NBSIR 74-456

Evaluation of the Fire Performance of

a Dibromotetrafluoroethane - Blown

Rigid Polyurethane Foam

T. G. Lee, W. J. Parker and M. Tryon

Fire Technology Division

Institute for Appliea Technology

National Bureau of Standards

Washington, D. C. 20234

April 1974

Final Report

Principal Sponsor

Naval Ship Research and Development Center

Carderock, Maryland 20034

NBSIR 74-456

EVALUATION OF THE FIRE PERFORMANCE OF

A DIBROMOTETRAFLUOROETHANE - BLOWN

RIGID POLYURETHANE FOAM

T. G. Lee, W. J. Parker and M. Tryon

Fire Technology Division

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

April 1974

Final Report

Principal Sponsor

Naval Ship Research and Development Center

Carderock, Maryland 20034

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

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

COMTENTS

Page

1. INTRODUCTION 1

2 . MATERIALS 2

3. SPECIMEN PREPARATION 2

4. TEST METHODS AND PROCEDURES 2

A.l Surface Flammability (ASTM E 162) 2

4.2 Smoke and Combustion Products 3

4.3 Fluorocarbon Content of Foam Specimen 4

^•4 Ignition Temperature 4

4.5 Ease of Ignition 5

4.6 Heat Release Rate 5

4.7 Fire Growth 5

5. TEST RESULTS 6

5.1 Surface Flammability 6

5.2 Smoke and Combustion Products 7 5.3 Loss of Dibromotetraf luoroethane Blowing Agent... 9

5.4 Flash-Ignition Temperature 10

5.5 Ease of Ignition 10

5.6 Heat Release Rate.. * 10

5 . 7 Fire Growth Experiments , , , , 11

6 . SUMMARY ' 12

7. ACKNOWLEDGEMENT 13

8 . REFERENCES 13

i

EVALUATION OF THE ^IRF PERFOPMANCE OF A

DIBROMOTETRAFLUOROETHANE - BLOWN RIGID POLYURETHANE FOAM

T. G. Lee, W. J. Parker and M. Tryon

The fire performance characteristics of a dlbromotetrafluoroethane - blown rigid polyurethane foam were Treasured by several

laboratory test methods. Measurements included: surface flammabilitv, smoke and gases generated at elevated temperature

and during combustion, ignition temperature, rate of heat

release, and fire growth. The maximum concentration of the

blowing agent in the specimen was approximately 13 Wt%.

Specimen density was 0.046 g/cm-^. As a function of temperature,

release of Allowing agent from collapsed cells began at about

60°C and became considerable at 135°C. The material had a flame

spread index (ASTM E-162) of 11 with smoke levels of 170 and 480

(maxim.um specific optical density) under non-flaming and flaming

exposures, respectively. The measured rate of heat release was

8.8 W/cm^, about 5 times that of a fibrous glass Insulation.

The measured flash Ignition temperature was 530°C for the

material.

Key words: Dlbromotetrafluoroe thane: flame spread index; fire

tests: heat r«=lease rate; ignition temperature: rigid urethane

foam; smoke.

1 . INTRODUCTION

In the evaluation of the fire performance of structural rigid

polyurethane foam material which may be directly exposed to potential

shipboard fires, consideration should be given to the following

characteristics

Surface Flammability

Smoke and Toxic Products Generated During Combustion

Release of Fluorocarbon Blowing Agent Relative to Temperature

Ignition Temperature

Ease of Ignition

Rate of Heat Release

Fire Growth Potential

While it is not possible to relate any of these characteristics

directly and quantitatively to a life hazard under all use conditions,

test methods now exist or can be adapted for comparative evaluation

of these properties. Smoke generation, surface flammability, rate of heat

release, and ignition temperature can be determined with relative ease using small-scale specimens and recognized standardized test methods.

Another potential hazard not directly related to fire is the possible

decomposition of the foam at temperatures slightly above ambient and the

release of Mowine agent which is an integral part of the foam system.

1
Because the agent used in this foam Is considered toxic* at some con- centrations and since the fire properties of the foam are dependent

in part on the blowing agent, information on its rate of release at

elevated temperature was also obtained. This study was sponsored by the

Naval Ship Research and Development Center, Carderock, ^laryland.

