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NBSIR 81-2333

Reduced-Scale Modeling of

Mobile Home Fires: A Progress

Report

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

September 1 981

Interim Report

Issued December 1981

Sponsored principally by:

Division of Energy, Building Technology, and Standards

"^QC“"^«*^ffice of Policy Development and Research

J QQ

.S. Department of Housing and Urban Development

i/ashington, DC 20410

31-2333

1981

c, 2

NBSIR 81-2333

io 0 REDUCED-SCALE MODELING OF

MOBILE HOME FIRES: A PROGRESS

REPORT

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l.lUB AnY JAN 8 1982

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no. 21-

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David P. Klein

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

September 1981

Interim Report

Issued December 1981

Sponsored principally by:

Division of Energy, Building Technology, and Standards

Office of Policy Development and Research

U.S. Department of Housing and Urban Development

Washington, DC 20410

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
•• VSAt
TABLE OF CONTENTS

Page

LIST OF FIGURES iv

LIST OF TABLES . . vi

Abstract 1

1. INTRODUCTION 1

1.1 Objectives 2 1.2 Background 3

2. EXPERIMENTAL DETAILS 3

2.1 Use of Gas Burner 3 2.2 Experimental Approach 4 2.3 Full-Scale Test Unit 5 2.4 Quarter-Scale Model 6

2.5 Instrumentation 7 2.6 Exposure Fires 9 2.7 Test Criterion 10

3. RESULTS AND DISCUSSION H

3.1 Modeling Exposure Fires 11

3.2 Fire Growth and Interior Finish 13

3.3 Modifications 16

3.4 Relative Humidity and Repeatability .... 18

3.5 Single Room vs Entire Structure . 19

4. SUMMARY 20

5. ACKNOWLEDGMENTS 22

6. REFERENCES 2 3

iii
LIST OF FIGURES

Page

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Figure 11.

Figure 12.

Figure 13.

Photograph of single-wide mobile home used in

conducting full-scale fire tests 24

Plan view of full-scale mobile home 25

Drawing of wood wall and ceiling assembly of quarterscale enclosure showing key dimensions. Interior

finish materials, insulation, and exterior skin not

shown 26

Photograph illustrating wood wall and ceiling

assembly of quarter-scale enclosure. Northwest

corner is closest to camera 27

Plan view of full-scale bedroom illustrating sampling

locations for test measurements 28

Plan view of quarter-scale enclosure illustrating

sampling locations for test measurements 29

Temperature histories for two upholstered chairs

and three wood cribs of different sizes in the fullscale bedroom 30

Temperature histories for two wood cribs and a methane burner at two flow rates in the full-scale

bedroom . 31

Comparison of temperature histories sampled at

255 mm (full-scale) and 64 mm (quarter-scale) below

the ceiling for tests involving wood cribs in the

full-scale bedroom and tests with a methane burner

in the quarter-scale bedroom. All tests used noncontributing interior finish materials 32

Comparison of temperature histories measured at

25 mm (full-scale) and 6 mm (quarter-scale) below

the ceiling for tests involving wood cribs in the

full-scale bedroom and tests with a methane burner

in the quarter-scale bedroom. All tests involved

noncontributing interior finish materials 33

Temperature histories measured at 25 and 6 mm below

the ceiling in the center of the full-scale and

model bedrooms, respectively, for tests involving

lauan plywood walls and wood fiber ceilings .... 34

Temperature histories measured at 25 and 6 mm below

the ceiling in the center of the full-scale and

model bedrooms, respectively, for tests involving

lauan plywood walls and gypsum board ceilings ... 35

Temperature histories measured at 25 and 6 mm below

the ceiling in the center of the full-scale and

model bedrooms, respectively, for tests involving

noncontributing interior finish materials 36

IV
LIST OF FIGURES (Continued)

Page

Figure 14. Summary plot illustrating temperature histories

measured at 25 and 6 mm below the ceiling in the

center of the full-scale and model bedrooms,

respectively, for selected tests 37

Figure 15. Temperature histories for tests with lauan plywood

walls and gypsum board ceilings. A propane exposure

fire was used for test M4B 50. For the other tests

methane was used 38

Figure 16. Plan view of the original square burner and the

experimental triangular burner used in the model .... 39

Figure 17. Temperature histories for tests with lauan plywood

walls and gypsum board ceilings. The triangular

burner was used for test M4B 53. For the other tests

a square burner was used 40

Figure 18. Temperature histories illustrating the effect of the

experimental door opening for two combinations of

interior finish materials 41

Figure 19. Temperature histories for tests with lauan plywood

walls and gypsum board ceilings. For test M4B 58

the experimental door opening and triangular burner

were used. For the other tests the original door

opening and square burner were used 42

Figure 20. Temperature histories for two quarter-scale tests ... 43

Figure 21. Time to ignition of flashover indicators versus

ambient relative humidity for tests involving lauan

plywood walls, gypsum board ceilings, and low

intensity exposure fires 44

Figure 22. Time to ignition of flashover indicators versus

ambient relative humidity for tests involving lauan

plywood walls, gypsum board ceilings, and high

intensity exposure fires 45

Figure 23. Time to ignition of flashover indicators versus

ambient relative humidity for tests involving lauan

plywood walls, wood fiber ceilings, and high

intensity exposure fires 46

v
LIST OF TABLES

Page

Table 1. Design specifications for the wood cribs 47

Table 2. Description of interior finish materials used in

testing 48

Table 3. Summary information for tests using an upholstered

chair or wood crib as the exposure fire 49

Table 4. Summary information for selected tests using a methane

burner as the exposure fire 50

Table 5. Information on peak temperatures, heat flux levels,

and flashover times for tests using a high intensity

exposure fire 52

Table 6. Information on peak temperatures, heat flux levels,

and flashover times for tests using a low intensity

exposure fire 53

Table 7. Summary of time to reach flashover in full-scale

and time to reach 500°C or 375°C in model 54

Table 8. Average and peak temperatures measured at different

heights in the model for selected tests 55

Table 9. Minimum oxygen concentrations in bedroom doorway a,t floor level 56

Table 10. Minimum oxygen concentrations in living room doorway

at floor level 57

vi
REDUCED-SCALE MODELING OF MOBILE HOME FIRES:

A PROGRESS REPORT

David P. Klein

Abstract

A series of fire tests was conducted in the bedroom

of a single-wide mobile home and in a quarter-scale model

of that bedroom. The objectives of the tests were (1) to

evaluate the relationship between fire buildup in the

reduced-scale and full-scale enclosures and (2) to determine

the feasibility of using a reduced-scale model test to

assess the potential contribution of particular combinations of interior finish materials to fire growth in a mobile home.

The model tests simulated the phenomena of fire

growth and flashover, however the time to flashover

occurred later in the model than in the full-scale

bedroom. Flashover was taken as the time at which the

level of radiation at the center of the floor reached

2 W/cm 2

. Several modifications to the model were examined

but none adequately corrected the time delay to flashover.

However, by monitoring the upper air temperature in the

model, the occurrence or nonoccurrence of flashover for

corresponding full-scale tests could be reliably predicted. Therefore, the use of a quarter-scale model

was judged to be feasible.

Key words: Compartment fires; fire tests; flashovpr;

interior finish; mobile homes; models; room fires.

1. INTRODUCTION

A research project is ongoing at the Center for Fire Research (CFR) of

the National Bureau of Standards to evaluate the relationship between fire

buildup in a full-scale single-wide mobile home and fire buildup in a reducedscale enclosure. Full-scale testing has traditionally been used by CFR and

other research and testing organizations as a major tool for fire research

because it demonstrates realistic fire development under controlled environmental conditions. The primary efforts in full-scale testing to date can be

grouped into two general classes. First, full-scale fire testing is used to

provide comparative information regarding the performance of similar design

constructions with different interior finish, insulation, structural members,

or other features in order to assess the relative fire risk associated with

these features. Second, the results of full-scale fire tests are used to

identify the potential capabilities of standard laboratory fire tests to

provide information on material responses which qualitatively describe performance under full-scale conditions.

1
Full-scale testing is normally conducted under controlled conditions in

which ambient temperatures, initial ventilation, room geometry, and the size

and type of ignition source are held constant. However, due to the time and

expense involved with full-scale testing, it is usually not practical to

conduct many additional tests under different conditions and there is no

existing procedure to extend test results to cover other conditions.

It is felt that reduced-scale fire testing is a simpler, more versatile,

and more economical method by which the same information may be obtained as with full-scale testing. Because of the decreased time and expense involved

with reduced-scale testing, more tests can be conducted under a wider range

of conditions, allowing a more realistic evaluation of different design

features. A standardized reduced-scale fire test developed for laboratory

use would combine the best characteristics of both standardized laboratory

test methods and full-scale testing in that certain conditions could be held

constant for repeatability, yet a wide range of design features could be

assessed in an environment designed to examine not just a single material

response, but the full range of responses including all their interactions.

The purpose of this report is to describe the progress of the CFR

effort to model fire growth in a mobile home and to determine the feasibility

of a reduced-scale fire test.

1.1. Objectives

This project has three overall objectives:

1. To evaluate the relationship between fire buildup in

a reduced-scale and a full-scale enclosure.

2. To determine the feasibility of using a reduced-scale

model test to assess the potential contribution of

particular combinations of interior finish materials

to fire growth and spread in a full-scale mobile home.

3. To draft a proposed test method for a standardized

reduced-scale fire test if the use of a reducedscale model is found to be feasible.

This report deals with progress toward the first two objectives. If the

use of a reduced-scale model is determined to be feasible, a future report

will contain details of the proposed test method.

2
1.2 Background

In modeling research conducted at CFR, Parker and Lee [l]^ developed

scaling guidelines for designing reduced-size enclosures to model fire

buildup. These guidelines are:

1. All dimensions are proportional to the scale factor except:

a. the width of the doorway is proportional to the

square root of the scale factor, and

b. the thickness of the wall and ceiling materials

remains the same as full scale.

