—ftos- report has been prepared

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NATIONAL BUREAU OF STANDARDS REPORT

8933

REVIEW OF FABRIC FLAMMABILITY TEST METHODS

by

M. W. Sandholzer

and

M. P. Vaishnav

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NAT IONAL BUREAU OF STANDARDS

The Nation Bureau of Standards is a principal focal point in the Federal Government for assuring

maximum application of the physical and engineering sciences to the advancement of technology in

industry and commerce. Its responsibilities include development and maintenance of the national standards of measurement, and the provisions of means for making measurements consistent with those

standards; determination of physical constants and properties of materials; development of methods

for testing materials, mechanisms, and structures, and making such tests as may be necessary, particularly for government agencies; cooperation in the establishment of standard practices for incorporation in codes and specifications; advisory service to government agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; assistance

to industry, business, and consumers in the development and acceptance of commercial standards and

simplified trade practice recommendations; administration of programs in cooperation with United

States business groups and standards organizations for the development of international standards of

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its Institutes and their organizational units. Ia tiiatt foj ^ t i< Si

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* Located at Boulder, Colorado 80301. ** Located at 5285 Port Royal Road, Springfield, Virginia 22171.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

42102-12-4212124 July 19, :L965 8933

REVIEW OF FABRIC FLAMMABILITY TEST METHODS

by

M. W. Sandholzer

and

M. P. Vaishnav

IMPORTANT NOTICE NATIONAL BUREAU OF STAf

for use within the Government. Bi and review. For this reason, the f whole or in part, is not authorize Bureau of Standards, Washington,

the Report has been specifically pr

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

accounting documents intended

bjected to additional evaluation

sting of this Report, either in )ffice of the Director, National he Government agency for which

es tor its own use.

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

REVIEW OF FABRIC FLAMMABILITY TEST METHODS

by

M. W. Sandholzer and M. P. Vaishnav

ABSTRACT

A review of some of the technical aspects of current

textile flammability standards has been carried out. An

experimental study of the test procedure of CS191-53 was

made to determine the importance of certain variations in

practice and interpretation among laboratories. A standard

procedure was selected on the basis of the study, and a comparative classification of about fifty current clothing

and bedding fabrics by CS191-53 and NFPA Standard 702 was

developed. Data on the comparative heat output of the

fabrics were obtained and a possible additional criterion

of flame intensity outlined.

1. Introduction

The Federal Flammable Fabrics Act has been in force since July 1 of 1954,

a period of more than ten years, and has generally been considered effective

in achieving its purpose. Recently, however, the possibility of providing

increased public protection has been raised, and various suggestions for

amendment of the law have been offered. To develop a basis of information from

which to judge the desirability of recommending changes in the law, the

Secretary of Commerce requested a study of its operation and effectiveness to

date, and a review of the commercial standards on which it is based.

In organizing such a study, it appeared t tat useful and definitive information could be obtained primarily from three main areas of investigation.

Of these, the collection of data on actual accident experience was considered

most important, but it would require facilities of a type the NBS does not

presently have available. Facilities suitable for the purpose might be

provided by the Public Health Service if funding support could be supplied.

Some information, however, is already available from partial and regional

studies and from other countries. Several years ago, an investigation

sponsored jointly by the American Academy of Pediatrics and the National Fire

Protection Association compiled data on nearly one hundred ignited clothing
2

accidents, and in California, £b® Fir® -Marshal f s Office has been

particularly interested in collecting pertinent records. In Great

Britain, the Fire Research Static |1] has been able to obtain fairly

comprehensive recard® for that CMitry, the National Research.

of Canada has made an effort t© e©^prile information through the cooperation

of local fire protection units. While wpm: of these sources provides a valid

representation of the United. States, the findings are of decided interest.

Particularly suggest iv® is the general agreement imeng them that the fabrics

involved in ignited clothing accidents are usually not of an uncs®»oftXy

flammable type. Such accident* appear t® result primarily from carelessmssi

or ignorance and inexperience, and a reasonable tightening of the flawmability

requirements might have little effect <m th@ir incidence.

