ASTM C653-97(2002)
(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 C 177, C 518, or C 1114.
1.2 This guide applies to a density range for mineral-fiber material of roughly 6.4 to 48 kg/m3 (0.4 to 3.0 lb/ft3). 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:C653–97 (Reapproved 2002)
Standard Guide for
Determination of the Thermal Resistance of Low-Density
Blanket-Type Mineral Fiber Insulation
This standard is issued under the fixed designation C653; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 Thisguidedescribesthecalculationandinterpolationof 3.1 Definitions—For definitions used in this guide, refer to
a thermal resistance value for low-density blanket-type insula- Terminology C168.
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
apparentthermalconductivityvaluesdeterminedbyeitherTest calculated as follows:
Method C177, C518, or C1114.
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
material of roughly 6.4 to 48 kg/m (0.4 to 3.0 lb/ft ). It is
3.2.1.1 Discussion—For this type of material an expression
primarily intended to apply to low-density, mineral-fiber mass
for the apparent thermal conductivity as a function of density
insulation batts and blankets, exclusive of any membrane
is:
facings.Apparent thermal conductivity data for these products
l5 a 1 bD 1 c/D (2)
arecommonlyreportedatameantemperatureof23.9°C(75°F)
andahot-to-coldplatetemperaturedifferenceof27.8°C(50°F)
where a, b, c =parameters characteristic of a product, and related to
or 22.2°C (40°F).
the conductivity of the gas, the conductivity of the solid and the
1.3 This standard does not purport to address all of the conductivity due to radiation.
safety concerns, if any, associated with its use. It is the
3.3 Symbols:
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
2 2
R = thermal resistance, (m K/W) or (h·ft F/Btu)
bility of regulatory limitations prior to use.
l = apparent thermal conductivity, (W/m·K) or (Btu·in/
2. Referenced Documents
h·ft F)
2 2
Q/A = heat flow per unit area, (W/m ) or (Btu/h·ft )
2.1 ASTM Standards:
3 3
D = bulk density of a specimen, (kg/m ) or (lb/ft )
C167 Test Methods for Thickness and Density of Blanket
2 L = measured specimen thickness, (m) or (in.)
or Batt Thermal Insulations
2 T = apparatus plate temperature, (K) or (F)
C168 Terminology Relating to Thermal Insulation
L8 = specimen thickness if the sample from which the
C177 Test Method for Steady-State Heat Flux Measure-
specimen is selected does not recover to label
ments and Thermal Transmission Properties by Means of
thickness, (m) or (in.)
the Guarded-Hot-Plate Apparatus
s = estimate of the standard deviation for a set of data
C518 Test Method for Steady-State Thermal Transmission
points
Properties by Means of the Heat Flow Meter Apparatus
D = apparatus systematic error
C 1045 Practice for Calculating Thermal Transmission
C = overall uncertainty in a measured R-value
Properties from Steady-State Conditions
3.3.1 Subscripts:
C 1114 TestMethodforSteady-StateThermalTransmission
Properties by Means of the Thin-Heater Apparatus
= signifies average of a lot
av
= refers to hot surface
H
This guide is under the jurisdiction of ASTM Committee C16 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 C653–70. Last previous edition C653–92. Combined Radiation and Conduction for Low-Density Insulation,” Journal of
Annual Book of ASTM Standards, Vol 04.06. Thermal Insulation, July 1979.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C653–97 (2002)
density, D . Density is determined by using Test Method
= refers to cold surface
av
C
C167; take care to avoid the use of damaged material.
= refers to test specimen
T
5.2 In order to account for the variation in l-value due to
= refers to nominal property for the product, as shown
N
on the product label product density variability, measure a minimum of three “l
= refers to a set of data points versus D” data points on three different samples. This repre-
i
= refers to a particular specimen
sentsninedatapointsforthe“lversusD”curve.Again,this“l
s
versus D” curve is developed to determine the l-value at a
4. Significance and Use
particular representative density characteristic of a lot of
4.1 This guide provides a method to determine the thermal material.
performance of low-density blanket-type insulation. It may be
5.3 The size of a lot of material to be characterized, the
used for the purposes of quality assurance, certification, or amount of material measured for the representative values of
research.
density and thickness, and the frequency of tests all depend on
4.2 The thermal resistance of low-density insulation de- theuser’sneeds,whichcouldberelatedtoqualityassuranceby
pends significantly on the density, the thickness, and thermal
a manufacturer, certification, or research.