2. Fuel content and fuel surface area are proportional to the floor

area

3. The air supply rate is proportional to the floor area.

4. Time is the same in the model as in full-scale.

Using these guidelines, a quarter-scale (i.e., scale factor equals four)

model of the master bedroom was designed and constructed. The bedroom, because

of its relatively small size and high fire load, was judged to be the most

critical compartment in terms of fire growth in a mobile home.

2. EXPERIMENTAL DETAILS

2.1 Use of Gas Burner

During the course of previous research, a number of full-scale room

fire tests were conducted in various areas of a mobile home including the

bedroom [2] and living room [3,4]. One objective of these tests was to

determine the role of interior finish in fire growth in these rooms. Among

the items used as exposure fires to ignite the interior finish materials

were 16 kg (35 lb) upholstered chairs, and 13.6, 9.1, and 6.4 kg (30, 20,

and 14 lb) wood cribs. It was found during this work that for those tests

where upholstered chairs were used as the exposure fire, the initial fire

buildup varied considerably due to variation in the spread of flames along

the surfaces of the chairs. Since the ultimate objective of this modeling

1 Numbers in brackets refer to literature references at the end of this report.

3
project is to develop a proposed standardized test, it was deemed desirable

to use a more reproducible exposure fire in the quarter-scale enclosure.

Although fires from the wood cribs have been demonstrated to be more reproducible than fires from the upholstered chairs [5], fires produced by diffusion

gas burners provide even greater reproducibility than fires from wood cribs.

A diffusion gas burner is also more flexible since the flame from a single

burner can be adjusted to provide a wide range of heat production. In

addition, the heat produced by a burner can be precisely adjusted, which is

difficult to do with wood cribs. Finally, while wood cribs are susceptible

to variability in characteristics within the species of wood from which the

cribs are constructed, the variability in a gas burner is dependent only on the composition of the gas being burned and on the accuracy of the flow

metering equipment. Both the composition of the gas and the accuracy of the

flow meter can be ascertained and kept within acceptable limits. It was

decided for these reasons to use a diffusion gas burner in the quarter-scale

model to provide the exposure fire. See the appendix for the accuracy of the

flow meters used with the burner.

2.2 Experimental Approach

Once the decision had been made to use a diffusion gas burner, an experimental plan was developed to test and validate various aspects of the

quarter-scale model in relation to the full-scale room. This plan may be

viewed as a series of steps:

Step 1 : Tests had previously [2] been conducted in the full-scale

bedroom using combustible interior finish materials on the walls

and ceiling and using upholstered chairs to provide the exposure

fires. In order to determine the burning characteristics of the

exposure fires themselves (in addition to the burning characteristics

of wood crib exposure fires used in other mobile home testing)

tests were conducted in the full-scale bedroom using upholstered

chairs and the various size wood cribs with essentially noncontributing interior finish materials on the walls and ceiling. These

tests, the results of which are discussed in this report, demonstrated

that maximum upper air temperatures and heat flux levels on the floor

produced by a 16 kg upholstered chair were approximated by a 13.6 kg

wood crib, and that the intensity of both fires was approximately the

2 same . Therefore, the 13.6 kg wood crib was selected to approximate

the effects of a 16 kg upholstered chair for the purpose of developing

2

' Similar results were found in tests conducted in the living room [5].

4
a gas burner flame. Wood cribs weighing 9.1 and 6.4 kg were used to

provide supporting data at intermediate exposure levels. Although it

would have been technically easy to program the gas flow to duplicate

the shape of the temperature curves measured in the upholstered chair

tests, this was not considered a practical approach since the burning

rates of other chairs and combustible contents are not necessarily the

same and, in fact, are approximately constant in many cases.

S tep 2 : This step involved the development of standardized exposure

fires. To accomplish this, a 305 x 305 mm (12 x 12 in) gas burner

in the full-scale bedroom with noncontributing interior finish

materials was used to determine the burner flows whose temperature

curves matched those of the 6.4 and 9.1 kg wood cribs. These burner

flows were to be used later in tests with combustible interior finish

materials on the walls and ceiling.

Step 3 : Next, scaled burner flows were tested in the quarter-scale

model using noncontributing interior finish materials. The results

showed acceptable agreement with the full-scale tests. In addition,

a burner flow for the model was developed to correspond with the

results of the 13.6 kg wood crib when tested in the full-scale room.

S tep 4 ; The next step was to test the quarter-scale model using the

burner flows determined in steps 2 and 3 but with combustible interior

finish materials on the walls and ceiling. The materials chosen were

the same or similar to those materials used in the previous full-scale

testing in the bedroom.

Step 5 : Finally, the materials used in the model were tested in

the full-scale bedroom using burner flows corresponding to those

used in the model. This step was to determine how accurately and

in what ways the quarter-scale model could be used to predict fire

growth in the full-scale room.

2.3 Full-Scale Test Unit

3 The full-scale tests were conducted in the master bedroom (bedroom #1)

of a conventional three-bedroom single-wide mobile home (see figures 1 and 2)

3 Hereafter referred to as the bedroom.

5
4 The mobile home was approximately 3.7 x 18.3 m (12 x 60 ft) ; the bedroom was

approximately 3.5 m (11 ft 4 in) wide and 2.8 m (9 ft 2 in) long, resulting

in a floor area of 9.8 m

2 (105 ft 2 ), and had a ceiling height of 2.1 m (7 ft).

The single opening into the bedroom was through a doorway 735 mm (29 in) wide

and 2.0 m (6 ft 8 in) high, connecting the bedroom with the corridor. The

exposure fire was located in the southeast corner of the bedroom, which is the

corner diagonally opposite the doorway.

The mobile home had exterior walls constructed of 51 x 76 mm (2 x 3 in)

nominal thickness wood studs, spaced 405 mm (16 in) on center, with 76 mm

(3 in) of glass fiber insulation between the studs and the aluminum exterior

siding. The interior walls were constructed with nominal 51 x 51 mm (2x2 in)

studs, 405 mm (16 in) on center, with no insulation between the studs. The

roof construction included aluminum exterior sheeting attached mechanically

to a system of wood bow-string trusses, spaced 405 mm (16 in) on center, with

76 mm (3 in) of glass fiber insulation. The floor was constructed of 19 mm

(0.75 in) thick particle board. The bedroom had two 660 x 760 mm (26 x 30 in)

windows, located in the south and west walls. These windows were kept closed

during testing. A detailed plan view of the mobile home is shown in figure 2.

A sprinkler system was installed with small orifice open sprinkler heads

located in the center of the bedroom and in the corridor midtoay between the

bedroom and living room. The system was available for manual activation to

minimize fire spread outside the bedroom.

The interior finish materials were fastened with nails to the studs on

the walls and the ceiling trusses in accordance with recommended practices.

Assembly was completed at least 48 hours prior to the start of each test to

allow time for all elements to reach temperature and moisture equilibrium.

2.4 Quarter-Scale Model

The 1/4-scale model of the mobile home bedroom was constructed of

materials similar to the full-scale room itself. The interior dimensions of

the model were 0.88 x 0.70 x 0.55 m (34-1/2 x 27-3/4 x 21-1/2 in), not

including interior finish. The three exterior walls were constructed of

38 x 76 mm (1-1/2 x 3 in) wood studs, approximately 405 mm (16 in) on center

where possible, with 76 mm (3 in) of glass fiber insulation and a sheet metal

exterior. The wall representing an interior wall (i.e., the wall containing _ —

Values expressed in traditional units are exact. Values expressed m metric

units may be approximations. Lengths over 100 mm are always rounded to the

nearest 5 mm.

6
the doorway) was constructed with nominal 51 x 51 mm (2x2 in) studs with

no insulation between the studs, but with a piece of 4 mm (5/32 in) lauan

plywood on the exterior side to represent the adjoining interior wall. The

roof consisted of a sheet metal exterior with a wooden simulated truss system

(each section was cut from a single piece of wood), and 76 mm (3 in) of glass

fiber insulation. As in the full-scale unit, there was an open area between

the upper side of the insulation material and the sheet metal exterior skin.

The interior finish materials were attached with nails to the studs of the

walls and ceiling in a similar fashion to the full-scale room.

The walls and ceiling were placed on, but not permanently attached to,

a portable bench. In this way the entire unit could easily be moved. The top

surface of the bench, which constituted the floor of the enclosure, consisted

of 13 mm (1/2 in) inorganic calcium silicate marine board over 13 mm (1/2 in)

plywood. The floor area of the enclosure was 0.62 m

2 (957 in 2 ), approximately

one sixteenth the area of the full-scale room. The doorway opening was

370 x 510 mm (14-1/2 x 20 in) . As in the full-scale room, the exposure fire

was located in the corner opposite the door. Figure 3 shows details of the

enclosure. Figure 4 shows the wood framework of the walls and ceiling assembly

during construction.

After the model had been constructed and was in use, the typical time

required for one technician to reinstall the interior finish, insulation,

and any damaged studding was approximately two days. Therefore, it was

estimated that up to five tests could be conducted in the model every two

weeks, if necessary.

