Approved for public release by the

Director ot the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

NATIONAL BUREAU OF STANDARDS REPORT

6837

FIRE ENDURANCE AND HEAT TRANSFER

TESTS OF PREFABRICATED PANELS

by

Jr V . Ryan

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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NATBONAL BUREAU OF STANDARDS REPORT

NIBS PROJECT NESS REPORT

1002-40-10521 May 4, I960 6837

FIRE ENDURANCE AND HEAT TRANSFER

TESTS OF PREFABRICATED PANELS

by

J . V . Ryan

IMPORTANT NOTICE

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to reproduce additional copies for its own use.<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

FIRE ENDURANCE AND HEAT TRANSFER

TESTS OF PREFABRICATED PANELS

by

J. V. Ryan

ABSTRACT

Fire endurance tests were made on two wall

specimens and one roof specimen. Each was representative of prefabricated construction for use

in very cold climates. Three fire retardant paints

were used with the specimens, but did not influence

the results. The use of screws and washers as a means of prolonging the retention of gypsum board

on the fire exposed surface was found effective.

The fire endurances of the wall specimens were

significantly longer than that of the companion

roof specimen. Heat transfer tests were conducted

on two wall specimens.

1. INTRODUCTION

At the request of the U. S. Naval Civil Engineering

Laboratory, Port Hueneme , California, and Headquarters,

U. S. Air Force, tests were conducted on prefabricated

panels representative of wall and roof constructions.

These constructions were designed for use in polar regions.

Fire endurance tests were conducted on one roof specimen

and two wall specimens. Heat transfer tests were conducted

on two wall specimens.

2. SPECIMENS

The test specimens were assembled from prefabricated

panels. Each panel consisted of a wooden frame and a resin impregnated paper honeycomb insulation with a metal

skin cemented to each face. Gypsum board (identified by the

submittor as U. S. Gypsum Firecode 60), in 5/8-in. thickness

was cemented to the side to be exposed to fire-, corresponding

to the interior of a building. The individual panels locked

together to form the specimens. Details are shown in Figures

1 and 2. Specimens tested were:

2

1. Wall with perlite fill; fire test under load.

2. Wall without perlite fill; fire test under load.

3* Wall with perlite fill; heat transfer test.

4 . Wall without perlite fill; heat transfer test.

5. Roof with perlite fill; fire test under load.

Sufficient prefabricated panels, of the kinds and

sizes employed in buildings, were received from the manufacturer, Rohr Aircraft Corporation of Riverside, California,

to make up the required specimens.

2.1 Fire Test Specimens

The specimens for fire tests were made by assembling

the panels as received. No extra panels were available for

disassembly and detailed examination. Therefore, the descriptions are based in part on the representations of the designer,

some of which could not be checked during examination of the

debris after the tests.

2.1.1. Wall Specimens

Each wall specimen was approximately 10 ft high and

16 ft long; made by assembling four prefabricated panels.

Each panel (marked W-6) was 10 ft high, 4 ft wide, and 3

" 5/8 in.

thick, with a wooden tongue along the bottom and one vertical

edge and a groove along the other vertical edge and the top.

The metal surface to be away from the test fire was coated

with an unidentified paint. The gypsum board surface to be

exposed to the test fire was painted with one of three paints.

The latter painting was specified to have been one coat of

primer plus two coats of paint. One panel in each specimen

had an additional metal liner over the face of the gypsum

board. All three paints were applied to this metal liner,

each to about one third of the surface area. Data on the

coverages at which the paints were applied was not provided.

The paints were: Albi 107A, Glidden Duo-Tex, alkyd resin

(MH-P-17971B) . Each was used with the primer recommended

by the manufacturer.

- 3

-

The two wall specimens were identical in all but two

features. In the first wall tested, the honeycomb had

been filled with a perlite insulation; in the second, the

honeycomb was empty. As a result of the behavior observed

in the first test, it was decided to provide additional

support for the gypsum board on the second specimen. This

was done by means of 1-in. long No. 12, 13/32 in. cap head

self-tapping sheet metal screws, with 3/4 in. OD washers,

driven into holes drilled (No. 28 drill) through the gypsum

board and metal skin. The locations of the holes are shown

in Figure 1, at the end of this report. These screws were

put into only the two center panels of the specimen.

