tested over asbestos cement board. In addition, the test

conditions should generally reflect conditions that are typically encountered in a full scale fire situation with regard

to energy inputs and sample configuration.

10
In summary, the three chosen criteria for Phase II were:

1. The flame front on all but the poorest flooring

tested should extinguish before reaching the end

of the sample. Furthermore, assuming that the

samples selected for this study were randomly

chosen, there should be a normal distribution

among extinguishment points from about 10 cm

to 100 cm.

2. The repeatability of the test under any new set

of conditions should be no worse than that found

in Phase I.

3. The test results should be at least qualitatively

consistent with experience, previous testing,

and common sense, or any major deviations

accounted for.

Criterion 1 would be the immediate goal with the remaining

ones to be tested subsequently.

5.2.1. Test Operation at Several Thermal Conditions

The underlying plan in this phase of work was to select

three sets of test conditions which would include one set that

was very severe and one set that was rather mild. Testing a

skeleton series of flooring on each of these sets would allow

a further narrowing of the field to one set of conditons.

Next, the complete series of flooring would be tested at these

conditions. If the results of this testing met the chosen

criteria, the Phase II goals would be met. However, minor

changes may be indicated and these would be made with some

minimum amount of retesting for confirmation. If at this time

the criteria could not be met, then the entire process would

be repeated using conditions obtained by varying different sets

of parameters.

Chosen initially to be varied were the following three

parameters (see figure 10)

:

1. Panel temperature

2. Panel to sample angle

3. Panel to sample distance (minimum)

In order to have some guidelines in the selection of the

three trial sets of conditions, seven different preliminary

sets of conditions were set up on the apparatus and sample

surface radiant flux measurements taken. The results of those

measurements are shown in figure 10.

11
Before the test conditions were determined, the exhaust

port was changed from its original opening of 4 in x 12 in

(48 sq in) as used in Phase I to 4-3/4 in x 16 in (76 sq in)

as designed. This opening was used for all subsequent tests

in AFRP-2.

On a set of experimental tests in the MMFPA Model Corridor,

a typical carpet sample requires about 0.3 watts/cm^ to maintain a flame front [5]. In addition, in Phase I testing, the

average distance where flame front extinguishment occurred

corresponds to an incident flux of around 0.3 watts/cm^. This

fact provided a benchmark in the choice of conditions.

The three sets of conditions chosen are shown as A, B, and

C on figure 10. The reasons for their choice centered around

their relationship to the 0.3 watts/cm^ line. Condition A

has almost no points below 0.3 watts/cm^; thus it is quite

severe. Condition C has over 50 percent of the sample surface

receiving less than 0.3 watts/cm^ and this condition should be

mild enough so that very few samples will burn to the full

sample length. Condition B is some midpoint between A and C

having about 40% of the sample surface under 0.3 watts/cm^.

Notice that Condition A differs from Condition D apparently only in panel to sample distance. Condition D was that

condition tested in Phase I. It was at this point that the

importance of another parameter became evident, that of initial

chamber temperature as measured by the chamber thermocouple.

Originally it was thought that steady state initial chamber

temperature was a function only of the panel temperature.

However, under Condition D in Phase I the initial chamber temperature was about 227°C, while under Condition A, the chamber

temperature was only 197°C. The reason for the difference is

in the total air-gas flow volume to the panel. In order to

keep the same panel temperature and increase the chamber temperature, all that needs to be done is to increase the total

volume flow to the panel without altering significantly the

air to gas ratio, which essentially determines the panel

temperature.

The next step in Phase II was to test a selection of

flooring covering a wide range of flammability under all conditions for comparison. At first eight samples were chosen

and tested under Condition A - panel temperature at 670°C,

initial chamber temperature at 197 °C. For Condition B - panel temperature at 550°C and chamber temperature at 172 °C,

and Condition C - panel temperature at 490°C and chamber

temperature at 144 °C, a few more samples were added to make a more complete comparison. The results of this testing are

shown in table 4. Notice that all ratings are in terms of

distance burned (in centimeters) except in the case of those

12
samples which burned the full distance (100 centimeters) for

which the elapsed time to burn the full distance is given.

The incident heat flux at extinguishment is also shown. Also,

on this table the Phase I results are included in similar terms.

A graphical representation of the data, figure 11, compares

all the conditions as to distribution of ratings. The bar graph

shows the number of times a rating fell in the range listed on

the abscissa. The graph indicates that Condition C has a distribution of ratings that is reasonably spaced over the range

of possible ratings. In addition, under this condition, only

two samples out of 19 burned the full 100 centimeters. For

this reason. Condition C was chosen for complete testing and

the remainder of the series of 36 tests was run under this

condition. The results are shown in figure 12.

The last step in Phase II was to find out if the test results met the three criteria stipulated. First, out of 36

different constructions tested, only four burned the full 100

centimeters. Two of these four consisted of the only polypropylene carpet tested (0-1) , with and without an under layment;

the other two were a nylon (N-4) and a polyester (P-1) , both

with underlayment. The table below shows data from other types

of tests on these materials. No data were available for the

polyester.

AFRP-2 Time

to Burn 100 cm UL992 Index E-162 Index

0-1 84 minutes 2.1 616

0-1/pad 36 minutes 24.0 764

N-4/pad 73 minutes 11.8 253

Average of all

others 1.55^ 240^

Hi/Lo all others 0.9/2.6 64/400

These data indicate that these carpets have been considered poor, with the exception of specimen 0-1 by UL-992, by

the other test methods. Thus the first criteria has been considered to have been met. All but the poorest flooring in the

series extinguished before burning 100 cm.

^Arithmetic mean of the results of all tests except those on

0-1, 0-1 with underlayment pad, and N-4 with underlayment pad.

13
5.2.2. An Examinatiion of Test Repeatability

During testing at conditions A, B, and C a number of

duplicate samples were run for the purpose of testing lepeatability. A summary of that testing is shown in table 5. The

average percent coefficient of variation has been calculated

for replicate tests for each temperature. The average for the

entire set under a particular condition is found at the bottom.

The repeatability appears to be excellent for this type

of test. At 670°C the average percent coefficient of variation

is 5.5 and at 550°C the average percent coefficient of variation

is 5.8. Notice that in the replicate testing at 550°C on

wool (W-1) , there is one value that is grossly inconsistent.

There were no reported problems with this test. However, the

W-1 carpet has repeatedly performed unusually. For example,

when W-1 is tested under the panel at 490°C, it will not propagate any flame front without a three minute and thirty second

preheat, whereas under a 670°C panel, it will propagate quite

readily. Perhaps 550°C is at a critical point between preheat

necessary and preheat not necessary. If the unusual value is

discounted, the average percent coefficient of variation for

550°C panel temperature drops to 3.1.

The average percent coefficient of variation for all

samples is 5.3 if the unusual condition B W-1 Test is included

and 4.4 if it is not. This is well within the 9.9% achieved

for all samples in Phase I, and. below the 8.8 percent for the

partial sample. This data indicates that the repeatability

criterion of Phase II has also been met.

Criterion 3 states that the results should be at least

qualitatively consistent with experience, previous testing,

and common sense. A number of events point toward the fulfillment of this goal. First, in all cases, the addition of

a rubberized hair jute underlay increased the flame spread

distance of the carpet under test. Second, as can be seen in

a comparison of Condition C with the other three conditions

tested (A, B, and D, table 4) , a reduction of the panel and

chamber temperature reduces the flame spread distance in every

case but two, and one of these is the erratic specimen, W-1.

Finally, a comparison of Condition C with other test methods,

while not necessarily showing good correlation, should show

general agreement on flooring materials that are very good or

very bad. Figure 13 and table 6 show these comparisons along

with the regression line and correlation coefficients. It is

evident that the results of AFRP-2 are at least qualitatively

consistent with the four flammability tests listed. In addition,

comparing the correlation coefficients obtained in Phase I and

Phase II (figures 9 and 13) shows that the modifications made

in Phase II have significantly improved the correlation with

E-84 and UL-992, whereas, it was worse for E-162 and about the

same for MMFPA.

