1、Designation:D503219Standard Practice forMaintaining Constant Relative Humidity by Means ofAqueous Glycerin Solutions1This standard is issued under the fixed designation D5032;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year o
2、f last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice describes a method for obtaining constantrelative humidity ranging from 30 to 98%at temperaturesranging fro
3、m 0 to 70C in relatively small containers by meansof an aqueous glycerin solution.1.2 This practice is applicable for closed systems such asenvironmental conditioning containers.1.3 This practice is not recommended for the generation ofcontinuous(flowing)streams of constant humidity unlessprecaution
4、ary criteria are followed to ensure source stability.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the appl
5、icability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by t
6、he World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD6054 Practice for Conditioning Electrical Insulating Mate-rials for Testing(Withdrawn 2012)3E104 Practice for Maintaining Constant Relati
7、ve Humidityby Means of Aqueous Solutions2.2 Other Documents:DIN50008 Constant Climates over Aqueous Solutions4Part 1:Saturated Salt and Glycerol SolutionsPart 2:Sulfuric Acid Solutions(1981)3.Summary of Practice3.1 Controlled relative humidity environments are gener-ated using mixtures of glycerin a
8、nd water.3.2 Practice E104 contains methods for maintaining con-stant relative humidity environments using aqueous saturatedsalt solutions or various strength sulfuric acid-water systems.4.Significance and Use4.1 Controlled relative humidity environments are impor-tant for conditioning materials for
9、 shelf-life studies or forinvestigating the change in physical or dielectric propertiesafter exposure.4.2 The use of aqueous-glycerin solutions reduces the pos-sibility of contamination of the materials or corrosion ofelectrode systems which would be more likely to result fromsaturated salt or acid
10、water solutions.4.3 Applicable material specifications shall state the expo-sure conditions,including time,temperature and relative hu-midity that a material is to be subjected to before subsequenttesting.Typical conditions are given in Practice D618 orD6054.5.Apparatus5.1 Container,airtight,of a ma
11、terial not acted upon bycopper sulfate(or with the glycerin solution contained in a traymade of a material not acted upon by copper sulfate).5.2 Refract meter,covering the range of 1.33 to 1.47(sodium)with an accuracy of 0.0003.6.Glycerin Solution6.1 Use a good industrial grade of glycerin(“high gra
12、vity”and“dynamite”grades have been found to be satisfactory)in1This practice is under the jurisdiction of ASTM Committee D09 on Electricaland Electronic Insulating Materials and is the direct responsibility of SubcommitteeD09.12 on Electrical Tests.Current edition approved March 1,2019.Published Mar
13、ch 2019.Originallyapproved in 1990.Last previous edition approved in 2011 as D5032 11.DOI:10.1520/D5032-19.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards
14、Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from Deutsches Institut fur Normung,4-10 BurggrenzenstrassePostfach 1107,D-1000 Berlin,Germany.Also available from American NationalStandards Institute,25 W.43rd St
15、.,4th Floor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles fo
16、r theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 distilled water.Calculate the concentration in terms of therefractive index,(R),at 25C for the desired relative humidityat any temperature between 0 and 70C as follows:R 5=1001A!21A22H1A!22 A!1715.311.3333(1)where:T=temperature of the solution,C,A=25.60 0.1950T+0.0008T2,andH=relative humidity,percent.6.1.1 This will give the desired relative hu
