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NBSIR 78-1497 I AlllDM E37STM

A Preliminary Study of the Fire

Safety of Thermal Insulation

for Use in Attics or Enclosed

Spaces in Residential Housing

AlllDM E37S^

Daniel Gross

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

July 1978

— QQ —J.S. DEPARTMENT OF COMMERCE

100 MATIONAL BUREAU OF STANDARDS

.U56

78-1497

Bureau of Standards APR 17 1979

\ H.'

NBSIR 78-1497

A PRELIMINARY STUDY OF THE FIRE

SAFETY OF THERMAL INSULATION

FOR USE IN ATTICS OR ENCLOSED

SPACES IN RESIDENTIAL HOUSING

Daniel Gross

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

July 1978

P- I r.4/

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch. Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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CONTENTS

Page

LIST OF FIGURES iv

LIST OF TABLES iv

Abstract 1

1. INTRODUCTION 1

2. FIRE STATISTICS 3

3. RATIONALE AND PROBLEM OUTLINE 4

4. CURRENT TEST METHODS 5 4.1 Steiner Tunnel Test — ASTM E-84 5 4.2 Floor Mounted Tunnel Test 6 4.3 "Two Foot" Tunnel Test 6 4.4 Noncombustibility Test — ASTM E-136 6 4.5 Loss of Ignition Test (Sec. 4.4.6 of HH-I-1030A) 7

5. ATTIC FLOOR RADIANT PANEL TEST 7 5.1 Attic Floor Radiant Panel Test 7 5.2 Cigarette Smoldering Test 10

5.3 Mockup Flame Spread Tests 11

5.4 Mockup Smoldering Tests 14

6. SUMMARY AND CONCLUSIONS 16

7. ACKNOWLEDGMENTS 17

8. REFERENCES 18

APPENDIX A. FIRE INCIDENT DATA ON THERMAL INSULA.TION 19

APPENDIX B. STANDARD METHOD OF TEST FOR CRITICAL RADIANT FLUX OF

EXPOSED ATTIC FLOOR INSULATION USING A

RADIANT HEAT ENERGY SOURCE 22

ANNEX A PROCEDURE FOR CALIBRZ^TION OF RADIATION INSTRUMENTATION . . 29

APPENDIX C. STANDARD METHOD OF TEST FOR SMOLDERING COMBUSTION

CHARACTERISTICS OF MATERIALS USED FOR THERMAL

INSULATION 40

iii
LIST OF FIGURES

Page

Figure Bl. Radiant panel test chamber 30

Figure B2. Horizontally-mounted after floor insulation specimen ... 31

Figure B3. Flooring radiant panel tester schematic — side elevation. 32

Figure B4. Flooring radiant panel tester schematic — low flux end,

elevation 33

Figure B5. Dummy specimen holder 34

Figure B6 . Specimen tray 35

Figure B7. Flux profile data log format 36

Figure B8. Standard radiant heat energy flux profile 37

Figure B9. Specimen tray mounting position 38

Figure BIO. Insulation radiant panel test data log format 39

LIST OF TABLES

Table 1. Test materials 8 Table 2. Attic floor radiant panel test results . . 9 Table 3. Smoldering combustion test results 12

Table 4. Mockup smoldering combustion tests 15

Table Al. Distribution of NFIRS insulation by type of material

ignited 21

Table A2 . Distribution of NFIRS insulation incidents by form of

heat of ignition 21

iv

>

I
A PRELIMINARY STUDY OF THE FIRE SAFETY OF THEWIAL INSULATION

FOR USE IN ATTICS OR ENCLOSED SPACES IN RESIDENTIAL HOUSING

Daniel Gross

Abstract

An evaluation was made of the appropriateness of the

flammability requirements in Federal specifications for

loose-fill cellulosic and mineral fiber insulation and

mineral fiber batts and blankets. This included an analysis of currently used standard test methods for measuring

insulation flammability or combustibility and their principle limitations. To provide for more meaningful evaluations,

a review was made of fire statistics and of likely fire

occurrences, particularly for retrofit insulation in attic

and enclosed spaces of residential buildings. A series of

laboratory tests was conducted using an attic floor radiant

panel test and a cigarette smoldering test to simulate

flaming and smoldering exposures. Mockup tests on attic

floor sections were conducted to validate the extent of

flame spread on attic insulation and the initiation of

smoldering ignition from covered recessed light fixtures.

Based on these tests, changes were recommended to Federal

Specifications HH-I-515C, HH-I-521E and HH-I-1030A.

Key words: Attics; Federal specifications; fire test;

flame spread; loose-fill; mineral fiber; residences;

smoldering; thermal insulation.

1 . INTRODUCTION

With the current increased use of thermal insulation, a number of questions

about fire safety have been raised. This has been due to reported fire incidents involving thermal insulation and an awareness of the possible consequences

of using increasing quantities of insulation in attics, walls, crawl spaces

and particularly around heat sources such as heaters and electrical devices.

This concern was highlighted at the August 22, 1977, public meeting called by

the Consumer Product Safety Commission (CPSC) in response to a petition from

the Attorney General's Office of Denver, Colorado, regarding the potential

1
fire hazards of certain types of thermal insulation.

At that meeting, there were requests that the Consumer Product Safety

Commission use existing Federal specifications as a basis for nationwide

mandatory or voluntary standards for flammability of insulation. Federal

specifications for construction materials are generally used (a) for Government purchase of materials for use in Federal buildings and (b) by others in

private or in federally supported 'housing. Consideration is also being given

to the use of Federal specifications for acceptance of insulation materials in

the event of enactment of tax credit legislation.

The position expressed by a number of speakers at the CPSC meeting encom- passed the following thought: "If it's Government policy to conserve energy,

it should be Government policy to insure use of safe products." The discussion

implied a thesis that the addition of insulation should not increase the

normal and expected level of fire risk to the resident.

The methods used to install insulation are extremely important from the

standpoint of fire. Good installation practice, e.g., as specified in the

National Electrical Code [1]^, and the Manual on Clearance for Heat-Producing

Appliances [2], would provide physical separations between heat appliances,

electrical fixtures, etc. and the thermal insulation. From a realistic standpoint, however, it can be anticipated that batt, blanket, and loose-fill

insulation will be placed in contact with such appliances and fixtures, particularly with do-it-yourself and retrofit insulation projects in single family

homes. Indeed, there may be no practical way to isolate a recessed light

fixture which is located near the eave of an attic.

With the above philosophy in mind, the National Bureau of Standards (NBS)

Center for Fire Research (CFR) evaluation presented here was focused primarily

on the appropriateness of the flammability requirements of the three Federal

specifications listed below. Although limited to the flammability portions of

these three specifications, it is felt that the conclusions of this study

would be applicable to other types of insulation used in a similar manner.

Numbers in brackets refer to the literature references listed at the end

of this paper.

2
The three specifications reviewed are:

HH-I-515C Insulation Thermal (Loose Fill for Pneumatic or Poured Application) : Cellulosic VJood Fiber

HH-I-521E Insulation Blankets, Thermal (Mineral Fiber, for

Ambient Temperatures)

HH-I-1030A Insulation, Thermal (Mineral Fiber, for Pneumatic

2 or Poured Application)

The requirements of the HH-I-515C and HH-I-521E specifications are based

on a flame spread classification of 25 (or 50) and a smoke developed classification of 50 according to a prescribed standard flame spread test [3], while

the HH-I-1030A specification provides for classification in terms of a maximum

weight loss on ignition of either 1 percent or 12 percent.

The evaluation was based on a review of fire statistics, a statement of

the perceived problem, a review of current test methods, and the performance

of the insulation in laboratory fire testing. This report provides a brief

summary of the more important information, findings and conclusions, including

suggested changes to the specifications.

2. FIRE STATISTICS

Extensive data on the contribution of thermal insulation to fires are not

available. We have reports of fire incidents in Denver, in Oklahoma City, in

the state of Michigan, and in other locations. For example, the Departments

of Public Safety and Public Health in Michigan have assembled data on fire

incidents involving "paper insulation" as the first material ignited. There were 158 cases reported in 1975 and 1976 and 49 cases through part of 1977.

Between 45 and 55 percent of all these cases involved treated paper insulation.

The Oklahoma City Fire Department listed 24 cases in an 8-month period, involving recessed light and heater fixtures and flue and vent pipes covered

with cellulose and mineral wool insulation.

On a nationwide basis fire data are collected in the Field Incident Data

Organization (FIDO) system of the National Fire Protection Association and the

National Fire Incident Reporting System (NFIRS) data system of the National

Fire Prevention and Control Administration. These data are summarized in

appendix A. The NFIRS data total 496 incidents in two states.

Available from Business Service Centers at the General Services Administration

Regional Offices in Boston; New York; Philadelphia; Washington, D.C.; Atlanta;

Chicago; Kansas City, Mo; Fort Worth; Houston; Denver; San Francisco;

Los Angeles; and Seattle, Wa.