2 . MATERIALS

The closed cell rigid polyurethane foam was polymerized from resin

and blowing agent by the sponsor into crude slab sections roughly 1.3

by 1.3 m with a thickness of 20 cm. The blowing agent, which is trapped

in the closed cell structure of the foam, was a fluorocarbon compound,

1,2 - dibrotnotetrafluoroethane (fluorocarbon 114B2 or Halon 2402),

an excellent fire retardant agent. Although the exterior surfaces varied

considerably, the interior of the large specimen was fairly uniform in

density with typical cell diameter of about 1 mm. The measured bulk

densitv, based on an average of five samnles, was 0.046 g/cm^ (2.9 Ib/ft^)

A second specimen, labeled "aged" and fabricated on October 5, 1971

by the sponsor, appeared to have somewhat smaller cell diameter but a similar density of 0.046 g/cm^ (2.9 Ib/ft^).

, 3. SPECIMEN PREPARATION

Specimiens of uniform density were selected, cut into the appropriate

sizes, and then heated in an oven at 60°C (140°F) at ambient pressure for

24 hours. This was followed by conditioning to equilibrium with an atmosphere maintained at 23°C (73"?) and 50% relative humidity. This

heating and conditioning procedure was used with all the specimens for

the surface f lammability , smoke and ignition temperature tests. For

other tests, specimens were tested as received or after conditioning by

other methods to be described.

4. TEST METHODS AND PROCEDURES

; 4.1 Surface Flammability (ASTM E 162)

Flame spread was measured using the radiant panel apparatus (ASTM

E 162) [1]**. In this test, a' specimen 45.7 by 15 by 2.5 cm (18 by 6 by

1 in) thick was mounted in a holder and placed lengthwise at an angle

of 30° with respect to the vertically mounted radiant panel. The

distance between the specimen and the panel was least at the top of the

specimen, about 12 cm (4 3/4 in). The energy output of the panel

*Freon Product Information B-2, E. I. du Pont de Nemours & Co., Wilmington

Deleware, 1969. Threshold Limit Value is 1000 ppm, LC 50 = 5%. More

recent information show that concentration above 1000 ppm is considered

unsafe for human exposure due to possible cardiac arrhythemias

**Fieures in brackets indicate the literature references at the end of

this paper

2
was controlled so that it was equal to the output of a blackbody of the same dimensions operating at 670''C.

An acetylene pilot flame was applied near the top of the specimen

and the times for the flame front to travel in three inch increments (t3,

tg, tg, ti2i ^15) were recorded. In all cases the test ended when the

flame front traversed the whole length of the specimen, or after 15 minutes

exposure time, whichever was shorter. The temperature rise was measured

by thermocouples placed in the stack above the specimen.

The flame spread index, Ig, is calculated using the equation Ig = FsQ»

where 0 is the heat evolved and Fg is the flame spread factor:

= 1 + l/(t^ - t3) + l/(tg - t^) + l/t^2 " ^9^ + ^/^15 " ^12^- '^^^ heat evolved is proportional to the observed maximum temperature rise of

the stack thermocouples.

4.2 Smoke and Combustion Products

Tests were conducted using the Smoke Density Chamber as described in

Appendix II, NBS Technical Note 708 [2]. The smoke produced during the

burning of test specimens was measured nhotometrically , employing a laboratory test method developed for the purpose. The test utilizes a closed chamber of 0.5 m^ (18 ft^) volume containing an electrically heated

furnace which provides an irradiance of 2.5 W/cm^ on the surface of a nominal 7.6 cm (3 in) square specimen. The method assumes the appli- ^ cability of Bouguer's law to the attenuation of light by smoke. Smoke

quantity is therefore reported in terms of optical density rather than

light absorbance. Optical density is the single measurement most characteristic of a "quantity of smoke" with regard to visual obscuration.

To take into account the optical path length, L, the volume, V, and

the specimen surface area producing smoke, A, a specific optical density

is defined as Dg = V/LA (log^Q 100/T) , where T is the percent light transmittance. Thus, for a selected exposure in the test chamber, and within

certain limitations, a single test permits rough extrapolation to other

surface areas and chamber volumes

Specimens are subjected to two modes of exposure conditions, namely

flaming and non-flaming. Both conditions can be considered typical in

a real fire situation. Under the non-flaming exposure mode, the specimen

receives an average irradiance of 2.5 W/cm^ on its exposed surface to cause pyrolysis and emission of smoke. Under the flaming mode, in

addition to the same surface irradiance, the specimen is subjected to

pilot flames consisting of 6 small (9.5 mm length) premixed air-propane

flamelets impinging on the base of the specimen.

