NIST IR 7471 

Analysis of Inter-laboratory Testing of 

Non-loadbearing Gypsum/Steel-Stud 

Wall Assemblies 

William Grosshandler 

Samuel L. Manzello 

Alexander Maranghides 

Tensei Mizukami 

NISTIR 7471

 

William Grosshandler

Samuel L. Manzello

Alexander Maranghides

Building and Fire Research Laboratory

Tensei Mizukami

Center for Better Living

December 2007

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

National Institute of Standards and Technology

Jim Turner, Acting Director

Analysis of Inter-laboratory Testing of 

Non-loadbearing Gypsum/Steel-Stud 

Wall Assemblies

 
ii 
ABSTRACT 

This report summarizes the results of a test program conducted in 2006 and 2007 by the North 

American Fire Testing Laboratories (NAFTL) consortium. Gypsum/steel-stud wall assemblies, 

nominally rated at 1-h, were tested by six different organizations in North America employing 

ten different furnace facilities following the guidance provided in ASTM E119-00. The 

participating NAFTL laboratories arrived at an identical 1-h rating for the gypsum wall specimen 

tested according to their respective standard operating protocols. The average time to failure 

(defined by the temperatures reached on the unexposed side of the specimen) was 65 ± 2.8 

minutes. The variability in individual peak thermocouple temperatures measured at similar 

locations on the different wall assemblies exceeded ± 50 oF around one hour into the test, and 

reached a maximum of close to ± 150 oF at the average time of failure. Differences in the time to 

failure for the ten close-to-identical wall assembly tests did not correlate at a statistically 

significant level with differences in average furnace temperature, the temperature-time integral, 

changes in ambient temperatures, or standard deviation among the furnace control thermocouple 

temperatures. Six inter-laboratory tests were also conducted by several Japanese organizations, 

yielding an average time to failure of 67.1 ± 1.1 minutes. The inter-laboratory program 

described in this report is the largest ever conducted for fire resistance testing and forms the basis 

for future programs aimed at testing additional structural materials, elements, and systems 

subjected to fire test standards referenced in building codes. 

iii 
ACKNOWLEDGEMENTS

 

The authors acknowledge the essential contributions made by each of the North American 

laboratories who conducted the fire resistance tests for the wall assembly: Intertek, Underwriters 

Laboratories (UL), Southwest Research Institute (SwRI), NGC Testing Services, Western Fire 

Center, National Research Council of Canada (NRC-C), and U.S. Gypsum (USG). The authors 

would also like to acknowledge the participating Japanese laboratories: Center for Better Living, 

Japan Testing Center For Construction Materials, General Building Research Corporation of 

Japan, Japan Housing and Wood Technology Center, and Foundation Test Laboratory. U.S. 

Gypsum supplied 100 % of the gypsum board, created in a special factory run to ensure tight 

quality control. Western Fire Center is acknowledged for handling and shipping the gypsum 

board to the different laboratories, including to the participants in Japan. The assistance of the 

American Council of Independent Laboratories (ACIL) was essential to maintain the anonymity 

of the test results. Mr. Dale Bentz of NIST assisted with the thermal property measurements. 

DISCLAIMER 

Certain companies and commercial products are identified in this paper in order to specify 

adequately the source of information or of equipment used. Such identification does not imply 

endorsement or recommendation by the National Institute of Standards and Technology, nor 

does it imply that this source or equipment is the best available for the purpose. 

POLICY OF NIST REGARDING THE INTERNATIONAL SYSTEM OF UNITS 

The policy of NIST is to use the International System of Units (metric units) in all publications. 

In this document, however, units are presented in metric units or the inch-pound system, 

whichever is prevalent to the discipline. 

iv 
TABLE OF CONTENTS 

page

ABSTRACT iii 

ACKNOWLEDGEMENTS iv 

DISCLAIMER iv 

POLICY OF NIST REGARDING THE INTERNATIONAL SYSTEM OF UNITS iv 

LIST OF ACRONYMS vi 

BACKGROUND 1 

NAFTL TEST PROGRAM 2 

TEST PROCEDURES 3 

TEST RESULTS 10 

ANALYSIS OF RESULTS 17 

REFERENCES 22 

APPENDICIES 

 A. Plots of unexposed face thermocouples for laboratories A-1 through A-10 23 

 B. Results from Japanese inter-laboratory test program 28 

v 
LIST OF ACRONYMS 

ACIL American Council of Independent Laboratories 

ATF Bureau of Alcohol, Tobacco, Firearms and Explosives 

ASTM American Society for Testing and Materials 

DSC Differential Scanning Calorimeter 

FM Factory Mutual 

ISO International Organization for Standardization 

NAFTL North American Fire Testing Laboratories Organization 

NFPA National Fire Protection Association 

NIST National Institute of Standards and Technology 

NRC-C National Research Council - Canada 

SwRI Southwest Research Institute 

TC Thermocouple 

UL Underwriters Laboratories 

vi 
Analysis of Inter-laboratory Testing of Non-loadbearing Gypsum/Steel-Stud 

Wall Assemblies 

BACKGROUND 

In the aftermath of the World Trade Center collapse, a possible building code requirement that 

highrise structures withstand a complete burnout is being discussed in the U.S. 

Compartmentation and the integrity of bearing and non-bearing walls play a role in the severity 

and rate of spread of the fire, and thus the fate of the structure in a burnout scenario. 

The ability of a structural element or system to withstand a fire is rated by subjecting the 

element, or a representative section of the system, to the heat of a furnace. Wall systems 

approximately 10 ft by 10 ft in area are evaluated by mounting them in a fixture and exposing 

them to a flame in a furnace with a prescribed temperature rise. ASTM E 119-00: Standard Test 

Methods for Fire Tests of Building Construction Materials is often cited in the U.S. model 

building codes; NFPA 251 and UL 263 are equivalent test methods. ISO 834-1 is the similar 

international standard, although it is never used in U.S. construction. Details on these and other 

test methods used to characterize the fire resistance of walls and other building elements are 

reviewed elsewhere (e.g., Grosshandler, 2002; Grosshandler, 2006). While there are some 

differences among the test protocols, the general procedures and many of the measurements 

prescribed in all four test methods are similar. 

