ASTM D4230-20
(Test Method)Standard Test Method for Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer
Standard Test Method for Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer
SIGNIFICANCE AND USE
5.1 Humidity information is important for the understanding of atmospheric phenomena and industrial processes. Measurements of the dew-point and calculations of related vapor pressures are important to quantify the humidity information.
SCOPE
1.1 This test method covers the determination of the thermodynamic dew- or frost-point temperature of ambient air by the condensation of water vapor on a cooled surface. For brevity, this is referred to in this test method as the condensation temperature.
1.2 This test method is applicable for the range of condensation temperatures from 60°C to −70°C.
1.3 This test method includes a general description of the instrumentation and operational procedures, including site selection, to be used for obtaining the measurements and a description of the procedures to be used for calculating the results.
1.4 This test method is applicable for the continuous measurement of ambient humidity in the natural atmosphere on a stationary platform.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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 specific precautionary statements, see Section 8.
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
Buy Standard
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: D4230 − 20
Standard Test Method for
Measuring Humidity with Cooled-Surface Condensation
1
(Dew-Point) Hygrometer
This standard is issued under the fixed designation D4230; 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.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2
1.1 This test method covers the determination of the ther- 2.1 ASTM Standards:
modynamic dew- or frost-point temperature of ambient air by D1356Terminology Relating to Sampling and Analysis of
the condensation of water vapor on a cooled surface. For Atmospheres
brevity, this is referred to in this test method as the condensa- D3631Test Methods for Measuring Surface Atmospheric
tion temperature. Pressure
1.2 This test method is applicable for the range of conden-
3. Terminology
sation temperatures from 60°C to−70°C.
3.1 Definitions:
1.3 This test method includes a general description of the
3.1.1 Fordefinitionsofothertermsinthistestmethod,refer
instrumentation and operational procedures, including site
to Terminology D1356.
selection, to be used for obtaining the measurements and a
3.2 Definitions of Terms Specific to This Standard:
description of the procedures to be used for calculating the
3.2.1 nonhygroscopic material, n—material that neither ab-
results.
sorbs nor retains water vapor.
1.4 This test method is applicable for the continuous mea-
3.2.2 mirror (front surface), n—apolishedsurface,usuallya
surement of ambient humidity in the natural atmosphere on a
metallic surface, on which condensates are deposited.
stationary platform.
3.3 Symbols:
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
e = vapor pressure of water vapor in moist air.
standard. e = saturation pressure of water vapor in equilibrium
i
with the plane surface of ice.
1.6 This standard does not purport to address all of the
e = saturation pressure of water vapor in equilibrium
w
safety concerns, if any, associated with its use. It is the
with the plane surface of water.
responsibility of the user of this standard to establish appro-
P = ambient pressure.
priate safety, health, and environmental practices and deter-
r = mixing ratio.
mine the applicability of regulatory limitations prior to use.
T = ambient air temperature.
For specific precautionary statements, see Section 8.
T = thermodynamic dew- or frost-point temperature.
d
1.7 This international standard was developed in accor-
RH = relative humidity with respect to ice.
i
dance with internationally recognized principles on standard-
RH = relative humidity with respect to water.
w
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Summary of Test Method
mendations issued by the World Trade Organization Technical
4.1 The ambient humidity is measured with a dew- and
Barriers to Trade (TBT) Committee.
frost-point hygrometer.
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 March 1, 2020. Published April 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1983. Last previous edition approved in 2012 as D4230–02 (2012). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D4230-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D4230 − 20
4.2 The mirror or some other surface on which the conden- 7.2 Auxiliary Equipment:
sate is deposited is provided with the means for cooling and 7.2.1 Provision shall be provided for assuring air flow past
heating, detection of condensate, and the measurement of the the dewpoint mirror without changing the pressure in the
temperature of the mirror surface. mirror chamber more than 0.5% from the ambient pressure
surrounding the sensor.An air flow of approximately 1.1 litres
4.3 Calculationsofsaturationvaporpressureoverwaterand
per minute is recommended for typical chambers.
ice as functions of temperature are provided.
7.2.2 Readout instrumentation is available with the dew-
5. Significance and Use point hygrometer.
5.1 Humidityinformationisimportantfortheunderstanding
8.
...
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: D4230 − 02 (Reapproved 2012) D4230 − 20
Standard Test Method offor
Measuring Humidity with Cooled-Surface Condensation
1
(Dew-Point) Hygrometer
This standard is issued under the fixed designation D4230; 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 test method covers the determination of the thermodynamic dew- or frost-point temperature of ambient air by the
condensation of water vapor on a cooled surface. For brevity, this is referred to in this test method as the condensation temperature.
1.2 This test method is applicable for the range of condensation temperatures from 60°C to − 70°C.to −70°C.
1.3 This test method includes a general description of the instrumentation and operational procedures, including site selection,
to be used for obtaining the measurements and a description of the procedures to be used for calculating the results.
1.4 This test method is applicable for the continuous measurement of ambient humidity in the natural atmosphere on a stationary
platform.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 8.
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.
2. Referenced Documents
2
2.1 ASTM Standards:
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D3631 Test Methods for Measuring Surface Atmospheric Pressure
3. Terminology
3.1 Definitions:
3.1.1 For definitions of other terms in this test method, refer to Terminology D1356.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 nonhygroscopic material—material, n—material that neither absorbs nor retains water vapor.
3.2.2 mirror (front surface)—surface), n—a polished surface, usually a metallic surface, on which condensates are deposited.
3.3 Symbols:
e = vapor pressure of water vapor in moist air.
e = saturation pressure of water vapor in equilibrium with the plane surface of ice.
i
e = saturation pressure of water vapor in equilibrium with the plane surface of water.
w
P = ambient pressure.
r = mixing ratio.
T = ambient air temperature.
T = thermodynamic dew- or frost-point temperature.
d
1
This test method is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.11 on Meteorology.
Current edition approved April 1, 2012March 1, 2020. Published July 2012April 2020. Originally approved in 1983. Last previous edition approved in 20072012 as
D4230 – 02 (2007).(2012). DOI: 10.1520/D4230-02R12.10.1520/D4230-20.
2
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D4230 − 20
RH = relative humidity with respect to ice.
i
RH = relative humidity with respect to water.
w
4. Summary of Test Method
4.1 The ambient humidity is measured with a dew- and frost-point hygrometer.
4.2 The mirror or some other surface on which the condensate is deposited is provided with the means for cooling and heating,
detection of condensate, and the measurement of the temperature of the mirror surface.
4.3 Calculations of saturation vapor pressure over water and ice as functions of temperature are provided.
5. Significance and Use
5.1 Humidity information is important for the understanding of atmospheric phenomena and industrial processes. Measurements
of the dew-point and calculations of related vapor pressures ar
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.