1、Designation: D 5002 99 (Reapproved 2005)An American National StandardStandard Test Method forDensity and Relative Density of Crude Oils by DigitalDensity Analyzer1This standard is issued under the fixed designation D 5002; the number immediately following the designation indicates the year oforigina
2、l adoption or, in the case of revision, the year of last revision. A number 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 covers the determination of the densityor relati
3、ve density of crude oils that can be handled in a normalfashion as liquids at test temperatures between 15 and 35C.This test method applies to crude oils with high vapor pressuresprovided appropriate precautions are taken to prevent vaporloss during transfer of the sample to the density analyzer.1.2
4、 This test method was evaluated in round robin testingusing crude oils in the 0.75 to 0.95 g/mL range. Lighter crudeoil can require special handling to prevent vapor losses.Heavier crudes can require measurements at higher tempera-tures to eliminate air bubbles in the sample.1.3 The values stated in
5、 SI units are to be regarded as thestandard. 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 of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standa
6、rd to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific warningstatements are given in 7.4, 7.5, and 7.6.2. Referenced Documents2.1 ASTM Standards:2D 941 Test Method for Density and Relative Density (Spe-cific Gravity
7、) of Liquids by Lipkin Bicapillary Pycnom-eter3D 1193 Specification for Reagent WaterD 1217 Test Method for Density and Relative Density(Specific Gravity) of Liquids by Bingham PycnometerD 1250 Guide for Use of the Petroleum MeasurementTablesD 4052 Test Method for Density and Relative Density ofLiqu
8、ids by Digital Density MeterD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 4377 Test Method for Water in Crude Oils by Potentio-metric Karl Fischer Titration3. Terminology3.1 Definitions:3.1.1 densityma
9、ss per unit volume at a specified tempera-ture.3.1.2 relative densitythe ratio of the density of a materialat a stated temperature to the density of water at a statedtemperature.4. Summary of Test Method4.1 Approximately 0.7 mL of crude oil sample is introducedinto an oscillating sample tube and the
10、 change in oscillatingfrequency caused by the change in the mass of the tube is usedin conjunction with calibration data to determine the density ofthe sample.5. Significance and Use5.1 Density is a fundamental physical property that can beused in conjunction with other properties to characterize th
11、equality of crude oils.5.2 The density or relative density of crude oils is used forthe conversion of measured volumes to volumes at the standardtemperatures of 15C or 60F and for the conversion of crudemass measurements into volume units.5.3 The application of the density result obtained from thist
12、est method, for fiscal or custody transfer accounting calcula-tions, can require measurements of the water and sedimentcontents obtained on similar specimens of the crude oil parcel.6. Apparatus6.1 Digital Density AnalyzerA digital analyzer consistingof a U-shaped, oscillating sample tube and a syst
13、em forelectronic excitation, frequency counting, and display. Theanalyzer must accommodate the accurate measurement of thesample temperature during measurement or must control the1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct r
14、esponsibility of SubcommitteeD02.04 on Hydrocarbon Analysis.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1989. Last previous edition approved in 1999 as D 5002 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Se
15、rvice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.sample temperature as described
16、 in 6.2 and 6.5. The instrumentshall be capable of meeting the precision requirements de-scribed in Test Method D 4052.6.2 Circulating Constant-Temperature Bath, capable ofmaintaining the temperature of the circulating liquid constantto 60.05C in the desired range. Temperature control can bemaintain
17、ed as part of the density analyzer instrument package.6.3 Syringes, at least 2 mL in volume with a tip or anadapter tip that will fit the inlet of the density analyzer.6.4 Flow-Through or Pressure Adapter, for use as analternative means of introducing the sample into the densitymeter.6.5 Thermometer
18、, calibrated and graduated to 0.1C, and athermometer holder that can be attached to the instrument forsetting and observing the test temperature. In calibrating thethermometer, the ice point and bore corrections should beestimated to the nearest 0.05C. Precise setting and control ofthe test temperat
19、ure in the sample tube is extremely important.An error of 0.1C can result in a change in density of one in thefourth significant 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 c
20、onform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications 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
21、the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type II of Specification D 1193.7.3 Water, redistilled, freshly boiled and cooled reagentwater for use as a primary calibration standard.7.4 Acetone, for flushin
22、g 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,” “ligroine,” or “precipitation
23、 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 D 941 or D 1217.(WarningExtremely flammable.)8. Sampling, Test Specimens, and
24、 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 ofsufficient dimensions to allow mixing as described
25、in 8.3.1.Mixing is required to obtain a homogeneous sample foranalysis.8.2 Laboratory SampleUse only representative samplesobtained as specified in Practices D 4057 or D 4177 for this testmethod.8.3 Test SpecimenThe aliquot of sample obtained fromthe laboratory sample and delivered to the density an
26、alyzersample tube. 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 in Practice D 4177 or Test Method D 4377.Mixing at room temperature in an open container can result inthe loss of ligh
27、t ends, so mixing in closed, pressurizedcontainers or at sub-ambient temperatures is recommended.8.3.2 Draw the test specimen from a properly mixed labo-ratory sample using an appropriate syringe.Alternatively, if theproper density analyzer attachments and connecting tubes areused then the test spec
28、imen can be delivered directly to theanalyzers sample tube from the mixing container.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
29、is established and maintained 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.
