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Hot Disk TPS Absolute measurement of thermal conductivity, thermal diffusivity,and specific heat.
Thermal Conductivity [ W/(m•K)]0.001 0.01 0.1 1.0 10.0 100.0 1000.0 10000.0
Hot Disk TPS
HFM
THW
TLS
-160 to 1000°C
-20 to 70°C
-40 to 100°C
-50 to 400°C
LABORATORY INSTRUMENTS
Thermtest has been advancing the measurement of thermal conductivity, thermal diffusivity, and specific heat for more than a
decade. With more than 1500 satisfied customers, our unique combination of advanced thermal conductivity instrumentation
for the laboratory, portable meters for the field, and accessories, enables us to provide ideal solutions to fit any material testing
application and budget. Our proud commitment to being a leader in thermal conductivity has fueled our success through rigorous
development and key partnerships, creating a lineup of industry leading testing solutions for the laboratory, field, and production-line.
PORTABLE METERS
The Hot Disk TPS is widely used for the accurate measurement of absolute thermal conductivity,
thermal diffusivity, and specific heat of solids, liquids, pastes, and powders. This non-destructive
method has a thermal conductivity testing range of 0.005 to 1800 W/mK and can be used to measure
bulk properties of homogeneous and heterogeneous materials, as well as directional properties
for anisotropic materials. This versatility is greatly appreciated by academic and commercial users
alike, which has led to more than 1000 publications on a wide variety of applications.
Hot Disk Transient Plane Source
SOLIDS
LIQUIDS
PASTES
POWDERS
INTRODUCTION
2
ResistanceRecording
Pure NickelDouble Spiral
Electrical Insulation:Kapton (400°C) orMica (800/1000°C)
Backing Insulation may beadded for single-sided testing
Power Supply
High SensitivityWheatstone Bridge
Multi-channelCommunications
SensorConnections
Hot Disk Transient Plane Source
SENSOR OPTIONS
Featured Hot Disk TPS Capabilities
3
Electrical Insulation:Kapton (400°C) orMica (800/1000°C)
Backing Insulation may beadded for single-sided testing
The TPS sensor is comprised of a flat, double-spiral of Nickel, encapsulated between layers
of dielectric insulation. The sensor is electrically connected to a separated power supply and
electrical resistance sensing circuit. An auto-balancing Wheatstone bridge is used to maximize
electrical resistance sensitivity at the sensor spiral, which is critical for measuring a wide range of
thermal conductivity. During a measurement, a current passes through the spiral and creates an
increase in temperature, which is recorded over time. Heat generated, dissipates into the sample
at a rate dependent on the thermal transport characteristics of the material. A unique feature of
the Hot Disk TPS, is the ability to remove the effects of contact resistance from a measurement
without the use of a contact agent. Contact resistance presents itself as a non-linear region
at the start of the calculated results for the transient measurement. This is easily identified and
removed, manually or automatically, leaving a linear slope free of contact resistance. From this
slope, high accuracy thermal conductivity (W/mK) and thermal diffusivity (mm2/s) is calculated,
without the need of complex calibration. Additional properties including volumetric heat
capacity (MJ/m3K) and thermal effusivity (Ws½/m2K) are automatically calculated and displayed.
• Thermal conductivity, thermal diffusivity, & specific heat
• Solids, liquids, pastes, & powders
• ISO & ASTM Standards
• No calibration
• No contact agent
• Control of penetration depth with variable test times
• Two-sided & single-sided sensors
• Bulk & directional properties
• Proven method with 1000+ publications
k = thermal conductivity P = power a = sensor radius m = slope
Tem
pera
ture
Ris
e
Time Constant
Contact ResistanceTime Constant
Tem
pera
ture
Ris
e
k = P/(π3/2•a•m)
→
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SPECIFICATIONS
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Models TPS 3500 TPS 2500 S
Solids, Liquids, Pastes, and Powders
Thermal Conductivity & Thermal Diffusivity
Bulk or Average
Through-thickness
Through-plane
Two-sided & Single-sided Sensors
Minimum Sample Size (diameter or square) 2 mm 2 mm
Maximum Sample Size 1 Unlimited Unlimited
Thermal Conductivity Range 0.005 to 1800 W/mK 0.005 to 1000+ W/mK
Temperature Range -160 to 1000°C -160 to 1000°C
1 Although there is no maximum sample size, there are limits on depths of heat penetration. This depth of penetration is determined by available test times and thermal diffusivity (mm2/sec) of the material.
