ASTM D4230-02

Standard Test Method of Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer

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 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 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 and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 8.

General Information

• Status: Historical
• Publication Date: 09-Oct-2002
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.11 - Meteorology

Relations

• Replaces: ASTM D4230-83(1996)e1 - Standard Test Method of Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer
• Effective Date: 10-Oct-2002
• Replaced By: ASTM D4230-02e1 - Standard Test Method of Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer
• Effective Date: 10-Oct-2002
• Referred By: ASTM E337-15(2023) - Standard Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)
• Effective Date: 10-Oct-2002
• Referred By: ASTM B827-05(2020) - Standard Practice for Conducting Mixed Flowing Gas (MFG) Environmental Tests
• Effective Date: 10-Oct-2002
• Referred By: ASTM F2524-06(2020) - Standard Practice for Determination of Volatile Content for Formed-in-Place Gaskets (FIPG) Silicone Adhesives and Sealants for Transportation Applications
• Effective Date: 10-Oct-2002
• Referred By: ASTM D8122-21 - Standard Test Method for Determining Mass per Unit Area of Geohazard Nettings
• Effective Date: 10-Oct-2002
• Referred By: ASTM D5527-23 - Standard Practices for Measuring Surface Wind and Temperature by Acoustic Means
• Effective Date: 10-Oct-2002
• Referred By: ASTM D5011-17 - Standard Practices for Calibration of Ozone Monitors Using Transfer Standards
• Effective Date: 10-Oct-2002
• Referred By: ASTM D8446-22 - Standard Test Method for Water Vapor Content in Compressed Air Using Electronic Moisture Analyzers
• Effective Date: 10-Oct-2002

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4230 – 02
Standard Test Method of
Measuring Humidity with Cooled-Surface Condensation
1
(Dew-Point) Hygrometer
This standard is issued under the fixed designation D 4230; 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 3.2.1 nonhygroscopic material—material that neither ab-
sorbs nor retains water vapor.
1.1 This test method covers the determination of the ther-
3.2.2 mirror (front surface)—a polished surface, usually a
modynamic dew- or frost-point temperature of ambient air by
metallic surface, on which condensates are deposited.
the condensation of water vapor on a cooled surface. For
3.3 Symbols:
brevity this is referred to in this method as the condensation
temperature.
1.2 This test method is applicable for the range of conden-
e = vapor pressure of water vapor in moist air.
sation temperatures from 60°C to − 70°C.
e = saturation pressure of water vapor in equilibrium
l
1.3 This test method includes a general description of the
with the plane surface of ice.
instrumentation and operational procedures, including site
e = saturation pressure of water vapor in equilibrium
w
selection, to be used for obtaining the measurements and a
with the plane surface of water.
description of the procedures to be used for calculating the
P = ambient pressure.
results.
r = mixing ratio.
1.4 This test method is applicable for the continuous mea- T = ambient air temperature.
surement of ambient humidity in the natural atmosphere on a T = thermodynamic dew- or frost-point temperature.
d
RH = relative humidity with respect to ice.
stationary platform.
l
RH = relative humidity with respect to water.
1.5 This standard does not purport to address all of the
w
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
4.1 The ambient humidity is measured with a dew- and
priate safety and health practices and determine the applica-
frost-point hygrometer.
bility of regulatory limitations prior to use. For specific
4.2 The mirror or some other surface on which the conden-
precautionary statements, see Section 8.
sate is deposited is provided with the means for cooling and
2. Referenced Documents
heating, detection of condensate, and the measurement of the
temperature of the mirror surface.
2.1 ASTM Standards:
4.3 Calculations of saturation vapor pressure over water and
D 1356 Terminology Relating to Sampling and Analysis of
2
ice as functions of temperature are provided.
Atmospheres
D 3631 Test Methods for Measuring Surface Atmospheric
5. Significance and Use
2
Pressure
5.1 Humidity information is important for the understanding
3. Terminology
of atmospheric phenomena and industrial processes. Measure-
ments of the dew-point and calculations of related vapor
3.1 Definitions:
pressures are important to quantify the humidity information.
3.1.1 For definitions of other terms in this method, refer to
Terminology D 1356.
6. Interferences
3.2 Definitions of Terms Specific to This Standard:
6.1 This method is not applicable if other constituents in the
atmosphere condense before water vapor.
1
This test method is under the jurisdiction of ASTM Committee D22 on
Sampling and Analysis of Atmospheres and is the direct responsibility of Subcom-
mittee D22.11 on Meteorology.
Current edition approved Ocotber 10, 2002. Published December 2002. Origi-
e1
nally published as D 4230 – 83. Last previous edition D 4230 – 83(96) .
2
Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D4230–02
7. Apparatus als. A mirror-cleaning schedule, consistent with the contami-
nation rate, is necessary to maintain the initial calibration
7.1 Dew-point hygrometers, specifically designed for me-
accuracy. The user must determine the required maintenance
teorological observations are available commercially. A sche-
schedule for the specific site, by comparison of calibrations
matic arrangement of a typical optical dew-point hygrometer is
made before and after cleaning.
shown in Fig. 1.
8.2.2 Caution in performing this method should be taken if
7.1.1 The sample air flows through a small chamber.
the indicated mirror temperature is between 0°C and − 30°C.
7.1.2 Within the chamber is a mirror or surface on which the
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