ASTM D2879-2010 Standard Test Method for Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature of Liquids by Isoteniscope《用蒸气压力计测定液体的蒸气压力 - 温度关系及初始分解温度的标准试验.pdf
《ASTM D2879-2010 Standard Test Method for Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature of Liquids by Isoteniscope《用蒸气压力计测定液体的蒸气压力 - 温度关系及初始分解温度的标准试验.pdf》由会员分享,可在线阅读,更多相关《ASTM D2879-2010 Standard Test Method for Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature of Liquids by Isoteniscope《用蒸气压力计测定液体的蒸气压力 - 温度关系及初始分解温度的标准试验.pdf(6页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D2879 10Standard Test Method forVapor Pressure-Temperature Relationship and InitialDecomposition Temperature of Liquids by Isoteniscope1This standard is issued under the fixed designation D2879; the number immediately following the designation indicates the year oforiginal adoption or,
2、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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1
3、This test method covers the determination of the vaporpressure of pure liquids, the vapor pressure exerted by mixturesin a closed vessel at 40 6 5 % ullage, and the initial thermaldecomposition temperature of pure and mixed liquids. It isapplicable to liquids that are compatible with borosilicate gl
4、assand that have a vapor pressure between 133 Pa (1.0 torr) and101.3 kPa (760 torr) at the selected test temperatures. The testmethod is suitable for use over the range from ambient to 748K. The temperature range may be extended to include tem-peratures below ambient provided a suitable constant-tem
5、perature bath for such temperatures is used.NOTE 1The isoteniscope is a constant-volume apparatus and resultsobtained with it on other than pure liquids differ from those obtained in aconstant-pressure distillation.1.2 Most petroleum products boil over a fairly wide tem-perature range, and this fact
6、 shall be recognized in discussionof their vapor pressures. Even an ideal mixture followingRaoults law will show a progressive decrease in vaporpressure as the lighter component is removed, and this is vastlyaccentuated in complex mixtures such as lubricating oilscontaining traces of dewaxing solven
7、ts, etc. Such a mixturemay well exert a pressure in a closed vessel of as much as 100times that calculated from its average composition, and it is theclosed vessel which is simulated by the isoteniscope. Formeasurement of the apparent vapor pressure in open systems,Test Method D2878, is recommended.
8、1.3 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.4 WARNINGMercury has been designated by manyregulatory agencies as a hazardous material that can causecentral nervous system, kidney and liver damage. Mercury, orits vapor, may b
9、e hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercury containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAswebsitehttp:/www.epa.gov/mercury/faq.htmfor addi-tional information. Users should be aware
10、that selling mercuryor mercury containing products into your state or country maybe prohibited by law.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 he
11、alth practices and determine the applica-bility of regulatory limitations prior to use. For specificwarning statements, see 6.10, 6.12, and Annex A2.2. Referenced Documents2.1 ASTM Standards:2D2878 Test Method for Estimating Apparent Vapor Pres-sures and Molecular Weights of Lubricating OilsE230 Spe
12、cification and Temperature-Electromotive Force(EMF) Tables for Standardized Thermocouples3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ullagethat percentage of a closed system which isfilled with vapor.3.1.1.1 DiscussionSpecifically, on Fig. 1, that portion ofthe volume of t
13、he isoteniscope to the right of point A which isfilled with vapor.3.2 Symbols:C = temperature, C,K = temperature, K,p = pressure, Pa or torr,Pe= experimentally measured total system pressure,Pa= partial pressure due to fixed gases dissolved in sample,Pc= corrected vapor pressure, Pa or torr.t = time
14、, s,K 5 C 1 273.15 (1)1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.11 on Engineering Sciences of High Performance Fluids and Solids.Current edition approved Oct. 1, 2010. Published October 20
15、10. Originallyapproved in 1970. Last previous edition approved in 2007 as D2879 97 (2007).DOI: 10.1520/D2879-10.2For 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
16、standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 Dissolved and entrained fixed gases are removed fromthe sample in the isoteniscope by heating a thin laye
17、r of asample at reduced pressure, removing in this process theminimum amount of volatile constituents from the sample.4.2 The vapor pressure of the sample at selected tempera-tures is determined by balancing the pressure due to the vaporof the sample against a known pressure of an inert gas. Themano
18、meter section of the isoteniscope is used to determinepressure equality.4.3 The initial decomposition temperature is determinedfrom a plot of the logarithm of the vapor pressure versus thereciprocal of absolute temperature. The initial decompositiontemperature is taken as that temperature at which t
19、he plot firstdeparts from linearity as a result of the decomposition of thesample. An optional method provides for the use of isothermalrates of pressure rise for this purpose (see Annex A1). Theseare measured at several temperatures and the logarithm of therate of pressure rise is plotted versus th
20、e reciprocal of absolutetemperature. The decomposition temperature of the sample istaken to be that temperature at which the rate of increase ofpressure is sufficient to produce a rise of 185 Pa (0.0139 torr/s).NOTE 2Vapor pressures less than 133 Pa (1.0 torr), but greater than13.3 Pa (0.1 torr) at
21、a selected test temperature can be determined directlywith reduced accuracy. In some cases the tendency of the sample to retaindissolved or occluded air may prevent direct determinations of vaporpressure in this range. In such cases, data points obtained at higherpressures can be extrapolated to yie
22、ld approximate vapor pressures in thisrange.5. Significance and Use5.1 The vapor pressure of a substance as determined byisoteniscope reflects a property of the sample as receivedincluding most volatile components, but excluding dissolvedfixed gases such as air. Vapor pressure, per se, is a thermody
23、-namic property which is dependent only upon composition andtemperature for stable systems. The isoteniscope method isdesigned to minimize composition changes which may occurduring the course of measurement.6. Apparatus6.1 Isoteniscope (Fig. 1).6.2 Constant-Temperature Air Bath(Fig. 2) for use overt
24、he temperature range from ambient to 748 K, controlled to 62K in the zone occupied by the isoteniscope beyond point “A”(Fig. 1).6.3 Temperature Controller.6.4 Vacuum and Gas Handling System (Fig. 3).6.5 Pressure Measurement InstrumentationPressuretransducers of suitable ranges are the preferred mean
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