3
These data files code the first material ignited only and not the materials

which contribute to fire spread. When thermal insulation was the first material

ignited, its composition was generally cellulosic. Noncellulosic insulation

materials accounted for only about 25 percent of the fires classified by

specified materials. The intent of this review of fire incidence statistics was not to measure or estimate the magnitude of the problem, inasmuch as the

data are uneven in quality, are not statistically representative, and do not

reflect the potential future problems associated with retrofit insulation.

They are useful, however, in providing an indication of possible patterns of

ignition types and sources.

The two most commonly cited ignition sources were "electrical equipment,

including short circuits," and "propane torches." These data illustrate the

two most significant potential fire scenarios for insulation:

(1) a covered electrical (or heating) device, or a wiring hot spot,

may cause smoldering ignition of insulation or ignition of a flammable vapor barrier;

(2) open flame from a plumber's torch, a match, or a spark from

an appliance may cause ignition of exposed insulation.

3. RATIONALE AND PROBLEM OUTLINE

A need exists for a meaningful standardized fire test for evaluating

attic insulation. The same test should be applicable to all types of insulation used for the same purpose.

Current specifications generally use a surface flame spread test. The

rationale for this is not completely clear but probably is based partly on the convenience of using the same standard ASTM E-84 Flame Spread Test [3]

,

which is referenced in most codes for interior wall and ceiling finish; and

partly because of a lack of a suitable standard test method for flaming and

smoldering ignition, even though ignition is always the first step in the

chain of events leading to a major fire.

The fire properties of a material which determine its potential contribution to the start or spread of fire and which may ultimately result in life

loss, injury, or property damage are, in estimated order of importance: (a)

heat contribution, (b) ignitability (flaming or smoldering), (c) surface flame

spread, (d) smoke production, and (e) toxic combustion products. In general,

these properties are sensitive to insulation density and to test configuration

since they are affected by the airflow patterns and the overall heat transfer.

Thermal insulation comes in several types and forms: boards, blocks,

sheets, blankets, batts, felts, loose fill, f oamed-in-place or prefoamed

sheets. Insulation may be fibrous, closed or open cell, or in composite form

4
to yield high thermal resistance; and it may be used in many places in many

types of buildings. For this study we were concerned mainly with its use in

the attics of residential dwellings.

In many applications, thermal insulation is left uncovered, where it may

be directly exposed to a potential flame or heat source. Typical examples

include insulation placed between the ceiling joists or roof rafters in an attic, in crawl spaces, in basement and utility spaces, or on walls or ceilings as a decorative finish. Alternately, thermal insulation may be enclosed

in stud wall spaces, in floor or ceiling spaces or in other wall or roof

cavities, where it is not likely to be exposed to flame sources, but could be

in contact with sources of heat and electricity. In addition, thermal insulation may be temporarily exposed, such as during construction or repair.

In order of priorities, the fire incidence patterns suggest the most

likely hazards are: (1) smoldering ignition of insulation in the attic;

(2) flame spread along the surface of attic insulation; and (3) ignition plus

flame spread along blanket insulation on the walls and ceilings in the basement area. Based on this, the primary emphasis of this evaluation was placed

on insulation used in attics.

4. CURRENT TEST METHODS

4.1 Steiner Tunnel Test — ASTM E-84

This test, which is used in Federal Specifications HH-I-515C and HH-I521E, utilizes a prescribed wire screen to retain loose fill insulation, and

steel rods to hold batts and blankets in a ceiling position. The specimen is

mounted on the ceiling of a long narrow tunnel and exposed to burner flames at one end, with a prescribed airflow. The flame spread classification (FSC) , or rating, is based on the observed extent and speed of flame travel within the

25-ft (7.62 m) long tunnel in comparison to asbestos-cement board (FSC = 0)

3 and red oak lumber (FSC = 100) . The testing laboratory may apply a "correction" to the test result in an effort to account for the presence of the wire screen. The correction is not

now a test requirement of ASTM E-84 and not all laboratories use it. Questions

and problems which arise in the use of this test method for insulation

materials include:

(1) Is the flame spread classification a reasonable comparison tool

for all densities and material forms', so that a classification

of 100 means the same for a low density cellulosic insulation

as for a dense solid wood?

3 This Standard uses values expressed in U.S. customary units. In this report,

U.S. customary units are used where specified and where commonly used.

5
(2) Does a classification of 25 apply equally to such materials?

(3) The test has been shown to be invalid for low density fireretardant treated plastic foams, in terms of measuring their

4 contribution to fire growth . Its applicability to and appropriateness for other low-density insulation materials may also

be seriously questioned.

(4) Is it valid to test a material in the ceiling of the tunnel

to represent its use on the attic floor, particularly when

we know that the flame spread phenomenon is different for

each position?

(5) Does the correction applied for the wire screen have any

validity in relation to the real performance of the insulation?

Finally, neither this test nor any of the other current test methods provides

for measurement of smoldering combustion characteristics.

4.2

Floor Mounted Tunnel Test

The inappropriate use of the tunnel test associated with testing a flooring material on the ceiling has been recognized by the Fire Research

Section, National Research Council, Ottawa, Canada. Based on their tests, a modification of the E-84 test for loose fill cellulosic insulation has been

adopted by the Canadian Standards Association [4]. It is also used for

carpeting and other floor coverings. No wire screen is needed to hold the

specimen in place. However, this test uses the same 5000 Btu per minute

(108 kW) burner with 4-1/2 foot (1.37 m) flame exposure and 240 fpm (73.2

m/min) induced draft within the narrow tunnel apparatus and there is a question

as to whether this is applicable to a reasonable fire scenario in an attic.

4.3

"Two Foot" Tunnel Test

This is not a standard fire test method. It is referenced in ASTM C739

[5] and is intended to serve as a low cost screening or quality control test

to examine the effects of high temperature and humidity conditioning on cellulosic loose fill insulation.

4.4

Noncombustibility Test — ASTM E-136 [6]

This is a pass/fail test, which does not provide a quantitative or numerical measure of combustibility. It is used in some building codes for defining

"noncombustible" materials for use in certain classes of buildings.

Parker, W. J., National Bureau of Standards, private communication.

6
4.5 Loss of Ignition Test (Sec. 4.4.6 of HH-I-1030A)

This is a pyrolysis and weighing test used for estimating organic content

In HH-I-1030A the exposure pyrolysis temperature is 800°F (427°C) , although

temperatures as high as 1652°F (900°C) are more commonly used in other specifications .

5. NBS LABORATORY TEST STUDIES

A number of insulation materials meeting the three referenced Federal

specifications were obtained from Government and commercial sources. In

addition, a few insulation materials which were not identified with any

particular specification were also obtained. The materials are listed

in table 1. This list was not intended to be extensive or complete and no chemical analyses or other tests were conducted. A fairly extensive review

and analysis of loose fill cellulosic insulation was recently published by

the Energy Research and Development Administration (ERDA) (now Department of

Energy) [7]

.

5.1 Attic Floor Radiant Panel Test

This test is essentially identical to Federal Test Method No. 372 [8]

and to NFPA Standard Test Method No. 253 used for flooring evaluation. The

conditions of this test simulate the configuration and the radiant heat

exposure which may be experienced by insulation laid on or between attic

floor joists, and subjected to a small open flame ignition.

The proposed test, described in appendix B, measures the imposed heat

flux at which a fire will no longer propagate flame on the surface of the

insulation under the test condition. This is called the critical radiant flux

and is a quantitative measure of the ease with which flame propagation may

occur on the surface of the test material in the given configuration when

subjected to radiation from a heated overhead surface, in this case the attic

roof

.

The results with the Radiant Panel Test are summarized in table 2.

Clearly there is a wide range in test results ranging from no ignition and no flame propagation to extensive flame propagation along the full length of the one meter long specimen. In between there is a gradation in the measured

flame travel distances, and for five typical cellulosic loose fill insulations

the values ranged from 49 to >100 cm. These distances correspond to 0.34 to

<0.11 W/cm^ , respectively.

