ASTM C168-03

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:C168–03
Standard Terminology Relating to
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Thermal Insulation
This standard is issued under the fixed designation C 168; 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.
equipment related measurement errors induced due to measurement
1. Scope
attempts beyond an apparatus range or calibration.
1.1 This standard provides definitions, symbols, units, and
DISCUSSION—Useofthe“apparent”modifierwithsystem Corsystem
abbreviations of terms used in ASTM standards pertaining to
R measurements is not permitted.
thermal insulating materials, and to materials associated with
apparent thermal resistivity, r , n—a thermal resistivity
a
them.
assigned to a material that exhibits thermal transmission by
2. Referenced Documents
several modes of heat transfer resulting in property variation
with specimen thickness, or surface emittance. See resistiv-
2.1 ISO Standard:
ity, thermal.
ISO 7345 Thermal Insulation—Physical Quantities and
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Definitions
DISCUSSION—Seeentirediscussionunder apparent thermal conduc-
tivity.
3. Terminology
batt, n—blanket insulation manufactured to dimensions as
3.1 Definitions:
required by a specific application.
absorptance, n—the ratio of the radiant flux absorbed by a
blackbody, n—the ideal, perfect emitter and absorber of
body to that incident upon it.
thermal radiation. It emits radiant energy at each wavelength
absorption, n—transformation of radiant energy to a different
at the maximum rate possible as a consequence of its
form of energy by interaction with matter.
temperature, and absorbs all incident radiance.
apparent thermal conductivity, l , k , n—a thermal con-
blanket, n—flexible insulation product, supplied rolled or flat.
a a
ductivity assigned to a material that exhibits thermal trans-
blanket insulation, n—a relatively flat and flexible insulation
mission by several modes of heat transfer resulting in
in coherent sheet form furnished in units of substantial area.
property variation with specimen thickness, or surface emit-
blanket insulation, metal mesh, n— blanket insulation cov-
tance. See conductivity, thermal.
ered by flexible metal-mesh facings attached on one or both
sides.
DISCUSSION—Thermal conductivity and resistivity are normally con-
block insulation, n—rigid insulation preformed into rectangu-
sidered to be intrinsic or specific properties of materials and, as such,
lar units.
should be independent of thickness. When nonconductive modes of
heat transfer are present within the specimen (radiation, free convec-
board insulation, n—semirigid insulation preformed into
tion) this may not be the case. To indicate the possible presence of this
rectangular units having a degree of suppleness particularly
phenomena (for example, thickness effect) the modifier “apparent” is
related to their geometrical dimensions.
used, as in apparent thermal conductivity.
calcium silicate, n—insulation composed principally of hy-
DISCUSSION—Test data using the “apparent” modifier must be quoted
drous calcium silicate, and which usually contains reinforc-
only for the conditions of the measurement. Values of thermal conduc-
ing fibers.
tance (material C) and thermal resistance (material R) calculated from
apparent thermal conductivity or resistivity, are valid only for the same cellular elastomeric, n—insulation composed principally of
conditions.
natural or synthetic elastomers, or both, processed to form a
DISCUSSION—Test data labeled with “apparent” shall not include any
flexible, semirigid, or rigid foam which has a predominantly
closed-cell structure.
cellular glass, n—insulation composed of glass processed to
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form a rigid foam having a predominantly closed-cell
This terminology is under the jurisdiction of ASTM Committee C16 on
Thermal Insulation and is the direct responsibility of Subcommittee C16.94 on
structure.
Terminology.
cellular polystyrene, n—insulation composed principally of
Current edition approved April 10, 2003. Published June 2003. Originally
polymerized styrene resin processed to form a rigid foam
approved in 1941. Last previous edition approved in 2002 as C 168 – 02.
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having a predominantly closed-cell structure.
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C168–03
two apparatus/specimen geometries: flat-slab specimens with parallel
cellular polyurethane, n—insulation composed principally of
heat flux lines, or cylindrical specimens with
...