2.5 Instrumentation

Diagrams illustrating the locations where test measurements were taken

are shown for the full-scale room in figure 5 and for the quarter-scale model

in figure 6. The limits of error for the instrumentation are listed in the

appendix. Thermocouple trees, each consisting of six 0.91 mm (0.0359 in,

20 gauge) chromel and alumel wires packed in mineral insulation and enclosed

in a 3.15 mm (0.124 in) diameter inconel 702 sheath with a grounded junction,

were located in the center and doorway of both enclosures. The heights of the

thermocouples in the center of the full-scale room were 25, 255, 815, 1220, and

1675 mm (1, 10, 32, 48, and 66 in) below the ceiling and 25 mm (1 in) above the

floor. The corresponding heights in the model were 6, 64, 205, 305 and 420 mm

(0.25, 2.5, 8.0, 12.0, and 16.5 in) below the ceiling and 3 mm (0.125 in) above

the floor. The heights of the thermocouples in the doorway of the full-scale

room were 125, 405, 710, 1015, 1420, and 1830 mm (5, 16, 28, 40, 56, and 72 in)

7
below the lintel (i.e., below the top of the door opening). The corresponding

heights for the model were 32, 100, 180, 255, 355, and 455 mm (1.25, 4.0, 7.0,

10.0, 14.0, and 18.0 in) below the lintel. A 0.05 mm (0.002 in) diameter

chromel and alumel thermocouple insulated with glass fiber was located in the

center of the full-scale enclosure 25 mm (1 in) below the ceiling and in the

model 64 mm (2.5 in) below the ceiling.

Oxygen concentrations were sampled in the doorway of the full-scale room

at distances of 125, 405, 710, 1420, and 1880 mm (5, 16, 28, 56, and 74 in)

below the lintel. The distance of 1880 mm below the lintel is approximately

150 mm (6 in) above the floor. In the doorway of the model, oxygen concentrations were sampled at distances of 32, 100, and 180 mm (1.25, 4.0, and 7.0 in)

below the lintel and 32 mm (1.25 in) above the floor. In addition, a sample

was taken in the center of the quarter-scale enclosure at 380 mm (15 in) above

the floor. All samples were filtered through glass fiber to remove soot and

particulate matter, chilled through an ice bath to remove condensable vapors,

then filtered through anhydrous calcium sulfate to remove additional water,

and filtered through sodium hydroxide dispersed on a fiber base to remove

carbon dioxide. The samples were then passed through electro chemical oxygen

cells

In both the full-scale room and in the model, calibrated, water-cooled

Gardon-type heat flux transducers were used to measure total incident heat

flux at the floor in the center of the enclosure and at the doorway, at the

ceiling directly above the exposure fire, and on the east wall adjacent to

the exposure fire at 915 and 1830 mm (3 and 6 ft) above the floor in the

full-scale room and 265 and 455 mm (10.5 and 18.0 in) above the floor in

the model.

In addition to the heat flux transducer located at the floor in the

center of each enclosure, pieces of crumpled newsprint were placed on the

floor to serve as visual ignition indicators.

During certain tests of the model, some of the lower thermocouples

in the center of the enclosure were moved to different positions to monitor

air temperatures at various heights. In addition, for certain tests a second 0.05 mm (0.002 in) diameter thermocouple was included 6 mm (0.25 in)

below the ceiling.

8
2.6 Exposure Fires

The exposure fires in the full-scale room were produced using upholstered

chairs, various size wood cribs, and a gas burner. The upholstered chairs

weighed approximately 16 kg (35 lb) and each was constructed of a wood frame

with polyurethane foam and cotton batting, and covered with rayon fabric.

The removable seat cushion was also polyurethane foam covered with rayon

fabric. The chairs were stored in a test building until their weight

stabilized. Temperature and relative humidity in the test building were

maintained at 24 + 2.8°C (75 + 5°F) and 35 + 10%, respectively. They were

similar to chairs used in the full-scale tests previously conducted in the

bedroom. The two chairs tested were both of the same design and were produced

by the same manufacturer.

The wood cribs consisted of pieces of hemlock arranged in layers, with

each layer placed at a right angle to the previous one. In addition, two

bottom layers of two sticks each were included to support the crib above a pan containing 150 ml of heptane. The cribs were conditioned at 21°C (70°F)

and 50% relative humidity until the moisture content and the resulting change

in weight had stabilized. Cribs weighing 6.4, 9.1, and 13.6 kg (14, 20, and

30 lb) were used. The cribs were designed so that after conditioning their

weight would be at least as great as the weight specified. Final weight

adjustments could then be made by removing one or more sticks from the top.

Design specifications for the cribs are shown in table 1.

The gas burner used in the full-scale room consisted of a steel box

with a 305 x 305 mm (12 x 12 in) mineral wool cover. The top surface of the

burner was located approximately 305 mm above the floor. The burner used in

the model was geometrically scaled down by a factor of four, so that the top

surface was 76 x 76 mm (3x3 in) and had an area one-sixteenth that of the

large burner. The top surface of the reduced-scale burner was located 76 mm

above the floor. Because the scale factor was four, the ratio of corresponding

heat release rates between the large and small burner was 16 to 1. That is,

in order to model a particular full-scale exposure fire in the model, the

small burner would be adjusted to provide one-sixteenth the heat release rate

of the large burner. The gas used in the burners was methane, although a small number of comparison tests were conducted using propane.

9
2.7 Test Criterion

During previous research in mobile homes [2,3,4] it was determined that

flashover, or full room involvement, was a critical stage in fire growth in

a mobile home. Flashover is defined as a fire phenomenon in which the radiation from the heated upper walls and ceiling and from the hot gases and smoke

layer in the upper part of the enclosure is sufficient to cause ignition and

rapid, complete fire involvement of all combustible materials in the enclosure.

Flashover occurs when the total incident heat flux at the floor exceeds approximately 2 W/cm 2

. This corresponds to an upper air temperature of approximately

600°C.

During those tests in which flashover occurred in the living room or

bedroom, the levels of temperature, oxygen depletion, and carbon monoxide

established as limits for occupant incipient incapacitation’’ were exceeded

at the opposite end of the full-scale mobile home at approximately the time

of flashover. For those tests in which flashover did not occur, limiting

conditions generally either did not occur, barely exceeded limiting thresholds,

or exceeded limiting thresholds only after a relatively long period of time^.

This indicated that information about life safety conditions at the far end of

the mobile home could be deduced by knowing whether or not flashover occurred

in the room of fire origin. In addition, flashover marked the point at which

fire damage to the mobile home became severe. Therefore, the attainment of

flashover was chosen as the principal test criterion.

Because the objective of the quarter-scale model is to predict fire

growth in a full-scale mobile home it was anticipated that the attainment of

flashover, as determined by the exceeding of a certain upper air temperature

or by the exceeding of a critical heat flux on the floor, could also be used

as the test criterion for the model. It remained necessary, though, to demonstrate that combinations of interior finish materials which resulted in flashover in the full-scale room also resulted in flashover in the model when tested

with an equivalent scaled exposure fire, and combinations of interior finish

materials that did not result in flashover in the full-scale room did not

result in flashover in the model.

See reference [2] for a detailed discussion of these limits.

For a summary of the times at which limiting conditions were exceeded

during the previous series of bedroom tests, see figure 16 of reference [2].

10
3. RESULTS AND DISCUSSION

Summary information for the full-scale and reduced-scale tests is

listed in tables 2, 3, and 4. Table 2 contains information on the interior

finish materials used to line the walls and ceiling of the full-scale and

model enclosures. Included in this table is the surface flame spread

rating for each material as determined by the ASTM E 84 Tunnel Test [6],

Table 3 summarizes information about those tests for which an upholstered

chair or a wood crib was used as the exposure fire. The table lists the

interior finish materials, type of exposure fire, maximum temperatures,

maximum total incident heat flux, and time to flashover for each test. The

temperatures were measured 255 mm (10 in) below the ceiling in the center of

the room. The heat flux was measured at the floor in the center of the room.

Table 4 summarizes information about those tests for which a methane gas

burner was used as the exposure fire. This table includes the interior

finish materials, flow rate to the burner, heat output of the burner, and

time to flashover.

3.1 Modeling Exposure Fires

As mentioned previously, a series of tests was conducted in the fullscale bedroom using essentially noncontributing interior finish materials

in order to gain information about the fires produced by upholstered chairs

and various size wood cribs without contribution from other combustibles.

For these tests the walls and ceiling of the bedroom were lined with 13 mm

(0.5 in) thick unpainted, paper-faced gypsum board. In the corner with the

exposure fires, additional protection was provided with 13 mm (0.5 in) thick

inorganic calcium silicate marine board which extended 1.2 m (4 ft) from the

corner on both walls from floor to ceiling, and covered a 3 m

2 (32 ft 2

) area

of the ceiling in the corner. Since none of the fires ever extended beyond

the area of the corner protected by the marine board, the walls and ceiling

for all practical purposes did not contribute to the fires.

This series of tests involved two 16 kg (35 lb) upholstered chairs and

6.4, 9.1, and 13.6 kg (14, 20, and 30 lb) wood cribs. Figure 7 shows the

temperature histories of these five items in the full-scale bedroom. In

this case the temperatures were measured 255 mm (10 in) below the ceiling

in the center of the room. As can be seen, the maximum temperatures attained

by the upholstered chairs were roughly approximated by the 13.6 kg (30 lb)

wood crib, although the temperature curves of the upholstered chairs show

significant peaks while the curves produced by the wood cribs were considerably smoother and generally higher. Maximum total incident heat flux levels

11
(see table 3) were also similar for the 13.6 kg crib and the upholstered

chairs. Results similar to these were obtained in tests involving the same

types of fires conducted in the mobile home living room, which was also lined

with noncontributing interior finish materials [5]. As mentioned previously,

the temperature curve of the 13.6 kg wood crib rather than the curves of the

upholstered chairs was used in developing the gas burner flow since the burning

rates of other chairs and combustible contents may be different and in many

cases are approximately constant.

The next series of full-scale tests was conducted to attempt to approximate gas burner. After some experimentation, reasonable approximations were

obtained for the 6.4 and 9.1 kg (14 and 20 lb) cribs. Figure 8 illustrates

these approximations.