Indications of the (maximum) concentrations of potentially toxic

combustion products HBr , HCN, CO, HF, and NOx were obtained by using com- mercial colorimetric detector tubes and the techniques described by

Gross, et. al. [3]. This reference provides background on the use and

limitations of the smoke and combustion products measurement methods.

3
4.3 Fluorocarbon Content of Foam Specimen

The weight concentration of fluorocarbon blowing agent, dibromotetraf luoroethane, in the foam system was measured for ^various specimens.

These included the "aged" specimen, and new specimens subjected to

selected preheating levels . An approximate rate of blowing agent loss

from the specimen at 100°C was also determined.

The general procedure used for fluorocarbon analysis was gas chromatography of gaseous samples taken from a closed container in which the

sample had been decomposed thermally. Initial evacuation of the container

was necessary to prevent excessive pressure buildup during the pyrolysis

of the foam. After sample pyrolysis in the container, a valved syringe

was used to transfer a small volume of the vapor products to a gas chromatograph for analysis. The gas chromatograph was equipped with a thermal

conductivity detector and a Porapak Q column held at 170°C. The response was calibrated by injecting known weights of the fluorocarbon and determining peak heights. A plot of peak height versus weight of sample

served as a calibration curve.

The required samples were about 24 mm in diameter and 33 mm in length.

Each sample was weighed and placed in the 100 ml volume quartz container.

A mechanical pump connected to a syringe needle in the septum of the

container, was used to evacuate the container for 30 minutes prior to

heating. The sample was decomposed by heating with a burner flame until

the foam collapsed and dense fumes filled the vessel. The container was

cooled to room temperature and samples were analyzed in duplicate. Thus

data were based on the average of two specimens, each using the above

procedures.

The rate experim.ents were conducted in a similar manner except for

the pyrolysis step. Larger samples were used and the containers held in

an oven for various periods of time at a temperature of 100°C. Vapor

samples were taken at the beginning and at various times. The rates were

determined from the initial slopes of the time-concentration curves.

4.4 Ignition Temperature

The flash-ignition temperature of the foam was determined by using

the test procedure of ASTM D 1929-68 [4]. Flash-ignition is defined as

the lowest initial temperature of air passing around the specimen at

which a sufficient amount of combustible gas is evolved to be ignited by

a small external pilot flame.

The apparatus consists of a hot-air ignition furnace with a vertical

ceramic furnace tube having an inside diameter of about 75 mm. A

specimen weighing 3+0.5 g is placed in a specimen pan located at the

center of the furnace tube. The supply of air from the bottom of the

tube passing the specimen is maintained at a velocity of either 1.5 m

(5 ft)/min or 3 m (10 ft)/min and at the prevailing temperature of the

furnace.

4
A small pilot flame located at the top of the furnace serves to

Ignite the combustible products from the specimen. After the specimen

is in place, the temperature in the furnace tube is increased at a rate

of about 60°C/min.

Temperature rise is continuously measured by a thermocouple placed

at the center of the specimen. The temperature at which flaming ignition

occurs, is reported as the flash ignition temperature.

A. 5 Ease of Ignition

The ease of ignition test [5] utilizes a pair of 2.5 cm (1 in) thick

specimens 14 by 15 cm (5-1/2 by 6 in) facing each other and separated

by a distance of 2.2 cm (7/8 in). A flat-shaped premixed-flame, somewhat

larger in size than the specimen and located in the space between the two

specimens, provides flame contact corresponding to a heat flux of 3 W/cm^.

The time to sustained ignition, i.e. the exposure time required to produce

sustained flaming, is found by a trial and error method. The specimen is

exposed for a predetermined period of time and the presence or absence of

flaming is noted. The presence of flame at any point on the specimen one minute after the exposure flame has been removed constitutes sustained

ignition. The exposure time is then increased or decreased appropriately

until the ignition time is bracketed.

