ASTM E1782-2003 Standard Test Method for Determining Vapor Pressure by Thermal Analysis《用热分析法测定蒸气压力的标准试验方法》.pdf
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1、Designation: E 1782 03Standard Test Method forDetermining Vapor Pressure by Thermal Analysis1This standard is issued under the fixed designation E 1782; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 measurem
3、ents 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 500 C) and for pressures between 5 kPa to2 MPa. These ranges may differ de
4、pending upon the instru-mentation used and the thermal stability of materials tested.Because a range of applied pressures is required by this testmethod, the analyst is best served by use of instrumentationreferred to as high pressure differential thermal instrumentation(HPDSC or HPDTA).1.3 Computer
5、 or electronic-based instruments, techniques,or data treatment equivalent to this test method may also beused.NOTE 1Users of this test method are expressly advised that all suchinstruments or techniques may not be equivalent. It is the responsibility ofthe user of this test method to determine the n
6、ecessary equivalency priorto use. Only the manual procedures are to be considered valid.1.4 SI value units are the standard. The customary unitsgiven in parentheses are for information only.1.5 There is no ISO standard equivalent to this test method.1.6 This standard does not purport to address all
7、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:E 177 Practice for Use
8、of the Terms Precision and Bias inASTM Test Methods2E 473 Terminology Relating to Thermal Analysis2E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2E 967 Practice for Temperature Calibration of DifferentialScanning Calorimeters/Differential Thermal An
9、alyzers2E 1142 Terminology Relating to Thermophysical Proper-ties2E 2071 Practice for Calculating Heat of Vaporization orSublimation from Vapor Pressure Data2SI 10 Standard for Use of the International System of Units(SI) The Modern Metric System33. Terminology3.1 Definitions:3.1.1 The following ter
10、ms are applicable to this test methodand can be found in either Terminology E 473 or TerminologyE 1142: boiling pressure, boiling temperature, differentialscanning calorimetry (DSC), differential thermal analysis(DTA), vapor pressure, vaporization point, vaporization tem-perature.3.2 Symbols:3.2.1 A
11、, B, CAntoine vapor pressure equation (1)4con-stants (log10, kPa, K):Antoine vapor pressure equation: Log10P 5 A 2B/T 1 C!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 instrumen
12、t operated underan applied constant vacuum/pressure between 5 kPa and 2 MPauntil a boiling endotherm is recorded. Boiling is observed atthe temperature where the specimen partial pressure equals thepressure applied to the test chamber. The pressure is recordedduring observance of the boiling endothe
13、rm and the boilingtemperature is recorded as the extrapolated onset temperature.This measurement is repeated using new specimens for each offive or more different pressures covering the pressure range ofinterest. The pressure-temperature data are fitted as Log10Pand 1/T (K1) to the Antoine vapor pre
14、ssure equation (see Fig.1). Vapor pressure values required for specific reports are thencomputed 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 TestMethods and Recommended Pr
15、actices.Current edition approved March 10, 2003. Published April 2003. Originallyapproved in 1996. Last previous edition approved in 1998 as E 1782 98.2Annual Book of ASTM Standards, Vol 14.02.3Annual Book of ASTM Standards, Vol 14.04.4The boldface numbers given in parentheses refer to a list of ref
16、erences at theend of the text.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 The capability of the assembled system after calibrationshould be periodically checked by using this method on purewater as a reference substance and c
17、omparing the derivedvapor pressure data with the NBS/NRC steam tables attachedas Appendix X1.5. 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
18、 handling and transport, for estimation of volatileorganic content (VOC), and in deriving hazard assessments.Vapor pressure and boiling temperature data are required forMaterial Safety Data Sheets (MSDS). The enthalpy of vapor-ization may also be estimated from the slope of the vaporpressure curve (
19、See Practice E 2071).6. Interferences6.1 This test method is limited to materials that exhibit asingular sharp boiling endotherm under the conditions outlinedin this test method.6.2 Oxidation, pyrolysis, or polymerization of condensedorganic materials retained at temperatures above their ambientboil
20、ing point may be encountered at the elevated pressures ofthis method. This will be observed as an exotherm or asignificantly broadened endotherm, or both, and shall not beconsidered a valid pressure-temperature datum point. Use of aninert gas for elevated pressures or for back-filling after evacu-at
21、ion of the sample chamber is recommended to minimize therisk of oxidation.6.3 Partial blockage of the pinhole in the DSC containerscould occasionally be encountered. This may be observed asnoise spikes on the boiling endotherm and shall not beconsidered a valid pressure-temperature datum point.7. Ap
22、paratus7.1 The essential equipment required to provide the mini-mum instrument capability of this test method includes (seeFig. 2):7.1.1 Differential Scanning Calorimeter (DSC) or Differen-tial Thermal Analyzer (DTA), consisting of:7.1.1.1 DSC/DTA Test Chamber, composed of a furnace(s)to provide uni
23、form controlled heating of a specimen andreference at a constant rate within the 273 to 773 K temperaturerange of this test method; a temperature sensor to provide anindication of the specimen/furnace temperature to 61K;adifferential sensor to detect a difference (temperature or heatflow) between th
24、e specimen and reference equivalent to 5 mW;and a means of sustaining an inert gas or vacuum test chamberenvironment at pressures above and below ambient.7.1.1.2 Temperature Controller, capable of executing aspecific temperature program by operating the furnace(s)FIG. 1 Vapor Pressure Curve with Exp
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