14
Model

Corridor

E-84 E-162 (MMFPA) UL-992

Phase I 0.39 0.54 -0.57 0.47

Phase II 0.73 0.24 -0.65 0.91

5.3. Smoke Generation

Although the Flooring Radiant Panel Test is primarily a

flame spread measurement test, nevertheless, a smoke density

measurement capability was designed into the apparatus. During

all testing, smoke generation, as measured by the smoke meter

located in the chimney, was recorded. Discussion of that data

is outside the scope of this paper. However, the data is on

file at the Armstrong Cork Company's Research and Development

Center.

5.4. Phase III - A Study of the Effects of

Variations in Test Procedures and Test Conditions

Phase III is a study to determine what effect changes in

some of the more important test parameters would have upon the

results. Toward this end. Phase III was divided into five parts

to effect the following studies:

Part 1 Study of the effect of changes in initial chamber

air temperature.

Part 2 Study of the effect of changes in ignition

procedure.

Part 3 Study of the effect of changes in air throughput.

Part 4 Study of the effect of sample conditioning.

Part 5 Study of the effect of changes in substrate.

These studies will give an indication of the ruggedness

of the Flooring Radiant Panel Test or how sensitive the results

are to some of the expected daily variations in test environment. These tests would also allow a prediction of how some

deviations in test operation procedure will affect the results.

15
5.4.1. Effect of Changes in Initial Chamber Air Temperature

In Phase I and II, the only temperature measuring instrument in operation during the tests was the chamber air temperature thermocouple centrally located 10 inches from the cold end

and four inches from the ceiling of the chamber. Also, during

Phase II it was discovered that, as has been mentioned above,

the chamber air temperature was not solely a function of the

panel temperature but varied with the total air gas mixture

throughput to the panel as well. Furthermore, the results of

the test also varied with the chamber air temperature. In

order to monitor the actual chamber wall temperatures j. ten

additional thermocouples were added to the chamber before the

start of Phase III. These thermocouples were embedded in the

outside of the walls deep enough to be within 1/16" from the

inside but not exposed. The locations are shown in figure 14.

To study the effect of differing chamber and panel temperatures a test schedule was set up which would allow testing

under two or three different initial chamber temperatures. The

schedule is shown in table 7. It covers essentially the entire

operating range of the apparatus in its present design. For

example, it is not possible to achieve a steady state chamber

air temperature as low as 172°C when the panel itself is at

670°C.

A test was conducted on each of the five materials under

each set of conditions in the schedule. ^ The flame spread

distance results of that testing are shown in table 8. These

results show that the radiant panel is by far the most powerful influence upon flame spread distance while the initial

chamber air temperature, which itself is influenced in part by

the initial chamber wall temperature, has a small but definite

effect.

Notice that there is a consistent anomaly in the results

which occurs under conditions 490/172 and 490/197^ in four

out of five materials. The flame spread distance is less with

condition 490/197 when that condition should be more severe.

Plots of chamber air and wall temperatures for the tests in

question do not show why flame spread distance should be more

under 490/172; nor do plots of heat flux versus location. The

answer may lie in the greatly increased panel "exhaust" flow

Some of these tests had previously been conducted in Phase I

or II and, in order to save time, were not repeated in this

study, but the earlier results used instead.

Since the test conditions are defined by two temperatures,

the panel temperature and the initial chamber air temperature,

the two numbers separated by the slash represent those temperatures. Thus, for a panel temperature of 550°C and an

initial chamber air temperature of 197°C, the designation

550/197 is used.

16
under 490/197 which may upset normal air patterns in the chamber and cause localized cooling on the sample. This theory

has not been tested.

During this study, the embedded chamber wall thermocouple

outputs were recorded. This allowed another study of the

involvement of the chamber walls in each individual test. In

the following table are given comparison temperature rise

difference data for four thermocouple locations under four

different conditions listed in order of increasing severity.

Conditions

Thermocouple

Location 490/144 490/172 550/144 550/197

Air max ATp=8°C 32°C 130°C 130°C

#1 0°C 10°C 27°C 38°C

#3 7°C 9°C 14°C 22°C

#10 2°C 8°C 26°C 38*^0

The numbers in each column are the differences between

the highest and lowest maximum temperature rises recorded at

that thermocouple in the first six minutes among all the tests

run under the conditions listed at the head of the column.

With increasing severity, all locations show wider differences

between the lowest and highest maximum. Since chamber energy

feedback has been estimated to contribute approximately 10%

of the incident energy falling upon the sample,^ the chamber

feedback can have a significant effect upon the flame spread

distance of a sample. Probably, however, the effect is only

noticeable under conditions at least as severe as 550/144,

above which the chamber temperature is significantly affected

by a burning sample.

5.4.2. Effect of Changes in the Ignition Procedure

In the next part of Phase III, the ignition procedure was

studied. As was mentioned before, during Phase II under conditions 550/144 the wool carpet (W-1) would not ignite without

a three minute and thirty second preheat. It was thought that

perhaps preheating could have a drastic effect on the flame

spread results of other materials as well. Also, to be studied

in this section was the effect of the initial rapid burn zone

Based on radiant energy "view factor" considerations.

17
on the final flame spread results. As can be seen in the graphs

of chamber air temperature in the previous section, with most

materia.ls there is an initial time, usually 0 to 7 minutes,

where the burning is completely under the influence of the

large output from the panel. This burning consumes a larger

percentage of the material and releases a much larger amount

of heat than under steadier state conditions later. The

question to be answered here is how would the material perform

if this initial stage were eliminated.

To conduct the first part of the study, six flooring

materials were selected and put through preheat tests. In

these tests, run under conditions 490/144 (panel temperature

490°C, chamber temperature 144 °C) all conditions for a normal

test were set. However, to prevent ignition with the introduction of the sample, the pilot burner was raised four inches

off the sample surface. At the end of the predetermined preheat period, the pilot burner was lowered until ignition

occurred and normal flame spread distance versus time readings

taken.

A number of different preheat times for each sample were

used. Figures 15 and 16 are a graphical representation of two

typical series of tests showing the effects of preheating.

Preheating appears to have only one obvious effect. It increases the rate of burning in the initial rapid burn zone.

(In some of the series, preheating does consistently increase

the total flame spread distance, but this is not true in every

case .

)

There does appear to be a pattern to the preheating effect.

After the initial rapid burn zone, the burning attempts to

follow a set pattern which is the extension of the line representing no preheat.

One possible explanation for this behavior is found by

considering elements of the sample far from the panel in the

region of typical extinguishment. During a normal (no preheat)

test, the flame front takes a definite amount of time to reach

this area. In this time, the area has received a given amount

of energy from the panel and from the flame front and has

exchanged energy with the chamber walls as well. However, in a preheat test, the flame front movement is delayed. By the

time the flame front reaches the area, it has received more

energy than before and is more likely to burn. The net result

is that areas further from the burner will receive enough

energy to burn. Of course, there is a limit to this effect as

the sample areas heat up and begin to come to equilibrium with

their surroundings.

18
This explanation has not been verified since it would take

a detailed analysis and energy balance of the system and that

is beyond the scope of this work. However, work in Phase IV

was done to provide heat transfer data that may allow an energy

balance to be made.

The testing of carpet A-5 (figure 16) brought about some

other interesting phenomena. Carpet A-5 is a white plush acrylic that can be rated average to poor (as to f lammability ) in

relation to the entire series of flooring tested. When the

preheating of carpet A-5 was attempted, on two different occasions the same phenomenon was noticed: at 5.0 minutes heavy

localized smoking occurred directly under the pilot burner

which also is the part of the sample receiving the most energy.

At 5.7 minutes, the gases from this region ignited as they

reached the pilot burner. The flame flashed back to the carpet

and sample ignition occurred. These two tests were the only

tests where auto ignition occurred and their flame spread

versus time plots are identical.

In order to keep auto ignition from occurring, the pilot

burner was moved 2 inches further from the sample. Another A-5

test was run with a planned 12 minute preheat. At 5.0 minutes

the smoking again occurred, and at 5.7 minutes, pyrolysis

products were igniting around the pilot burner but no flame

found its way back to the sample. A few minutes later, the

smoking ceased.

At the 12 minute mark, the pilot was lowered to the sample

but no ignition took place. Evidently enough of the combustibles had been pyrolyzed in the pilot ignition zone so that

there were none left to burn. A piece of rolled up chart paper

was ignited and touched to locations successively further from

the pilot in an attempt to cause ignition. Finally at 12.9

minutes and at 2 8 centimeters, the sample ignited and burned

as shown in figure 16. This is the only flooring that exhibited this behavior; however, under more extreme preheating,

others may be expected to perform similarly.