4.6 Heat Release Rate

In the heat release rate calorimeter [6], the front surface of a 2.5 cm (1 in) thick vertical specimen 11.4 by 15 cm (4-1/2 by 6 in) is

exposed to thermal radiation at a 3.3 or 6 W/cm^ level from three gasfired radiant panels situated at the front and both sides of the specimen.

The edges of the specimen are shielded and the rear surface is separated

from a water cooled brass block by an air space. The brass block constitutes a small section of the wall behind the one represented by the

specimen. The heat removed from the rear surface of the specimen is

measured by the rate of temperature rise in the cooling water. A propane

burner near the flue of the calorimeter produces heat at a considerably

greater rate than that of the burning specimen. When the specimen is

burning, the propane flow is automatically reduced by the amount necessary

to maintain the flue gas temperature constant. The rate of heat release

through the front surface of the specimen is determined from the

reduction in propane flow. Onlv heat released at the front surface is

quoted in this report.

4.7 Fire Growth

Specimens of the test foam, 2.5 and 5 cm in thickness and 76 cm. (30 in) square, were tested in the ceiling location of a rectangular

enclosure. This enclosure has a 76 cm square base and height of 81 cm. It represents a small model of a compartment, in which the appropriate

heat and mass flow rates from full-scale compartment fires have been

scaled. This evaluation test is still under development and no published

references are available at present.

5
Natural gas supplied to a diffusion-flame burner in the compartment

was released through a 10 cm square horizontal porous plate located at the

left corner of the compartment opposite the opening. The air for the

burner as well as for the combustible ceiling was supplied by natural

convection through the 18 cm wide and 69 cm high opening at the front of

the compartment. The surface of the burner was positioned at 7,6 cm above

the floor in the first test with a gas flow rate of 15.1 1/min, and 28 cm above the floor in the second test with a gas flow rate of 8.5 1/min.

The radiant flux near the floor, the air temperature just below the

ceiling and the oxygen concentration of the air leaving the doorway

were measured and compared with the same measurements for other ceiling

materials.

5. TEST RESULTS

5.1 Surface Flammability

A total of 4 specimens was tested for flame spread. Two specimens

were heated according to the standard procedures at 60°C prior to the

test. The other two were heated at 135°C to examine the effect of

partial loss of blowing agent.

The specimen heated at 135°C showed a color change, from light beige

to dark brown, with a volume shrinkage on the order of 5-10%; the specimen

heated at the standard 60°C showed very little apparent change.

Upon exposure to the radiant panel, all foam specimens immediately

began shrinking and decomposing with rapid release of white smoke and

gases which burned actively above the pilot burner with a yellowish

flame. On two occasions the decomposition products were able to extinguish the pilot burner which was immediately relighted by the operator.

In about 1.5 minutes, there were flashes of flame near the surface at the

top of the specimen and after 2 minutes flashes extended momentarily down

to 3, 6 and 9 inches. There was no sustained and continuous flaming.

Observable flashes lasted less than 2 seconds, each with a frequency of

about 5 to 10 per minute. Charring of the specimen progressed downward

and reached a maximum at the 12 inch level in about 1.5 minutes.

The test flame spread factor is based on the measured times for

sustained flaming. Since no sustained flames were observed, the factor

is reported as 1 in accordance with the test method.

Because of the inhibiting nature of the f luorocarbon , flammability

of the specimen was reduced considerably compared to rigid foam of con- ventional formulation.

The calculated flame spread index, Ig = Fg x Q: flame spread

factor, Fg; and heat evolved, Q are shown in table 1.
Table 1. Flame Spread Index of Tested Foam Specimens

Specimen Preheat °C Fs Q Is

A 60 1 10.0 10

E 60 1 11.4 11

C 135 1 11.1 11

D 135 1 10.4 10

5.2 Smoke and Combustion Products

The measurements of smoke and gaseous products from specimens preheated at 60°C and 135''C are summarized in table 2, Similar to other

tvpes of rigid foam, smoke generation was higher under flaming than under

non-flaming exposure in the Smoke Density Chamber. However, the smoke

levels were higher than those for rigid foams based on other blowing

agents.

Specimens preheated to 135**C for 24 hours showed lower smoke values

compared to those preheated to 60''C. When heated to 135°C, weak cells in

the specimen appeared to rupture and cause volume shrinkage and some color

change. There was also a weight loss averaging about 30% as a result of

the higher preheat temperature. Losses of some of the fluorocarbon blowing agent may account for the lower level of smoke (averaging 38%) and

gaseous products.