The other two areas of special interest concerned with the development of technical data on the testing and f icaticm of fabrics. Questions

have arisen regarding the test procedure of Co^ssercial Standard 191-53 (the

primary basis for definition of hazardous flammability in the law), and

furthermore., it has been suggested that the more recent National Fire

Protection Association. Standard 702 might be & better basis for the law than

CSX91-53. First, therefore, an experimental study of the test method of

CS 191-53 was required to determine the importance of possible variations in

interpretation and equipment among different laboratories, and the need for

more precise definition of the standard. Then, in addition, a comparison of

the classification of representative current fabrics under CS19.1-53 with

their classification under NFPA 702 was desirable as a basis for judging

which standard might provide the more suitable definition of hazardous

flammability. The present report deals with <s program of experimental work

on these two technical phases of the problem.

2. Study of the Test Procedure of CS 191-53

The extensive application of C5191-53 sine® enactment of the Federal law

has brought to light a number of technical questions and problems. On several

points, the description of the apparatus and procedure has proved insufficiently

explicit to avoid a certain amount of variation in interpretation and practice

among different laboratories. In addition, the incomplete definition has

permitted modifications (apparently minor, but still possibly significant) of

the test equipment by the manufacturer. Although these variations have been

the source of considerable concern, their actual importance in affecting

the test results has been largely unknown.

With the help of copreents and suggestions from the organizations most concerned in the practical application of CSlfl-53, the test procedure was critically analyzed to determine those points where practice among laboratories

differed or a modification of procedure was proposed. The effect on the test

results produced by the variations noted or suggested at these points was then

determined experimentally for 9 representative group of fabrics. From this information, the importance of a given variable and the need for more precise

definition of the standard could be Judged

.
3

Six areas of possibly significant variation were noted, some with

several degrees of difference to be investigated, and this, extended to a number of fabrics, suggested a formidable amount of testing. Hence, to

avoid excessively prolonged and unnecessary experimentation, a program

of factorial experiments was designed for the project. After some preliminary trials to study the characteristics of the problem and determine the

number of repetitive specimens required, a general plan was adopted for

the several sets of tests carried out. For the most part, each set comprised three series of tests (using three different fabrics) in which the

same four variables in the test procedure were compared at the same two

levels of difference. Duplicate specimens were tested in each instance so that such a set of tests required 32 specimens of each fabric, with each

comparison based on the averages of 16 determinations. While the plan was

adjusted in some instances to study more than two levels of a variable at

one time or develop a point of particular interest, care was taken to maintain

a meaningful number of determinations in each comparison. In all, twenty-two

series of comparisons were carried out, and eleven different fabrics were

included, although several of the fabrics were used in only one series of

tests

.

The results of the twenty-two series of comparisons are shown in Table 1.

The mean burning time for all the specimens in the series (usually 32) is

given in the fourth column. The subsequent columns show the spread between

the average burning times (usually of 16 specimens) obtained between the

first and second of the indicated two levels of the particular variable listed

in the column heading. Thus, referring to Silk I, in a series of tests for

which the mean burning time was 3.32 sec,, the average burning time for the

specimens ignited on the surface was 0.17 sec. longer than that for the

specimens ignited on the edge (that is, 3.405 sec. - 3.235 sec.), and the

average burning time for the specimens with the thread 1/8 in. above the

fabric was 0.26 sec. longer than that for the specimens with the thread

3/8 in. above the fabric (that is, 3.45 sec. - 3.19 sec.). Differences which

proved to be significant under statistical analysis at the 95% confidence

level, are indicated by an asterisk.

Brief discussions of the six variables studied are given below, outlining

the sources and extent of variation experienced, the experimental approach

followed, and the findings developed:

1. Oven drying..

The commercial standard stipulates that the specimens shall be dried

in an oven for 30 minutes at 221 °F (105 °C) . The type of oven is not

specified and ovens differ widely in the time required to regain the specified temperature after introduction of a set of specimens. Hence, the

total time for which specimens may be held at a considerably elevated

temperature is highly variable, and the question of the possible effect

of this variable on the test results has been raised.
4

Tests were carried out using an oven equipped with forced air

circulation, which regained the specified temperature within two or

three minutes after introduction of a set of specimens. The effects

of holding specimens in the oven for 10, 15, 20, 30, and 60 minutes

were studied. No significant effect from variations over that range

was observed.

2, Desiccator cooling.