The test method has been thoroughly examined for repeatability and

reproducibility during its examination for carpets and other floor coverings

[9,10]. To further check the reproducibility of the test method when applied

7
Table 1. Test materials

Label information

Designation Description Specification ASTM E-84

G-1 Glass fiber blanket, unfaced HH-I-521D

R-19, 6 in thick Type I G-2 Glass fiber blanket. foil faced HH-I-521E

R-11, 3.5 in thick Type III G-3 Glass fiber blanket. unfaced HH-I-521D FSC 20

"friction fit," 3.5 in thick Type I SD 15

FC 20

G-4 Glass fiber pouring wool

G-5 Glass fiber blanket. Kraft paper HH-I-521E

faced, R-30, 9 in thick Type II G-6 Glass fiber blanket. Kraft paper HH-I-521E

faced, R-30, 9 in thick Type II G-7 Glass fiber blanket, :Kraft paper HH-I-521E

faced, R-30, 9 in thick Type II M-1 Mineral wool, high density HH-I-1030A

pouring wool, minimum density Type I 1.9 lb/ft2

P-1 Isocyanurate foam FSC 25

P-2 Polystyrene foam

P-3 Polyurethane foam FSC 30

P-4 Polyurethane foam

C-1 Cellulosic loose fill , fr

C-2 Cellulosic loose fill , fr. HH-I-515C

density 2.2 Ib/ft^,

R factor 3.7/in

C-3 Cellulosic loose fill , FR FSC 35

C-4 Cellulosic loose fill , same FSC 37 as above but 0.5% less FR

C-5 Cellulosic loose fill , untreated

C-6 Cellulosic loose fill , FR HH-I-515B FSC 25

density 2.1 Ib/ft^ SD 0 R factor 3.8/in FC 25

C-7 Cellulosic loose fill , fr. HH-I-515B

density 2.5 Ib/ft^

R factor 5.0/in

C-8 Cellulosic loose fill , FR, HH-I-515C FSC 25

density 2.1 Ib/ft^ SD 0 R factor 3.7/in FC 25

C-9 Cellulosic loose fill , FR,

C-10 Cellulosic loose fill , untreated

C-11 Cellulosic loose fill , fr HH-I-515C

C-12 Cellulosic loose fill , FR HH-I-515B

C-13 Cellulosic loose fill , FR HH-I-515C

Class 25

C-14 Cellulosic loose fill , FR HH-I-515C FSC 20

Type I SD 10

FC 0 C-15 Cellulosic loose fill , fr ASTM C739-73

8
Table 2. Attic floor radiant panel test results

Insulation

Designation Density

(Ib/ft^)

Distance

Burned

(cm)

Critical

Radiant

Flux

(W/cm^

)

Remarks

Glass Fiber

G-1 0.9 0 >1.0 DNI

G-2 0.7 0 >1.0 DNI - foil face up

G-3 0.7 0 >1.0 DNI

G-4 1.8 0 >1.0 DNI

G-5 0.8 100* <0.1* Paper face up

G-5 0.8 100* <0.1* Paper face up - longitudinal slit

G-6 100* <0.1* Paper face up

G-6 100* <0.1* Paper face up - longitudinal slit

G-1 100* <0.1* Paper face up

G-1 100* <0.1* Paper face up - longitudinal slit

Mineral Wool

M-1 3.0 0 >1.0 DNI

Cellular Plastic

P-1 2.1 0 >1.0 DNI

P-2 1.9 0 >1.0 DNI, melted away from

pilot flame

P-3 2.3 48 0.35

P-4 1.8 54 0.27

Cellulose Loose-fill

C-1 3.5 61 0.21

C-1 3.7 58 0.24

C-1 5.6 53 0.29

C-1 7.4 57 0.24 Tamped down to high density

C-1 2.4 58 0.23 Conditioned 22 hrs at 70°F

and 65% rh

C-1 3.8 67 0.18 Dried 27 hrs at 180°F

C-2 3.6 60 0.22

C-2 4.1 54 0.27

C-2 4.2 61 0.21 Dried 24 hrs at 180°F

C-2 4.7 60 0.22 Dried 24 hrs at 180°F

C-3 3.2 80 0.13

C-4 3.2 83 0.12

C-5 2.9 100 <0.1

C-6 2.2 95 <0.11

C-6 2.3 94 <0.11

C-6 2.3 97 <0.11

C-6 2.5 100 <0.1 Blown in by machine

C-1 2.1 100 <0.1

C-1 2.9 100 <0.1

C-1 3.0 100 <0.1

C-1 3.1 100 <0.1

C-1 4.4 100 <0.1

C-8 4.0 68 0.18

C-8 4.8 57 0.28

C-9 — 49 0.34

C-11 3.7 100 <0.1

C-11 3.8 96 <0.1

C-12 3.3 100 <0.1

C-12 3.5 100 <0.1

C-13 3.0 98 <0.1

C-13 3.0 100 <0.1

C-13 3.0 93 <0.11

DNI - Did not ignite.

•k Represents same results in each of three identical tests.

9
to cellulose insulation, a commercial test laboratory at our request ran two

selected samples of cellulosic insulation in their apparatus, following the

recommended procedure. Their results were within 5 percent of the NBS values.

In order to provide a reasonable assurance that flames will not propagate

extensively on the insulation as installed in an attic floor, a critical

radiant flux level of 0.12 W/cm^ is suggested. The basis for this choice is

given below. The test as carried out on flooring materials provides a distributed radiant heat flux ranging from 0.11 W/cm^ to 1.1 W/cm^ . In initial

studies on insulation materials, the radiant panel test was changed to operate

a range of heat flux from 0.03 to 0.35 W/cm^. Using this heat flux range,

the uncertainty in making measurements at or near the proposed critical

radiant flux level of 0.12 W/cm^ may be less. However in the present design

it was decided to use the test under the standard flux range now recommended

for conventional flooring materials, since this permits operation at a single

heat input setting and a single calibration. The possibility of operating

the apparatus at an alternate heat flux range in the future may be examined.

Under solar exposure the temperature likely to be reached on the underside of the attic roof, during summer conditions in certain areas of the

U.S., ranges up to 71°C (160°F) , equivalent to a blackbody irradiance of 0.08

W/cm^ . Taking into account the probability of other heat sources in the

attic and the added energy released if a fire starts, a 50 percent safety factor was added. This means that a fire should not propagate in the attic insulation,

if the energy delivered to the insulation is less than 0.12 W/cm^.

It may be noted that for the loose fill cellulosic insulations for which

the ASTM E-84 flame spread classifications (FSC) were available from the

labels, there was no apparent correlation with the attic floor radiant panel

test results. In fact, at least two FSC 25-labeled insulations had a measured

critical radiant flux of less than 0.11 W/cm^

.

5.2 Cigarette Smoldering Test

The basic problem was to devise a test method which would (a) provide a reliable index of smolder tendency and permit ratings of all types of (loose

fill) insulation over a wide spectrum, (b) involve a minimum of equipment,

and (c) be simple and expeditious.

A cigarette was used to initiate smoldering since it is a reasonably

uniform and reproducible ignition source. Using one cigarette placed on top

of cellulose loose fill insulation or two cigarettes — one on top and one embedded below the surface — it was found that one sample of untreated

cellulosic loose fill insulation smoldered and resulted in a significant

weight loss (18 percent) . One fire retardant treated cellulose loose fill

material smoldered considerably more than the untreated paper, giving a 10
weight loss of 41 percent.

Various test parameters were explored. The size of the metal box

specimen holder, specimen packing density, and cigarette placement were all

found to influence the results. Positioning the cigarette vertically and

having it burn downward was found advantageous, being a simpler procedure and

yielding a moderately intense exposure with only a single cigarette. The

test requires that the lighted cigarette end be placed so that it maintains

contact with the insulation. As used, the cigarette is a slowly moving heat

source that heats the material under test at an appropriately slow rate for

the initiation of smolder. It is not designed to simulate any particular

smoldering ignition source’, but is rather used as a means for inducing smoldering and evaluating the tendency of the material to continue to smolder.

The cigarette might be envisioned as a very small electrical heater of about

3 or 4 watts power with a surface area of about 1 sq cm at a temperature of

600°C to 700°C.

The cigarette smoldering test is described in detail in appendix C.

Test results are summarized in table 3. These results indicate that where

limited smoldering occurred, it was confined to the area in close proximity

to the cigarette and did not result in weight losses in excess of 15 percent;

on the other hand, appreciable smoldering resulted in weight losses ranging

from 16 percent to over 75 percent. This formed the basis for the recommendation that a weight loss in excess of 15 percent provides a reasonable criteria

of appreciable smoldering.

These results also suggest that the smoldering tendency generally increases

with increasing density. Since the density of loose fill insulation may

increase with vibration and elevated relative humidity, testing should be

done at a "settled" density (see section 5.2 of appendix C)

.

The temperature and humidity conditioning specified (21°C, 50 percent

rh) corresponds to standardized laboratory preconditioning of samples. Since

this may not account for dehydration or other effects at the elevated temperatures and low humidities possible in attics, further studies appear desirable.

