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PUBLICATIONS

Kuunu-ROBIN measurements of the

APPARENT THERMAL CONDUCTIVITY

OF TWO REFRACTORY INSULATION

MATERIALS, USING HIGH- TEMPERATURE

GUARDED-HOT-PLATE APPARATUS

Jerome G. Hust

David R. Smith

National Bureau of Standards

U.S. Department of Commerce

Boulder, Colorado 80303-3328

April 1988

. U56

#88-3087

1988

c-2

Stimulating America's Progress 1913-1988

Research Information Center

National Bureau of Standards

Gaithersburg, Maryland 20099

NBSIR 88-3087

ROUND-ROBIN MEASUREMENTS OF THE

APPARENT THERMAL CONDUCTIVITY

OF TWO REFRACTORY INSULATION

MATERIALS, USING HIGH-TEMPERATURE

GUARDED-HOT-PLATE APPARATUS

Jerome G. Hust

David R. Smith

Chemical Engineering Science Division

Center for Chemical Engineering

National Engineering Laboratory

National Bureau of Standards

Boulder, Colorado 80303-3328

April 1988

Sponsored, in part, by

U.S. Department of Energy

Oak Ridge National Laboratory

Oak Ridge, Tennessee 37830

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Round-Robin Measurements of the Apparent

Thermal Conductivity of Two Refractory Insulation Materials,

sing High-Temperature Guarded-Hot-Plate Apparatus

Jerome G. Hust

and

David R. Smith

Center for Chemical Engineering

National Engineering Laboratory

National Bureau of Standards

Boulder, CO 80303-3328

This report presents the test results and analysis of round-robin

measurements of apparent thermal conductivity for two kinds of

refractory insulation board using high-temperature guarded-hotplate apparatus. The round robin was carried out under the sponsorship of the American Society for Testing and Materials (ASTM)

Subcommittee C-16.30 on Thermal Measurements. To complete the

measurement program in a timely manner the participants chose to

measure different specimens, selected, however, from the same production lot. The test results for apparent thermal conductivity

illustrate the interlaboratory reproducibility as well as the

temperature and density dependence. The data include the temperature range from 297 to 773 K. The standard deviation is 7.4% for

the 48 test results reported by seven participating laboratories

for fibrous alumina-silica. The standard deviation is 8.0% for

the 58 test results reported for calcium silicate.

Key words: apparent thermal conductivity; guarded-hot-plate apparatus; high-temperature; refractory thermal insulation; round robin

This work was funded, in part, by DOE/ORNL under contract ORNL/IA21428.

1
1 . Introduction

During the last 20 years considerable progress has been made in

developing and improving equipment and techniques for measuring

the thermal resistance of thermal insulations, particularly at

ambient temperatures. However, recent unpublished intercomparisons of measurements of apparent thermal conductivity obtained

with the Cl 77 test method [1] suggest that considerably larger

uncertainties may exist in measurements made with apparatus

designed for higher temperatures. As a consequence, a task group

was formed under the auspices of the American Society of Testing

and Materials, Subcommittee C-16.30, to perform a round-robin

measurement program using guarded-hot-plate apparatus at temperatures between ambient and about 775 K (500°C).

Because of the urgency of the need for this information, the

original plan, formulated in the fall of 1986, was to include only

three laboratories in the study. However, as interest grew the

task force decided in the spring of 1987 to include other laboratories, as long as they finished the measurements by July of 1987.

The objective was to have the preliminary analysis completed by

the 1987 fall ASTM meeting in Toronto, Canada. Such an ambitious

schedule for a round robin seemed unrealistic at the time, but

because of the intense interest and cooperation of the

participants the schedule has been achieved.

The participants in this round robin did not measure the same

specimen. Experience indicates that it usually takes a year or

longer for a single specimen to make the rounds of each

laboratory. Instead, round-robin specimens chosen from the same

production lot of one manufacturer were distributed to the

participants at the same time. This was felt by the participants

to be desirable in order to obtain data for comparing the

performance of the different laboratories in a timely manner.

2 . Scope

This report presents the results and analysis of apparent thermal

conductivity data obtained on two refractory insulation boards:

calcium silicate of two nominal densities and a fibrous aluminasilica insulation. The fibrous alumina-silica is also under

consideration for use as a Standard Reference Material (SRM) of

thermal resistance [2].

The specimens of these materials were supplied by two of the

participants. Prior to shipping the specimens to the participants, the bulk density of each specimen was measured at the

National Bureau of Standards, Boulder, Colorado (NBS/B). After

the specimens were measured by the participants and returned to

NBS/B, the apparent thermal conductivity of each specimen was

measured at 333 K using the NBS/B high-temperature guarded-hotplate apparatus in the single-sided mode.

2
The plate sizes of the guarded-hot-plate apparatus used by the

participants are listed in Table 1. The direction of heat flow

was vertical for each of the apparatus with the exception of that

having a plate diameter of 40.6 cm; for it the direction of heat

flow was horizontal.

Table 1

.

Sizes of plates in apparatus used by seven participants

in the round-robin measurement program.

Plate Size

(cm)

61.0x61.0

40.6 dia.