TLS Specifications: ASTM D5334, ASTM D5930, & IEEE 442-1981
Thermal Conductivity Range: 0.1 to 5 W/mK
Materials: Soil, Concrete, Rocks, and Plastics
TPS Specifications: ASTM D7984
One Dimensional Thermal Effusivity Range: up to 60,000 Ws½/m2K
Materials: Textiles
TPS EFFUSIVITY MODULE: ALL MODELS
TPS MODELS: STANDARD ISO 22007-2.2
TLS MODULE: ALL MODELSiTPS iTPS
D = Penetration Depthk = Thermal Conductivity a = Thermal Diffusivity t = Time
5
TPS 2200 TPS 1500 TPS 500 / 500S
6 mm 13 mm 13 mm / 6 mm
Unlimited Unlimited Unlimited
0.01 to 500 W/mK 0.01 to 20+ W/mK 0.03 to 100 / 200 W/mK
-160 to 750°C -160 to 750°C -160 to 300°C
THW Specifications: ASTM D7896
Thermal Conductivity Range: 0.01 to 2 W/mK
Materials: Liquids and Pastes
THW MODULE: ALL MODELS
Dilatometer Specifications: ASTM E228
Measures: Coefficient of Thermal Expansion (CTE)
Materials: Solids
DILATOMETER MODULE: ALL MODELSiTPS iTPS
D = Penetration Depthk = Thermal Conductivity a = Thermal Diffusivity t = Time
HOT DISK TPS HIGHLIGHTSVERSATILITY
PENETRATION DEPTH TPS SENSORS iTPS PLUGIN
TPS Automation
ABSOLUTE - QUANTITATIVE NO CONTACT AGENT
Solids, Liquids, Pastes, & Powders
Variable Two -sided & Single -sided Expanded Use
No Calibration Effects of ContactResistance Removed
56
HIGHLIGHTS
iTPS+
A S TM D79 8 4A S TM D5 3 3 4A S TM D593 0A S TM D78 9 6A S TM E 2 2 8
7
VERSATILITY
ABSOLUTE - QUANTITATIVE
The Hot Disk TPS is able to measure solids, liquids, pastes,
and powders for thermal conductivity, thermal diffusivity,
and specific heat. These properties can be measured on a
broad range of samples sizes; samples as small as 2 x 2 mm,
to an unlimited maximum size. For liquids, the sample volume
can be as small as 3 ml. A unique feature of the Hot Disk TPS
- its ability to measure powders of various particle sizes.
Measured results of thermal conductivity, thermal diffusivity, and specific heat are absolute
and quantitative, without the requirement of factory, or user calibrations. The Hot Disk
transient plane source (TPS) technology was developed by Dr. Silas Gustavsson, from his
award-winning research in thermal conductivity measurements, dating back to the 1960’s.
The Hot Disk TPS technology has been widely recognized as one of the most accurate
testing methods commercially available, having undergone multiple independent published
theory investigations. This acceptance has led to more than 1000 systems sold world-
wide and more than 1000+ publications and growing across countless testing applications.
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HIGHLIGHTS
PENETRATION DEPTH
NO CONTACT AGENT
The Hot Disk TPS measures thermal conductivity and thermal diffusivity with different intervals
of test times (0.1 to 1280 sec) and sensor diameters (1 to 60 mm). Control of test times are critical
when using a transient measurement, as it ensures the true thermal conductivity is representative
of the sample dimension and is not just a surface measurement, common to methods using only
short test times. The penetration depth of the heat from the sensor is based on three sample
qualities: dimensions, thermal diffusivity (mm2/s), and test time. As the Hot Disk measures thermal
diffusivity, the results are displayed with representative penetration depth, based on the dimensions
of the sample. Test times can be manually selected, or with the iTPS Plugin, automatically selected.
An important testing capability of the Hot Disk TPS is the ability to remove the
effects of contact resistance, without the need of a contact agent, between the
sensor and sample. The early portion of a test represents contact resistance
and is non-linear, when compared to the remainder of the test, representing
the heat from the sensor as it dissipates into the sample in a linear fashion. The
non-linear portion of the test, representing contact resistance, can be removed
automatically or manually after the measurement is made. As the contact
resistance does not require normalizing with a contact agent, measurements on
materials from insulations to conductive metals are possible, without calibration.
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TWO-SIDED & SINGLE-SIDED
iTPS PLUGIN
Hot Disk TPS sensors can be used in both two-sided and single-sided configurations.