Details of the placement of the panels, joints, locking

system, etc., are shown in Figures 1 and 2.

2.1.2 Roof Specimen

The roof specimen was 16 ft long by about 12-1/2 ft

wide, made up of three roof panels, marked R2, plus an

angle panel, marked Rl, for transition from roof to side

wall. The roof panels were 16 ft long, 44 in. wide, and

5-

3/16 in. thick including 5/8 in. thick gypsum board. The

gypsum board was painted with one of three paints. The

painted surfaces were stenciled: Albi 107A, Glidden Duo Tex,

or MH-C-15328A . None of the roof panels had a metal liner

over the exposed surface of the gypsum board; all the roof

panels had perlite fill in the honeycomb. Additional

support was provided the gypsum board of one panel by 1 in.

long No. 12,13/32-in. cap head, self-tapping sheet metal

screws driven into holes drilled , through the gypsum board

and metal skin. The screws on one half the panel were used

without washers; those on the other half were used with 3 /^ in

OD washers. The screws were driven the day before the test

and were in addition to those around the peripheries of the

pieces of gypsum board (No. 8, 1-1/4 in. long flat head sheet

metal screws at 12 in. o.c.). The locations of the screws,

and other details, are shown in Figure 2.

2.2 Heat Transfer Specimens

Each heat transfer specimen was made from two wall panels

joined together, and then the excess cut from the periphery

to make a specimen 8 ft high and 5 ft 6 in. wide, with a joint

along the vertical centerline. One specimen had perlite fill;

the other did not. Examination after test indicated that the

paper honeycomb cells were 83 per cent full of perlite of

6-

5 lb/cu ft bulk density. The gypsum board faces of all

panels had been painted with Glidden Duo Tex.

- 4 -

2.3 Joint Treatments

The joints of all specimens were given the same treatments. Those on the unexposed or cold surfaces were covered

with an aluminum foil pressure sensitive tape 2 in. wide and

.0075 in. thick including adhesive (No. 428A of Minnesota

Mining & Manufacturing Co.). This tape was applied directly

to the painted metal surface of the assembled specimens.

The joints on the to-be-exposed or hot surfaces were filled

with cement and covered with paper tape in compliance with

recommended practice for gypsum wallboard. The joint cement

was applied to the painted wallboard and adhered to all but

that painted with Glidden Duo Tex. This paint was removed

mechanically after which the cement adhered satisfactorily.

After the cement had dried, each joint was given two coats

of Glidden Duo Tex.

3. TEST METHODS

The specimens were assembled, as shown in the figures,

in apparatus appropriate to the test to be performed. They

were instrumented and tested in accordance with the provisions

of recognized test methods. Although the specimens were

prefabricated, the details of mounting and sealing the joints

between the specimens and test equipment required some aging

before test.

3.1 Wall Specimens, Fire Tests

Each wall specimen for fire endurance test was mounted

in a movable steel and concrete frame equipped for the

application of load. The vertical joints between specimen

and mounting frame were stuffed with mineral fiber insulation

and plastered; the horizontal joints between specimen and frame

were covered with lath or fire brick and plastered. Thermocouples were placed on the unexposed surface, under felted

asbestos pads, in the locations shown in the figures.

Each frame, in turn, was clamped before the open face of

the wall furnace, and the specimen tested. During each test,

the specimen was subjected to an applied load of 500 lb per

linear foot. Temperatures were measured by thermocouples on

the unexposed surface and in the furnace chamber, the latter

encased in porcelain insulators and iron pipes. Lateral deflections were measured at midheight of each panel. The furnace fires were regulated to provide temperatures as close as

feasible to those defined for the standard time-temperature

curve given in ASTM E-119? which include: 1000°F at 5 min,

1300°F at 10 min, 1550°F at 30 min, and 1700°F at 1 hr.

- 5 -

3.2 Roof Specimen, Fire Test

The floor furnace was designed in such a manner that

specimens must he built or assembled in the frame that is

an integral part of the furnace.

