ASTM E1530-11(2016)
(Test Method)Standard Test Method for Evaluating the Resistance to Thermal Transmission of Materials by the Guarded Heat Flow Meter Technique
Standard Test Method for Evaluating the Resistance to Thermal Transmission of Materials by the Guarded Heat Flow Meter Technique
SIGNIFICANCE AND USE
5.1 This test method is designed to measure and compare thermal properties of materials under controlled conditions and their ability to maintain required thermal conductance levels.
SCOPE
1.1 This test method covers a steady-state technique for the determination of the resistance to thermal transmission (thermal resistance) of materials of thicknesses less than 25 mm. For homogeneous opaque solid specimens of a representative thickness, thermal conductivity can be determined (see Note 1). This test method is useful for specimens having a thermal resistance in the range from 10 to 400 × 10-4 m 2·K·W-1, which can be obtained from materials of thermal conductivity in the approximate range from 0.1 to 30 W·m-1·K-1 over the approximate temperature range from 150 to 600 K. It can be used outside these ranges with reduced accuracy for thicker specimens and for thermal conductivity values up to 60 W·m-1·K -1.
Note 1: A body is considered homogeneous when the property to be measured is found to be independent of specimen dimensions.
1.2 This test method is similar in concept to Test Method C518, but is modified to accommodate smaller test specimens, having a higher thermal conductance. In addition, significant attention has been paid to ensure that the thermal resistance of contacting surfaces is minimized and reproducible.
1.3 The values stated in SI units are to be regarded as standard. The additional values are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.
1.4 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: E1530 − 11 (Reapproved 2016)
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 E1530; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Related Documents
1.1 This test method covers a steady-state technique for the 2.1 ASTM Standards:
determination of the resistance to thermal transmission (ther- C518Test Method for Steady-State Thermal Transmission
mal resistance) of materials of thicknesses less than 25mm. Properties by Means of the Heat Flow Meter Apparatus
For homogeneous opaque solid specimens of a representative C1045Practice for Calculating Thermal Transmission Prop-
thickness, thermal conductivity can be determined (see Note erties Under Steady-State Conditions
1). This test method is useful for specimens having a thermal E220Test Method for Calibration of Thermocouples By
-4 2 -1
resistance in the range from 10 to 400×10 m ·K·W , which Comparison Techniques
can be obtained from materials of thermal conductivity in the E1142Terminology Relating to Thermophysical Properties
-1 -1
approximate range from 0.1 to 30W·m ·K over the approxi- E1225Test Method for Thermal Conductivity of Solids
mate temperature range from 150 to 600K. It can be used Using the Guarded-Comparative-Longitudinal Heat Flow
outside these ranges with reduced accuracy for thicker speci- Technique
-1 -1
mens and for thermal conductivity values up to 60W·m ·K . F104Classification System for Nonmetallic Gasket Materi-
als
NOTE 1—A body is considered homogeneous when the property to be
F433Practice for Evaluating Thermal Conductivity of Gas-
measured is found to be independent of specimen dimensions.
ket Materials
1.2 This test method is similar in concept to Test Method
C518, but is modified to accommodate smaller test specimens,
3. Terminology
having a higher thermal conductance. In addition, significant
3.1 Definitions of Terms Specific to This Standard:
attention has been paid to ensure that the thermal resistance of
3.1.1 heatfluxtransducer(HFT)—adevicethatproducesan
contacting surfaces is minimized and reproducible.
electrical output that is a function of the heat flux, in a
1.3 The values stated in SI units are to be regarded as
predefined and reproducible manner.
standard. The additional values are mathematical conversions
3.1.2 thermal conductance (C)—the time rate of heat flux
to inch-pound units that are provided for information only and
through a unit area of a body induced by unit temperature
are not considered standard.
difference between the body surfaces.