30.5x35.6

30.5x30.5

25.4 dia.

25.4 dia.

20.3 dia.

Metered Size

(cm)

30.5x30.5

20 . 3 dia.

15.2x15.2

15.2x15.2

12.7 dia

.

10 . 2 dia

.

10.2 dia.

3 . Experimental Data

The experimental data submitted by the participants were compiled

into tabular files for analysis by computer from the standardized

forms provided to the participants. Data submitted in engineering

units were converted to SI units for uniformity and ease of

intercomparison. Tables 2 and 3 respectively contain the data

supplied by the participants for apparent thermal conductivity of

fibrous alumina-silica and of calcium silicate. Throughout this

report the same symbol was used to represent the data from a given

participant. These symbols are listed below:

Lab 1=0 Lab 2 = a Lab 3 = Lab 4 = v

Lab 5=0 Lab 6 = + Lab 7 = X

4. Reference Equations and Data Analysis

For brevity, the term "thermal conductivity" will be used in place

of "apparent thermal conductivity" in the following text and

figures

.

In the analyses below, the integral method [3] was used in fitting

the equations. The deviations shown in the tables and the deviation plots are also calculated by the integral method. This was

done to remove any potential inconsistency caused by the presence

of both large and small temperature differences in the data set.

3
When fitting curves to experimental conductivity data we used

weighted least-squares fits; the weighting was chosen to minimize

the sum of the squares of the relative deviations, rather than the

sum of the absolute deviations. This is considered to be preferable because when measuring thermal conductivity the experimentalist tends to keep the relative (percentage) errors constant.

4.1 Fibrous alumina-silica

The reference equation used to analyze the round-robin data for

the fibrous alumina-silica specimens was based on measurements of

thermal conductivity performed by NBS on similar specimens in conjunction with an effort to establish this material as an SRM [2].

The measurements of the candidate SRM specimens were performed on

the same high-temperature guarded-hot-plate apparatus at NBS/B

used in measuring the round-robin specimens. The variation of

thermal conductivity with temperature for the candidate SRM

specimen is

k = 15.13 + 0.09489 T + 2.888x10-8 T3 , (1)

where k is in mW/(m- K) and T is in K. The coefficients in eq(l)

were obtained from a weighted least-squares fit of the data for a candidate SRM, for a specimen having a density of 247 kg/m3

, over

a range of mean temperatures from 313 to 773 K. Since the densities of the participants’ round-robin specimens varied from 207 to

237 kg/m3

, we assume that the dependence of thermal conductivity

on temperature for the round-robin specimens should be similar to

that of the SRM candidate material.

Equation (1) was fitted to the participants’ uncorrected data

listed in table 2, with a multiplicative coefficient determined by

a weighted least-squares fit to be 1.057. These data, along with

the fitted curve, eq(2), are shown in figure 1, The deviations of

the data from the curve are shown in figure 2. The standard

deviation of the data from the curve is 9.4%.

k = 1.057(15.13 + 0.09489 T + 2.888x10-8 T3

) , (2)

with k defined by this correlation for T varying from 313 to 773 K.

The data shown in figures 1 and 2 contain two broad classes or

components of variability, assumed to be independent. One component is due to the variability of measurement among different

apparatus and associated procedures, and the other is due to

variability among the specimens. It is desirable to minimize the

4
second component (specimen variability) so that the variability

can be accurately determined for the different apparatus used by

the participants in the round robin. NBS measured the thermal

conductivity of each round-robin specimen at a temperature of 333

K to permit correcting for the variability among specimens. The

resulting data (thermal conductivity measured by NBS) are listed

in table 4.

To perform these corrections, the mean value of the NBS data was

first obtained. The mean value of thermal conductivity for the

specimens used in the round robin (last thirteen results listed in

table 4) is 49.847 mW/(m-K). Next we calculated the percentage

difference between the thermal conductivity of each participant’s

specimen (or pair, more commonly) as measured by NBS, and the mean

value of the NBS data for all specimens. These percentage corrections, listed in table 6, represent estimates of the specimen

variability and were applied to the participants’ reported data

to remove the effect of this variability. For example, if the

thermal conductivity of a given specimen, as measured by NBS,

deviated by +5% from the mean value for all specimens, the value

reported by the participant was corrected by dividing it by a factor of 1.05.

Equation (1), shifted by a multiplier determined from a weighted

least-squares fit to be 1.082, was fitted to the corrected data.

The result is

k = 1.082(15.13 + 0.09489 T + 2.888x10-8 T3 ) . (3)

with k defined by this correlation for T varying from 313 to 773 K.

These corrected data, along with the curve calculated from eq(3),

are shown in figure 3. The deviations of the corrected data from

the curve are shown in figure 4 and listed in the last column of

table 2. The standard deviation of these data from eq(3) is 7.4%,

as compared to the value of 9.4% obtained with the uncorrected

data.

The correction procedure is based on two assumptions: (a) the

correction is independent of temperature, and (b) the correction

is independent of the metered area. The first assumption appears

to be approximately valid since the reported data form a family of

curves that with one exception are parallel to each other. Data

reported by Lab 1 are the exception. The validity of the second

assumption is assessed by examining the density dependence of the

NBS data at 333 K for the round-robin specimens.