The standard requires that, upon removal from the oven, the

specimens be "placed over anhydrous calcium chloride in a desiccator

until cool, but for not less than 15 minutes." No maximum time limit

is imposed. The rate of cooling depends on the number of specimens

stacked in the desiccator, as well as on ambient conditions, and the

definition of "cool" will vary with different operators. Hence,

specimens may be left in the desiccator for periods ranging from

15 minutes to several hours.

In studying the effect of this variable on the test results,

desiccator times of 0, 15, 30, and 60 minutes were used. The

specimens tested with no time in the desiccator were removed individually

from the oven and tested immediately. Silica gel was substituted as a more effective and dependable desiccant than anhydrous calcium chloride.

The period of cooling in the desiccator proved unimportant after the

first 30 minutes, although the specimen holders were still warm at this

time. This suggests that the time required for the desiccant to absorb

the moisture introduced by change of air, is the critical factor in the

desiccator time rather than the temperature of the specimens and holders.

This view is supported by continuous humidity records obtained from a humidity sensor hung in the top of the desiccator, which showed that the

humidity in the closed desiccator closely approached its equilibrium level

in about 10-15 minutes, while it required more than an hour for the

holders and specimens to cool to room temperature.

3. Thread height

.

The thread guides on the specimen holder, which determine the

position of the stop cord over the specimen, are not precisely

described in the standard and have been subject to modifications which

resulted in differing heights of the thread above the fabric surface.

Specimen holders of both types are in use and the effect of thread

height on the test results is therefore of decided interest,

A set of specimen holders was prepared with guides which permitted

threading the stop cord at various selected heights ranging from 1/8

to 3/4 in. above the specimen surface. Primarily, however, attention

was centered on a comparison of the 1/8 in. and 3/8 in. heights, the

two heights appearing in commercially distributed holders.
5

The results in Table 1 indicate that reducing the space between

the thread and the fabric surface tends to increase the burning time.

The important point, however, is that the thread height has a significant effect on the test results and should, therefore, be standardized

and specified.

4. Flame length.

Although the length of the igniting flame is specified in the

standard, the measurement of its length depends to some extent on

the operator judgment and is slightly variable. In addition, the

flame length is sensitive to small changes in fuel pressure and some

laboratories reported difficulty in maintaining proper adjustment.

Hence, information on how critical a factor the flame length might be

appeared important.

The standard stipulates a flame length of 5/8 in. For the

comparative study, flame lengths 1/2, 5/8, and 3/4 inches were used.

The comparisons suggest that the flame length is critical chiefly

as it affects the distance between the flame and the fabric, not

with respect to heat output. Thus, significant differences occurred

only with the shorter flame length where the tip of the flame was

slightly farther from the fabric.

5. Taping of specimen.

Some lightweight fabrics are so thin that the smooth metal of

the specimen holders (which may also become slightly warped) fails to

grip the material. This permits the exposed area of the specimen to

sag slightly farther from the igniting flame in the case of soft, limp

materials t and fabrics which shrink and curl decidedly in a flame

tend to draw out of the specimen holder as they burn. To prevent such

behavior, the practice of securing the specimens of very thin materials

to the holder by means of an adhesive tape has been suggested. Taping

is sometimes used also, to hold in a reasonably smooth, flat position,

the badly wrinkled specimens of materials which might be altered by

pressing.

Tests were made on both taped and non-taped specimens of the same material. The taped specimens were secured to the back section of the

specimen holder by means of four short strips of masking, tape, one near

the top and one near the bottom of each side of the specimen. Although,

for the most part, taping the specimens to the holder appeared to give

slightly shorter burning times, the difference did not prove significant

in any instance. This indicates that taping should be an acceptable pro

cedure in situations where it would facilitate positioning the specimen.
6

6. Type of ignition.

Among suggestions for change in the Federal law has been the

proposal that C S 1 9 1 - 53 be replaced by National Fire Protection

Association Standard 702 as the basis for defining hazardous

flammability. The two standards employ basically the same test

equipment but differ in test procedure , the most notable difference

being the method of igniting the specimen,. In CS191-53, the igniting

flame is applied to the surface of the specimen for one second, while

in NFPA 702, it is applied to the edge of the specimen until ignition

has occurred o This variation In ignition procedure was included in

the study.

