NBSIR 75-782

Full-Scale Corridor Fire

Experiment Using A Glass Fiber

Carpet

Leslie H. Breden

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

December 1975

Final

U S, DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 75-782

FULL-SCALE CORRIDOR FIRE

EXPERIMENT USING A GLASS FIBER

CARPET

Leslie H. Breden

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

December 1975

Final

U.S. DEPARTMENT OF COWilERCE, Rogers C.B. Morton, Secratary

James A. Baker, III. Unthr Sacratary

Dr. Betty Ancker-John»on, Assistant Sacratary for Sciatica and Jachnology

NATIONAL BUREAU OF STANDARDS, E.-nest Ambler, Acting Diractor

CONTENTS

Page

LIST OF FIGURES iv

SI CONVERSION UNITS v

1. INTRODUCTION 1

2. EXPERIMENTAL DESIGN 2

2.1. Description of the Corridor 2

2.2. Description of the Burn-Room 2 2.3. Description of Wood Cribs 2 2.4. Description of the Instrumentation 3

2.5. Description of the Carpet 3

3. PROCEDURE 3

4. OBSERVATIONS AND RESULTS 4

5. CONCLUSIONS 4

6. REFERENCES 5

iii
LIST OF FIGURES

Page

Figure 1. Corridor Facility 7

Figure 2. Corridor Wall Sensor Locations , 8

Figure 3. Corridor Floor Sensor Locations 9

Figure 4. Burning Mode In Corridor 10

Figure 5. View In Burn-Room Showing Wood Cribs.

Center Crib on Load Cell. Thermocouples and

Pitot Tubes in Doorway 11

Figure 6. Weight Loss Versus Time 12

Figure 7. Rate of Weight Loss Derived from Load Cell Data. . . 13

Figure 8. Celling Temperature of Burn-Room 14

Figure 9. Celling Temperature 1 ft from Centerline of

Doorway 15

Figure 10. CO and CO2 at 20 ft and 6 ft High Height 16

Figure lOA. O2 at the Burn-Room Door 17

Figure 11. Heat Flux from Burn-Room 18

Figure 12. Radiation on the Floor 1-1/2 ft from West Wall ... 19

Figure 13. Temperature Across Floor at 6 ft 20

Figure 14. Temperature Profile at 5 ft 21

Figure 15. Heat Flux Meter 22

Figure 16. Temperature Down Corridor Floor 23

Figure 17. Ceiling Temperature Down Corridor 24

Figure 18. Temperature Profile at 25 ft 25

Figure 19. Velocity at Top Exit of Window 1 ft 26

Figure 20. Temperature Profile at Exit Window 27

iv
SI CONVERSION UNITS

In view of present accepted practice in this technological area,

U.S. customary units of measurement have been used throughout this report.

It should be noted that the U.S. is a signatory to the General Conference

on Weights and Measures which gave official status to the metric SI system

of units in 1960, Readers interested in making use of the coherent

system of SI units will find conversion factors in ASTM Standard Metric

Practice Guide, ASTM Designation E 380-72 (available from American

Society for Testing and Materials, 1916 Race Street, Philadelphia,

Pennsylvania 19103) . Conversion factors for units used in this paper

are

Length

1 in

1 ft

= 0.0254^ meter

= 0.3048 meter

Area

1 in^ = 6.4516* x 10 meter^

1 ft^ = 9.2903 X 10" meter^

Mass

1 lb = 0.4536 kg

Energy

1 Btu = 1054 J

Temperature

°C = 5/9 (Temperature °F - 32)*

Power

1 Btu/min = 17.57 W

Time

1 min = 60 s

*Exact value

V
"0 » [
FULL-SCALE CORRIDOR FIRE EXPERIMENT

USING A GLASS FIBER CARPET

Leslie H. Breden

A corridor fire experiment was carried out using a glass

fiber carpet. It was observed that with a fuel loading of 2.7

pounds per square foot of wood in an adjacent fire room, no propagation of the fire occurred down the corridor. The glass

fiber carpet in the burn-room became discolored and there was

a significant weight loss of the carpet directly in contact with

the fire. The carpet did not produce significant levels of

smoke and did not spread the fire into the corridor.

Key words: Carpet; corridor test; fire testing; f lammability

;

glass fiber.