5
The specimens used to determine the density dependence ranged in

density from 207 to 308 kg/m3 . A reference equation describing

the dependence of thermal conductivity on density is given in

reference [2]. This reference equation is

k = 41.89 + 0.03344 D, (4)

where k is in mW/(m- K) , and D is in kg/m3 . The thermal

conductivity data on which this relation is based were obtained on

the NBS/B high-temperature guarded-hot-plate apparatus for 16

different specimens varying in density from 218 to 308 kg/m3 . The data in table 4, including the density data, used to obtain

the coefficients for eq(4), are those obtained at NBS/B by

measuring each of the specimens used in the round robin. These

data are illustrated in figure 5. The deviations of the data from

eq(4) are shown in figure 6 and listed in the last column of table

4. It was necessary to measure six additional specimens (first

six lines of table 4) to obtain information on the depen-dence of

thermal conductivity on density; this was not possible using only

round-robin specimens because of the large scatter in the data and

the limited range of density represented by the round-robin set.

The large amount of scatter in the corrected data illustrated in

figures 5 and 6 is evidence that the thermal conductivity of these

alumina-silica specimens is strongly affected by characteristics

other than bulk density. As a consequence, the second assumption

regarding uniformity over various metered areas becomes questionable. This leads to the conclusion that the 7.4% standard deviation of the corrected data may be caused both by variability among

specimens as well as procedures of participating laboratories. We

are unable to separate these two components at the present time.

It has been suggested that curves of thermal conductivity vs.

density for this material may have considerably different slopes

at different temperatures; such a conclusion is precluded here

because of insufficient information obtained in this round robin

and because of the scatter in the data obtained. The desire to

obtain "pilot" information quickly left little time for investigating in depth many questions arising from this study. Future

round robins involving this material should be planned with time

enough to investigate the reasons for the scatter seen here.

6
4.2 Calcium silicate

A reference equation describing the dependence on temperature of

the thermal conductivity for the calcium silicate specimens was

obtained. It was based on measurements performed by NBS/B (Lab 7)

on one specimen from the same lot from which the participants’

round-robin specimens were chosen. The coefficients in eq(5) were

obtained from a weighted least-squares fit of these data.

k = 68.48 + 0.01820 T + 5.616x10-8 T3 , (5)

where k is in mW/(ra- K) and T is in K. This correlation is

defined for values of T ranging from 333 to 701 K.

Equation (5) was fitted to the participants’ uncorrected data

listed in table 3, with a multiplicative coefficient determined by

a weighted least-squares fit to be 1.032. These data, along with

the fitted curve, eq(6), are shown in figure 7. The deviations of

the data from the curve are shown in figure 8. The standard

deviation of the data from the curve is 7.9%.

k = 1.032(68.48 + 0.01820 T + 5.616x10-8 T3 ) , (6)

with k defined by this correlation for T varying from 313 to 773 K

The data shown in figures 7 and 8 contain two components of

variability. One is due to the apparatus measurement variability,

and the other is due to specimen variability. It is desirable to

minimize the second component so that the variability can be

accurately determined for the different apparatus used by the

round-robin participants. NBS/B measured the thermal conductivity

of each round-robin specimen to permit correcting for the

variability among specimens. The resulting data are listed in

table 3. The same method used to perform the corrections for the

previously discussed alumina-silica specimens was used at this

point to obtain the corrections for the calcium silicate.

The mean value of thermal conductivity for the specimens used in

the round robin (results listed in table 5) is 74.991 mW/(m-K). A

value was calculated for the percentage difference between the

thermal conductivity, measured by NBS/B, of each specimen (or

pair) used by each participant and the mean value for the NBS/B

data for all specimens. These percentage corrections, listed in

table 6, representing estimates of the specimen variability, were

applied to the reported data to remove the effect of this

variability.

7
Equation (6), shifted by a multiplier determined by a weighted

least-squares fit to be 1.033, was fitted to the corrected data.

The result is

k = 1.033(68.48 +0.01820 T + 5.616x10-8 T3 ) , (7)

defined for T varying from 313 to 773 K.

These corrected data along with the curve calculated from eq(7)

are shown in figure 9. The deviations of the data from the curve

are shown in figure 10 and listed in the last column of table 3.

The standard deviation of. these data from the reference curve is

8 . 0 %.

The correction procedure is based on two assumptions: (a) the

correction is independent of temperature, and (b) the correction

is independent of the metered area. The first assumption appears

to be reasonably valid since the reported data form a family of

curves that are parallel to each other, within their scatter with

one exception. Data from Lab 5 cross the fitted line as temperature increases, but otherwise lie within the scatter of the band

of data.

The validity of the second assumption is assessed by examining the

density dependence of the NBS/B data at 333 K for the round-robin

specimens. The specimens used in the round robin study ranged in

density from 324 to 446 kg/m3 . A reference equation describing

the dependence of thermal conductivity on density was obtained.