At this point testing was begun in the quarter-scale enclosure to attempt

to model the temperature histories of the wood cribs using the reduced-scale

burner with scaled down methane flow rates. The area of the burner and the

flow rates were both scaled down by a factor of 16 (the square of the scaling

factor) . Figure 9 shows a comparison of the temperature histories of the

fires with the wood cribs in the full-scale bedroom and selected tests

involving various gas flow rates in the quarter-scale model.

All the temperature comparisons made up to this point were measured

255 and 64 mm (10 and 2.5 in) below the ceiling for the full-scale room and

model, respectively. However, later analysis suggested that, because higher

temperatures existed closer to the ceiling in the full-scale room, comparisons

at 25 and 6 mm (1.0 and 0.25 in) for the full-scale room and the model,

respectively, might be more appropriate. Therefore, for the later tests

involving combustible interior finish, the comparisons were made at those

distances. However, it was necessary to confirm that the burner flows

previously developed, which were based on temperature comparisons measured

at 255 and 64 mm below the ceiling, were still valid when the comparisons

were made for temperatures measured at 25 and 6 mm below the ceiling. Figure

10 shows a comparison of the temperature histories measured 25 and 6 mm below

the ceiling for the full-scale and model tests shown in figure 9. Although

the agreement was not as close for the temperatures at these distances, the

agreement was judged close enough so that the development of new burner flows

was not required.

12
3.2 Fire Growth and Interior Finish

The next phase of work involved tests which were conducted with various

combinations of interior finish materials on the walls and ceiling using

different exposure fires (different burner intensities) . For the purpose of

analysis, the tests run with two specific sets of burner intensities were

studied. For the high intensity fires the methane flow was 14.06 m

3 /hr

(497 ft 3 /hr) for the full-scale burner and 0.88 m

3 /hr (31 ft 3 /hr) for the

quarter-scale burner. These flows produced 147.3 and 9.2 kW (8,382 and 524

Btu/min) in the full-scale room and model, respectively. For the low intensity

fires the methane flow was 8.02 m

3 /hr (284 ft 3 /hr) full-scale and 0.50 m

3 /hr

(18 ft 3 /hr) quarter-scale, which produced 84.1 and 5.2 kW (4,783 and 296

Btu/min) full-scale and quarter-scale, respectively. The set of high intensity

fires represented a 13.6 kg (30 lb) wood crib under full-scale and quarterscale conditions and could be related to the 16 kg (35 lb) upholstered chair.

The set of low intensity fires represented a 6.4 kg (14 lb) wood crib under

full-scale and quarter-scale conditions.

Figures 11, 12, and 13 show temperature histories measured 25 and 6 mm

(1.0 and 0.25 in) below the ceiling in the center of the full-scale and model

bedrooms for three combinations of interior finish materials with high

intensity and low intensity exposure fires. The tests shown in figures 11(a)

and 11(b) each involved 4 mm (5/32 in) lauan plywood walls and a 13 mm (1/2 in)

wood fiber ceiling. Of the materials tested, these interior finish materials

constituted the most severe combination in terms of fire growth and spread.

The tests shown in figures 12(a) and 12(b) each involved 4 mm (5/32 in) lauan

plywood walls with a 10 mm (3/8 in) gypsum board ceiling. And those tests

shown in figures 13(a) and 13(b) each involved 13 mm (1/2 in) marine board

walls and ceiling (marine board over gypsum board in the full-scale tests)

Of the three combinations, this was the least severe in terms of fire growth

and spread. For ease in viewing, the trends shown in figures 11, 12 and 13

have been summarized in figure 14. This figure illustrates temperature

histories for one full-scale and one representative model test under low

intensity and high intensity exposure fires for each of the three combinations

of interior finish materials.

Flashover, as previously defined, has been shown to occur when the total

incident heat flux at the floor exceeds approximately 2 W/cm 2 [2,3]. For each

of the tests conducted, if a combination of interior finish materials produced

flashover when tested in the full-scale room, then that same combination of

materials when tested in the model with a scaled burner intensity also produced flashover. And if a particular combination did not produce flashover

13
in the full-scale room, the combination did not produce flashover in the model

with a scaled burner intensity. Thus, the most important test of the model,

the ability to predict flashover in the full-scale room, appears to have been

met.

It has been demonstrated that when flashover occurs in a room, the upper

air temperature exceeds approximately 600°C [2,3]. However, the attainment of

600°C does not necessarily signify the beginning of flashover. As can be seen

in figures 11 and 12, flashover in the quarter-scale tests occurred at some

period of time after the attainment of 600°C. In fact, during several quarterscale tests the temperature reached an initial peak greater than 600°C, fell

back to a lower temperature, and later increased past 600°C again at which

time flashover (as signaled by the exceeding of 2 W/cm 2 on the floor) was

observed. As the severity of the wall/ceiling combination and exposure fire

decreased, the length of time and range of times for flashover to occur in

the model increased. Thus, while the times to 2 W/cm 2 were relatively close

between the model and the full-scale room for the severe condition of plywood

walls, wood fiber ceiling, and high burner intensity; under the condition of

plywood walls, gypsum board ceiling, and low burner intensity the time to

2 W/cm 2 was 151 sec for the full-scale test but ranged from 460 sec to 972 sec

for the model.

The wide range of times to the attainment of 2 W/cm 2 on the floor and

the phenomenon of an initial peak temperature followed by a decrease or plateau

indicated that the interior finish materials in the model did not always provide enough fuel to lead to rapid flashover. Rather, it appeared that the

time of the initial peak temperature indicated when most of the easily consumed

fuel became exhausted, after which the fires died back until the walls and

ceiling had dried out enough to become further involved. This theory is

supported by the apparently significant influence of relative humidity on

the times required to reach flashover (see section 3.4). In addition, the

greater heat loss by convection in the model and the differences in stoichiometry and mixing between the full-scale and the model may have contributed to

the difference in performance between the full-scale and the model.

This performance indicated that the model provided a less severe test

than the full-scale room and that the model performed better when the

conditions being tested (i.e., interior finish materials and exposure fire)

were more severe. This also indicated that, if the attainment of 2 W/cm 2 heat flux on the floor was taken to be the indication of flashover, then some

conditions which might be considered "border-line cases" might require an exceedingly lengthy period of time to reach flashover in the model (or might

14
never reach flashover under high humidity conditions) but might attain

flashover in a full-scale test. For this reason it was decided to make use

of the initial peak temperature which occurred in those tests which attained

a delayed flashover.

Tables 5 and 6 summarize peak temperatures, times to peak temperatures,

times to the attainment of 2 W/cm 2 on the floor, and times to ignition of the

first newsprint indicator for all tests having high and low burner intensities

respectively. In every test of the model which involved a high burner

intensity and in which a delayed flashover was attained, the initial peak

temperature 6 mm (0.25 in) below the ceiling in the center of the room reached

at least 515°C. In those tests which involved a high burner intensity and in

which flashover was not attained, there was generally no pronounced initial

peak temperature and, regardless of the occurrence of a peak, the temperature

7

6 mm (0.25 in) below the ceiling did not exceed 431°C . This indicated that

the initial peak temperature could be used to predict the potential for flashover given the proper environmental conditions, and that a temperature greater

than 431°C but less than 515°C could be chosen as a criterion for those tests

using a high burner intensity. The temperature of 500°C was chosen as a temperature which would likely be exceeded during tests which would eventually

attain flashover but which would likely not be exceeded during tests which

would not eventually attain flashover. For those tests involving a low burner

intensity 375°C was chosen to be a reasonable criterion. It can be seen in

figures 11, 12, and 13 that, of the interior finish combinations tested, only

the combinations of gypsum board or marine board on the walls and ceiling did

not exceed 500°C and 375°C for high-intensity and low-intensity tests,

respectively.

Table 7 summarizes information from tables 4, 5, and 6. This information

provides a comparison between the time to reach flashover (2 W/cm 2

) for a full

scale test and the times to reach 500°C or 375°C for corresponding reducedscale tests. Table 7 shows that the times to reach 500°C and 375°C in the

model are much closer to the time to flashover in the full-scale than the

times to actually reach flashover in the model. Table 7 also shows that the

time to reach flashover is subject to some variability. Relying on the flashIn two tests (tests M4B 43 and 47) involving nonstandard interior finish

(gypsum board walls and a wood fiber ceiling) , the initial peak temperature

was 520 and 569°C, respectively. In both tests the upper air temperature

exceeded 600°C and although the incident heat flux on the floor was

noticeably higher (0.89 and 1.40 W/cm 2

, respectively) than usually occurs

in non flashover tests, it never reached 2 W/cm 2

. These tests were judged

to have reached flashover based on the upper air temperatures exceeding

600 °C

15
over time for a single test may be misleading. The performance of the newsprint flashover indicators is illustrated in tables 5 and 6. These tables

show that in most cases the time to ignition of the first newsprint indicator

was very close to the time to attain 2 W/cm 2 on the floor, indicating that

generally the newsprint provided a good indication of the occurrence of flashover.

3.3 Modifications

Several modifications to the model were examined in an effort to reduce

the time to delayed flashover in the model and to bring temperature histories

in the model closer to their corresponding temperature histories for full-scale

tests. The modifications to the model included (1) the use of propane, rather

than methane, as the burner fuel, (2) the use of a burner designed to increase

the flame exposure to the walls, and (3) the use of a lower, wider door opening.

In addition, the use of temperatures measured at a distance other than 6 mm

below the ceiling was investigated.

The first modification which was tested was the use of propane, rather

than methane, as the burner fuel. Because propane has a more radiant flame,

it might be expected to cause the combustible interior finish materials to

become involved sooner. Although a propane flame would also affect fire

growth in the full-scale room, it was thought that its use might bring the

time to flashover in the model closer to the time to flashover in the fullscale room, particularly for less flammable interior finish and lower burner

intensities. Figure 15 illustrates temperature histories for a full-scale

test and four quarter-scale tests all involving the same lauan plywood walls

and gypsum board ceiling and each with a low-intensity (5.2 kW) exposure fire.