Highly accurate lab testing can be performed by surrounding the flat sensor with a
sample piece, on either side. If two pieces of a sample are not available, the unique
single-sided sensor, first invented by Dr. Silas Gustavsson in 1983*, can be used. There
are two versions of the single-sided sensor available; a standard two-sided sensor
can be configured for single-sided testing by placing an insulation material of known
properties on one side of the sensor, the second option is a permanently configured
spring-loaded single-sided sensor, for convenient testing of large, hard to handle samples.
With the introduction of the iTPS Plugin, full automation of TPS parameters and calculations
is possible. While maintaining the ability to manually select parameters, the iTPS provides
full automation of all aspects of TPS measurement. In addition, the already versatile Hot
Disk TPS is expanded for testing according to multiple international testing standards;
TPS - Thermal Effusivity for Textiles (ASTM D7984), TLS - Thermal Conductivity for Soil,
Concrete, and Polymers (ASTM D5334, ASTM D5930, & IEEE 442-1981), THW - Thermal
Conductivity for Liquids (ASTM D7896), and coefficient of thermal expansion (ASTM E228).
TPS AutomationiTPS
+A S TM D798 4A S TM D53 3 4A S TM D593 0A S TM D789 6A S TM E 2 28
*Gustafsson, Karawacki. July 1983. Transient hot-strip probe for measuring thermal properties ofinsulating solids and liquids. Review of Scientific Instruments, 54(6):744 – 747.
12
10
SAMPLE MEASUREMENTMEASUREMENT
1 min.
2 min.
Power and test time parameters may be selected manually or automatically
with the included iTPS Plugin. Only requiring input of sample dimensions,
the iTPS automatically selects test times to maximize penetration depth
for measurement of thermal conductivity. Advanced software features are
available for automation of multiple tests or control of temperature.
When testing in the laboratory, two sample pieces may be clamped on either
side of the TPS sensor. If two sample pieces are not available, the TPS single-
sided sensor may be used. For compressible materials, a compression stand
may be used to record force applied and thickness of the sample.
SAMPLE SET-UP
TPS SOFTWARE
iTPS
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1 min.
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SAMPLE MEASUREMENT ACCURACY WITH EASE
< 2 min.
As the Hot Disk TPS method is absolute, the results are calculated from
the temperature rise vs. time graph, after a measurement is complete. At
this point, the effects of contact resistance at the early portion of the
measurement can be removed manually or automatically with the iTPS
Plugin. Results can then be exported to Excel or Notepad.
Once start measurement is selected, the Hot Disk TPS will first auto-balance
an internal Wheatstone bridge for maximum sensitivity. A temperature drift
log of 40 seconds is then recorded. Once complete, the test automatically
begins, and the temperature rise with time raw data is displayed.
MEASUREMENT
RESULT CALCULATIONS
12
HOT DISK APPLICATIONSAPPLICATIONS
TWO-SIDED AND SINGLE-SIDED BULK MEASUREMENTSFor standard testing, the Hot Disk measures absolute bulk thermal conductivity, thermal
diffusivity, and auto-calculates volumetric specific heat and thermal effusivity for solids, liquids,
pastes, and powders.
There are two convenient ways to measure thermal properties; lab scale testing, which involves
positioning the two-sided TPS sensor between two pieces of the same sample, and single-sided
testing of one sample piece using the single-sided TPS sensor. In addition to room temperature,
measurements can be made over a wide temperature range. Using the Hot Disk TPS software
and a compatible furnace, the furnace is conveniently controlled through setting an automated
testing schedule that includes the temperatures of interest.
Multiple measurements were made on Pyrex Glass, Pyroceram, and 316 Stainless Steel from 20°C
to 400°C and results show excellent agreement with literature values. The same samples were
measured with both the two-sided and single-sided TPS sensors and results are compared below.