The fire resistance of the wall assembly in an actual building fire is assumed to be related to the 

length of time necessary for the test specimen to meet any one of several failure criteria: 

• The maximum temperature increase on the unexposed side of the wall exceeds 325 oF; 

• The average temperature increase on the unexposed side of the wall exceeds 250 oF; 

• A breach occurs in the wall that allows hot gases from the furnace to penetrate and ignite a 

cotton target on the unexposed side of the wall; or 

• The wall is unable to maintain its design load. 

The fire resistance rating of the wall system is defined as the time (to the next lowest half-hour 

increment for times up to two hours, and to the next lowest hour for longer times) when any of 

the criteria indicated are exceeded. It is expected that a 2-h rated wall would resist failure in a 

real fire for a longer period of time than a similarly functioning 1-h rated wall, and this is 

invariably the case. What can not be expected, however, is that a 2-h rated wall would 

necessarily withstand an actual fire in a building for two hours, or that the wall would necessarily 

fail after two hours. The inability of the fire resistance rating to act as an absolute predictor of 

performance in an actual fire was recognized from the beginning when the forerunner of ASTM 

E119 was published in 1918. Over the years, however, the reference to fire resistance ratings in 

common time units has become erroneously interpreted to relate closely (or at least 

conservatively) to the actual time that a wall would be expected to resist a fire. 

The shortcomings of the current methods for rating the fire resistance of wall systems are 

numerous; some are obvious and have been recognized for years: 

1
• The maximum size of the wall system is limited by the size of the furnace. 

• The load conditions for the test article may not adequately mimic field use. 

• The thermal environment of the furnace does not mimic a real fire. 

• The tests reveal no fundamental information about the performance of the specimen and 

provide little guidance on how to improve performance. 

• The furnaces themselves are not standardized; hence, the same specimen could receive 

different ratings if tested in two different facilities. 

• Ratings are based upon a single test, with no way to quantify the uncertainty or safety factor. 

In spite of severe shortcomings, these test methods continue to be used throughout the world 

because (i) a massive data base has been established and is in continual use, (ii) history suggests 

that the test methods are conservative, and (iii) alternative methods have not been developed yet 

that are acceptable to the major parties involved. 

NAFTL TEST PROGRAM 

Designing structures to withstand the hazard posed by an unconfined building fire requires that 

standard fire resistance tests be reliable and consistent, independent of the laboratory performing 

the test. Ascertaining the consistency of testing in North America is the focus of this report. 

North American Fire Testing Laboratories Consortium1

The North American Fire Testing Laboratories (NAFTL) consortium was formed in 2004 to 

provide a forum for the exchange of technical information, to conduct studies, and to develop 

industry consensus positions relating to the full range of fire tests; e.g., reaction to fire, fire 

suppression, fire resistance and fire detection. The organization is open to any North Americanbased independent commercial laboratory engaged in fire testing or research. Current members 

include Southwest Research Institute (SwRI), Underwriters Laboratories (UL); FM Approvals, 

Intertek, NGC Testing Services, and Western Fire Center. The National Institute of Standards 

and Technology (NIST), the National Research Council of Canada (NRC-C), and the Fire 

Testing Laboratory of the Bureau of Alcohol, Tobacco, and Firearms (ATF) are non-voting 

associate members of NAFTL. 

The operations of the member laboratories of NAFTL are certified according to ISO 17025, 

General Requirements for the Competence of Testing and Calibration Laboratories. As part of 

the certification process, organizations must demonstrate to a certifying body that they are 

proficient in conducting fire testing services offered to their customers, a task which is difficult 

for a test like ASTM E119. For this reason, and to gain a better understanding of the test itself 

as a means to overcome the shortcomings previously enumerated, NAFTL organized a test 

program for ASTM E119-00 using a common structural element: a gypsum/steel-stud wall 

assembly. 

 

1

 http://www.naftl.org/ 

2
Participants and Objectives 

A total of ten different laboratories representing seven different organizations participated in the 

test program. They included Intertek, UL, SwRI, NGC Testing Services, Western Fire Center, 

NRC-C, and U.S. Gypsum. All of these laboratories routinely operate large-scale furnaces that 

rate the fire resistance of structural elements such as building partitions and non-load-bearing 

walls. In addition, several Japanese organizations conducted their own inter-laboratory testing 

using the identical materials and wall design as used by NAFTL. The results of the Japanese 

program are presented in the appendix. 

The guidance provided in ASTM E119-00 is imprecise with regard to the details on the design of 

the testing furnace, and the guidance allows some leeway in how the sample is to be prepared 

and instrumented, as well as the way the test is to be conducted. Thus, it is not surprising that 

different laboratories develop different standard operation procedures that are still within the 

constraints of the prescribed test method. In addition, the dimensions and materials used in 

constructing the test article often differ, and may not be within the control of the fire testing 

laboratory. When differences in ratings occur of ostensibly the same test article, it is not possible 

to discern whether the cause of the difference is the test article itself, the differences in furnace 

design and instrumentation, or the differences in operational procedures. In order to assess these 

differences and how they might lead to uncertainty in the fire resistance rating of a product, 

proficiency testing is necessary using a standardized product, with the results of the testing 

accumulated and analyzed by a qualified independent party. 

The objective of the current testing program is to compare the behavior of different vertical 

furnaces and identify operational parameters that influence the performance of a generic nonload-bearing wall assembly undergoing an ASTM E119-00 resistance to fire test. The testing 

was conducted in accordance with the standard operating protocol of each participant. 

The data from each test were collected in a common format and sent to the American Council of 

Independent Laboratories (ACIL), who acts as the secretariat for NAFTL. ACIL removed all 

identifying information from the data and delivered it to NIST, who was the qualified 

independent party responsible for analyzing and reporting the data. 

The outcome from this test program is being used by the participating organizations to assess the 

relative performance of their furnaces. The data collected are also being used by NIST to help 

develop the needed relationship between furnace behavior and actual fires. 

