ASTM C168-15

Standard Terminology Relating to Thermal Insulation

SCOPE
1.1 This standard provides definitions, symbols, units, and abbreviations of terms used in ASTM standards pertaining to thermal insulating materials, and to materials associated with them.  
1.2 This terminology is not intended to be used to classify insulation materials as having particular properties. Rather, classification of insulation materials is to be done by the material standards themselves.  
1.3 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.

General Information

• Status: Historical
• Publication Date: 31-May-2015
• ICS: 01.040.91 - Construction materials and building (Vocabularies)
• ICS: 91.100.60 - Thermal and sound insulating materials
• Technical Committee: C16 - Thermal Insulation
• Drafting Committee: C16.94 - Terminology

Relations

• Replaces: ASTM C168-13 - Standard Terminology Relating to Thermal Insulation
• Effective Date: 01-Jun-2015
• Replaced By: ASTM C168-15a - Standard Terminology Relating to Thermal Insulation
• Effective Date: 15-Oct-2015
• Referred By: ASTM C1393-19 - Standard Specification for Perpendicularly Oriented Mineral Fiber Roll and Sheet Thermal Insulation for Pipes and Tanks
• Effective Date: 01-Jun-2015
• Referred By: ASTM C553-13(2019) - Standard Specification for Mineral Fiber Blanket Thermal Insulation for Commercial and Industrial Applications
• Effective Date: 01-Jun-2015
• Referred By: ASTM C1470-20 - Standard Guide for Testing the Thermal Properties of Advanced Ceramics
• Effective Date: 01-Jun-2015
• Referred By: ASTM C1485-19 - Standard Test Method for Critical Radiant Flux of Exposed Attic Floor Insulation Using an Electric Radiant Heat Energy Source
• Effective Date: 01-Jun-2015
• Referred By: ASTM C871-18(2023) - Standard Test Methods for Chemical Analysis of Thermal Insulation Materials for Leachable Chloride, Fluoride, Silicate, and Sodium Ions
• Effective Date: 01-Jun-2015
• Referred By: ASTM E241-20 - Standard Guide for Limiting Water-Induced Damage to Buildings
• Effective Date: 01-Jun-2015
• Referred By: ASTM C1045-19 - Standard Practice for Calculating Thermal Transmission Properties Under Steady-State Conditions
• Effective Date: 01-Jun-2015
• Referred By: ASTM C1130-21 - Standard Practice for Calibration of Thin Heat Flux Transducers
• Effective Date: 01-Jun-2015
• Referred By: ASTM C390-08(2019) - Standard Practice for Sampling and Acceptance of Thermal Insulation Lots
• Effective Date: 01-Jun-2015
• Referred By: ASTM C1763-20 - Standard Test Method for Water Absorption by Immersion of Thermal Insulation Materials
• Effective Date: 01-Jun-2015
• Referred By: ASTM C1879-21 - Standard Practice for Installation of Aluminum and Stainless Steel Jacketing over Thermal Insulation on Pipe and Rigid Tubing
• Effective Date: 01-Jun-2015
• Referred By: ASTM C1774-13(2019) - Standard Guide for Thermal Performance Testing of Cryogenic Insulation Systems
• Effective Date: 01-Jun-2015
• Referred By: ASTM C203-22 - Standard Test Methods for Breaking Load and Flexural Properties of Block-Type Thermal Insulation
• Effective Date: 01-Jun-2015