The reference equation chosen is

k = 44.37 + 0.07694 D, ( 8 )

where k is in mW/(m-K), and D is in kg/m3 and varies over the

range from 324 to 446 kg/m3 . The data in table 5 used to obtain the coefficients for eq(8) are

those measured at NBS/B on each of the specimens used in the round

robin. These data are illustrated in figure 11. The deviations of

the data from eq(8) are shown in figure 12 and listed in the last

column of table 5.

From the amount of scatter illustrated in figures 11 and 12, it is

suggested that the thermal conductivity of these calcium silicate

specimens is affected mainly by their bulk density and not appreciably by other characteristics as were the specimens of fibrous

alumina-silica. The second assumption involves the implicit assumption that density does not vary appreciably with metered area.

8
To shed light on this question, the variation of density within

one large, square specimen of calcium silicate was measured. Its

edges originally measured 61 cm. It had been cut into four square

pieces measuring 25.4 cm on each side, four rectangular pieces

25.5 cm by 9.8 cm, and one square piece measuring 10 cm on each

side. The densities of these pieces ranged from 443.5 to 449.0

kg/m3

, with a mean density of 447.4 kg/m3 and standard deviation

of 0.6%. This standard deviation in density corresponds to a standard deviation of about 0.3% in apparent thermal conductivity,

according to eq(8) or figure 11. This suggests that only a small

portion of the 8% standard deviation of the corrected data is

caused by residual variations in density of the specimens.

It is puzzling that the standard deviation for the corrected data,

8.0%, is not less than that of the uncorrected data, 7.9%. It is

known that calcium silicate insulation board contains not only

adsorbed moisture (as do all porous materials), but also water of

crystallization. Adsorbed moisture can be driven off reversibly

by heating a specimen to a temperature somewhat above 100° C.

Water of crystallization, on the other hand, is chemically bonded

and requires higher temperatures to remove; its removal is an irreversible process. This means that the thermal conductivity

obtained for this material could depend on the history of the

material: its past temperature and environmental humidity could

influence the amount of adsorbed moisture present as well as the

amount of water of crystallization.

The fact that the correction procedure does not bring the roundrobin data closer together may be evidence of variation among

different preparation and measurement procedures used by the

partipants. The mean value of thermal conductivity measurements

on the specimens by NBS, 75 mW/(m- K) at 333 K, differed from the

mean value by the participants. This mean value can be estimated

from the fitted curve in figure 9 to be approximately 79 mW/(m- K)

at 333 K, greater by about 5% than the mean of the NBS

measurements

.

While specific instructions for preparation of the specimens were

given to the participants in the round robin, some participants

lacked the equipment required to comply with all the instructions

regarding conditioning of the specimens. This might explain some

of the scatter in the data about the fitted curve. In this

regard, the purpose of the round robin may have been fulfilled: to

compare the best efforts of the participating laboratories, as

well as to learn how suitable either material would be as an SRM

for high temperatures

.

Figures 7 through 10 show that both the reported and the corrected

data from one lab (squares) for calcium silicate are in considerable disagreement with the other data. For comparison, the

standard deviation of the subset of data defined by omitting the

results on calcium silicate for Lab 3 was calculated; it is 60%

for uncorrected data and 5.8% for the corrected data.

9
5. Summary and Conclusions

Round-robin measurements of thermal conductivity are presented for

two refractory insulation materials at temperatures from 297 to

773 K. Reference equations are given describing the temperature

and density dependencies of the thermal conductivity of the two

materials. These equations are used to analyze the interlaboratory measurement reproducibility of the seven laboratories that

participated in the round robin.

The reproducibility, as measured by two times the standard

deviation of the corrected data, is 15% and 16% for fibrous

alumina-silica and calcium silicate, respectively. As was

suggested by previous unpublished data, this is considerably

larger than the 2% reproducibility observed with ambienttemperature apparatus [4]. However, the variability of the

corrected data for alumina-silica probably contains a significant

portion due to residual specimen variability. This excessive

residual specimen variability is a consequence of the tight schedule established for this round robin. Discussions with the

participants established, however, that the round robin provided

useful initial information. Any future high-temperature round

robins should be preceded by careful fabrication and selection of

the specimens to assure their greater uniformity and thermal

stability. Even though the different laboratories had guardedplate apparatus of different sizes and shapes, it may be possible

to arrange a procedure so that several labs measure the same

specimen, as is usual.

After the data from the different labs were corrected there

remained an equally large scatter about the fitted correlation and

inconsistent dependences with temperature; this indicates that

a high-temperature SRM for thermal resistance could be very useful

to laboratories measuring apparent thermal conductivity at

temperatures significantly higher than room temperature.

We gratefully acknowledge the generosity of two companies for

donating the insulation specimens for this round robin: Manville

Corporation of Denver, CO, for donating the alumina-silica specimens, and PABCO of Fruita, CO, for donating the calcium silicate

specimens. We also acknowledge the time and effort spent by the

participating laboratories: CertainTeed Corporation, Blue Bell,

PA; Dynatech R/D Company, Cambridge, MA; Fiberglas Canada, Inc.