30、Thereafter, conductcalibration 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 theConsta
31、nts A and B from the periods of oscillation, (T),observed when the sample cell contains certified referenceliquids such as air and double-distilled boiled water. Othercalibrating materials such as n-nonane, n-tridecane, cyclohex-ane, and n-hexadecane (for high temperature applications) canalso be us
32、ed 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 di
33、stilled 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 du
34、ring 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.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC.
35、For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 5002 99 (2005)210.2
36、.3 Introduce about 0.7 mL of freshly boiled and cooleddouble-distilled water into the sample tube from the bottomopening using a suitable syringe. The water must be free ofeven the smallest air or gas bubbles. The sample tube shall becompletely full. Allow the water to reach thermal equilibriumat th
37、e test temperature and record the T-value for water and thetest temperature.10.2.4 Alternatively 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:da5 0.001293273/TP/
38、760 g/mL (1)where:T = temperature, K, andP = barometric pressure, torr.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
39、reference source or from direct determi-nation (see 7.6).10.2.8 Using the observed T-values and the reference valuesfor water and air, calculate the values of the Constants A and Busing the following equations:A 5 Tw22 Ta2#/dw2 da# (2)B 5 Ta22 A 3 da! (3)where:Tw= observed period of oscillation for
40、cell containingwater,Ta= observed period of oscillation for cell containing air,dw= density of water at test temperature, andda= density of air at test temperature.Alternatively, use the T and d values for the other referenceliquid if one is used.10.2.9 If the instrument is equipped to calculate den
41、sityfrom the Constants A and B and the observed T-value from thesample, then enter the constants in the instrument memory inaccordance with the manufacturers instructions.10.2.10 Check the calibration and adjust if needed byperforming the routine calibration check described in 10.3.10.2.11 To calibr
42、ate the instrument to determine relativedensity, that is, the density of the sample at a given temperaturereferred to the density of water at the same temperature, follow10.2.1-10.2.9, but substitute 1.000 for dwin performing thecalculations described in 10.2.8.10.3 Since some crude oils can be diff
43、icult to remove fromthe sample tube, frequent calibration checks are recommended.These checks and any subsequent adjustments to Constants Aand B can be made if required, without repeating the calcula-tion procedure.NOTE 2The need for a change in calibration is generally attributableto deposits in th
44、e sample tube that are not removed by the routine flushingprocedure.Although this condition can be compensated for by adjustingAand B, as described below, it is good practice to clean the tube with warmchromic acid solution (WarningCauses severe burns. A recognizedcarcinogen.) whenever a major adjus
45、tment is required. Chromic acidsolution is the most effective cleaning agent; however, surfactant-typecleaning fluids have also been used successfully.10.3.1 Flush and dry the sample tube as described in 10.2.1and allow the display to reach a steady reading. If the displaydoes not exhibit the correc
46、t T-value or density for air at thetemperature of test, repeat the cleaning procedure or adjust thevalue of Constant B commencing with the last decimal placeuntil the correct density is displayed.10.3.2 If adjustment to Constant B was necessary in 10.3.1then continue the recalibration by introducing
47、 freshly boiledand cooled double-distilled water into the sample tube asdescribed in 10.2.3 and allowing the display to reach a steadyreading. If the instrument has been calibrated to display thedensity, adjust the reading to the correct value for water at thetest temperature (see Table 1) by changi
48、ng the value ofConstant A, commencing with the last decimal place. If theinstrument has been calibrated to display the relative density,adjust the reading to the value 1.0000.NOTE 3In applying this periodic calibration procedure, it has beenfound that more than one value each for A and B, differing
49、in the fourthdecimal place, will yield the correct reading for the density of air andwater. The setting chosen would then be dependent upon whether it wasapproached from a higher or lower value. The setting selected by thismethod could have the effect of altering the fourth place of the readingobtained for a sample.10.4 Some analyzer models are designed to display themeasured period of oscillation only (T-values) and theircalibration requires the determination of an instrument constantK, that must be used to calculate the density or relative densityfrom