1.4 This standard does not purport to address all of the
3.1.2.1 average temperature of a surface—the area-
safety concerns, if any, associated with its use. It is the
weighted mean temperature of that surface.
responsibility of the user of this standard to establish appro-
3.1.2.2 average (mean) temperature of a specimen (disc
priate safety, health, and environmental practices and deter-
shaped)—themeanvalueoftheupperandlowerfacetempera-
mine the applicability of regulatory limitations prior to use.
tures.
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.1.3 thermal conductivity (λ)—(of a solid material)—the
ization established in the Decision on Principles for the
time rate of heat flow, under steady conditions, through unit
Development of International Standards, Guides and Recom-
area,perunittemperaturegradientinthedirectionperpendicu-
mendations issued by the World Trade Organization Technical
lar to the area:
Barriers to Trade (TBT) Committee.
3.1.3.1 apparent thermal conductivity—when other modes
of heat transfer through a material are present in addition to
ThistestmethodisunderthejurisdictionofASTMCommitteeE37onThermal
Measurements and is the direct responsibility of Subcommittee E37.05 on Thermo-
physical Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2016. Published September 2016. Originally contact ASTM Customer service at service@astm.org. For Annual Book of ASTM
approved in 1993. Last previous edition approved in 2011 as E1530–11. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1530-11R16. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1530 − 11 (2016)
conduction, the results of the measurements performed in temperatures, to produce a heat flow through the test stack. A
accordance with this test method will represent the apparent or reproducible load is applied to the test stack by pneumatic or
effective thermal conductivity for the material tested. other means, to ensure that there is a reproducible contact
resistance between the specimen and plate surfaces. A guard
3.1.4 thermal resistance (R)—the reciprocal of thermal con-
surrounds the test stack and is maintained at a uniform mean
ductance.
temperature of the two plates, in order to minimize lateral heat
3.2 Symbols:
flow to and from the stack. At steady state, the difference in
-1 -1
temperature between the surfaces contacting the specimen is
λ = thermal conductivity, W·m ·K
-1 -2 -1
measured with temperature sensors embedded in the surfaces,
or Btu·in.·h ·ft ·°F
-2 -1 -1 -2 -1
together with the electrical output of the HFT. This output
C = thermal conductance, W·m ·K or Btu·h ·ft ·°F
2 -1 2 -1
(voltage)isproportionaltotheheatflowthroughthespecimen,
R = thermal resistance, m ·K·W or h·ft ·°F·Btu
the HFT and the interfaces between the specimen and the
∆x = specimen thickness, mm or in
2 2
apparatus. The proportionality is obtained through prior cali-
A = specimen cross-sectional area, m or ft
-1
Q = heat flow, W or Btu·h
bration of the system with specimens of known thermal
φ = heat flux transducer output, mV
resistance measured under the same conditions, such that
-2 -1
N = heatfluxtransducercalibrationconstant,W·m ·mV
contact resistance at the surfaces is made reproducible.
-1 -2 -1
or Btu·h ·ft ·mV
2 -1 2
Nφ = heat flux, W·m or Btu·h ·ft
5. Significance and Use
∆T = temperature difference, °C or °F
5.1 This test method is designed to measure and compare
T = temperature of guard heater, °C or °F
g
T = temperature of upper heater, °C or °F thermalpropertiesofmaterialsundercontrolledconditionsand
u
T = temperature of lower heater, °C or °F their ability to maintain required thermal conductance levels.
l
T = temperature of one surface of the specimen, °C or °F
T = temperatureoftheothersurfaceofthespecimen,°Cor
6. Apparatus
°F
6.1 Aschematicrenderingofatypicalapparatusisshownin
T = mean temperature of the specimen, °C or °F
m
Fig. 1. The relative position of the HFT to the specimen is not
= unknown specimen
s
important(itmaybeonthehotorcoldside)asthetestmethod
= known calibration or reference specimen
r
is based on maintaining axial heat flow with minimal radial
= contacts
o
heat losses or gains. It is also up to the designer whether to
4. Summary of Test Method
choose heat flow upward or downward or horizontally, al-
4.1 A specimen and a heat flux transducer (HFT) are though downward heat flow in a vertical stack is the most
sandwiched between two flat plates controlled at different common one.