The current mandatory carpet f lammability standard, DOC FF 1-70, uses

the methenamine pill test to keep easily ignited carpets from the market.

In some cases, however, such as in institutional buildings, multiple

occupancy buildings, and other special occupancies, a more severe test of

carpet performance is desirable. In the course of developing such a test,

it has been found that an important parameter is the performance of the

carpet in propagating fire down a corridor [1]-^. In addition, it is of

interest to determine, where possible, the relative contributions of fiber,

latex binder and backing to flame spread of the assembled carpet. This

is most readily done when one or more components of the carpet is of a low order of combustibility. One potential candidate for this study is

carpeting constructed of glass fiber.

The purpose of this paper is to report the effect of glass fiber

carpet on the spread of fire on carpet in a corridor when the fire originates in a room adjacent to the corridor. The results are expected to be

useful on two counts: 1) they provide at least one illustration of how^ a "high performance" material behaves in a full-scale fire test; and

2) they provide an indication of the contribution to flame spread of the

backing and latex components of the assembled carpet. (The corridor

investigation described below uses an experimental configuration to

investigate fire spread over a flooring system and is not a test method

to evaluate carpets.)

Numbers in brackets correspond with the literature references listed at

the end of this paper.

1. INTRODUCTION

1
2. EXPERIMENTAL DESIGN

2.1. Description of the Corridor

Schematic drawings of the NBS corridor facility are shown in figures

1, 2 and 3. The corridor has been described extensively by other workers

[1,2].

The corridor is 30 feet long, 3 feet wide, and 8 feet high. At one

end of the corridor there is a doorway connecting to a burn-room where a crib fire is initiated. The walls and the ceiling are constructed of

1/2-inch low density cement-asbestos board on steel studs covered by 5/8-

inch gypsum wall board. The subflooring consists of 1/4- inch high density

cement-asbestos board on a brick base. An exit window, 70 x 41 inches,

is located at the far end of the corridor. Part of the air needed for

combustion of the cribs enters the burn-room through the vents in the

outer walls while additional air enters the burn-room through the door

from the corridor. Air enters the corridor along the floor and then into

the burn-room. The hot combustion products from the burn-room flow out

along the corridor ceiling and finally out the top of the exit window as shown in figure 4. , ,

; ; sjvf.. ; -/.i r;

2.2. Description of the Burn-Room

A schematic drawing of the burn-room is shown in figure 1. The

burn-room is of concrete block construction, approximately 7.8 x 8.3 x

9.2 ft high, with a door opening of 6.5 x 2.5 ft. Located one ft above

the floor of the burn-room are two small vents, 7 x 14 inches. These

vents are open to the atmosphere and are meant to simulate air ducts.

The burn-room interior is sprayed with a one-inch thick protective

coating of refractory material over the concrete block. This coating has

the following properties: ;

. *

,

Density 18.5 Ib/ft^

Thermal conductivity 0.057 Btu/hr °F

Specific heat „, 0.2 Btu/lb °F

C Thermal diffusivity i 0.015 ft^/hr

2.3. Description of Wood Cribs

Full-scale experimental fires for room simulation suggest that wood

cribs present a realistic fire severity [3]. Four hemlock wood cribs are used to simulate burning objects in a room. The cribs are made of sticks

1-1/2 inches wide with a cross stick spacing of 3 inches (see fig. 5).

There are 4 sticks in each layer with 18 layers except for the top and

bottom layer which has 2 sticks. The 4 cribs are oven dried to a moisture content of approximately 10%. They are placed in the burn-room on

a load cell platform; each crib weights approximately 42.5 lbs with a total weight of 170 lbs. The four cribs yielded a fuel loading of 2.7 lbs

2
per square foot of floor area and maxlmxun burn rate of 2.5 lbs of wood

per minute. To initiate the experiment they are ignited by 250 g of

heptane placed in a pan under each crib. Assuming a value of 5,000 Btu/lb

for 120 lbs of wood due to incomplete combustion, the heat release rate

peaks out at 60,000 Btu/min and maintains this rate for 8 to 9 minutes

reflected in the weight loss curve in figure 6.

