ASTM E104-02(2012)
(Practice)Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions
Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions
SIGNIFICANCE AND USE
Standard value relative humidity environments are important for conditioning materials in shelf-life studies or in the testing of mechanical properties such as dimensional stability and strength. Relative humidity is also an important operating variable for the calibration of many species of measuring instruments.e and rate of degradation and the performance rankings produced by exposures to unfiltered open-flame carbon-arcs can be much different from that produced by exposures to other types of laboratory light sources. Typically, exposures conducted according to this practice will produce degradation faster than similar exposures conducted according to Practice D822 or D5031 and may cause different types of degradation.
4.2.2 Interlaboratory comparisons are valid only when all laboratories use the same type of carbon-arc and exposure conditions.
4.3 Reproducibility of test results between laboratories has been shown to be good when the stability of materials is evaluated in terms of performance ranking compared to other materials or to a control.4,5 Therefore, exposure of a similar material of known performance (a control) at the same time as the test materials is strongly recommended. It is recommended that at least three replicates of each material be exposed to allow for statistical evaluation of results.
4.4 Test results will depend upon the care that is taken to operate the equipment. Significant factors include regulation of line voltage, freedom from salt or other deposits from water, temperature and humidity control, and conditions of the electrodes.
4.5 All references to exposures in accordance with this practice must include a complete description of the test cycle used.
SCOPE
1.1 This practice describes one method for generating constant relative humidity (rh) environments in relatively small containers.
1.2 This practice is applicable for obtaining constant relative humidities ranging from dryness to near saturation at temperatures spanning from 0 to 50°C.
1.3 This practice is applicable for closed systems such as environmental conditioning containers and for the calibration of hygrometers.
1.4 This practice is not recommended for the generation of continuous (flowing) streams of constant humidity unless precautionary criteria are followed to ensure source stability. (See Section 9.)
1.5 CautionSaturated salt solutions are extremely corrosive, and care should be taken in their preparation and handling. There is also the possibility of corrosive vapors in the atmospheres over the saturated salt solutions.
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 and health practices and determine the applicability of regulatory limitations prior to use. For more specific safety precautionary information see 1.5 and 10.1.
General Information
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Standards Content (Sample)
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: E104 − 02 (Reapproved 2012)
Standard Practice for
Maintaining Constant Relative Humidity by Means of
1
Aqueous Solutions
This standard is issued under the fixed designation E104; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
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1.1 This practice describes one method for generating con- 2.1 ASTM Standards:
stant relative humidity (rh) environments in relatively small D1193 Specification for Reagent Water
containers. D1356 Terminology Relating to Sampling and Analysis of
Atmospheres
1.2 This practice is applicable for obtaining constant rela-
2.2 Other Document:
tive humidities ranging from dryness to near saturation at
DIN50008 “Konstantklimate uber waesserigen Loseungen”
temperatures spanning from 0 to 50°C.
(Constant Climates Over Aqueous Solutions).
1.3 This practice is applicable for closed systems such as
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Part 1: Saturated Salt and Glycerol Solutions.
environmental conditioning containers and for the calibration
of hygrometers.
3. Terminology
1.4 This practice is not recommended for the generation of
3.1 non-hygroscopic material—material which neither ab-
continuous (flowing) streams of constant humidity unless
sorbs nor retains water vapor.
precautionary criteria are followed to ensure source stability.
3.2 For definitions of other terms used in this practice refer
(See Section 9.)
to Terminology D1356.
1.5 Caution—Saturated salt solutions are extremely
corrosive, and care should be taken in their preparation and
4. Summary of Practice
handling.Thereisalsothepossibilityofcorrosivevaporsinthe
2 4.1 Standard value relative humidity environments are gen-
atmospheres over the saturated salt solutions.
erated using selected aqueous saturated salt solutions.
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
5.1 Standard value relative humidity environments are im-
priate safety, health, and environmental practices and deter-
portant for conditioning materials in shelf-life studies or in the
mine the applicability of regulatory limitations prior to use.
testing of mechanical properties such as dimensional stability
For more specific safety precautionary information see 1.5 and
and strength. Relative humidity is also an important operating
10.1.
variable for the calibration of many species of measuring
1.7 This international standard was developed in accor-
instruments.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
6. Interferences
Development of International Standards, Guides and Recom-
6.1 Temperature regulation of any solution-head space en-
mendations issued by the World Trade Organization Technical
vironment to 60.1°C is essential for realizing generated
Barriers to Trade (TBT) Committee.
relative humidity values within 60.5 % (expected).
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This practice is under the jurisdiction ofASTM Committee D22 on Air Quality
and is the direct responsibility of Subcommittee D22.11 on Meteorology.
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Current edition approved April 1, 2012. Published July 2012. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 1951. Last previous edition approved in 2007 as E104 – 02 (2007). contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
DOI: 10.1520/E0104-02R12. Standards volume information, refer to the standard’s Document Summary page on
2
Opila, R., Jr., Weschler, C. J., and Schubert, R., “Acidic Vapors Above the ASTM website.
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Saturated Salt Solutions Commonly Used for Control of Humidity,” IEEE Trans. Published by Deutsches Institut für Normung, 4-10 Burggrzfenstrasse Postfach
Components, Hybrids and Manufacturing Technology, Vol 12, No. 1, March 1989, 1107, D-1000 Berlin, Federal Republic of Germany. Also available from ANSI
pp. 114–120. Publication Office, New York, NY.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E104 − 02 (2012)
TABLE 1 Humidity Fixed Point (HFP) Salt Solutions
HFP Designation Salt Name Chemical Symbol Temperature Range (°C)
HFP 4 Caesium fluoride CsF 15 to 80
HFP 7 Lithium bromide LiBr 5 to 80
HFP 12 Lithium chloride LiCl 5 to 80
HFP 23 Potassium acetate CH COOK 10 to 30
3
HFP 33 Magnesium chloride MgCl 5to80
2
HFP 43 Potassium carbonate K CO 5t
...
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