The specimen was 16 ft long by about 12ft 8 in. wide

whereas the furnace frame was designed for specimens 18 ft

long by 13 ft 6 in. wide. This discrepancy made it necessary

to place supplementary steel in the furnace to support the

specimen. The supplementary steel provided bearing for the

long edge of one R2 unit, for both ends of all three R2

units and for the horizontal portion of both ends of the R1 unit

The fourth edge of the specimen, that edge of the R1 unit

that would bear on wall panels in actual use, bore on the

regular furnace bearing angles. This steel was protected

with metal lath and plaster which also sealed the joint

between steel and specimen.

During the test, the specimen was subjected to an

applied load of 50 lb per sq ft of roof area. Vertical deflections were measured at the center of the specimen.

Temperatures were measured on the unexposed surface, by

thermocouples under felted asbestos pads distributed as shown

in Figure 2; and in the furnace chamber, by thermocouples

encased in porcelain insulators and iron pipes. The furnace

fires were regulated according to the same time-temperature

curve as described for the wall tests.

3-3 Wall Specimens, Heat Transfer Tests

Each specimen, in turn, was placed in the National Bureau

of Standards' Rotatable' Guarded Hot Box apparatus, which

conforms substantially to the requirements of i\STM C236-5^T,

"Tentative Method of Test for Thermal Conductance and Transmittance of Built-Up Sections by Means of the Guarded Hot

Box." The peripheral edges were sealed and insulated to

minimize heat transfer or moisture migration through these

edges

.

The apparatus consists of a cold chamber and a hot or

guard chamber between which the specimen was secured. The

hot chamber contained a metering box 60 in. high and 32 in.

wide, centered on the face of the specimen. Temperatures

over this area were measured by means of 12 thermocouples

6

uniformly distributed over the panel plus three along the

joint. A matching array of thermocouples was used to measure

temperatures on the cold surface.

Each specimen was tested in a vertical position. By

means of the outer or guard chamber of the hot side, the air

surrounding the metering box was maintained at substantially

the same temperature as that within it. The electrical

energy supplied to the metering box was measured by means of

an integrating watt-hour meter. This measurement, converted

to heat energy, and divided by elapsed time, area of the

metering box face, and the temperature difference, yielded

the heat transfer coefficient of the specimen. The measured

energy input to the metering box was corrected for any slight

heat transfer due to temperature difference between the latter

and the guard box. Fans were used to promote uniform temperature distribution within the boxes. The energy supplied to

the fans was included in making the calculations.

The measurements of temperature and electrical energy

were made after the specimen and apparatus had reached

steady state temperature conditions. The temperature of the

air in the cold box was approximately 0°F and of that in the

metering and guard boxes was approximately 70°F.

4. RESULTS

The results of the fire tests are presented as summaries

of the logs of observations and plots of the time-temperature

and deflection data. The heat transfer tests did not produce

any observed mechanical changes in the specimens, hence the

results are given as computed values based on the data.

4.1 Fire Tests

The fire tests were designated 4ll, 412, 413 and were

conducted on three successive days.

4.1.1 Test 4ll, Wall with Perlite

The test was conducted on February 9? I960 and was witnessed by members of the staff of the Fire Protection Section,

National Bureau of Standards, plus the following:

- 7

-

J. R. Powers, Hq., USAF

c. W. Harris, Hq., USAF

T. Moller

,

Navy Dept .

,

BuYards and Docks

M. R. Herrmann, Navy Dept .

,

BuYards and Docks

D. E. Flohr, Navy Dept .

,

BuYards and Docks

B. General

,

Navy Dept .

,

BuYards and Docks

H. P. King, King,, Benioff & Associates, A

There was no observable lateral deflection as a result

of the application of load just before the start of the test.

There were intermittent flames on the exposed surface in

the first 6 min. The unexposed surface of the south-center

panel was wrinkled at 13 min. At 17 min, about 1/2 sq ft

of gypsum board fell from the south-center panel; the extra

metal liner on the exposed surface of the south panel was

warped and bulging. By 28 min, there were flames from the

exposed surface along all the joints plus several cracks

in the gypsum board. At 31-1/2 min, about 8 sq ft of gypsum

board fell from the north-center panel. By 35 min, this had

increased until about half the gypsum board was down from

the north-center panel plus about 8 sq ft from the south-center

panel with an equal area leaning on a furnace thermocouple pipe.

