1、Designation: D 6378 08An American National StandardStandard Test Method forDetermination of Vapor Pressure (VPX) of PetroleumProducts, Hydrocarbons, and Hydrocarbon-OxygenateMixtures (Triple Expansion Method)1This standard is issued under the fixed designation D 6378; the number immediately followin
2、g 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. Scope*1.1 This test method co
3、vers the use of automated vaporpressure instruments to determine the vapor pressure exerted invacuum by volatile, liquid petroleum products, hydrocarbons,and hydrocarbon-oxygenate mixtures. This test method issuitable for testing samples with boiling points above 0C(32F) that exert a vapor pressure
4、between 7 and 150 kPa (1.0and 21 psi) at 37.8C (100F) at a vapor-to-liquid ratio of 4:1.The liquid sample volume size required for analysis is depen-dent upon the vapor-to-liquid ratio chosen (see Note 1) and themeasuring chamber volume capacity of the instrument (see6.1.1 and Note 3).NOTE 1The test
5、 method is suitable for the determination of the vaporpressure of volatile, liquid petroleum products at temperatures from 0 to100C at vapor to liquid ratios of 4:1 to 1:1 (X = 4 to 1) and pressures upto 500 kPa (70 psi), but the precision statement (see Section 16) may notbe applicable.1.2 This tes
6、t method also covers the use of automated vaporpressure instruments to determine the vapor pressure exerted invacuum by aviation turbine fuels. This test method is suitablefor testing aviation turbine fuel samples with boiling pointsabove 0C (32F) that exert a vapor pressure between 0 and110 kPa (0
7、and 15.5 psi) at a vapor-to-liquid ratio of 4:1, in thetemperature range from 25 to 100C (77 to 212F).1.3 The vapor pressure (VPX) determined by this testmethod at a vapor-liquid ratio of 4:1 (X = 4) of gasoline andgasoline-oxygenate blends at 37.8C can be correlated to thedry vapor pressure equival
8、ent (DVPE) value determined byTest Method D 5191 (see 16.3). This condition does not applywhen the sample is aviation turbine fuel.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to addres
9、s 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 7.2-7.8.2. Referenced
10、Documents2.1 ASTM Standards:2D 323 Test Method for Vapor Pressure of Petroleum Prod-ucts (Reid Method)D 2892 Test Method for Distillation of Crude Petroleum(15-Theoretical Plate Column)D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Pet
11、roleum andPetroleum ProductsD 4953 Test Method for Vapor Pressure of Gasoline andGasoline-Oxygenate Blends (Dry Method)D 5191 Test Method for Vapor Pressure of Petroleum Prod-ucts (Mini Method)D 5842 Practice for Sampling and Handling of Fuels forVolatility MeasurementD 5854 Practice for Mixing and
12、Handling of LiquidSamples of Petroleum and Petroleum ProductsD 6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD 6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum
13、 Products andLubricantsD 6708 Practice for Statistical Assessment and Improve-ment of Expected Agreement Between Two Test Methodsthat Purport to Measure the Same Property of a Material1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the dir
14、ect responsibility of SubcommitteeD02.08 on Volatility.Current edition approved Oct. 15, 2008. Published November 2008. Originallyapproved in 1999. Last previous edition approved in 2007 as D 6378071.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
15、e at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
16、2959, United States.3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 dry vapor pressure equivalent (DVPE)a value cal-culated by a correlation equation from the total pressure (TestMethod D 5191), which is equivalent to the value obtained onthe sample by Test Method D 4953, Proc
17、edure A.3.1.2 partial pressure from dissolved air (PPA), nthepressure exerted in vacuum from dissolved air that escapesfrom the liquid phase into the vapor phase.3.1.3 Reid vapor pressure equivalent (RVPE)a value cal-culated by a correlation equation from the TPX, which isequivalent to the value obt
18、ained on the sample by Test MethodD 323.3.1.4 total pressure (TPX), nthe pressure exerted invacuum by air- and gas-containing petroleum products, com-ponents and feedstocks, and other liquids, in the absence ofundissolved water at a vapor-liquid ratio of X:1.3.1.5 vapor pressure (VPX), nthe total pr
19、essure minus thePPA in the liquid at a vapor-liquid ratio of X:1.VPX5 TPX2 PPA (1)4. Summary of Test Method4.1 Employing a measuring chamber with a built-in piston,a sample of known volume is drawn into the temperaturecontrolled chamber at 20C or higher. After sealing thechamber, the temperature of
