NBSIR 73-177

Comparison of the Fire Performance

of Neoprene and Flame Retardant

Polyurethane Mattresses

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

April 1973

Final Report

William J. Parker

Prepared for IMaval Ship Engineering Center

Hyattsville. Maryland 20782

NBSIR 73-177

COMPARISON OF THE FIRE PERFORMANCE

OF NEOPRENE AND FLAME RETARDANT

POLYURETHANE MATTRESSES

Wiliiam J. Parker

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

April 1973

Final Report

This document has been prepared for the use of

the Naval Ship Engineering Center. Responsibility

for its further use rests with that agency. NBS

requests that if release to the public is contemplated, such action be taken only after consultation with the Office of Public Affairs

at the National Bureau of Standards.

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

NATIONAL BUREAU OF STANDARDS. Richard W. Roberts. Director
II \ i
TABLE OF CONTENTS

Page

Abstract 1

List of Tables 2

List of Figures • 3

1.0 Introduction 4

2.0 Test Procedure 5

2.1 Full Scale Tests 5

2.1.1 Description of the Test Specimens 5

2.1.2 Conduct of the Tests 6

2.2 Small Scale Laboratory Tests 8

3.0 Results 8

3.1 Observations on Full Scale Tests 8

3.1.1 Conditional 8

3.1.2 Condition //2 9

3.1.3 Condition //3 10

3.1. A Condition #A 11

3.2 Observations on Small Scale Tests 11

3.2.1 Horizontal Tests 11

3.2.2 Vertical Tests 12

3.3 Measurements During Full Scale Tests 13

3. A East of Ignition 14

3.5 Heat Release Rate , 15

3.6 Flame Spread 16

3.7 Smoke and Toxic Gases 16

4.0 Discussion 17

i
5.0 Conclusions 20

6.0 Recommendations 22

7.0 References 22

8.0 Acknowledgements 23

11
COMPARISON OF THE FIRE PERFORMANCE OF NEOPRENE

AND FLALIE RETARDANT POLYURETHANE MATTRESSES

ABSTRACT

Full scale fire tests of a neoprene and two different types of

f lame-retardant polyurethane mattresses were performed in a room sized

compartment at the National Bureau of Standards. The mattresses were

tested in two orientations, horizontal and vertical and with two types

of coverings, a fire retardant treated cotton and a high temperature

nylon ticking, in addition to the bare mattress insert. In addition to

the visual observations, the burning rates, ceiling temperatures, optical

density of the smoke, and the toxic gas concentrations were measured.

This series of tests were repeated on small mattress sections to examine

the relevance of small scale tests as a means of predicting full scale

behavior. The flame spread index was measured with the radiant panel

(ASTM E162); and the smoke and toxic gas concentrations were measured in

the NBS smoke density chamber. Measurements were also performed in the

heat release rate calorimeter and the ease of ignition test apparatus.

Key words: Fire test, ignition, heat release, toxic gases, mattress,

fire retardant, smoke.

1
LIST OF TABLES

I. Test Conditions

II. Maximum Gas Concentrations

III.'^ Smoke, Weight Loss, and Temperature Data

IV. Measurements in NES Smoke Density Chamber

V. Flame Spread and Heat Release
LIST OF FIGURES

1. Plan View of Test Room.

2. Fire Retarded Trested Cotton Covered Polyurethane #2 Mattress Being

Tested in Condition //I.

3. Polyurethane Fattress with High Temperature Nylon Cover Mounted

in Frame For Test Condition //3.

A. Charred Fire Retarded Trested Cotton Cover on Polyurethane Mattress

#2 After Test Condition //I.

5. Damage to Polyurethane //2 Mattress After Test Condition #1.

6. Polyurethane //I Mattress Burning During Test Condition #2.

7. Polyurethane #2 Mattress Burning During Test Condition //2.

8. Burning of Polyurethane //2 Mattress in Test Condition //3.

9. Charred Fire Fetardant Treated Cotton Cover on Neoprene Mattress

Specimen After Horizontal Test in the Hood.

10. Bare Polyurethane //2 Mattress Specimen 20 Seconds After Ignition in

the Horizontal Position in the Hood.

11. Bare Polyurethane #2 Mattress Specimen 7 Minutes After Ignition in

the Horizontal Position in the Hood.

12. Vertical Test of a Polyurethane #2 Mattress Specimen Having a High

Temperature Nylon Cover with Snaps at the Front End.

13. Flames Occurring at Snapped End of High Temperature Nylon Cover on

the Polyurethane //2 Mattress Specimen at A Minutes.

14. Total Involvement of the Polyurethane #2 Mattress Specimen Having the

High Temperature Nylon Cover with Snapped End.