FIG. 1 Key Components of a Typical Device
E1530 − 11 (2016)
thermal resistance of the interface and promote uniform thermal contact
6.2 Key Components of a Typical Device (The numbers 1 to
across the interface area.
22 in parentheses refer to Fig. 1):
NOTE 3—The cross-sectional area and the shape of the specimen may
6.2.1 The compressive force for the stack is to be provided
be any, however, most commonly circular and rectangular cross sections
by either a regulated pneumatic or hydraulic cylinder (1), dead
are used. Minimum size is dictated by the magnitude of the disturbance
caused by thermal sensors in relation to the overall flux distribution. The
weights or a spring loaded mechanism. In either case, means
most common sizes are 25mm round or square to 50 mm round.
must be provided to ensure that the loading can be varied and
set to certain values reproducibly. 6.2.11 The instrument is preferably equipped with suitable
means(21)tomeasurethethicknessofthespecimen,insitu,in
6.2.2 The loading force must be transmitted to the stack
addition to provisions (22) to limit compression when testing
through a gimball joint (2) that allows up to 5° swivel in the
elastomeric or other compressible materials.
plane perpendicular to the axis of the stack.
6.2.3 Suitable insulator plate (3) separates the gimball joint
NOTE 4—This requirement is also mandatory for testing materials that
from the top plate (4). soften while heated.
6.2.4 The top plate (assumed to be the hot plate for the
6.3 Requirements:
purposes of this description) is equipped with a heater (5) and
6.3.1 Temperature control of upper and lower plate is to be
control thermocouple (6) adjacent to the heater, to maintain a
60.1°C (0.18°F) or better.
certain desired temperature. (Other means of producing and
6.3.2 Reproducible load of 0.28MPa (40psi) has been
maintaining temperature may also be used as long as the
found to be satisfactory for solid specimens. Minimum load
requirements in 6.3 are met.) The construction of the top plate
shall not be below 0.07MPa (10psi).
is such as to ensure uniform heat distribution across its face
6.3.3 Temperature sensors are usually fine gage or small-
contacting the specimen (8). Attached to this face (or embed-
diameter sheath thermocouples, however, ultraminiature resis-
ded in close proximity to it) in a fashion that does not interfere
tance thermometers and linear thermistors may also be used.
with the specimen/plate interface, is a temperature sensor (7)
6.3.4 Operating range of a device using a mean temperature
(typically a thermocouple, resistance thermometer, or a therm-
guard shall be limited to from −100 to 300°C, when using
istor) that defines the temperature of the interface on the plate
thermocouples as temperature sensors, and from −180 to
side.
300°C when platinum resistance thermometers are used.
6.2.5 Thespecimen(8)isindirectcontactwiththetopplate Thermistors are normally present on more restricted allowable
temperature range of use.
on one side and an intermediate plate (9) on the other side.
6.2.6 The intermediate plate (9) is an optional item. Its
7. Sampling and Conditioning
purpose is to provide a highly conductive environment to the
7.1 Cut representative test specimens from larger pieces of
second temperature sensor (10), to obtain an average tempera-
ture of the surface. If the temperature sensor (10) is embedded the sample material or body.
into the face of the HFT, or other means are provided to define
7.2 Condition the cut specimens in accordance with the
the temperature of the surface facing the specimen, the use of
requirements of the appropriate material specifications, if any.
the intermediate plate is not mandatory.