20、the chamber is increased to aspecified value simultaneously with the first expansion. Twofurther expansions are performed to a final volume of (X+1)times that of the test specimen. After each expansion, the TPXis determined. The PPAand the solubility of air in the specimenare calculated from the thr
21、ee resulting pressures. The (VPX)iscalculated by subtracting the PPA in the liquid from TPX.NOTE 2For liquids containing very low levels of high vapor pressurecontaminants, which behave like a gas, this test method of determinationof the PPA and gases may lead to wrong results since the partial pres
22、sureof the contaminants will be included in the PPA. This effect is shown whenthe value of the PPA and gases exceeds the average maximum limit of7 kPa (1 psi).5. Significance and Use5.1 Vapor pressure is a very important physical property ofvolatile liquids for shipping and storage.5.2 The vapor pre
23、ssure of gasoline and gasoline-oxygenateblends is regulated by various government agencies.5.3 Specifications for volatile petroleum products generallyinclude vapor pressure limits to ensure products of suitablevolatility performance.5.4 In this test method, an air saturation procedure prior tothe m
24、easurement is not required, thus eliminating losses ofhigh volatile compounds during this step. This test method isfaster and minimizes potential errors from improper air satu-ration. This test method permits VPXdeterminations in thefield.5.5 This test method can be applied in online applications in
25、which an air saturation procedure prior to the measurementcannot be performed.6. Apparatus6.1 The apparatus suitable for this test method employs asmall volume, cylindrically shaped measuring chamber withassociated equipment to control the chamber temperaturewithin the range from 0 to 100C. The meas
26、uring chambershall contain a movable piston with a maximum dead volumeof less than 1 % of the total volume at the lowest position toallow sample introduction into the measuring chamber andexpansion to the desired vapor-liquid ratio. A static pressuretransducer shall be incorporated in the piston. Th
27、e measuringchamber shall contain an inlet/outlet valve combination forsample introduction and expulsion. The piston and the valvecombination shall be at the same temperature as the measuringchamber to avoid any condensation or excessive evaporation.6.1.1 The measuring chamber shall be designed to co
28、ntainbetween 5 and 15 mL of liquid and vapor and be capable ofmaintaining a vapor-liquid ratio of 4:1 to 1:1. The accuracy ofthe adjusted vapor-liquid ratio shall be within 0.05.NOTE 3The measuring chamber employed by the instruments used ingenerating the precision and bias statements were construct
29、ed of nickelplated aluminum and stainless steel with a total volume of 5 mL.Measuring chambers exceeding a 5-mL capacity can be used, but theprecision and bias statements (see Section 16) are not known to apply.6.1.2 The pressure transducer shall have a minimum opera-tional range from 0 to 200 kPa (
30、0 to 29 psi) with a minimumresolution of 0.1 kPa (0.01 psi) and a minimum accuracy of60.2 kPa (60.03 psi). The pressure measurement system shallinclude associated electronics and readout devices to displaythe resulting pressure reading.6.1.3 Electronic temperature control shall be used to main-tain
31、the measuring chamber at the prescribed temperaturewithin 60.1C for the duration of the vapor pressure measure-ment.6.1.4 A platinum resistance thermometer shall be used formeasuring the temperature of the measuring chamber. Theminimum temperature range of the measuring device shall befrom 0 to 100C
32、 with a resolution of 0.1C and an accuracy of60.1C.6.1.5 The vapor pressure apparatus shall have provisions forrinsing the measuring chamber with a solvent of low vaporpressure or with the next sample to be tested.6.2 Vacuum Pump for Calibration, capable of reducing thepressure in the measuring cham
33、ber to less than 0.01 kPa(0.001 psi) absolute.6.3 McLeod Vacuum Gauge or Calibrated ElectronicVacuum Measuring Device for Calibration, to cover at least therange from 0.01 to 0.67 kPa (0.1 to 5 mm Hg). The calibrationof the electronic vacuum measuring device shall be regularlyverified in accordance
34、with Annex A6.3 on Vacuum Sensors inTest Method D 2892.6.4 Pressure Measuring Device for Calibration, capable ofmeasuring local station pressure with an accuracy and aresolution of 0.1 kPa (1 mm Hg), or better, at the sameelevation relative to sea level as the apparatus in the laboratory.NOTE 4This