15. Em.pty Charred Nylon Shell Near the End of the Test of the Polyurethane #2 Mattress Specimen with the Snapped End.

3
COMPARISON OF THE FIRE PERFORMANCE OF NEOPRENE

ANT) FLAME-RETARDANT POLYURETHATT MATTRESSES

1.0 INTRODUCTION

Burning mattresses may generate large quantities of heat which

could contribute to the severity of any fires in which they are involved.

Further, if large quantities of smoke and toxic gases are released during

the burning of the mattresses, these may circulate to other areas and

cause a potentially serious life hazard. In addition, the reduction

in visibility caused by the smoke interferes both with efforts to

escape the hazardous areas and with efforts to suppress the fire. This

is a particularly serious problem aboard ship. A project to evaluate

several aspects of the fire performance of burning mattresses was undertaken at the National Bureau of Standards under sponsorship of the Naval

Ship F.ngineering Center.

Although the mattresses are horizontal in use they may be oriented

vertically in storage. Since the potential fire hazard may be quite

different for the two cases, tests were performed in both orientations.

In order to compare the ignitability , heat release rate, and the

smoke and toxic gas generation for the various types of mattresses and

covers being considered for use by the Navy, twelve fire tests on fullsized mattresses were conducted in a 100-sq. ft. room, in the NBS fire

laboratory. Six mattress and ticking combinations were tested in a

vertical, well ventilated condition, and six in a horizontal, poorly

ventilated condition.
In addition, small scale laboratory tests were conducted to measure

the degree of correlation between small and full scale tests and thus

provide a potential basis for future material specifications. Comparisons were made of the heat release rate and the smoke and toxic gas

production for each of the mattress and cover combinations with the

1 2 heat release calorimater and the smoke density chamber . Ignition and

3 flame spread data were also obtained with the ease of ignition test

4 and the ASTM, E162 radiant panel.

All of the mattresses tested on this project have passed the cigarette ignition test of the mattress flammability standard^ DOC-FF4-72. On

the other hand they would all be consumed in the event of a severe fire

exposure. An intermediate exposure level was used in these tests to

show the greatest differences in response to fire among the mattresses

and cover combinations. Currently, mattresses and tickings are required

to meet the flammability criteria in the military specifications,

MIL-M-18351 and CCC-C-436 respectively.

2.0 TEST PROCEDURE

2.1 Full Scale Tests

2.1.1 Description of Test Specimens

The mattresses included neoprene and two different types of flamere Lardant polyurethanes , labelled //I and #2 in this report. The numbers

relate to the order in which they were tested. The mattresses were tested

bare, and with two types of ticking, flame retardant treated cotton

(FR cotton) and high temperature nylon (HT nylon) . The mattresses were

76 inches long, 26 inches wide and 3 inches thick.

5
2.1.2 Conduct of Tests

Full scale fire tests of the mattresses from three manufacturers

were run on successive days. On each day the mattresses of a single

manufacturer were burned under the four different test conditions listed

in Table I.

In condition 1 the mattress had a fire retardant treated

cotton (FR cotton) cover and was located in the horizontal

position with the room ceiling vent closed.

In condition 2 the mattress had no cover and was also

located in the horizontal position with the ceiling vent

closed . ..

.

In condition 3 the mattress had a high-temperature nylon

(HT nylon) cover and was located in a vertical position with

the ceiling vent open and the exhaust fan operating.

Condition 4 was the same as condition 3 except that a FR

cotton ticking was used instead of the HT nylon.

Under normal cool air conditions the exhaust fan draws 1500 CFM of

air through the 14-1/2 x 15 inch ceiling vent. The 34 x 80 inch door

into the room where the mattresses were burned was open for all of the

tests. The floor of the room was 9 feet, 7 inches wide, and 10 feet,

5 inches long with a ceiling height of 8 feet. The floor plan is shown

in Figure 1.

The mattresses were burned on a platform supported by load cells to

provide a continuous measure of the burning rate during the test. For

the horizontal condition they were centered on an asbestos cement board

support 84 inches long and 34 inches wide. A mattress being tested in

6
condition 1 is shown in Figure 2. The vertical specimens were mounted In

an angle iron support frame as sho\TO in Figure 3.

In the horizontal position the fire was started by Igniting 50 ml of

ethanol placed on the center of the top surface of the mattress. In the

vertical orientation the fire was started by Igniting 500 ml of ethanol in

a steel pan 80 Inches long, 3-1/4 Inches wide, 2 inches deep, and

located 1 inch below the mattress. Without the mattress in place the

alcohol burned for 3 minutes. In the presence of the mattress the alcohol

flames persisted for as long as 5 minutes.

The quantities of ethanol specified in this procedure were determined

by preliminary tests aimed at finding an intermediate exposure level

which would provide the maximum distinction between the fire performances

of the mattresses.

