1、Designation: D5002 15D5002 16Standard Test Method forDensity and Relative Density of Crude Oils by DigitalDensity 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 revision, t
2、he 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 or relative density of crude oils that can be han
3、dled in a normalfashion as liquids at test temperatures between 15 C and 35 C. 35 C utilizing either manual or automated sample injectionequipment. This test method applies to crude oils with high vapor pressures provided appropriate precautions are taken to preventvapor loss during transfer of the
4、sample to the density analyzer.1.2 This test method was evaluated in round robin testing using crude oils in the 0.75 gmL to 0.95 gmL range. Lighter crudeoil can require special handling to prevent vapor losses. Heavier crudes can require measurements at higher temperatures toeliminate air bubbles i
5、n the sample.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.The accepted units of measurement of density are grams per millilitre and kilograms per cubic metre.1.4 This standard does not purport to address all of the safe
6、ty concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific warning statements are given in 7.4, 7.5, and 7.6.2. Referenced Docu
7、ments2.1 ASTM Standards:2D941 Test Method for Density and Relative Density (Specific Gravity) of Liquids by Lipkin Bicapillary Pycnometer (Withdrawn1993)3D1193 Specification for Reagent WaterD1217 Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham PycnometerD1250 G
8、uide for Use of the Petroleum Measurement TablesD4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD4377 Tes
9、t Method for Water in Crude Oils by Potentiometric Karl Fischer Titration3. Terminology3.1 Definitions:3.1.1 densitymass per unit volume at a specified temperature.3.1.2 relative densitythe ratio of the density of a material at a stated temperature to the density of water at a stated temperature.4.
10、Summary of Test Method4.1 Approximately 1 mL to 2 mL of crude oil sample is introduced into an oscillating sample tube and the change in oscillatingfrequency caused by the change in the mass of the tube is used in conjunction with calibration data to determine the density ofthe sample. Both manual a
11、nd automated injection techniques are described.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.04.0D on Physical and Chemical Methods.Current edition approved Dec. 15, 2015Jan.
12、1, 2016. Published February 2016. Originally approved in 1989. Last previous edition approved in 20132015 asD5002 13.D5002 15. DOI: 10.1520/D5002-15.10.1520/D5002-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Bo
13、ok of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indicat
14、ion of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be cons
15、idered the official document.*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 States15. Significance and Use5.1 Density is a fundamental physical property that can be used in co
16、njunction with other properties to characterize the qualityof crude oils.5.2 The density or relative density of crude oils is used for the conversion of measured volumes to volumes at the standardtemperatures of 15 C or 60 F and for the conversion of crude mass measurements into volume units.5.3 The
17、 application of the density result obtained from this test method, for fiscal or custody transfer accounting calculations,can require measurements of the water and sediment contents obtained on similar specimens of the crude oil parcel.6. Apparatus6.1 Digital Density AnalyzerA digital analyzer consi
18、sting of a U-shaped, oscillating sample tube and a system for electronicexcitation, frequency counting, and display. The analyzer must accommodate the accurate measurement of the sample temperatureduring measurement or must control the sample temperature as described in 6.2 and 6.56.6. The instrumen
19、t shall be capable ofmeeting the precision requirements described in Test Method D4052.6.2 Circulating Constant-Temperature Bath, capable of maintaining the temperature of the circulating liquid constant to60.05 C in the desired range. Temperature control can be maintained as part of the density ana
20、lyzer instrument package.6.3 Syringes, at least 2 mL in volume with a tip or an adapter tip that will fit the inlet of the density analyzer.6.4 Flow-Through or Pressure Adapter, for use as an alternative means of introducing the sample into the density meter.6.5 Autosampler, required for use in auto
21、mated injection analyses. The autosampler shall be designed to ensure the integrity ofthe test specimen prior to and during the analysis and be equipped to transfer a representative portion of test specimen to the digitaldensity analyzer.6.6 Thermometer, calibrated and graduated to 0.1 C, and a ther
22、mometer holder that can be attached to the instrument for settingand observing the test temperature. In calibrating the thermometer, the ice point and bore corrections should be estimated to thenearest 0.05 C. Precise setting and control of the test temperature in the sample tube is extremely import
23、ant. An error of 0.1 Ccan result in a change in density of one in the fourth significant figure.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated it is intended that allreagents shall conform to the specifications of the Com
24、mittee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.7.2 Purity of Water
25、Unless otherwise indicated, references to water shall be understood to mean reagent water as defined byType II of Specification D1193 or better.7.3 Water, reagent water, freshly boiled, to remove dissolved gasses, for use as a primary calibration standard. (WarningHandling water at boiling or near b
26、oiling temperature can present a safety hazard. Wear appropriate personal protectiveequipment.)7.4 Acetone, for flushing and drying the sample tube. (WarningExtremely flammable.)7.5 Petroleum Naphtha, for flushing viscous petroleum samples from the sample tube. (WarningExtremely flammable.)NOTE 1Sui
27、table solvent naphthas are marketed under various designations such as “petroleum ether,” “ligroine,” or “precipitation naphtha.”7.6 n-Nonane, n-tridecane or cyclohexane, 99 % purity or better, or similar pure material for which the density is knownprecisely from literature references or by direct d
28、etermination in accordance with Test Method D941 or D1217. (WarningExtremely flammable.)8. Sampling, Test Specimens, and Test Units8.1 Sampling is defined as all the steps required to obtain an aliquot of the contents of any pipe, tank or other system, and toplace the sample into the laboratory test
29、 container. The laboratory test container and sample volume shall be of sufficientdimensions to allow mixing as described in 8.3.1. Mixing is required to obtain a homogeneous sample for analysis.8.2 Laboratory SampleUse only representative samples obtained as specified in Practices D4057 or D4177 fo
30、r this testmethod.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the Uni
31、ted States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D5002 1628.3 Test SpecimenThe aliquot of sample obtained from the laboratory sample and delivered to the density analyzer sampletube. The test specimen is obtained as follows:8.3.1 Mix the sample
32、 of crude oil to homogenize any sediment and water present.The mixing may be accomplished as describedin Practice D4177 or Test Method D4377. Mixing at room temperature in an open container can result in the loss of light ends,so mixing in closed, pressurized containers or at sub-ambient temperature
33、s is recommended.8.3.2 Draw the test specimen from a properly mixed laboratory sample using an appropriate syringe.Alternatively, if the properdensity analyzer attachments and connecting tubes are used then the test specimen can be delivered directly to the analyzerssample tube from the mixing conta
34、iner. For automated injections, it is necessary to first transfer a portion of sample by appropriatemeans from a properly mixed laboratory sample to the autosampler vials and take the necessary steps to ensure the integrity ofthe test specimen prior to and during the analysis. Sample vials for the a
35、utosampler shall be sealed immediately after filling upto 80 % 6 5 % and shall be kept closed until the auto sampler transfers the test specimen into the measuring cell.9. Preparation of Apparatus9.1 Set up the density analyzer and constant temperature bath following the manufacturers instructions.
