1、Designation: D5002 18Standard Test Method forDensity, Relative Density, and API Gravity of Crude Oils byDigital Density Analyzer1This standard is issued under the fixed designation D5002; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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 covers the determination of the density,relative density, and API gravity of crude
3、oils that can behandled in a normal fashion as liquids at test temperaturesbetween 15 C and 35 C utilizing either manual or automatedsample injection equipment. This test method applies to crudeoils with high vapor pressures provided appropriate precau-tions are taken to prevent vapor loss during tr
4、ansfer of thesample to the density analyzer.1.2 This test method was evaluated in round robin testingusing crude oils in the 0.75 gmL to 0.95 gmL range. Lightercrude oil can require special handling to prevent vapor losses.Heavier crudes can require measurements at higher tempera-tures to eliminate
5、air bubbles in the sample.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard. The accepted units of measurement of density aregrams per millilitre and kilograms per cubic metre.1.4 This standard does not purport to address all
6、of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific warning statements are given in 7.4, 7.5
7、, and 7.6.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalB
8、arriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D287 Test Method for API Gravity of Crude Petroleum andPetroleum Products (Hydrometer Method)D941 Test Method for Density and Relative Density (Spe-cific Gravity) of Liquids by Lipkin Bicapillary Pycnom-eter (Withdrawn 1993)
9、3D1193 Specification for Reagent WaterD1217 Test Method for Density and Relative Density (Spe-cific Gravity) of Liquids by Bingham PycnometerD1250 Guide for Use of the Petroleum Measurement TablesD1298 Test Method for Density, Relative Density, or APIGravity of Crude Petroleum and Liquid Petroleum P
10、rod-ucts by Hydrometer MethodD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD4377 Test Method for Water in
11、Crude Oils by Potentiomet-ric Karl Fischer Titration3. Terminology3.1 Definitions:3.1.1 density, nmass per unit volume at a specified tem-perature.3.1.1.1 DiscussionThe SI unit of density is kg/m3; the unitof measure g/cm3is commonly used in industry. Less preferredunits, for example, kg/L or g/mL,
12、are still in use.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0D on Physical and Chemical Methods.Current edition approved Dec. 1, 2018. Published February 2019. Originallya
13、pproved in 1989. Last previous edition approved in 2016 as D5002 16. DOI:10.1520/D5002-18.2For 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 Sum
14、mary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis inte
15、rnational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Co
16、mmittee.13.1.2 relative density, nthe ratio of the density of amaterial at a stated temperature to the density of water at astated temperature.3.1.2.1 DiscussionRelative density is also commonlyknown as specific gravity. Commonly used stated temperaturesare 20 C20 C, 15 C15 C, 20 C4 C and 60 F60 F.“
17、Relative density” was historically known as the deprecatedterm “specific gravity”.3.2 Definitions of Terms Specific to This Standard:3.2.1 API gravity, na special function of relative density60 F60 F, represented by:API =141.5relative density2 131.5 (1)3.2.1.1 DiscussionNo statement of reference tem
18、peratureis required since 60 F is included in the definition.4. Summary of Test Method4.1 Approximately 1 mL to 2 mL of crude oil sample isintroduced into an oscillating sample tube and the change inoscillating frequency caused by the change in the mass of thetube is used in conjunction with calibra
19、tion data to determinethe density, relative density, and API gravity of the sample.Both manual and automated injection techniques are described.5. Significance and Use5.1 Density is a fundamental physical property that can beused in conjunction with other properties to characterize thequality of cru
20、de oils.5.2 The density or relative density of crude oils is used forthe conversion of measured volumes to volumes at the standardtemperatures of 15 C or 60 F and for the conversion of crudemass measurements into volume units.5.3 The application of the density result obtained from thistest method, f
21、or fiscal or custody transfer accountingcalculations, can require measurements of the water andsediment contents obtained on similar specimens of the crudeoil parcel.6. Apparatus6.1 Digital Density AnalyzerA digital analyzer consistingof a U-shaped, oscillating sample tube and a system forelectronic
22、 excitation, frequency counting, and display. Theanalyzer must accommodate the accurate measurement of thesample temperature during measurement or must control thesample temperature as described in 6.2 and 6.6. The instrumentshall be capable of meeting the precision requirements de-scribed in Test M
23、ethod D4052.6.2 Circulating Constant-Temperature Bath, capable ofmaintaining the temperature of the circulating liquid constantto 60.05 C in the desired range. Temperature control can bemaintained as part of the density analyzer instrument package.6.3 Syringes, at least 2 mL in volume with a tip or
24、anadapter tip that will fit the inlet of the density analyzer.6.4 Flow-Through or Pressure Adapter, for use as an alter-native means of introducing the sample into the density meter.6.5 Autosampler, required for use in automated injectionanalyses. The autosampler shall be designed to ensure theinteg
25、rity of the test specimen prior to and during the analysisand be equipped to transfer a representative portion of testspecimen to the digital density analyzer.6.6 Thermometer, calibrated and graduated to 0.1 C, and athermometer holder that can be attached to the instrument forsetting and observing t
26、he test temperature. In calibrating thethermometer, the ice point and bore corrections should beestimated to the nearest 0.05 C. Precise setting and control ofthe test temperature in the sample tube is extremely important.An error of 0.1 C can result in a change in density of one inthe fourth signif
27、icant figure.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifica
28、tions are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent wat
