ASTM D4920-98(2003)
(Terminology)Standard Terminology Relating to Moisture in Textiles
Standard Terminology Relating to Moisture in Textiles
SCOPE
1.1 This terminology is a compilation of definitions of technical terms related to moisture in textiles. Terms that are generally understood or adequately defined in other readily available sources are not included.
1.2 For other ASTM defined conditioning terms, refer to Terminology E 41. For other terms associated with textiles, refer to Terminology D 123, Relating to Textiles.
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Designation:D4920–98 (Reapproved 2003)
Standard Terminology Relating to
Moisture in Textiles
This standard is issued under the fixed designation D4920; 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 atmosphere for testing, n—air at ambient conditions of
relative humidity and temperature in which tests or experi-
1.1 This terminology is a compilation of definitions of
ments are conducted. (See also standard atmosphere for
technical terms related to moisture in textiles. Terms that are
testing.)
generally understood or adequately defined in other readily
available sources are not included.
DISCUSSION—In the hierarchy of terms, atmosphere is the generic
1.2 For other ASTM defined conditioning terms, refer to
term where the air is ambient with conditions “controlled” by local
weather and therefore variable. Atmosphere for testing is a delimited
Terminology E 41. For other terms associated with textiles,
term in which the use of the atmosphere is restricted for a certain
refer to Terminology D 123, Relating to Textiles.
purpose. In a standard atmosphere for testing, the conditions are
specified (standardized) and controlled for routine testing and for
2. Referenced Documents
testing reproducibility. On this basis, there is no real reason for not
2.1 ASTM Standards:
referring to the specified atmospheres that have been traditionally used
D 123 Terminology Relating to Textiles
for testing glass textiles or tire cords, etc., as standard atmospheres
E 41 Terminology Relating to Conditioning
for testing those materials.
commercial allowance (CA), n—an arbitrary value, equal to
3. Terminology
the commercial moisture regain, plus a specified allowance
3.1 Definitions:
for finish, used with the mass of scoured, oven-dried yarn, to
absolute humidity, n—the mass of water vapor present in a compute (1) yarn linear density, (2) the commercial or legal
unit volume of air.
mass of a shipment or delivery of any specific textile
material (see also commercial moisture regain), or (3) the
DISCUSSION—Common units of measure for absolute humidity are
mass of a specific component in the analysis of fiber blends.
grams per cubic metre or grains per cubic foot. The amount of water
D1907, D2494, D3887
vapor is also reported in terms of mass per unit mass of dry air, for
example,gramsperkilogram,orgrainsperpound,ofdryair.Thisvalue commercial mass, n—billed mass as determined by a gener-
differs from values calculated on a volume basis and should not be
ally accepted method or as agreed upon between the pur-
referred to as absolute humidity. It is designated as humidity ratio,
chaser and seller. D2494
specific humidity, or moisture pick-up.
commercial moisture content, n—in wool, the moisture
calculatedasapercentageofthemassofthewool,top,noils,
absorption, n—a process in which one material (the absor-
yarn, fabric, etc., in the “as-is” condition; that is, containing
bent) takes in or absorbs another (the absorbate); as the
whatever moisture, oil, grease, or other extraneous matter
absorption of moisture by fibers. (See also adsorption, and
that may be present. D2118
moistureequilibriumfortesting. Comparedesorption and
commercial moisture regain (CMR), n—a formally adopted,
resorption.) D4772
arbitrary value, to be used with the oven-dried mass of
adsorption, n—a process in which the surface of a solid takes
textile fibers, when calculating the commercial mass of a
on or adsorbs in an extremely thin layer molecules of gases,
shipment or delivery.
of dissolved substances, or of liquids with which it is in
contact.(Seealsoabsorptionandmoistureequilibriumfor
DISCUSSION—The assigned commercial moisture regain value is
testing. Compare desorption and resorption.)
usuallyhigherthantheexperimentalmoistureregainvalueforthesame
material.