36、Adjust the bath orinternal temperature control so that the desired test temperature is established and maintained in the sample compartment of theanalyzer. Calibrate the instrument at the same temperature at which the density of the sample is to be measured.10. Calibration of Apparatus10.1 Calibrate
37、 the instrument when first setting up and whenever the test temperature is changed. Thereafter, conduct calibrationchecks at least weekly during routine operation or more frequently as may be dictated by the nature of the crude oils beingmeasured (see 10.3).10.2 Initial calibration, or calibration a
38、fter a change in test temperature, necessitates calculation of the values of the ConstantsA and B from the periods of oscillation, (T), observed when the sample cell contains certified reference liquids such as air andfreshly boiled reagent water. (See Warning note in 7.3.) Other calibrating materia
39、ls such as n-nonane, n-tridecane, cyclohexane,and n-hexadecane (for high temperature applications) can also be used as appropriate.10.2.1 While monitoring the oscillator period, T, flush the sample tube with petroleum naphtha, followed with an acetone flushand dry with dry air. Continue drying until
40、 the display exhibits a steady reading. In cases where saline components can be depositedin the cell, flush with distilled water followed by acetone and dry air. Contaminated or humid air can affect the calibration. Whenthese conditions exist in the laboratory, pass the air used for calibration thro
41、ugh a suitable purification and drying train. In addition,the inlet and outlet ports for the U-tube must be plugged during measurement of the calibration air to prevent ingress of moist air.10.2.2 Allow the dry air in the U-tube to come to thermal equilibrium with the test temperature and record the
42、 T-value for air.10.2.3 Introduce a small volume, about 1 mL to 2 mL, of freshly boiled reagent water into the sample tube using a suitablesyringe. (See Warning note in 7.3.) The water must be free of even the smallest air or gas bubbles. The sample tube shall becompletely full. Allow the water to r
43、each thermal equilibrium at the test temperature and record the T-value for water and the testtemperature.10.2.4 Alternatively introduce one of the hydrocarbon calibration standards and measure the T-value as in 10.2.3.10.2.5 Calculate the density of air at the temperature of test using the followin
44、g equation:da 50.001293273.15/T#P/101.325#g/mL (1)where:where:T = temperature, K, andP = barometric pressure, kPa.10.2.6 Determine the density of water at the temperature of test by reference to Table 1.10.2.7 Alternatively record the density at the test temperature for the hydrocarbon calibrant use
45、d in 10.2.4 as obtained from anappropriate reference source or from direct determination (see 7.6).10.2.8 Using the observed T-values and the reference values for water and air, calculate the values of the Constants A and Busing the following equations:A 5Tw22T a2#/dw 2da# (2)B 5Ta 22A 3da! (3)where
46、:where:Tw = observed period of oscillation for cell containing water, s,Ta = observed period of oscillation for cell containing air, s,dw = density of water at test temperature, g/mL, andda = density of air at test temperature, g/mL.D5002 163Alternatively, use the T and d values for the other refere
47、nce liquid if one is used.10.2.9 If the instrument is equipped to calculate density from the ConstantsAand B and the observed T-value from the sample,then enter the constants in the instrument memory in accordance with the manufacturers instructions.10.2.10 Check the calibration and adjust if needed
48、 by performing the routine calibration check described in 10.3.10.2.11 To calibrate the instrument to determine relative density, that is, the density of the sample at a given temperature referredto the density of water at the same temperature, follow 10.2.1 10.2.9, but substitute 1.000 for dw in pe
49、rforming the calculationsdescribed in 10.2.8.10.3 Since some crude oils can be difficult to remove from the sample tube, frequent calibration checks are recommended.Thesechecks and any subsequent adjustments to ConstantsAand B can be made if required, without repeating the calculation procedure.NOTE 2The need for a change in calibration is generally attributable to deposits in the sample tube that are not removed by the routine flushingprocedure. Although this condition can be compensated for by adjusting A and B, as described below, it is g