The colorimetric tubes used to detect HBr are also sensitive to HCl.

It was assumed that only negligible HCl was present because of the chemical

composition of the foam and its blowing agent.

7
Table 2. Smoke and Combustion Products

from Specimens in Smoke Density Chamber

Combustion Products, ppm

Initial Smoke

W V M n A 0\ ^ rreneat Exposure weignt'*'* riur rlLW JNU + JNU2 nr "C

60 Non-Flaming 6.5 173 - - - - 6.5 185 18 5 180 3

c o o . z1 /. Q

6.2 163 22 9 360 -

Avg. 168 22 7 270 3

Flaming D . O lUV

6.7 478 30 27 850 22

£ /. 0 .H H /U ZD inJU

6.4 513 50 55 900 15

Avg. 480 40 32 820 18 30

135 Non-Flaming 4.2 158 12 6 260 -

/ 7 1 JO AH

c 1X

Avg. 158 8 6 260 1

135 Flaming 4.7 346 • 12 18 600

4.5 273 10 20 600 30

4.3 268 10 16 500 30

Avg

268 11 18 570 30

*Maximum Specific Optical Density (corrected)

**A11 specimens were 2.5 cm (1 in.) thick prior to preheating.

8
5.3 Loss of Dibromotetrafluoroethane Blowing Agent

The weight percentage of dibromotetraf luoroethane in the foam specimens

was determined by the method outlined in paragraph 4.3. Weight loss as a result of preheating conditions was based on the difference in weight

relative to the original weight. Specimens were sufficiently large in

size to minimize errors.

Table 3 summarizes the results of weight loss due to preheating and

the decrease concentration of C2F4Br2 in the conditioned specimens. The

data were based on averages of at least 2 measurements. The maximum

C2F4Br2 in the specimen was on the order of 13% by weight.

Table 3. Weight-Loss and Percent (Wt.)

of C2 F4Br2 in Specimen After Preheating

Specimen Preheating

Temp Duration

°C Hrs.

Specimen

Weight Loss

%

Wt. Concentration

C2F4Br2

%

Recent None

Aged (Oct. 71) None

Recent 60

Recent 135

Recent 200

Recent 200

In Service "Box 1" None

In Service "Box 2" None

In Service "Box 3" None

24.0

24.0

n.5

2.5

0

0

1.2

11.8

27.0

35.0

0

0

0

13.0

11.9

*

7.6

0

13.0

11.7

13.2

* Not measured, estimated approximately 12%.

The rate of blowing agent release at a temperature of 100°C was

also determined. It was based on the initial slope of the C2F4Br2

concentration-time plot taken at about 10 minute intervals for a period

of 40 minutes. The rate of release of blowing agent was on the order of

3 Wt% per hour. This is a fairly crude estimate although based on several experimental measurements

It is apparent that at elevated temperature, there is a gradual

loss of the blowing agent. At 60°C for 24 hours, a total weight loss

of about 1 Wt% was detected. At 100°C the rate of agent loss was

estimated to be 3 Wt% per hour. At 135°C and 200°C there was a high

rate of loss from the specimen. After 2.5 hours at 200°C, no agent was

left in the specimen. However, soecimens which had been in service for

several years were found to have retained the initial 12 to 13% of

blowing agent.

9
5.4 Flash-Ignition Temperature

Results of flash-ignition temperatures test of the foam specimen

using the procedures of ASTM D1929, are shown in table A.

Table 4. Flash-Ignition Temperature of Foam Specimen

Air Velocity Flash-Ignition Temperature

ft/min °C

550

510, 530

The above represent low and medium velocity flash-ignition temperatures.

Self-ignition temperature, is always higher than the flash-ignition

temperature, though not measured in the test.

5.5 Ease of Ignition

Under the ease of ignition test method described in section 4.5, the

specimen did not undergo sustained ignition. In three separate tests

the specimens did not burn for a period of 1 minute or more after the

exposur;e flame had been removed.

5.6 Heat Release Rate

Specimens of the foam (2.5 cm thick) were also tested in the NBS

Heat Release Rate Calorimeter at irradiance levels of 3.3 and 6.0 W/cm^.