2.4. Description of the Instrumentation

Table 1 outlines the measurements taken in the burn-room and the

corridor. Chromel-alumel type thermocouples are used to measure temperature. Pitot-static tubes at the top of the burn-room and exit doors

measured the combustion product velocities while the bottom pitot-static

tubes measured the inlet airflow. Radiometers are mounted in the floor

of the corridor to monitor the incident flux. In addition, there is a radiometer mounted on the wall monitoring radiation in the burn-room.

Heat flux meters are also used to measure heat loss through the walls.

Finally, the cribs are placed on a load cell platform so that the burning

rate of the wood cribs can be measured. All measurements are recorded

by a high speed digital data acquisition system. This system records

all imputs at 20 second intervals with seven recording points per second.

2.5. Description of the Carpet

The carpet used in this experiment is composed of glass fiber with a total weight of 70 oz/yd^. The face fiber has a weight of 50 oz/yd^ and

a back fabric weight of 7 oz/yd^. There is also a latex binder of

13 oz/yd^. The carpet was supplied by Carolina Narrow Fabrics of WinstonSalem, North Carolina.

3 . PROCEDURE

A blank run (test No. 355), was made with four cribs in the burnroom, and a cement-asbestos board floor in the corridor. A metal can,

filled with 250 g of heptane, was used to ignite each crib. Measurements

were taken with these burning cribs alone. This procedure was then

repeated with the glass fiber carpet in the corridor over the cementasbestos board (test No. 366). The glass fiber carpet was laid down

with no pad and consisted of two four-foot wide pieces spliced with the

seam parallel to the length of the corridor. In addition, a piece of

glass fiber carpet, two ft by four ft, was extended into the burn-room

under the cribs. This piece provided for a continuous path for the

flame to spread into the corridor.

3
4. OBSERVATIONS AND RESULTS

After ignition, the cribs burned vigorously and reached a maximum

rate of weight loss after 3 minutes. This constant rate of weight loss was maintained for 8 to 9 minutes after which the crib fire began to

decrease as illustrated in figure 7. A comparison of the burning rate

of the cribs between the blank and the glass fiber carpet, indicated no significant differences. Fung, et al. , have shown that with refractory

material as the burn-room coating, it appears that the heat loss of the

cribs to the burn-room surface by conduction is only significant during

the early phase of burning [2]. For the rest of the test, the heat loss

by conduction is about 15% of the total heat release. The radiant energy

contribution to the energy supply to the corridor is about 10% of the

total energy transport into the corridor. This is because the corridor

is exposed only to the burn-room fire through the doorway. Thus, the

bulk of energy released to the corridor from the cribs is in the form of

convective energy by way of the burn-room doorway.

The ceiling temperature in the burn-room, as shown in figure 8, was

not significantly different from the blank. A potential heat measurement

made on the carpets yielded 1,165 Btu/lb. There was about a 16% weight

loss of the carpet that was directly in contact with the burning cribs.

During the period of maximum burning, the fire plume extended from

the burn-room and licked the corridor ceiling near the burn-room providing

a temperature profile shown in figure 9. Figures 10 and lOA illustrate

the gas concentrations, produced by the wood alone during the blank test,

taken 20 feet down the corridor and 2 feet from the ceiling. A gas

analysis was not carried out during the carpet test. Smoke and gaseous

products passed into the corridor and generally filled the upper part of

the corridor. The radiation at the burn-room door is shown in figure 11.

It should be noted that the radiation and heat flux level on the

floor was high enough to cause flame propagation down the corridor had

the carpet been made of an organic material (figure 12) [4]. Figures 13

through 20 summarize the temperature and air velocity measurements which

were observed in the corridor and at the exit window. Differences that

exist as shown in figure 14 can be attributed to the insulating effect of

carpet. Figures 14 and 18 illustrate the measured temperature profile in

the corridor due to the glass fiber carpet at the 5 feet and 25 feet

positions

.

5. CONCLUSIONS

The glass fiber carpet contributed to the fuel load in the burn-room

and increased the temperature in the corridor. There was no propagation

of the fire out of the burn-room with a 2.7 pound per square foot wood

fuel loading. The carpet in contact with the burning cribs became discolored and showed a significant weight loss. While combustible materials

were used in the carpet as binders and dyestuffs, there was no significant

spread of the fire into the corridor.
6. REFERENCES

[1] Huggett, C, Carpet Flammability and the NBS Corridor Fire Program,

ASTM Standardization News, Vol. 16, 1 (1973).