6.2.7 The heat flux transducer (HFT) is a device that will 8. Test Specimen
generate an electrical signal in proportion to the heat flux
8.1 The specimen to be tested should be representative for
across it. The level of output required (sensitivity) greatly
the sample material. The recommended specimen configura-
depends on the rest of the instrumentation used to read it. The
tionisa50.8 60.25mm(2 60.010in.)diameterdisk,having
overallperformanceoftheHFTanditsreadoutinstrumentation
smooth flat and parallel faces, 60.025mm (60.001in.), such
shall be such as to meet the requirements in Section 13.
that a uniform thickness within 60.025mm (60.001in.) is
6.2.8 The lower plate (12) is constructed similarly to the
attainedintherangefrom0.5to25.4mm(0.020to1.0in.)For
upper plate (4), except it is positioned as a mirror image.
testing specimens with thicknesses below 0.5mm, a special
6.2.9 An insulator plate (16) separates the lower plate (12)
technique, described in Annex A1, has to be used. Other
from the heat sink (17). In case of using circulating fluid in frequentlyfavoredsizesare25.4mm(1.00in.)roundorsquare
place of a heater/thermocouple arrangement in the upper or cross section.
lower plates, or both, the heat sink may or may not be present.
9. Calibration
6.2.10 The entire stack is surrounded by a guard whose
cross section is not too much different from the stack’s (18)
9.1 Select the mean temperature and load conditions re-
equipped with a heater or cooling coils (19), or both, and a quired. Adjust the upper heater temperature (T ) and lower
u
control thermocouple, resistance thermometer or thermistor
heater temperature (T) such that the temperature difference at
l
(20) to maintain it at the mean temperature between the upper the required mean temperature is no less than 30 to 35°C and
and lower plates.Asmall, generally unfilled, gap separates the
the specimen ∆T is not less than 3°C.Adjust the guard heater
guard from the stack. For instruments limited to operate in the
temperature (T ) such that it is at approximately the average of
g
ambient region, no guard is required but a draft shield is
T and T.
u l
recommended in place of it.
9.2 Select at least three calibration specimens having ther-
mal resistance values that bracket the range expected for the
NOTE2—Itispermissibletousethinlayersofhigh-conductivitygrease
or elastomeric material on the two surfaces of the specimen to reduce the test specimens at the temperature conditions required.
E1530 − 11 (2016)
TABLE 2 Thermal Conductivity Values of Selected Reference
9.3 Table 1 contains a list of several available materials
Materials
commonly used for calibration together with corresponding
-1 -1
Thermal Conductivity (W·m ·K )
thermal resistance (R ) values for a given thickness. This
s
Temperature (°C)
A B C
Vespel Pyrex 7740 Pyroceram 9696
information is provided to assist the user in selecting optimum
–50 { 1.010 {
specimenthicknessfortestingamaterialandindecidingwhich
0 { 1.104 {
calibration specimens to use.
25 0.377 1.177 4.03
100 0.391 1.236 3.65
9.4 The range of thermal conductivity for which this test
200 0.413 1.330 3.40
D
method is most suitable is such that the optimum thermal
300 0.436 1.447 3.24
-4 -4 2 -1
resistance range is from 10×10 to 400×10 m ·K·W . 400 {{ 3.14
500 {{ 3.05
The most commonly used calibration materials are the Pyrex
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1530 − 11 E1530 − 11 (Reapproved 2016)
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 E1530; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers a steady-state technique for the determination of the resistance to thermal transmission (thermal
resistance) of materials of thicknesses less than 25 mm. For homogeneous opaque solid specimens of a representative thickness,
thermal conductivity can be determined (see Note 1). This test method is useful for specimens having a thermal resistance in the
-4 2 -1
range from 10 to 400 × 10 m ·K·W , which can be obtained from materials of thermal conductivity in the approximate range
-1 -1
from 0.1 to 30 W·m ·K over the approximate temperature range from 150 to 600 K. It can be used outside these ranges with
-1 -1
reduced accuracy for thicker specimens and for thermal conductivity values up to 60 W·m ·K .
NOTE 1—A body is considered homogeneous when the property to be measured is found to be independent of specimen dimensions.