TEST PROCEDURES 

Wall Assembly Description

The wall assembly was designed to be non-load bearing, nominally 1-h fire resistance rated, and 

consisting of a 5/8 inch thick type X gypsum board (ASTM C1396), 10 ft by 10 ft with taped, 

staggered vertical seams, on each side of steel studs located on 16 inch centers. The geometry 

of the wall specimen is shown in Fig. 1. The gypsum board was obtained by the individual 

3
laboratories in a single lot from the manufacturer since it was desired to have as little variation as 

possible in the test specimen. All laboratories used steel studs (25 gauge) and fasteners (1 1⁄4 in 

long Type S drywall screws) obtained from a single supplier. 

The wall assembly was instrumented according to the provisions in ASTM E119-00. Additional 

thermocouples (type K) were located as indicated in Fig. 1 to measure the temperature within the 

wall cavity. The walls were constructed using each laboratories' established practice. Figure 2 

shows a wall specimen being assembled. 

Figure 1. Gypsum/steel-stud wall assembly and location of thermocouples 

4
Figure 2. Wall specimen being constructed 

Properties of Gypsum Board

The properties of gypsum board can vary, even if extra care is taken by the manufacturer and the 

board is all cut from a single run. Because the performance of the wall assembly depends upon 

the thermal and physical properties of the gypsum board, the total weight and density of each 

specimen was recorded by the individual testing laboratory. Based upon the results obtained 

from each test laboratory, the room temperature density of the gypsum board was 47.40 lb/ft3

 ± 

0.37 lb/ft3

 (mean ± standard deviation). For comparison, the density of the gypsum board 

samples used in the NAFTL series were also determined at NIST based upon measurements of 

the dimension and mass of individual 6 inch by 6 inch gypsum board samples. The measured 

density was 47.45 lb/ft3

 ± 0.47 lb/ft3. The results obtained by NIST are in good agreement with 

those obtained by the test laboratories. 

In addition to determining the room temperature density, measurements were performed using 

the Hot Disk Thermal Constants Analyzer® (TPS 2500) to determine the room temperature 

thermal conductivity and specific heat of representative samples of gypsum board. The Hot Disk 

determines thermal properties using the transient plane source technique (TPS). As the Hot Disk 

5
provides the volumetric heat capacity, the room temperature density was used to determine the 

specific heat on a mass basis. The sizes of the gypsum board samples used were 6 inches by 6 

inches. These measurements were performed with the paper in place and with the paper 

removed from the gypsum board samples. For the paper in place, experiments were conducted 

with the brown paper side in contact with the probe as well as the grey paper side in contact with 

the probe. The results are summarized in Table 1; the uncertainty in these results is ± 10 %. The 

uncertainty is dependent upon material variability as well as the uncertainty of the analyzer used. 

As can be seen, the effect of removing the paper does not have a significant effect on the 

measured thermal conductivity at room temperature. For the specific heat, it appears that the 

specific heat of the paper backing is higher than the gypsum material. 

Table 1. Thermal conductivity and specific heat at 70 oF taken with hot disk (virgin material) 

Thermal 

Conductivity 

(Btu/h-ft°F) 

Grey Paper 

Thermal 

Conductivity 

(Btu/h-ft°F) 

Brown Paper 

Thermal 

Conductivity 

(Btu/h-ft°F) 

No Paper 

Specific Heat 

(Btu/lb°F) 

Grey Paper 

Specific Heat 

(Btu/lb°F) 

Brown Paper 

Specific 

Heat 

(Btu/lb°F) 

No Paper 

0.16 0.16 0.16 0.26 0.24 0.21 

The thermal conductivity and specific heat were also determined as a function of temperature for 

representative gypsum board samples. The thermal conductivity as a function of temperature 

was determined using the Slug Calorimeter (Bentz et al., 2006). The slug calorimeter is 

comprised of a square central stainless steel plate (6 inches by 6 inches by 1⁄2 inch). A set of 6 

inch by 6 inch gypsum board samples (with paper carefully removed) was installed in a 

‘sandwich’ configuration (i.e. steel slug in the center); this provided an adiabatic boundary 

condition at the central axis of the slug plate. This entire configuration was then placed at the 

bottom of an electrically heated box furnace and the temperatures of the metal slug and exterior 

gypsum board surfaces were recorded during multiple heating and cooling cycles. The effective 

thermal conductivity was estimated knowing the heat capacities and densities of the steel slug 

and gypsum board samples (determined for the gypsum board using the Hot Disk measurements 

above). 

During the first heating cycle, the gypsum dehydrated, absorbed some of the energy, and delayed 

the temperature rise of the slug. As a result, the thermal conductivity was determined based 

upon the second heating/(natural) cooling cycle and is displayed in Fig. 3. The thermal 

conductivity exhibits a slight decrease with temperature then steadily increases with temperature; 

similar behavior has been observed in thermal conductivity measurements for other gypsum 

board types (Bénichou and Sultan, 2005). 

To determine the specific heat as a function of temperature, Differential Scanning Calorimetry 

(DSC) was used. DSC specific heat measurements were taken following the procedure outlined 

in ASTM E 1269-2001 at a scanning rate of 36 °F/min. The gypsum board samples used were 

0.02 lb in initial mass. To accommodate the gas generation incurred from dehydration, the 

sample, reference and standard measurements utilized pans that were sealed except for a 0.002 

inch pinhole in the lid. 

6
0

0.05

0.1

0.15

0.2

0 200 400 600 800 1000 1200 1400

Apparent k ( Btu/hftoF )

Temperature ( oF )

Figure 3. Thermal conductivity of gypsum board (previously heated) as a function of temperature 

determined with slug calorimeter 

The core material of gypsum board is a porous solid composed primarily of calcium sulfate 

dihydrate (CaSO42H2O), a naturally occurring mineral in which two water molecules are 

chemically bound for every one calcium sulfate molecule within the crystal matrix. The 

presence of the water molecules is a key feature in establishing the fire resistance properties of 

gypsum. When heated, crystalline gypsum dehydrates and water is liberated, typically in two 

separate, reversible chemical reactions (Ramachandran et al., 2003): 

 CaSO42H2O+Q ↔ CaSO4(1/2)H2O+(3/2)H2O (1) 

CaSO4(1/2)H2O+Q ↔ CaSO4+(1/2)H2O (2) 

Both of these dehydration reactions are endothermic and generally occur at temperatures 

between 257 °F and 437 °F. 