,

Sarnia, Ontario; Manville Corporation, Denver, CO; National Bureau

of Standards, Boulder, CO; Owens/Corning Fiberglas Corporation,

Granville, OH; and PABCO, Fruita, CO.

10
6 . References

[1] ASTM Standard Test Method Cl 77 for STEADY-STATE HEAT FLUX

MEASUREMENTS AND THERMAL TRANSMISSION PROPERTIES BY MEANS OF THE

GUARDED-HOT-PLATE APPARATUS, ANNUAL BOOK OF ASTM STANDARDS . Vol

.

04.06, pp. 21-36 (ASTM, Philadelphia, 1986)

[2] Hust, Jerome G. and Smith, David R. , Fibrous alumina-silica

insulation board as a candidate Standard Reference Material, to be

published as an NBSIR

[3] Hust, J. G. and Lankford, A. B. , Comments on the measurement

of thermal conductivity and presentation of a thermal conductivity

integral method, International Journal of Thermophysics, Vol. 3,

No. 1, pp. 67-77, 1982

[4] Hust, J. G. and Pelanne, C. M. , Round robins on the apparent

thermal conductivity of low-density glass fiber insulations using

guarded hot plate and heat flow meter apparatus, U.S. Nat. Bur.

Stand. NBSIR 85-3026 (1985)

11
Table 2. Round-robin thermal conductivity data for fibrous aluminasi I i ca

.

Lab

.

No. Spec imen

I dent

.

Test Dens i ty

( kg/m3)

H i gh

Temp

.

(K)

Low Temp

.

(K)

Mean

Temp.

(K)

Thermo 1 Conduct

.

(mW/m.K)

Pet. Dev

.

1 17A20 232.3 672.039 623.150 647.594 85.019 -1.34

1 17A20 232.3 787 . 039 742.761 764.900 93.089 -9.37

1 17A20 232.3 443 . 650 392.706 418.178 69.889 20.28

2 00A24 237.7 361 .533 311.283 336.408 55.997 8.78

2 00A24 237.7 504.844 453.744 479.294 74.601 9.39

2 00A24 237.7 669.956 619.522 644.739 100.265 11.58

2 00A24 237.7 598.933 547.856 573.394 79.039 -1 .40

2. 00A22 241 .7 364.872 314.644 339.758 55.954 4.35

2 00A22 241 .7 504.444 453.450 478.947 74.154 5.21

2 00A22 241 .7 669 . 800 619.578 644.689 96.518 3.88

2 00A22 241 .7 599.456 548.217 573.836 80.436 -3.04

3 05A07 218.2 497.761 447.261 472.511 58.216 -9.59

3 05A07 218.2 597.039 547.317 572.178 70.321 -8.05

3 05A07 218.2 697.594 648.650 673.122 81.417 -9.27

3 05A07 218.2 796.261 746.372 771 .317 92.656 -10.73

3 05A07 218.2 623.150 522.817 572.983 67.439 -11.97

3 05A07 218.2 673.539 474.428 573.983 68.015 -11.51

4 02A12 225.9 308.094 286.317 297.206 53.605 4.56

4 02A12 225.9 354.928 324.872 339 . 900 59.369 5.24

4 02A12 225.9 365.317 315.761 340.539 58.937 4.32

4 02A12 225.9 392.539 292.206 342 . 372 58.937 3.87

4 02A12 225.9 427 . 650 326.594 377.122 63.548 4.12

4 02A12 225.9 528.039 327.483 427.761 69.168 2.38

4 02A12 225.9 552.983 303.372 428.178 69.024 1 .97

4 02A12 225.9 391 .094 291 .372 341 .233 57.496 1.58

5 23A25 219.6 393.150 353.150 373.150 57.000 8.97

5 23A25 219.6 493.150 453.150 473.150 67.000 5.65

5 23A25 219.6 593.150 553.150 573.150 83.000 10.16

5 23A25 219.6 693.150 653.150 673.150 96.000 8.76

5 23A25 219.6 793.150 753.150 773.150 115.000 12.34

5 23A25 219.6 423.150 323.150 373.150 56.000 7.01

5 23A25 219.6 523.150 423.150 473.150 66.000 4.03

5 23A25 219.6 623.150 523.150 573.150 81 .000 7.46

5 23A25 219.6 723.150 623.150 673.150 99.000 12.10

6 06A10 224.3 310.983 286.206 298.594 50.003 -2.64

6 06A10 224.3 422.706 286.817 354.761 56.487 -2.95

6 06A10 224.3 561 .983 287.706 424.844 63.548 -5.45

6 06A10 224.3 643.539 288.372 465.956 68.159 -6.36

6 06A10 224.3 310.428 286.261 298.344 47.841 -6.80

7 21A30 237.0 343.294 323.089 333.192 52.767 6.70

7 DXA30 247.0 323.055 303.134 313.095 45.769 -3.22

7 28A30 247.2 383.227 363.068 373.148 51 .939 -3.50

7 28A30 247.0 463.157 383.201 423.179 57.251 -3.72

7 28A30 246.8 562.750 383.205 472.978 62.786 -3.91

7 28A30 246.5 662.267 402.976 532.622 69.619 -4.23

7 28A30 246.3 603.096 562.959 583.028 75.939 -3.62

7 28A30 246.1 653.224 613.126 633.175 82.732 -3.10

7 28A30 245.8 712.137 672.899 692.518 91 .822 -1 .83

7 28A30 245.6 763.373 728.645 746.009 96.895 -4.32

12
Table 3. Round-robin thermal conductivity data for calcium s

Lab. Specimen Test

No . I dent . Dens i ty

( kg/m3)