The burning times for surface ignition were significantly longer

than those for edge ignition, as would be expected. The only materials

which failed to show this effect were those subject to a rapid surface

flash initiated by the first touch of a flame.

In addition to the difference in procedures outlines above, the comments

included several suggestions for modification of the apparatus. Most frequently mentioned was a possible advantage from the substitution of an electrical timing system for the mechanically-operated stopwatch described in the

standard. Some operators felt that an electrical system would provide more

precise measurement and be more convenient and dependable in operation as well.

To develop experience and information on the question, an electric timer was

incorporated in the apparatus in such a way that both it and the stopwatch

were activated by the same devices and provided simultaneous records.

The data obtained are presented graphically in Figure 1, where the

difference between the reading of the electric timer and that of the stopwatch,

for individual specimens was plotted against the time as recorded electrically*

A consistent bias toward one device or the other would result in a preponderance of points either above or below the zero line on the vertical axis.

Such an effect is evident at times less than 1,0 second, where most of the

differences were negative indicating that the stopwatch gave consistently

higher readings in that area. This resulted from the fact that the mechanical

system could not register times less than the duration of flame application

which was set at 1,0 second. Otherwise, the data indicate no consistent bias,

particularly at the burning times of primary interest, At burning times

longer than 9 or 10 seconds slight trends may be suggested, but, with most

of the differences less than +0.1 second, they are scarcely significant.

Hence, it would appear that either timing method may be used satisfactorily

if proper adjustment is maintained, the resolution with the electric timer

is much finer, of course, but the need for this precision is questionable.
7

Another point on which some question was raised involved the positioning of the specimen in the specimen holder. The usual practice of most

operators appears to have been to place the lower end of the 6- in. specimen

even with the lower end of the back plate of the specimen holder. Inserted

thus, the igniting flame should impinge on the surface of the material at a point 1/2 in. from the lower end of the specimen. However, this 1/2 in.

spacing (which may be further reduced by only slight deviations in flame or specimen adjustment) is small enough that fabrics subject to severe shrinkage

in a flame may draw the edge up to produce essentially edge ignition.

Throughout the present study, the specimens were positioned about 1/8 in.

lower in the holders in order to slightly increase the distance between

the point of flame impingement and the specimen edge. This was accomplished

by cutting the specimens 6-1/4 inches in length and positioning the upper

end even with the top of back plate.

One of the modifications which have developed in the apparatus since

the original design, appears in the rack which supports the specimen holder

during test. In the early machines, the metal support on which the bottom

of the specimen holder rests was a continuous bar running across the full

width of the rack. In the currently produced machines, However, the bar has

become discontinuous, supporting the specimen holder at the corners but

leaving the center open. While these arrangements are equally satisfactory

for support of the holder, the conditions of air flow around the bottom edge

of the fabric specimen will be affected by the presence or absence of the

partial obstruction of the bar across the center of the rack. Although the

effect of this modification was not studied extensively, sufficient comparison was made to show that it does influence the burning times of some

fabrics, and should be standardized in all machines.

3. Comparative Classification Under CS191-53 and NFPA 702

To develop information on the comparative classification of current

fabrics by the two standards CS191-53 and NFPA 7C2 , about fifty materials

were purchased at various stores on the ordinary retail market. Inasmuch

as proposals have been made to extend coverage of the Federal law to bedding

materials, representative blanket and other bedding fabrics were included,

along with a wide range of clothing fabrics.

The test method itself is very similar for the two standards. They

employ the same apparatus and the procedures differ primarily in the manner

of igniting the specimens of smooth- surfaced fabrics (without nap, pile,

or other type of raised-fiber surface). In CS191-53, the igniting flame is

applied to the surface of the specimen for one second only, whereas in NFPA

702, the igniting flame is applied to the edge of the specimen as long as necessary to achieve ignition. Both standards require the one-second sur- face application of the igniting flame for fabrics with a raised-fiber

surface

.
8

; .y

'

' , .1 i

'

. • . The igniting procedure was the only significant difference in the

methods used in developing the comparative classification of fabrics. Other

parts of the test method were standardized on the basis of the study reported

above. The oven conditioning of 30 minutes at 105 °C was retained and a uniform period of 30 minutes in. the desiccator was adopted. Specimen holders

with a bent-pin type of thread guides providing a uniform thread height of

3/8 in. across the specimen were used. This was facilitated by the installation of a new thread guide in the cabinet above the spool. The practice of

positioning the specimen 1/8 in. lower in the holder was continued. The support rack on which the specimen holder rested during the test, was used with a discontinuous support bar as provided in currently-produced machines. The

flame length was maintained at 5/8 in. and checked frequently, with particular

care to avoid variations toward a shorter length. Use of the electric timer

concurrently with the mechanical stopwatch was continued.