7
0

1

2

3

4

5

0 200 400 600 800 1000 1200

Cp ( Btu/lboF )

Temperature ( oF )

 

Figure 4. Specific heat of gypsum board as a function of temperature 

At a temperature around 752 °F, a third, exothermic reaction occurs, in which the molecular 

structure of the soluble crystal reorganizes itself into a lower insoluble energy state (hexagonal to 

orthorhombic): 

CaSO (sol) CaSO (insol) 4 4 → + Q (3) 

These reactions can be observed in the Differential Scanning Calorimetry (DSC) traces presented 

in figure 4. The first two reactions are strongly endothermic while the third reaction is slightly 

exothermic. The DSC traces show that significant reaction, and thus water loss, is completed by 

the time the board reaches 400 °F. Similar findings for specific heat as a function of temperature 

have been reported for other gypsum board types (Bénichou and Sultan, 2005; Manzello et al., 

2007). 

Conduct of Test

The instrumented specimen was mounted on the vertical wall furnace and prepared for testing 

using the standard procedure of the respective laboratory. The furnace was controlled to follow 

the standard time-temperature curve specified in ASTM E119-00. Temperatures of the specimen 

8
and furnace were collected at least once a minute. A video record of the entire test was made, 

along with photos of observed damage to the specimen when it occurred. A thermal imaging 

camera was used in several of the tests to view the unexposed side of the wall assembly. Figure 

5 is a thermal image of a wall specimen during one of tests. The actual instrumentation 

employed and its placement on the specimen was recorded by each laboratory. The tests were 

documented and, in several cases, witnessed by NIST research staff. 

The test was designed to continue until all of the following conditions were met: 

• The average temperature of thermocouples used in standard practice by the laboratory on the 

unexposed side of the specimen reached 250 o

F above its initial average temperature; 

• At least one thermocouple used in standard practice by the laboratory on the unexposed side 

of the specimen reached a temperature 325 o

F above its initial temperature; and 

• A crack opens up in the specimen large enough and hot enough to ignite cotton waste. 

The hose stream test (which is specified in ASTM E119-00) was not applied to the specimen. 

Figure 5. Thermal image of unexposed side of wall assembly during test

9
Each laboratory prepared a standard ASTM E119-00 data sheet for the tests conducted. In 

addition, data were compiled for the temperature vs. time for all specimen thermocouples and 

temperature vs. time for the furnace control thermocouples. 

These data sheets were collected by ACIL and sent to NIST for analysis, without identifying 

which data set belonged to which laboratory. The assessment is based upon how much an 

individual laboratory differed from the following composite results of the group: 

• Time for the average temperature to reach 250 oF above its initial average 

• Time for the first thermocouple to reach 325 oF above its initial temperature 

• Time for a crack to open up sufficient to ignite a cotton swab 

• T vs. t for the peak temperature 

• T vs. t for the average temperature 

TEST RESULTS 

Average Furnace Temperatures

The temperature of the furnace is determined from the average of multiple shielded, slow timeresponse thermocouples located within the furnace cavity. Most furnaces are controlled 

manually, with an experienced operator increasing or decreasing the fuel flow to different 

burners to maintain uniformity at the temperature specified in ASTM E119-00. At five minutes, 

the furnace temperature is required to be 1000 oF; at fifteen minutes it must be 1399 oF; the target 

temperature at one hour is 1700 oF; and at two hours the temperature is 1850 oF. 

The temperatures of the laboratory furnace tests, designated A1 through A10, are plotted in Fig. 

6. The dotted red line represents the average of the ten tests and the vertical red bars represent 

one standard deviation around the mean of the ten tests. During the start-up period, several of 

the furnaces tend to either lag or over-correct, but by fifteen minutes into the test, eight of the ten 

furnaces fall close to a single curve. Furnace A3 lags the group until about 40 minutes into the 

test. 

Figure 7 demonstrates how closely the furnace temperatures follow the standard temperature 

curve. The times specified to reach a given temperature in the standard test are shown on the top 

axis of Fig. 7. One can see that during the first five minutes of warm-up, the test furnaces 

deviate by as much as 400 o

F from the E119 temperature, and are most often on the low side. At 

temperatures above 1400 o

F, all ten furnace temperatures are clustered close to the specified 

E119 temperature. The Standard requires that the integral of the temperature over time be within 

7.5 % of the specified curve for tests lasting more than one hour. The areas under the 

temperature curves, listed in Table 2, were all within 2 % of the area specified in ASTM E119-

00 (82 330 o

F-min). Also shown in Table 2 are the initial ambient laboratory temperatures, 

which ranged between 62 o

F and 92 oF. The Standard assumes, but does not require, that the 

initial laboratory temperature is 68 oF 

 

10
Average Furnace Temperatures

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 20 40 60 80 100 120

Time, minutes

Temperature, o

F

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10

AVE

Figure 6. Average temperature of each of ten furnaces as a function of time 

Furnace Temperatures

0

200

400

600

800

1000

1200

1400

1600

1800

0 200 400 600 800 1000 1200 1400 1600 1800

ASTM E119 Temperature, o

F

Test Furnace Temperatures, o

F

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10

1 2 3 4 5 6 8 10 15 Time, minutes

Figure 7. Individual furnace temperatures vs. prescribed ASTM E119 temperature 

11
Average Furnace Pressures

-0.250

-0.200

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0 10 20 30 40 50 60 70

Time, minutes

Pressure, in. of water

A2

A3

A4

A5

A6

A8

A9

A10

Figure 8. Furnace pressure as a function of time 

Average ASTM TC 

Temperature Increase

0

100

200

300

400

500

600

700

0 10 20 30 40 50 60 70

Time, minutes

Tave-Tambient, o

F

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10

E119 limit

Figure 9. Average ASTM TC increase on unexposed face

12
Table 2. Ambie laboratory tests 

Laboratory 

Ambient 

Temperature, o

F

T-t Integral, o

F-min

Deviation from 

ASTM E119 

nt temperature and temperature-time integrals for the interA1 68 82 880 0.7 % 

A2 92 82 980 0.7 % 

A3 62 80 650 2.0 % 

A4 66 80 860 1.8 % 

A5 70 81 480 1.0 % 

A6 82 81 790 0.6 % 

A7 90 81 880 0.5 % 

A8 70 81 960 0.4 % 

A9 78 82 550 0.3 % 

A10 76 82 430 0.1 % 

Furnace Pressure

s 

The furnace pressure was recorded continuously for eight of the ten tests, and these are plotted in 