Test M4B 50 involved a propane flame, methane was used for the other tests.

The propane flame produced somewhat higher temperatures than the methane flames

in the other quarter-scale tests and resulted in flashover in the shortest

time. However the results were not a dramatic improvement and the shortened

time may have been influenced by the lower ambient relative humidity.

The next modification examined was the use of a redesigned burner. The

full-scale and reduced-scale burners were both designed with square burning

surfaces since the wood cribs had square burning surfaces (refer to section

2.6). As a means of involving more surface area of the walls in the model a burner was designed whose burning surface contained the same area as the

quarter-scale burner but whose burning surface was in the shape of a right

isosceles triangle (see figure 16) . Since the burner area and gas flow rate

were not changed the exit velocity remained the same. However, because the

16
exposed wall area was increased and because the flame stayed closer to the wall

surfaces and therefore provided improved heat transfer, it was thought that a shorter time to flashover might result. Figure 17 illustrates temperature

histories for a full-scale test and three quarter-scale tests, all involving

the same lauan plywood walls and gypsum board ceiling. One of the quarterscale tests (test M4B 53) used the triangular burner, the other two used the

square burner. Test M4B 53 experienced a lower initial peak temperature than

the other two model tests but reached flashover first. However, because of

the lower ambient relative humidity for that test, it is not clear that the

more rapid time to flashover was primarily the result of the triangular

burner. In addition, the burner did not eliminate the phenomenon of the

initial peak temperature followed by a decline.

In order to trap more hot gases in the upper part of the room the top

of the door opening (the lintel) was lowered for several tests. To maintain

g a constant ventilation parameter the width of the opening was increased.

The dimensions of the experimental door opening were 430 mm (17 in) wide by

455 mm (18 in) high. The dimensions of the original opening were 370 mm

(14.5 in) wide by 510 mm (20 in) high. Figures 18(a) and 18(b) illustrate

temperature histories for tests with the high burner intensity and involving

lauan plywood walls with gypsum board and wood fiber ceilings, respectively.

With the exception of test M4B 57, the quarter-scale tests in each group

which had the experimental door opening experienced slightly lower temperatures

during the initial buildup phase and had a lower initial peak temperature

than the other quarter-scale tests. In addition, the experimental door

opening did not appear to decrease the time to delayed flashover.

For test M4B 58 the experimental burner and experimental door opening

were used together. Figure 19 illustrates temperature histories for this

test and other tests using similar interior finish materials and the high

burner intensity. For test M4B 58 the plateau temperature remained relatively

high compared with the temperatures produced in the other model tests.

However, the time to flashover was still not significantly improved.

Beginning with test M4B 50, temperatures in the center of the model

enclosure were measured at 13 and 25 mm (0.5 and 1 in) below the ceiling in

addition to 6 mm (0.25 in) below the ceiling. This was done to determine

whether the temperatures being measured 6 mm down were actually the peak

temperatures. Figure 20 shows temperature histories at these three elevations

8 q / O The ventilation parameter for open doorways is proportional to wh

where w and h are the width and height of the doorway, respectively. See

reference [1] for a further discussion.

17
from two typical tests. Table 8 provides more detailed information on temperatures measured at the three distances for tests M4B 50 through 60. In 8 of

9 the 11 tests examined, the highest average temperature occurred 25 mm below

the ceiling (shown as "Position C" in table 8) . This occurred in 3 of the

5 tests using the original door opening and in 5 of the 6 tests using the

experimental opening. The peak temperature monitored inside the enclosure was

measured at 25 mm below the ceiling in 9 of the 11 tests. This occurred in

4 of the 5 tests using the original door opening and in 5 of the 6 tests using

the experimental opening. In those cases where the peak measured temperature

or peak measured average temperature did not occur at 25 mm below the ceiling,

the peaks occurred at 13 mm down. The temperatures measured 6 mm below the

ceiling were always the lowest of the three, due to heat losses to the

ceiling or outgassing. Table 8 indicates that, although the height at which

the true peak temperature actually occurs may vary, the true peak is more

likely to be measured at 25 mm than 13 mm and much more likely to be measured

at either 25 or 13 mm than at 6 mm.

3.4 Relative Humidity and Repeatability

Figures 21, 22, and 23 illustrate the relationship between ambient

relative humidity and the time to reach ignition of flashover indicators in

the model for three combinations of interior finish materials and exposure

fires. Figure 21 involves tests with lauan plywood walls, a gypsum board

ceiling, and a low intensity (5.2 kW) exposure fire. Figure 22 involves the

same lauan plywood walls and gypsum board ceiling but with a high intensity

(9.2 kW) exposure fire. This represents a more severe test condition. The

general trend in these two figures of increased ignition times with increased

ambient relative humidity suggests that the humidity has an effect on the

time to reach ignition of the indicators. Figure 23 involves tests with lauan

plywood walls, a wood fiber ceiling, and a high intensity burner. This

represents the most severe test condition of the three. For these tests any

effect due to relative humidity appears to be imperceptible.

If curves were to be fit to these sets of points the curves would

provide a basis for defining the repeatability of the model, at least in

terms of time to flashover, by the scatter of the points around the curves.

And by experimentally collecting points at the extreme ends of the curves,

limiting conditions might be extrapolated (e.g., the minimum time to flashover

for a "no humidity" condition and the humidity level, if one exists, at which

flashover will not occur for a given combination of interior finish materials

and exposure fire)

__ — - The average temperature for each location is determined by summing the

temperature values read every 10 seconds and then dividing by the number of

values read. 18
3.5 Single Room vs Entire Structure

Several questions arise in regard to using a model of one room as opposed to a model of the entire structure. One question concerns the

adequacy of using a single-room model to test interior finish materials

which may be used throughout the mobile home. Another question concerns

which room should be chosen to be modeled.

In regard to the first question, the use of a single-room model is

valid if it can be shown that test results using this model will predict

full-scale test results using the entire structure. As discussed in

section 2.7 and references [2,3, and 4], the attainment of flashover in the

fire room can be used to deduce information relating to both the life safety

conditions at the far end of the full-scale mobile home and the fire damage

to the mobile home. It is for this reason that the attainment of flashover

in the fire room was selected as the test criterion for the full-scale tests

referenced above and for use in this modeling work. But since the attainment

of flashover is all that is required, data and observations from other parts

of the full-scale mobile home are not necessary. This means that it only

needs to be shown that test results (i.e., whether or not combinations of

interior finish materials attain flashover with particular exposure fires) in

the model will predict test results in the full-scale room. And in section

3.2 it was shown that, for the tests conducted to date, the use of 500°C and

375°C as test criteria for model tests using high-intensity and low-intensity

exposure fires, respectively, will predict the attainment of flashover in the

full-scale bedroom.

A related issue is whether the enclosed nature of a mobile home results

in an air supply to the fire which, after a period of time, contains significantly less oxygen resulting in a decrease in fire severity in the fullscale home. If this were the case, the fact that the air supply to the

model always contains the normal ambient concentration of oxygen would tend

to increase the relative severity of the model since the fire in the model

would always have an ample supply of oxygen. This issue is actually not a problem since the overall objective of predicting full-scale flashover using

the model appears to be possible. However, tables 9 and 10 show that the

depletion of oxygen in the return air entering the fire room in full-scale

tests is generally not great. Table 9 shows oxygen concentrations for air

at the floor level entering the bedroom door and table 10 shows similar

concentrations for tests conducted in the living room under a previous series

of tests (see reference [3]). For the bedroom under non-f lashover conditions,

even after 10 min (600 sec) the concentration never fell below 19.8%. In those

tests which reached flashover, the minimum pre-f lashover concentration never

19
fell below 19.5%. For the living room under non-f lashover conditions the

concentration never fell below 19.1%. In those tests which reached f lashover

the minimum pre-f lashover oxygen concentration in 3 of the 4 tests was 20.9%;

in the other test the minimum was 15.9%. It should be noted, however, that

any increase in fire severity in the model due to increased oxygen in the

air supply relative to the full-scale mobile home is beneficial since, as mentioned previously, the model is inherently less severe than the full-scale

test.

The second question regarding a single-room model concerns which room

of the mobile home should be modeled. This question has no one correct

answer. There is no reason to believe that the modeling techniques used

here for the bedroom could not also be used to model fire buildup in other

areas of a mobile home such as the living room or corridor. It should be

noted that as the size of the room increases, the relative severity of fire

growth in that room decreases. That is, a fire initiated by a 9.2 kW source

in the living room will be less severe than a fire initiated by the same

source burning in the bedroom. In this work the bedroom was modeled because

its smaller volume presented a more severe test for interior finish materials

4 . SUMMARY

This report details results from a number of tests conducted as part of

an effort to model fire growth in a mobile home and to determine the feasibility of a reduced-scale model room fire test. The objectives of this

modeling project are: 1) to evaluate the relationship between fire buildup

in a reduced-scale and full-scale enclosure, 2) to determine the feasibility

of using a reduced-scale model to assess the potential contribution of

combinations of interior finish materials to fire growth and spread in a full-scale mobile home, and 3) if the use of a reduced-scale model is found

to be feasible, to draft a proposed test method for a standardized reducedscale fire test. This report deals with progress toward the first two

objectives

Full-scale fire tests were conducted in the bedroom of 'an actual

single-wide mobile home. Reduced-scale fire tests were conducted in a quarter-scale model of that bedroom. The first phase of testing involved

noncontributing interior finish materials. The purpose of this testing

was to calibrate a full-size and quarter-scale methane diffusion burner for

the full-size room and model, respectively, to simulate the burning of 16 kg

(35 lb) upholstered chairs and 13.6, 9.1, and 6.4 kg (30, 20, and 14 lb) wood

cribs. The second phase of testing involved using the burners at specific

20
methane flows with various combinations of combustible interior finish

materials on the walls and ceiling to evaluate the relationship between fire

buildup in the quarter-scale and full-size rooms. The attainment of flashover

was selected as the test criterion for previous full-scale mobile home tests

and for these full-scale tests since flashover is a critical stage in fire

development and deductions about conditions at other locations in the mobile

home can be made by knowing whether or not flashover has occurred in the fire

room.