By 40 min, about 2/3 of the gypsum board had fallen from the

north-center and south-center panels and the exposed metal

was buckled. The condition of the unexposed surface at 4l min

is shown in Figure 3- At 51 min, smoke was coming through the

center joint and about half the gypsum board had fallen from

the north panel. At 58 min, the unexposed surface of the

south-center panel was discolored. At 1 hr, there appeared

to be an offset of about 1/2 in. along the joints on each

edge of the north-center panel. Flames came through the center

joint at 1 hr 3 min and the north joint at 1 hr 3-1/2 min; . see Figure 4. The test was stopped at 1 hr 5 min. The interior

of the specimen continued to burn. The frame and specimen

were removed from the furnace and the flames extinguished.

Temperature and deflection data are summarized in Figure 1.

Figure 5 shows the exposed surface at removal from the

furnace

.

The fire endurance of the specimen was limited by 325°F

rise above initial temperature at each of two thermocouples on

the unexposed surface at 1 hr 2 min. The correction for actual

furnace temperatures reduced this to 1 hr 1 min . The specimen

continued to support the applied load until it was removed

after the first breakthrough of flames at 1 hr 3 min.

- 8 -

Examination of the specimen after test showed that the

glue joint between the honeycomb and the exposed surface

metal skin was broken in all panels; but the joint between

the honeycomb and the unexposed surface metal skin was intact.

Most of the perlite was still in the honeycomb cells and the

paper of the honeycomb was charred to about 1-1/2 in. , or

half its depth, on the average. The wood framing members

were charred to about 2/3 of their depth.

4.1.2 Test 412, Wall without Perlite

The test was conducted on February 11, I960 and was

witnessed by members of the staff of the Fire Protection

Section, National Bureau of Standards, plus the following:

Jo R. Powers, Hq., USAF

Roy Legg, Hq., USAF

H. P. King, King, Benioff & Associates, A & E

There was no observable lateral deflection of three of

the panels as a result of the application of load just

before the start of the test. The fourth panel deflected

about .05 in. By 3 min, there were flames over the entire

exposed surface, but these were reduced to a few intermittent flames by 6 min. The extra metal linear on the

exposed surface of the south panel was warped by 11 min.

At 21-1/2 min, there were small flames from the exposed side

of the center joint and from a crack in the north panel.

By 28 min, there were flames from the exposed side of all

joints plus smoke from a seam in the unexposed surface of

the north-center panel. By 32 min, the flaming from the

joints was heavy. At 38 min, the south edge of the north

panel was open on the exposed side and heavy flames were

issuing from within the panel. The condition of the unexposed surface at 40 min is shown in Figure 6. At 4l min,

smoke was issuing from under the thermocouple pad on the

north joint. At 45 min, the unexposed surface of the north

panel was turning black. At 47-1/2 min, most of the gypsum

board on the north panel fell. At 50 min, about half the

unexposed surface of the north panel was blackened and the

paint on the upper half of the north-center panel hung in

a single large blister. The paint on the north panel burst

into heavy flaming about 51-1/2 min. At 54 min, about half

the gypsum board on the north center panel fell. The test

was stopped at 55 min. Figure 7 shows the unexposed surface

at 55 min, just after flames broke through the north joint.

- 9

-

The interior of the specimen continued to burn. The frame

and specimen were removed from the furnace and the flames

extinguished. Temperature and deflection data are summarized

in Figure 1.

The fire endurance of the specimen was limited by 325°F

rise above initial temperature at one thermocouple on the

unexposed surface of the north panel at 44 min. The correction for actual furnace temperatures increased this to 45 min . The specimen continued to support the applied load throughout

the test. The gypsum board on the north-center and south-center

panels, supported by the addition of sheet metal screws and

washers as described in 2.1.1, remained in place for all but

the last minute of test. About half of it remained in place

through the vibration incident to removal of the frame from the

furnace. See Figure 8.

Examination after test showed that the glue joint between

honeycomb and exposed surface metal skin was broken in all

panels; but the joint between honeycomb and unexposed surface

metal was intact. The honeycomb was charred full depth throughout and an appreciable amount washed away under the stream of

water (from a garden hose) used to quench the interior flames.

The wood framing of the panels had been completely charred

and most of it had been dislodged.