Fig. 8. The pressures (relative to the surrounding laboratory) remained fairly constant and 

around zero after an initial transient that lasted less than five minutes. The measured relative 

pressures ranged from about -0.07 in. H2O for test A2 (where the pressure probe was located 24 

in. above the bottom of the wall) to +0.05 in. H2O in test A4 (location of the pressure probe wa

unspecified). Proper interpretation of these pressure data requires knowing the location of the 

probe in the furnace. 

Average Temperature of Unexposed Wall

Appendix A contains the temperature-time plots for all of the individual thermocouples on the 

unexposed wall for tests A-1 through A-10. The average temperature increase on the unexposed 

wall for each laboratory test is shown in Fig. 9. Note that the ambient temperature (which varied 

between 62 o

F and 92 oF as listed in Table 2) has been subtracted from the average temperatures. 

entioned earlier, one of the criteria for rating the fire resistance of a wall assembly is th

e when the average temperature of the thermocouples on the unexposed side of the specim

reaches 250 o

F above its initial average temperature. This limit is shown as the dotted red line in 

Fig. 9. The temperature profiles are closely grouped for the first 56 minutes and then begin to 

diverge. None of the average temperature increases exceed the threshold before 60 minutes, and 

all have exceeded the threshold by 70 minutes. 

 

As m e 

tim en 

Figure 10 is a plot of the standard deviation of the curves graphed in Fig. 9. The standard 

deviation remains less than 20 o

F until the time approaches the 60 minute mark, when the 

13
250

Figure 10. Standard deviation among 9 ASTM TCs on unexposed side of each specimen tested 

Figure 11. Individual test unexposed surface average temperature vs. mean of all ten tests 

ASTM TCs

0

25

50

75

100

125

150

175

200

225

0 0 2 30 4 50 60 70

Time, minutes

Standard Deviation, o

F

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10

1 0 0

~55 ~ 65 Time, minutes

300

350

400

450

(Individual Test), o

F

Average Unexposed Wall Temperature Increase

0

50

100

150

200

0 50 100 150 200 250 300 350 400 450

Mean Average Tem

Average Temperature ase

250

perature Increase, o

F

 Incre

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10

14
standard deviation grows rapidly for all of the tests, especially for A1, A7 and A8, which reach 

standard deviations in excess of 200 o

F. This divergence is shown even more graphically in Fig. 

11, which is a plot of the average temperature increase on the unexposed wall for the individual 

specimen versus the mean value for the temperature increase of all of the tests. The spread in 

temperatures among the ten samples begins at around 170 o

F. At the 250 oF threshold, the 

standard deviation (shown as the double-ended red arrow in Fig. 11) is +/- 66 oF, and the 

maximum spread is almost 250 o

F. 

Peak Wall Temperatures

The temperature histories of all nine ASTM E119 thermocouples on the wall not exposed to the 

furnace are included in the appendix for the ten tests conducted. Because each furnace has a 

unique design and method of temperature control, it is not possible to predict which of the 

thermocouples positioned on the side of the wall that is unexposed to the flames will be the 

hottest. For most of the current testing, the temperature increase indicated by TC6 was within 

one minute of being the hottest, and for ease of comparison, this temperature increase is plotted 

in Fig. 12 for the ten furnace tests. The first laboratory for which TC6 reaches the criteria for 

failure, 325 o

F (dotted line in Fig. 10), is A7, at 62 minutes; laboratory A9 is the last, with TC6 

reaching 325 oF more than 10 minutes later. Note, however, that TC6 is not representative of the 

hottest temperature for this test; TC5 reaches the limit in A9 at 65 min. 

t 

any given time (regardless of thermocouple location) are plotted on the vertical axis in Fig. 13 

al, the 

 well 

e 

ases 

lim

The highest temperature increases measured on the unexposed surface of the wall assembly a

against the average of the ten tests on the horizontal scale. If all of the tests were identic

data would fall on the solid line. Up to a temperature increase of about 175 oF, the tests are

correlated; however, at higher values the maximum temperature increases at any given tim

diverge greatly, with a standard deviation of +/- 100 oF for mean high temperature incre

equal to the limiting temperature in ASTM E119-00 (the vertical red line at 325 o

F indicates the 

it). The range in peak temperature increases at this point is from 220 oF to 580 oF. 

Fire Resistance Ratings

The key output of ASTM E119-00 is the fire resistance rating. In all ten furnace tests, this wall 

design received a rating of 1-h. For five of the laboratories, the failure time was based upon the 

average temperature increase on the unexposed face exceeding 250 o

F. The maximum allo

individual temperature on the backside of the wall (325 oF) was the failure limit for f

laboratories, and one laboratory exceeded both criteria simultaneously (within the limit of

data rate). In no case was the wall breached in less than 70 minutes. The wall was not designed

to be loaded; hence, the failure to maintain a load was not examined. 

Table 3 displays these times, as well as the failure criteria. The overall average time to failu

was 65.0 minutes, with a standard deviation of 2.8 minutes. Laboratory A6 exceeded the

average by more than one standard deviation, and laboratories A7 and A8 were less that the 

average by more than one standard deviatio

wed 

our 

 their 

re 

tem re 

 res

n. The far right column indicates additional 

perature failure criteria that occurred within one minute of the first failure. Note that the fi

istance rating, shown in the second column, is the same for all nine laboratories: 1-h. 