Because of the number and diversity of fabrics involved, the program

offered an excellent opportunity to develop information on the heat produced by

the burning of different fabrics, as well as their comparative classification.

Flame intensity is commonly recognized as an important element in hazardous

flammability, but it has proved difficult to gage, and it appeared that data

on the heat output of the various materials, might be helpful. As a heat sensor,

a copper plate 4 in. square, 0.022 in. thick, and weighing 51.5 grams, was

installed in the test cabinet above the upper end of the specimen. It was

hung in a horizontal position 1/4 in. below the top of the cabinet and did

not alter the test conditions within the cabinet. A #28 gage (.0126 in.)

chrome 1-alumel thermocouple attached to the plate permitted recording a continuous trace of the plate temperature. From the known characterest ics

of the plate and its increase in temperature, the- heat absorbed by the plate

may be calculated, and for comparative purposes, it may serve as a measure

of heat output of the specimen. In comparing data obtained with the same

sensor, however, the calculation is unnecessary, since the increase in temperature is the only variable among the determinations. Assuming linearity

over the temperature ranges involved, millivolt changes in the thermocouple

signal will serve to represent changes in the plate temperature.

The fabrics included in the comparison are listed in Table 2 together

with the data obtained using the two different ignition procedures. The

values shown for burning time and millivolt change are, in most instances,

the average for six determinations. To obtain heat output readings for those

materials which did not ignite during the one-second surface application " . of the igniting flame, ignition was forced by manually continuing the flame

application until ignition occurred. Most of the fabrics with a raised-fiber

surface would not ordinarily have been tested differently or have different

values under the two standards, but in the interest of developing as much

comparative information as possible, the two types of ignition were continued

through that class of fabrics also. Hence, the data shown under NFPA 702

for raised-surface fabrics were obtained with edge ignition just as those

for the smooth-surfaced fabrics.
9

Predictably, the burning times obtained with edge ignition were, in

most cases, shorter than those obtained with surface ignition. On

brushed surface materials which showed a rapid surface flash, however, it

made no difference how the flame was applied, and for lighweight materials

which ignited quickly, the effect was generally small. On the basis of

the present respective definitions of hazardous flammability, NFPA 702 and

the Federal law provided almost identical classifications of the materials

studied. One borderline silk was recorded as failing the Federal law

definition by a slight margin while it just barely passed the NFPA 702

definition, but the variation in a fabric itself is such that a borderline

material may fall on either side of a precise defining line in repeated

trials. The results of this study indicate, therefore, that the classification of fabrics as hazardously flammable would be changed little, if any,

by making NFPA 702 the basis of the Federal law.

In addition to the classification for fabrics, the NFPA standard

provides requirements for non-textile articles of wearing apparel (not

covered in CS191-53) and this has been cited as a special recommendation for

its inclusion in the Federal law. There is a general concensus that such

items should be subject to control, but the developement of a suitable method

of testing articles of such varied size, shape, and composition has proved

extremely difficult. Several suggestions have been made for possible test

procedures, besides that described in NFPA 702, and some work with various

types of masks and other costume items has been carried out. Definite

recommendations have not yet been developed, however, and continued study

of the problem is planned.

4. Discussion of Data on Heat Output

A graphical presentation appeared appropriate for consideration of the

data obtained on the heat produced by the burning specimens. Figure 2 shows

the average ’neat sensor output plotted against the average burning time,

using the results obtained with the surface ignition procedure of CS191-53.

For the materials which did not ignite from the ususal one-second flame

application, the data resulting from ignition forced by continued application

of the flame were used. To help in study and analysis of the data, broad

groupings of the fabrics are indicated by identifying symbols.