Based on the results of the tests conducted so far, it appears that the

quarter-scale model can be used to predict flashover in the full-scale bedroom

by the monitoring of upper air temperatures in the model. For quarter-scale

tests using an exposure fire which produced 9.2 kW (524 Btu/min) and fullscale tests using an exposure fire which produced 16 times as much heat

(corresponding to the square of the scaling factor 4) , when the air temperature

6 mm (0.25 in) below the ceiling in the model exceeded 500°C, flashover

occurred in the corresponding full-scale test. If the temperature in the

model did not exceed 500°C, flashover did not occur in the corresponding fullscale test. Similar results occurred when the exposure fire in the model

produced 5.2 kW (296 Btu/min), the full-scale exposure fire produced 16 times

as much heat, and the temperature of 375°C was used. Thus the flashover

prediction temperatures of 500 and 375°C in the model can be used as test

criteria for tests using 9.2 and 5.2 kW exposure fires, respectively.

The model was shown to simulate the basic phenomena of fire growth and

flashover. However flashover, as determined by the attainment of 2 W/cm 2 on the floor, occurred after a longer period of time in the model. Three

modifications to the model were tested in an effort to reduce the time delay

to flashover. These modifications were: 1) the use of propane, rather than

methane, as the burner fuel, 2) the use of a burner designed to increase the

flame exposure to the walls, and 3) the use of a lower, wider door opening to

trap more heated gas in the upper part of the enclosure. None of the modifications provided enough improvement to justify making it a permanent part of

the model. However, the delayed time to flashover (or even the possibility

of no flashover) in the model does not affect the accurac of the test since

the attainment of a particular flashover prediction temperature in the model

and not the attainment of flashover itself is the test criterion.

An examination of air temperatures at different heights in the model

indicated that temperatures measured at 13 and 25 mm (0.5 and 1 in) below the

ceiling were generally higher than the temperature at 6 mm (0.25 in) below the

ceiling. If temperatures were to be monitored at 13 or 25 mm rather than 6 mm,

21
the flashover prediction temperatures of 500 and 375°C would require upward

adjustment. This will be examined in a future report.

Ambient relative humidity apparently causes a delay in the time to reach

flashover in the model, particularly for less combustible interior finish

combinations and lower burner flows. A curve which is fit to the data points

would provide a basis for defining the repeatability of the model at least in

terms of time to reach flashover, and limiting conditions for the model might

be determined by extrapolating such a curve.

The technique of using a model of a single room to test interior finish

materials which may be used throughout an entire mobile home is valid since

it can be demonstrated that test results using the model will predict fullscale test results using the entire structure. There is no reason to believe

that the modeling techniques used here for the bedroom can not be applied to

any room of a mobile home. In this case the bedroom was selected since its

smaller volume makes the model a more severe test of interior finish materials

than if a larger volume room such as the living room were used.

In conclusion, it does appear to be feasible to assess the potential

contribution of interior finish materials to fire growth and spread in a full-scale mobile home through the use of a reduced-scale model. Therefore,

a proposed standardized test method developed around the quarter-scale model

described in this report will be drafted. Details of this proposed test

method and results from further testing will be included in a future report.

5 . ACKNOWLEDGMENTS

Appreciation is expressed to M. Womble for his assistance in the

preparation, instrumentation, scheduling, and conduct of the experimental

work; to W. Bailey, N. Breese, M. Gibb, R. Lawson, R. Lindauer, T. Maher,

O. Owens, S. Steel, R. Triplett, and C. Veirtz for their assistance in the

experimental work; and to W. Parker for his numerous helpful comments

throughout the project.

Some of the materials for use in this work were provided by Armstrong

World Industries, Inc. and the Hooker Chemicals and Plastics Corporation.

The project was sponsored in part by the Office of Policy Development

and Research, U.S. Department of Housing and Urban Development.

22
6 . REFERENCES

[1] Parker, W.J. and Lee, B.T., A Small-Scale Enclosure for Characterizing

the Fire Buildup Potential of a Room, Nat. Bur. Stand. (U.S.), NBSIR

75-710 (June 1975)

[2] Budnick, E.K., Klein, D.P., and O'Laughlin, R. , Mobile Home Bedroom

Fire Studies: The Role of Interior Finish, Nat. Bur. Stand. (U.S.),

NBSIR 78-1531 (Sept. 1978)

[3] Budnick, E.K., Mobile Home Living Room Fire Studies: The Role of

Interior Finish, Nat. Bur. Stand. (U.S.), NBSIR 78-1530 (Sept. 1978).

[4] Budnick, E.K. and Klein, D.P., Mobile Home Fire Studies: Summary and

Recommendations, Nat. Bur. Stand. (U.S.), NBSIR 79-1720 (Mar. 1979).

[5] Klein, D.P., Characteristics of Incidental Fires in the Living Room

of a Mobile Home, Nat. Bur. Stand. (U.S.), NBSIR 78-1522 (Sept. 1978).

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

Materials, 1979 Annual Book of ASTM Standards, Part 18, American

Society for Testing and Materials, Philadelphia (1979).

23
24

Figure

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26

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27
NORTH

Location B (Burner) Heat flux transducers:

East wall, 915 and 1830 mm above floor, horizontal view

Ceiling, centered over burner, downward view

Location C (Center)

Thermocouples: 25, 255, 815, 1220, and 1675 mm below ceiling,

25 mm above floor Heat flux transducer: floor level, upward view

Location D (Door)

Thermocouples: 125, 405, 710, 1015, 1420, and 1830 mm below lintel Heat flux transducer: floor level, upward view

Oxygen probes: 125, 405, 710, 1420, and 1880 mm below lintel

Figure 5. Plan view of full-scale bedroom illustrating

sampling locations for test measurements.

28
NORTH

Location B (Burner)

Heat flux transducers:

East wall, 265 and 455 mm above floor, horizontal view

Ceiling, centered over burner, downward view

Location C (Center)

Thermocouples: 6, 64, 205, 305, 420 mm below ceiling,

3 mm above floor

Heat flux transducer: floor level, upward view

Oxygen probe: 380 mm above floor

Location D (Door)

Thermocouples: 32, 100, 180, 255, 355, and

455 mm below lintel

Heat flux transducer: floor level, upward view

Oxygen probes: 32, 100, 1.80 mm below lintel,

32 mm above floor

Figure 6. Plan view of quarter-scale enclosure illustrating

sampling locations for test measurements.

29
ELAPSED

TIME

(MINUTES)

(o 03a) Haniradrm o a o d

a

d

id Ln cn <u -* (0 03Q) 3yniYd3dKQL

0)

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30
ELAPSED

TIME

(MINUTES)

(o 03a) 3aniYH3dn3L

o a o o o o

ID LD 'f CD C\J —

(o 03a) 3yniYy3dim

31

Figure

8.

Temperature

histories

for

two

wood

cribs

and

a

methane

burner

at

two

flow

rates

in

the

full-scale

bedroom.
ELAPSED

TIME

(MINUTES)

(o 33a) 3aniYH3dmL

DO

o

O

CM

ere

CO _

40 _

to _

cn _

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cn -

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O)

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(o 33a) 3yniYy3dh3i

32

Figure

9.

Comparison

of

temperature

histories

sampled

at

255

mm

(full-scale)

and

64

mm

(quarter-scale)

below

the

ceiling

for

tests

involving

wood

cribs

in

the

full-scale

bedroom

and

tests

with

a

methane

burner

in

the

quarter-scale

bedroom.

All

tests

used

noncontributing
ELAPSED

TIME

(MINUTES)

(0 33Q) 3yniYM3dri3L

DO

D o a

a

D o a o o O a cj CD CD o CD CD

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33
TEMPERATURE

(DEG

C)

TEMPERATURE

(DEG

C)

ELAPSED TIME (MIN) 0 1 2 3 4 5 6 7 8 9 10 1 1 12 13 1

15 1

1

18 120

ELAPSED TIME (SEC)

Figure 1 1 a. High intensity exposure fire.

ELAPSED TIME (MIN) 9 10 11 12 13 14 15 16 17 18 19 20

Figure 11b.

ELAPSED TIME (SEC)

Low intensity exposure fire.

Figure 11. Temperature histories measured at 25 and 6 mm below the ceiling in

the center of the full-scale and model bedrooms, respectively, for tests involving lauan plywood walls and wood fiber ceilings.

34

TEMPERATURE

(DEG

C)

TEMPERATURE

(DEG

C)
TEMPERATURE

(DEC

C)

TEMPERATURE

(DEC

C)

ELAPSED TIME (MIN)

0 1 2 3 4 5 6 7 B 9 ID 11 12 13 1 4 L 5 1 6 1 7 10 1 9 2D

Figure 12a. High intensity exposure fire.

ELAPSED TIME (MIN) D 1 2 3 4 S 6 7 B 9 ID 1 1 12 13 1 4 IS 1 6 1 7 IB 1 9 2D

Figure 12b. Low intensity exposure fire.

Figure 12. Temperature histories measured at 25 and 6 mm below the ceiling in the center of the full-scale and model bedrooms, respectively, for tests involving lauan plywood walls and gypsum board ceilings.

35

TEMPERATURE

(DEC

C)

TEMPERATURE

(DEG

C)
TEMPERATURE

(DEG

C)

TEMPERATURE

(DEG

C)

ELAPSED TIME (MIN)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 13 20

ELAPSED TIME (MIN) 0 1 Z 3 4 S 6 7 8 9 L0 11 12 13 14 IS 16 17 18 19 20

Figure 13. Temperature histories measured at 25 and 6 mm below the ceiling in the center of the full-scale and model bedrooms, respectively, for tests involving noncontributing interior finish materials.