The concentrations of the toxic gases; CO (carbon monoxide), HCl

(hydrogen chloride), HCN (hydrogen cyanide) and the oxides of nitrogen;

were measured with colorometric detector tubes at a point 4 inches down

from the ceiling and 8 inches from the center of the rear wall of the

room. A thermocouple was located on the ceiling directly above the

mattress to obtain a relative measure of the rate of heat production.

The optical density of the smoke was measured over a horizontal light

path 10 feet, 5 inches long located 5 feet, 2 inches above the floor and

13 inches from the wall farthest from the mattress. See Figure 1. A

tungsten filament lamp and a collimating lens were used to produce the

light beam. A phototube with an S-4 cathode surface was used to measure

the transmitted light.

7
2.2 Small Scale Laboratory Tests

All of the full scale tests were modeled by burning 8-1/2 inch x

8-1/2 inch sections of the mattress and ticking combinations in a standard

chemical hood. Motion picture and slide coverage was provided for these

small scale tests as well as for those run at full scale.

As in the full scale tests, the horizontal tests in the hood used

50 ml of ethanol on the upper surface for ignition. The vertical tests

in the hood utilized 50 ml of ethanol which provided the same depth of

fuel in the pan below the mattress as was provided in the full scale test.

Consequently the burning times of the alcohol were approximately the same

for the small and full scale tests.

A 2 The radiant panel and the smoke density tests were run on 3/4 inch

thick specimens for all the mattress and cover combinations. Both flaming

and non-flaming modes were used in the smoke density test, and the toxic

gas concentrations were measured at the same time.

In order to handle the melting specimens in the ease of ignition

3 test an insert was provided in the holder to catch the melting material

and permit it to burn in contact with the lov;er edge of the specimen.

The heat release rate calorimeter''' specimens were burned in a pan attached

to the front of the holder. The heat of the combustion was also measured

with the oxygen bomb calorimeter for each of the mattress and ticking

materials . , ' :•

3.0 RESULTS

3.1 Observations on the Full Scale Tests

'3.1.1 Condition 1

The FR cotton covers prevented complete fire involvement in any of

8
the mattresses tested in the horizontal position. Some melting and

pyrolyzing of both polyurethanes occurred to a depth of less than 1 inch

directly under the area in which the ethanol was burned. Flames appeared

to persist only as long as the alcohol was present. The FR cotton cover

was charred over the burning area which was approximately 6 inches in

diameter. This char layer prevented the direct exposure of the mattress

to the flame. The charred cover is shown in Figure 4 and the damage to

the polyurethane underneath is seen in Figure 5.

A thin hard crust was formed on the neoprene mattress surface

directly below the charred area of the FR cotton cover. Underneath

the crust the neoprene appeared to be unaffected.

3.1.2 Condition 2

The differences in the fire behavior among the mattresses was more

pronounced without the covers. The neoprene mattress again formed a thin

crust over the area under the ethanol spill with no damage beneath.

The polyurethane //l mattress continued to burn in the area of the

ethanol spill until the full thickness of the mattress was burned through.

The coupling between the flame and the uncovered mattress was sufficient

to maintain the melting and pyrolyzing of the polyurethane until the

bottom of the mattress was reached. However, there was no tendency for

the fire to spread beyond the original area. The burning of this

mattress is shown in Figure 6.

The polyurethane #2 mattress burned down through the complete thickness and then the fire spread laterally until the whole mattress was

consumed. Tb.e burning of this mattress is shown in Figure 7. The

polyurethane #2 mattress seemed to melt more readily and the liquid

9
produced was more flammable than that of the polyurethane #1 mattress.

The feeding of the flame by the melted material flowing into the flame

zone caused the lateral spread of fire along the polyurethane #2 mattress.

3.1.3 Condition 3

In the vertical position the polyurethane mattresses 1 and 2 started

to burn at the ends where the ticking had snap fastenings so that some of

the mattress was exposed at the top and bottom corners. Openings at

these corners provided a source of air at the bottom and an exhaust vent

at the top. Fire started at the snapped end and progressed into the

mattress with flaming combustion inside of the HT nylon cover. The

progress was slow in the polyurethane //I mattress and about 24 percent

of it was consumed by the time the fire went out in twelve minutes. In

a second full scale test of this mattress, with the snapped end reversed,

it appeared to be burning to completion but very slowly. The polyurethane

#2 mattress was 90 percent consumed in 24 minutes inside of the HT nylon

cover, which was charred and deformed. The fire was put out at this time

because it was apparent it would burn to completion. The burning of the

polyurethane //2 mattress is seen in Figure 8. The role of the opening

at one end of the ticking was quite important to ignition and fire

propogation in these two cases.

