ASTM C653-97
(Guide)Standard Guide for Determination of the Thermal Resistance of Low-Density Blanket-Type Mineral Fiber Insulation
Standard Guide for Determination of the Thermal Resistance of Low-Density Blanket-Type Mineral Fiber Insulation
SCOPE
1.1 This guide describes the calculation and interpolation of a thermal resistance value for low-density blanket-type insulation material at a particular density and thickness having been selected as representative of the product. It requires measured values of this average density and thickness, as well as apparent thermal conductivity values determined by either Test Method C177 or C518.
1.2 This guide applies to a density range for mineral-fiber material of roughly 6.4 to 48 kg/m (0.4 to 3.0 lb/ft ). It is primarily intended to apply to low-density, mineral-fiber mass insulation batts and blankets, exclusive of any membrane facings. Apparent thermal conductivity data for these products are commonly reported at a mean temperature of 23.9°C (75°F) and a hot-to-cold plate temperature difference of 27.8°C (50°F) or 22.2°C (40°F).
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 653 – 97
Standard Guide for
Determination of the Thermal Resistance of Low-Density
Blanket-Type Mineral Fiber Insulation
This standard is issued under the fixed designation C 653; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This guide describes the calculation and interpolation of 3.1 Definitions—For definitions used in this guide, refer to
a thermal resistance value for low-density blanket-type insula- Terminology C 168.
tion material at a particular density and thickness having been 3.2 Definitions of Terms Specific to This Standard:
selected as representative of the product. It requires measured 3.2.1 apparent thermal conductivity, l—the ratio of the
values of this average density and thickness, as well as specimen thickness to thermal resistance of the specimen. It is
apparent thermal conductivity values determined by either Test calculated as follows:
Method C 177, C 518, or C 1114.
l5 L/R W/m·k! or ~Btu · in./ft ·h·F! (1)
~
1.2 This guide applies to a density range for mineral-fiber
3 3
3.2.1.1 Discussion—For this type of material an expression
material of roughly 6.4 to 48 kg/m (0.4 to 3.0 lb/ft ). It is
for the apparent thermal conductivity as a function of density
primarily intended to apply to low-density, mineral-fiber mass
is:
insulation batts and blankets, exclusive of any membrane
facings. Apparent thermal conductivity data for these products l5 a 1 bD 1 c/D (2)
are commonly reported at a mean temperature of 23.9°C (75°F)
where a, b, c 5 parameters characteristic of a product, and
and a hot-to-cold plate temperature difference of 27.8°C (50°F)
related to the conductivity of the gas, the conductivity of the
or 22.2°C (40°F). 3
solid and the conductivity due to radiation.
1.3 This standard does not purport to address all of the
3.3 Symbols:Symbols—The symbols used in this guide have
safety concerns, if any, associated with its use. It is the
the following significance:
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
2 2
R 5 thermal resistance, (m K/W) or (h·ft F/Btu)
bility of regulatory limitations prior to use.
l5 apparent thermal conductivity, (W/m·K) or (Btu·in/
2. Referenced Documents
h·ft F)
2 2
Q/A 5 heat flow per unit area, (W/m ) or (Btu/h·ft )
2.1 ASTM Standards:
3 3
D 5 bulk density of a specimen, (kg/m ) or (lb/ft )
C 167 Test Methods for Thickness and Density of Blanket
2 L 5 measured specimen thickness, (m) or (in.)
or Batt Thermal Insulations
T 5 apparatus plate temperature, (K) or (F)
C 168 Terminology Relating to Thermal Insulating Materi-
L8 5 specimen thickness if the sample from which the
als
specimen is selected does not recover to label
C 177 Test Method for Steady-State Heat Flux Measure-
thickness, (m) or (in.)
ments and Thermal Transmission Properties by Means of
s 5 estimate of the standard deviation for a set of data
the Guarded-Hot-Plate Apparatus
points
C 518 Test Method for Steady-State Heat Flux Measure-
D5 apparatus systematic error
ments and Thermal Transmission Properties by Means of
C5 overall uncertainty in a measured R-value
the Heat Flow Meter Apparatus
3.3.1 Subscripts:
C 1045 Practice for Calculating Thermal Transmission
Properties from Steady-State Heat Flux Measurements
C 1114 Test Method for Steady-State Thermal Transmission 5 signifies average of a lot
av
Properties by Means of the Thin-Heater Apparatus 5 refers to hot surface
H
5 refers to cold surface
C
This guide is under the jurisdiction of ASTM Committee C-16 on Thermal
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurement.