5.3 Mockup Flame Spread Tests

A large mockup of a home attic space was constructed to examine the

extent to which flame propagation would occur when the material was mounted

in a larger scale simulation and exposed to a small flaming ignition at one

end. A 9 ft 4 in by 12 ft ( 2.84 by 3.66 m) attic floor was constructed of

nominal 2 by 6 inch hemlock joists 16 inches on centers. The bottom was covered with a nominal 5/8 inch thick gypsum board "ceiling." This arrangement provided seven parallel floor joist spaces approximately 12 ft (3.66 m)

long. A peaked roof section of nominal 3/8 inch plywood sheathing, nominal

11
Table 3. Smoldering combustion test results

Designation DensityWeight

loss % Remarks

Designation Density

Weight

loss % Remarks

C-1 2.2 26 C-9 2.2 36

2.2 18 2.2 47

2.2 24

C-10 1.7 60

C-2 2.2 1 1.8 60

2.3 1 2.3 < 1 C-11 2.5 52

2.4 < 1 2.5 43

2 . 3* < 1* 8 mm hole 2.5 48

2.3 < 1 12 mm hole

2.3 2 12 mm hole C-12 1.8 65

2.3* < 1* 16 mm hole 1.8 65

2.3* < 1* Tapered hole 1.8 66

1.8 4 2.0 68

1.8 16 2.0 65

1.8 2 2.0 70

2.0 < 1 3.0 75

2.0 56 3.0 75

2.0 4 3.0 74

3.0 28 4.0 77

3.0 3 4.0 78

3.0 16 4.0 77 3.0 45 2.6 56 8 mm hole

3.0 62 2.6 61 8 mm hole

3.0 62 2.6 61 8 mm hole

3.0 3 2.6 58 12 mm hole

3.0 42 2.6 57 12 mm hole

3.0 24 2.6 42 12 mm hole

3.0 34 2.6 1 16 mm hole

4.0 70 2.6 57 16 mm hole

4.0 66 2.6 58 16 mm hole

4.0 68 2.6 58 Tapered hole

2.6 59 Tapered hole

C-3 2.1 66 2.6 57 Tapered hole

2.1 59

C-13 3.0 60

C-5 1.7 42 3.0 65

3.0 60

C-6 2.1 53

2.1 54 C-14 4.5 64

2.2 53 3.0 42

2.2 54

3.0 31 G-5 1.0 0 3.0 28 paper

3.0 29 faced

C-1 2.2 65 P-2 1.8 0 2.2 65

P-4 1.8 0 C-8 2.1 0 2.1 0 2.2 < 1 2.2 < 1 3.0 37

3.0 26

3.0 38

3.0 40

Represents same results in each of three identical tests.

12
2 by 6 inch roof rafters, and mineral wool blanket insulation between the

rafters was built as a removable subassembly which could be placed to fit over the attic floor assembly. Electrical heating coils were mounted along

the top, inside the roof, to generate elevated attic air temperatures, con- trollable up to 82°C (180°F) . A series of five propane burner tips connected

through a common manifold was mounted so that the assembly could provide a simultaneous flaming ignition source at the end of each of the five central

floor joist spaces. The outer two floor joist spaces were not used.

In one test, the attic air temperature was raised to and maintained at

71°C (160°F) , corresponding to an estimated heat flux level of 0.08 W/cm^ at

the top of the joists. The following materials were placed in the joist

spaces flush with the top of the joists: G-5 paper exposed, G-5 glass fiber

exposed, C-6, C-10 and C-11, cellulosic insulation (see table 1 for descriptions) . The cellulosic loose fill materials were applied at a nominal density

of 2.5 Ib/ft^ (40 kg/m^). The glass fiber blanket was tested with the paper

facing exposed as well as unexposed since it has been reported that mineral

wool blankets are sometimes installed with the facing exposed.

Upon exposure to the flames from the propane burner, there was rapid and

extensive spread of flame along the untreated cellulose (C-10) involving

flames extending vertically approximately 6 to 12 inches (15 to 30 cm) ; there was a slow and continuous propagation of short flames along the entire upper

surface of C-11. There was a slight flaming involvement and spread away from

the burner on the surface of C-6, but the flames did not extend more than

12 in (30 cm) from the burner. The paper-exposed glass fiber ignited and

produced 8 to 12 in (20 to 30 cm) tall flames which propagated slowly away

from the burner but did not travel the complete joist space. There was very

little propagation along the glass-fiber exposed insulation.

In a second test, the same procedure was repeated (with materials C-6,

C-10 and C-11, but not material C-5) , except the attic air temperature was raised and maintained at 82°C (180°F) , corresponding to a heat flux of 0.12

W/cm^ at the top joist surface level. In this test, the C-10 and C-11 materials

propagated flames in a similar manner (but slightly more rapidly) , and the C-6

material also propagated flames at a slow rate the full length of the insulated

portion of the joist space.

In a third test, the three center joist spaces contained three types of

paper-faced glass fiber insulation with the paper facing exposed on top and

cut lengthwise in the center to simulate tears in the paper. The attic air

temperature was maintained at 71°C (160°F) . Upon exposure to the pilot

burner flames, there was immediate involvement of the paper facing and flames

progressed steadily, primarily along the cut edges. Within 4 minutes, the

entire attic space was enveloped in flames.

13
These tests were conducted with no forced or induced air motion (no vent

openings were provided and the roof-air mounted smoke exhaust fan was not

actuated). However, it is apparent that propagation of flames along the

upper surface of certain loose fill and exposed paper-faced blanket insulation

placed in attic floor joists will occur at elevated temperatures and in the

presence of a small pilot flame. These tests are a validation of the experimental arrangement and test conditions selected for measuring surface flame

propagation in the attic floor radiant panel test.

5.4 Mockup Smoldering Tests

A smaller mockup of a home attic space, consisting of three joist spaces

in a 48 by 48 inch (120 by 120 cm) box, was constructed and used for trial

and error testing of several possible fire scenarios. The major ones contemplated were:

• Recessed light fixture covered with insulation.

• Other electrical devices (motors, ballasts, junction boxes),

heated flue pipes, chimneys, etc. surrounded by insulation.

An initial series of tests confirmed that an overlamped recessed light

fixture covered with a sample of R-35 cellulosic loose fill insulation could

produce a self-propagating smoldering fire. A sample of glass fiber insulation (R-35) did not produce a smoldering fire in or near the fixture. Tests were also conducted to see if fires would be initiated with thermally insulated, electrically overloaded plastic- j acketed wiring with excessive current

overloads. Smoldering fires were initiated at overloads corresponding to 190

to 200 percent of rated current. Further tests were not conducted since the

practical limit of overload in a fused circuit is 35 percent.

A second series of tests was conducted using a recessed light fixture

centrally located in a 16-inch joist space and covered with insulation. The

insulation materials included most of the materials previously subjected to

the cigarette smoldering test. The material was blown into the joist spaces

using a commercial blowing machine. The results are shown in table 4. It

should be noted that the smoldering reaction is slow and generally requires

several hours before the reaction reaches the stage where considerable smoke

is generated and where the heating of the joists starts to take place. Using

a 150-W bulb in a fixture rated for 100 W produced smoldering ignition of seven of the eight materials tested. Using a 100-W bulb with 9-1/4 inches

(23.5 cm) of cellulosic loose fill insulation did not produce smoldering

ignition. The cigarette smoldering test produced extensive smoldering (more

than 15% weight loss) in five of the eight materials tested. Thus, these

results indicate a strong likelihood that smoldering ignitions will occur

14
Table

4.

Mockup

smoldering

combustion

tests

Q)

5-1 g

-pX

•H

+Jr:

Cn

^3

0)tn

cn

0)u

o

g

CDo

cc:

(Up

fO>

ec;

>1

-p

cr>4-) CN CN CN CN •H MM • • • « CD CN <N CN CN C

(U Q

X

fii Oi CM

ro

inm

VD ID

00

+J

CD

0) -P

(U -P

-P

0)P

rOtn •Hu

Pm Pm Pm Pm Pm Pm Pm

0^

•5^ 00 o

to

LD

IT) LO OO <«:J* in

in

in

V£> 00

>1

+j

CO-p CN in 00 00 00 O CN *H ip • • • • • • • • • CD \ <N CN CN CN CN 00 CN 00 <N C

CD Q

Xi

1—

1

4J W rH iH cn -H

!3 fO fO

CO 04 Cm

0) II II 04 Pm

Pm Pm Pm 04 Pm Pm Oh

x: CO

CO ^

•H O o\o <D n-i ^

S:

0^J V£) <N

in

in CN O

VX) 00

-p

rM CN 00 1—

!

1—

1

CN 1—

!

CN o CN

CD • C X! CN CN CN 1—

1

CN (N CN CN 1—

1

CN CN

O rH in p 1—

1

CN 00 in V£) r- 00 (Ti r—

1

0) 1 1 1 1 1 1 1 1 1 1 1 -p

fO s u u u u u u u u u u u

15

Note:

"P"

indicates

less

than

15%

weight

loss

in

cigarette

test

and

no

extensive

smoldering

in

light

fixture

test.

"F"

indicates

a

weight

loss

of

15%

or

more

in

cigarette

test

and

extensive

smoldering

in

light

fixture

test.
where cellulose loose fill insulation is applied directly over overlamped

recessed light fixtures. Also the simple cigarette smoldering test will

screen out many, but probably not all, materials which will permit the propagation of smoldering in a recessed light fixture scenario which might be

encountered in residential use.

.6. SUMMARY AND CONCLUSIONS

6.1 Insulation intended for use in residential applications should be

tested and rated for those properties which measure its tendency to be a principal source or contributor to fire. As a minimum, insulation intended

for use in attics should be tested for tendency to smolder, and tendency to

propagate open flaming under radiant heat exposure.

6.2 The complete insulation assembly should be tested in the form in

which it is intended to be used or in which it may reasonably be expected to

be used. Based on the results in section 5.3, it is suggested that HH-I-521E

be revised to remove the current exclusion on testing of the membrane covering

on the insulation blanket in view of known experience with the insulation

being used with the paper face exposed, unless adequate measures can be

devised to guarantee against this application.