For the neoprene, smoldering combustion started at the end away from

the snaps and progressed very slowly along the mattress. At 35 minutes,

after 1/3 of the mattress had been consumed it was apparent that the

smoldering would eventually consume the whole mattress so the test was

stopped.

10
3.1.4 Condition 4

The polyurethane #1 mattress with the FR cotton cover started to

burn at the snapped end and the fire propagated slowly along the length

as it did with the HT nylon cover. When the test was stopped at 35 minutes

the mattress was almost completely consumed but the upper part of the FR

cotton cover at the far end was only slightly affected. The flames

broke through the bottom of the cover allowing the melted polyurethane

to drip and burn in the pan beneath the mattress.

The polyurethane //2 mattress flamed strongly at one minute, at the

end of the mattress away from the snaps. The mattress was essentially

consumed in 13 minutes, except for some remaining liquid polyurethane

which was burning in the pan when the fire was extinguished at 16 minutes.

For the neoprene mattress the flames were out in 6-1/2 minutes.

Smoldering continued until it was apparent that the whole mattress

would be destroyed. The test was stopped in 35 minutes with about one

third of the mattress consumed.

3.2 Observations During Small Scale Tests

The results of the horizontal tests in the hood with the 8-1/2 x

8-1/2 X 3 inch specimens qualitatively duplicated those of the full scale

tests .

3.2.1 Horizontal Tests

The polyurethane mattress specimens covered with FR cotton burned

as long as the alcohol lasted which was about 5 minutes and then went

out with a small amount of melting and loss of material just below the

charred cotton cover. The flames were out on the neoprene specimen in

11
about 2-1/2 minutes, with some crusting of the surface below the cover.

The charred cotton cover is seen in Figure 9.

In the case of the bare horizontal mattress the neoprene specimen

stopped flaming at 4-1/4 minutes when the alcohol near the surface burned

out. Much of the alcohol seeped through to the bottom of the mattress

as it did in the full scale test, due to the porosity of the neoprene.

The bare polyure thane /'l specimen burned through the complete thickness of the mattress in the region of the alcohol spill, but the fire did

not spread to the edge of the specimen. The flames were out in 8 minutes.

- The bare polyurethane //2 specimen is shown in Figure 10 twenty

seconds after ignition. It burned through to the bottom in 4-1/4 minutes.

The burning zone reached the edge of the specimen in 5 minutes. All of

the solid was melted or consumed within 6 m.inutes and the flaming ceased

with the complete consumption of the sam.ple, except for some residual

char, in 12 minutes. The burning of the pool of polyurethane at 7 minutes

is seen in Figure 11.

3.2.2 Vertical Tests

The findings of the vertical tests of the small scale 8-1/2 x 8-1/2

X 3 inch specimens in the hood were also in agreement with those of the

full scale tests. The flames went out in 3-1/4 and 4-1/2 minutes,

respectively, for the polyurethane #1 and //2 mattress specimens with the

HT nylon covers without a snapped end. There was only a 15 percent

weight loss in the first case and 12 percent in the second one.

The vertical tests were repeated with one snapped end, so that the

upper and lower corners of one edge of the specimen were exposed as they

were in the f uJ 1 scaJ.e tests. The snapped end is seen in Figure 12 for

12
the polyurethane #2 specimen and the flaming from the upper corner is

seen in Figure 13 followed by complete involvement in Figure 14. This

specimen burned to completion in 35 minutes inside of the HT nylon cover

which remained as an empty charred shell as seen in Figure 15. The

polyurethane #1 specimen did not burn to completion. The comparison

between the two types of mattresses and the role of the snapped end seems

to be adequately demonstrated by the small scale tests.

The vertical neoprene mattress specimens were completely consumed by

smoldering in the hood for one hour both with the HT nylon and the FR

cotton covers, again duplicating the behavior of the full scale tests.

The neoprene mattress specimens in the hood did not have snapped ends but

the full scale tests did not indicate that the edge exposure was important

for these mattresses which burned in a smoldering mode.

The FR cotton covered polyurethane #1 and //2 specimens were completely consumed ins6de of their charred FR cotton shells in 12-1/4 and

10 minutes respectively. These covers did not have snaps.

3.3 Measurements During Full Scale Tests

The maximum concentrations of the toxic gases in the room during

the full scale tests are recorded in Table II. The absolute concentrations are difficult to interpret but the comparison between mattress

types for a particular test condition is meaningful. For the active

burning conditions 3 and 4, the HCl levels of the neoprene were definitely

higher than for the polyure thanes The low values of Hcl for neoprene in

conditions 1 and 2 are a result of the very small am^ount of burning that

took place. The other toxic gases are more dominant for the treated

poly urc th.anes . The polyurethane //I mattress which did not burn as

13
vigorously as the polyurcthane //2 mattress produced more CO in conditions

3 and . Ihese findings are reasonable in liglit of the chemical composition of the different materials.