Ther
mal
Con
duct
ivit
y (W
/mK
)
Temperature (˚C)
Pyrex GlassPyroceram316 Stainless Steel
Literature MeasuredPyrex GlassPyroceram316 Stainless Steel
Sample
Two-Sided TPS Single-Sided TPSThermal
Conductivity(W/mK)
ThermalDiffusivity (mm²/s)
VolumetricSpecific Heat
(MJ/m³K)
ThermalEffusivity
(Ws½/m²K)
ThermalConductivity
(W/mK)
ThermalDiffusivity(mm²/s)
VolumetricSpecific Heat
(MJ/m³K)
ThermalEffusivity
(Ws½/m²K)
Pyrex Glass 1.14 0.69 1.71 1416 1.14 0.67 1.71 1396
Pyroceram 3.99 1.92 1.98 2739 3.96 1.93 2.06 2851
316 Stainless Steel 13.72 3.51 3.73 6985 13.46 3.48 3.83 7133
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ANISOTROPIC POLYMER COMPOSITES
Polymer composites, with conductive fillers, are the perfect example of anisotropic materials. These materials experience directional
dependent thermal properties, meaning the in-plane properties differ from through-plane properties. The TPS Anisotropic
Module has the ability to accurately and simultaneously measure the thermal properties of both planes. To create the composites,
synthetic graphite particles were added to a liquid crystal polymer, in varying weight contents. Results indicate a higher in-plane
thermal conductivity, as well as an increasing trend in thermal conductivity, as the weight percentage of graphite increased.
Through-plane results from the TPS testing correlates well with results from the steady-state guarded heat flow meter (ASTM E1536).
Miller, M.G., Keith, J.M., King, J.A., Edwards, B.J., Klinkenberg, N., Schiraldi, D.A. 2006. Measuring the Thermal Conductivities of Anisotropic Synthetic Graphite-Liquid Crystal Polymer Composites. Polymer Composites, 27(4): 388-394.
APPLICATIONS
14
Convection is the dominant force of heat transfer in fluids and must be minimized to
accurately measure thermal conductivity. The TPS method is able to minimize the effects
of convection by lowering the heating power and time settings for each measurement.
With the small volume test cell, only 3 ml of liquid is required. Varying volume fractions
of aluminum nitride particles, 20 nm in diameter, were dispersed into ethanol. Using
the TPS technique, thermal properties were measured at 273.15 K and 297.15 K.
NANOFLUIDS
Hu, P., Shan, W-L., Yu, F., Chen, Z-S. 2008. Thermal Conductivity of AlN-Ethanol Nanofluids. International Journal of Thermophysics, 29: 1968-1973.
Thin sheets are a common geometric shape of conductive materials.
The TPS Slab Module can measure the thermal properties of
such materials, by insulating the lateral surfaces of the sample
with an insulative backing, to minimize heat loss and mimic an
infinite medium in-plane. With the use of Thermtest’s Temperature
Platform, thermal property measurements are possible from 10 to
300˚C. All results showed good agreement with literature values.
HIGH CONDUCTING SLABS
15
SampleHeat
Capacity(J/K)
SpecificHeat
Capacity(J/kgK)
VolumetricHeat
Capacity(MJ/m3K)
Macor 2.53 807 1.97
Stainless Steel 304 2.91 487 3.79
Copper 110 2.49 381 3.38
SPECIFIC HEAT OF MATERIALSThe TPS Specific Heat Module is a convenient method for directly measuring
high accuracy heat capacity of materials. Each cell is fabricated from a
highly conductive material, fastened to a Hot Disk sensor and surrounded
by a thermally insulative backing. With the input of mass and density,
Specific Heat Capacity (J/kgK), and Volumetric Heat Capacity (MJ/m3K), are
also determined. The Specific Heat Capacity (J/kgK) results, show good
agreement with literature values for various materials that were measured,
and the mean results had an excellent reproducibility of less than 0.75%.
Yuan, M. Thermal Conductivity Measurements of Polyamide Powder. Master’s Thesis, The University of Texas at Austin, December 2011. https://repositories.lib.utexas.edu/handle/2152/ETD-UT-2011-12-4476.
Using the TPS method and a standard powder cell, the relationship between
density and thermal conductivity of laser-sintered fresh polyamide 12 powder
was determined. As the contact resistance between sensor and powders of
different particle size is removed, accurate thermal properties can be measured.
3D PRINTER POWDERS
TESTING MODULES
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For measurement of bulk or average thermal conductivity (W/mK), thermal diffusivity
(mm2/s), and volumetric heat capacity (MJ/m3K) of homogeneous and heterogeneous
solids, liquids, pastes, and powders. Standard measurements can be made with TPS
two-sided and TPS single-sided sensors for highest accuracy and maximum flexibility.
Available on: All TPS Models.
STANDARD
Directional (axial and radial) thermal conductivity and thermal diffusivity for anisotropic
materials. This testing module requires the input of volumetric heat capacity; if not
known, it can be easily measured with the TPS specific heat testing module. Anisotropic
measurements may be made with TPS two-sided and TPS single-sided sensors.
