ASTM E1530-99

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Designation: E 1530 – 99
Standard Test Method for
Evaluating the Resistance to Thermal Transmission of
Materials by the Guarded Heat Flow Meter Technique
This standard is issued under the fixed designation E 1530; 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 E 220 Method for Calibration of Thermocouples by Com-
parison Techniques
1.1 This test method covers a steady-state technique for the
E 1142 Terminology Relating to Thermophysical Proper-
determination of the resistance to thermal transmission (ther-
ties
mal resistance) of materials in thicknesses of less than 25 mm.
E 1225 Test Method for Thermal Conductivity of Solids by
For homogeneous opaque solid specimens of a representative
Means of the Guarded-Comparative-Longitudinal Heat
thickness, thermal conductivity can be determined (see Note
Flow Technique
1). This test method is useful for materials having a thermal
−4 2
F 104 Classification System for Nonmetallic Gasket Mate-
resistance in the range from 10 to 400 3 10 m ·K/W thermal
rials
conductivity in the approximate range, 0.1< l < 30 W/(m·K)
F 433 Practice for Evaluating Thermal Conductivity of
over the approximate temperature range from 150 to 600 K. It
Gasket Materials
can be used ouside these ranges with reduced accuracy for
thicker specimens and for thermal conductivity values up to 60
3. Terminology
W/(m·K).
3.1 Definitions of Terms Specific to This Standard:
NOTE 1—A body is considered homogeneous when the preceding
3.1.1 heat flux transducer (HFT)—a device that produces an
property is found by measurement to be independent of specimen
electrical output that is a function of the heat flux, in a
dimensions.
predefined and reproducible manner.
1.2 This test method is similar in concept to Test Method
3.1.2 thermal conductance (C)—the time rate of heat flux
C 518, but is modified to accommodate smaller test specimens,
through a unit area of a body induced by unit temperature
having a higher thermal conductance. In addition, significant
difference between the body surfaces.
attention has been paid to ensure that the thermal resistance of
3.1.2.1 average temperature—the average temperature of a
contacting surfaces is minimized and reproducible.
surface is the area-weighted mean temperature of that surface.
1.3 The values stated in SI units are to be regarded as
3.1.3 thermal conductivity (l)—(of a solid material)—the
standard.
time rate of heat flow, under steady conditions, through unit
1.4 This standard does not purport to address all of the
area, per unit temperature gradient in the direction perpendicu-
safety concerns, if any, associated with its use. It is the
lar to the area:
responsibility of the user of this standard to establish appro-
3.1.3.1 apparent thermal conductivity—When other modes
priate safety and health practices and determine the applica-
of heat transfer through a material are present in addition to
bility of regulatory limitations prior to use.
conduction, the results of the measurements performed in
accordance with this test method will represent the apparent or
2. Related Documents
effective thermal conductivity for the material tested.
2.1 ASTM Standards:
3.1.4 thermal resistance (R)—the reciprocal of thermal
C 518 Test Method for Steady-State Heat Flux Measure-
conductance.
ments and Thermal Transmission Properties by Means of
3.2 Symbols:
the Heat Flow Meter Apparatus
3.2.1 l—thermal conductivity, W/(m·K) (Btu·in./h·ft ·°F).
2 2
C 1045 Practice for Calculating Thermal Transmission
3.2.2 C—thermal conductance, W/(M ·K) (Btu/(h·ft ·°F).
2 2
Properties Under Steady-State Test Conditions
3.2.3 R—thermal resistance, m ·K/W (h·ft ·°F/Btu).
3.2.4 Dx—specimen thickness, mm (in.).
2 2
3.2.5 A—specimen cross-sectional area, m (ft )
This test method is under the jurisdiction of ASTM Committee E37 on Thermal
Measurements and is the direct responsibility of Subcommittee E37.05 on Thermo-
physical Properties.
Current edition approved March 10, 1999. Published September 1999. Originally Annual Book of ASTM Standards, Vol 14.03.
published as E 1530 – 93. Last previous edition E 1530 – 93. Annual Book of ASTM Standards, Vol 14.02.
