ASTM C870-96(2000)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: C 870 – 96 (Reapproved 2000)
Standard Practice for
Conditioning of Thermal Insulating Materials
This standard is issued under the fixed designation C 870; 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.
1. Scope 3.1.1.1 Discussion—This is variously referred to as mois-
ture content, or moisture “as is” or “as received.”
1.1 This practice covers the conditioning of thermal insu-
3.1.1.2 Discussion—This is also referred to as moisture
lating materials for tests. Since prior exposure of insulating
regain (frequently contracted to “regain”), or moisture content
materials to high or low humidity may affect the equilibrium
on the “oven-dry,” “moisture-free,” or “dry” basis.
moisture content, a procedure is also given for preconditioning
3.1.2 moisture equilibrium—the condition reached by a
the materials.
sample when the net difference between the amount of mois-
1.2 This standard does not purport to address all of the
ture sorbed and the amount desorbed, as shown by a change in
safety concerns, if any, associated with its use. It is the
mass, shows no trend and becomes insignificant.
responsibility of the user of this standard to establish appro-
3.1.2.1 Discussion—Superficialequilibriumwiththefilmof
priate safety and health practices and determine the applica-
air in contact with the specimen is reached very rapidly. Stable
bility of regulatory limitations prior to use.
equilibrium can be reached in a reasonable time only if the air
2. Referenced Documents towhichthesampleisexposedisinmotion.Stableequilibrium
with air in motion is considered to be realized when successive
2.1 ASTM Standards:
weighings do not show a progressive change in mass greater
C 168 Terminology Relating to Thermal Insulation
than the tolerances established for the various insulating
E 41 Terminology Relating to Conditioning
materials.
E 171 Specification for Standard Atmospheres for Condi-
3.1.3 moisture regain—the moisture in a material deter-
tioning and Testing Flexible Barrier Materials
minedunderprescribedconditions,andexpressedasapercent-
E 337 Test Method for Measuring Humidity with a Psy-
age of the mass of the moisture-free specimen.
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
3.1.3.1 Discussion—Moisture regain calculations are com-
peratures)
monly based on the mass of a specimen that has been dried by
2.2 ISO Standard:
heating in an oven. If the air in the oven contains moisture, the
ISO 544 Standard Atmospheres for Conditioning and/or
oven-dried specimen will contain some moisture even when it
Testing
no longer shows a significant change in mass. In order to
3. Terminology
ensurethatthespecimenismoisture-free,itmustbeexposedto
desiccated air until it shows no further significant change in its
3.1 Definitions—Definitions of terms in the field of thermal
mass. For drying temperatures above 100°C (212°F), the
insulating materials are given in Terminology C 168. The
moisture content of the oven atmosphere is negligible.
following definitions are derived from Terminology E 41:
3.1.3.2 Discussion—Moisture regain may be calculated
3.1.1 moisture content—the moisture present in a material,
frommoisturecontentusingEq1,andmoisturecontentmaybe
as determined by definite prescribed methods, expressed as a
calculated from moisture regain using Eq 2 as follows:
percentage of the mass of the sample on either of the following
bases: (1) original mass (see 3.1.1); (2) moisture-free weight
C
R 5 3 100 (1)
(see 3.1.2).
100 2 C
R
C 5 3 100 (2)
1 100 1 R
This practice is under the jurisdiction of ASTM Committee C16 on Thermal
Insulation and is the direct responsibility of Subcommittee C16.31 on Chemical and
where:
Physical Properties.
Current edition approved Dec. 10, 1996. Published February 1997. Originally C = moisture content, % (see 3.1.1), and
published as C 870 – 77. Last previous edition C 870 – 77.
R = moisture regain, % (see 3.1.3).
Annual Book of ASTM Standards, Vol 04.06.
3.2 Definitions of Terms Specific to This Standard—The
Annual Book of ASTM Standards, Vol 14.04.
following descriptions apply only to the usage of terms in this
Annual Book of ASTM Standards, Vol 15.09.
Annual Book of ASTM Standards, Vol 11.03. practice:
Available from American National Standards Institute, 11 West 42nd Street,
13th Floor, New York, NY 10036.
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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.
C 870
3.2.1 conditioned moisture equilibrium—The moisture con- necessary to standardize the humidity and temperature condi-
ditionreachedbyasampleorspecimenduringfreeexposureto tions to which insulating materials are subjected prior to and
movingaircontrolledatspecifiedconditions.Fortestpurposes, during testing.
moisture equilibrium must be reached by absorption, starting
NOTE 1—In some cases (for example, dimensionally unstable materi-
from a relatively low moisture content (see 3.2.4). Moisture
als), the dry mass cannot easily be established and original mass has to be
equilibrium for testing is considered to have been reached
used.
when the rate of increase in the mass of a sample or specimen
5.2 It may be important to the user of thermal insulation to
does not exceed that specified for the material being tested. In
know physical properties (influenced by humidity) at the
the absence of a specified rate, an increase of less than 0.1 %
ambient conditions of use, as well as at standard conditions
of the sample mass after a 24-h exposure is considered
customarily specified for testing. In such instances, those
satisfactory.
special ambient conditions should be stated in the pertinent
3.2.2 preconditioned moisture equilibrium—The moisture
material specifications and test methods.
condition reached by a sample or specimen after exposure to
movingairatthestandardatmosphereforpreconditioning.The
6. Apparatus
final condition may be established after a specified period of
time, or at a moisture equilibrium that is considered to have 6.1 Conditioning Room or Chamber:
been reached when the change in mass of a specimen in
6.1.1 Equipment for maintaining the standard atmosphere
successive weighings made at intervals of not less than 2 h
fortestinginsulatingmaterialsthroughouttheroomorchamber
does not exceed 0.2 % of the mass of the specimen.
within the tolerance given in 3.2.4, and including facilities for
circulating the air over the exposed sample or specimen or,
3.2.2.1 Discussion—Because the standard preconditioning
atmosphere covers a range of relative humidities, the close alternatively, facilities such as a revolving rack for moving the
specimens in the prevailing atmosphere.
approachtoequilibriumis,ingeneral,warrantedonlyatthetop
of the range.At lower humidities exposure for several hours is
6.1.2 Equipment for recording the temperature and relative
usually sufficient.
humidity of the air in the conditioning room or chamber.
3.2.3 standard conditioning atmosphere—Air maintained at
6.2 Instrumentation, for checking the
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