36

TEMPERATURE

(DEG

C)

TEMPERATURE

(DEG

C)
(0 93Q) 3yniYH3d^l31

(o 93Q) 3aruYa3cn3i

£

CD

II

01 e> o —

37

Figure

14.

Summary

plot

illustrating

temperature

histories

measured

at

25

and

6

mm

below

the

ceiling

in

the

center

of

the

full-scale

and

model

bedrooms,

respectively,

for

selected

tests.
(0 030) 3HrUYH3dmi

D

(0 330) 3HfUYH3dW31

Q O o a a O a a o

O D Q a D o a o D

D ro ® © in m W

t3 ^

C O

<tf <4-1

38

Figure

15.

Temperature

histories

for

tests

with

lauan

plywood

walls

gypsum

board

ceilings.

A

propane

exposure

fire

was

used

test

M4B

50.

For

the

other

tests

methane

was

used.
SIDE = S = 3in

AREA = S

2 = 9in

ORIGINAL BURNER

SIDE = J2 S * 4'/4in

AREA = J4|/2 S)

2 = S2

EXPERIMENTAL BURNER

Figure 16. Plan view of the original square burner and the

experimental triangular burner used in the model.

39
ELAPSED

TIME

(MIN)

{3 03d) 3HaLVffldW3i qoqqdqoqoo D

Drooc^tom^nw

(3 030) 3tffUYM3dN31

40

Figure

17.

Temperature

histories

for

tests

with

lauan

plywood

walls

and

gypsum

board

ceilings.

The

triangular

burner

was

used

for

test

M4B

53.

For

the

other

tests

a

square

burner

was

used.
TEMPERATURE

(DEG

C)

TEMPERATURE

(DEG

C)

ELAPSED TIME (MIN)

ELAPSED TIME (MIN) 0 1 Z 3 4 5 6 7 B 9 LO 1 1 IZ 13 1 4 IS 16 17 IB 19 ZD

Figure 18 b. Lauan plywood walls and wood Fiber board ceilings.

Figure 18. Temperature histories illustrating the effect of the experimental

door opening for two combinations of interior finish materials.

41

CTURE

(DEG

C)

TEMPERATURE

(DEG

C)
LAPSED

TIME

(MIN)

m

Ll. 2

m

fear

c/i o

f±*il mS

Si

P~

"V —

Ear

M2

lx La. oo

Ixllxl 22

FF

(0 S30) 3MIUYH3dW31

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to in ^

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qQo

o _ O taj m

Q o

D o

m ®

o o a

o o a

to in ^

(0 330) 3HflLYH3cmi

42

Figure

19.

Temperature

histories

for

tests

with

lauan

plywood

walls

and

gypsum

board

ceilings.

For

test

M4B

58

the

experimental

door

opening

and

triangular

burner

were

used.

For

the

other

tests

the

original

door

opening

and

square

burner

were

used.
ELAPSED

TIME

(MIN)

(o £>3 a) 3anmi3dmi

(0 03Q) 3yfUVy3dH3i

43

Figure

20.

Temperature

histories

for

two

quarter-scale

tests.
1200 o o o o o O o o o

00 to OJ o CO tO cu o

X-l cn 00 h- ID ^r* CO OJ X-i

0)

4J H Ul C fl ffl CD £ P H "H -Q T5 >w £ O

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Eh P CO

(N

CL) P

3

CO •H

Cm

(33S) syoivoiaNi jo NoiiiNoi oi imi

44

RELATIVE

HUMIDITY

(%)
1200

LO

CO

in

lo

LO

in

co

LO

OJ

LO

o o o o o o o o o

CO CO OJ o CO co OJ o cn co h- CO CO OJ

xH

(03S) SyOlVOIQNI JO N0I1IN9I 01 3HI1

tn • w

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<u 3 -h

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S: 3

oi >i cn 3 -h O

tn aa

u x

<u c OJ > 3

3 >i

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4-) -H

4-1 Q) 3

E 'p

QJ

E3

UJa

>i H K t?

<NCM

<uu

3

tr> •H

&4

45

RELATIVE

HUMDITY

(%)
1080

LO

CO

LO

LO

LO

LO

CO

LO

OJ

LO

o O o o o o o o

CO OJ o CO CO OJ

CD CO h- co xt CO OJ vH

m

i—

-P rH • C QJ W (USD

•H &-L X! n -h £ o m

f0 o

£ 0J W >i P 3 H 3

in cl in

s-i o

oj c a

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o > -h

+j -H H-l 4->

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EH P 5

rn

(N

QJM

P

tn •H

fa

(03S) StiOlVOIdNI JO N0I1IN0I 01 3W11

46

RELATIVE

HUMIDITY

(%)
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4-> 03 -U rH o O

O

C

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V4

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a.*H 0 E 00 00 OPS E •^r • w x

rH <D CQ 0X

03

X

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C in in in

Q 4.X

X •rH • • • mum *H •H rH TU 3 (LI c crcn x

tow o

in 03

x

x

m to E 00 00 00

x o o

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a o 2

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cr>

X rH CM ro

•H rH 02X rH ID

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47
Table

cr> c

•rH .uw

oi E-C

T>

01Ww

pH

<U

•rHU

01

4-> (0 £1xm

•rHco

•rHu

0)

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01u

01>

01c

01

1-1

4J

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T>Co0

01 XX

V-l 01 T3C

=3

48

**

Material

is

labeled

as

meeting

Class C

requirement

(flame

spread

76-200)
Table

3.

Summary

Information

for

Tests

Using

an

Upholstered

Chair

or

Wood

Crib

as

the

Exposure

Fire

13w

C 1-. •r4 O CJ E 4J (IJ E TO to

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h-t

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4J LD

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in

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m

rH <D

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T3

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4-J

C

cu o 2 *rH 4J x cu in uc U <D O T3

•rH hH

0) CO

-U CO c 2

ix2m

CN

CN

r-ro

a:2

ro

CN

roo

CNO

00

CO

IS

C7»X <U In ^ H 4J -H

in cu vo m h x: h n o U Si i u

CD vo

rHI £ S

rHl CJ

<o VO

»—

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CN

CN

CN

-Q

D"» r—* »rH -X JD U

»H CJ '9"8£

vo I CJ

CD VO

rH

3:

ro

CN

00VOCN

X

-XX

U

rH CJ

r-H• O TO

cr» CNO

CD roI CJ

CD VO

rH5 a2O

CN

ino

ro

in

vo

ro

JO

C7»r^ *rH -X X U

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CO w

49

Notes 1)

All

tests

full

scale.

2)

Interior

finish

materials

used

on

walls

and

ceiling

for

all

tests:

marine

board

(in

corner)

over

gypsum

board

(throughout)
Table 4. Summary Information for Selected Tests

Using a Methane Burner as the Exposure Fire.

Test Number

Enclosure

Scale

F=Full

R=Reduced

Interior Finish Materials

NBS Identification Code

Relative

Humidity Temperature

Time to Flashover ** Walls Ceilincj % °C min : sec

Walls: Marine Board

Ceiling: Marine Board Burner Intensity: Low MFB 1 F W-16a C-13a NR***

M4B 1 R W-16 C-13 31* 21* NR

4 R W— 16 C-13 40* 22* NR

Walls: Marine Board

Ceiling: Marine Board Burner Intensity: Moderate

MFB 2 F W-16a C-13a NR M4B 5 R W-16 C-13 60* 22* NR

6 R W-16 C-13 46* 24* NR

Walls: Marine Board

Ceiling: Marine Board Burner Intensity: High MFB 3 F W-16a C-13a 66 19 NR M4B 9 R W-16 C-13 40* 22* NR

10 R W-16 C-13 33* 21* NR

Walls: Gypsum Board

Ceiling: Gypsum Board Burner Intensity: High MFB 9 F W- 19 C-9 40 18 NR

M4B 51 R W-19 C-9 24 24 NR

64 R W- 19 C-9 39 26 NR

Walls: Lauan Plywood

Ceiling: Gypsum Board Burner Intensity: Low MFB 8 F W-22 C-9 30 17 2:31 + M4B 15 R W-12 C-9 46* 24* 8:00

16 R W- 12 C-9 32* 23* 6:40

30 R W-22 C-9 47 24 16:20

32 R W-22 C-9 36 26 7:55

33 R W-22 C-9 42 26 10:35

50+ + R W-22 C-9 31 27 6:38

Walls: Lauan Plywood

Ceiling: Gypsum Board Burner Intensity: High MFB 6 F W-22 C-9 40 24 2:19

M4B 13 R W-12 C-9 35* 26* 4:30

14 R W-12 C-9 5:15

29 R W-22 C-9 47 24 7:30

31 R W-22 C-9 52 26 8:30

53 R W-22 C-9 35 26 4:15

54 R W-22 C-9 48 28 8:06

57 R W-22 C-9 46 28 5:59

58 R W-22 C-9 44 26 5:29

63 R W-22 C-9 54 27 7:37

50
Table 4. Summary Information for Selected Tests

Using a Methane Burner as the Exposure Fire (continued)

Test Number

Enclosure

Scale

F=Full

R=Reduced

Interior Finish Materials

NBS Identification Code

Relative

Humidity Temperature

Time to Flashover**

Walls Ceiling % °c min : sec

Walls: Lauan Plywood

Ceiling: Wood Fiberboard Burner Intensity Low MFB 7 F W-22 C-5 42 11 2:24 M4B 19 R W-12 C-5 34* 26* 4:55

21 R W-5 C-5 46 25 4:45

27 R W-5 C-5 40 24 4:53

61 R W-22 C-5 56 28 5:48

Walls: Lauan Plywood

Ceiling: Wood Fiberboard Burner Intensity: High MFB 5 F W-22 C-5 55 11 1:46 M4B 18 R W-12 C-5 54* 24* 3:30

20 R W-5 C-5 50 23 3:20

34 R W-22 C-5 61 24 4:15

35 R W-22 C-5 47 24 2:57

55 R W-22 C-5 32 27 4:16

56 R W-22 C-5 30 26 3:50

60 R W-22 C-5 31 27 3:33

INDEX TO METHANE BURNER EXPOSURE FIRES

Exposure

Fire Scale

Flow Heat Production

m 3 /hr ft 3 /hr kW Btu/min

Low Full

Quarter

8.02 284 0.50 18 84.1 4,783

5.2 296

Moderate Full

Quarter

10.70 378 0.69 24 112.1 6,378

7.0 399

High Full

Quarter

14.06 497 0.88 31 147.3 8,382

9.2 524

* Approximate

** Flashover as determined by ignition of newsprint indicator.

*** NR = Not Reached

t Newsprint ignition at 2:05 for test MFB 8 may have occurred early due to debris burning nearby. Flashover was judged to have occurred at 2:31 based

on heat flux on floor and upper air temperature,

ft For test M4B 50 propane gas was used.