1.2 This test method is similar in concept to Test Method C518, but is modified to accommodate smaller test specimens, having
a higher thermal conductance. In addition, significant attention has been paid to ensure that the thermal resistance of contacting
surfaces is minimized and reproducible.
1.3 The values stated in SI units are to be regarded as standard. The additional values are mathematical conversions to
inch-pound units that are provided for information only and are not considered standard.
1.4 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.
2. Related Documents
2.1 ASTM Standards:
C518 Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus
C1045 Practice for Calculating Thermal Transmission Properties Under Steady-State Conditions
E220 Test Method for Calibration of Thermocouples By Comparison Techniques
E1142 Terminology Relating to Thermophysical Properties
E1225 Test Method for Thermal Conductivity of Solids Using the Guarded-Comparative-Longitudinal Heat Flow Technique
F104 Classification System for Nonmetallic Gasket Materials
F433 Practice for Evaluating Thermal Conductivity of Gasket Materials
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 heat flux transducer (HFT)—a device that produces an electrical output that is a function of the heat flux, in a predefined
and reproducible manner.
3.1.2 thermal conductance (C)—the time rate of heat flux through a unit area of a body induced by unit temperature difference
between the body surfaces.
3.1.2.1 average temperature of a surface—the area-weighted mean temperature of that surface.
3.1.2.2 average (mean) temperature of a specimen (disc shaped)—the mean value of the upper and lower face temperatures.
This test method is under the jurisdiction of ASTM Committee E37 on Thermal Measurements and is the direct responsibility of Subcommittee E37.05 on
Thermophysical Properties.
Current edition approved Aug. 15, 2011Sept. 1, 2016. Published September 2011September 2016. Originally approved in 1993. Last previous edition approved in
20062011 as E1530 – 06.E1530 – 11. DOI: 10.1520/E1530-11.10.1520/E1530-11R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1530 − 11 (2016)
3.1.3 thermal conductivity (λ)—(of a solid material)—the time rate of heat flow, under steady conditions, through unit area, per
unit temperature gradient in the direction perpendicular to the area:
3.1.3.1 apparent thermal conductivity—when other modes of heat transfer through a material are present in addition to
conduction, the results of the measurements performed in accordance with this test method will represent the apparent or effective
thermal conductivity for the material tested.
3.1.4 thermal resistance (R)—the reciprocal of thermal conductance.
E1530 − 11 (2016)
3.2 Symbols:
-1 -1
3.2.1 λ—thermal conductivity, W·m ·K
-1 -2 -1
or Btu·in.·h ·ft ·°F .
-1 -1
λ = thermal conductivity, W·m ·K
-1 -2 -1
or Btu·in.·h ·ft ·°F
-2 -1 -1 -2 -1
C = thermal conductance, W·m ·K or Btu·h ·ft ·°F
2 -1 2 -1
R = thermal resistance, m ·K·W or h·ft ·°F·Btu
Δx = specimen thickness, mm or in
2 2
A = specimen cross-sectional area, m or ft
-1
Q = heat flow, W or Btu·h
φ = heat flux transducer output, mV
- 2 -1 -1 -2 -1
N = heat flux transducer calibration constant, W·m ·mV or Btu·h ·ft ·mV
2 -1 2
Nφ = heat flux, W·m or Btu·h ·ft
ΔT = temperature difference, °C or °F
T = temperature of guard heater, °C or °F
g
T = temperature of upper heater, °C or °F
u
T = temperature of lower heater, °C or °F
l
T = temperature of one surface of the specimen, °C or °F
T = temperature of the other surface of the specimen, °C or °F
T = mean temperature of the specimen, °C or °F
m
= unknown specimen
s
= known calibration or reference specimen
r
= contacts
o
-2 -1
3.2.2 C—thermal conductance, W·m ·K
-1 -2 -1
or Btu·h ·ft ·°F .
2 -1 2 -1
3.2.3 R—thermal resistance, m ·K·W or h·ft ·°F·Btu .
3.2.4 Δx—specimen thickness, mm or in.