Available on: TPS 3500, TPS 2500 S, TPS 2200, TPS 1500
ANISOTROPIC
Thermal conductivity, thermal diffusivity, and volumetric heat capacity of sheets or
slabs. Ideal for thin conductive materials like steel, aluminum, copper, and graphite.
Measurements of samples from 0.04 to 10 mm thick, and as high as 1800 W/mK are possible.
Available on: TPS 3500, TPS 2500 S, TPS 2200, TPS 500 S
SLAB
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Designed for measuring along the length of elongated materials, like rods or core samples.
This module is particularly powerful for testing complex materials, such as heterogeneous
or anisotropic materials, which are difficult to test with standard testing techniques.
This testing can be done with the standard two-sided or single-sided sensor formats.
Available on: TPS 3500, TPS 2500 S, TPS 1500, TPS 500 S
ONE-DIMENSIONAL
Designed for the measurement of thermal conductivity on free standing thin-films
or coatings (> 0.01 mm). The thin-film testing module is most widely used in the
measurement of polymer films, however additional testing of coatings is also possible.
Available on: TPS 3500, TPS 2500 S, TPS 2200
THIN-FILM
In addition to calculated volumetric heat capacity from the measurement of thermal
conductivity and thermal diffusivity, the Hot Disk TPS is able to directly measure, with high
accuracy, specific heat. With various sizes of specific heat cells available (7 to 300 mm),
unique testing of complex structures and heterogeneous materials is possible.
Available on: TPS 3500, TPS 2500 S, TPS 2200, TPS 1500, TPS 500 S
SPECIFIC HEAT
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iTPS EXPANDED
Using the thermal property of effusivity, the human feeling of comfort (coolness or warmth) can be measured for textiles and
automotive interiors. In addition to the initial feeling of comfort, covered by the ASTM, this feeling of comfort can also be measured with
longer touch times, providing design engineers with a full understanding of how effusivity changes with touch time.
TPS – EFFUSIVITY(ASTM D7984)
The transient line source (TLS) method is commonly used for testing the thermal conductivity and thermal resistivity of soils, rocks,
concretes, and plastics. The standard 100 mm probe is ideal for soft, or easy to drill samples, while the shorter 50 mm needle is best
suited for harder to drill, rigid samples like rock and concrete.
TLS - THERMAL CONDUCTIVITY - THERMAL RESISTIVITY(ASTM D5334, ASTM D5930, and IEEE 442-1981)
19
The transient hot wire (THW) method, for thermal conductivity testing of liquids. The THW features unique characteristics to limit the
effects of convection; short test times, thin diameter (0.1 mm) wire, and the wire is held in a vertical orientation, when testing liquids.
With this control of convection, testing of a wide range of viscosities is possible.
THW- THERMAL CONDUCTIVITY(ASTM D7896)
A compact, digital, horizontal, single-sample, benchtop system for measuring dimensional changes of solid materials, such as ceramics,
glass, metals, carbon composites, cements, minerals, and polymers, from RT to 1000°C. The dilatometer records reversible and
irreversible changes in length (expansion and contraction) during heating and cooling.
DILATOMETER – THERMAL EXPANSION(ASTM E228)
ACCESSORIES
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COMPRESSION STAND+ TEMPERATURE
FAN FURNACE
MUFFLE FURNACETUBE FURNACE
TEMPERATURE PLATFORM
• Affordable, compact, rapid testing • -150°C, -50°C or 5 to 300°C
• Size up to: 40 mm diameter x 20 mm • Two channel TPS switch & Gas purge
• Affordable, versatile, expandable• Up to 4 samples
• 300°C, 400°C, & 500°C options• Optional gas purge
• Option 1: 40 x 40 x 13 mm• Option 2: 75 x 75 x 25 mm
• 1000°C in backfilled environment
• Large sample or multiple samples• Size up to: 150 x 150 x 50 mm
• 750°C in backfilled environment
• For compressible materials• Force gauge: 10 to 100 N
• Distance gauge• Room temp or -40 to 200°C
STANDARD TPS SENSORS
TESTING CELLSEXTENDED TPS SENSORS TPS SWITCH
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• One sensor for any sample, 20 mm or larger• Two-sided sensor for accurate lab testing
• Single-sided, spring-loaded sensor for testing of large samples
• Liquid cell: 3 ml• Powder cell
• Paste cell
• Small sensors for samples as small as 2 mm• Large sensors for heterogeneous samples or
large particle powders.