The maxirnuin optical density (absorbance) of the smoke per foot, the

burning rate, total weight loss, burning time, and the maximum ceiling

temperature are tabulated in Table III. The highest smoke densities were

obtained for the polyurethane mattresses where the light level became too

low to measure for an extended period of time for polyurethane //I in

condition ^ and polyurethane #2 during condition 2. The sensitivity of

the measurement was such that the smallest transmission that could be

measured was 0.001 vjhich corresponds to a maximum optical density per

foot of 0.3.

The maximum burning rate was highest for the polyurethane #2

mattresses and lov;est for the neoprene. For the horizontal tests the

specimen burned until a constant weight loss was achieved. The vertical

tests which were extended much further in time were cut off when it was

apparent that a complete burnout would occur. The exception was the

polyurethane #1 mattress in condition 3 which went out in 12 minutes.

The test was repeated with the snapped end of the mattress reversed.

In this case, the snapped end near the door, 60 percent of the mattress

was consumed by the time the test was stopped at 35 minutes. The higher

ceiling temperatures observed above the polyurethane #2 mattresses reflect

the h.igher burning rates.

:,. 3.4 Ease of Ignition

By providing a container at the base of the specimen to catch the

melted material in the ease of ignition test apparatus, ignition was

14
sustained in the polyurethane //2 mattress specimen after a 70 second

exposure, when the thickness was 1-1/2 inches. For smaller thicknesses

of the polyurethane #2 specimens and for all thicknesses of the polyurethane #1 specimens, including the full thickness of the 3 inch

mattress, the specimen melted completely without sustaining a flame.

This included exposure tim.es up to 7 minutes. The neoprene mattress

did not flame at any thickness, but after a 105 second exposure a 3 inch

thick specimen continued to smolder until it was completely consumed,

except for a thin hard crust formed on all surfaces of the specimen.

These tests showed the polyurethane //2 mattress to be the most easily

ignited by a flame and the polyurethane #1 mattress to be the least

readily ignitable. This is contrary to the full scale tests and

the tests in the hood in which the polyurethane //I would ignite in a

horizontal location but the neoprene would not, even in a smoldering

mode. Thus the ease of ignition test did not provide correlatable

information on the ignitability of mattresses.

3.5 Heat Release Rate

The heat release rates given in the Table IV are based on the

average of 3 determinations. The greatest differences in heat release

rate occur for the bare mattress where the rates for the polyurethanes

are much higher than for the neoprene. The cover tends to minimize the

difference by impeding the heat flow into the mattress and reducing the

2 heat released. The incident heat flux of 6 W/cm used in the test would

be produced by a fairly intense fire in a compartment in which case all

oi the mattresses would burn fairly rapidly. The densities and heats of

combustion of the pads and tickings are also listed in Table IV.

15
3.6 Flame Spread

Specimens 6 inches wide, 18 inches long, and 3/A inches thick of the

three different types of mattresses were measured with the radiant panel

in accordance with the ASTM El 62 procedure. The specimens were either

bare or covered with FR cotton or HT nylon ticking and were restrained

in the holder with 1 inch mesh chicken wire. Specimens of the two types

of ticking were also tested separately.

The flame spread ratings given in Table IV reflect the difference

in burning behavior of the full size mattresses. The highest flame spread

was for the polyurethane y/2 and the lowest was for the neoprene. The

flame spread number indicates that HT nylon is a better ticking than FR

cotton for the polyurethane, but not as good for the neoprene.

' 3.7 Smoke and Toxic Gases

The optical density of the smoke and the concentrations of HCN, HCl,

CO, and the oxides of nitrogen were measured for both the smoldering and

flaming modes of combustion in the MBS smoke chamber for all of the

mattress and cover combinations and the mattresses and covers by themselves. These are recorded in Table V. There is an exceptionally low

optical density for the flaming mode for polyurethane //2. Since the

flaming areas on the polyurethanes were nearly always accompanied by

smoldering regions in the full scale tests the significance of this low

value is not too important. Although the polyurethanes had somewhat lower

smoke density values for the smoldering mode they had significantly

greater areas of involvement in the full scale tests due to their greater

f lammabili ty . Thus it is difficult to make predictions regarding the

16
smoke productiAn levels for the fii] 1 ^;cale tests where the area of InvoLvement is (|ulLe unpred 1 r tab ] c . I'owi-vfr, Llie total amount of Hmoke

produced should be comparable with the smoke densities measured in the

smoke density chamber. The smoke measurement in the room is more a

measurement of the rate of production than a measurement of the total

smoke produced. The smoke chamber measures the total smoke produced.

The indicated toxic gas concentrations are similar except for the HCl

which are an order of magnitude higher for the neoprene.