15
Figure 12. Temperature increase of TC6 on unexposed side of each specimen tested 

sts

ASTM TC6

600

700

800

900

1000

o

F

Figure 13. Individual test unexposed surface peak temperature vs. mean of all ten te

0

100

200

300

400

0 10 20 30 40 50 60 70

Time, minutes

TC6

A1

A2

A3

A4

A5

500

 -Tamb,

A6

A7

A8

A9

A10

E119 limit

~55 ~ 65 Time, minutes

High TC Temperatures

500

600

l Tests), o

F

A1

A2

A3

0

0 100 200 300 400 500 600

Mean High Temperature Increase, o

F

High Te

100

200

300

mperature Increase

400

 (Individua

A4

A5

A6

A7

A8

A9

A10

16
Table 3. Summary of Failure Criteria 

Laboratory 

Fire 

Resistance 

Rating 

Time to First 

Failure, minutes

Failed 

Thermocouple 

Reading 

Other TC’s Failing

within 1 minute 

A1 1 hour 64 average TC3, 5, 7 

A2 1 hour 62.8 TC3 average 

A3 1 hour 66.8 average TC4, 6, 8 

A4 1 hour 67.5 average TC3, 6, 8 

A5 1 hour 65.8 average TC6 

A6 1 hour 70 TC3 TC4, 5, 6, 7, 

average 

A7 1 hour 60.6 TC7 TC3, 5, 6, average 

A8 1 hour 61.9 average TC3, 4, 6 

A9 1 hour 65.8 TC5 none 

A10 1 hour 65 average, TC5 TC4, 6, 7 

average 1 hour 65.0 +/- 2.8 average -- 

bly 

t of 

ters has 

rnace 

couples. 

ilure and 

e-tof

ANALYSIS OF RESULTS 

Even though all ten tests resulted in the same fire resistance rating for this generic wall assem

(1 h), it is important to identify the possible causes for the range of times to failure for this se

tests, especially considering how close to the minimum time (60 min) that several of the 

laboratories reported. The relationship between time to failure and the following parame

been examined: average furnace temperature, temperature-time integral, peak fu

temperature, and standard deviation of furnace temperature. 

Figure 14 is a plot of the difference between the average time-to-failure and the time-to-failure 

for a specific test, and the furnace temperature averaged over time for the control thermo

The failure time trends downward with increasing average furnace temperature, but the 

correlation is too small to be significant. The negative correlation between time-to-fa

the integral of temperature over time (Fig. 15) is also too small to be significant 

The difference between the average time-to-failure and the time-to-failure for a specific test, and 

the time-average of the highest temperature furnace control thermocouple exhibits a correlation

coefficient of R2

=0.36; too small to be significant. This is shown in Fig. 16. The average of the 

standard deviation across the furnace control thermocouples also has a correlation with tim

ailure (Fig. 17) too small to be significant. 

17
y = -0.0912x + 130.43

R2

 = 0.1609

-6

-4

-2

0

2

4

6

1400 1410 1420 1430 1440 1450

Average Furnace Temperature, o

F

Deviation in Time to Failure, min.

Figure 14. Correlation of deviation with average furnace temperature 

Figure 15. Correlation of deviation with temperature integral

Correlation of Time-to-failure with T-t Integral

y = -0.0015x + 0.0195

R2

 = 0.1905

-6

-4

-2

0

2

4

6

-1500 -1000 -500 0 500 1000 1500

Temperature Integral Deviation, o

F-min.

Deviation in Time to Failure, min.

18
igure 16 lation of de on with peak average furnace temp

y = x + 88.053

5

0

2

6

1420 1480 1500

Peak Av Furnace Tem o

F

re, .

 -0.0599

R2

 = 0.359

-6

-4

-2

ion in

4

min

1440 1460

erage 

1520

perature, 

Deviat Time to Failu

F . Corre viati erature 

6

 Ti n.

0

2

4

me to Failure, mi Deviation in

y = -0.104x + 3.3281

R2

 = 0.2931 -4

-2

-6

0 10 20 30 40 50 60

Std. Deviation of Average Furnace Temperatures, o

F

Figure 17. Correlation of deviation with standard deviation of average furnace temperature

19
F

Figure 18 shows that the initial ambient temperature does not correlate, to any significant degree, 

with the time-to-failure. Furnace pressure was not considered since the furnace pressures were 

not all taken at the same location in the furnace. Table 4 summarizes the results of these 

correlation studies, indicating that none of the correlations reached a statistically meaningful 

level of significance. 

In addition to the furnace parameters mentioned above, the time to failure in a given test can be 

influenced by the variations in the specimen materials, differences in specimen preparation and 

operating procedures, the furnace design, the instruments used to make the measurements, and 

their placement on the specimen and in the furnace. 

Table 4. Summary of correlations of failure time with furnace conditions 

Furnace Parameters Slope R2

igure 18. Correlation of deviation with laboratory ambient temperature

overall average of TCs -0.09 min/oF 0.16 

T-t deviation -0.0015 min/oF-min 0.19 

peak ave. TC -0.06 min/oF 0.36 

std. dev. of ave. TCs -0.10 min/oF 0.29 

ambient temperature -0.10 min/oF 0.13 

6

y = -0.1016x + 7.678

R2

 = 0.1345

-6

-4

-2

0

2

4

60 65 70 75 80 85 90 95

Ambient Laboratory Temperature, F

Deviation in Time to Failure, min.

20
SUMMARY OF RESULTS

A test program was conducted to examine the laboratory-to-laboratory variations associated with 

determining the fire resistance rating of a gypsum wall assembly using the test method 

prescribed in ASTM E119-00. The test program undertaken by the NAFTL consortium and 

described in this report is the first ever to target a fire test of this magnitude. 

The key results of the test program are summarized below: 

• The participating NAFTL laboratories arrived at an identical 1-h rating for the gypsum wall 

specimen tested according to ASTM E119-00 and using their respective standard operating 

protocols. 