Although a number of varying factors (special finishes, novelty weaves,

quilted h ruinations, etc.) entered into the results, some general indications

may be reted. Thus, under the particular conditions of the test, materials

entirely of Dacron or of silk appeared relatively low in heat output. There

is also a general indication that, among fabrics without a raised-fiber

surface, acetates or blends predominantly acetate, tended to produce somewhat

more heat than cottons and rayons which showed a similar rate of flame spread

Among the fabrics with raised-fiber surface, those with acrylic brushed or pile surface did not show the rapid flash of the cottons and rayons although

their heat output was comparable or greater.
10

A study of the graph suggests that, should it be considered desirable,

heat measurements of this type could serve as part of the definition of

hazardous flammability. The ratio of heat output to burning time could be

used as an added criterion, with the requirement that values for the ratio

higher than those represented by a selected line (such as the dashed line

shown) would class a material as hazardously flammable. This would include

the factor of flame intensity in the definition on a broader basis than at

present, and would somewhat strengthen the requirements for acceptability.

In the case of brushed cottons and rayons, for example, a slightly lighter

brushing, to shift the burning time to around 4.5 seconds, would no longer

be enough to achieve acceptability. If desired, the criterion could be

extended on down to zero time for fabrics with a raised-fiber surface,

providing a requirement perhaps a little more severe than the present criterion

of base fabric ignition.

In Figure 3, the heat sensor output is plotted against the fabric weight.

The generally linear relation suggests that fabric weight might reasonably

represent the heat output, and hence that actual heat determinations might

be unnecessary. In Figure 4, the fabric weight (rather than heat sensor

output) has been plotted against burning time. It is evident that a requirement limiting the ratio of fabric weight over burning time to values no

greater than those represented by the dashed line in Figure 4 would provide

almost the same differentiation of the fabrics studied as that provided by a criterion based on the heat sensor measurements shown by the dashed line of

Figure 2, For fabrics which show a "timed-surface flash" that fails to

ignite the base fabric there is, of course, little relation between the heat

output of the surface flash and the weight of the whole fabric. For this

group, therefore, the fabric weight/burning time ratio could not properly

represent the heat output /burning time ratio and, unless actual heat measurements were made, the criterion would not suitably replace that of base fabric . ignition. -

'

In addition to the determinations in the inclined flammability tester,

heat measurements were made on about 30 of the fabrics by another, method

which had been used in previous work [2]. This method used equipment

similar to a British design developed for the measurement of heat supplied

to an adjacent surface by a burning fabric. A specimen 30 inches long and

- inches wide was suspended vertically, 1/2 inch from an asbestos millboardback panel and held in place by six wire cross-lacings about 4 inches apart.

I he specimen was ignited across the lower end and allowed to burn freely,

Cylindrical copper plugs, 1/2 inch in diameter and with thermocouples attached

to the back, were set flush in the millboard panel at several heights and the

heat dosage received by a given plug could be calculated from its known

characteristics and its recorded temperature rise. For a general comparison

with heat measurements obtained in the CS191-53 tests, however, the change

in the electrical output of the thermocouple itself is sufficient, and, in

Figure 5, the millivolt signal recorded in the inclined method was plotted
11

against that recorded by a copper sensor plug located about 14 inches

below the top of the specimen. A close correlation could not be

expected since the two methods involve different types of exposure under

different conditions, but the relation between them appears to be roughly

linear. This tends to support to some extent the validity of both methods

as acceptable means of gaging a basic characteristic of the fabric.

5 . Summary

In the interest of effective public protection, a review of the operation

of the Flammable Fabrics Act and the adequacy of textile flammability

standards was requested by the Secretary of Commerce. While facilities for

collecting information on actual accident experience are not presently

available, technical phases of the review have been carried out. An experimental study of the test procedure of CS191-53 was made to determine the

importance of certain variations in practice and interpretation among

laboratories and the effect of various proposed modifications. On the

basis of this study, a standard procedure was selected for continued work

with the method. Varying only the manner of ignition, to conform to CS191-53

and NFPA Standard 702, respectively, comparative data were developed by the

two methods on current clothing and bedding fabrics. The NFPA Standard 702

provided almost the same classification of the approximately fifty fabrics

studied as that of the Federal law, on the basis of the present respective

definitions of hazardous flammability. In conjunction with developmnet of

the comparative classification of the fabrics, measurements of the comparative heat output were made which suggested a possibly useful criterion of

flame intensity.