1 6A8M12 443.7

1 6A8M12 443.7

1 6ASM 12 443.7

1 6A8M12 443.7

2 1M12 403.2

2 1M1

2

403.2

2 1M12 403.2

2 1M1

2

403.2

2 9L1 320.2

2 9L1 320.2

2 9L12 320.2

2 9L12 320.2

3 5A7M12 450.

1

3 5A7M12 450.1

3 5A7M12 450.1

3 5A7M12 450.1

4 1A2M24 440.5

4 1A2M24 440.5

4 1A2M24 440.5

4 1A2M24 440.5

4 1A2M24 440.5

4 1A2M24 440.5

4 1A2M24 440.5

4 1A2M24 440.5

4 1A2L12 358.8

4 1A2L12 358.8

4 1A2L12 358.8

4 1A2L12 358.8

4 1A2L12 358.8

4 1A2L12 358.8

4 1A2L12 358.8

4 1A2L12 358.8

5 2A4M12 393.8

5 2A4M12 393.8

5 2A4M12 393.8

5 2A4M12 393.8

5 2A4M12 393.8

5 2A4M12 393.8

5 2A4M12 393.8

5 2A4M12 393.8

5 2A4M12 393.8

6 3A9M12 405.3

6 3A9M12 405.3

6 3A9M12 405.3

6 3A9M12 405.3

7 4M24AC 443.4

7 4M24AC 443.4

7 4M24AC 446.2

7 4M24AC 446.0

7 4M24AC 445.8

7 4M24AC 445.3

7 4M24AC 444.6

7 4M24AC 444.0

7 4M24AC 444.0

7 4M24AC 443.9

7 4M24AC 443.3

7 4M24AC 444.6

7 4M24AC 446.2

H i gh Low

T emp

.

Temp

.

(K) (K)

757. 539 729. 872

648. 261 617. 261

529. 983 495. 372

430. 650 392. 539

376. 372 327. 078

503. 289 453. 111 669. 583 619. 567

598. 967 548. 422

377. 528 326. 678

503. 361 452. 367

669. 739 619. 789

598. 656 547. 867

497. 650 446. 650

596. 650 548. 594

694. 928 647. 317

795. 094 747. 317

308. 039 286. 317

354. 428 323. 428

365. 594 316. 039

391 . 539 292. 150

427. 483 326. 761

528. 428 327. 817

552. 094 305. 039

391 . 539 291 . 706

307. 817 286. 039

354. 594 324..983

365.,761 315..872

391 .,150 291 ..372

428..150 326..761 527..817 327.,761

552..594 303,.317

391 .317 292..483

393..150 353 .150

493..150 453 .150

593..150 553 .150

693..150 653 .150

793..150 753 .150

423 .150 323 .150

523 .150 423 .150

623 .150 523 .150

723 .150 623 .150

308 .317 286 .261 444 .206 287 .150

570 .428 288 .039

308 .539 286 .261

712 .221 676 .060

709 .587 675 .964

343 .094 323 .193

373 .165 343 .174

413 .320 373 .226

472 .770 433 .164

572 .831 523 .279

649 .749 599 .268

674 .786 575 .638

722 .322 535 .621 714 .678 687 .533

572 .532 523 .148

343 .097 323 .136

Mean The irma 1 Temp. Conduc t

.

(K) (mW/m.K)

743. 706 119. 891

632. 761 108. 507

512. 678 98. 564

41 1 . 594 90. 639

351 . 725 89. 529

478. 200 96. 706

644. 575 108. 911

573. 694 95. 394

352. 103 78. 621

477. 864 86. 374

644. 764 101 . 403

573. 261 85. 336

472. 150 70..177

572. 622 73.,491 671 . 122 84..875

771 . 206 92.,944

297. 178 81 ..849

338. 928 86..748

340. 817 85..740

341 . 844 85..740

377. 122 89..054

428.,122 91 .504

428..567 91 .359

341 . 622 84 .154

296..928 75 .076

339..789 79 .111 340..817 78 .679

341 .261 78 .390

377..456 81 .561 427 .789 85 .019

427 .956 84 .587

341 .900 76 .661

373 .150 75 . 000

473 .150 88 .000

573 .150 99 . 000

673 .150 110 .000

773 .150 126 . 000

373 .150 74 .000

473 .150 85 .000

573 .150 95 .000

673 .150 108 .000

297 .289 73 .779

365 .678 79 .543

429 .233 83 .866

297 .400 73 .203

694 .141 99 .568

692 .776 100 .543

333 . 144 76 .586

358 .170 77 .854

393 .273 79 .620

452 .967 82 . 649

548 .055 88 .069

624 .509 92 .888

625 .212 92 . 408

628 .972 94 .149

701 . 106 101 .322

547 .840 87 .593

333 . 117 75 .778

i I i cate

.