2 5
Annual Book of ASTM Standards, Vol 04.06. Annual Book of ASTM Standards, Vol 09.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E1530–99
3.2.6 Q—heat flow, W (Btu/h). through the specimen, the HFT and the interfaces between the
3.2.7 f—heat flux transducer output, mV. specimen and the apparatus. The proportionality is obtained
3.2.8 N—heat flux transducer calibration constant, through prior calibration of the system with specimens of
2 2
W/(m )·mV (Btu/h·ft ·mV). known thermal resistance measured under the same conditions,
2 2
3.2.9 Nf—heat flux, W/m (Btu/h·ft ). such that contact resistance at the surface is made reproducible.
3.2.10 DT—temperature difference,° C °F.
5. Significance and Use
3.2.11 Tg—temperature of guard heater, °C °F.
5.1 This test method is designed to measure and compare
3.2.12 Tu—temperature of upper heater, °C (°F).
3.2.13 Tl—temperature of lower heater, °C (°F). thermal properties of materials under controlled conditions and
their ability to maintain required thermal conductance levels.
3.2.14 T —temperature of one surface of the specimen, °C
(°F).
6. Apparatus
3.2.15 T —temperature of the other surface of the speci-
men, °C (°F). 6.1 A schematic rendering of a typical apparatus is shown in
Fig. 1. The relative position of the HFT to sample is not
3.2.16 Tm—mean temperature of the specimen, °C (°F).
3.2.17 —unknown specimen. important (it may be on the hot or cold side) as the test method
s
3.2.18 —known calibration or reference specimen. is based on maintaining axial heat flow with minimal heat
r
3.2.19 —contacts. losses or gains radially. It is also up to the designer whether to
o
choose heat flow upward or downward or horizontally, al-
4. Summary of Test Method
though downward heat flow in a vertical stack is the most
4.1 A specimen and a heat flux transducer (HFT) are common one.
sandwiched between two flat plates controlled at different 6.2 Key Components of a Typical Device (The numbers 1 to
temperatures, to produce a heat flow through the test stack. A 22 in parentheses refer to Fig. 1):
reproducible load is applied to the test stack by pneumatic or 6.2.1 The compressive force for the stack is to be provided
hydraulic means, to ensure that there is a reproducible contact by either a regulated pneumatic or hydraulic cylinder (1) or a
resistance between the specimen and plate surfaces. A cylin- spring loaded mechanism. In either case, means must be
drical guard surrounds the test stack and is maintained at a provided to ensure that the loading can be varied and set to
uniform mean temperature of the two plates, in order to certain values reproducibility.
minimize lateral heat flow to and from the stack. At steady 6.2.2 The loading force must be transmitted to the stack
state, the difference in temperature between the surfaces through a gimball joint (2) that allows up to 5° swivel in the
contacting the specimen is measured with temperature sensors plane perpendicular to the axis of the stack.
embedded in the surfaces, together with the electrical output of 6.2.3 Suitable insulator plate (3) separates the gimball joint
the HFT. This output (voltage) is proportional to the heat flow from the top plate (4).
FIG. 1 Key Components of a Typical Device
E1530–99
6.2.4 The top plate (assumed to be the hot plate for the 6.3.2 Reproducible load of 0.28 MPa (40 psi) has been
purposes of this description) is equipped with a heater (5) and found to be satisfactory for solid samples. Minimum load shall
control thermocouple (6) adjacent to the heater, to maintain a not be below 0.07 MPa (10 psi).
certain desired temperature. (Other means of producing and 6.3.3 Temperature sensors are usually fine gage or small-
maintaining temperature may also be used as long as the diameter sheath thermocouples, however, ultraminiature resis-
requirements in 6.3 are met.) The construction of the top plate tance thermometers and linear thermistors may also be used.
is such as to ensure uniform heat distribution across its face 6.3.4 Operating range of a device using a mean temperature
contacting the sample (8). Attached to this face (or embedded guard shall be limited to from −100 to 300°C, when using
in close proximity to it) in a fashion that does not interfere with thermocoupules as temperature sensors, and from −180 to
the sample/plate interface, is a temperature sensor (7) (typi- 300°C with platinum resistance thermometers.
cally a thermocouple, thermistor) that defines the temperature
7. Sampling and Conditioning
of the interface on the plate side.
6.2.5 The sample (8) is in direct contact with the top plate
7.1 Cut representative test specimens from larger pieces of
on one side and an intermediate plate (9) on the other side.
the sample material or body.
6.2.6 The intermediate plate (9) is an optional item. Its
7.2 Condition the cut specimens in accordance with the
purpose is to provide a highly conductive environment to the
requirements of the appropriate material specifications if any.
second temperature sensor (10), to obtain an average tempera-
ture of the surface. If the temperature sensor (10) is embedded 8. Test Specimen
into the face of the HFT, or other means are provided to define
8.1 The specimen to be tested should be representative for
the temperature of the surface facing the sample, the use of the
the sample material. The recommended specimen configura-
intermediate plate is not mandatory.
tion is a 50.86 0.25-mm (2 6 0.010-in.) diameter disk, having
6.2.7 The heat flux transducer (HFT) is a device that will
smooth flat and parallel faces, 6 0.025 mm (6 0.001 in.), such
generate an electrical signal in proportion to the heat flux
that a uniform thickness within 0.025 mm (6 0.001 in.) is
across it. The level of output required (sensitivity) greatly
attained in the range from 0.5 to 25.4 (0.020 to 1.0 in.) For
depends on the rest of the instrumentation used to read it. The
testing specimens with thicknesses below 0.5 mm, a special
overall performance of the HFT and its readout instrumentation
technique, described in Annex A1, has to be used.
shall be such as to meet the requirements in Section 13.
