ASTM E337-15(2023)
(Test Method)Standard Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)
Standard Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)
SIGNIFICANCE AND USE
5.1 The object of this test method is to provide guidelines for the construction of a psychrometer and the techniques required for accurately measuring the humidity in the atmosphere. Only the essential features of the psychrometer are specified.
SCOPE
1.1 General:
1.1.1 This test method covers the determination of the humidity of atmospheric air by means of wet- and dry-bulb temperature readings.
1.1.2 This test method is applicable for meteorological measurements at the earth's surface, for the purpose of the testing of materials, and for the determination of the relative humidity of most standard atmospheres and test atmospheres.
1.1.3 This test method is also applicable when the temperature of the wet bulb only is required. In this case, the instrument comprises a wet-bulb thermometer only.
1.1.4 Relative humidity (RH) does not denote a unit. Uncertainties in the relative humidity are expressed in the form RH ± rh %, which means that the relative humidity is expected to lie in the range (RH − rh) % to (RH + rh) %, where RH is the observed relative humidity. All uncertainties are at the 95 % confidence level.
1.2 Method A—Psychrometer Ventilated by Aspiration:
1.2.1 This method incorporates the psychrometer ventilated by aspiration. The aspirated psychrometer is more accurate than the sling (whirling) psychrometer (see Method B), and it offers advantages in regard to the space which it requires, the possibility of using alternative types of thermometers (for example, electrical), easier shielding of thermometer bulbs from extraneous radiation, accidental breakage, and convenience.
1.2.2 This method is applicable within the ambient temperature range 5 °C to 80 °C, wet-bulb temperatures not lower than 1 °C, and restricted to ambient pressures not differing from standard atmospheric pressure by more than 30 %.
1.3 Method B—Psychrometer Ventilated by Whirling (Sling Psychrometer):
1.3.1 This method incorporates the psychrometer ventilated by whirling (sling psychrometer).
1.3.2 This method is applicable within the ambient temperature range 5 °C to 50 °C, wet-bulb temperatures not lower than 1 °C and restricted to ambient pressures not differing from standard atmospheric pressure by more than 30 %.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 Warning—Mercury has been designated by many regulatory agencies as a hazardous material that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additional information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be prohibited by law.
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. (For more specific safety precautionary statements, see 8.1 and 15.1.)
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E337 − 15 (Reapproved 2023)
Standard Test Method for
Measuring Humidity with a Psychrometer (the Measurement
1
of Wet- and Dry-Bulb Temperatures)
This standard is issued under the fixed designation E337; 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 1.3.2 This method is applicable within the ambient tempera-
ture range 5 °C to 50 °C, wet-bulb temperatures not lower than
1.1 General:
1 °C and restricted to ambient pressures not differing from
1.1.1 This test method covers the determination of the
standard atmospheric pressure by more than 30 %.
humidity of atmospheric air by means of wet- and dry-bulb
1.4 The values stated in SI units are to be regarded as
temperature readings.
standard. No other units of measurement are included in this
1.1.2 This test method is applicable for meteorological
standard.
measurements at the earth’s surface, for the purpose of the
testing of materials, and for the determination of the relative
1.5 Warning—Mercury has been designated by many regu-
humidity of most standard atmospheres and test atmospheres.
latory agencies as a hazardous material that can cause serious
1.1.3 This test method is also applicable when the tempera-
medical issues. Mercury, or its vapor, has been demonstrated to
ture of the wet bulb only is required. In this case, the
be hazardous to health and corrosive to materials. Caution
instrument comprises a wet-bulb thermometer only.
should be taken when handling mercury and mercury contain-
1.1.4 Relative humidity (RH) does not denote a unit. Un-
ing products. See the applicable product Safety Data Sheet
certainties in the relative humidity are expressed in the form
(SDS) for additional information. Users should be aware that
RH 6 rh %, which means that the relative humidity is expected
selling mercury and/or mercury containing products into your
to lie in the range (RH − rh) % to (RH + rh) %, where RH is
state or country may be prohibited by law.
the observed relative humidity. All uncertainties are at the 95 %
1.6 This standard does not purport to address all of the
confidence level.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.2 Method A—Psychrometer Ventilated by Aspiration:
priate safety, health, and environmental practices and deter-
1.2.1 This method incorporates the psychrometer ventilated
mine the applicability of regulatory limitations prior to use.
by aspiration. The aspirated psychrometer is more accurate
(For more specific safety precautionary statements, see 8.1 and
than the sling (whirling) psychrometer (see Method B), and it
15.1.)
offers advantages in regard to the space which it requires, the
1.7 This international standard was developed in accor-
possibility of using alternative types of thermometers (for
dance with internationally recognized principles on standard-
example, electrical), easier shielding of thermometer bulbs
ization established in the Decision on Principles for the
from extraneous radiation, accidental breakage, and conve-
Development of International Standards, Guides and Recom-
nience.
mendations issued by the World Trade Organization Technical
1.2.2 This method is applicable within the ambient tempera-
Barriers to Trade (TBT) Committee.
ture range 5 °C to 80 °C, wet-bulb temperatures not lower than
1 °C, and restricted to ambient pressures not differing from
2. Referenced Documents
standard atmospheric pressure by more than 30 %.
2
2.1 ASTM Standards:
1.3 Method B—Psychrometer Ventilated by Whirling (Sling
D861 Practice for Use of the Tex System to Designate Linear
Psychrometer):
Density of Fibers, Yarn Intermediates, and Yarns
1.3.1 This method incorporates the psychrometer ventilated
D1193 Specification for Reagent Water
by whirling (sling psychrometer).
D1356 Terminology Relating to Sampling and Analysis of
Atmospheres
1
This test method is under the jurisdiction of ASTM Committee D22 on Air
2
Quality and is the direct responsibility of Subcommittee D22.11 on Meteorology. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2023. Published February 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1931. Last previous edition approved in 2015 as E337 – 15. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0337
...
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