6.3 Tests have shown that attic floor insulation materials which propagate flames over the entire length of the specimen surface in the attic

flooring radiant panel test will also result in surface flame propagation in an attic floor construction assembly under conditions simulated by the test.

Likewise, materials which permit the propagation of smoldering in the simple

cigarette smoldering test will result in the propagation of smoldering in

insulation applied directly over a typical (but overlamped) recessed light

fixture, a condition which may reasonably be expected to be encountered in

residential use.

6.4 Federal specifications for the three types of materials should be

revised to incorporate more appropriate heat and flame exposure tests. For

the three particular specifications under discussion, the recommended test

methods are the Attic Floor Radiant Panel Test- and a cigarette smoldering

test

.

To allow for the elevated temperatures likely to be

reached in attics and the presence of flaming ignition

sources, a critical radiant flux of 0.12 W/cm^ measured

in the Attic Floor Radiant Panel Test is the minimum

suggested level.

16
In the Smoldering Combustion Test, it is suggested

that a suitable criterion is a weight loss of less than

15 percent of the initial weight with no evidence of

flaming combustion.

In addition, all insulation should be labeled to indicate (a) conformance with

the specifications and (b) cautions about fire dangers if applied improperly.

7 . ACKNOWLEDGMENTS

The tests and analysis provided in this study were accomplished in a short time span through the team efforts of several members of the Center for

Fire Research. The contributions of the following individuals is gratefully

acknowledged

S. Davis

R. McCarter

B. Buchbinder

W. H. Bailey

D. Evans

T. Prather

J. S. Steel

Attic Floor Radiant Panel Test

Cigarette Smoldering Test

Fire Statistics

Assembling Apparatus,

Preparation of Specimens,

Conducting Fire Tests

17
8. REFERENCES

[1] National Electrical Code, NFPA 70, Section 410-66, National Fire

Protection Association, 470 Atlantic Ave., Boston, Mass. 02210.

[2] Manual on Clearances for Heat-Producing Appliances, NFPA 89M,

National Fire Protection Association, 470 ?^tlantic Ave., Boston,

Mass. 02210.

[3] Standard Test Method for Surface Burning Characteristics of Building

Materials, ASTM E-84-77, American Society for Testing and Materials,

1916 Race Street, Philadelphia, Pa. 19103.

[4] Standard method of test for surface burning characteristics of flooring.

Floor Covering and Miscellaneous Materials, ULC-S102 . 2-1977

,

Underwriters' Laboratories of Canada, 7 Crouse Rd. , Scarborough,

Ontario

.

[5] Standard Specification for Cellulosic Fiber (Wood Base) Loose Fill

Thermal Insulation, ASTM C739-77, American Society for Testing and

Materials, 1916 Race Street, Philadelphia, Pa. 19103.

[6] Standard Test Method for Noncombustibility of Elementary Materials,

ASTM E-136-73, American Society for Testing and Materials, 1916 Race

Street, Philadelphia, Pa. 19103.

[7] Anderson, R. W. and Wilkes, P. , Survey of Cellulosic Insulation

Materials, Energy Research and Development Administration,

Department of Energy (U.S.), ERDA 77-23 (January 1977).

[8] Test for Critical Radiant Flux of Carpet Flooring Systems (Flooring

Radiant Panel Test), Federal Test Method Standard No. 372 (August 31,

1977) .

[9] Benjamin, I. A. and Adams, C. H. , The flooring radiant panel test

and proposed criteria, Fire Journal, Vol. 70, No. 2, 63-70 (March 1976).

[10]

Benjamin, I. A. and Adams, C. H., Proposed Criteria for Use of the

Critical Radiant Flux Test Method, National Bureau of Standards (U.S.),

NBSIR 75-950 (December 1975)

.

18
APPENDIX A. FIRE INCIDENT DATA ON THERMAL INSULATION

A review and analysis was made of available data on fire incidents

involving thermal insulation for two principal reasons: first, to get some feeling for the magnitude of the current home insulation fire problem and

second, to describe the typical scenarios for fires involving insulation.

Although this review was made, we were aware that the current retrofit move- ment is new, and particularly the home-owner application, so that existing

statistics would be inadequate to reflect what might be a new and serious

problem.

There are the following limitations on what can be learned from the

data

:

1. Current data do not at all reflect the potential problems

from retrofit of extra amounts of insulation in homes.

This might bring flammable insulation closer to potential

ignition sources, reduce available air for cooling of

fixtures and wiring, etc.

2. The data bases available to us are the National Fire

Protection and Control Administration (NFPCA) National

Fire Incident Reporting System (NFIRS) and the NFPA

Field Incident Data Organization (FIDO) . Both of these

data bases identify only the first material ignited.

We get no information on fires wherein insulation may

play a significant role in fire growth, although

another material is ignited first.

3. NFIRS is not yet national, and the data cover one year

(1975) for California and five quarters (1976 and 1st

quarter 1977) for Ohio.

The data available include a listing of 496 incidents from NFIRS, and

28 incidents from FIDO. The NFIRS data covers all incidents reported in

residential occupancies (NFPA 901 codes in 400 series of fixed property)

where "thermal, acoustical insulation within wall, partition, or floor/

ceiling space" (code 18 for form of material ignited) was the first material

ignited (FMI) . The 28 incidents from FIDO cover five years of reports on "serious fires." The FIDO system is heavily biased toward large loss or fatal fires.

The typical fires reported may be described by looking at the composition

of the insulation and the ignition source. Each of these factors is represented by two data elements in NFIRS. The "first material ignited (FMI)" is

described. In addition to the FMI, there is a data element entitled "type

of material ignited (TMI) ." The TMI for these insulation cases is tabulated

19
in table A1 . We see that fiberboard is identified 18 percent of the time,

with other cellulosic categories heavily represented. These materials include

most of the cellulose-based insulations. Note that the wood/paper total

(code 69) should be added to the totals for the more specific categories such

as 63, 65 and 67. We see that cellulose-base materials (e.g. wood, paper)

play a significant role as the first material ignited.

The ignition source is defined by two data elements, "equipment involved

in ignition" and "form of heat of ignition (FHI)." The distribution of the

FHI code for our NFIRS cases is shown in table A2 . Short circuits, at 27

percent, is the single largest category. When combined with the remainder of

the "heat from electrical equipment" category, the 20-29 group of codes

accounts for 37 percent of the total.

"Torches and open flames" (codes 40-49) represent 23 percent of the cases. Within this category, torches alone total 82 cases (18%), with

plumber's torches comprising 69 of these (15%). Some other subtotals of

interest include 21 "electric lamp or bulb" cases (5%) , 16 "properly

operating electrical equipment" cases (3%) , seven cases for matches, and seven cases for lightning.

The 28 FIDO cases encompassed mobile property (mobile homes, travel

trailers) in addition to the 400 code series for fixed property. Plumber's

torches (13) and short circuits (9) were the only FHI codes to appear more

than once. For TMI , 10 of the cases had either "fiberglass," "paper on fiberglass," or "paper on insulation" listed. Four cases listed fiberboard.

There were only three other cases with TMI listed, two were "straw," one

was "plastic."

In terms of occupancy, the FIDO cases were classified as follows:

Mobile homes 9 Apartments

Travel trailers

Single family dwellings

Hotel

Dormitory

Motor home

Recreational vehicle

6

5

4

1

11

1

20
Table Al . Distribution of NFIRS insulation

by type of material ignited

Form of material Codes

Cases

Number Percentage

Fiberboard 66 86 18

Wood 63,65 72 15

Untreated paper 67 43 9 Fabric (man made fiber) 71 39 8 Wood/paper 69 37 8 Plastic 45,59 26 5 Rubber 51 21 4 Treated paper 83 17 3 Other — 60 12

Unclassified — 90 18

Total 491 100

Table A2 . Distribution of NFIRS

incidents by form of heat of

insulation

ignition

Cases

Form of heat of ignition Codes Number Percentage

Short circuit 21-24 125 27

Torches and open flames 40-49 105 23

Sparks and heat from gas, liquid

and solid fueled equipments 10-19 86 19

Heat from hot object 50-59 75 16

Heat from electrical equipment,

excluding short circuits 20,25-29 48 10

Other — 24 5 Total 463 100

21
APPENDIX B.

STANDARD METHOD OF TEST FOR CRITICAL

RADIANT FLUX OF EXPOSED ATTIC

FLOOR INSULATION USING A RADIANT

HEAT ENERGY SOURCE

1. Scope

1.1 This method of test describes a procedure for measuring the critical

radiant flux of exposed attic floor insulation subjected to a flaming ignition source in a graded radiant heat energy environment, in a test chamber. The

test specimen may consist of loose-fill insulation, insulation batts, foam

board insulation, or other form intended for the purpose.

1.2 This method measures the critical radiant flux at flame-out. It

provides a basis for estimating one aspect of fire exposure behavior for attic

floor insulation. The imposed radiant flux embraces the thermal radiation

levels likely to impinge on the floor of an attic whose upper surfaces are heated by solar radiation and exposed to an open flame.