4.0 DISCUSSION

The objectives of this series of tests were: (1) to provide experimental evaluations on the full scale fire performance of three particular

mattresses and two particular tickings of interest to the Navy, (2) to

provide small scale laboratory data suitable for judging the performance

of the mattress combinations in fire situations, and (3) to compare the

results of the small scale and full scale tests in order to assess the

need for the latter in the future. To begin with these pads and tickings

were chosen because of their assumed low fire risk. They would all

easily pass the mattress flammability standard.^ On the other hand they

would all contribute significantly to the severity of a fully developed

fire. It was necessary to pick some realistic intermediate set of

conditions wherein the differences between them would become apparent.

One fully instrumented test was run on each combination and orientation.

Because borderline exposure conditions were chosen to amplify the

differences in performance, one could expect a certain amount of variability between tests. This could not be observed without running several

replications of each test. On the other hand the number of tests which

17
would be required to make a high degree of statistical correlation would

have been prohibitive on a small project. Due to the lack of repetition

the numerical results of the full scale tests described in this report

should be considered to be approxj in£) te . However, the qualitative

differences in the burning behavior of these mattresses does seem to

be adequately established and to be consistent with the small scale tests

and the standard laboratory tests.

The performance of the neoprene mattress was superior to that of the

two polyurethanes in the full scale tests, based on the burning rate,

heat release rate, and damage to the mattress. This was in agreement

with the results of the small scale tests, the radiant panel test, and

the heat release rate calorimeter.

, The neoprene mattress was slightly better than the polyurethanes in

terms of observed smoke levels in the room. This finding was not in

agreement with the smoke density chamber which rates the polyurethanes

somewhat better than the neoprene. The principal reason for this difference is that the smoke density chamber retains all of the smoke that is

produced and the reported maximum optical density does not depend on the

rate of production. In the large scale tests smoke was continually

removed through the door and through the vent in the case of the vertical

tests so that the observed smoke level depended on the rate of production.

Because of the lower burning rate of the neoprene its rate of smoke production was less. The unpredictable area of involvement of the mattresses

and the burning of the material inside of the cover under a reduced oxygen

concentration were other complicating factors.

18
The results of the tests indicate that the radiant panel would be

ideally suited to bringing out the differences in burning behavior of

the mattresses. Bare neoprene and neoprene with each of the covers had

flame spread ratings of less than 25 measured with the E162 test whereas

the bare and covered polyure thanes all had flame spread ratings in excess

of 25 by the same test.

The smoke density chamber could give a maximum potential of smoke

level resulting in a closed room, but does not give an adequate indication of the smoke level that would result from a mattress fire in a

room where either forced ventilation or free circulation through a

doorway is involved.

Although the burning rates and smoke levels were not measured in the

small scale tests, the qualitative agreement in the observed burning

behavior with the full scale tests suggest the possible development of

a small scale test in which the mattress specimens are burned on a

weight loss platform in a ventilated chamber with a smoke meter installed

inside. In this way both smoke production and burning behavior could be

evaluated in the same cham.ber under realistic conditions.

The optical densities per foot (H/H) in the full scale tests are

several orders of magnitude less than the specific optical densities

(D ) measured in the NBS smoke chamber. The reason for this can be

s illustrated for the case of the vertical test on the neoprene with the

HT nylon cover. was measured to be 325 on a specimen 3/4 in. thick.

For the 3 in. mattress it should be 1300. If all of the smoke had

been contained in the measurement room the D/2, would be given by

D/f = (A/V)D = 22.3 per foot where A is the area of one side of the

s

19
mattress and V is the volume of the room. Forty percent of the mattress

was consumed in 35 minutes. The air was removed through the exhaust vent

at the rate of 1500 cubic feet per minute. This would result in 66 room

air changes during the burning period. The above value of D/£ should be

multiplied by the fraction of the mattress consumed and divided by the

number of air changes. This yields an average value of 0.13 per foot.

This is an order of magnitude calculation. The smoke carried out

through the doorway vjould reduce this number somewhat farther. The

measured maximum was 0.15 per foot. The closeness of these numbers

indicates that the smoke chamber can give an order of magnitude approximation of the smoke level.

The same calculation on the vertically tested FR cotton covered

neoprene would yield a value of about 0.2 and the peak measured

value was about 0.1.

5.0 CONCLUSIONS

The following conclusions are drawn from the results of the full

scale tests, the small scale testsc and the standard laboratory tests.

They refer to the three mattress types tested on this project.

(1) Small level fires, as simulated by the lighted alcohol

spill on the top surface, are not sufficient to ignite

. . a horizontal mattress if it is protected with a fire

retardant treated cotton or high temperature nylon

ticking. A neoprene mattress will not ignite under

these conditions, even without a cover.

^2) If the fire exposure is intense enough all of the

mattress and cover combinations will burn.