6. References

[1] Lawson, D. I., "Fire Accidents - The Contribution of Some Textiles,"

Research Vol 11 (1958); pp. 126-133.

[2] Sandholzer, M. W., "Effect of Fiber Composition on Textile Flammability,"

NBS Technical Report No. 7339. (Sept 1961)

A T5 4J 00 H

0) Oucn

rn csj m m

M >s

T3 e c O CO <u 00 uo o u o o o o O O C-) 00 CO O O O O O O O o o o o o o o o O O' O' O'

—• o o o

Results

significant

ata

confidence

level

of

95%

or

greater
Table 2. Comparative Data on Fabric Materials

Fabric Description I CS191-53 (Surface Ignition) |NFPA702(edge Ignition)

Identifying Fiber Burning Time Heat j Burning j Heat Designation Content Weight 1 sec . Exposure Forced Ignition Output Time Output

oz/yc? ^

' sec sec mv ! sec mv

Fabrics with raised- fiber surface ;

Flannelette Cotton 3.7 DNI

r

1 16.8 0.662 7.0 0.627

Receiving

Blanket I Cotton 5.7 1.1 0.838 1.1 0.851

Receiving

Blanket II Cotton 6.0 0.9 0. 730 0.9 0.751

Bed Rayon , 94%

Blanket I Nylon, 6% 5.8 0.9 0.719 0.9 0.752

Bed Rayon , 74%

Blanket II Cotton, 20%

Nylon, 6%

6.3 0.9 0.898 0.9 0.956

Torch Sweater Rayon 9.0 0.9 1.269 0.9 1.405

Pile Rayon .pile 13.4 1.8 0.228 20.6 1.433 Fabric I Cotton back (TSF)

Pile Acrylic pile 8.4 16.4 1.459 13.0 1.489

Fabric II cotton back

Pile Acrvlic(0 rlon)

Fabric III pile 9.2 19.6 1.777 14.1 1.690

Cotton back

(0 Crib blanket Acrylic 9.7 27.4 22.7 2.278 21.0 2.390

Tufted I Cotton 7.6 2.1 1.029 2.5 0.999

Tufted II Cotton 9.4 4.7 1.296 7.2 1.263

Tufted III Cotton 16.3 7.0 1.822 7.0 1.787

Fabrics without raised-rf iber surface

Chiffon Rayon 1.0 2.9 0.214 2.4 0.231

Organdy Cotton 1.5 3.9 0.316 3.1 0.328

Batiste Cotton 1.8 7.8 0.342 3,6 0,334

Novelty I Rayon 3.3 8.6 0.614 5.7 0.642

Shantessa

Cotton 3.9 DNI 20.5 0.492 5.8 0.595

Print

Percale sheet Cotton 3.9 DNI 20.6 0.626 6.4 0.613

Byrd cloth Cotton 4.8 DNI 12.0 0.806 7.8 0.806

Stretch Cotton, 50%

Poplin Zantre

1

6.2 DNI 24,4 0 . 980 9.4 1,011

Rayon, 50%

Bengaline 6.5 DNI 26.1 0.858 11.1 0.927

Stretch duck Cotton 6.7 DNI 28.9 1.070 10.9 1.098

Boucle Rayon, 62%

Acetate ,38% 7.3 DNI 31.0 1.065 11.2 1.130

Monks Cloth Cotton 8.1 DNI 24.2 1.252 12.5 1.255

Army sateen Cotton 8.6 DNI 37.8 1.333 16.0 1.310

Novelty II Rayon, 94%

Silk, 6%

9.0 DNI 40.6 1.019 13.3 1.191

Raincoat Cotton warp

Acetate fill

6.3 DNI 22.6 1.072 10.5 1.038

Quilted pad Cotton 9.6 DNI 26.8 1.380 16.0 1.356

Silk I Silk 0.6 3.2 0.102 3.0 0. 102 Silk II Silk 0.7 3.6 0.115 3.5 0,111

Silk III Silk 1.3 6.4 0. 176 6.2 0. 189
Table 2. Comparative Data on Fabric Materials (concluded)

Fabric Description CS191-53 (Surface Ignition) NFPA702(Edge Ignition)