• The variability among laboratories using their individual standard operating procedures and 

as close-to-identical as possible 1-h rated gypsum wall specimens was found to be 65 ± 2.8 

minutes. 

• The variability in individual peak thermocouple temperatures measured at similar locations 

on different 1-h rated gypsum wall assemblies exceeded ± 50 oF about one hour into the tests. 

• Individual thermocouples on the unexposed side of the 1-h rated gypsum wall differed in 

temperature by as much as 300 o

F at the average time of failure. 

• Differences in the time to failure for ten close-to-identical ASTME E119 wall assembly tests 

did not correlate at a statisti e furnace 

temperature, res, or standard 

deviation among the furnace control thermocouple temperatures. 

The six inter-laboratory tests conducted by the Japanese organizations yielded an average 

time to failure (based upon either the average unexposed wall temperature or the peak 

temperature measured by TC 6 or TC7) of 67.1 ± 1.1 minutes. 

cally significant level with differences in averag

the temperature-time integral, changes in ambient temperatu

•

 

21
22

REFERENCES 

ASTM E 119-00: "Standard Test Methods for Fire Tests of Building Construction Materials," 

ASTM International, West Conshohocken, PA, 2000. 

ASTM E 1269-01: “Standard Method for Determining Specific Heat Capacity by Differential 

Scanning Calorimetry,” ASTM International, West Conshohoken, PA, 2001. 

ASTM C1396-04: "Standard Specification for Gypsum Wallboard," ASTM International, West 

Conshohocken, PA, 2005. 

Bénichou, N., Sultan. M., “Thermal Properties of Lightweight-Framed Construction Components 

at Elevated Temperatures,” Fire and Materials, 29:165-179, 2005. 

Bentz, D.P., Flynn, D.R., Kim, J.H., Zarr, R.R., “A Slug Calorimeter for Evaluating the Thermal 

Performance of Fire Resistive Materials,” Fire and Materials 30:257-270, 2006. 

Grosshandler, W. (ed.), 2002, "Fire Resist. Determination and Perf. Prediction Research Needs 

Workshop: Proc.," NISTIR 6890, Nat. Inst. of Stds. and Technology, Gaithersburg, Sept. 

Grosshandler, W., 2006, "The Response of Structures to Fire -- Advances and Challenges in 

Predicting Behavior," Proceedings of the 13th International Heat Transfer Conference, Sydney. 

ISO/IEC 17025:1999(E), "General Requirements for the Competence of Testing and Calibration 

Laboratories," International Organization for Standardization, Geneva, 1999. 

ISO 834: "Fire resistance tests -- Elements of Building Construction," Parts 1-9 International 

Organization for Standardization, Geneva. 

Manzello, S.L., Gann, R.G., Kukuck, S., Lenhert, D., “The Influence of Gypsum Board Type (X 

Ra

or C) on Real Fire Performance of Partition Assemblies,” Fire and Materials 31:425-442, 2007. 

NFPA 251: "Standard Methods of Test of Fire Endurance of Building Construction Material" 

NFPA Int'l, Quincy, MA, 1999. 

machandran, V.S., Paroli, R.M., Beaudoin, J.J., Delgado, A.H., Handbook of Thermal 

analysis of Construction Materials. Noyes Publication, William Andrew Publishing. Norwich, 

NY 2003. 

UL 263: "Fire Tests of Building Construction and Materials," Underwriters Laboratories, 

Northbrook, IL, 1998. 
APPENDIX A. Plots of unexposed face thermocouples for laboratories A-1 through A-10 

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

0 10 20 30 40 50 60 70 80 90 100 110 120

Temperature (°F)

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-1)

Time (min)

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-2) 1300

0

100

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250

Time (

200

1

1

1200

min)

Temperature (

300

400

500

600

700

800

°F)

900

000

100

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

23
24

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-3)

1000

1100

1200

1300

0

0 10 20 30 40 50 60 70 80 90 100 110 120

Time (min)

100

200

300

400

500

600

700

Temperature (

800

900

) °F

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

0 10 20 30 40 50 60 70 80 90 100 110 120

Time (min)

Temperature (°F)

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

 TEMPERATURES VS. TIME (LAB A-4)

UNEXPOSED FACE THERMOCOUPLES
25

0

100

200

300

400

Temp

500

600

700

erature (°

800

900

F)

1000

1100

1200

1300

0 10 20 30 40 50 60 70 80 90 100 110 120

Time (min)

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-5)

Note: TC No. 6 malfunction from 00:05:00 to 

00:20:00. TC No. 8 malfunction from 00:05:00 to 

00:21:20. Both TC's removed from average for these 

i i d

0

100

200

300

400

500

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-6) 1300

TC 1

TC 2

1100

1200

TC 3

600

700

mperature (°

800

900

1000

F)

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

0 10 20 30 40 50 60 70 80 90 100 110 120

Time (min)

Te
26

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

Time (min)

Temperature (°F)

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-7)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

0 10 20 30 40 50 60 70 80 90 100 110 120

Time (min)

Temperature (°F)

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-8)
27

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

0 10 20 30 40 50 60 70 80 90 100 110 120

Time (min)

Temperature (°F)

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-9)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240

Time (min)

Temperature (°F)

TC 1

TC 2

TC 3

TC 4

TC 5

TC 6

TC 7

TC 8

TC 9

AVG

UNEXPOSED FACE THERMOCOUPLES

 TEMPERATURES VS. TIME (LAB A-10)
APENDIX B. Results from Japanese inter-laboratory test program 

In addition to the NAFTL members that participated in this effort, four Japanese laboratories 

joined in the testing. These include: The Center for Better Living, Japan Testing Center for 

Construction Materials, General Building Research Corporation of Japan, and Japan Housing 

and Wood Technology Center. The Japanese testing was coordinated through The Center for 

Better Living by Tensei Mizukami. Mr. Mizukami contacted several Japanese laboratories and 

worked with Dr. Manzello of NIST to have all necessary materials (gypsum board/steel studs) 

used for the NAFTL program exported from the USA to Japan. Dr. Manzello was also able to 

observe some of the tests that were conducted in Japan. A summary of data collected from the 

Japanese laboratories is included below. Although four laboratories participated, the Japan 

Testing Center for Construction Materials maintains more than one vertical furnace. 