The second part of this study dealt with the effect of

moving the location of the ignition source. Taking a typical

curve from one of the graphs, for example, A-5, figure 16,

the plan was to cut off the bottom half of the curve and ignite

the carpet at 30 cm instead of 0 cm; after a 6.6 minute preheat. For these tests, that portion of the sample from the

ignition area to the pilot burner was removed. Comparison of

the resulting flame spread versus time curve with that of the

original test would give an indication of the importance of

the initial rapid burning zone.

19
The curves for these results are shown in figures 17-19.

Also on these figures are the preheat tests to which these

results should be compared. In the case of carpet N-2, the

initial rapid burning zone appears to have the effect of increasing the total flame spread (even though this zone has

finished burning for a number of minutes) . However, with the

resilient flooring R-3, the effect of the initial burning zone

does not increase final burn length. This was even more puzzling since R-3 releases more heat than any of the other

floorings tested in Phase II.

In summary, it appears as though the Flooring Radiant

Panel Test results are affected to a small extent by preheating.

In addition, at the low radiant heat input conditions that were

standard for the test, some amount of preheat may be desirable.

The reason lies in the difference in severity between the panel

and the pilot burner. Under more severe conditions such as

Condition A in Phase II, the panel was contributing a high

enough energy input to the sample to rapidly bring the area

near the pilot burner to pyrolysis before the pilot-induced

flame extinguished. However, under the reduced operating level

of 490°C, some materials (W-1) may not reach pyrolysis near the

pilot before the pilot-induced flame extinguishes. In this

case, when pyrolysis is finally reached near the pilot, there

is no ignition source and thus no ignition. However, a preheat

would bring the pilot burner region up to pyrolysis before

extinguishment of the pilot-induced flame.

Unfortunately, different materials heat up at different

rates; thus a universal preheat time is nonexistent. Moreover,

experience shows that a particular flooring material can warm

at a fast or slow rate depending upon the fiber composition.

It could be stipulated that if a material does not ignite and

burn to at least 4 cm upon introduction into the chamber, it

should be retested with a preheat of either 5 or 15 minutes

based upon whether it is a fast or slow "warmer". The time

factors given here are based upon the limited experience of

testing under the program. Further work on the Flooring

Radiant Panel may change these numbers or, in fact, eliminate

the need for any consideration of preheating.

In summarizing the displaced ignition tests, it can be

repeated that the initial rapid burning area does have an

effect on total flame spread distance although the mechanism

for this effect is not known.

20
5.4.3. A Study of Induced Air Flow Patterns

The third study in Phase III was a relatively minor study

aimed at the charting of air patterns within the chamber and

determining the effects produced by a gross change in the exhaust draft.

The first part of the study involved the use of titanium

tetrachloride to produce an indicator smoke that was sparse

enough to not disturb the natural air patterns but dense enough

to be easily seen. With the panel in operation and a piece of

asbestos cement board replacing the sample, indicator smoke

was traced in its path from a point at the 90 cm location on

the asbestos cement (point 1, figure 20) until it exited the

chamber. The incoming air at the end of the sample was found

to move along the sample, reaching the 50 cm point (point 3) in

about eight seconds. It continued along the sample until it was

under the panel, where it was picked up by convection currents,

followed the face of the panel and went out the chimney (point

2) . The entire journey from point 1 to the chimney took about

25 seconds.

The top view on figure 20 shows how the smoke drifts toward the back wall side of the panel. This phenomenon is in

accord with other occurrences noticed in earlier testing. For

example, after about 100 tests, the samples began to burn more

readily on the side toward the wall. In an attempt to determine why this was happening, it was discovered that the effluent from the pilot burner strikes the panel on the near wall

side and hinders burning. As a result the back wall side of

the panel is hotter.

Next, air and smoke patterns were observed under actual

testing conditions. Duplicate samples underwent the test. In

the first test, the exhaust hood was in normal operation. Air

flow velocity was intermittently monitored in the center of

the chimney. In the second test, the exhaust hood gate was

partially closed reducing the velocity of the air in the chimney about 12 percent. During this test, the titanium tetrachloride indicator was applied at the 90 cm point and its

progress monitored. After both tests, a velocity profile was

taken across the chimney. Figure 21 shows the results of air

velocity measurements as well as the comparison of flame spread,

maximum chamber temperature, and maximum smoke generation^ results for each test. The material tested was the acrylic carpet A-5 which normally will burn out to 60± 2 cm. Thus it is

The smoke generation number is calculated as follows:

It

S = log — where 1-^., I^ is the output from the smokemeter

without and with smoke present, respectively.

21
evident that the decreased air flow had an almost negligible

effect upon the burning characteristics. It is true that 63

is outside of the previously established error limits; however,

it is only 5% from the mean value and therefore the difference

is not considered significant.

In figure 22 are observations of the air and smoke patterns

during the second test. An unusual aspect was observed at 3:30

when the flame front had reached 40 cm. The TiCl^ indicator

gas, after flowing down the sample, appeared to pass straight

through the flame front plume without altering its direction

in any way. This phenomenon continued for the remainder of the

test. Although the smoke produced by the flame front followed

its normal pattern of heading toward the panel and then out to

the chimney, the TiCl4 indicator flow seemed to be unaffected

by the existence of the flame front.

5.4.4. Effect of Specimen Conditioning and Wear

Approximately one month before these tests were to be conducted, two sets of five samples each were selected for moisture content testing and a set of three samples set aside for

wear testing. One set of the moisture content samples was

placed in a sealed bag containing calcium sulfate drying crystals and the other set placed in a sealed bag containing a

beaker of water. Also into the bags were placed 2 in x 2 in

squares of each sample that had been previously weighed. The

bags were undisturbed for 30 days. At the end of that time,

the bags were opened, the small squares weighed and the samples

tested. The percent moisture content^ by weight based on weight

of bone dry sample as well as the flame spread results of the

testing are shown in table 9. Notice that the percent moisture

content of the samples did not vary drastically.

The results of this testing indicate quite clearly that

moisture content within the range studied is not a factor in

the flame spread of these samples.

A limited study of the effect of specimen wear characteristics was conducted. The three samples set aside for wear

testing were mounted side by side on the floor of the room

housing the radiant panel apparatus in a high traffic area.

After two weeks, the samples were quite dirty but were left

down for an additional two weeks. At that time, they were

removed from the floor and tested, and the results are also

shown in table 9. Samples N-3 and A-4 showed no difference in

flame spread results but A-5 actually increased in flame spread.

It-, j. ^ J. ^ weight of moisture ^Percent moisture content = :

,^ , = =— x 100. weight of bone dry sample

22
It was thought that soiling of the flooring would lowei: the

f lairanability simply by physical hindrance of heat transfer to

the unburned parts of the sample. Of course, this depends upon

the composition of the soiling agent, but since all three

samples received the same exposure to foot traffic, this is

probably not the factor. Another possibility is that some

samples are not as highly emissive as is commonly thought. In

this case, addition of soiling may change the emissivity and

thus energy absorption.

5.4.5. Substrate Study

The final part of Phase III was a study of the effect of

substrate variation. This study is important inasmuch as it

is commonly known that substrate has an effect upon surface

flammability due to the amount of energy that the surface may

lose through the backing and also in some cases, by the fuel

that it contributes. In effect, a different "substrate" had

already been tested in Phase II when underlayment was used.

In this section, studies involved the use of substrates that

should have more subtle effects.

A series of tests were run using four different flooring

samples. Three of the four were tested over two different

substrates, 3/8 inch plywood and 3/8 inch asbestos cement

board, with and without adhesive.^ For these three samples,

then, there were actually six different substrate systems

including the regular substrate used in Phase II and that substrate with an underlayment. The fourth flooring, due to lack

of sufficient number of samples, was only tested over plywood

without use of adhesive.

The results are shown in table 10. As had been predicted,

the substrate did make a difference. The plywood, being a

poor heat sink, kept the heat on the surface. In addition,

depending upon the time duration of the test, the plywood

actually became involved in the burning and contributed heat.