2 . Summary of Method

2.1 The basic elements of the test chamber (figure Bl) are: 1) an air-gas fueled radiant heat energy panel inclined at 30° and directed at

2) a horizontally-mounted attic floor insulation specimen (figure B2)

.

The

radiant panel generates a radiant energy flux distribution ranging along the

100-cm length of the test specimen from a nominal maximum of 1.0 W/cm^ to a minimum of 0.1 W/cm^ . The test is initiated by open flame ignition from a pilot burner. The distance burned to flame-out is converted to W/cm^ from

the flux profile graph (figure B8) and reported as critical radiant flux , W/cm^

.

3. Significance

3.1 This method of test is designed to provide a basis for estimating

one aspect of the fire exposure behavior of an attic floor insulation in a building attic. The test environment is intended to simulate conditions that

have been observed and defined in full-scale attic experiments.

3.2 The test is intended to be suitable for regulatory purposes,

specification acceptance, design purposes, or development and research.

3.3 The fundamental assumption inherent in the test is that "critical

radiant flux" is one measure of the sensitivity to flame spread of attic

floor insulation installed in a building attic.

3.4 The test is applicable to attic floor insulation specimens

installed by acceptable installation practice.

4. Definition of Terms

4.1 Critical Radiant -Flux is the level of incident radiant heat energy

on the attic floor insulation system at the most distant flame-out point.

It is reported in W/cm^.

4.2 Flux Profile is the curve relating incident radiant heat energy on the specimen plane to distance from the point of initiation of flaming

ignition, i.e., 0 cm.

4.3 Total Flux Meter is the instrument used to measure the level of

radiant heat energy incident on the specimen plane at any point.

22
4.4 Black Body Temperature is the temperature of a perfect radiator - a surface with an emissivity of unity and, therefore, a reflectivity of zero.

5. Radiant Panel Test Chamber - Construction and Instrumentation

5.1 The radiant panel test chamber employed for this test shall be

located in a draft-protected laboratory.

5.1.1 The radiant panel test chamber, figures B3 and B4, shall consist

of an enclosure 140 cm (55 in) long by 50 cm (19-1/2 in) deep by 71 cm (28 in)

above the test specimen. The sides, ends and top shall be of 1.3 cm (1/2 in)

calcium silicate board, such as Marinite XL, 0.74 g/cm^ (46 Ibs/ft^) nominal

density, with a thermal conductivity @ 93°C (200°F) of 0.0011 W/cm °C

(0.77 Btu-in/hr ft^ °F) . One side shall be provided with an approximately

10 cm X 110 cm (4 x 44 in) draft tight fire resistance glass window so that

the entire length of the test specimen may be observed from outside the fire

test chamber. On the same side and below the observation window is a door

which, when open, allows the specimen platform to be moved out for mounting

or removal of test specimens. A draft tight fire resistant observation

window may be installed at the low flux end of the chamber.

5.1.2 The bottom of the test chamber shall consist of a sliding steel

platform which has provisions for rigidly securing the test specimen holder

in a fixed and level position. The free, or air access, area around the

platform shall be in the range of 1950-3550 cm^ (300-500 sq in)

.

5.1.3 The top of the chamber shall have an exhaust stack with interior

dimensions of 12.5 cm (5 in) wide by 38 cm (15 in) deep by 30 cm (12 in)

high at the opposite end of the chamber from the radiant energy source.

5.2 The radiant heat energy source shall be a panel of porous

refractory material mounted in a cast iron frame, with a radiation surface

of 30.5 X 45.7 cm (12 by 18 in). It shall be capable of operating at

temperatures up to 816°C (1500°F). The panel fuel system shall consist of

a venturi-type aspirator for mixing gas and air at approximately atmospheric pressure, a clean dry air supply capable of providing 28.3 NTP m^ per

hr (1000 Standard Cubic Feet per Hour) at 7.6 cm (3.0 in) of water, and

suitable instrumentation for monitoring and controlling the flow of fuel to

the panel.

5.2.1 The radiant heat energy panel is mounted in the chamber at 30° to

the horizontal specimen plane. The horizontal distance from the 0 mark on

the specimen fixture to the bottom edge (projected) of the radiating surface

of the panel is 8.9 cm (3-1/2 in). The panel to specimen vertical distance

is 14 cm (5-1/2 in) (see figure B3) . The angle and dimensions given above

are critical in order to obtain the required radiant flux.

5.2.2 The radiation pyrometer for standardizing the thermal output of

the panel shall be suitable for viewing a circular area 25.4 cm (10 in) in

diameter at a range of about 1.37 m (54 in). It, shall be calibrated over

the black body temperature range of 490-510°C (914-950°F) in accordance with

the procedure described in appendix A.

5.2.3 A high impedance potentiometer with a suitable millivolt range

shall be used to monitor the output of the radiation pyrometer described in

5.2.2.

5.3 The dummy holder (see figure B5) , is constructed from heat-resistant

stainless steel^ having overall dimension of 115 cm (45 in) by 32 cm (12-3/4 in)

with a specimen opening of 20 cm (7.9 in) x 100 cm (40 in) . Six slots are

cut in the flange on either side of the holder to reduce warping. The holder

is fastened to the platform with two stud bolts at each end.

^AISI Type 300 (UNA-N08330) or equivalent, thickness 0.198 cm (0.078 in).

23
5.4

The specimen tray (see figure B6) is constructed from heatresistant stainless steel^ having overall dimensions of 110 cm (43.3 in) by

27.3 cm (10.8 in); the depth of the tray is 5 cm (2 in). The flanges of the

specimen tray are drilled to accommodate two stud bolts at each end; the

bottom surface of the flange is 2.1 cm (0.83 in) below the top edge of the

specimen tray.

5.5

The pilot burner, used to ignite the specimen, is a commercial

propane venturi torch^ with an axially symmetric burner tip having a propane

supply tube with an orifice diameter of 0.0076 cm (0.003 in). In operation,

the propane flow is adjusted to give a pencil flame blue inner cone length

of 1.3 cm (1/2 in). The pilot burner is positioned so that the flame generated

will impinge on the centerline of the specimen at the 0 distance burned point

at right angles to the specimen length (see figures B3 and B4) . The burner

shall be capable of being swung out of the ignition position so that the

flame is horizontal and at least 5 cm (2 in) above the specimen plane.

5.6

Two 0.32 cm (1/8 in) stainless steel sheathed grounded junction

chromel alumel thermocouples^ are located in the Flooring Radiant Panel Test

Chamber (see figures B3 and B4) . The chamber thermocouple is located in the

longitudinal central vertical plane of the chamber 2.5 cm (1 in) down from

the top and 10 cm (4 in) back from the inside of the exhaust stack. The

exhaust stack thermocouple is centrally located 15.2 cm (6 in) from the top.

5.6.1

An indicating potentiometer with a range of 100-500°C (212-932°F)

may be used to determine the chamber temperatures prior to a test.

5.7

An exhaust duct with a capacity of 28.3-85 NTP m^ per minute

(1000-3000 SCFM) decoupled from the chamber stack by at least 7.6 cm (3 in) on all sides and with an effective area of the canopy slightly larger than

the plane area of the chamber with the specimen platform in the out position

is used to remove combustion products from the chamber. With the panel turned

on and the dummy specimen in place, there should be no measurable difference

in air flow through the chamber stack with the exhaust on or off.

5.8

The dummy specimen which is used in the flux profile determination

shall be made of 1.9 cm (3/4 in) inorganic 0.74 g/cm^ (46 Ibs/ft^) nominal

density calcium silicate board, such as Marinite XL (see figure B5) . It is

25 cm (10 in) wide by 107 cm (42 in) long with 2.7 cm (1-1/16 in) diameter

holes centered on and along the centerline at the 10,20,30, ..., 90 cm

locations, measured from the maximum flux end of the specimen.

5.8.1 The total heat flux transducer used to determine the flux profile

of the chamber in conjunction with the dummy specimen should be of the

Schmidt-Boelter'^ type, have a range of 0-1.5 W/cm^ (0-1.32 Btu/ft^ s) , and

shall be calibrated over the operating flux level range of 0.10 to 1.5 W/cm^

in accordance with the procedure outlined in Annex A. A source of 15-25°C

cooling water shall be provided for this instrument.

5.8.2 A high impedance or potentiometric voltmeter with a range of 0-10

m.v. and reading to 0.01 m.v. shall be used to measure the output of the

total heat flux transducer during the flux profile determination.

5.9

A timer shall be conveniently mounted on the chamber for measuring

preheat and pilot contract time.

^ANSI Type 300 (UNA-N08330) or equivalent, thickness 0.198 cm (0.078 in).

^BERNZ-O-MATIC TX 101 or equivalent.

3 Thermocouples should be kept clean to insure accuracy of readout.

4 Medtherm 64-2-20 will meet this requirement.

24
6.