Consequently, six tests were conducted in Japan.

The temperatures of the Japanese laboratory furnace tests, designated B1 through B6, are plotted 

in Fig. 1B. The dotted line represents the time-temperature curve specified in the ASTM E119-

00 standard. As can be seen, furnace B1 failed at approximately 20 minutes into the test. The 

furnace was subsequently brought on-line again within three minutes of the failure; the cause of 

failure is not known. 

Fig. 2B demonstrates how closely the furnace temperatures follow the standard temperature 

curve. One can see that during warm-up, the test furnaces deviate by as much as 300 o

F from the 

E119-00 temperature, and are most often on the low side. Very similar behavior was observed 

for the furnaces in North America. Due to failure of furnace B1, a large discrepancy was 

observed between the E119-00 temperature and furnace B1. 

Table 1B. Summary of failure criteria for Japanese laboratories 

Laboratory 

Fire 

Resistance 

Rating 

Time to First 

Failure, 

minutes 

Failed 

Thermocouple 

Reading 

Other TC’s Failing 

within 1 minute 

B1 1 hour 67.7 TC7 Ave., TC6 

B2 1 hour 67.3 TC7 Ave., TC6 

B3 1 hour 66.0 TC6 Ave. 

B4 1 hour 65.5 Ave. TC3, TC4, TC5, 

TC6, TC7 

B5 1 hour 68.0 Ave., TC6 TC4, TC5, TC7 

B6 1 hour 68.0 TC7 Ave. 

average 1 hour 67.1 ± 1.1 TC7, TC6, Ave -- 

28
0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 20 40 60 80 100 120

Time (min)

Temperature (°F)

B1

B2

B3

B4

B5

B6

ASTM E119

Figure 1B. Average temperature of each of six Japanese furnaces as a function of time 

Figure 2B. Individual Japanese furnace temperatures vs. prescribed ASTM E119 temperature 

0

200

400

600

800

1000

1200

1400

1600

1800

0 200 400 600 800 1000 1200 1400 1600 1800

A S T M E 119 T em perature,  ゚F

T est F urnace T em perature,  ゚F

B 1

B 2

B 3

B 4

B 5

B 6

29
The furnace pressure was recorded continuously for all of the six tests conducted by the Japanese 

laboratories, and these are plotted in Fig. 3B. The pressures (relative to the surrounding 

laboratory) remained fairly constant and slightly positive (except for furnace B1). This was in 

contrast to the North American furnace pressures which remained fairly constant and around 

zero during the tests. In any event, proper interpretation of these pressure data requires knowing 

the location of the probe in the furnace. 

The average temperature increase on the unexposed wall for each Japanese furnace test is shown 

in Fig. 4B. Note that the ambient temperature has been subtracted from the average temperatures. 

As mentioned earlier, one of the criteria for rating the fire resistance of a wall assembly is the 

time when the average temperature of the thermocouples on the unexposed side of the specimen 

reaches 250 o

F above its initial average temperature. This limit is shown as the dotted red line in 

Fig. 4B. Similar to the North American furnaces, the temperature profiles are closely grouped 

for the first 60 minutes and then begin to diverge. None of the average temperature increases 

exceed the threshold before 60 minutes, and all have exceeded the threshold by 70 minutes. 

Fig. 5B is a plot of the average temperature increase on the unexposed wall for the individual 

specimen versus the mean value for the temperature increase of all of the tests. The spread in 

temperatures among the six samples begins at around 170 o

F, which was very similar to the 

North American tests. Above these temperatures, the deviation among furnaces is quite large; 

more than 200 oF at later times. 

The key output of ASTM E119-00 is the fire resistance rating (Table 1B). For one of the 

Japanese furnaces, the failure time was based upon the average temperature increase on the 

unexposed face exceeding 250 oF. The maximum allowed individual temperature on the 

backside of the wall (325 o

F) was the failure limit for four Japanese furnaces; one furnace 

exceeded both criteria simultaneously (within the limit of their data rate). In no case was the 

wall breached in less than 70 minutes. The wall was not designed to be loaded; hence, the failure 

to maintain a load was not examined. 

It is useful to compare these results to the North American furnaces. For five of the North 

American furnaces, the failure time was based upon the average temperature increase on the 

unexposed face exceeding 250 oF. The maximum allowed individual temperature on the 

backside of the wall (325 o

F) was the failure limit for four North American furnaces, and one 

North American furnace exceeded both criteria simultaneously (within the limit of their data 

rate). 

In summary, Table 1B displays these times for the Japanese furnaces, as well as the failure 

criteria. The overall average time to failure was 67.1 minutes, with a standard deviation of 1.1 

minutes. For comparison, the North American furnaces resulted in an overall average time to 

failure was 65.0 minutes, with a standard deviation of 2.8 minutes. Similar to the North 

American furnace tests, the fire resistance rating, shown in the second column, is the same for all 

six Japanese furnaces: 1-h. 

30
F U R N A C E P S S U R E R E

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0 10 20 30 40 50 60 70

P ressure, in. of w ater

B 1

B 2

B 3

B 4

-0.250

-0.200

m e, m

B 5

B 6

T i inutes

d face of Japanese specimens

Figure 3B. Japanese furnace pressures as a function of time 

Figure 4B. Average ASTM TC increase on unexpose

0

0 10 20 30 40 50 60 70

Time (min)

100

200

Tav

300

e - Tambient (°F) 400

500

600

700

B1

B2

B3

B4

B5

B6 E119 limit

E119 limit

31
Figu ests 

0

100

200

300

400

500

600

0 100 200 300 400 500 600

M ean A ve. T em p. Increase,  ゚F

A ve. T em p. Increase (Individual T ests), 

 ゚F

B 1

B 2

B 3

B 4

B 5

B 6

S

re 5B. Individual test unexposed surface average temperature vs. mean of six Japanese t

32