The results are tabulated in table 5. There was no flaming of the

specimens at 3.3 W/cm2 without a pilot. Flaming was observed for all

other ispecimens tested.

5 10

10
Table 5. Heat Release Rate Calorimeter Measurements of the Test Foam

Peak Heat Highest 1 min. Total

Weight Release Average Release Heat

p-f lot T.OQ Q Ra tf> Rate

W/cm2 On/Off % W/cm2 W/cm2 J/cm2 Yes /No

6.0 Off 88.4 11 .

9 .

960 Yes

6 .

Off 89.4 12 .

9.2 890 Yes

6.0 Off a*? 4 9 9 7 9 690 Yes

Averaep 87 0 11 2 8.8 850

3.3 Off 77.9 4.1 / 1 4.1 480 No

3.3 Off 74.7 5 .5.2 690 No

3. 3 Off 74.2 5.0 4 .620 No

Average 76.0 5.0 4.6 600

J . J un / / . Z A . / xes 3.3 On 77.8 8.6 6.4 Yes

3.3 On 78.1 7.9 7.7 550 Yes

3.3 On 78.4 7.2 5.7 620 Yes

Average 78.0 7.1 6.0 600

For comparison, the average values of the heat release at 6^0 W/cm

irradiance for red oak, the test foam and fibrous glass insulation are

shown in table 6.

Table 6. Heat Release Rate of the Test Foam and Other Materials at 6 W/cm

Material

Speciman

Thickness

cm

Peak Heat

Release Rate

W/cm2

Highest One

Minute Average

W/cm2

Total Heat

Release

J/cm2

Red Oak 2.0 18.0 18.0 11250

Test Foam 2.5 ,11.2 8.8 850

Fibrous Glass 2.5 2.1 1.7 350

The highest one minute average heat release rates at 6.0 W/cm^ for the

foam are about one half that of red oak, while the total heat released is an order of magnitude lower. However, the heat release rate of the foam

is about 5 tines that of fiber glasR.

5.7 Fire Growth Experiments

The radiant flux at 7.6 cm above the floor, the air temperature 2.5 cm below the ceiling, and the oxygen concentration of the air leaving the top

of the doorway for the test foam are compared to results for other ceiling

11
materials in tabl*:" 7. The Instilation board and the acoustic tile are

both wood fiber insulation boards. All of the values reported in the

table were the extreme values observed during the first 15 minutes of the

test.

Comparison of test materials is valid only if the test exposure

conditions in the model compartment are Identical, i.e. test condition

1 or 2.

Under both exposure conditions the foam specimen contributed less to

fire buildup in a room than did the fiber glass. However, the much larger

value of heat release rate for the foam Indicates that its contribution

would become relatively greater as the exposure conditions become more

severe. Furthermore, there was a vigorous generation of smoke from the

test foam when it was first exposed to the flame from the elevated

burner during the second set of test conditions.

Table 7. Comparison of the Test Foam with Other

Ceiling Materials in the Model Compartment

Radiant

Condition* Heat Flux Air Oxygen

Test Material Thickness Near Floor Temperature Level

cm. W/cm2 "C % of original

1 Test Foam 2.5 0.31 2A0

1 Fibrous 2.5 0.40 450

Glass

Cellulose 2.5 0.80 580

Insulation

Board

2 Test Foam 2.5 0.19 330 78

2 Fibrous 2.5 0.25 380

Glass

2 Acoustic 2.5 0.81 750 16

Tile

* Condition 1 , burner 7 .

cm from floor anri gas flow rate of 15 .1 1/mln.

Condition 2, burner 28 cm from floor and gas flow rate of 8.5 1/min

6. «^UMMARY

Samples of a rigid urethane foam, incorporating dibrometrafluoroetbane as a blowing agent were subjected to seven laboratory measurements

to evaluate its fire performance characteristics. Eased on the test

foam specimens submitted, the following results were obtained:

1. The weight concentration of the blowing agent in the foam was about 13%. Foam specimens that were aged In service

appeared to retain the original concentration of fluorocarbon agent.

12
2. Release of fluorocarbon blowing agent appears to initiate

at a temperature as low as 60°C. The release rate was on

the order of 3%/hr at 100°C. At temperatures of 135°C

and above, a high rate of agent loss was noted.