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C168 − 15
StandardTerminology Relating to
1
Thermal Insulation
This standard is issued under the fixed designation C168; 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 apparent thermal conductivity, λ , k , n—a thermal conduc-
a a
tivity assigned to a material that exhibits thermal transmis-
1.1 This standard provides definitions, symbols, units, and
sion by several modes of heat transfer resulting in property
abbreviations of terms used in ASTM standards pertaining to
variation with specimen thickness, or surface emittance. See
thermal insulating materials, and to materials associated with
conductivity, thermal.
them.
DISCUSSION—Thermal conductivity and resistivity are normally con-
1.2 This terminology is not intended to be used to classify
sidered to be intrinsic or specific properties of materials and, as such,
should be independent of thickness. When nonconductive modes of
insulation materials as having particular properties. Rather,
heat transfer are present within the specimen (radiation, free convec-
classification of insulation materials is to be done by the
tion) this may not be the case. To indicate the possible presence of this
material standards themselves.
phenomena (for example, thickness effect) the modifier “apparent” is
1.3 This standard does not purport to address all of the
used, as in apparent thermal conductivity.
safety concerns, if any, associated with its use. It is the
DISCUSSION—Test data using the “apparent” modifier must be quoted
responsibility of the user of this standard to establish appro-
only for the conditions of the measurement. Values of thermal conduc-
priate safety and health practices and determine the applica-
tance (material C) and thermal resistance (material R) calculated from
bility of regulatory limitations prior to use.
apparent thermal conductivity or resistivity, are valid only for the same
conditions.
2. Referenced Documents
DISCUSSION—Test data labeled with “apparent” shall not include any
2
2.1 ASTM Standards:
equipment related measurement errors induced due to measurement
attempts beyond an apparatus range or calibration.
D3574 Test Methods for Flexible Cellular Materials—Slab,
Bonded, and Molded Urethane Foams
DISCUSSION—Useofthe“apparent”modifierwithsystem Corsystem
E456 Terminology Relating to Quality and Statistics
R measurements is not permitted.
E2282 Guide for Defining the Test Result of a Test Method
apparent thermal resistivity, r , n—a thermal resistivity
a
2.2 ISO Standard:
assigned to a material that exhibits thermal transmission by
ISO 7345 Thermal Insulation—Physical Quantities and
several modes of heat transfer resulting in property variation
3
Definitions
with specimen thickness, or surface emittance. See
resistivity, thermal.
3. Terminology
DISCUSSION—Seeentirediscussionunder apparent thermal conduc-
3.1 Definitions:
tivity.
absorptance, n—the ratio of the radiant flux absorbed by a
area weight, n—weight per unit area for a specified sample, in
body to that incident upon it.
2 2
units of lb/ft (kg/m ).
absorption, n—transformation of radiant energy to a different
aerogel, n—a homogeneous, low-density solid phase material
form of energy by interaction with matter.
derived from a gel, in which the liquid component of the gel
has been replaced with a gas.
1
DISCUSSION—The resulting material has a porous structure with an
This terminology is under the jurisdiction of ASTM Committee C16 on
Thermal Insulation and is the direct responsibility of Subcommittee C16.94 on average pore size below the mean free path of air molecules at standard
Terminology.
atmospheric pressure and temperature.
CurrenteditionapprovedJune1,2015.PublishedJuly2015.Originallyapproved
in 1941. Last previous edition approved in 2013 as C168 – 13. DOI:101520/ batt, n—blanket insulation manufactured to dimensions as
C0168–15.
required by a specific application.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
blackbody, n—the ideal, perfect emitter and absorber of
Standards volume information, refer to the standard’s Document Summary page on
thermal radiation. It emits radiant energy at each wavelength
the ASTM website.
3
at the maximum rate possible as a consequence of its
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. temperature, and absorbs all incident radiance.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Sta
...

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: C168 − 13 C168 − 15
Standard Terminology Relating to
1
Thermal Insulation
This standard is issued under the fixed designation C168; 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 standard provides definitions, symbols, units, and abbreviations of terms used in ASTM standards pertaining to thermal
insulating materials, and to materials associated with them.
1.2 This terminology is not intended to be used to classify insulation materials as having particular properties. Rather,
classification of insulation materials is to be done by the material standards themselves.
1.3 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. Referenced Documents
2
2.1 ASTM Standards:
D3574 Test Methods for Flexible Cellular Materials—Slab, Bonded, and Molded Urethane Foams
E456 Terminology Relating to Quality and Statistics
E2282 Guide for Defining the Test Result of a Test Method
2.2 ISO Standard:
3
ISO 7345 Thermal Insulation—Physical Quantities and Definitions
3. Terminology
3.1 Definitions:
absorptance, n—the ratio of the radiant flux absorbed by a body to that incident upon it.
absorption, n—transformation of radiant energy to a different form of energy by interaction with matter.
apparent thermal conductivity, λ ,k ,n—a thermal conductivity assigned to a material that exhibits thermal transmission by
a a
several modes of heat transfer resulting in property variation with specimen thickness, or surface emittance. See conductivity,
thermal.
1
This terminology is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.94 on Terminology.
Current edition approved April 1, 2013June 1, 2015. Published May 2013July 2015. Originally approved in 1941. Last previous edition approved in 20102013 as
C 168 – 10.C168 – 13. DOI:101520/C0168–13.DOI:101520/C0168–15.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
DISCUSSION—
Thermal conductivity and resistivity are normally considered to be intrinsic or specific properties of materials and, as such, should be independent of
thickness. When nonconductive modes of heat transfer are present within the specimen (radiation, free convection) this may not be the case. To indicate
the possible presence of this phenomena (for example, thickness effect) the modifier “apparent” is used, as in apparent thermal conductivity.
DISCUSSION—
Test data using the “apparent” modifier must be quoted only for the conditions of the measurement. Values of thermal conductance (material C) and
thermal resistance (material R) calculated from apparent thermal conductivity or resistivity, are valid only for the same conditions.
DISCUSSION—
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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C168 − 15
Test data labeled with “apparent” shall not include any equipment related measurement errors induced due to measurement attempts beyond an
apparatus range or calibration.
DISCUSSION—
Use of the “apparent” modifier with system C or system R measurements is not permitted.
apparent thermal resistivity, r ,n—a thermal resistivity assigned to a material that exhibits thermal transmission by several modes
a
of heat transfer resulting in property variation with specimen thickness, or surface emittance. See resistivity, thermal.
DISCUSSION—
See entire discussion under apparent thermal conductivity.
2 2
area weight, n—weight per unit area for a specified sample, in units of lb/ft (kg/m ).
aerogel, n—a homogeneous, low-density solid phase material derived from a gel, in which the liquid component of the gel has
been replaced with a gas.
DISCUSSION—
The resulting material has a porous structure w
...