Current edition approved Feb. 10, 1997. Published June 1997. Originally Rennex, Brian G., “Thermal Parameters as a Function of Thickness for
published as C 653 – 70. Last previous edition C 653 – 92. Combined Radiation and Conduction for Low-Density Insulation,” Journal of
Annual Book of ASTM Standards, Vol 04.06. Thermal Insulation, July 1979.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 653
5.2 In order to account for the variation in l-value due to
5 refers to test specimen
T
product density variability, measure a minimum of three “l
5 refers to nominal property for the product, as shown
N
versus D” data points on three different samples. This repre-
on the product label
5 refers to a set of data points sents nine data points for the “l versus D” curve. Again, this “l
i
5 refers to a particular specimen versus D” curve is developed to determine the l-value at a
s
particular representative density characteristic of a lot of
4. Significance and Use
material.
4.1 This guide provides a method to determine the thermal
5.3 The size of a lot of material to be characterized, the
performance of low-density blanket-type insulation. It may be
amount of material measured for the representative values of
used for the purposes of quality assurance, certification, or
density and thickness, and the frequency of tests all depend on
research.
the user’s needs, which could be related to quality assurance by
4.2 The thermal resistance of low-density insulation de-
a manufacturer, certification, or research.
pends significantly on the density, the thickness, and thermal
conductivity. Typical low-density, mineral-fiber insulation for
6. Procedure
buildings may vary in density from one specimen to the next.
6.1 This procedure uses nine {l ; D } data points all
i i
4.3 Thermal tests are time-consuming in comparison with
measured at the same hot and cold plate temperatures, to
density and thickness measurements. Low-density insulation
establish an interpolation equation for the determination of the
material is produced in large quantities. A typical lot would be
l-value at the average density, D . That is, the subscript i
av
a truckload or the amount necessary to insulate a house. th
refers to the i test point. The D is the average density of the
i
4.4 The relatively low unit cost of this product and the
specimen within the apparatus meter-area. The thermal resis-
relatively high cost of thermal resistance testing makes it
tance at L and D is as follows:
av av
cost-effective to test only a small percentage of the product
R 5 L /l (3)
av av av
area. It is recommended that there be a determination of the
6.2 Before the set of “apparent thermal conductivity versus
density that is representative of a lot by the measurement of the
average density of a statistically representative sampling. test density (l versus D )” data points can be measured on an
i i
apparatus, it is necessary to choose the test densities and
4.5 A fewer number of thermal measurements are then made
thicknesses. Three procedures for this choice are described in
to determine the apparent thermal conductivity at the previ-
ously determined representative density. The essential signifi- Annex A1.
cance of this guide is that a large lot of variable material is best 6.2.1 Procedure A—A single test specimen is compressed to
characterized by: (a) determining the representative density, obtain different densities (A1.2). This procedure offers the
and by (b) determining the thermal property at this represen- advantage of less test time to obtain three test points.
tative density with a small number of thermal measurements.
6.2.2 Procedure B—A different specimen is used for each
4.6 Building insulation products are commonly manufac- test point (A1.3). This method has the advantage of a better
tured in thicknesses ranging from 19 to 330 mm (0.75 to 13 in.)
statistical sampling with regard to material variability.
inclusive. Experimental work has verified that there is a 6.2.3 Procedure C—Test at D thereby eliminating the
av
dependence of l on thickness for some low density materi-
need for an interpolation (A1.4).
app
als.
6.3 Obtain a test value for l at each of the three densities.
4.7 The upper limit of test thickness for specimens evalu-
These three sets of test values result in three equations of the
ated using Test Methods C 177, C 518, and C 1114 is estab-
form of Eq 2 in 3.2.2. These are solved simultaneously to
lished based upon the apparatus design, overall dimensions,
determine the values of a , b , and c corresponding to
s s s
expected thermal resistivity level and desired target accuracy.
specimen s (see A2.1.2).
The testing organization is responsible for applying these
NOTE 1—Small errors in the measured values of l will result in large
restrictions when evaluating a product to ensure that the results
variations in the values of a, b, and c. Even so, the uncertainty of the
meet applicable product labels and any existing regulatory
interpolated value of l will be comparable to the measured error in l.
requirements.
6.4 Whenever possible, calculate running averages for the
4.8 Extrapolation of the apparent thermal conductivity or
specific product lot based on a number N equal to 20 or more
the thermal resistance beyond the ranges of thickness or
sets of product curve parameters (a;b;c ). Remember from
s s s
density of products tested is not valid.
6.3 that each of these sets requires three test points (see
5. Sampling
A2.1.3).
