ASTM_D_2879_-_10.pdf

Designation:D287910Standard 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,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 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 glassand 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-temperature bath for such temperatures is used.NOTE1The 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 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 solvents,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.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 be 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 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 health 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 Specification 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 the isoteniscope to the right of point A which isfilled with vapor.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.L0.07 on Engineering Sciences of High Performance Fluids and Solids(Formally D02.1100).Current edition approved Oct.1,2010.Published October 2010.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 standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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,s,K 5 C1273.15(1)4.Summary of Test Method4.1 Dissolved and entrained fixed gases are removed fromthe sample in the isoteniscope by heating a thin layer 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 pr