2 2
3.2.5 A—specimen cross-sectional area, m or ft .
-1
3.2.6 Q—heat flow, W or Btu·h .
3.2.7 φ—heat flux transducer output, mV.
3.2.8 N—heat flux transducer calibration constant,
- 2 -1 -1 -2 -1
W·m ·mV or Btu·h ·ft ·mV .
2 -1 2
3.2.9 Nφ—heat flux, W·m or Btu·h ·ft .
3.2.10 ΔT—temperature difference, °C or °F.
3.2.11 T —temperature of guard heater, °C or °F.
g
3.2.12 T —temperature of upper heater, °C or °F.
u
3.2.13 T —temperature of lower heater, °C or °F.
l
3.2.14 T —temperature of one surface of the specimen, °C or °F.
3.2.15 T —temperature of the other surface of the specimen, °C or °F.
3.2.16 T —mean temperature of the specimen, °C or °F.
m
3.2.17 —unknown specimen.
s
3.2.18 —known calibration or reference specimen.
r
3.2.19 —contacts.
o
4. Summary of Test Method
4.1 A specimen and a heat flux transducer (HFT) are sandwiched between two flat plates controlled at different temperatures,
to produce a heat flow through the test stack. A reproducible load is applied to the test stack by pneumatic or other means, to ensure
that there is a reproducible contact resistance between the specimen and plate surfaces. A guard surrounds the test stack and is
maintained at a uniform mean temperature of the two plates, in order to minimize lateral heat flow to and from the stack. At steady
state, the difference in temperature between the surfaces contacting the specimen is measured with temperature sensors embedded
in the surfaces, together with the electrical output of the HFT. This output (voltage) is proportional to the heat flow through the
specimen, the HFT and the interfaces between the specimen and the apparatus. The proportionality is obtained through prior
calibration of the system with specimens of known thermal resistance measured under the same conditions, such that contact
resistance at the surfaces is made reproducible.
E1530 − 11 (2016)
5. Significance and Use
5.1 This test method is designed to measure and compare thermal properties of materials under controlled conditions and their
ability to maintain required thermal conductance levels.
6. Apparatus
6.1 A schematic rendering of a typical apparatus is shown in Fig. 1. The relative position of the HFT to the specimen is not
important (it may be on the hot or cold side) as the test method is based on maintaining axial heat flow with minimal radial heat
losses or gains. It is also up to the designer whether to choose heat flow upward or downward or horizontally, although downward
heat flow in a vertical stack is the most common one.
6.2 Key Components of a Typical Device (The numbers 1 to 22 in parentheses refer to Fig. 1):
6.2.1 The compressive force for the stack is to be provided by either a regulated pneumatic or hydraulic cylinder (1), dead
weights or a spring loaded mechanism. In either case, means must be provided to ensure that the loading can be varied and set
to certain values reproducibly.
6.2.2 The loading force must be transmitted to the stack through a gimball joint (2) that allows up to 5° swivel in the plane
perpendicular to the axis of the stack.
6.2.3 Suitable insulator plate (3) separates the gimball joint from the top plate (4).
6.2.4 The top plate (assumed to be the hot plate for the purposes of this description) is equipped with a heater (5) and control
thermocouple (6) adjacent to the heater, to maintain a certain desired temperature. (Other means of producing and maintaining
temperature may also be used as long as the requirements in 6.3 are met.) The construction of the top plate is such as to ensure
uniform heat distribution across its face contacting the specimen (8). Attached to this face (or embedded in close proximity to it)
in a fashion that does not interfere with the specimen/plate interface, is a temperature sensor (7) (typically a thermocouple,
resistance thermometer, or a thermistor) that defines the temperature of the interface on the plate side.
6.2.5 The specimen (8) is in direct contact with the top plate on one side and an intermediate plate (9) on the other side.