20
(3) For intermediate level fite exposures the polyurethane

//2 burns much more rapidly than the other two mattresses.

The neoprene mattress burns the slowest of the three and

the burning is confined to the smoldering mode.

(4) The smoke concentrations (optical densities) produced

were similar among the polyurethane mattresses but lower

for the neoprene.

(5) The concentration of HCl was highest for the neoprene

while the concentration of the other toxic gases were

somewhat higher for the polyure thanes

(6) The qualitative behavior of the full scale mattress

burns can be predicted from small scale tests with

8-1/2 X 8-1/2 X 3 inch specimens.

(7) The burning rates were highest for the mattresses with

the highest flame spread ratings obtained with the

radiant panel and with the highest heat release rates

obtained with the heat release rate calorimeter.

(8) The exposure of the pad near the snapped end of the

mattress cover increases considerably its vulnerability

to fire.

(9) The fire retardant treated cotton ticking provides

considerable protection to the polyurethanes ; and the

high temperature nylon provides even more. However, the

presence or absence of a ticking makes very little

difference to the fire behavior of a neoprene mattress.

21
(10) In overall rating of fire hazard the neoprene mattress

would appear to present the least contribution to the

fire hazard under an intermediate level fire.

6.0 RECOMMENDATIONS

It is recoininended that

(1) The E162 radiant panel test should be used to rank

mattresses in regard to their burning behavior.

(2) A small scale test should be developed to measure the

rate of smoke production of different m.attress materials

in order to compare the smoke levels which would be

achieved in a controlled ventilation compartment

involved in a mattress fire. The small size mattress

specimens should be burned in the manner specified in

this report so that the smoke production rate properly

reflects the burning behavior of the mattresses in a

real fire.

(3) The NBS smoke density chamber can be used as a measure

of the total smoke produced and could be used to

estimate the smoke distribution in the air handling

system.

7.0 REFERENCES

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

Ccilorimeter at NBS," Ignition, Heat Release, and Noncombustibility

of Materials , ASTM STP 502, American Society of Testing and Materials,

1972, pp. 135-151.

22
2. D. Gross, J. J. Loftus, and A. F. Robertson, "Method for Measuring

Smoke from Burning Materials," ASTM Special Technical Publication

No. A22 (1967).

3. W. J. Parker, "The Development of a Test for Ease of Ignition by

Flame Impingement - Progress Report," September 3, 1971.

4. ASTM E162-67, "Surface Flammability of Materials Using a Radiant

Heat Energy Source," ASTM Book of Standards, Part 14, page 558,

(1972).

5. "Flammability Standard for Mattresses, DOC FF 4-72", Federal Register,

Volume 37, Number 110, June 7, 1972, pages 11362-11367.

8.0 ACKNOWLEDGEMENT

I am endebted to Jim Conway of the Philadelphia Naval Shipyard

Code 134.1 for his helpful suggestions and observations during the development and running of these tests.

I also appreciate the contribution made to the project by all of the

technicians in the Building Fires and Safety Section.

23

TABLE I TEST CONDITIONS

Test Room

Condition Ticking Orientation Vent Fan

1 Fire retardant horizontal closed off

treated cotton

2 none horizontal closed off

3 High temperature vertical open on nylon

4 Fire retardant vertical open on treated cotton
TABLE II MAXIMUM GAS CONCENTRATIONS

Test CO HCl HCN NO + NO

Tl — 10

51 — 10 10 1.5

U2 250 10 — 3

T2 0

52 100 90 5 5

U3 750 35 25 8

T3 150 • > 100 2.5 2

53 300 40 5 20

U4 750 55 25 5

T4 100 > 100 5 Trace

84 300 • > 0 10 30

U refers to Polyurethane #1

T refers to Neoprene

S refers to Polyurethane //2
TABLE III SMOKE, WEIGHT LOSS, AND TEMPERATURE

DATA IN FULL SCALE TESTS

Test Maximum Maximum Total Burning Maximum

Optical Burning Weight Time Ceiling

Density Rate Ixiss (Min) Temperature

of Smoke (Ibs/min) (%) (^c)

(per foot)

Ul 0.003 2.1 5 41

Tl 0.002 1.1 2.3 31

51 0.001 1.5 5 31

U2 0.07 11 8 34

T2 0.0005 0.9 1.8 20

52 >0.3 3.5 100 23 402

U3 0.09 0.42 24 12 60

U3' 60 35*

T3 0.15 0.19 40 35* 81

53 0.09 1.0 90 24* 188

U4 >0.3 0.31 81 32* 62

T4 0.09 0.23 42 35* 71

54 0.14 3.5 97 16* 190

U refers to Polyurethane #1.

T refers to Neoprene.

S refers to Polyurethane #2.

