ASTM E2584-07
(Practice)Standard Practice for Thermal Conductivity of Materials Using a Thermal Capacitance (Slug) Calorimeter
Standard Practice for Thermal Conductivity of Materials Using a Thermal Capacitance (Slug) Calorimeter
SCOPE
1.1 This practice describes a technique for the determination of the apparent thermal conductivity, a, of materials. It is for solid materials with apparent thermal conductivities in the approximate range 0.02 a 2 W/(mK) over the approximate temperature range between 300 K and 1100 K.Note 1
While the practice should also be applicable to determining the thermal conductivity of non-reactive materials, it has been found specifically useful in testing fire resistive materials that are both reactive and undergo significant dimensional changes during a high temperature exposure.
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: E2584 – 07
Standard Practice for
Thermal Conductivity of Materials Using a Thermal
Capacitance (Slug) Calorimeter
This standard is issued under the fixed designation E2584; 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 3. Terminology
1.1 Thispracticedescribesatechniqueforthedetermination 3.1 Definitions:
of the apparent thermal conductivity, l , of materials. It is for 3.1.1 thermal conductivity, l—the time rate of heat flow,
a
solid materials with apparent thermal conductivities in the understeadyconditions,throughunitarea,perunittemperature
approximate range 0.02 < l < 2 W/(m·K) over the approxi- gradient in the direction perpendicular to the area.
a
mate temperature range between 300 K and 1100 K. 3.1.2 apparent thermal conductivity, l —when other modes
a
of heat transfer (and mass transfer) through a material are
NOTE 1—While the practice should also be applicable to determining
present in addition to thermal conduction, the results of the
the thermal conductivity of non-reactive materials, it has been found
measurements performed according to this practice will repre-
specifically useful in testing fire resistive materials that are both reactive
sent the apparent or effective thermal conductivity for the
and undergo significant dimensional changes during a high temperature
exposure.
material tested.
3.2 Symbols:
1.2 This standard does not purport to address all of the
A = specimen area normal to heat flux direction, m
safety concerns, if any, associated with its use. It is the
C = specific heat capacity, J/(kg·K)
p
responsibility of the user of this standard to establish appro-
F = heating or cooling rate, (K/s)
priate safety and health practices and determine the applica-
L = thickness of a specimen (slab) in heat transfer direc-
bility of regulatory limitations prior to use.
tion, m
2. Referenced Documents
M = mass, kg
Q = heat flow, W
2.1 ASTM Standards:
T = absolute temperature, K
C1113 Test Method for Thermal Conductivity of Refracto-
SSS
T = mean temperature of the stainless steel slug, K
ries by HotWire (Platinum ResistanceThermometerTech-
inner
SPEC
T = mean temperature of outer (exposed) specimen
nique) outer
surfaces, K
D2214 Test Method for Estimating the Thermal Conductiv-
SPEC
T = mean temperature of specimen, K
ity of Leather with the Cenco-Fitch Apparatus mean
DT = temperature difference across the specimen, given by
E220 Test Method for Calibration of Thermocouples By
SPEC SSS
(T – T ), K,
Comparison Techniques outer inner
l = thermal conductivity, W/(m·K)
E230 Specification and Temperature-Electromotive Force
l = apparent thermal conductivity, W/(m·K)
(EMF) Tables for Standardized Thermocouples a
SPEC 3
r = bulk density of specimen being tested, kg/m
E457 Test Method for Measuring Heat-Transfer Rate Using
3.3 Subscripts/Superscripts:
a Thermal Capacitance (Slug) Calorimeter
SPEC = material specimen being evaluated
E691 Practice for Conducting an Interlaboratory Study to
SSS = stainless steel slug (thermal capacitance transducer)
Determine the Precision of a Test Method
4. Summary of Practice
This practice is under the jurisdiction of ASTM Committee E37 on Thermal
4.1 Principle of Operation—In principle, a slug of ther-
Measurements and is the direct responsibility of Subcommittee E37.05 on Thermo-
mally conductive metal, capable of withstanding elevated
physical Properties.
temperatures, is surrounded with another material of a uniform
Current edition approved Sept. 1, 2007. Published November 2007. DOI:
10.1520/E2584-07.
thickness (the specimen) whose thermal conductivity is sub-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
stantially lower than that of the slug.When the outer surface of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
this assembly is exposed to a temperature above that of the
Standards volume information, refer to the standard’s Document Summary page on
slug, heat will pass through the outer layer, causing a tempera-
the ASTM website.