Safety Procedures

6.1 The possibility of a gas-air fuel explosion in the test chamber

should be recognized. Suitable safeguards consistent with sound engineering

practice should be installed in the panel fuel supply system. These may

include one or more of the following: (1) a gas feed cut-off activated when

the air supply fails, 2) a fire sensor directed at the panel surface that

stops fuel flow when the panel flame goes out, 3) a commercial gas water

heater or gas-fired furnace pilot burner control thermostatic shut-off which

is activated when the gas supply fails or other suitable and approved device.

Manual reset is a requirement of any safeguard system used.

6.2 In view of the potential hazard from products of combustion, the

exhaust system must be so designed and operated that the laboratory environment is protected from smoke and gas. The operator should be instructed to

minimize his exposure to combustion products by following sound safety

practice, e.g., insure exhaust system is working properly, wear appropriate

clothing including gloves, et al.

7.

Sampling

7.1 The samples selected for testing shall be representative of the

product

.

7.2 Standard ASTM sampling practice shall be followed where applicable,

see ASTM Method E-122.

8.

Test Specimens

8.1 The test specimen shall be attic floor insulation of sufficient

size to fill the specimen tray to a depth of 5 cm (2 in)

.

8.2 Insofar as possible, the attic floor insulation specimen should

simulate actual installation practice. Typical examples follow:

8.2.1 Loose-fill insulation blown in to fill the tray, then carefully

screeded to provide a depth of 5 cm in the tray.

8.2.2 Loose-fill insulation poured in to fill the tray, then carefully

screeded to provide a depth of 5 cm in the tray.

8.2.3 Insulation batts sliced to a depth of 5 cm and cut to fit into

the tray.

8.2.4 Foam board insulation cut to fit into the tray to a depth of

5 cm.

8.3 A minimum of three specimens per sample shall be tested.

8.4 The density of the specimen tested shall be determined by weighing

the specimen tray just prior to testing.

9.

Radiant Heat Energy Flux Profile Standardization

9.1

In a continuing program of tests, the flux profile shall be

determined not less than once a week. Where the time interval between tests

is greater than one week, the flux profile shall be determined at the start

of the test series.

25
9.2 Mount the dummy specimen in the mounting frame and attach the

assembly to the sliding platform.

9.3 With the sliding platform out of the chamber, ignite the radiant

panel. Allow the unit to heat for one hour. The pilot burner is off during

this determination. Adjust the fuel mixture to give an air-rich flame. Make

fuel flow settings to bring the panel to an apparent black body temperature

as measured by the radiation pyrometer, of about 500°C (932°F) , and the

chamber temperature to about 180°C (356°F). When equilibrium has been

established, move the specimen platform into the chamber.

9.4 Allow 0.5 hours for the closed chamber to equilibrate.

9.5 Measure the radiant heat energy flux level at the 40 cm point with

the total flux meter instrumentation. This is done by inserting the flux

meter in the opening so that its detecting plane is 0.16-0.32 cm (1/16-1/8 in)

above and parallel to the plane of the dummy specimen and reading its output

after 30 + 10 seconds. If the level is within the limits specified in 9.6

the flux profile determination is started. If it is not, make the necessary

adjustments in panel fuel flow. A suggested flux profile data log format is

shown in figure B7.

9.6 The test shall be run under chamber operating conditions which give

a flux profile as shown in figure B8. The radiant heat energy incident on

the dummy specimen shall be between 0.87 and 0.95 W/cm^ (0.77 and 0.83 Btu/ft^

sec) at the 20 cm point, between 0.48 and 0.52 W/cm^ (0.42 and 0.46 Btu/ft^

sec) at the 40 cm point and between 0.22 and 0.26 W/cm^ (0.19 and 0.23 Btu/ft^

sec) at the 60 cm point.

9.7 Insert the flux meter in the 10 cm opening following the procedure

given in 9.5 above. Read the m.v. output at 30 + 10 seconds and proceed to

the 20 cm point. Repeat the 10 cm procedure. The 30 - 90 cm flux levels are determined in the same manner. Following the 90 cm measurement, make a check

reading at 40 cm. If this is within the limits set forth in 9.6, the test

chamber is in calibration and the profile determination is completed. If not,

carefully adjust fuel flow, allow 0.5 hours for equilibrium and repeat the

procedure

.

9.8 Plot the radiant heat energy flux data as a function of distance

along the specimen plane on rectangular coordinate graph paper. Carefully,

draw the best smooth curve through the data points. This curve will hereafter

be referred to as the flux profile curve.

9.9 Determine the open chamber apparent black body and chamber temperatures that are identified with the standard flux profile by opening the door

and moving the specimen platform out. Allow 0.5 hours for the chamber to

equilibrate. Read the radiation pyrometer output and record the apparent

black body temperature in °C. This is the temperature setting that can be

used in subsequent test work in lieu of measuring the radiant flux at 20 cm,

40 cm, and 60 cm using the dummy specimen. The chamber temperature also

should be determined again after 0.5 hours and is an added check on operating

conditions

.

26
10.

Conditioning 10.1

Test specimens are to be conditioned to equilibrium or a minimum

of 48 hours, whichever is greater, at 21 + 3°C (69.8 + 5.4°F) and a relative

humidity 11. of 50 + 5 percent immediately prior to testing.

Test Procedure

11.1

With the sliding platform out of the chamber, ignite the radiant

panel. Allow the unit to heat for one hour^. Read the panel apparent

black body temperature and the chamber temperature. If these temperatures

are in agreement to within +5°C with those determined in accordance with

9.9 above, the chamber is ready for use.

11.2

Mount the specimen tray on the sliding platform and position with

stud bolts (see figure B9)

11.3

Ignite the pilot burner, move the specimen into the chamber, and

close the door. Start the timer. After 2 minutes preheat, with the pilot

burner on and set so that the flame is horizontal and 5 cm above the specimen,

bring the pilot burner flame into contact with the center of the specimen at

the 0 cm mark. Leave the pilot burner flame in contact with the specimen for

5 minutes, then remove to a position 5 cm above the specimen and leave burning

until the test is terminated.

11.4 If the specimen does not ignite within 5 minutes following pilot

burner flame application, the test is terminated by extinguishing the pilot

burner flame. For specimens that do ignite, the test is continued until the

flame goes out. Observe and record significant phenomena, such as discoloration, charring, smoldering, etc.

11.5 When the test is completed, the door is opened, the specimen platform is pulled out.

11.6 Measure the distance burned, i.e., the point of farthest advance

of the flame front, to the nearest 0.1 cm. From the flux profile curve,

convert the distance to W/cm^ critical radiant heat flux at flame out. Read

to two significant figures. A suggested data log format is shown in figure

BIO.

11.7 Remove the specimen tray from the moveable platform.

11.8 The succeeding test can begin as soon as the panel apparent black

body temperature and chamber temperature are verified (see 11.1). The speci- men tray should be at room temperature prior to insertion of the next specimen.

12.

Report

12.1 The report include the following:

12.1.1 Description of the attic floor insulation.

12.1.2 Description of the procedure used to prepare the floor

insulation specimen.

^It is recommended that a sheet of inorganic millboard be used to cover the

opening when the hinged portion of the front panel is open and the specimen

platform is moved out of the chamber. The millboard is used to prevent

heating of the specimen and to protect the operator.

27
12.1.3 Number of specimens tested, including critical radiant flux

and density for each specimen as tested.

12.1.4 Observations of the burning characteristics of the specimen,

such as discoloration, charring, smoldering, etc.

28
ANNEX A

PROCEDURE FOR CALIBRATION OF RADIATION INSTRUMENTATION

A1 . Radiation Pyrometer

A1 . 1 Calibrate the radiation pyrometer by means of a conventional

black body enclosure placed within a furnace and maintained at uniform

temperatures of 490, 500, and 510°C (914, 932, 950°F) . The black body

enclosure may consist of a closed chromel metal cylinder with a small sight

hole in one end. Sight the radiation pyrometer upon the opposite end of

the cylinder where a thermocouple indicates the black body temperature.

Place the thermocouple within a drilled hole and in good thermal contact

with the black body. When the black body enclosure has reached the

appropriate temperature equilibrium, read the output of the radiation

pyrometer. Repeat for each temperature.

A2 . Total Heat Flux Meter

A2 . 1 The total flux meter shall be calibrated by the National Bureau

of Standards^, or alternatively, its calibration shall be developed by

transfer calibration methods with an NBS calibrated flux meter. This

latter calibration shall make use of the radiant panel tester as the

heat source. Measurements shall be made at each of the nine dummy specimen

positions and the mean value of these results shall constitute the final

calibration

.

A2 . 2 It is recommended that each laboratory maintain a dedicated

calibrated reference flux meter against which one or more working flux

meters can be compared as needed. The working flux meters should be

calibrated according to the procedure of A2 . 1 at least once per year.

Direct requests for such calibration services to the: Optical Radiation

Section, 232.04, National Bureau of Standards, Washington, D.C. 20234.

29
30

>

i

Figure

Bl.

Radiant

panel

test

chamber
1 31

Figure

B2.