6.2.6 The intermediate plate (9) is an optional item. Its purpose is to provide a highly conductive environment to the second
temperature sensor (10), to obtain an average temperature of the surface. If the temperature sensor (10) is embedded into the face
of the HFT, or other means are provided to define the temperature of the surface facing the specimen, the use of the intermediate
plate is not mandatory.
6.2.7 The heat flux transducer (HFT) is a device that will generate an electrical signal in proportion to the heat flux across it.
The level of output required (sensitivity) greatly depends on the rest of the instrumentation used to read it. The overall performance
of the HFT and its readout instrumentation shall be such as to meet the requirements in Section 13.
6.2.8 The lower plate (12) is constructed similarly to the upper plate (4), except it is positioned as a mirror image.
FIG. 1 Key Components of a Typical Device
E1530 − 11 (2016)
6.2.9 An insulator plate (16) separates the lower plate (12) from the heat sink (17). In case of using circulating fluid in place
of a heater/thermocouple arrangement in the upper or lower plates, or both, the heat sink may or may not be present.
6.2.10 The entire stack is surrounded by a guard whose cross section is not too much different from the stack’s (18) equipped
with a heater or cooling coils (19), or both, and a control thermocouple, resistance thermometer or thermistor (20) to maintain it
at the mean temperature between the upper and lower plates. A small, generally unfilled, gap separates the guard from the stack.
For instruments limited to operate in the ambient region, no guard is required but a draft shield is recommended in place of it.
NOTE 2—It is permissible to use thin layers of high-conductivity grease or elastomeric material on the two surfaces of the specimen to reduce the
thermal resistance of the interface and promote uniform thermal contact across the interface area.
NOTE 3—The cross-sectional area and the shape of the specimen may be any, however, most commonly circular and rectangular cross sections are used.
Minimum size is dictated by the magnitude of the disturbance caused by thermal sensors in relation to the overall flux distribution. The most common
sizes are 25 mm round or square to 50 mm round.
6.2.11 The instrument is preferably equipped with suitable means (21) to measure the thickness of the specimen, in situ, in
addition to provisions (22) to limit compression when testing elastomeric or other compressible materials.
NOTE 4—This requirement is also mandatory for testing materials that soften while heated.
6.3 Requirements:
6.3.1 Temperature control of upper and lower plate is to be 60.1 °C (0.18 °F)60.1°C (0.18°F) or better.
6.3.2 Reproducible load of 0.28 MPa (40 psi) has been found to be satisfactory for solid specimens. Minimum load shall not
be below 0.07 MPa (10 psi).
6.3.3 Temperature sensors are usually fine gage or small-diameter sheath thermocouples, however, ultraminiature resistance
thermometers and linear thermistors may also be used.
6.3.4 Operating range of a device using a mean temperature guard shall be limited to from −100 to 300 °C,300°C, when using
thermocouples as temperature sensors, and from −180 to 300 °C300°C when platinum resistance thermometers are used.
Thermistors are normally present on more restricted allowable temperature range of use.
7. Sampling and Conditioning
7.1 Cut representative test specimens from larger pieces of the sample material or body.
7.2 Condition the cut specimens in accordance with the requirements of the appropriate material specifications, if any.
8. Test Specimen
8.1 The specimen to be tested should be representative for the sample material. The recommended specimen configuration is
a 50.8 6 0.25 mm (2 6 0.010 in.) diameter disk, having smooth flat and parallel faces, 60.025 mm (60.001 in.), such that a
uniform thickness within 60.025 mm (60.001 in.) is attained in the range from 0.5 to 25.4 mm (0.020 to 1.0 in.) For testing
specimens with thicknesses below 0.5 mm, a special technique, described in Annex A1, has to be used. Other frequently favored
sizes are 25.4 mm (1.00 in.) round or square cross section.
9. Calibration
9.1 Select the mean temperature and load conditions required. Adjust the upper heater temperature (T ) and lower heater
u
temperature (T ) such that the temp
...
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