• Automate multi-sensor testing• Channels: x 2, x 4, or x 8
• Can be combined with furnace
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METHODS
Methods Comparison TPS HFM THW TLS Methods Comparison LFA GHP GHFM MTPS
Accuracy ± 5% ± 3% ± 5% ± 5% Accuracy ± 5 to 7% ± 2% ± 5% ± 5 to 15%
Measured Property Thermal Conductivity, Thermal Diffusivity, Specific Heat 1
Thermal Resistance,Thermal Conductivity 1
Thermal Conductivity, Thermal Diffusivity, Specific Heat 1
Thermal Conductivity, Thermal Resistivity 1 Measured Property Thermal Diffusivity, Specific
Heat 1, Thermal Conductivity 1Thermal Resistance,
Thermal Conductivity 1Thermal Resistance,
Thermal Conductivity 1Thermal Effusivity,
Thermal Conductivity 1
Temperature Range -160 to 1000°C -20 to 70°C -50 to 400°C -40 to 100°C Temperature Range -253 to 2800°C -160 to 600°C -20 to 300°C -50 to 200°C
Materials Solids, Liquids, Pastes, &Powders Solids – Insulation Liquids and Pastes Soils, Rocks, & Plastics Materials Solids Solids – Insulation Solids Solids, Liquids, & Paste
Calibration None – Absolute Measurement Single – Offset Single – Offset Multiple – Offset Calibration None – Absolute Measurement None – Absolute Measurement Single – Offset Multiple – Secondary
Contact Resistance Removed After Measurement Removed Through Calibration N/A Contact Paste Contact Resistance Graphite Spray Contact Paste Contact Paste Water & Contact Paste
Penetration Depth Up to 180 mm Entire Sample < 1 mm < 50 mm Penetration Depth Entire Sample Entire Sample Entire Sample 0.1 to 3 mm
Heterogenous Samples < 10 mm scale < 20 mm scale < 1 mm scale < 10 mm scale Heterogenous Samples < 0.1 mm scale < 20 mm scale < 5 mm scale < 0.05 mm scale
Theory ScientificallyReviewed Several Published Papers Several Published Papers Several Published Papers Several Published Papers Theory Scientifically
Reviewed Several Published Papers Several Published Papers Several Published Papers One Published Paper
Specifications sourced from user manuals and available literature.
23
Methods Comparison TPS HFM THW TLS Methods Comparison LFA GHP GHFM MTPS
Accuracy ± 5% ± 3% ± 5% ± 5% Accuracy ± 5 to 7% ± 2% ± 5% ± 5 to 15%
Measured Property Thermal Conductivity, Thermal Diffusivity, Specific Heat 1
Thermal Resistance,Thermal Conductivity 1
Thermal Conductivity, Thermal Diffusivity, Specific Heat 1
Thermal Conductivity, Thermal Resistivity 1 Measured Property Thermal Diffusivity, Specific
Heat 1, Thermal Conductivity 1Thermal Resistance,
Thermal Conductivity 1Thermal Resistance,
Thermal Conductivity 1Thermal Effusivity,
Thermal Conductivity 1
Temperature Range -160 to 1000°C -20 to 70°C -50 to 400°C -40 to 100°C Temperature Range -253 to 2800°C -160 to 600°C -20 to 300°C -50 to 200°C
Materials Solids, Liquids, Pastes, &Powders Solids – Insulation Liquids and Pastes Soils, Rocks, & Plastics Materials Solids Solids – Insulation Solids Solids, Liquids, & Paste
Calibration None – Absolute Measurement Single – Offset Single – Offset Multiple – Offset Calibration None – Absolute Measurement None – Absolute Measurement Single – Offset Multiple – Secondary
Contact Resistance Removed After Measurement Removed Through Calibration N/A Contact Paste Contact Resistance Graphite Spray Contact Paste Contact Paste Water & Contact Paste
Penetration Depth Up to 180 mm Entire Sample < 1 mm < 50 mm Penetration Depth Entire Sample Entire Sample Entire Sample 0.1 to 3 mm
Heterogenous Samples < 10 mm scale < 20 mm scale < 1 mm scale < 10 mm scale Heterogenous Samples < 0.1 mm scale < 20 mm scale < 5 mm scale < 0.05 mm scale
Theory ScientificallyReviewed Several Published Papers Several Published Papers Several Published Papers Several Published Papers Theory Scientifically
Reviewed Several Published Papers Several Published Papers Several Published Papers One Published Paper
1 Italicized property delineates calculated properties.