ThisterminologyisunderthejurisdictionofASTMCommitteeD13onTextiles condition, v—to bring a material to moisture equilibrium with
and is the direct responsibility of Subcommittee D13.51 on Chemical Conditioning
a specified atmosphere.
and Performance.
desorption, n—a process in which a sorbed material is
Current edition approved Oct. 10, 1996. Published February 1997. Originally
released from another material, as the desorption of moisture
published as D 4920 – 89. Last previous edition D 4920 – 96b.
Annual Book of ASTM Standards, Vol 07.01.
from fibers; the reverse of absorption, adsorption, or both.
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4920–98 (2003)
DISCUSSION—The establishment of equilibrium between a material
dew point, n—the temperature below which condensation of
and the surrounding atmosphere is dependent upon the exposure time,
water vapor begins to take place when the atmosphere is
the difference in moisture levels between the material and the atmo-
cooled.
sphere, and motion of the air about the material. The level at which the
moisture in the textile reaches equilibrium depends upon the side from
DISCUSSION—Asairiscooled,theamountofwatervaporwhichitcan
which equilibrium is approached. Because of this difference, equilib-
hold decreases. If air is cooled sufficiently, the saturation water-vapor
rium for textiles should be approached from the dry (but not moisture-
pressure becomes equal to the actual water-vapor pressure and any
free) side which is faster. Equilibrium with air in motion is considered
further cooling beyond this point will normally result in the conden-
tobeachievedwhensuccessiveweighingsatspecifiedtimeintervalsdo
sation of moisture.
not show a change in mass greater than the tolerance established for the
humidity, n—the condition of the atmosphere in respect to
material.Ifthereisnoestablishedtolerance,consider0.1 %ofthemass
water vapor. (Compare absolute humidity and relative
after a 2-h exposure as satisfactory.
humidity.)
moisture equilibrium, n—for preconditioning, the moisture
hygrometer, n—any instrument for measuring the humidity of
condition reached by a material during free exposure to
the atmosphere.
moving air in the standard atmosphere for preconditioning.
moisture, n—as used with textiles, water absorbed, adsorbed,
D1776
or resorbed by a material. (See also water.)
moisture equilibrium, n—for testing, the condition reached
moisture as-is, n—deprecated term. See moisture content.
by a material during free exposure to moving air in a
moisture as-received, n—deprecated term. See moisture
specified atmosphere for testing. D885, D885M, D1776
content.
moisture-free, adj—in textiles, a descriptive term for a mate-
moisture content, n—that part of the total mass of a material
rial that (1) has been exposed to a flow of desiccated air at
that is absorbed or adsorbed water, compared to the total
a specified temperature until there is no further significant
mass. (Compare moisture pick-up and moisture regain.)
change in mass, or (2) has been treated by a distillation
DISCUSSION—Moisture is usually expressed as a percentage and is
process using a suitable solvent. (Syn. zero-moisture.)
calculated using the equation:
(Compare moisture equilibrium.)
C 5 100 ~A 2 D!/A
DISCUSSION—Moisture determinations frequently involve the change
in mass of an oven-dried specimen. If the air in the oven contains
where:
moisture, the oven-dried specimen will also contain some moisture
C = moisture content, %,
eventhoughitnolongershowsasignificantchangeinmass.Thisisdue
A = mass of material before drying, and
to the establishment of moisture equilibrium under the existing condi-
D = mass of the dried material.
tions. To ensure that the specimen is actually moisture-free, it must be
There is a relationship between moisture content and mois-
exposed to desiccated air until it shows no further significant change in
turepick-up since both may be calculated from the same data.
mass.Althoughheatingtextilesindessicatedairtotemperaturesashigh
as 110°C increases the rate of moisture loss without changing the final
The difference is in the bases used for calculating the percent-
equilibrium mass of the moisture-free textile, heating also increases the
ages, original versus dried material mass. The relationship
possibility of removing other matter. The distillation process may be
between moi
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