Identifying Fiber Burning Time Heat Burning Heat Designation Content Weight j 1 sec. Exposure Forced Ignition Output Time Output

oz/ydf

i sec sec mv sec mv

Fabrics without

1 raised-fiber surface (cone luded)

Novelty III Acetate 1.7 3.9 0.347 j

1 3.6 0.376

Sheer Dacron 2.0 13.2 0.219 j 12.7 0.202

Print I Acetate, 607, Cotton, 407, 2.4 6.5 0.513 4.5 0.487

Print II Dacron, 65%

Cotton, 35%

2.6 DNI 8.9 0.459 5.1 0.454

Lining fabric Acetate 2.8 5.2 0.524 5.3 0.510

Dotted Swiss Dacron, 65%

Cotton, 357. 2.8 DNI 9.9 0.502 5.6 0.512

Lined Lace I

( lock- lined) Acetate lining

Cotton lace

5.1 8.7 1.044 7.1 1.030

Lined Lace II Acetate lining

lace (wool, 50%

(rayon, 50%

7.1 DNI 15.9 1.368 12.1 1.497

Novelty IV Rayon, 607, Linen, 25%

Wool, 15%

7.9 DNI 21.6 1.315 13.0 1.386

Taffeta Acetate 3.5 6.2 0.570 5.4 0.536 Net Dacron 0.8 5 . 9

(21 0.074 8 .

6

(2) 0.050

Quilted robe I (face) Acetate cover

and lining,

polyester pad

5.9 14.1 0.888 12.5 0.829

Quilted robe I (back) II 5.9 14.8 0.971 9,9 0.945

Quilted robe II (face) Acetate cover

and lining,

polyester pad

6.8 18.8 1.110 11.9 0.937

Quilted robe II (back) II 6.8 18 . 9 W 15.4 1.112 10.7 1.024

Quilted robe III

(face)

Acetate cover

and lining, acetate pad

5.1 DNI 11.6 0.825 9.3 0.791

Quilted robe III

(back) II 5.1 15. 0^ 9.6 0.722 8.7 0.639

DNI - did not ignite during the 1-sec. flame exposure

TSF - timed surface flash which burned the thread but did not ignite the base fabric

(1) - value based on the 3 or 4 specimens which ignited; the remaining 2 or 3 specimens required forced

ignition with an average time as shown.

(2) - flame travel erratic and usually self-extinguished; surface ignition values are averages for 5 out

of 12 specimens tested, edge ignition values are averages for 2 out of 12 specimens tested.

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MILLIVOLTS

FIGURE 3. RELATION OF HEAT OUTPUT TO FABRIC WEIGHT

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<8 RAYON PILE SHOWING TSF (TIMED SURFACE FLASH)

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.1
Appendix

It was evident that some of the variations which had developed in the

application of CS191-53 resulted from changes in the manufacture of the

equipment, which influenced the procedure although they did not violate

the specifications of the standard. To avoid further such inadvertent

modifications, it is recommended that the drawings be adopted as part of

the commercial standard, or as a subsidiary requirement of the Secretary

of Commerce, and that all future revisions should be subject to approval

by the Secretary of Commerce. Before such adoption, however, it is

recommended that the following clarifications and additions be incorporated in the drawings:

1. At the base of specimen rack © Drwg D453, change 3/8 dimension

on 45° line to 5/16.

2. Revise thread guide © in right elevation, Drwg D453, of specimenholder assembly. There should be a tolerance on height of guides

above top plate, perhaps ± 0.01 in.

3. Add additional thread guide, (lO) of D453, to cabinet, D450,

above thread spdol, at a point 8-1/4" above floor and 5-1/4"

from back. Include dimensioned positions for all thread guides.

4. Make counterweight © on Drwg D452 of brass or increase the

size of steel weight to 1" dia x 1-1/2" long. (The specified

dimensions in steel do not provide sufficient weight)

.

5. On Drwg D454, part 25, dimension of weight diameter is indicated

as changed to 3/4 in. Current production, however, involves

5/8 in. dia weight as was used in our tests. This weighs about

33 gms . The weight should be specified.

6. The drawings should include dimensions of the flame length gage

and the sheet metal specimen shim and block.
.

*"

v • ; 1