Both of these factors result in greater flame spread. Notice,

however, that carpet A-5 did not show an increase in flame

spread as did the others. In addition, with the use of

asbestos-cement board, A-4 and P-1 reacted as expected and had

lower flame spread; however, again A-5 was not affected. An

understanding of this phenomenon may be gained by looking at

the test duration time column on table 10. In this column are

The adhesive used was a latex base floor covering adhesive.

It was applied to the substrate at 50 grams/ft^ wet coverage.

The carpet was then applied. The samples were allowed to

air dry for 1 week and then put into a 110 °C oven for 24 hours

after which they were allowed to come to equilibrium in a controlled environment room 75 °F, 50% RH for 72 hours.

23
listed the test duration times for the norm test. In the next

two columns are listed the minimum difference between results

for the various substrates. The longer the test duration time

the more the flooring is affected by the substrate. There is

much support for this idea. If a material burns rapidly,

chances are that the heat flow has not had an opportunity to

penetrate a great distance. Thus the composition of the substrate would tend not to be a factor. On the other hand, where

test duration time is long, more of the sample will be heated

down to the substrate, making the substrate itself important.

Finally, consider the effect that use of the adhesive has

upon results. Except for A-5, use of the adhesive results in

10 to 2 0 percent reduction in flame spread. To a great degree,

this is probably the result of the better surface contact between the sample and the substrate provided by the adhesive and

also, to a smaller degree, it is the result of the moisture

content of the adhesive. The moisture content may not be important in the initial rapid burning zone, but out near the

end of the burning region, when the flame front is small, it

may be a factor.

5.4.6. Summary of Phase III

Phase III was a study of changes in test conditions. The

purpose of this study was not to determine how gross changes

in the apparatus or sample will affect the results. Rather

its purpose was to see how sensitive the test is to minor

fluctuations that may be encountered in day-to-day testing.

It was assumed that if the Flooring Radiant Panel Test gains

acceptance in the field, with it must come a typically stringent set of test procedures, specimen conditioning procedures,

reporting procedures, etc. We assume that under proper conditions, these procedures will be followed. Therefore, all

that can be asked of a test method is that if the proper procedures are followed, the test should be accurate in its

measurements. It must not be overly sensitive to test condition variations that can occur even if the procedures are

followed.

Therefore, this phase was aimed at those smaller scale

changes such as humidity changes of the conditioning room from

35% to 65%, small (±5°C) changes in panel or chamber air temperatures, or soiling of the sample. These variations can

occur and the Flooring Radiant Panel Test has shown that even

with these variations, a high degree of repeatability can be

expected.

24
Finally, the matter of the substrate was studied. It was

found that the substrate can have a drastic effect upon the

results. Therefore, in light of the fact that the Flooring

Radiant Panel Test is a relatively inexpensive test to run, it

is reasonable to expect that flooring should be considered as

existing in a system, and not alone; and that the entire system

should be tested, not the surface portion alone. This would

mean that in order to be rated properly, a flooring material

would have to be tested over all the possible substrates over

which it is typically used. This would be something completely

new in fire hazard testing but it is easily seen how much

confidence it would give to fire hazard ratings. Of course,

after a log of testing had been built up, knowledge of heat

transfer mechanisms and constants related to the substrates

would allow predictions and interpolations to reduce the number

of required tests. This approach would be similar to that used

now in fire endurance testing of floor and roof-ceiling structures .

5.5. Phase IV - Study of Thermal Conditions During Burning

The original plan for Phase IV called for a wrap up of the

one year testing program in addition to any supplemental work

that may have been found to be needed during the year. Fortunately, the program was completed by the end of the third phase.

Therefore, the fourth phase was involved in making measurements

on the apparatus during testing for the purpose of providing

data for research on surface flammability and also for possible

correlation with current corridor work. These measurements

consisted largely of heat flux measurements through the sample,

through the walls, and to the sample surface. The analysis of

this data is largely outside the scope of this work; however,

some of the more general results will be presented here.

5.5.1. Heat Flow

The first work done in this phase involved measurement

of conductive heat flow through the chamber walls and sample.

For this study six ceramic heat flux meters were used. These

heat flux meters are the differential thermopile type with

temperature correction. Two of them were cemented to the wall

directly between thermocouples 1 and 3 and between 3 and 6 (on

figure 2 3) . Another one was cemented in the middle of the

ceiling 12 inches from the cold end. These three were spray

painted flat black to match the emissivity of the surroundings.

Another three were cemented to the 3/8 inch asbestos board

(which is the standard substrate) at the 30, 50 and 70 cm

locations so that with the installation of the flooring, they

would be in place between the flooring and the substrate.

25
Recordings of heat flux and temperature were taken every 5

seconds for the duration of four tests. The heat flux data

for one of these tests on A-5 is graphed on figure 24.

The phenomenon of importance here is the significance of

heat transfer through the substrate. At 30 cm, the sample is

receiving about 0.76 watts/cm^. From the graph it is evident

that the transfer through the substrate at this point levels

off at about 0.17 watts/cm^ until the flame front passes over.

Then it can shoot up to four or five times this value. (Unfortunately the data at the peak was lost.) However, if this

curve is similar to the curve for the heat flux meter at 50 cm,

the peak might have reached as high as 0.85 watts/cm^ . Even

when the flame front passes to within 4 inches of the wall

heat flux meter, the transfer to the wall only reaches 0.12

watts/cm^. This fact reinforces earlier conclusions about

effect of chamber involvement as well as the effect of substrate involvement.

In the second series, use was made of three SchmidtBoelter type total incident heat flux sensors. These sensors,

which record all incident heat flux no matter what the mechanism of transfer, were located at 30, 50, and 70 cm at the

sample surface (see figure 23) . In addition to these, the

pyrometer used to monitor the panel temperature readings was

relocated to the back of the chamber (location P, figure 23)

so that panel temperature readings could be made during the

test.

Figure 25 shows graphs of the results of one of the tests

(Carpet A-5) . Notice that the temperature of the panel appears

to skyrocket with ignition. Actually, it has been noticed that

upon removal of the sample tray immediately after a normal test,

in Phase II, the panel was settling down from higher temperatures, as much as 20°C higher as measured by the pyrometer.

However, skepticism arises as to whether the panel temperature

was actually reading 660°C.

One check of the panel temperatures lies in the reaction

of the heat flux sensors to the panel. The energy exchange

between the panel and the heat flux sensors varies according

to the formula

q ^=oAe F (T^-T^^). net s ps ps pp s where,

q^g^ is the net transfer of energy from the panel to the heat

flux sensor,

a is the Stefan-Boltzman constant

26
A is the area of the sensor

s

e is the interchange emissivity (related to the surface

characteristics of both the panel and the heat flux

sensor)

.

F is the view factor (related to the geometry of the system)

.

ps

T ,T are the temperatures (absolute) of the panel and the heat

^ flux sensor, respectively.

Fortunately, the product A^e^^ is nearly constant throughout the test and is small enough when compared to Tp that

its fluctuations can be discounted, since the senors are water

cooled. In addition, F is constant for a particular locaps tion. Thus

,

q ^ kT ^ where k = A e F ^net p s ps ps

If the panel is actually reaching a maximum, then the energy

transfer to the heat flux meters should increase according

to the ratio: —["^nf rr^ax (or min) ^ ^"^p , max (or min) . ^ = = HFS ^ Ratio

rip "I 4 p, steady state '^Pf steady state

The actual ratios for the three tests at points where the apparent panel temperature went through a maximum or minimum

(and the flame front had not reached the first heat flux meter)

are as follows:

Test

T

P

Steady State

T

.P Maximum

( T

Ratio)

Ratio

HFS@30

Ratio

HFS@50

Ratio

HFS@707

193 773°K 943°K 2.13 1.77 1. 49 1.45

194 773°K 713°K 0.73 0.93 0.95 1.00

195 773°K 838°K 1. 39 1.41 1. 32 1. 37

Obviously, the three tests show three different situations.

Test 195 shows consistent results. The apparent panel temperature went through a maximum with buildup of the flame front

and this maximum was reflected in the energy transfer to the

heat flux meters. However, in test 193 the apparent panel

temperature went through a maximum that was not followed by

^HFS - Schmidt-Boelter type heat flux sensor

27
the heat flux meters while in test 194, a minimum was reached

by the apparent panel temperature which also the heat flux

meters did not follow. As for the maximum seen in test 193,

a check of the log book for that test shows the operator noted

a plume which was high enough to be in the pyrometer's view.