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.Atypical lot would be
l-value at the average density, D . That is, the subscript i
a truckload or the amount necessary to insulate a house. av
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
area. It is recommended that there be a determination of the R 5 L /l (3)
av av av
densitythatisrepresentativeofalotbythemeasurementofthe
average density of a statistically representative sampling.
6.2 Before the set of “apparent thermal conductivity versus
4.5 Afewernumberofthermalmeasurementsarethenmade
test density (l versus D)” data points can be measured on an
i i
to determine the apparent thermal conductivity at the previ-
apparatus, it is necessary to choose the test densities and
ously determined representative density. The essential signifi-
thicknesses. Three procedures for this choice are described in
canceofthisguideisthatalargelotofvariablematerialisbest
Annex A1.
characterized by: (a) determining the representative density,
6.2.1 ProcedureA—Asingletestspecimeniscompressedto
and by (b) determining the thermal property at this represen-
obtain different densities (A1.2). This procedure offers the
tative density with a small number of thermal measurements.
advantage of less test time to obtain three test points.
4.6 Building insulation products are commonly manufac-
6.2.2 Procedure B—A different specimen is used for each
turedinthicknessesrangingfrom19to330mm(0.75to13in.)
test point (A1.3). This method has the advantage of a better
inclusive. Experimental work has verified that there is a
statistical sampling with regard to material variability.
dependence of l on thickness for some low density materi-
6.2.3 Procedure C—Test at D thereby eliminating the
app
av
als.
need for an interpolation (A1.4).
4.7 The upper limit of test thickness for specimens evalu-
6.3 Obtain a test value for l at each of the three densities.
ated using Test Methods C177, C518, and C1114 is estab-
These three sets of test values result in three equations of the
lished based upon the apparatus design, overall dimensions,
form of Eq 2 in 3.2.2. These are solved simultaneously to
expected thermal resistivity level and desired target accuracy.
determine the values of a , b , and c corresponding to
s s s
The testing organization is responsible for applying these
specimen s (see A2.1.2).
restrictionswhenevaluatingaproducttoensurethattheresults
NOTE 1—Small errors in the measured values of l will result in large
meet applicable product labels and any existing regulatory
variations in the values of a, b, and c. Even so, the uncertainty of the
requirements.
interpolated value of l will be comparable to the measured error in l.
4.8 Extrapolation of the apparent thermal conductivity or
6.4 Whenever possible, calculate running averages for the
the thermal resistance beyond the ranges of thickness or
specific product lot based on a number N equal to 20 or more
density of products tested is not valid.
sets of product curve parameters (a;b;c ). Remember from
s s s
6.3 that each of these sets requires three test points (see
5. Sampling
A2.1.3).
5.1 For low-density mineral-fiber insulation, a lot sample
6.4.1 A larger number N results in more consistent values
size of 75 to 150 ft is recommended to determine the average
for a, b,and c;asmaller Nrepresentsamorecurrentdatabase.
6.5 In 6.3 a set of parameter values was calculated, and in
6.4 a running average was calculated. This section describes
Albers, M.A., and Pelanne, C. M., “An Experimental and Mathematical Study
how to obtain an interpolation curve (or equivalently a set of
of the Effect of Thickness in Low-Density Glass-Fiber Insulation,” Proceedings,
interpolation curve parameters) for the next sample, s, when it
Seventeenth International Thermal Conductivity Conference, J. G. Hust, Ed.,
Plenum Press, 1983, pp. 471–482. has been possible to previously obtain a running average set,
C653–97 (2002)
¯ ¯
8.5 The material variability is partly taken into account by
( a¯; b; c¯). The given values are the set { a¯; b; c¯} and the
the lversusDcurve.Whendifferentspecimensaretestedthere
measured values of l at three densities, D.