6.2.8 The lower plate (12) is constructed similarly to the
9. Calibration
upper plate (4), except it is positioned as a mirror image.
9.1 Select the mean temperature and load conditions re-
6.2.9 An insulator plate (16) separates the lower plate (12)
quired. Adjust the upper heater temperature (T ) and lower
u
from the heat sink (17). In case of using circulating fluid in
heater temperature (T ) such that the temperature difference at
l
place of a heater/thermocouple arrangement in the upper or
the required mean temperature is no less than 30 to 35°C and
lower plates, or both, the heat sink may or may not be present.
the specimen DT is not less than 3°C). Adjust the guard heater
6.2.10 The entire stack is surrounded by a cylindrical guard
temperature (T ) such that it is at approximately the average of
g
(18) equipped with a heater (19) and a control thermocouple
T and T .
u l
(20) to maintain it at the mean temperature between the upper
9.2 Select at least two calibration specimens having thermal
and lower plates. A small, generally unfilled, gap separates the
resistance values that bracket the range expected for the test
guard from the stack. For instruments limited to operate in the
specimens at the temperature conditions required.
ambient region, no guard is required. A draft shield is recom-
9.3 Table 1 contains a list of several available materials
mended in place of it.
commonly used for calibration together with corresponding
thermal resistance (R ) values for a given thickness. This
NOTE 2—It is permissible to use thin layers of high-conductivity grease
s
or elastomeric material on the two surfaces of the sample to reduce the
thermal resistance of the interface and promote uniform thermal contact
TABLE 1 Typical Thermal Resistance Values of Specimens of
across the interface area.
Different Materials
NOTE 3—The cross-sectional area of the sample may be any, however,
Approximate Approximate
most commonly circular and rectangular cross sections are used. Mini-
Thermal Thickness, Thermal Resistance,
mum size is dictated by the magnitude of the disturbance caused by
Material
−4 2
Conductivity mm 10 m ·K/W at
thermal sensors in relation to the overall flux distribution. The most
W/(m·K) at 30°C 30°C
common sizes are 25 mm round or square to 50 mm round.
Vespel Polyimide 0.4 20 500
Vespel Polyimide 0.4 10 250
6.2.11 The instrument is to be equipped with suitable means
Vespel Polyimide 0.4 1 25
(21) to measure the thickness of the sample, in situ, in addition
Polyethylene 0.2 1 50
to provisions (22) to limit compression when testing elasto-
Polyethylene 0.2 0.5 25
Polyethylene 0.2 0.1 5
meric or other compressible materials.
Pyroceram 9606 420 50
Pyroceram 9606 410 25
NOTE 4—This requirement is also mandatory for testing materials that
Pyrex 7740 Glass 1 20 200
soften while heated.
Pyrex 7740 Glass 1 10 100
Pyrex 7740 Glass 1 1 10
6.3 Requirements:
304 Stainless Steel 14 20 14
6.3.1 Temperature control of upper and lower plate is to be
304 Stainless Steel 14 10 7
6 0.1°C (0.18°F) or better.
E1530–99
information is provided to assist the user in selecting optimum 10.7.4 Repeat 10.3-10.5 using the test specimen. For com-
specimen thickness for testing a material and in deciding which pressible materials, it is mandatory to measure in situ the
calibration specimens to use. sample thickness under load, and to limit further compression
9.4 The range of thermal conductivity for which this test by suitable mechanical stop.
method is most suitable is such that the optimum thermal 10.8 Thermal Conductivity of Thin Specimens—For speci-
−4 −4 2
resistance range is from 10 3 10 to 400 3 10 m ·K/W. The mens less than approximately 0.5 mm (0.020 in.) in thickness
most commonly used calibration materials are the Pyrex 7740 (and less than 1 mm (0.040 in.) having l greater than 0.5
and Pyroceram 9606 , Vespel (polyimide) and stainless steel all W/(m·K)), a special stacking technique can be used. This is
having a well-established thermal conductivity as a function of described in de
...