6.4.1 A larger number N results in more consistent values
5.1 For low-density mineral-fiber insulation, a lot sample
for a, b, and c; a smaller N represents a more current data base.
size of 75 to 150 ft is recommended to determine the average
6.5 In 6.3 a set of parameter values was calculated, and in
density, D . Density is determined by using Test Method
av
6.4 a running average was calculated. This section describes
C 167; take care to avoid the use of damaged material.
how to obtain an interpolation curve (or equivalently a set of
interpolation curve parameters) for the next sample, s, when it
Albers, M. A., and Pelanne, C. M., “An Experimental and Mathematical Study
has been possible to previously obtain a running average set, (
of the Effect of Thickness in Low-Density Glass-Fiber Insulation,” Proceedings,
¯ ¯
a¯; b; c¯). The given values are the set { a¯; b; c¯} and the
Seventeenth International Thermal Conductivity Conference, J. G. Hust, Ed.,
Plenum Press, 1983, pp. 471–482. measured values of l at three densities, D .
i i
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 653
NOTE 2—Parameter c is expected to account for most of the variation in
input data from either Test Method C 177, C 518, or C 1114.
the “l versus D” curve from specimen to specimen. When the density is
8.5 The material variability is partly taken into account by
3 3
less than 16 kg/m (1 lb/ft ), c is the dominant parameter causing the
the l versus D curve. When different specimens are tested there
variance of l from specimen to specimen. Then the previously determined
will be an amount of variation about the average l versus D
values, a¯, and b are used, along with a measurement of l at a particular
curve in addition to the apparatus precision. This additional
density, to calculate a value of c for a particular specimen, s. In order to
variation is here called the material variability and is desig-
have a better estimate of the mean, the value of c is thusly determined for
nated by s .
m
three values of density resulting in the value c¯ . The interpolation to the l
s
8.6 The total “repeatability” uncertainty on a l versus D
value at the average density, D , is calculated as follows, using Eq 3.
av
graph will be the sum of the aforementioned uncertainties and
is designated by s .
¯
l
l 5 a¯ 1 bD 1 c¯ /D (4)
s av s av
2 2 0.5
s 5 ~s 1 s ! (6)
l a m
An example of this calculation is in A2.1.4
8.7 In order to know what s is, it is necessary to plot a
l
6.6 Compute the average value of l¯ based on as many
av
number of l versus D test points. Twenty or more points are
values of l that have been determined. Remember from 6.3
s
recommended. It is then possible to determine by a graphical or
and 6.5 that three test points are required to obtain a value for
a mathematical method (see Annex A3) what is the 1s band
l . Common practice is to base an average l¯ on three values
within which 68 % of the points lie or what is the 2s band
av av
of l . within which 95 % of the points lie.
s
8.8 When more than one apparatus is used to develop the l
6.7 Calculate the R-value, R , of the product at the average
av
versus D curve, there will be a difference between the average
density and thickness (see Section 5 and A1.1) as follows:
values on the same set of specimens due to a systematic
R 5 L /l (5)
av T av difference among the apparatus.
8.9 The measured data from an apparatus have associated
with it an estimate of the possible systematic error in l of that
7. Report
apparatus. It is designated by D and is provided as input from
l
7.1 The report shall contain the following information: Test Method C 177, C 518, or C 1114.
8.10 For the purposes of this guide the overall accuracy, C ,
l
7.1.1 The values of the average thermal resistance, density
of the reported l-value is the sum of the overall repeatability
and thickness, the sample size, and the supporting data.
(1s for a 68 % confidence band) and the apparatus systematic
7.1.2 The test methods used and the information on the
error.
values and uncertainties of apparent thermal conductivity and
C 5 s 1D (7)
l l l
density that is required in Test Method C 167, C 177, C 518, or
8.11 The percent “precision and bias” uncertainties in the
C 1114.
reported R-value is calculated as follows, based on Eq 1:
7.1.3 The procedure used to obtain the l versus D curve
R 5 L /l (8)
av T av
along with the equation for the curve itself.
8.11.1 The estimate of the residual standard deviation of L
av
and l is made by statistical methods (see Annex A3). The
av
8. Precision and Bias
percent residual standard deviation in the reported R-value is
then:
8.1 There are a number of ways to combine the systematic
2 2 0.5
s s s
and random uncertainties that contribute to an overall uncer- R L l
5 1 (9)
S 2 2D
R
av L l
tainty of a measured quantity. The following procedure is T r
intended as a guideline.
8.11.2 In order to calculate the percent bias uncertainty in
R , it is necessary to obtain from Test Meth
...
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