4.1.3 Test 413, Roof Specimen

The test was conducted on February 10, I960 and was witnessed by members of the staff of the Fire Protection Section,

National Bureau of Standards, plus the following:

J. R. Powers, Hq., USAF

H. P. King, King, Benioff & Associates, A & E

The center of the specimen deflected .04 in. under the

application of load just before the test. The exposed surface of the specimen was ablaze for the first few minutes

from the burning of the paper face of the gypsum board and

possibly the paints. This blazing had ceased by 5 min,

leaving charred paper on the surface. By 11 min, the gypsum

board on the west panel was noticeably out-of-plane. The

joint tape was loosened from the east joint at 22 min. By

24 min, flames were issuing into the furnace from all joints

and several cracks in the exposed surface. At 25 min, the

gypsum board fell from the south half of the center panel,

followed within a minute by that from the west panel. Smoke

issued from the unexposed surface through the west joint at

27 min and flames followed at 28 min, at which time the load

was removed. The sides of the center panel were open and
*
10

heavy flames from its interior issued into the furnace

chamber. The test was stopped at 32 min. The specimen

continued to burn and a stream of water was used to extinguish the flames. Temperature and deflection data are

summarized in Figure 2.

The fire endurance of the specimen was limited by 325°F

rise above initial temperature at one thermocouple over the

west joint, and by flaming through the west joint, both at

28 min. The applicable correction for furnace temperatures

increased this to 29 min . The specimen supported the load

until after the temperature rise and flame penetration

limits had been reached. However, the magnitude of deflection^ and the rate at which they were increasing made it

obvious that load failure would have occurred within the

next 1-1/2 minutes. Even with the load removed, the specimen

had sagged until it was resting on furnace thermocouple pipes

at the end of the test. Figures 9 and 10 show the unexposed

and exposed surfaces, respectively, a,fter test and removal

of the loading apparatus and instrumentation.

Examination after test showed that the glue joint

between the honeycomb and exposed surface metal skin was

broken in all panels; but that the joint between honeycomb

and unexposed surface metal skin was intact. The perlite

had fallen from the honeycomb cells. The honeycomb was

charred to its full depth along the edges of the individual

panels. The wood framing was charred to full depth where

the edges of the panels had opened during the test. The

gypsum board given additional support by cap head sheet

metal screws fell shortly after the end of the test, but

that given additional support by the same screws plus 3/I+ ino.d. washers remained in place.

4.2 Heat Transfer Tests

Based on the measured energy input to the metering box

and on the average temperatures maintained in the air and on

the surfaces of the specimens, the computed heat transfer

characteristics of the two specimens, including the effect of

the vertical joint between panels, were as follows:

11

Uninsulated Insulated

Observed thermal transmittance, u 0.20 0.14

Adjusted thermal transmittance, winter

,

Uw 0.212 0.145

Adjusted thermal transmittance, summer

,

Us 0.208 0.143

Thermal conductance, C 0.26 0.17

Warm surface conductance, fi 1.50 l . 58

Cold surface conductance, fo 2.14 2.17

The definitions of u, Uw , Us , C, fi and f 0 , representing

the various coefficients of heat transmission, are:

u - number of Btu/hr transmitted through each square ft

of panel for each degree F difference in temperature

between the air on the two sides, as observed under

the test conditions.

Uw

= u adjusted for a 15 mph wind outside and still air

on the inside by substituting for the observed surface conductances, design surface conductances fq =

1.4-6 and f 0 = 6.00, taken from the 1959 ASHRAE Guide.

Us = u adjusted for a 7-1/2 mph wind outside and still

air on the inside by substituting for the observed

surface conductances, design surface conductances

fi = 1.46 and f 0 = 4.00, taken from the 1959 ASHRAE

Guide

.

C = number Btu/hr transmitted through each square foot

of panel for each degree F difference in temperature

between the surfaces of the two sides, as observed

under the test conditions.

fi= number Btu/hr transmitted over each square foot of

panel area for each 1°F difference in temperature

between the inside air and the warm surface.

f 0= number Btu/hr over each square foot of panel area

for each 1°F difference in temperature between the

cold surface and the outside air.

Examination of each heat transfer specimen after t&st' revealed that the paper honeycomb extended to the edges and into

the corners of the core space, and was well bonded to both

metal facings.