i i
will be an amount of variation about the average l versus D
NOTE 2—Parameter cisexpectedtoaccountformostofthevariationin
curve in addition to the apparatus precision. This additional
the “l versus D” curve from specimen to specimen. When the density is
3 3 variation is here called the material variability and is desig-
less than 16 kg/m (1 lb/ft ), c is the dominant parameter causing the
nated by s .
varianceof lfromspecimentospecimen.Thenthe previously determined
m
values, a¯, and b are used, along with a measurement of l at a particular
8.6 The total “repeatability” uncertainty on a l versus D
density, to calculate a value of c for a particular specimen, s. In order to
graph will be the sum of the aforementioned uncertainties and
have a better estimate of the mean, the value of c is thusly determined for
is designated by s .
l
three values of density resulting in the value c¯ .The interpolation to the l
s
2 2 0.5
value at the average density, D , is calculated as follows, using Eq 3.
s 5 ~s 1 s ! (6)
av
l a m
¯
l 5 a¯ 1 bD 1 c¯ /D (4)
s av s av
8.7 In order to know what s is, it is necessary to plot a
l
number of l versus D test points. Twenty or more points are
An example of this calculation is in A2.1.4
recommended.Itisthenpossibletodeterminebyagraphicalor
6.6 Compute the average value of l¯ based on as many
av
a mathematical method (see Annex A3) what is the 1s band
values of l that have been determined. Remember from 6.3
s
within which 68% of the points lie or what is the 2s band
and 6.5 that three test points are required to obtain a value for
within which 95% of the points lie.
l .Commonpracticeistobaseanaverage l¯ onthreevalues
av av
of l . 8.8 When more than one apparatus is used to develop the l
s
6.7 Calculate the R-value, R , of the product at the average versus D curve, there will be a difference between the average
av
density and thickness (see Section 5 and A1.1) as follows: values on the same set of specimens due to a systematic
difference among the apparatus.
R 5 L /l (5)
av T av
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 C177, C518, or C1114.
7.1.1 The values of the average thermal resistance, density
8.10 Forthepurposesofthisguidetheoverallaccuracy, C ,
l
and thickness, the sample size, and the supporting data.
of the reported l-value is the sum of the overall repeatability
7.1.2 The test methods used and the information on the
(1s for a 68% confidence band) and the apparatus systematic
values and uncertainties of apparent thermal conductivity and
error.
densitythatisrequiredinTestMethodC167,C177,C518,or
C 5s 1D (7)
l l l
C 1114.
7.1.3 The procedure used to obtain the l versus D curve
8.11 The percent “precision and bias” uncertainties in the
along with the equation for the curve itself.
reported R-value is calculated as follows, based on Eq 1:
8. Precision and Bias
R 5 L /l (8)
av T av
8.1 There are a number of ways to combine the systematic
and random uncertainties that contribute to an overall uncer-
8.11.1 Theestimateoftheresidualstandarddeviationof L
av
tainty of a measured quantity. The following procedure is
and l is made by statistical methods (see Annex A3). The
av
intended as a guideline.
percent residual standard deviation in the reported R-value is
8.2 The term precision is used in this guide in the sense of
then:
repeatability. The estimation of the standard deviation, s, for a
2 2 0.5
s s s
R L l
set of measurements with a normal distribution is the plus and
5 1 (9)
S 2 2D
R
av L l
minus range about an average value or curve, within which
T r
68% of the observations lie. The s is used to quantify the
8.11.2 In order to calculate the percent bias uncertainty in
precision.
R , it is necessary to obtain from Test Method C167 the
v
8.3 The term bias as used in this guide represents the total
estimate of systematic uncertainty in the measurement of L .
av
uncertainty in a set of measurements, including apparatus
This is of the order of the resolution of the measurement
systematicerror,apparatusprecision,andthematerialvariabil-
device, and it is designated here by D . For the purpose of this
L
ity.
gu
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