ASTM E41-92(2010)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: E41 − 92 (Reapproved 2010)
Standard Terminology Relating to
Conditioning
This standard is issued under the fixed designation E41; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope pressure of 76 cm Hg (101325 Pa) having a density of
3 2
13.5951 g/cm , under standard gravity of 980.665 cm/s .
1.1 Thesedefinitionspertaintotheconditioningofmaterials
for test purposes. Unless otherwise specified, they are intended
atmosphere, standard—air maintained at a specified
to apply to all cases where combinations of atmospheric
temperature, relative humidity, and standard atmospheric
influences are an essential part of the testing of materials.
pressure. E171
1.2 It is the intent of this standard to include those condi-
condition, standard—the condition reached by a specimen
tioning terms in wide use in ASTM for which standard
when it is in temperature and moisture equilibrium with a
definitions appear desirable.
standard atmosphere.
2. Referenced Documents
conditioning—the exposure of a material to the influence of a
2.1 ASTM Standards:
prescribed atmosphere for a stipulated period of time or until
E171 Practice for Conditioning and Testing Flexible Barrier
a stipulated relation is reached between material and atmo-
Packaging
sphere.
E337 Test Method for Measuring Humidity with a Psy-
dehumidify—to reduce, by any process, the quantity of water
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
vapor within a given space.
peratures)
dew point—the temperature to which water vapor must be
3. Terminology
reduced to obtain saturation vapor pressure, that is, 100 %
3.1 Definitions:
relative humidity.
air conditioning—the simultaneous control of all, or at least
NOTE 1—As air is cooled, the amount of water vapor that it can hold
thefirstthree,ofthosefactorsaffectingboththephysicaland
decreases. If air is cooled sufficiently, the actual water vapor pressure
chemical conditions of the atmosphere within any structure.
becomes equal to the saturation water-vapor pressure, and any further
These factors include temperature, humidity, motion,
cooling beyond this point will normally result in the condensation of
distribution, dust, bacteria, odor, and toxic gases.
moisture.
air, dry—air containing no water vapor.
humidify—to increase, by any process, the quantity of water
vapor within a given space.
air, saturated—a mixture of dry air and water vapor in which
the latter is at its maximum concentration for the prevailing
humidistat—a regulatory device, activated by changes in
temperature and pressure.
humidity,usedfortheautomaticcontrolofrelativehumidity.
atmospheric pressure—the pressure due to the weight of the
humidity—the condition of the atmosphere in respect to water
atmosphere. It is the pressure indicated by a barometer that
vapor. (See also humidity, absolute; humidity, relative.)
registers actual atmospheric pressure which is not corrected
to sea level equivalence. Standard atmospheric pressure is a
humidity, absolute—the weight of water vapor present in a
unit volume of air, for example, grains per cubic foot, or
grams per cubic metre.
This terminology is under the jurisdiction of ASTM Committee G03 on
Weathering and Durabilityand is the direct responsibility of Subcommittee G03.92
NOTE 2—The amount of water vapor is also reported in terms of weight
on Terminology.
per unit weight of dry air, for example, grains per pound of dry air. This
Current edition approved Dec. 1, 2010. Published December 2010. Originally
value differs from values calculated on a volume basis and should not be
approved in 1942. Last previous edition approved in 2004 as E41 – 92 (2004). DOI:
referred to as absolute humidity. It is designated as humidity ratio,
10.1520/E0041-92R10.
specific humidity, or moisture content, which also see.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
humidity ratio—in a mixture of water vapor and air, the mass
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. of water vapor per unit mass of dry air.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E41 − 92 (2010)
humidity, relative—the ratio of the actual pressure of existing room temperature—a temperature in the range of 20 to 30°C
water vapor to th
...