Pet. Dev

.

8.76

9.81

10.08

8.19

1 1 .95 12.22

10.55

3.02

7.79

9.93

12.85

1 .10

19.50

21 .79 17.28

•18.29

.18 4.13

2.82

2.72

4.76

4.30

3.95

.83

.87 4.20

3.57

3.12

5.30

6.40

5.68

.81 -6.67

3.11

7.64

9.36

12.98

-7.96

-.47

3.22

7.29

-5.71

-1 .78 -.53

-6.45

-4.52

-3.45

-4.24

-3.86

-3.52

-3 38

-3 81 -4 87

-5 48

-4.25

-3.51

-4.31

-5.24

13
i 4. Test resu 1 1 s for each of the round-robin a 1 urn i na-s

i

1 i ca specimens as obta i ned by NBS at a mean temperature of 333

Spec imen Test H i gh Low Mean The rma

1

Pet

.

I dent

.

Dens i ty Temp. Temp

.

T emp

.

Conduct

.

Dev

.

( kg/m3) (K) (K) (K) (mW/m.K)

3-28/30 247.3 343.187 323.111 333.149 47.771 -5.00

3-28/30 247.4 343.207 323.167 333 . 1 87 47.973 -4.57

11-35 295.1 343.197 323.181 333 . 1 89 53.019 2.38

11-36 295.8 343.108 323.179 333.144 53.220 2.70

IV-1 306.5 343.314 323.067 333.191 50.737 -2.76

IV—

3

307.7 343.376 323.117 333.247 50.622 -3.08

CBRD-21 237.0 343.294 323.089 333.192 52.767 5.59

CBRD-22 221.4 343.399 323.157 333.278 50.941 3.23

CBRD-24 236.4 343.316 323.063 333.190 49.257 -1 .09

CBRD-12 225.7 343.232 323.107 333.170 54.394 9.11

CBRD-02 223.4 343.468 323.028 333.248 52.766 6.45

CBRD-10 225.0 343 . 440 323.069 333.255 53.653 7.90

CBRD-06 220.5 343.169 323.126 333.148 53 . 359 7.68

CBRD-17 220.1 343.154 323.113 333.134 46.837 -5.15

CBRD-20 217.4 343.341 323 . 1 60 333.251 47.229 -4.09

CBRD-23 207.2 343.179 323.082 333.131 46.464 -5.07

CBRD-25 207.9 343.224 323.076 333.150 46.176 -5.77

CBRD-05 214.2 343.506 323.168 333.337 48.033 -2.12

CBRD-07 215.3 343.309 323.003 333.156 46.140 -6.39

i 5. Test resu 1 1 s for each of the round— robin calcium si 1 i cate

spec i mens as obta i ned by NBS at a mean temperalture of 333

Specimen Test High Low Mean The irmal Pet. Ident

.

Dens i ty Temp. Temp. Temp

.

Conduct

.

Dev

.

( kg/m3) (K) (K) (K) (mW/m.K)

4M24 446. 2 343. 097 323.,136 333. 117 75..778 -3 .86

9L1

2

324. 1 343. 316 323. 236 333. 276 68..456 -1 .24

1M12 386. 2 343. 129 323.,144 333. 137 75.,075 1 .32

2M1

2

404. 5 343. 245 323..145 333.,195 75..177 - .42

4M1 2 404. 5 343. 252 323..151 333. 202 74..036 -1 .97

2M24 426. 9 343. 150 323.,131 333..141 79..006 2 .27

1 M24 425. 4 343. 137 323..138 333.,138 78..408 1 .67

2L1 2 354. 9 343. 291 323..111 333..201 71 ..057 - .87

1 LI 2 354. 4 343. 139 323..125 333..132 72..357 .99 9M1 2 403. 4 343. 296 323..084 333..190 74,.631 -1 .04

3M1 2 400. 5 343. 149 323..106 333..128 76..108 1 .21 8M1 2 405. 1 343. 114 323..097 333.,106 75..701 .21 6M1

2

409. 8 343. 125 323..126 333..126 76..554 .85

5M1 2 409. 3 343. 149 323..140 333..145 75..785 - .10

7M12 412. 1 343. 225 323 .093 333 .159 76 .731 .85

14
Table 6. Percentage Corrections Applied to Reported Data

to Remove Effect of Specimen Variability

Percentage Correction

Lab No. Alumina-Silica Calcium Silicate

1 +5.65 -1.52

2* -2.19

+1.19

+8.71

-0.11

3 +5.54 -1.69

4* -7.48 +4.38

-4.96

5 +7.08 +0.51

6 -7.33 -0.51

7 +4.39 -1.05

*Two separate specimens were measured by lab 2 (both

specimen) and by lab 4 (calcium silicate only)

15
Apparent

Thermal

Conduc

t

l

vl

ty,

mU/m

.