29、er as definedby Type II of Specification D1193 or better.7.3 Water, reagent water, freshly boiled, to remove dissolvedgasses, for use as a primary calibration standard. (WarningHandling water at boiling or near boiling temperature canpresent a safety hazard. Wear appropriate personal protectiveequip
30、ment.)7.4 Acetone, for flushing and drying the sample tube.(WarningExtremely flammable.)7.5 Petroleum Naphtha, for flushing viscous petroleumsamples from the sample tube. (WarningExtremely flam-mable.)NOTE 1Suitable solvent naphthas are marketed under various desig-nations such as “petroleum ether,”
31、 “ligroine,” or “precipitation naphtha.”7.6 n-Nonane, n-tridecane or cyclohexane, 99 % purity orbetter, or similar pure material for which the density is knownprecisely from literature references or by direct determinationin accordance with Test Method D941 or D1217.(WarningExtremely flammable.)8. S
32、ampling, Test Specimens, and Test Units8.1 Sampling is defined as all the steps required to obtain analiquot of the contents of any pipe, tank or other system, and toplace the sample into the laboratory test container. Thelaboratory test container and sample volume shall be of4Reagent Chemicals, Ame
33、rican Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formular
34、y, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5002 182sufficient dimensions to allow mixing as described in 8.3.1.Mixing is required to obtain a homogeneous sample foranalysis.8.2 Laboratory SampleUse only representative samplesobtained as specified in Practices D4057 or D4177 for thi
35、s testmethod.8.3 Test SpecimenThe aliquot of sample obtained from thelaboratory sample and delivered to the density analyzer sampletube. The test specimen is obtained as follows:8.3.1 Mix the sample of crude oil to homogenize anysediment and water present. The mixing may be accomplishedas described
36、in Practice D4177 or Test Method D4377. Mixingat room temperature in an open container can result in the lossof light ends, so mixing in closed, pressurized containers or atsub-ambient temperatures is recommended.8.3.2 Draw the test specimen from a properly mixed labo-ratory sample using an appropri
37、ate syringe.Alternatively, if theproper density analyzer attachments and connecting tubes areused then the test specimen can be delivered directly to theanalyzers sample tube from the mixing container. For auto-mated injections, it is necessary to first transfer a portion ofsample by appropriate mea
38、ns from a properly mixed laboratorysample to the autosampler vials and take the necessary steps toensure the integrity of the test specimen prior to and during theanalysis. Sample vials for the autosampler shall be sealedimmediately after filling up to 80 % 6 5 % and shall be keptclosed until the au
39、to sampler transfers the test specimen intothe measuring cell.9. Preparation of Apparatus9.1 Set up the density analyzer and constant temperaturebath following the manufacturers instructions. Adjust the bathor internal temperature control so that the desired test tempera-ture is established and main
40、tained in the sample compartmentof the analyzer. Calibrate the instrument at the same tempera-ture at which the density of the sample is to be measured.10. Calibration of Apparatus10.1 Calibrate the instrument when first setting up andwhenever the test temperature is changed. Thereafter, conductcali
41、bration checks at least weekly during routine operation ormore frequently as may be dictated by the nature of the crudeoils being measured (see 10.3).10.2 Initial calibration, or calibration after a change in testtemperature, necessitates calculation of the values of theConstants A and B from the pe
42、riods of oscillation, (T),observed when the sample cell contains certified referenceliquids such as air and freshly boiled reagent water. (SeeWarning note in 7.3.) Other calibrating materials such asn-nonane, n-tridecane, cyclohexane, and n-hexadecane (forhigh temperature applications) can also be u
43、sed as appropriate.10.2.1 While monitoring the oscillator period, T, flush thesample tube with petroleum naphtha, followed with an acetoneflush and dry with dry air. Continue drying until the displayexhibits a steady reading. In cases where saline componentscan be deposited in the cell, flush with d
44、istilled water followedby acetone and dry air. Contaminated or humid air can affectthe calibration. When these conditions exist in the laboratory,pass the air used for calibration through a suitable purificationand drying train. In addition, the inlet and outlet ports for theU-tube must be plugged d
45、uring measurement of the calibrationair to prevent ingress of moist air.10.2.2 Allow the dry air in the U-tube to come to thermalequilibrium with the test temperature and record the T-valuefor air.10.2.3 Introduce a small volume, about 1 mL to 2 mL, offreshly boiled reagent water into the sample tub
46、e using asuitable syringe. (See Warning note in 7.3.) The water must befree of even the smallest air or gas bubbles. The sample tubeshall be completely full. Allow the water to reach thermalequilibrium at the test temperature and record the T-value forwater and the test temperature.10.2.4 Alternativ
47、ely introduce one of the hydrocarbon cali-bration standards and measure the T-value as in 10.2.3.10.2.5 Calculate the density of air at the temperature of testusing the following equation:a5 0.001293273.15/T#P/101.325# g/mL (2)where:a= density of air,T = temperature, K, andP = barometric pressure, k
48、Pa.10.2.6 Determine the density of water at the temperature oftest by reference to Table 1.10.2.7 Alternatively record the density at the test tempera-ture for the hydrocarbon calibrant used in 10.2.4 as obtainedfrom an appropriate reference source or from direct determi-nation (see 7.6).10.2.8 Usin
49、g the observed T-values and the reference valuesfor water and air, calculate the values of the ConstantsAand Busing the following equations:A 5Tw22 Ta2#/w2 a# (3)TABLE 1 Density of WaterA(in vacuo)NOTE 1Several metrological entities have issued water density tablesand alternative water density data is referenced in publications external toASTM and this test method. Using water density data from an alternativerecognized source does not pose a compliance issue with this test methodas the variation in the data typically is limited t
