ASTM_E_1782_-_14.pdf

Designation:E178214Standard Test Method forDetermining Vapor Pressure by Thermal Analysis1This standard is issued under the fixed designation E1782;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of 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 test method describes a procedure for the determi-nation of the vapor pressure of pure liquids or melts fromboiling point measurements made using differential thermalanalysis(DTA)or differential scanning calorimetry(DSC)instrumentation operated at different applied pressures.1.2 This test method may be used for the temperature range273 to 773 K(0 to 500C)and for pressures between 0.2 kPato 2 MPa.These ranges may differ depending upon theinstrumentation used and the thermal stability of materialstested.Because a range of applied pressures is required by thistest method,the analyst is best served by use of instrumenta-tion referred to as high pressure differential thermal instrumen-tation(HPDSC or HPDTA).1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.(See also IEEE/ASTM SI 10.)1.4 There is no ISO standard equivalent to this test method.1.5 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzersE1142 Terminology Relating to Thermophysical PropertiesE2071 Practice for Calculating Heat of Vaporization orSublimation from Vapor Pressure DataIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units(SI)The Modern Metric System3.Terminology3.1 Definitions:3.1.1 The following terms are applicable to this test methodand can be found in either Terminology E473 or TerminologyE1142:boiling pressure,boiling temperature,differential scan-ning calorimetry(DSC),differential thermal analysis(DTA),vapor pressure,vaporization point,vaporization temperature.3.2 Symbols:3.2.1 A,B,CAntoine vapor pressure equation(1)3con-stants(log10,kPa,K):Antoinevaporpressureequation:Log10P 5 A 2 B/T1C!where:P=vapor pressure,kPa,andT=temperature,K.4.Summary of Test Method4.1 A specimen in an appropriate container is heated at aconstant rate within a DTA or DSC instrument operated underan applied constant vacuum/pressure between 0.2 kPa and 2MPa until a boiling endotherm is recorded.Boiling is observedat the temperature where the specimen partial pressure equalsthe pressure applied to the test chamber.The pressure isrecorded during observation of the boiling endotherm and theboiling temperature is recorded as the extrapolated onsettemperature.This measurement is repeated using new speci-mens for each of five or more different pressures covering thepressure range of interest.The pressure-temperature data arefitted as Log10P and 1/T(K1)to the Antoine vapor pressureequation(see Fig.1).Vapor pressure values required forspecific reports are then computed from the derived equation.1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on Calo-rimetry and Mass Loss.Current edition approved March 15,2014.Published April 2014.Originallyapproved in 1996.Last previous edition approved in 2008 as E1782 08.DOI:10.1520/E1782-14.2For 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 Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.2 The capability of the assembled system after calibrationshould be periodically checked by using this method on purewater as a reference substance and comparing the derivedvapor pressure data with the NBS/NRC steam tables attachedas Appendix X1.For pressures below 5 kPa,operation of theassembled system may be checked using 1-octanol(2).5.Significance and Use5.1 Vapor pressure is a fundamental thermophysical prop-erty of a liquid.Vapor pressure data are useful in processdesign and control,in establishing environmental regulationsfor safe handling and transport,for estimation of volatile