51
Table

5.

Information

on

Peak

Temperatures,

Heat

Flux

Levels,

and

Flashover

Times

for

Tests

Using

a

High

Intensity

Exposure

Fire.

a

° £

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OOHNrlo\qoqqoqq'tOwqM»qcO'OcovOHOqNcO qq-}qcO'OOiOriqcM'ONiHiOqoocOcOOONrl<JOqNHOO' COCO\DiOcOvOiO'ON'OiOiOcOiA‘OiOiOiOiOiO'OvOiO(04tvDiO'OLO

Ob o CO 00 O Ob i—

m CO r^> rH CM CO <1* in M> 00 o CM CO MO 00 Ob o 4-1 cn

QJ

rH rH rH CM CM CO CO co •vf in m m m m m m m MO MO MO MO vO bO MO MO

PQ PQ PQ PQ PQ PQ PQ PQ PQ pq PQ PQ PQ pq PQ PQ PQ PQ PQ PQ PQ PQ PQ PQ PQ PQ PQ PQ PQ H <r <r St <T St St St sf St St St <T St <r St vt St St St St St St <r <r z z z z z Z z z z Z z z z Z z z z z z z z Z z z z z z z z

52

*NR

=

Not

Reached

**Only

first

indicator

ignited

and

may

have

been

influenced

by

debris

burning

on

floor

nearby.

***UD

=

Unreliable

Data
Table

6.

Information

on

Peak

Temperatures,

Heat

Flux

Levels,

and

Flashover

Times

for

Tests

Using a

Low

Intensity

Exposure

Fire.

c_> O rj o LO 3 U

4-1 o 0) sO o OS i—1 o -am co sO CN o

co i a CO pc: Pi CN CN rH CN o i—i o Cdi pi pi o m

m

0) • • 2 2 § 2 2 y p (3 CO CO CN i-H CN CN CO CN co CN CN co

•H

a •H

H cO

B

QJ vO D

nd CO

<u

M

C

O

•H 4-1

a 6 CO OJ •K o o m

m in CO o in

m 00 00

Mu CO •K Pi o m

m

m CNm co cy*k Pd Ptf CO CO

cu •H • • Pi 2 2 2 4-1 nd e 2 00 sO sO o sO

m sO

0)

d •H

r

—1 r-H

p

Q

M

B cn p-,

Ctf PP

04 •HH CM d G

04 o u > \ 0) sO r-H co sO CN o r-H rH CO CO O 2 CO P Pi m o m co Q i—1 rH Pi co CN

rC • • P 2 § § 2 w CN (3 sO o SO

m sO

CO •H i—1 r-H i—1 r—1 6

pq

U> CO CM

cOW

B

04

u 6 X P v— 3 3 2 N

m

m 00 00 6 i-H m s * CN r-H CO CN

•H 1 ^ T

H CN CJ P • • • • X P o o o o cO U ! -1 c & 2 cO CO

CD

D 43 c p H p o

OJ OJ o o o o o o o o o o o o o o o o o O B CO o o CO r-H co m o CN rH <3- r-H CN o o P •H • • H £3 o CO CO oo m m sO i£> CO r-H Os OS sO

sO

•H6rH CN 1 1 r-H rH rH rH rH

p 0)

cO )M

<u 3

Pm 4-1 o

cO

n «n rH os os CN CN CN r-H CO o SO o i—os sO CO

i-H

M oc

m r—oo SO os 00 OS 00 rH 00 CN in rH so i—1 0) 0) CN CN r^. VO sO sO sO sO SO sO CN CO CN sO so

cO

a P 6

a) 04 £ H

04! -1 £

rH 3 3 « P 4J O

a

•H cO cO P co o o rH 00 00 CN Is- o in OS r^. CN CO CN

4-» OJ ! -4

M CN o- os CN o CO *<r CO CO os CN CN co CO 00 o H ft 01 s 0) CN CN sO sO so sO sO sO CN CN <N m m m c 1 3. p P M 6

a> sO H ***

4-1 rH

m sO Os rH o CN CO sO < Os o rHm

W

(V H i—i rH rH rH CN CN co co CO CO

m sO so

PP pp pp pq PQ pq eq PP « pp pq PP pp pq pp pq pq NT <r <r •<r <* <r -<r <r <T *<r **3- <r •<r a a S S a a a a 2 a a a a a 2 a a

cfl 4-1 n) P

T3

<D Q) i—I 43

rO

U

nj to •H 0) Pi

0)

I-l 4-1 c o P 2

II II * **

53

***For

test

50

propane

was

used.

For

all

other

tests

methane

was

used.
Table

7.

Summary

of

Time

to

Reach

Flashover

in

Full-Scale

and

Time

to

Reach

500°C

or

375°C

in

Model,

w

4-1 Mooi-

raows3

44

t-i O

4-1

>1 Pwc

<D

x:CP •H

jc

44

<T5 W

>i

4-1 •HMC

0) 44c

•Ho wuo

4-4

<TJ 0Q U '3’ •H S T5 —C

•H r-H a> u fO

<u o > e oJ3 >4

0) o

f0 44 r4

44

UO

44

(0w

44m

<D 44

44Ocoo

44oe o0m

JSon3QJ

J4 1 o

44

CD£

Q) 'Vo£uO

44Uo

in

r»

ro

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(0

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14

44 44

<u I—

X3

05 Eh

<uowo£

14

<L» >O

szw

to i—

44

T3

a> 44wanT3<*K

54
Table

8.

Average

and

Peak

Temperatures

Measured

at

Different

Heights

in

the

Model

for

Selected

Tests. * 11 C * 1 o * 1 T} •-! o> 1 <11 4-> u | U *rH

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u o O

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U kH Li Li •rH TO

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CL) E CQ CQ CQ CQ CQ CQ CQ CQ CQ CQ CQ * * *

E- 3 N- * * Z s X x X X XXX X X * 1 *

55
Table

9.

Minimum

Oxygen

Concentrations

in

Bedroom

Doorway

at

Floor

Level 1111 111 111 111 1111 <D U) 1 1 1 1 1 > C X 1 1 1 1 1 o o cn 1 1 1 1 1 jC •rH QJ 1 1 1 1 1 U) 4-1 E* 1 1 1 1 t 03 03 1 1 1 1 1 rH P Jm 1 1 1 1 1

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C o i 1 i 1 1 CQ c x

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CP 03 i 1 i 1 1 C T7 03 03 | 1 1 1 -4 o c cn £ 1 i 1 i •rH to XI X

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58
NBS-114A (rev. 2-80

U.S. DEPT. OF COMM. O MM. BIBLIOGRAPHIC DATA

1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. Publ ication Date

SHEET (See instructions) NBSIR 81-2333 December 1981

4. TITLE AND SUBTITLE

Reduced-Scale Modeling of Mobile Home Fires: A Progress Report

5. AUTHOR(S)

David P. Klein

6. PERFORMING ORGANIZATION (If joint or other than NBS, see in struction s) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

Interim Report

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City. State, ZIP)

Division of Energy, Building Technology, and Standards

Office of Policy Development and Research

U. S. Department of Housing and Urban Development

Washington, DC 20410

10. SUPPLEMENTARY NOTES

2] Document describes a computer program; SF-185, FIPS Software Summary, is attached

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

bibliography or literature survey, mention it here) A series of fire tests was conducted in the bedroom of a single-wide mobile home

and in a quarter-scale model of that bedroom. The objectives of the tests were (1) to

evaluate the relationship between fire buildup in the reduced-scale and full-scale en- closures and (2) to determine the feasibility of using a reduced-scale model test to assess the potential contribution of particular combinations of interior finish materials to fire growth in a mobile home.

The model tests simulated the phenomena of fire growth and flashover; however,

the time to flashover occurred later in the model than in the full-scale bedroom.

Flashover was taken as the time at which the level of radiation at the center of the

floor reached 2 W/cm2

. Several modifications to the model were examined but none

adequately corrected the time delay to flashover. However, by monitoring the upper

air temperature in the model, the occurrence or nonoccurrence of flashover for cor- responding full-scale tests could be reliably predicted. Therefore, the use of a quarter-scale model was judged to be feasible.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Compartment fires; fire tests; flashover; interior finish; mobile homes; models; room fires

13. AVAILABILITY 14. NO. OF

PRINTED PAGES

[X] Unlimited

| ] For Official Distribution. Do Not Release to NTIS 64

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402. 15. Price

[5C] Order From National Technical Information Service (NTIS), Springfield, VA. 22161 $8.00

USCOMM’DC 6043-P80


I