This may have resulted in a false high reading for the panel

and, in fact, the inconsistently high reading for the HFS

ratio at 30 cm could also have been the result of the plume's

proximity.

The low values noticed in test 194 are a little more difficult to explain. Smoke obscuration is one possibility, but

the smoke charts show that the W-1 carpet in test 194 produced

almost no visible smoke. However, the effect of CO and

which is present in most hydrocarbon burning, may have been

overpowered in tests 193 and 195 by the heavy particulate smoke

production which, when it reached the face of the panel, became

a thermal emitter. But in test 194, the particulate production

being absent, the absorbing affect of CO and CO2 would become

evident and cause the pyrometer to read a lower temperature.

In any case, the question can be much deeper than we have

presented here and is thus beyond the scope of this work.

One other phenomenon of importance from this graph is indicated by the line representing heat flux to the sample at 70

cm. Although this point is never reached by the flame front,

it is nevertheless affected by the burning that does take place.

Even toward the end of the test, the incident heat flux at this

point is 20% higher than that at the start of the test. This

supports the observation in Phase III that the initial stages

of burning do affect the latter stages.

Again, the work of Phase IV was much more extensive than

is described here. On file with the author is the bulk of the

raw data which includes chamber wall temperature and heat flux

readings, sample temperature and heat flux readings and panel

temperature readings taken on a number of samples. This data

will be put to use in more detailed analyses of the Flooring

Radiant Panel Test some time in the future.

6. REVIEW

With the completion of Phase IV, the year long development program at NBS was brought to a close. The primary goals

of the program were met. The Flooring Radiant Panel Test,

originally developed by Armstrong Cork Company, was brought

further along in its development to the point where it has been

considered by NBS as a possible successor to E-84 and E-162

as the standard test for floor covering. In addition, developmental work on the test has provided a wealth of data that

28
can be of value in the general understanding of flooring flammability.

6.1. Test Apparatus

Of course, the project should not stop here. In any

program not brought to total completion, there must be plans

for future work. During this year, a number of situations and

problems arose which were side-stepped for the benefit of the

overall program. Generally, these problems were not of a nature

significant enough to warrant program delays, but their solution

can easily be incorporated into future work.

Perhaps the most significant of these problems is the

radiant panel itself. At present, the panel is a gas fired

refractory mounted into a steel housing. This arrangement leads

to the following problems:

1. It is a delicate structure easily damaged, and

difficult, expensive, and time-consuming to repair.

2. Panel warm-up takes from 1/2 to 1 hour even after the

proper gas/air intake settings are known.

3. There is a limited range of operating temperatures.

4. The quality of the burning, i.e., temperature variations with location on the surface is affected by

events within the chamber such as sample burning and

pilot burner effluent.

5. The temperature is difficult to control and measure.

6. Extensive safety equipment is required.

The above problems did not prevent the completion of the

program, rather they caused delays, lowered the total number of

tests that could be run on a daily basis, limited the scope of

the program, and possibly increased the repeatability error

limits. The author feels that an electrically heated panel

would solve many of the above problems and create no significant new ones. It would be more versatile and definitely an

overall asset for experimental and developmental work.

Another problem area is the wall material. At present,

the two Flooring Radiant Panel Tests in existence make use of

a mineral-base acoustical material. This material, while being

an excellent ceiling material, is rather unsuited for use as

a test enclosure. Its main drawback is its brittleness and

susceptibility to damage. Replacement of this material with

asbestos cement board, gypsum, or some combination thereof,

would surely solve this problem.
There are some other construction changes which can be

made in the apparatus. For example, a smaller door would allow

easier sample mounting techniques. Perhaps a quick clamp mechanism would help.

6.2. Flame Spread Index

The above-mentioned problems all involve changes in the

apparatus. Future work may also lead to improvements in the

method of flame spread rating.

At this point, the suggested flame spread index is the

distance the material burns until extinguishment. In order to

attach more physical significance to the rating it was suggested that, since each point along the sample surface corresponds to a given incident flux, the ratings be converted into

flux readings. The physical significance of this idea is that

the flux value corresponding to the extinguishment point for

a particular material can be said to be the material's minimum

required (critical) flux for flame front propagation.

This approach requires that the true total incident heat

flux be known at every point along the sample surface just

before extinguishment in all tests. Let us assume, for example,

that the true flux is known for a blank test, under steadystate conditions. Then, the only factors that will alter that

flux are changes in the panel temperature, changes in the

chamber wall and air temperatures, or physical obscuration of

the energy sources (smoke)

.

First of all, we can eliminate physical obscuration as a

factor since in no cases has it been reported in a Flooring

Radiant Panel Test that there was even a trace of smoke at the

time of flame front extinguishment. Smoke production always

happens well ahead of extinguishment. By the same token,

changes in panel temperature can be discounted by similar

arguments. What remains then is the accurate determination

of how incident flux to the sample is affected by changes in

the chamber wall and air temperatures. This can be determined

either by empirical measurement or by calculation. In fact,

as a check on the incident flux measurements of Phase II, the

theoretical flux measurement at 25 cm under Conditions C of

Phase II were calculated. This calculation took into consideration panel and wall temperatures and their appropriate

emissivities and view factors. While the measured value at

that location was 0.66 watts/cm^ , the calculated value was

0.6 5 watts/cm^ of which about 5% was contributed by the chamber

walls.

30
Thus, when the actual flux is known for any chamber temperature, then the "critical" flux can be determined by running

a standard Flooring Radiant Panel Test. And, in addition, we

have not allowed for the possibility that the chamber wall

temperature fluctuations are not significant enough to affect

the test. Since the chamber contributes only about 5% to 10%

of the total energy under conditions of a low (490°C) panel

temperature, this may be true.

As a check on the above idea, this "critical" flux of

seven different materials (neglecting wall temperature effects)

was found under conditions 670/197, 550/172, and 490/144 (Phase

III) .

Critical Radiant Flux W/cm^

Conditions A2A4A5N-3 N-4 W-1 R-3

670, T =197

ca

0.28 0.36 0. 24 1.40 0. 35 1. 35 0 . 36

T =P

490, T =172

ca

0. 31 0.43 0.23 1. 10 0. 27 0.61 0 . 35

T =P

490, T =144

ca

0. 29 0. 38 0.23 0.85 0. 25 0.60 0 . 42

These data show surprising correlation except for N- 3 and

W-1 for which no explanation is offered, indicating that a true

critical flux may be a simple value to measure in the Flooring

Radiant Panel Test.

Of course, critical flux is only one factor in the flammability of a material. Also to be considered are heat release

and speed of flame front propagation, and at this point no one

can say which facet is most important or what is the relative

importance of each.

31
APPENDIX A. THE ARMSTRONG CORK

COMPANY FLOORING RADIANT PANEL DEVELOPMENT

A.l. Test Parameter and Apparatus Design Criteria

Since fire is very complex, some difficulty was encountered

in selecting the proper parameters for the test. The selection

of the temperature at the hot end of the specimen offered some

problems, since it was desired that the temperature be hot

enough to ignite all specimens and also high enough to equal

flame temperatures encountered in a full-scale fire. Therefore, a temperature of 950 °F without a pilot burner was

selected. The selection of this temperature was based in part

upon a corridor test performed by the Forest Products Laboratories reported in a paper, "Effect of Wall Linings on Fire

Performance with a Partially Ventilated Corridor," where maximum temperatures on hardwood floors in three tests were recorded

at 630°, 805°, and 780°F. A paper by L. W. Sayers in Textile

Institute and Industry [1] , 1965, (Eng) reported ignition

temperatures of fibers determined by a hot-plate method such

as: cotton, 400°C (725°F); nylon, 530°C (987°F) ; triacetate,

540°C (1,004°F); acrylic, 560°C (1,040°F); polypropylene, 570°C

(1,058°F; and wool, 600°C (1,112°F). C. H. Yuill also reported

in his paper "Floor Coverings---What is a Hazard?" maximum

floor temperatures in the range of 1,100° to 1,400°F in some

room burnout tests. Based on this information, with the use

of a pilot light, the maximum temperature at the hot end of

our test specimen would be 1,600°F.