Horizontally-mounted

attic

floor

insulation

specimen
Figure B3. Flooring radiant panel tester

schematic - side elevation

32
RADIATION PYROMETER

PROTECTIVE SLEEVE

Figure B4. Flooring radiant panel tester

schematic - low flux end, elevation

33
Figure B5. Dummy specimen holder

34
108 cm

• 1.0 cm

5 cm T

Figure B6. Specimen tray

35
RADIANT FLUX PROFILE

Date

Black Body Temperature ^m.v. °C (°F)

Gas Flow NTPm^H (SCFH) Air Flow ^NTPm^H (SCFH)

Room Temperature °C (°F)

Air Pressure Gas cm (in) of H 2 O

Flux Meter Conversion Factor

Radiometer No. from Calibration on

Distance MV Watts/cm^

(cm)

10

2 0

30

40

50

6 0

70

80

90

Signed

Figure B7. Flux profile data log format

36
o

^luo/SiiVM

37

DISTANCE,

cm
Figure

B8.

Standard

radiant

heat

energy

flux

profile

Figure B9. Specimen tray mounting position

38

I

V
Test Number

Laboratory

Date

Specimen Identification/Code No

Test Assembly:

Panel : Angle °

Flow: Gas

Temperature

NTPm H (SCFH) Air

Pressure, cm (in) H2O: Initial, Air

Chamber Temperature (Initial)

Room: Temperature

Flame Front Out

All Flame Out

Gas

’C (°F)

°C (°F) Hood Draft

min.

min

.

Time

“C (°F)

NTPm H

cm (in) water

Total Burn Length cm (in)

Critical Radiant Flux watts/cm‘‘

Flux Profile Reference

Observations

Signed

Figure BIO. Insulation radiant panel test data log format

39
APPENDIX C

STANDARD METHOD OF TEST FOR SMOLDERING

COMBUSTION CHARACTERISTICS OF MATERIALS

USED FOR THERMAL INSULATION

1. Scope

1.1 This method evaluates the tendency of thermal insulation in the form

of loose fill, batts or blankets to support smoldering combustion. It is

applicable to any insulation that is capable of being installed in the speciment holder at the density and in the physical state of the material in its

intended use.

1.2 The purpose of this test is to determine the tendency of the

material under test to support and propagate smoldering combustion subsequent

to exposure to a standard ignition source.

2. Summary of Method

2.1 This method measures the extent and progression of smoldering from

a lighted cigarette inserted vertically, with the lit end upward, into the

center of an insulation material sample.

2.2 The extent of damage to the test specimen, as indicated by percent

of specimen weight loss and by the extent of charring, are recorded in this

test, as well as any other observable combustion behavior, such as progression

to flaming combustion.

3. Significance

3.1 This method of test is designed to provide a basis for evaluating

the tendency of insulation to support smoldering combustion when subjected

to a small ignition source. The lighted cigarette represents a typical

ignition source which may make contact with insulation installed in

residential buildings.

4. Apparatus

4.1 Specimen Holder

4.1.1 The specimen holder shall be an open-top 20 + 0.2 cm square

box, 10 + 0.2 cm in height, fabricated from a single piece of 0.61 + 0.08 mm

thick (24 U.S. Standard gauge) stainless steel sheet with the vertical edges

of the box overlapped, not to exceed 7 mm in seam width, and soldered so as to be watertight.

4.1.2 The specimen holder during test use shall rest upon a pad

of inert insulation, such as of glass or ceramic fibers, of at least 2.5 cm

in thickness and approximating the dimensions of the bottom of the specimen

40
holder. The density of the insulation shall be 40 + 8 kg/m^. (Glass fiberboard which meets Federal Specification HH-I-558B, Form A, Class 1, plain

faced, is suitable for this purpose.)

4.2 Ignition Source

4.2.1 The ignition source shall be a cigarette without filter tip

made from natural tobacco, 85 + 2 mm long with a tobacco packing density of

0.270 + 0.020 g/cm^ and a total weight of 1.1 + 0.1 gm.

4.3 Balance

4.3.1 A balance of 1 kg capacity, accurate at least to 0.1 g, and

provided with a suitable scale pan is required.

4 . 4 Test Area

4.4.1 The test area shall be draft-protected and equipped with a suitable system for exhausting smoke and/or noxious gases produced by testing.

Air velocities as measured by a hot wire anemometer in the vicinity of the

surface of the sample shall not exceed 0.5 m/sec.

4.4.2 The test area shall be maintained at 21 + 3°C (70 + 5°F)

and 50+5 percent relative humidity.

4.3 Sampling

4.3.1 At least three samples shall be prepared of any material

undergoing test. Samples shall be taken in a manner to encompass possible

variations in material composition (for example, from the top, middle, and

bottom of bagged insulation)

4.3.2 Samples of material to be tested shall be selected, prepared,

and handled in a manner to avoid differences in the composition and condition

of the sample from that of the sampled material in its intended use.

5. Test Procedure

5.1 Samples and cigarettes shall be conditioned in air at a temperature

of 21 + 3°C (70 + 5°F) and a relative humidity of 50 + 5 percent for at least

48 hours prior to test. Samples and cigarettes shall be removed from any

packaging and exposed in a suitable manner to permit free movement of air

around them during conditioning.

5.2 Sample material shall be loaded into specimen holders to fill the

holders level and flush to the top edges of the holders. Specimen weight

shall be measured, at least to the nearest 0.2 g, by weighing the holder

before and after filling. The holder shall be tapped onto a solid surface

to induce settling and additional insulation shall be added and screeded flush

to the top edges of the holder to achieve the desired density. The density of

the specimen contained in a holder (volume 4000 cm^, 0.14 ft^) shall be

41
calculated and shall be tested at the settled density (Sec. 4.8.1 of

HH-I-515D)

5.3 With the sample in the holder and placed on the insulated pad, a rod of 8 mm diameter with a pointed end shall be inserted vertically into the

center of the material being tested and withdrawn to form an appropriate 85 mm

long cavity for the ignition source. A well lit cigarette, burned not more

than 8 mm (0.3 in), shall be inserted in the formed cavity, with the lit end

upward and flush with the sample surface.

5.4 Burning of the cigarette and specimen shall be allowed to proceed

undisturbed in the test area for at least 2 hours or until the smoldering is no longer progressing.

5.5 After completion of burning and after the holder has cooled down

to 25°C, the specimen holder with its material residue shall be weighed, at

least to the nearest 0.2 g, and the percent weight loss of the original

specimen calculated.^

5.6 After completion of burning, the minimum distance of charring or smoldering of the material from the edge of the holder shall be measured. In cases where the material tested has smoldered to some extent, the material

residue shall be carefully removed by layers and the closest proximity of

charred material to the vertical sides of the specimen holder determined to

the nearest 0.5 cm.

6. Criteria

6.1 Materials tested by this method shall be judged in terms of the

following criteria:

6.1.1 Weight loss of each specimen expressed as a percent of its

initial weight.

6.1.2 Evidence of flaming combustion of the specimen during testing.

7. Report

7.1 The report shall include the following:

7.1.1 Identification and/or description of the material being tested.

7.1.2 The original weight of specimens tested and their calculated

density.

7.1.3 The final weight of specimens tested and the percent weight

loss they have experienced during testing.

7.1.4 Any observations of the burning characteristics of the

specimens that could be pertinent to the material's performance in its

intended use. The weight of the cigarette residue is ignored in this exercise and may,

in some cases, result in a slight gain in sample weight.

42

1
NBS-1 14A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 78-1497

2. Gov’t Accession

No.

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

A PRELIMINARY STUDY OF THE FIRE SAFETY OF THERMAL

INSULATION FOR USE IN ATTICS OR ENCLOSED SPACES

IN RESIDENTIAL HOUSING

5. Publication Date July 1978

6. Performing Organization Code

7. AUTHOR(S)

Daniel Gross

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Wotk Unit No. 7500900

11. Contract /Grant No.

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

Same as No. 9

13. Type of Report & Period Covered

Final Report

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

bibliography or literature survey, mention it here.)

An evaluation was made of tne appropriateness of the flammability

requirements in Federal specifications for loose-fill cellulosic and mineral fiber insulation and mineral fiber batts and blankets. This includec

an analysis of currently used standard test methods for measuring insulation flammability or combustibility and their principle limitations. To

provide for more meaningful evaluations, a review was made of fire statistics and of likely fire occurrences, particularly for retrofit insulation in attic and enclosed spaces of residential buildings. A series of

laboratory tests was conducted using an attic floor radiant panel test

and a cigarette smoldering test to simulate flaming and smoldering exposures. Mockup tests on attic floor sections were conducted to validate

the extent of flame spread on attic insulation and the initiation of

smoldering ignition from covered recessed light fixtures. Based on these

tests, changes were recommended to Federal Specifications HH-I-515C,

j HH-I-521E and HH-I-1030A.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only ffie first letter of tfie ^st key word unless a proper name; separated by semicolons) Atticsj Federal Specifications, fire test,

flame spread; loose-fill; mineral fiber; residences;

smoldering; thermal insulation.

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(THIS REPORT)

21. NO. OF PAGES

1

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46

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