ASTM C168-01

Designation: C 168 – 01
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.
DISCUSSION—Useofthe“apparent”modifierwithsystem Corsystem
1. Scope
R measurements is not permitted.
1.1 This standard provides definitions, symbols, units, and
abbreviations of terms used in ASTM standards pertaining to apparent thermal resistivity, r , n—a thermal resistivity
a
thermal insulating materials, and to materials associated with assigned to a material that exhibits thermal transmission by
them. several modes of heat transfer resulting in property variation
with specimen thickness, or surface emittance. See resistiv-
2. Referenced Documents
ity, thermal.
2.1 ISO Standard:
DISCUSSION—Seeentirediscussionunder apparent thermal conduc-
ISO 7345 Thermal Insulation—Physical Quantities and
tivity.
2
Definitions
blackbody, n—the ideal, perfect emitter and absorber of
3. Terminology
thermal radiation. It emits radiant energy at each wavelength
at the maximum rate possible as a consequence of its
3.1 Definitions:
temperature, and absorbs all incident radiance.
absorptance, n—the ratio of the radiant flux absorbed by a
blanket insulation, n—a relatively flat and flexible insulation
body to that incident upon it.
in coherent sheet form furnished in units of substantial area.
absorption, n—transformation of radiant energy to a different
blanket insulation, metal mesh, n— blanket insulation cov-
form of energy by interaction with matter.
ered by flexible metal-mesh facings attached on one or both
apparent thermal conductivity, l , k , n—a thermal con-
a a
sides.
ductivity assigned to a material that exhibits thermal trans-
block insulation, n—rigid insulation preformed into rectangu-
mission by several modes of heat transfer resulting in
lar units.
property variation with specimen thickness, or surface emit-
board insulation, n—semirigid insulation preformed into
tance. See conductivity, thermal.
rectangular units having a degree of suppleness particularly
related to their geometrical dimensions.
DISCUSSION—Thermal conductivity and resistivity are normally con-
sidered to be intrinsic or specific properties of materials and, as such,
calcium silicate, n—insulation composed principally of hy-
should be independent of thickness. When nonconductive modes of
drous calcium silicate, and which usually contains reinforc-
heat transfer are present within the specimen (radiation, free convec-
ing fibers.
tion) this may not be the case. To indicate the possible presence of this
cellular elastomeric, n—insulation composed principally of
phenomena (for example, thickness effect) the modifier “apparent” is
natural or synthetic elastomers, or both, processed to form a
used, as in apparent thermal conductivity.
flexible, semirigid, or rigid foam which has a predominantly
DISCUSSION—Test data using the “apparent” modifier must be quoted
only for the conditions of the measurement. Values of thermal conduc- closed-cell structure.
tance (material C) and thermal resistance (material R) calculated from
cellular glass, n—insulation composed of glass processed to
apparent thermal conductivity or resistivity, are valid only for the same
form a rigid foam having a predominantly closed-cell
conditions.
structure.
DISCUSSION—Test data labeled with “apparent” shall not include any
cellular polystyrene, n—insulation composed principally of
equipment related measurement errors induced due to measurement
polymerized styrene resin processed to form a rigid foam
attempts beyond an apparatus range or calibration.
having a predominantly closed-cell structure.
cellular polyurethane, n—insulation composed principally of
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This terminology is under the jurisdiction of ASTM Committee C16 on
the catalyzed reaction product of polyisocyanate and poly-
Thermal Insulation and is the direct responsibility of Subcommittee C16.94 on
hydroxy compounds, processed usually with fluorocarbon
Terminology.
gas to form a rigid foam having a predominantly closed-cell
Current edition approved May 10, 2001. Published July 2001. Originally
structure.
published as C 168 – 41 T. Last previous edition C 168 – 00.
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Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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C 168
Q L
cellulosic fiber, n—insulation composed principally of cellu-
Flat2slab geometryl5 (1)
A DT
lose fibers usually derived from paper, paperboard stock, or
wood, with or without binders.
cement, finishing, n—a mixture of dry fibrous or powdery
where:
materials, or b
...