It was also desired that there be a uniform temperature

gradient down the full length of the test specimen. This was

found by measuring the temperature every one inch with thermocouples attached to the surface of an asbestos millboard and

setting the angle of the panel at 30°. The radiation intensity

at the sample surface (at the hot end) was also measured and

found to be 8,150 Btu/ft^ hr (2.55 W/cm^).

Preliminary tests showed that draft control is important

for reproducibility and the burning of the specimen. In enclosing the apparatus, make-up air is required; but it should

not cause excessive drafts, yet it should be sufficient to

supply enough oxygen for complete combustion of all specimens.

Available literature indicated that polypropylene would require

the most oxygen for combustion. Therefore, 4 inch high openings were made at both ends of the chamber, supplying air at

a velocity of approximately 50 ft/min. Since the width of the

chamber (20 in) is wider than the specimen (5 in) this air is

easily dispersed within the chamber without causing a direct

draft in one direction across the flaming specimen.

[1] Sayers, L. W. , Flammability of Fibers, Fabrics and

Garments, Textile Institute and Industry, Vol. 3, No. 7,

168-171 (July 1965)

.

32
The opening in the top is large enough to remove all of

the smoke and heat without causing abnormal draft across the

specimen.

A. 2. Armstrong Test Apparatus

The apparatus consists of a 12 in x 18 in gas fired

refractory radiant panel (same as in E-162) inclined at a 30°

angle over the exposed 5 in x 25 in portion of the horizontally

mounted test specimen, see figure 2. The specimen surface is

3-3/8 in below the lower edge of the panel. The panel and

adjustable height specimen transport system are enclosed in a

19-1/2 in x 26-1/2 in x 45 in, 5/8 in thick asbestos millboard

sheathed chamber with provisions for a free flow of draft-free

air to simulate natural burning conditions, see figure 3. The

end openings are 4 in x 19-1/2 in. The exhaust port (top) at

the cold end is a 7 inch diameter semi-circular hole. There

is a 4 in X 36 in VYCOR glass test viewing window in the front

face of the chamber. Below the window is a panel which can be

opened to facilitate placement and removal of the test specimen

via a drawer-like transport assembly.

The gas fired radiant panel is capable of operating at

temperatures up to 1,500°F with natural gas (nominal 1,000

Btu/ft^/min) . The gas and air are mixed at approximately

atmospheric pressure in a venturi. Air is supplied by a centrifugal blower capable of delivering 100 ft^/min at 3.2 inches

of water. When properly adjusted the burner has a blue flame

1/8 inch long with only a few short flashes of luminous flame.

The operation and adjustment of this burner is identical to

the one described in ASTM E-162. A radiation pyrometer is

used to monitor the black body temperature of the panel. A

chrome 1-alumel thermocouple 4 inches from the top and 10 inches

from the cold end of the chamber measures temperatures during

a test.

A 48 in X 36 in x 11 in exhaust hood with a 6 inch diameter

duct removes smoke and heat from the chamber. Its volumetric

capacity is approximately 3,000 ft^/min.

A. 3. Armstrong Test Procedure

1. Ignite the gas/air mixture passing through the radiant

panel and allow the unit to heat up for approximately 1/2

hour. Before each test, the panel should be checked to

maintain a temperature of 1,238°F ±7°F and adjustments

made to the gas if necessary.

33
2. Ignite the pilot burner and adjust the flame to its proper

length. The pilot burner is not extinguished between tests.

3. The temperature in the chamber before each test should be

approximately 460°F, but this may vary slightly from one

apparatus to another. This temperature will be established

after a number of tests have been conducted. Adjustments

are made with the sample base removed from the apparatus.

NOTE: It is recommended that a sheet of asbestos millboard be used to cover the opening when a hinged portion

of the front panel is raised and the base of the chamber

removed. The millboard is used to prevent heating of the

base and the operator when the front panel is open.

4. Invert the sample holder on a workbench and insert the

specimen, then the desired underlayments and substrates,

and finally the millboard. Place the five channel-iron

clamps provided across the back of the assembly and

tighten firmly into place with the wing nuts. Raise the

sample holder with the specimen assembly, vacuum the surface to remove any foreign particles; and if the specimen

is a carpet, brush the surface of the carpet to raise the

fibers to their normal position. Place the assembly onto

the base and fasten the assembly using the four threaded

studs in the base.

5. Remove the millboard sheet, slide the base containing the

specimen into the chamber, close the hinged flap, and

immediately start the timer.

6. Record the flame spread by noting the time and flame front

passes each 1 inch mark and any other observations such

as melting, blistering, penetration of the flame to the

substrate exposing backing, etc.

7. The test is continued until the flame front reaches the

end of the specimen or the flames extinguish themselves.

8. When the test is completed, the hinged flap is raised, the

base and specimen are pulled out of the chamber and the

millboard shield is put into place. The specimen and

rack can be cooled with wet towels or water. The sample

holder is removed from the base and preparation made for

the next test. Allow the chamber to cool to 460°F or to

the base temperature determined for the particular apparatus .

9. Since the temperature of the radiant panel will increase

slightly during the test, its temperature must be checked

and a slight adjustment made to the gas. Fifteen to twenty

minutes are required to cool the chamber and the radiant

34
panel between tests. This will depend upon the length

of the previous test.

10. Calculate the flame spread index as follows:

a. If the specimen burns the full sample length in less

time than it takes red oak to burn that distance

FSI = X 100

s b. If the specimen burns the full sample length in a longer period of time than it takes red oak, or if

the specimen does not burn the full sample length

D

FSI = — X 100

L

where FSI = flame spread index

L = specimen length

Tj^Q = time for red oak to burn full sample length

= time for specimen to burn full sample length

= distance specimen burns in time T^^^, or

flame spread length

11. Report the results, the observations with a complete

description of the test specimen, and also the test

assembly.

35
APPENDIX B. STATISTICAL ANALYSIS

B.l. Correlation of Test A with Test B

In this paper, in discussing the correlation of one test

result with another, least squares regression is used. To

determine the best straight line approximation of the data

points, the following formula is used

y = 3^x + ^2

3-, =

n n n

n Z x.y. - ( E x.)( E y.)

1=1 1=1 1=1

n n

nEx.2 -(Ex.)2

i=l ^ i=l

'2 = Y

- 3i X

y, X are mean values of y and x respectively

n is the number of data points (sample size)

To determine the value of the correlation coefficient, r, which

is a measure of linear correlation, the following formula is

used

r =

n

E i=l

(x-j^ - x) (y^ - y)

n _ n

E (x - X) 2 E (y. - y) 2 Li=l ^ i=l ^ 1/2

The correlation coefficient is of significant value in this

work because, as can be seen from the formula used to calculate

r, it does not depend upon whether x or y is plotted on the

horizontal axis. Physically, this means that the correlation

coefficient is not concerned with dependency of y upon x but

only with relationship . And since in this paper, we are interested in relationship, r is a useful quantity.

This coefficient varies from -1.0 to +1.0 and the strength

of correlation is equal to the absolute value of r regardless

of sign. In other words, a value of 0 for r indicates no correlation whereas a value of -1.0 or +1.0 indicates perfect

correlation. A negative sign merely indicates that the correlation is inverse.

36
References

[1] Surface Flairanability of Materials: A Survey of Test

Methods and Comparison of Results, Symposium on Fire Test

Methods, ASTM Special Technical Publication, No. 301,

1961.

[2] Z. Zabawsky, Private communication.

[3] Z. Zabawsky, Private communication.

[4] Denyes, W. and Raines, J.,, A Model Corridor for the Study

of the Flammability of Floor Coverings, Nat. Bur. Stand.

(U.S.), NBSIR 73-200 (May 1973).

[5] Denyes, W. and Quintiere, J., Experimental and Analytical

Studies of Floor Covering Flammability with a Model

Corridor, Nat. Bur. Stand. (U.S.), NBSIR 73-199 (May 1973).