12

5. DISCUSSION

The fire test of the wall with perlite fill indicated a fire endurance of 1 hr 1 min ; that of the wall without perlite

fill a fire endurance of 45 min ; and that of the roof, a fire

endurance of 29 min ; each for the particular specimen tested.

The variety of combinations of materials employed on

the exposed surfaces of the panels makes it difficult to

evaluate the effects of each. This is especially true since

no two adjoining panels were the same in all respects and the

behavior of each panel should have been influenced, to a certain extent, by the behaviors of those adjoining.

No significant temperature rise was observed on the unexposed surface of the roof specimen except at one thermocouple - that over the joint through which flames penetrated.

Therefore, there is practically no basis for comparisons among

the panels of this specimen.

5-1 Modes of Failure

The fire endurance of each wall specimen was limited by

325°F temperature rise on the unexposed surface of one or

more panels ; that of the roof by flame penetration through a joint. The only significant temperature rise on the latter

specimen was observed at a thermocouple on the joint through

which flames penetrated.

Flames penetrated both of the wall specimens but not

until after the temperature limits had been reached. In the

second wall test, the paint on the unexposed surface of one

panel burst into flames' several minutes before flames were

observed from the adjacent joint.

The structural behavior of the two walls were very similar.

Curves of the maximum net deflections against time are quite

close together. Each wall bowed toward the fire initially and

then away from it later. Each was still supporting the full

applied load at the end of its test. However, the lateral

deflections were increasing and it is doubtful that either

wall would have carried its load much longer.

- 13 -

The roof specimen was deflecting very rapidly at the

time flame penetrated one joint. It was obvious that

failure under load was imminent, or actually occurring. The

large and rapidly increasing deflections undoubtedly contributed to the opening of the joint at which failure occurred

by flame penetration.

5.2 Perlite Fill

That the presence of perlite fill in the honeycombs

was of significant benefit may be seen by comparing the

results between the two wall specimens, as well as the conditions of the two, after tests. The specimen with fill endured

the fire for a period of 16 min in excess of that without the

fill, despite the fact that the gypsum board was retained in

place more effectively on the latter. The paper honeycomb

and wood members of the filled panels were charred to an

appreciably lesser extent than those of the unfilled panels.

5.3 Gypsum Board

The fall of gypsum board from any panel was accompanied

by heavy flaming over the surface exposed. Therefore, it

seems logical to assume that the paperback-surface of the

gypsum board and the adhesive between it and the metal panel

face had been protected up to the time the gypsum fell, even

though the latter showed signs of calcination. Further indication of the insulating value of gypsum, even calcined, may

be obtained by comparing the unexposed surface temperatures

of the individual panels. In each wall test, an extra metal

liner over one panel retained the gypsum. In each test, the

surface temperatures of this panel were appreciably lower

than those of any other panel. Both the gypsum board and

the metal liner contributed to this fact. In the second wall

test, the unexposed surface temperatures of the two panels

with extra support for the gypsum were lower than those of

the other panel.

5-4 Joints

The mean unexposed surface temperatures measured over

the joints were surprisingly low in view of the fact that

joints frequently prove to be weak points in assemblies. In

the test of the wall with perlite fill, the joint temperatures

were lower than those of two panels from 45 min to 1 hr;

- lb -

in the test of the wall without fill, the joint temperatures

were lower than those of all the panels at the final temperature observations (50 min) and for all but about 15 min of

the test.

Flames penetrated joints in all the tests, but not until

after limiting temperature rise on panels in both wall tests.

Flame penetration occurred in the roof test before any significant temperature rise on the unexposed surfaces of the panels.

However, except at the joint through which the flames penetrated,

no significant temperature rise was observed over the joints

either

.

5.5 Paints

In the first wall test, the unexposed surface temperatures

on the panel with Albi 107A paint were lowest of the three

panels without metal liner; in the second wall test, they were

highest even before any gypsum board fell. Those on the panels

with Glidden Duo Tex and alkyd resin paints were fairly close

to one another in each test. Therefore, there appears to be

little, if any, basis for choosing among the paints so far as

fire performance is concerned. From the fact that the paper

surface of the gypsum board ignited immediately after the

start of the test, it is doubtful that any of the paints contributed to the fire endurances of the specimens.