U3' was an uninstrumented repeat of U3 with the snapped end reversed.

* Fire v/as stopped at this time when it appeared obvious that the

mattress would continue to burn to completion.
TABLE IV FLAME SPREAD AND HEAT RELEASE

Pad Ticking Flame

Spread

(E162)

Heat

Release

Rate-

(W/cm )

Heat of

Combustion

(BTV/lb)

Mnifrl<il

Density

Neoprene

Neoprene

Neoprene

Polyurethane

#1

Polyurethane

#1

Polyurethane

//I

Polyurethane

#2

Polyurethane

//2

Polyurethane

#2

None

None

None

FR Cotton

HT Nylon

None

FR Cotton

HT Nylon

None

FR Cotton

HT Nylon

FR Cotton

HT Nylon

4

4

22

140

242

65

477

515

186

2

1

6.5

14

5.4

18

11

8.0

22

14

9.7

10,140

9,130

10,700

7,090

11,400

3.7 Ibs/ff

3.2 Ibs/ff

3.5 Ibs/ff

7.2 oz/yd'

5.7 oz/yd'
TABLE V >^EASUREiMENTS IN" NBS SMOKE DENSITY CHAMBER

Mattress

Pad

Cover Smoke Mode

F- flaming

S-smoldering

Gas Concentration (ppm)

HON HCl CO N04-NO,

Neoprene None 485

440

10

8

700

200

1000

500

13

2

Neoprene FR Cotton 602

516

25

25

1000

350

1200

1000

Neoprene HT Nylon 379

325

F

S

25

10

600

300

700

500

12

2

Polyurethane

#1

None 472

240

F

S

50

2

75

35

1500

125

15

1

Polyurethane FR Cotton 432

248

F

S

25

12

45

40

750

400

Polyurethane

#1

HT Nylon 477

176

F

S

65

2

80

25

2500

125

10

1

Polyurethane

#2

None 50

295

F

S

25

5

30

4

500

200

40

3

Polyurethane

#2

FR Cotton 419

288

F

S

25

12

40

12

1000

750

30

12

Polyurethane

^'2 HT Nylon 331

262

F

S

25

10

25

2

1000

400

40

1

None FR Cotton 41

42

F

S

10

5

20

20

500

250

10

1

None HT Nylon 19

6

20

1

500

20

15

1

9'-7"

PHOTO DETECTOR

in

I 'O

0—GAS SAMPUN6 POINT

LOCATION OF

VERTICAL

MATTRESS

LOCATION OF

HORIZONTAL

MATTRESS

CEIUN6 VENT

(TO EXHAUST

FAN)

^

LIGHT SOURCE

OPEN DOOR

MOTION PICTURE

CAMERA

Figure 1. Plan View of Test Room

Figure 3. Polyurethane #2 Mattress with

High Temperature Nylon Cover

Mounted in Frame for Test

Condition #3.
Figure 4. Charred Fire Retarded Treated

Cotton Cover on Poiyurethane

Mattress #2 after Test

Condition #1.



Figure 8. Burning of Polyurethane if'i Mattress in Test Condition

#3.
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FORM NBS-1 14A (1-71 ) U.S. DEPT. OF COMM. 1. PU B LIC .-^TION OR REPORT NO. 2. Gov't Accession

BIBLIOGRAPHIC DATA mdctd 7-3 177 SHEET NBSIR 73-177

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Oomparison of the Fire Performance of Neoprene and FlameRetardant Polvurethane Mattresses

5. Publication Date

6. Performing Organization Code

7. AUTHOR(S)

William J. Parker

8. Performing Organization

NBSIR 73-177

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4619473

11. Contract/Grant No. MIPR NO. 72-6131F

12. Sponsoring Organization Name and Address Naval Ship Engineering Center

Hyattsville, Maryland 20782

13. Type of Report & Period Covered

Final ~ 1972

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

6. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Full scale fire tests of a neoprene and two different types of f lame-retardant

polyurethane mattresses were performed in a room sized compartment at the National

Bureau of Standards. The mattresses were tested in two orientations, horizontal

and vertical and with two types of coverings, a fire retardant treated cotton and

a high temperature nylon ticking, in addition to the bare mattress insert. In

addition to the visual observations, the burning rates, ceiling temperatures,

optical density of the smoke, and the toxic gas concentrations were measured. This

series of tests were repeated on small mattress sections to examine the relevance of

small scale tests as a m.eans of predicting full scale behavior. The flame spread

index was measured with the radiant panel (ASTM E162) ; and the smoke and toxic gas

concentrations were measured in the NBS smoke density chamber. Measurements were

also performed in the heat release rate calorimeter and the ease of ignition test

apparatus

.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Fire retardant; fire test; heat release ignition; mattress; smoke; toxic gases.

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