37
TABLES

38
j:: VD

iH r-t 00 00

-H

w \ \ \ \

(U 00 00 ^ 00 LTl in 00 CO ^ 00 ^ rn (N

3^ .c iH ^ r-? 1 \ \ \ \ ^( u rH 1 •—1 1 r»-)" r—T

rHH 1 •—1

CJ

G) c 1 ft) I— 1—1 00 VO 00 1

oa

-rH \ r-H \ \ P-) \ iH rH e

rH

O fO fO 0

ca cn '0

>1 4J rj \N0 0\ ^ C^ LTi ^ in cTi in O vx) fsi in o ro in

00 vo ^ in CO VX) CTi in r~ 00 o

'H (J o

•H rH 1 1 c • 4-* 0 ^ ra c tjl 1 e

U'

H >-i 1 fd "H —

0 0

-- c e fa X3 M rH X C -H u rH •H O fa (C u N O ^ ID 00 VD 00 (N vo vo o in ro oo o 00 (N <N CQ (d c

Ci\J <N (N CN (N r-H ro

m

n ro rH

n roT 0 O

U oa •H 4-1 (0 r^ > rH p , , 1 4-1 OJ

'"1 (0 •H rH ir, fa

CL. 1 rr-1 fa QJ CM

P-i

<-• rH

O

u (J • -H c u c

(b (0 o w rH 1 fd c I' C r; Tt . rT-< c 1 CP 0 O 0 0) A; r-" (d i-l <U OJ 0) 0 4-J (D 4-1 4J 0.1 rH 1—( fd

r-< -J CHrH

O

v-' ' g 4-1 4-) -t-1 4-1 4J QJ 4-1 (1) <U <L) +J 4-1 (1) 4-1 (l) o in >i c

ri-t IT3

D

D

D 3 0 4-) 3 4-) 4-1 4J

O 0 4-1

D 4-1 o C

M

'H 0 ^:3 1^ 1-2 1^

u •"3

D P 3 C)

U

D »D P o rH CO U> c •H

•-3 \\ "-J l-J •d \ ""i V4

r- , r \ 1^

M > 1 +J U \, Q) (1) Q) Q) \ <D W \ ^ OJ "V t/) 1 Q) fd +J 4-1 -U 4J Ch & 4-1 CL, di CLi Cli 4-1 >1 in CO *~ o CM a CQ 3 3 3 3 0 (X a< OJ OJ CL, P rH rH U

1^ 4-1 4-1 4-1 0 Cr.

O rH o o > 3 a 04 c - O • CU

u Id 1 •rH

a, 00

Cl(

a Clj rH 1 0 0 C) j 0 0 >-l C) >i u 4-1 Cn'D

cu a,J fO di (0 O. Cl, (-1 c C 01 01 01 01

C OJ 1 0 0 0) 0 0) 0 0 o 0 dl 0 01 , ^ o o o u •H N 1 0 0 >-H M x; 0 x; x: o 0 0 x; 0 rH c rd m fd fd >-l -H

Q) iJ CP 1-5 Cr> (U CO

J Ui Ifl ^^ 01 13 1-3 t/j 1-3 -H <4H

m

O

U

o. (0 fd > > C/3 0]

M !h !h

u

O OJ

1-H x: 1—1 x: 0) e rH rH rH d) rH

g ^ i c D P E p

p rH X! fd OJ CO <D W M ,j O OJ O &^ 0) 1-1 c QJ O :!.' (/; ;n P cn C/j 01 fa X! D-i > > 1 T) > > > > T) ' '

I- OJ c p

CD 0) -H c C <D

C 0) 0) c; > (X)C <li >, rH rH rH rH r-, fd 01 ij 4-1 0) i_q 01 0 1-3 J fd >, >n >1 >ix; Id 4-1 > > "S C C C 4-1 P ! 0 o -H H •rH •H 0) 'V s s 3: i > > u i D QJ \ >-i 1 i) o in o o PC N

r~i ro in in rr, 0

^. I o o o o o X o \ in 1 ro in 1! u u u o u u i c c c i •H r4 -H •H -H -H c M i-i >H o" 1 0 0 0 rH rH -H r-H rH iH •H 0) 01 0) r- 1 1 iH C iH C iH >1 >i >i >i >i >i Uh 4J 4J ^ i 1 (11 >i O >i O >i V4 u u Sh iH l-l cu rH rH in cn c/) i 2 iH 2 .H 2 o u u U U O rH 0 0 (U (U Q-i CJ 1 4-1 •H <i <C < fiC < o O 0 1 c

fa 2 [i4 2 Cm s s rH^ rH* iH* rH 0) u u u CfP cSP (tP &P oV cAO b-i 0 O O >1

03 2 o o o o o o un h-M ^ \V iH CM ro in >^ o o o o o o U i Ti 1 1 1 1 1 i (d

r-l iH i-H r-H r-l rH 'd 1 Q (X

a ec; DC ^ 1 1 \J 1 n t OJ i I 1 Q) •a rH (N m ^a* in r-l cNj n in t-D rH rH (N r-H rsi r 

1 o 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 i u 2 2 2 2 2 < < <c < <C < o ?S [2 a, (l^ 1

39
Table 2. Flame Spread Index and Chamber Temperature Rise

Results and Comparison Between AFRP-1 and AFRP-2

IjFlooring

j Flame Spread Chamber Temp Rise°F

AFRP-1 AFRP-2 AFRP-1 AFRP-2

! 7\ ^

1 A-1 o o OZ ob "7 C/o Z 0 41

j A- z J J 1

o Q r» z y U / / O c: O Z D Z A— J Q A y 0 / 1

O "7 "3 Z / J

1 A4

83 100 74 230

A5

'

. 493 — 351

N-1 89 118 396

N-2 65 243

N-3 ^0 52 87 253

N-4 88 405

N-5 89 63 286

0—1 X 'I 0 ^47

W— 1 VV J. /- D u Z9 Z9 X1

RO 100 100 — —

r\A — X/1 /n;:) pdUr\ Z Z ZJ X D / X144 7/ J 1 J

A— 7 /r>;=)rl 1 X u JR p0 nu X 1 0 4Hoy

A-3/pad 253 229 122 282

A-4/pad 275 111

A-5/pad 682 473

N-2/pad 90 333

N-3/pad 72 72 110 311

N-4/pad 172 473

N-5/pad 97 106 120 324

0-1/pad 457 570

W-l/pad 43 46 89 255

40
Table 3. Flame Spread Ratings and Comparison

Model

Corridor

Flooring AFRP-1 AFRP-2 (MMFPA) UL-992 E-162 E-84

(Btu/min)

A-1 82 85 750 0.9 145 43

A2

331 290 750 1.2 263 50

A3

94 98 600 225

A4

83 " 100 750 1. 3 262

A5

493 300 309

N-1 70 89 600 1.1 284 237

N-2 65 1, 000 210 179

N-3 50 52 1, 000 140

N-4 88 500 1.9 173 - N-5 76 89 750 1.1 241

0-1 ~ 148 300 2.1 616 71

W-1 47 39 1,250 mm 64 50

A-l/pad 225 167 300 2. 6 150 298

A-2/pad 410 580 400 2 . 3 445 279

A-3/pad 253 229 < 300 265

A-4/pad 275 400 291 I

A-5/pad — 682 <300 - 400 -

N-2/pad 90 600 - 289 - N-3/pad 72 72 750 185

N-4/pad 172 <300 11.8 253 - N-5/pad 97 106 300 332

0-1/pad 457 <300 24 . 0 764

W-l/pad 43 46 750 119

R-1 43 1, 250 400

R-2 66 1,000

R-3 98 500

41
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43
Table 6. Flame Spread Ratings and Comparison

Model

Corridor

Flooring

Condition C

AFRP-2 (cm)

(MMFPA)

(Btu/min) UL-992 E-162 E-84

A- 1 44 750 0.9 145 43

A- 2 55 750 1.2 263 50

A- 3 48 600 225

A- 4 46 750 1.3 262 - A- 5 61 300 309

A- 6 34 1, 250

N- 1 45 600 1

.