[2] Fung, T. C. W., Suchomel, M. R. and Oglesby, P. L. , The NBS Program

on Corridor Fires, Fire Journal, Vol. 67, 41 (1973).

[3] Christian, W. J. and Waterman, T. E. , Fire Behavior of Interior Finish

Material, Fire Technology, (Aug. 1970).

[4] Quintiere, J., Some Observations on Building Corridor Fire, Presented

at the 15th International Symposium on Combustion in Tokyo, Japan,

held August 25-31, 1974.

USCOMM-NBS DC

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Figure 5. View in Burn-Room Door Showing Wood Cribs.

Center Crib on Load Cell. Thermocouples and Pitot

Tubes in Doorway.

11
0 300 600 900 1200 1500

TIME IN SECONDS

b 300 600 900 1200 1500

TIME IN SECONDS

Figure 6. Weight Loss Versus Time

12
O 366 TEST

A 355 "

0 4 8 [2 16 20

TIME, min

Figure 7. Rate of Weight Loss Derived From Load Cell Data.

13
Figure 8. Ceiling Temperature of Burn-Room.

.14
1500

300 600 900 1200

TIME IN SECONDS

1500

1500

1200

ooUJ

(T

<

LJ

Q.

UJI900 —

600 —

300 —

300 600

ME IN 900

SECONDS

1200 1500

Figure 9. Ceiling Temperature 1 ft from Centerline of Doorway.

15
Figure 10. CO and CO2 at 20 Feet and 6 Feet High Height

16
250 500 750

TIME IN SECONDS

1000

Figure lOA. 0^ at the Burn-Room Door

17
0 300 600 900 1200 1500

TIME IN SECONDS

TIME IN SECONDS

Figure 11. Heat Flux from Burn-Room.

18
Figure 12. Radiation on the Floor 1-1/2 ft From West Wall.

19
1 ft

2 ft

3 ft

6 ft

0 300 600 900 1200 1500

TIME IN SECONDS

300 600 900 1200 1500

TIME IN SECONDS

Figure 13. Temperature Across Floor at 6 ft.

20
0 300 600 900 1200 1500

TIME IN SECONDS

0 300 600 900 1200 1500

TIME IN SECONDS

Figure 14. Temperature Profile at 5 ft.

21
Figure 15. Heat Flux Meter

22
Figure 16. Temperature Down Corridor Floor,

23
Figure 17. Ceiling Temperature Down Corridor.

24
500

400

o

p

iij g 300

5

(T.

I200

100

500

TEST 355

from ceiling

0 300 600 900

TIME IN SECONDS

200 1500

300 600 900

TIME IN SECONDS

200 1500

Figure 18. Temperature Profile at 25 ft.

25
0 300 600 900 1200 1500

TIME IN SECONDS

2

1500 I.I 1

1

1200

/'^''^\''...11J^'^'^' test 366

900

600

300

0 ! 1 1 1 0 300 600 900 1200 15

TIME IN SECONDS

Figure 19. Velocity at Top Exit of Window 1 ft.

26
Figure 20. Temperature Profile at Exit Window

27
NBS.n4A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 75-782

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLF-: AND SUBTITLE

Full-Scale Corridor Fire Experiment Using a Glass Fiber Carpet

5. Publication Date December 1975

6. Performing Organization Code

7. AUTHOR(S)

Leslie H. Breden

8. Performing Organ. Report No. IR 75-782

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE V

WASHINGTON, D.C. 20234 \

10. Project/Task/Work Unit No. 4927677

11/" ^ / ^ KT

1 1. Contract/Grant No.

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

same as No. 9

13. Type of Report & Period

Covered

Final RpDnrl"

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

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

bibliography or literature survey, mention it here.)

A corridor fire experiment was carried out using a glass fiber carpet.

It was observed that with a fuel loading of 2.7 pounds per square foot of

wood in an adjacent fire room, no propagation of the fire occurred down

the corridor. The glass fiber carpet in the burn—room became discolored

and there was a significant weight loss of the carpet directly in contact

with the fire. The carpet did not produce significant levels of smoke

and did not spread the fire into the corridor.

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

)

Carpet; corridor test; fire testing; f lammability ; glass fiber.

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