5.6 Heat Transfer

Based on the minimum temperature difference across the

panels, which occurred at the joints, it is estimated that

the steady-state heat flow through the joints was about 10 to

15 per cent greater than the average heat flow through the

total panel area. Examination of the data indicated that for

outdoor air at 0 6 F and room air at 70°F, condensation might

be expected to form on the joint surface at relative humidities

above 58 per cent for the uninsulated panels and above 76 per

cent for the insulated panels.

- 15 -

6. SUMMARY AND CONCLUSIONS

The wall, with perlite fill or without, provided appreciably longer fire endurance than the roof. In the case of

a single-story building assembled from similar prefabricated

elements, failure of the roof would amount to failure of the

building so far as its contents were concerned. The longer

fire endurance of the walls would be of value if they separated adjoining buildings or spaces in the same building.

The results observed for the walls tested should not necessarily be expected to hold for walls having doors or windows.

The designs of the specimens and testing furnaces were

such that the joints between wall and floor, between wall

and roof, and between end and side walls were not tested.

There is no data from the tests to indicate how these joints

might affect the ability of the building assembly to withstand fire exposure.

The vertical joints between wall panels appeared to be

more resistant than the panels to transient heat flow under

the rapidly increasing "hot-side" temperatures of the fire

tests. This fact is probably due to the thermal capacity of

the comparatively high-density materials concentrated along

the joints. However, under the steady-state conditions of

the heat transfer tests, the joints leaked heat more rapidly

than did equal areas of the panels.

For interior air at about 70°F and outside still air at

about 0°F, the data indicated that moisture condensation on

the indoor surface of the walls should not be expected at

relative humidities up to about 76 per cent for the perlite

filled wall and about 58 per cent for the unfilled wall.

There appeared to be no basis for choosing among the

paints nor for assuming they contributed to the fire endurance

of the specimens.

UCOMM-NBS-DC

do‘ 3dniva3diM3i

Figure

1.

Construction

details

and

data

summary

for

wall

tests

r

J8in

Is?

isi

ir

F<

l

0) 2

tuO •H

Jo‘3dniVd3dW3l

Figure 3* Unexposed surface of perlite-filled wall at 4l min.

lexposed surface of perlite iilJed wall as names

’oke through north joint, 1 hr 3t min. Figure h.

p

in0

-P0

0PP

0

i—I * P >> 0 r—

I

> 0

o

T30 H

i—I 0

i—I 0

•H 0 P P

1 0 P

P ,0 •H bO P P

0 0

0P 0

O

P

O 0

0

0 0

O P

0 (—

I

P

0 r—

I

0 0P

0 0 0

0

in 0

O 0 PP

W X W 0

IP

0

0

0

bO

•H

IP

Figure 6. Unexposed surface of wall without perlite fill at 4-0 min.

:?v

;h Fv'f

'

Figure 7 Unexposed surface of wall without perlite fill at 55 win

’ 'i» ' , ' >'

Figure

8.

Exposed

surface

of

wall

without

perlite

fill

immediately

after

testExtra

screws

and

washers

in

two

center

panels

only*,

extra

metal

liner

on

right

panel

only-

Figure

9-

Unexposed

surface

of

roof

specimen

after

test

and

removal

of

loading

equipment.

Figure

10.

Exposed

surface

of

roof

specimen

after

test.

Extra

screws

-in

near

end

of

right

panel;

screws

and

washers

in

far

end

of

same

panel.

U,S. DEPARTMENT OF COMMERCE

Frederick H. Mueller, Secretary NATIONAL BUREAU OF STANDARDS

A. V, Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its major laboratories in Washington, D.C., and

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Its title, A brief description of the activities, and of the resultant publications, appears on the inside of the front cover, WASHINGTON, D.C.

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Building Technology, Structural Engineering, Fire Protection. Air Conditioning, Heating, and Refrigeration. Floor, Roof, and Wall Coverings. Codes and Safety Standards. Heat Transfer. Concreting Materials.

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Digital Systems. Analog Systems. Application Engineering.

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Services. Sun-Earth Relationships, VHF Research. Radio Warning Services. Airglow and Aurora. , Radio

Astronomy and Arctic Propagation.

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