ASTM D5032-97(2003)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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An American National Standard
Designation:D5032–97 (Reapproved 2003)
Standard Practice for
Maintaining Constant Relative Humidity by Means of
Aqueous Glycerin Solutions
This standard is issued under the fixed designation D5032; 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 3.2 Practice E104 contains methods for maintaining con-
stant relative humidity environments using aqueous saturated
1.1 This practice describes a method for obtaining constant
salt solutions or various strength sulfuric acid-water systems.
relative humidity ranging from 30 to 98% at temperatures
rangingfrom0to70°Cinrelativelysmallcontainersbymeans
4. Significance and Use
of an aqueous glycerin solution.
4.1 Controlled relative humidity environments are impor-
1.2 This practice is applicable for closed systems such as
tant for conditioning materials for shelf-life studies or for
environmental conditioning containers.
investigating the change in physical or dielectric properties
1.3 This practice is not recommended for the generation of
after exposure.
continuous (flowing) streams of constant humidity unless
4.2 The use of aqueous-glycerin solutions reduces the pos-
precautionary criteria are followed to ensure source stability.
sibility of contamination of the materials or corrosion of
1.4 This standard does not purport to address all of the
electrode systems which would be more likely to result from
safety concerns, if any, associated with its use. It is the
saturated salt or acid water solutions.
responsibility of the user of this standard to establish appro-
4.3 Applicable material specifications should state the ex-
priate safety and health practices and determine the applica-
posure conditions, including time, temperature and relative
bility of regulatory limitations prior to use.
humidity, that a material should be subjected to before subse-
2. Referenced Documents quent testing. Typical conditions are given in Practice D618.
2.1 ASTM Standards:
5. Apparatus
D618 Practice for Conditioning Plastics for Testing
3 5.1 Container, airtight, of a material not acted upon by
D4023 Terminology Relating to Humidity Measurements
coppersulfate(orwiththeglycerinsolutioncontainedinatray
E104 Practice for Maintaining Constant Relative Humidity
made of a material not acted upon by copper sulfate).
by Means of Aqueous Solutions
5.2 Refractometer, covering the range of 1.33 to 1.47
2.2 Other Documents:
4 (sodium) with an accuracy of 0.0003.
DIN50008 Constant Climates Over Aqueous Solutions
Part 1: Saturated Salt and Glycerol Solutions
6. Glycerin Solution
Part 2: Sulfuric Acid Solutions (1981)
6.1 Use a good industrial grade of glycerin (“high gravity”
and “dynamite” grades are satisfactory) in distilled water.
3. Summary of Practice
Calculate the concentration in terms of the refractive index,
3.1 Controlled relative humidity environments are gener-
(R), at 25°C for the desired relative humidity at any tempera-
ated using mixtures of glycerin and water.
ture between 0 and 70°C as follows:
2 2 2
This practice is under the jurisdiction of ASTM Committee D09 on Electrical
R 5 ~=~100 1 A! 1 A 2 ~H 1 A! 2 A! 11.3333
715.3
andElectronicInsulatingMaterialsandisthedirectresponsibilityofSubcommittee
(1)
D09.12 on Electrical Tests.
Current edition approved March 10, 2003. Published April 2003. Originally
where:
approved in 1990. Last previous edition approved in 1997 as D5032–97. DOI:
10.1520/D5032-97R03.
T = temperature of the solution, °C,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
A = 25.60−0.1950T+0.0008T , and
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
H = relative humidity, percent.
Standards volume information, refer to the standard’s Document Summary page on
6.1.1 This will give the desired relative humidity with an
the ASTM website.
Withdrawn. The last approved version of this historical standard is referenced accuracyof 60.2%ataconstanttemperatureof25°C.Atother
on www.astm.org.
constant temperatures, the error, if any, may increase with the
Available from Deutsches Institut fur Normung, 4-10 Burggrenzenstrasse
deviation of the temperature from 25°C.The relative humidity
Postfach 1107, D-1000 Berlin, Germany. Also available from American National
values at 0, 25, 50 and 70°C for a number of refractive index
Standards Institute, 25 W. 43rd St., 4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5032–97 (2003)
values are given in Table 1. Obtain the refractive index for 7.1.2 Although an airtight container is recommended, it is
intermediate values of relative humidity and temperature by desirabletohaveaventundercertainconditionsoftestorwith
plotting curves from the values in the table or by calculating some kinds of containers. (Changes in pressure may produce
from the above formula. undesirablecracksinsometypesofcontainers.)Makethevent
6.2 To prevent fungus growth in the solution, add about as small as practical as there will be a continual loss of vapor
0.1% by weight of copper sulfate to the glycerin solution.The through the vent. Check the concentration of the solution
most convenient way of measuring the copper sulfate is to periodically and adjust if necessary in this case.
prepare a saturated solution in water and add four drops of the
7.1.3 Make the surface creepage distance between the
saturated solution per 100 mL of the glycerin solution. Use a
solution and the material being conditioned long enough to
container, or tray holding the glycerin solution, made of a
preventthesolutioncreepingtothematerialbeingconditioned.
material that will not react with the copper in the copper
7.2 Temperature Fluctuations:
sulfate. If the copper is removed, fungus growth can occur,
7.2.1 Avoid temperature fluctuations. Best results are ob-
whichwillcauseloweringofthehumidityvalueoftheglycerin
tained in a controlled temperature room where the average
solution.
temperature is constant and the fluctuations are of relatively
6.3 Lossofwaterthroughevaporationwhenthecontaineris
shortduration.Coverthecontainertoshieldfromdrafts.Drafts
open, or by absorption by the material being conditioned, will
maycausetemperaturedifferencesinsidethecontainer.Chang-
reducethehumidity
...