Withdrawn. The last approved version of this historical standard is referenced
ture rise in the slug itself. The temperature rise of the slug is
on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2584 – 07
controlled by the amount and rate of heat conducted to its surfaces of the specimens versus time are measured during the
surface (flux), its mass, and its specific heat capacity. With the course of multiple heating and cooling cycles. Under steady-
knowledge of these properties, the rate of temperature rise of state (constant rate) heating or cooling conditions, the apparent
theslugisindirectproportiontotheheatfluxenteringit.Thus, thermal conductivity is derived from the measured temperature
under these conditions, the slug becomes a flux-gauging gradients across the two specimens, the measured rate of
device. From this measured flux, along with the measured temperature increase/decrease of the steel slug, and the known
thermalgradientacrosstheouter(specimen)layer,theapparent masses and specific heat capacities of the specimens and the
thermal conductivity of the specimen can be calculated. When stainless steel slug. In principle, the test apparatus is similar to
the heat source is removed, during natural cooling, the direc- theCenco-Fitchapparatus(1) thatisemployedinTestMethod
tion of the heat flow will be reversed. Still, from the measured D2214 for determining the thermal conductivity of leather.
flux and thermal gradient, the apparent thermal conductivity Measuring the heat transfer through a material by using a
can be calculated. thermalcapacitancetransducerissimilartotheapproachthatis
employed for measuring heat-transfer rates in Test Method
4.2 Boundary Conditions—The ideal model described
above is based on heat flow toward the slug, perpendicularly to E457.
4.4.2 Single Specimen (One-Sided)—Similarlytotheabove,
the specimen, and always through the specimen. Deviating
one unknown specimen is placed on one side of the slug and
from ideality can be due to:
another known specimen (buffer) of extremely high thermal
4.2.1 Thickness non-uniformity of the outer layer.
resistance is placed on the other side. In this instance, the outer
4.2.2 Inhomogeneity (chemical or microstructural) of the
surface of the buffer may be heated at the same time as the
outer layer.
other side, just like in case of a twin specimen, or may be left
4.2.3 Parasitic paths through cracks, gaps or other mechani-
unheated if it can be established that heat losses from the slug
cally induced paths.
through this face are negligible.
4.2.4 Parasitic paths through wires, sheaths (thermo-
couples), etc. that are unavoidable parts of a practical embodi-
5. Significance and Use
ment.
5.1 This practice is useful for testing materials in general,
4.2.5 Delamination of the specimen from the slug’s surface
including composites and layered types.
(gap formation).
5.2 The practice is especially useful for materials which
NOTE 2—The user of this method should be very aware of the fact that
undergo significant reactions and/or local dimensional changes
the contact resistance between the specimen(s) and the slug may not
during exposure to elevated temperatures and thus are difficult
alwaysbeneglected,andinsomecasesmaybeevensignificant,becoming
to evaluate using existing standard test methods such as Test
probably the most important source of uncertainty in the measurement.
Method C1113.
For low-density porous materials, however, it was found that, generally,
5.3 Performing the test over multiple heating/cooling cycles
the contact resistance between the specimen(s) and the slug may be
neglected. allows an assessment of the influence of reactions, phase
changes, and mass transfer of reactions gases (e.g., steam) on
4.3 Configurations—This method lends itself to many pos-
the thermal performance.
sible geometrical configurations, a few of which are listed
NOTE 3—This method has been found to be especially applicable to
below:
testing fire resistive materials.
4.3.1 For pipe (tubular) insulations, a cylindrical slug is to
be used. End faces are to be blocked with insulation.
6. Apparatus
4.3.2 For flat plate stock (insulating boards, bulk materials,
6.1 Thermal Capacitance (Slug) Calorimeter:
etc.), a rectangular shaped slug is considered most practical,
6.1.1 The steel slug shall be manufactured from AISI 304
with the specimen material covering:
stainless steel or any other well characterized material of
4.3.2.1 Both large faces of the slab, with the edges heavily
proper temperature service. Dimensions of the steel slug and
insulated.
the holes to be drilled for temperature sensor insertion are
4.3.2.2 One large face of the slab, with the other face and
provided in Fig. 1. These dimensions and configuration are
the edges heavily insulated.
used for expediency in further discussion, without the intent of
4.4 Operation—For simplicity, only the rectangular em-
posing restrictions on other sizes or configurations, or hinder-
bodiment is described below:
ing the adaptation of other engineering solutions.