250 300 350 400 450 500 550 600 650 700 750 800

Temperature, K

Figure 1. Thermal conductivity of round-robin specimens of fibrous alumina-silica; test densities range from 218 to

247 kg/m3 . The solid curve is calculated from eq (2).

16
250 300 350 400 450 500 550 600 650 700 750

Temperature, K

Figure 2. Deviations of thermal conductivity round-robin test

results from values calculated with eq(2) for fibrous

alumina-silica.

17
Apparent

Thermal

Conduct

ivl

ty

,

mN/m.

250 300 350 400 450 500 550 600 650 700 750 800

Temperature, K

Figure 3. Thermal conductivity round-robin test results, c°r

~ rected for deviation of apparent thermal conductivity

from mean thermal conductivity, 49.9 mW/m.K, for fibrous alumina-silica; test densities range from 218 to

247 kg/m3 . The solid curve is calculated from eq (3).

18
)

100/x

o

o

u

a

> o

o

IS) JDO

250 300 350 400 450 500 550 600 650 700

Temperature, K

750 800

Figure 4. Deviations of corrected thermal conductivity round - robin test results from values calculated with eq (3)

for fibrous alumina-silica.

19
200 210 220 230 240 250 260 270 280 290 300 310

DENSITY, kg/m3

Figure 5. Thermal conductivity of round-robin specimens of fibrous alumina-silica as measured by NBS at a mean temperature of 333 K. The solid curve is calculated from

eq (4).

20
VOOI (

10

7.5 -

2.5

o

o

.<

I V) X

o

-2.5

-5

-7.5

i i i o

o

o

, , I .

o

o

o

o

o

o

200 210 220 230 240 250 260

DENS 1 TY , kg/

m

270

3

280 290 300 310

Figure 6. Deviations of thermal conductivity of round-robin

specimens of fibrous alumina-silica from values

calculated with eq (4).

21
Apparent

Thermal

Conduct

l

vl

tij

,

mW/m

.

Temperature, K

Figure 7. Thermal conductivity of round-robin specimens of calcium silicate; test densities range from 320 to 450

kg/m3 . The solid curve is calculated from eq (6).

22
VOOI (

Temperature, K

Figure 8. Deviations of thermal conductivity round-robin te3t

results from values calculated with eq (6) for calcium

silicate.

23
Apparent

Thermal

Conductivity

250 300 350 400 450 500 550 600 650 700 750 80

0

Temperature, K

Figure 9. Thermal conductivity round-robin test results, corrected for deviation of apparent thermal conductivity

from mean thermal conductivity, 75.0 mW/m.K, for calcium silicate; test densities range from 320 to 450

kg/m3 . The solid curve is calculated from eq (7).

24
)

100/x

Temperature, K

Figure 10. Deviations of corrected thermal conductivity roundrobin test results from values calculated with eq ( 7

)

for calcium silicate.

25
Rpparent

Thermal

Conductlvl

Figure 11. Thermal conductivity of round-robin specimens of calcium silicate as measured by NBS at a mean temperature

of 333 K. The solid curve is calculated from eq (8).

26
Figure 12. Deviations of thermal conductivity of round-robin

specimens from values calculated with eq (8) for

calcium silicate.

27

U.S. DEPT. OF COMM. 1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. Publication Date BIBLIOGRAPHIC DATA

SHEET (See instructions) NBSIR 88-3087 April 1988

4. TITLE AND SUBTITLE

Round-Robin Measurements of the Apparent Thermal Conductivity of Two Refractory

Insulation Materials, Using High-Temperature Guarded-Hot-Plate Apparatus

5. AUTHOR(S)

Jerome G. Hust and David R. Smith

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) C~ nntrarf /

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

ORNL/IA - 21428

8

.

Type of Report & Period Covered

9.

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

U.S. Department of Energy

Oak Ridge National Laboratory

P.O. Box X

Oak Ridge, TN 37830

10.

SUPPLEMENTARY NOTES

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

11.

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

bibliography or literature survey, mention it here)

This report presents the test results and analysis of round-robin measurements of apparent thermal conductivity for two kinds of refractory insulation

board using high-temperature guarded-hot-plate apparatus. The round robin was carried out under the sponsorship of the American Society for Testing and Materials (ASTM) Subcommittee C-16.30 on Thermal Measurements. To complete the

measurement program in a timely manner the participants chose to measure different specimens, selected, however, from the same production lot. The test

results for apparent thermal conductivity illustrate the inter-laboratory re- producibility as well as the temperature and density dependence. The data include the temperature range from 297 to 773 K. The standard deviation is 7.4/

for the 48 test results reported by seven participating laboratories for fibrous

alumina-silica. The standard deviation is 8.0% for the 58 test results reported

for calcium silicate.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key word'. : , apparent thermal conductivity; guarded-hot-plate apparatus; high temperature;

refractory thermal insulation; round robin

13.

AVAILABILITY

|X^ Uni imited |~] For Official Distribution. Do Not Release to NTIS

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

20402.

14. NO. OF

PRINTED PAGES

32

15. Price

[X3§Order From National Technical Information Service (NTIS), Springfield, VA. 22161

U.S. Government Printing Office: 1988—575-379/85 14^