35、test method does not give full details of instrumentssuitable for carrying out this test. Details on the installation, operation, andmaintenance of each instrument may be found in the manufacturersmanual.D63780827. Reagents and Materials7.1 Purity of ReagentsUse chemicals of at least 99 %purity for
36、verification of instrument performance (see Section11). Unless otherwise indicated, it is intended that all reagentsconform to the specifications of the Committee of AnalyticalReagents of the American Chemical Society3where suchspecifications are available. Lower purities can be used,provided it is
37、first ascertained that the reagent is of sufficientpurity to permit its use without lessening the accuracy of thedetermination.7.1.1 The chemicals in 7.3, 7.4, and 7.7 are suggested forverification of instrument performance (see Section 11), basedon the reference fuels analyzed in the 2003 interlabo
38、ratorystudy (ILS) (see 16.1, Table 1, and Note 15). Such referencefuels are not to be used for instrument calibration. Table 1identifies the accepted reference value (ARV) and uncertaintylimits, as well as the acceptable testing range for each of thereference fuels listed.NOTE 5Verification fluids r
39、eported by 12 of the D 6378 data setparticipants in the 2003 ILS (see 16.1) included the following (withnumber of data sets identified in parentheses): 2,2-dimethylbutane (11),and 2,3-dimethylbutane (1).7.2 Cyclopentane,(WarningCyclopentane is flammableand a health hazard).7.3 2,2-Dimethylbutane,(Wa
40、rning2,2-dimethylbutane isflammable and a health hazard).7.4 2,3-Dimethylbutane,(Warning2,3-dimethylbutane isflammable and a health hazard).7.5 Methanol,(WarningMethanol is flammable and ahealth hazard).7.6 2-Methylpentane,(Warning2-methylpentane is flam-mable and a health hazard).7.7 Pentane,(Warni
41、ngPentane is flammable and a healthhazard).7.8 Toluene,(WarningToluene is flammable and a healthhazard).8. Sampling and Sample Introduction8.1 General Requirements:8.1.1 The extreme sensitivity of vapor pressure measure-ments to losses through evaporation and the resulting changesin composition is s
42、uch as to require the utmost precaution andthe most meticulous care in the drawing and handling ofsamples.8.1.2 Obtain a sample and test specimen in accordance withPractice D 4057, D 4177, D 5842,orD 5854 when appropriate,except do not use the Sampling by Water Displacement sectionfor fuels containi
43、ng oxygenates. Use either a 250-mL or 1-L(1-qt) sized container filled between 70 and 80 % with sample.See Note 6 on effect of sample size on testing precision.8.1.2.1 When the sample is aviation turbine fuel, use of100-mL size containers are suitable when they are filled to aminimum of 80 %.NOTE 6T
44、he current precision statements for gasoline and gasoline-oxygenate blends were derived from the 2003 ILS (see 16.1) usingsamples in 250-mL and 1-L (1-qt) clear glass containers. However,samples in containers of other sizes as prescribed in Practice D 4057 maybe used, with the same filling requireme
45、nt, but the precision can beaffected. The differences in precision results obtained from 250-mL and1-L containers were found to be statistically significant, in addition tohaving a statistically observable bias being detected between 250-mL and1-L containers. See Tables 2 and 3, as well as Figs. 1 a
46、nd 2 for morespecific details on precision differences as a function of VP4(37.8C) andcontainer size, as well as 16.3.3 for specific details on the relative biasbetween 250-mL and 1-L containers. In general, numerically betterrepeatability values were determined at VP4(37.8C) values 100 kPa, such as
47、 pentane, theprecision appears to worsen with diminishing liquid volume in the bottle.It is recommended that if pentane is used, that the % capacity in thecontainer be $50 %.NOTE 14In the 2007 ILS (see 16.1) using aviation turbine fuel, 2,2dimethylbutane was tested producing results comparable to th
48、e 2003 ILSD6378086(see 16.1). A mean of 68.6 kPa with a standard deviation of 0.3 kPa wasdetermined. In the 2007 ILS (see 16.1) with aviation turbine fuels,99.95 % toluene was tested with a mean of 7.7 kPa and standard deviationof 0.2 kPa.11.2 Values obtained within the acceptable testing rangeinter
49、vals in Table 1 indicate that the instrument is performingat the level deemed acceptable by this standard. If valuesoutside the acceptable testing range intervals are obtained,verify the quality of the pure compound(s) and re-check thecalibration of the instrument (see Section 10).NOTE 15A reference fluid consisting of a 44.0/56.0 (m/m) blend ofpentane/toluene was included in the 2003 ILS (see 16.1), but resultsindicated that the data was not normally distributed.12. Quality Control Checks12.1 After having verified that the instrument is perfo