4.4.1 Twin Specimens (Double-Sided)—A sandwich test
6.1.2 Two high temperature metal retaining plates, nomi-
specimen is prepared consisting of twin specimens of the
nally of size 200 by 200 mm, shall be employed to hold the
material, of known mass and known and nominally identical
twin specimens, steel slug, and surrounding guard insulation in
thickness, between which is sandwiched a stainless steel
place and under a slight compression.
thermal capacitance transducer (slug) of known mass. The
6.1.3 The steel slug and twin specimens shall be surrounded
entire sandwich is placed between two (high temperature)
on all sides by an appropriate high temperature insulation,
metal retaining plates, and the bolts holding the configuration
nominally of 25 mm thickness. Three holes shall be drilled
together are tightened with a torque not to exceed 1 kg·m, to
maintain a slight compressive load on the specimen. The
assembled specimen is placed in a temperature-controlled
The boldface numbers in parentheses refer to the list of references at the end of
environmentandthetemperaturesofthesteelslugandexposed this standard.
E2584 – 07
FIG. 1 Schematic of AISI 304 Stainless Steel Slug Calorimeter
through the section of insulation that covers the top of the slug environment ranges in temperature between room temperature
in direct line with the corresponding milled holes in the steel and1000°Cduringthecourseofasingleheating/coolingcycle.
slug to allow for insertion of the temperature sensors. 6.3.2 One example would be a temperature-controlled fur-
6.2 Insulation Materials: nacewithanelectroniccontrolsystemthatallowstheprogram-
6.2.1 A large variety of materials exists for providing the ming of one or more temperature ramps. For example, the
guard insulation that surrounds the stainless steel slug and following temperature setpoints (versus time) have been suc-
specimens.Severalfactorsmustbeconsideredduringselection cessfullyemployedinthepast:538°Cafter45min,704°Cafter
of the most appropriate insulation. The insulation must be 70 min, 843°C after 90 min, 927°C after 105 min, and 1010°C
stable over the anticipated temperature range, have a very low after 2 h.
l, and be easy to handle, cut, and insert holes. In addition, the 6.4 Temperature Sensors:
insulation should not contaminate system components, it must 6.4.1 There shall be a minimum of three temperature
have a low toxicity, and it should not conduct electricity. In sensors to be inserted into the pre- drilled holes in the stainless
general, microporous insulation boards are employed. Typi- steel slug. The multiple sensors are useful to indicate the
cally, these materials exhibit a room temperature thermal validity of one-dimensional heat transfer through the speci-
conductivity as low as 0.02 W/(m·K) and a thermal conduc- men(s) to the steel slug. Temperature sensors may also be
tivity of less than 0.04 W/(m·K) at 1073 K. These values are mounted in milled grooves on the exterior surface of the
much lower than those of typical materials that can be tested specimens, one sensor per specimen.When this is not possible,
using this method. the exposed face of the specimen may be assumed to have a
6.3 Temperature-Controlled Environment: temperature equal to the measured temperature of the
6.3.1 The temperature controlled environment shall consist temperature-controlled environment.
of an enclosed volume in which the temperature can be 6.4.2 For the purposes of this test, it is reasonable to
controlled during heating and monitored during (natural) postulate that the surface temperature of the slug is identical to
cooling. The heating units shall be capable of supplying its mean temperature. When comparatively high thermal con-
sufficient energy to achieve the temperatures required for the ductivity specimens are used, it is practical to embed a
evaluation of the materials under test. Typically, the heated temperature sensor near to or on the slug’s surface.
E2584 – 07
6.4.3 Anysensorpossessingadequateaccuracymaybeused knife or hacksaw blade for fibrous and soft materials, or by
for temperature measurement. Type K or Type N thermo- using a file or an electric sander for “harder” materials. The
couples are normally employed. Their small size and ease of thickness of the specimen shall be determined by measurement
manufacturing are distinct advantages. The sensors simply usingadigitalthicknessgauge(digitalcalipers).Aminimumof
must fit into the holes present in the thermal capacitance eight measurements (two from each of the four sides of the
calorimeter, where they can be easily inserted during the specimen slab) shall be performed and the mean and standard
assembly of the configuration within the temperature- deviation shall be reported. If the standard deviation is greater
controlled environment. than 1 mm, the specimen shall be either discarded or replaned
6.4.4 When thermocouples are employed, a constant tem- in an attempt to achieve a more uniform thickness.
perature reference shall always be provided for all cold 8.1.2 As an alternative to testing bulk specimens, thinner
junctions. This reference can be an ice-cold slurry, a constant specimens may be applied to pre-weighed AISI Type 304
temperature zone box, or an integrated co
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