3. Surface flammability in terms of a sustained flame spread

index as defined by ASTM E-162, was about 11, low relative

to other rigid foams. However, the foam showed tendencies

to produce momentary flashing.

4. The maximum specific optical density of smoke generated

was 170 and 480 for non-flaming and flaming exposure

conditions, respectively. This is slightly higher than

other rigid urethane foams of comparable density.

5. The flash-ignition temperature measured by the ASTM D

1929 test method was on the order of 530°C.

6. The highest one-minute average heat release rate measured

by the heat release rate calorimeter at an irradiance

level of 6.0 W/cm^, was 8.8 W/cm2 for the test foam.

This compares with 18 W/cm^ for the red oak and 1.7 W/cm^

for fibrous glass insulation.

7. A compartment model experiment showed that the test foam

contributed less to fire build-up than did fibrous glass

insulation similarly located at the ceiling position.

However, its vigorous generation of smoke and significant

heat release rate may outweigh this advantage.

7. ACKNOWLEDGEMENTS

This project was sponsored in part by Naval Research and Development

Center, Carderock, Maryland.

8. REFERENCES

[1] A Standard Method for Surface Flammability of Material Using a Radiant Heat Energy Source - ASTM E 162 "Annual Book of ASTM,

Part 14," American Society of Testing and Material, Phila., Pa.

(1970).

[2] Lee, T. G., "Interlaboratory Evaluation of the Smoke Density

Chamber," Nat. Bur. Stand. (U.S.), Tech. Note 708 (Dec. 1971).

[3] Gross, D., Loftus, J., Lee, T. G. , Gray, V., "Smoke and Gases

Produced by Burning Aircraft Interior Materials," Nat. Bur. Stand.

(U.S.), Bldg. Sci. Ser. 18, 27 pages (Feb. 1969).

[4] "1973 Annual Book of ASTM, Part 27," American Society of Testing

and Materials, Phila., Pa. (1973).

13
Parker, William J., "The Development of a Test for Ease of Ignition

by Flame Impingement" NBS Report 10495, (Feb. 1972).

Parker, W. J., and Long, M. E., "Development of a Heat Release Rate

Calorimeter at NBS," ASTM-STP 502, American Society of Testing

and Materials, pp. 135-151 (1972).
NBS-lUA (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUHLK ATION OR Ri;in:)RT NO. NBSIR-74-456

2. Gov't Accession

No.

3. Recipient's Accession No.

4, TITLE AND SUBTITLE

Evaluation of the Fire Performance of a Dibromotetrafluoroethane - Blown Rigid Polyurethane Foam

5. Publication Date April 1974

6. Performing Organization Code

7. AUTHOR(S)

T. G. Lee, W. J. Parker and Tryon

8. Performing Organ. Report No. NBSIR-74-456

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4906479

11. Contract/Grant No.

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

Naval Ship Research and Development Center

Carderock, Maryland 20034

13. Type of Report & Period Covered Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

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

bibliograpfiy or literature survey, mention it here.) The fire performance characteristics of a dibromotetraf luoroetbane - blmm rigid

polyurethane foam were measured by several laboratory test methods. Measurements

included: surface f laminability , smoke and gases generated at elevated temperature

and during combustion, ignition temperature, rate of heat release, and fire growth

The maximum concentration of the blowing agent in the specimen was approximately

13 Wt%. Specimen density was 0.046 g/cm^. As a function of temperature, release

of blowing agent from collapsed cells began at about 60°C and became considerable

at 135°C. The material had a flame spread index (ASTM E-162) of 11 with smoke

levels of 170 and 480 (maximum, specific optical density) under non-flaming and

flaming exposures, respectively. The measured rate of heat release was 8.8 W/ cm^,

about 5 times that of a fibrous glass insulation. The measured flash ignition

temperature was 530°C for the material.

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)

Dibromotetraf luoroethane; flame spread index; fire tests; heat release rate;

ignition temperature: rigid urethane foam; smoke.

18. AVAILABILITY \X_ Unlimited

I

' For Official Distribution. Do Not Release to NTIS

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' Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. C13

I Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

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UNCL ASSIFIED

20. SECURITY CLASS

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UNCLASSIFIED

21. NO. OF PAGES

14

22. Pr

USCOMI*/l-DC 29042-P74