1 284 0 0 T 237

N- 2 55 1, 000 210 179

"NT 3 .A . 1,000 — 140 - N- 4 59 500 1.9 173 -

0- 1 >100 "

. 300 2.1 616 71

W- 1 30 1,250 - 64 50

W- 2 •53. '. 1,250 - - -

P- 1 '74- 500 - - - P- 2

A 1 1 , UUU

P- 7 4 8 1,000 _

A-1 pad 3 00 2.6 150 298

A2

pad 70 . 400 2.3 445 2 79

A3

pad 93 <300 265

A4

pad 6 3 400 291

A5

pad ..;7Q <300 400

A6

pad 47 1,000 - - -

N-2 pad 86 600 - 289 - N-3 pad 35 750 185

N-4 pad >100 <300 11. 8 253

0-1 pad >100 <300 24 . 0 764

W-1 pad ^32: - 750 119

W-2 pad 55 1,250

P-1 pad >100 • <300

R- 1 10 1,250 400

R- 2 24 1, 000

R- 3 43 500

R- 4

- m - 1,250

RO 60 1, 250

44
Phase III, Part I

Table 7. Test Schedule

Chamber Temperature Panel Temperature

H y yj V— J D \J

1 — ^ A A o X — J.'l'i A-2, A-5

N-3, W-1,

R-3

A-2, A-5

N-3, W-1,

R-3

A-2, A-5

N-3, W-1,

R-3

A-2, A-5

N-3, W-1,

R-3

3 - 197°C A-2, A-5

N-3, W-1,

R-3

A-2, A-5

N-3, W-1,

R-3

A-2, A-5

N-3, W-1,

R-l

4 - 227°C A-2, A-5,

N-3, W-1,

R-3

45
- Table 8. Flame Spread Results

h m "K" Sample Temperature Panel Temperature

490°C 550°C 670''C

1 - 144°C 55 65

A-2 2 - 172°C 57 63

3 - 19 7°C 59 73 92

4 - 227°C >100

1 - 144°C 61 69

A5

2 - 172°C 74 73

3 - 197°C 68 80 97

4 - 22/ C >100

1 - 144°C 4 22

N-3 2 - 172°C 18 24

, 3 - 197°C 16 30 35

4 - 2 2 7 ° r 51

1 - 144°C 30 37

W-1 2 - 172°C 37 41

3 - 197°C 35 43 36

4 - 22 7°C 39

1 - 144°C 43 51

R-3 2 - 172°C 52 58

3 - 197°C 47 56 75

4 - 227°C 98

46
Table 9. Humidity and Wear Tests

Humidity Tests

Conditioning RH

Samples

Moisture Content %

30% 50% 65%

Results in cm

30% 50% 65%

30 30 29

5 4 4

61 61 59

30 34 31

26 24 26

W-1 6.0 6.5 9.7

N-3 . 1.9 2.2 3.3

A5

1.0 1.2 1.7

A-6 0.9 1.0 1.1

R-2 1.4 1.4 1.4

o . ^ r, ^ ^ Wt Moisture x 100

% Moisture Content = Wt Bone Dry Sample

Results - Flame Spread Distance

Wear Tests

Results

Samples Normal Dirty

N-3 4 5

A-4 46 46

A-6 61 69

47
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48
ILLUSTRATIONS

49
ROOM FIRE SITUATION

Figure 1. Room Fire Situation

5G
ORIGINAL APPARATUS

Figure 2. Original Apparatus.

51
ORIGINAL APPARATUS ENCLOSED

Figure 3. Original Apparatus Enclosed.

52

54


INDIVIDUAL TEST COMPARISON

32

28

24

20

16

12

8

AFR P-2 FLA ME FRPI

LO CATI ON

DISl ANC

(C M)

AFRF FlAI F RON T

LO CATI ON

//

/

/

/ /

. -

/ \ AFRP-2 :hamber

A IR T EMP

1- AFR! :;han IBER

Al R T EMP

Tl ME (MIN

750

700

650

600

550

TEMP

op

500

450

40O

2 3 4 5 6 7 8 9 10 II 12. 13 14 6.

Figure 8. Phase I — Individual Test Comparison — AFRP-1

AFRP-2.

57
GRAPHICAL COMPARISON AFRP-2 VS. AFRP-1 AND OTHER TESTS

O LEAST SQUARES FIT FOR ALL AFRP-2 POINTS LESS THAN 100 + LEAST SQUARES FIT, ALL POINTS (CORRELATION COEFFICIENT , r)

700 o

p 600 <Q 500 <

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a:

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ijj

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- +

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yr=0.29

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100 200 300 400 500 600 AFRP-2 FLAME SPREAD RATING

100 200 300 400 500 600 AFRP-2 FLAME SPREAD RATING

500

400 - <

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<

LlI tr

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20O

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t52

100 200 300 ^ 500 600 AFRP-2 FLAME SPREAD RATING

100 200 300 400 500 600 AFRP-2 FLAME SPREAD RATING

Figure 9. Phase I — Graphical Comparison AFRP-2 Vs

AFRP-1 and other tests.

58
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61

THERMOCOUPLE PLACEMENT IN CHAMBER WALLS

+ +

9) 10

CEILING

END WALL

+

7

+

8

Figure 14. Phase III - Walls.

- Thermocouple Placement in Chamber

63
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68
STUDY OF AIR PATTERNS

SMOKE PATTERNS - NO BURNING SAMPLE

2» SIDE VIEW

\V,

Burner ^^^^ 0\

1 90 CM

25 SEC

8 SEC

TOP VIEW

Figure 20. Phase III Part 3 — Study of Air Patterns Arrows

Indicate Flow Directions.

69
STUDY OF AIR PAHERNS

AIR VELOCITY MEASUREMENTS

m

K 1 X

456

XXX

1 2 3

LOCATION OF

^HOOD DUCT

TEST

191

^^^T

^' OPEN

1 2 3

FPM

425 380 280

4 5 6

490 600 650

7

400

8 9 AVE

200 155 400

DUCT

192 PART

CLOSED

FPM

330 270 250

- 450 450 55P 370 200 230 350

RESULTS FLAME SPREAD MAX. TEMP. MAX. SMOKE

191

192

58

63

204 °C

204 °C

.20

.24

DURING TEST 191

TIME -1:00 +0:48 +2:18 +4:30 8:00

VELOCITY FPM

(X5) 450 600 700 600 600

Figure 21. Phase III Part 3 — Study of Air Patterns Air

Velocity Measurements.

70
toO

CL<oz5z<

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UJ

CO

— CO ^ UL. I>U

<\) 0} o

to CM Cn U

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71
72
HEAT FLUX METERS - TEST 187

0.8 I

1 1 1 1 1 1 1 1 1 1 1 T

DATA LOST

FF-30 CM

Figure 24. Phase IV - - Heat Flux Meters -

73

- Test 187
74
NBS-1 14A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

'IULK A 1 UK Ki;i'()|M- NC). NBSIR 74-4952. Ciov't Acc'cs.sion No.

3. Klc ipienl '.s Acccs.sion No.

4. 1 1 1 LI-: AND m

Development of a Radiant Panel Test for Flooring Material

5. Publication Date May 1974

6. Performing Organization Coje

7. AUTHOR(S)

L. G. Hartzell, Research Associate

8. Performing Organ. Report

NBSIR 74-495

9. PERFORMINCi ORGANIZATION NAMl- AND ADi:iRi:SS NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project / I ask \^'orl< Unit .\o. 490-6570

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

^ame as no. 9

13. Type of Report &; Period Covered / \ (one year)

Final- 1972-1973

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

Revised version of NBSIR 74-427 issued March 1974

16. ABSTRACT (A 200-word or less factual sutnmary of most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.) This paper summarizes the work of a year' long program to continue the development

of a radiant panel type test for flooring materials, the original concept of which was developed at the Armstrong Cork Company's Research and Development Center in Lancaster,

Pennsylvania. This program at the National Bureau of Standards had as its goal, the

further development of the test for possible adoption as a standard ASTM test method.

The program work was divided into five phases. During the first phase, an attempt

was made to duplicate the performance of the original apparatus in a similar one at the

National Bureau of Standards Laboratory. The proof of this duplication was sho^Nm in

replicate testing using a wide range of flooring on both apparati.

In the second phase of the program, a new set of test conditions were found in an attempt to eliminate some of the more serious equipment and procedural problems of the

test. These new conditions provided the test with the ability to rate flooring

materials according to their ability to resist the surface spread flames.

Under the third and fourth phases of the program, the effects of changes in some test parameters was investigated and other test characteristics were measured. Phase

V, the data analysis and report, concluded the program.

17. KEY FIORDS (six to twelve entries: alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Carpet; fire test; f lammaijility; flooring; heat flux; ignition; radiant panel.

18. AVAILABILITY Unlimited

I For Official Dis tribution. Do Not Release to NTIS

er From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CM

[ Order From National Technical Information Service (NTIS)

Springfield, Virginia iZl'SI

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

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UNCLASSIFIED

21. NO. OF PAGES

78

22. Price

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